TW202449121A - Liquid-crystalline medium - Google Patents

Abstract

The present invention relates to liquid-crystalline (LC) media and to energy saving liquid-crystal displays (LCDs) containing these media, especially to displays addressed by an active matrix and in particular to LC displays of the TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, SA-HB-FFS, SA-XB-FFS, polymer stabilised SA-HB-FFS, polymer stabilised SA-XB-FFS, positive VA or positive PS-VA type.

Description

Liquid crystal medium

The invention relates to liquid crystal (LC) media and energy-saving liquid crystal displays (LCDs) containing such media, in particular to displays addressed by active matrix and in particular to LC displays of the following types: TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, SA-HB-FFS, SA-XB-FFS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA or positive PS-VA type. In a preferred embodiment, the LC media have positive dielectric anisotropy.

Liquid crystal displays ( LCDs ) are used in many fields to display information. LCDs are used in both direct-view and projection displays. Electro-optical modes used are, for example, twisted nematic ( TN ), super twisted nematic (STN), optically compensated bend ( OCB ), and electrically controlled birefringence ( ECB ) modes along with various modifications and other modes. All of these modes utilize electric fields generated substantially perpendicular to the substrate and LC layer.

In addition to these modes, there are also electro-optical modes which utilize an electric field which is substantially parallel to the substrate or LC layer. For example, WO 91/10936 discloses an LC display in which the electrical signal is generated in such a way that the electric field has a significant component parallel to the LC layer, and the LC display is thereafter referred to as an in - plane switching (IPS) display. The principle of operating this display is described, for example, by RA Soref in Journal of Applied Physics, Vol. 45, No. 12, pp. 5466-5468 (1974).

IPS displays contain an LC layer between two substrates with a planar orientation, wherein two electrodes are arranged on only one of the two substrates and preferably have an interdigitated, comb-like structure. When a voltage is applied to the electrodes, an electric field with a significant component parallel to the LC layer is generated between them. This causes the LC molecules to realign in the plane.

For example, EP 0 588 568 discloses various possibilities for designing electrodes and for addressing IPS displays. DE 198 24 137 likewise describes various embodiments of such IPS displays.

Liquid-crystal materials for IPS displays of this type are described, for example, in DE 195 28 104.

Furthermore, so-called " fringe - field switching" (FFS) displays have been reported (see, inter alia, SH Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which are equivalent to containing two electrodes on the same substrate, one of which is structured in a comb-like manner and the other is unstructured. Thus, a strong so-called "fringe field" is generated, i.e. a strong electric field near the electrode edge and an electric field with both a strong vertical component and a strong horizontal component in the entire unit. FFS displays have a low viewing angle dependence of the contrast. FFS displays generally contain an LC medium with positive dielectric anisotropy and an alignment layer, generally composed of polyimide, which provides a planar alignment for the molecules of the LC medium.

Liquid crystal displays in the IPS and FFS electro-optical modes are particularly suitable for modern desktop monitors, televisions and multimedia applications. The LC medium according to the invention is preferably used in displays of this type. Generally speaking, positive dielectric LC media with relatively low dielectric anisotropy values are used in FFS displays, but in some cases LC media with dielectric anisotropy values of only about 3 or even less are also used in IPS displays.

A further improvement has been achieved with the HB-FFS mode. Compared to conventional FFS technology, a unique feature of the HB-FFS mode is its ability to achieve higher transmittance, allowing the panel to be operated with less power consumption.

Another recently developed mode is the XB-FFS mode, in which the LC medium additionally contains polar liquid crystal compounds with low dielectric anisotropy.

Liquid crystal compositions suitable for LCDs and in particular for FFS and IPS displays are known from the prior art, for example from JP 07-181 439 (A), EP 0 667 555, EP 0 673 986, DE 195 09 410, DE 195 28 106, DE 195 28 107, WO 96/23 851 and WO 96/28 521. However, these compositions have certain disadvantages. Among other disadvantages, most of them lead to disadvantageously long addressing times, have inappropriate resistivity values and/or require too high an operating voltage. To this end, improvements in the operating properties and also the shelf life are necessary.

FFS and IPS displays can be operated as active - matrix displays (AMD) or passive - matrix displays (PMD). In the case of active-matrix displays, the individual pixels are generally addressed by integrated non-linear active elements such as, for example, thin - film transistors (TFTs), whereas in the case of passive - matrix displays, the individual pixels are generally addressed by multiplexing methods as are known from the prior art.

The display according to the invention is preferably addressed by an active matrix, preferably by a TFT matrix. However, the LC medium according to the invention can also be advantageously used in displays having other known addressing methods.

Typical applications of In-Plane Switching (IPS) and Edge Field Switching (FFS) technologies are monitors, laptops, TVs, mobile phones, tablet computers, etc.

Both IPS and FFS technologies have certain advantages over other LCD technologies, such as vertical alignment (VA) technology, such as the wide viewing angle dependence of contrast.

Providing alternative LC media and their use in displays with high transmission, good black state and high contrast is a core challenge for modern FFS and IPS applications. In addition, modern applications also require good low temperature stability and fast addressing times.

To date, it has not been possible to design suitable LC media with high contrast (e.g. high elastic constants _K1 and _Kav ), low temperature stability and low response time. Therefore, the overall image quality in these devices still needs further improvement.

The object of the invention is to provide LC media having advantages particularly for energy-saving FFS and IPS displays, and also for TN, positive VA or STN displays, and particularly for active matrix displays (e.g. those addressed by means of TFTs), which do not or only to a lesser extent exhibit the disadvantages indicated above and have a combination of a high average elastic constant _Kav with a low response time parameter ( _γ1 / _K1 ) and a low rotational viscosity, a relatively low birefringence Δn. In addition, they need to have a high specific resistance, a low critical voltage, a high dielectric anisotropy, good low temperature stability (LTS), a fast response time and achieve a high brightness. In the case of FFS displays, it is necessary to further optimize the response time, contrast, brightness and reliability. However, it has been found that prior art LC materials are generally unable to meet all of these requirements simultaneously.

Surprisingly, the above technical problem is solved by providing an LC medium as described and claimed hereinafter.

It has now been surprisingly found that LC media according to the present invention containing a combination of compounds of formula I, LP1 and/or LP2 show several significant improvements. The individual substituents are specified in technical solution 1, especially when used in FFS mode displays, such as a combination of high average elastic constant _Kav , low reaction time parameter ( _γ1 / _K1 ) and low rotational viscosity and good solubility, and a fast reaction time is achieved.

In addition, the LC medium according to the invention has high definition bright spots, excellent low temperature stability (LTS) and provides the best dynamic image quality and improved overall image quality, especially high contrast.

The invention relates to an LC medium, characterized in that it comprises one or more compounds of the formula I wherein the individual substituents have the following meanings, identically or differently and independently of one another, on each occurrence: R ¹¹ and R ¹² each independently represent an H atom, an alkyl or alkoxy group having 1 to 12 C atoms, or an alkenyl or alkenyloxy group having 2 to 12 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, or a cycloalkyl or cycloalkoxy group having 3 to 12 C atoms, one or more H atoms thereof may be replaced by a halogen atom, preferably a cyclopentyl or cyclopentyloxy group, Z ¹ represents a single bond, -CH ₂ -CH ₂ - or -COO-; and one or more compounds selected from the group consisting of the following formulae LP1 and LP2 wherein the individual substituents have the following meanings on each occurrence, identically or differently and independently of one another: R ⁰ is an alkyl or alkoxy group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- are substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, ^R2 is an alkyl or alkoxy group having 1 to 6 C atoms, wherein one or more _CH2 groups are optionally replaced by -C≡C-, _-CF2O- , _-OCF2- , -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, ^X2 is a F atom or an alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl or alkenyloxy group having 2 to 6 C atoms, wherein one or more H atoms are replaced by an F atom, ^L1 and ^L2 are independently H, F or Cl, ^{Y0 is} H or _CH3 , and n and m are independently 0, 1 or 2.

The LC medium according to the invention is particularly suitable for use in the following LC displays: FFS, HB-FFS, XB-FFS and IPS modes based on positive dielectric liquid crystals, and polymer-stabilized variants thereof.

The invention further relates to the use of an LC medium as described above and below for electro-optical purposes, in particular in LC displays, shutter glasses, LC windows, 3D applications, preferably in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FFS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA and positive PS-VA displays, very preferably in FFS, HB-FFS, IPS, PS-HB-FFS and PS-IPS displays.

The invention further relates to an electro-optical LC display comprising an LC medium as described above and below, in particular a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FFS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA or positive PS-VA display, preferably a FFS, HB-FFS, IPS, PS-HB-FFS or PS-IPS display.

In this application, all atoms also include their isotopes. In some embodiments, one or more hydrogen atoms (H) can be replaced by deuterium (D) as needed; high deuteration enables or simplifies the analytical determination of compounds, especially at low concentrations.

In formula I, LP1 and LP2, if R ⁰ , R ¹¹ , R ¹² and R ² represent alkyl and/or alkoxy groups, this may be a straight chain or a branched chain. It is preferably a straight chain having 2, 3, 4, 5 or 6 C atoms and preferably represents ethyl, propyl, butyl, pentyl, hexyl, ethoxy, propoxy, butoxy, pentyloxy or hexyloxy, in addition to methyl, methoxy. ^{R 0} preferably represents a straight chain alkyl group having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms.

Oxahedral alkyl preferably represents linear 2-oxahedral propyl (= methoxymethyl), 2-(= ethoxymethyl) or 3-oxahedral butyl (= 2-methoxyethyl), 2-, 3- or 4-oxahedral pentyl, 2-, 3-, 4- or 5-oxahedral hexyl.

If R ⁰ , R ¹¹ , R ¹² or R ² represents an alkoxy group or an oxyalkyl group, it may also contain one or more further oxygen atoms, with the proviso that the oxygen atoms are not directly linked to one another.

In another preferred embodiment, one or more of R ⁰ , R ¹¹ , R ¹² and R ² are selected from the group consisting of: , , , , , , , , -S ¹ -F, -OS ¹ -F, -OS ₁ -OS ₂ , wherein S ¹ is C _1-12 -alkylene or C _2-12 -alkenylene and S ² is H, C _1-12 -alkyl or C _2-12 -alkenyl, and most preferably one or more of R ⁰ , R ¹¹ , R ¹² and R ² are selected from the group consisting of: , , , , , , , , , , , , , -OCH ₂ OCH ₃ , -O(CH ₂ ) ₂ OCH ₃ , -O(CH ₂ ) ₃ OCH ₃ , -O(CH ₂ ) ₄ OCH ₃ , -O(CH ₂ ) ₂ F, -O(CH ₂ ) ₃ F, -O(CH ₂ ) ₄ F.

If R ⁰ , R ¹¹ , R ¹² or R ² represents an alkenyl group, this may be straight chain or branched. It is preferably straight chain and has 2 to 10 C atoms. Thus, it particularly denotes vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.

If R ⁰ , R ¹¹ , R ¹² or R ² represents an alkyl or alkenyl group which is at least monosubstituted by a halogen, this group is preferably a straight chain and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting groups also include perfluorinated groups. In the case of monosubstitution, the fluorine or chlorine substituent may be in any desired position, but is preferably in the ω position.

In formula LP2, ^X2 is preferably a F atom or a mono- or polyfluorinated alkyl or alkoxy group having 1, 2 or 3 C atoms or a mono- or polyfluorinated alkenyl group having 2 or 3 C atoms. ^X2 is particularly preferably F, _CF3 , _CHF2 , _OCF3 , _{OCHF2 , OCFHCF3} , _OCFHCHF2 , _OCFHCHF2 , OCF2CH3, _OCF2CHF2 , _OCF2CHF2 , _OCF2CF2CHF2 , _OCF2CF2CHF2 , OCFHCF2CF3 _, OCFHCF2CHF2, OCF2CF2CF3, OCFHCF2CHF2, _OCF2CF2CF3 , OCH= _CF2 or CH _{= CF2} , very _{particularly preferably} F _{or CF3 , furthermore OCF3 ,} OCF _{= CF2 , OCHF2} or _{OCH = CF2 .}

In the compounds of formula I and its subformulae, R ¹¹ and R ¹² preferably represent straight-chain alkyl having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms, most preferably methyl, ethyl or propyl, most preferably n-propyl and vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl and 1-pentenyl. Preferred compounds of formula I are those wherein Z ¹ represents a single bond.

In a preferred embodiment, the compound of formula I can be selected from the following sub-formulas I-1 to I-3: wherein R ¹¹ and R ¹² each independently represent an H atom, an alkyl or alkoxy group having 1 to 6 C atoms, or an alkenyl or alkenyloxy group having 2 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO-, wherein the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, preferably an F atom, or a cycloalkyl or cycloalkoxy group having 3 to 6 C atoms, wherein one or more H atoms thereof may be replaced by a halogen atom, preferably a cyclopentyl or cyclopentyloxy group.

Although the selection of substituents R ¹¹ and R ¹² in formula I is not particularly limited, it is particularly advantageous to select R ¹¹ and R ¹² as alkyl or cycloalkyl groups having 1 to 6 C atoms, wherein R ¹ is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and cyclopentyl. R ¹¹ and R ¹² may also be advantageously selected from unbranched alkenyl groups such as vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, and 5-hexenyl.

In particular, the selection of the following compounds of formula I appears to be highly advantageous: Herein, "alkyl" and "alkyl*" represent C _1-6 -alkyl groups, and "cycloalkyl" represents C _3-6 -cycloalkyl groups.

With regard to the overall combination of characteristics of the medium obtained, the use of compounds of sub-formula I-1, in particular those of sub-formulae I-1-1 to I-1-11, is most advantageous.

The proportion of the compound of formula I or preferably of its subformula I-1-1 or I-1-2 in the LC medium is preferably 0.5 to 20% by weight, very preferably 1 to 15% by weight, most preferably 2 to 10% by weight.

The compounds of the general formula LP1 and LP2 can be represented by one of the following: wherein R ⁰ is an alkyl or alkoxy group having 1 to 12 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, preferably an alkyl group having 1 to 4 C atoms, an alkenyl group or alkenyloxy group having 2 to 6 C atoms, or a cycloalkyl group or cycloalkoxy group having 3 to 6 C atoms, wherein vinyl, allyl or cyclopentyl is particularly preferred, n represents 1, 2, 3, 4 or 5, and m represents 1, 2, 3 or 4.

In another embodiment, one or more compounds of Formula LP1 and LP2 are described by the following Formulas LP1-1 and LP2-1: wherein R ⁰ is an alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- are substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, R ² is an alkyl group having 1 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in such a way that the O atoms are not directly linked to each other and one or more H atoms thereof may be replaced by a halogen atom, X ² F atom or an alkyl or alkoxy group having 1 to 3 C atoms or an alkenyl or alkenyloxy group having 2 or 3 C atoms, one or more H atoms thereof are replaced by a F atom, and Y ⁰ H or CH ₃ .

Particularly preferred compounds of formula LP1 are those selected from the group consisting of the following subformulae: Wherein ^Y0 is H or _CH3 , preferably H.

The most preferred compounds are compounds of formula LP1-1a, LP1-1b and LP1-1c, and the most preferred compound is compound of formula LP1-1a.

Particularly preferred compounds of formula LP2 are those selected from the group consisting of the following subformulae: Wherein ^Y0 is H or _CH3 , preferably H.

The most preferred compounds are compounds of formula LP2-1a, LP2-1b, LP2-1c, LP2-1d and LP2-1i, and the most preferred compound is compound of formula LP2-1b.

The proportion of compounds of the formula LP1 or LP2 or subformulae thereof in the LC medium is preferably 2 to 35% by weight, very preferably 3 to 30% by weight, most preferably 4 to 20% by weight.

Preferably, the LC medium contains 1, 2 or 3 compounds of formula LP1 or LP2 or their subformulae. In a particularly preferred embodiment, the LC medium comprises at least one compound of formula LP1 and at least one compound of formula LP2.

Other components In a preferred embodiment, the LC medium may also contain one or more compounds selected from the following formulae II and III: where the individual substituents, independently of one another and identically or differently on each occurrence, have the following meanings: ^R0 is one of the meanings given for ^R11 and ^R12 , ^X0 is independently F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkoxy or halogenated alkenyloxy having up to 6 C atoms, ^L1-6 are independently H or F, ^{and Y0} is H or _CH3 . Preferred compounds of formula II and III are those ^{wherein Y0} is H.

Further preferred compounds of the formulae II and III are those in which R ⁰ represents alkyl having 1 to 6 C atoms, very preferably ethyl or propyl, and X ⁰ represents F or OCF ₃ , very preferably F.

In a preferred embodiment, the LC medium comprises one or more compounds of formula II selected from the following subformulae: wherein R ⁰ and X ⁰ have the meanings given in Formula II.

Preferred compounds are those of formula II-1, II-2 and II-3, and most preferred are those of formula II-1 and II-2.

In the compounds of formulae II-1 to II-7, R ⁰ preferably represents an alkyl group having 1 to 6 C atoms, most preferably ethyl or propyl, and X ⁰ preferably represents F or OCF ₃ , most preferably F.

In one embodiment, the LC medium contains one or more compounds of formula II or its subformulae as described above and below, wherein ^Y0 is _CH3 . Very preferably, the LC medium according to this preferred embodiment comprises one or more compounds of formula II selected from the following subformulae: wherein R ⁰ and X ⁰ have the meanings given in Formula II.

Preferred compounds are those of Formula IIA-1, IIA-2 and IIA-3, and most preferred are those of Formula IIA-1 and IIA-2.

In the compounds of formulae IIA-1 to IIA-7, R ⁰ preferably represents an alkyl group having 1 to 6 C atoms, most preferably ethyl or propyl, and X ⁰ preferably represents F or OCF ₃ , most preferably F.

The proportion of the compound of the formula II in the LC medium is generally from 0 to 20% by weight, extremely preferably from 1 to 15% by weight and most preferably from 2 to 10% by weight.

In another preferred embodiment, the LC medium comprises one or more compounds of formula III selected from the following subformulae: wherein R ⁰ and X ⁰ have the meanings given in Formula II.

Preferred compounds are those of formula III-1, III-4, III-6, III-16, III-19 and III-20.

In the compounds of formulae III-1 to III-21, R ⁰ preferably represents an alkyl group having 1 to 6 C atoms, most preferably ethyl or propyl, X ⁰ preferably represents F or OCF ₃ , most preferably F, and Y ⁰ preferably represents H.

The LC medium may contain one or more compounds of formula III or its subformulae as described above and below, wherein ^Y0 is _CH3 . Very preferably, the medium according to this preferred embodiment comprises one or more compounds of formula III selected from the following subformulae: wherein R ⁰ and X ⁰ have the meanings given in Formula III.

Preferred compounds are those of Formula IIIA-1, IIIA-4, IIIA-6, IIIA-16, IIIA-19 and IIIA-20.

In the compounds of formulae IIIA-1 to IIIA-21, R ⁰ preferably represents an alkyl group having 1 to 6 C atoms, most preferably ethyl or propyl, X ⁰ preferably represents F or OCF ₃ , most preferably F, and Y ² preferably represents F.

The proportion of the compound of formula III in the LC medium is preferably 5 to 60% by weight, very preferably 10 to 50% by weight, most preferably 20 to 40% by weight.

In another preferred embodiment, the LC medium may additionally comprise one or more compounds selected from the following formulae: wherein R ⁰ , X ⁰ , L ^{1 - 4} and Y ⁰ have the meanings indicated in formulae II and III, Z ⁰ represents -C ₂ H ₄ -, -(CH ₂ ) ₄ -, -CH=CH-, -CF=CF-, -C ₂ F ₄ -, -CH ₂ CF ₂ -, -CF ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -COO-, -CF ₂ O- or -OCF ₂ -, which is also a single bond in formulae V and VI; and s represents 0 or 1.

The compound of formula IV is preferably selected from the following formula: wherein R ⁰ and X ⁰ have the meanings indicated in Formula II and III.

^R0 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F or _OCF3 , furthermore OCF= _CF2 or Cl.

The compound of formula Iva is preferably represented by the following subformula: The compound of formula IVb is preferably represented by the following formula: The compound of formula IVc is preferably represented by the following subformula: wherein R ⁰ has the meaning indicated in formula II and is preferably propyl or pentyl.

The compound of formula IVc, in particular the compound of formula IVc-1, is preferably used in the LC medium according to the invention in an amount of 1 to 20% by weight, particularly preferably 2 to 15% by weight.

The compound of formula V is preferably selected from the following sub-formulas: wherein R ⁰ and X ⁰ have the meanings indicated in Formula II.

^R0 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F and _OCF3 , furthermore _OCHF2 , _CF3 , OCF= _CF2 and OCH= _CF2 .

The compound of formula VI is preferably selected from the following sub-formulas: wherein R ⁰ and X ⁰ have the meanings indicated in Formula II.

^R0 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F, in addition to _OCF3 , _CF3 , CF= _CF2 , _OCHF2 and OCH= _CF2 ; The compound of formula VII is preferably selected from the following sub-formulae: wherein R ⁰ and X ⁰ have the meanings indicated in Formula II.

^R0 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F, and furthermore _OCF3 , _OCHF2 and OCH= _CF2 .

In some embodiments, the LC medium further comprises one or more compounds selected from the following formulae: wherein R ⁰ and X ⁰ each independently have one of the meanings indicated in formula II, L ^{1 - 4} each independently represent H or F, Y ⁰ represents H or CH ₃ , preferably H, X ⁰ is preferably F, Cl, CF ₃ , OCF ₃ or OCHF ₂ , R ⁰ preferably represents alkyl, alkoxy, oxyalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

Very preferably, the LC medium according to the invention comprises one or more compounds of formula XXa: wherein R ⁰ has the meaning indicated in formula LP1. R ⁰ preferably represents a linear alkyl group, in particular ethyl, n-propyl, n-butyl or n-pentyl and very particularly preferably n-propyl.

The compound of formula XX, in particular the compound of formula XXa, is preferably used in the LC medium according to the invention in an amount of 0 to 15% by weight, particularly preferably 1 to 10% by weight.

Very preferably, the LC medium according to the invention comprises one or more compounds of formula XXIa: wherein R ⁰ has the meaning indicated in formula LP1. R ⁰ preferably represents a linear alkyl group, in particular ethyl, n-propyl, n-butyl or n-pentyl and very particularly preferably n-propyl.

The compounds of the formula XXI, in particular the compounds of the formula XXIa, are preferably used in the LC media according to the invention in an amount of 1 to 15% by weight, particularly preferably 2 to 10% by weight.

Further preferably, the LC medium according to the invention comprises one or more compounds of formula XXIIIa: wherein R ⁰ has the meaning indicated in formula LP1. R ⁰ preferably represents a linear alkyl group, in particular ethyl, n-propyl, n-butyl or n-pentyl and very particularly preferably n-propyl.

The compound of formula XXIII, in particular the compound of formula XXIIIa, is preferably used in an amount of 0.5 to 5% by weight, particularly preferably 0.5 to 2% by weight, in the LC medium according to the invention.

The LC medium may additionally comprise one or more compounds of the formula XXIV: wherein R ⁰ , X ⁰ and L ^{1 - 6} have the meanings indicated in formula III, s represents 0 or 1, and .

In formula XXIV, ^X0 may also represent an alkyl group having 1 to 6 C atoms or an alkoxy group having 1 to 6 C atoms. The alkyl group or alkoxy group is preferably a straight chain.

R ⁰ preferably represents an alkyl group having 1 to 6 C atoms. X ⁰ preferably represents F; The compound of formula XXIV is preferably selected from the following sub-formulae: wherein R ⁰ , X ⁰ and L ¹ have the meanings indicated in formula III. R ⁰ preferably represents an alkyl group having 1 to 6 C atoms. ^{X 0} preferably represents F, and L ¹ is preferably F; R ⁰ is a linear alkyl or alkenyl group having 2 to 6 C atoms; The LC medium may further comprise one or more compounds of the following formulae: wherein ^R1 and ^X0 have the meanings indicated for ^R0 and ^X0 , respectively, in formula II. ^R1 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F or Cl. In formula XXIV, ^X0 very particularly preferably represents Cl.

The LC medium may further optionally contain one or more compounds of the following formula: wherein ^R1 and ^X0 have the meanings indicated for ^R0 and ^X0 , respectively, in formula II. ^R1 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F. The LC medium according to the invention particularly preferably comprises one or more compounds of the formula XXIX, wherein ^X0 preferably represents F.

The compounds of the formulae XXVI to XXIX are preferably used in the LC media according to the invention in an amount of 1 to 20% by weight, particularly preferably 1 to 15% by weight. Particularly preferred LC media comprise at least one compound of the formula XXIX.

Very preferably, the LC medium according to the invention comprises one or more compounds of formula XXIXa: wherein R ¹ has the meaning indicated in formula II and preferably represents a linear alkyl group, in particular ethyl, n-propyl, n-butyl or n-pentyl and very particularly preferably n-propyl.

The compound of the formula XXIXa is preferably used in the LC medium according to the invention in an amount of 1 to 15% by weight, particularly preferably 2 to 10% by weight.

The LC medium may further comprise one or more compounds of the following pyrimidine or pyridine compounds: wherein ^R1 and ^X0 have the meanings indicated for ^R0 and ^X0 , respectively, in formula II. ^R1 preferably represents an alkyl group having 1 to 6 C atoms. ^X0 preferably represents F. The medium according to the invention may in particular optionally comprise one or more compounds of the formula XXX-1, wherein ^X0 preferably represents F. The compounds of the formulae XXX-1 to XXX-3 can be used in the LC medium according to the invention in an amount of 1 to 20% by weight, particularly preferably 1 to 15% by weight.

Preferably, the LC medium contains, in addition to the compounds of formula I, LP1 and/or LP2, and optionally II and/or III, one or more compounds selected from the following formulae: Wherein "alkyl" and "alkyl*" are independently C _1-6 -alkyl, and preferably represent ethyl, propyl, butyl or pentyl, and most preferably ethyl, propyl or butyl. "alkenyl" and "alkenyl*" preferably represent C _2-6 -alkenyl. Compounds of formula Z1 and Z2 are particularly preferred.

Preferred compounds of formula Z1 to Z6 are those selected from the following subformulae:

In another preferred embodiment, the LC medium contains one or more compounds of formula Z1 or preferred subformulae thereof and/or one or more compounds selected from formulae Z2, Z3, Z4 and Z5 or preferred subformulae thereof.

Preferably, the total proportion of compounds of formula Z1, Z2, Z3, Z4, Z5 and Z6 or their subformulae (such as CC-3-V) in the medium is 10 to 65% by weight, very preferably 20 to 60% by weight, and most preferably 25 to 55% by weight. In a further preferred embodiment, the compound of formula Z1-1 is used in a concentration ranging from 10% to 60% by weight, more preferably 25% to 50% by weight, based on the total weight of the LC medium. In another preferred embodiment, the LC medium contains a total of 50% to 70% by weight of compounds represented by formula Z1-1 and Z4-2.

Preferably, the medium contains 1, 2 or 3 compounds selected from the group consisting of formula Z1, Z2, Z3 and Z4 or their subformulae.

The LC medium may additionally comprise one or more compounds of the following general formula: wherein R ¹ and R ² each independently represent C _1-6 -alkyl, C _1-6 -alkoxy or C _2-6 -alkenyl.

The compound of formula XII is preferably selected from the following sub-formulas: Here, "alkyl" and "alkyl*" each independently represent methyl, butyl, pentyl or hexyl.

Compounds of formula XIIa and XIIc are particularly preferred. In formula XIIb, "alkyl" preferably independently represents nC ₃ H ₇ , nC ₄ H ₉ or nC ₅ H ₁₁ , especially nC ₃ H ₇ . In formula XIIc, "alkyl" preferably represents nC ₃ H ₇ and "alkyl*" is preferably CH ₃ or nC ₃ H ₇ .

Particularly preferred compounds of formula XII are described by the following structure:

The LC medium may additionally comprise one or more compounds selected from the following formulae: wherein L ¹ and L ² have the meanings indicated in formula III, and R ¹ and R ² each independently represent n-alkyl, alkoxy, oxoalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and preferably each independently represent an alkyl group having 1 to 6 C atoms; in the compound of formula XIV, at least one of the substituents R ¹ and R ² preferably represents an alkenyl group having 2 to 6 C atoms.

In another preferred embodiment, the LC medium comprises one or more compounds of the following formula S: wherein the individual substituents have the following meanings: ^R1 and ^R2 are each independently H atom, alkyl or alkoxy having 1 to 12 C atoms, or alkenyl or alkenyloxy having 2 to 12 C atoms, wherein one or more non-adjacent _CH2 groups are optionally replaced by -C≡C-, _-CF2O- , _-OCF2- , -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- substituted in such a way that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, or a cycloalkyl group or cycloalkoxy group having 3 to 12 C atoms, in which one or more H atoms may be replaced by a halogen atom; R ³ H atom, an alkyl group having 1 to 3 C atoms or an alkenyl group having 2 to 3 C atoms, in which one or more non-adjacent CH ₂ groups are optionally substituted by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other; A ⁰ , A ¹ , A ² independently of one another denotes phenylene-1,4-diyl, in which, in addition, one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH ₃ , CHF ₂ , CH ₂ F, CF ₃ , OCH ₃ , OCHF ₂ or OCF ₃ ; cyclohexane-1,4-diyl, in which, in addition, one or two non-adjacent CH ₂ radicals may be independently replaced by O and/or S and one or more H atoms may be replaced by F; cyclohexene-1,4-diyl; bicyclo[1.1.1]pentane-1,3-diyl; bicyclo[2.2.2]octane-1,4-diyl; spiro[3.3]heptane-2,6-diyl; tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, Z ¹ and Z ² each independently represent -CF ₂ O-, -OCF ₂ -, -CH ₂ O-, -OCH ₂ -, -CO-O-, -O-CO-, -C ₂ H ₄ -, -C ₂ F ₄ -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ -, -CFHCFH-, -CFHCH ₂ -, -CH ₂ CFH-, -CF ₂ CFH-, -CFHCF ₂ -, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C≡C- or a single bond, k and l each independently represent 0, 1, 2 or 3.

Preferred are compounds of the formula S in which A ⁰ represents phenylene-1,4-diyl, in which, in addition, one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH ₃ , CHF ₂ , CH ₂ F, OCH ₃ , OCHF ₂ , CF ₃ or OCF _3. Particularly preferred are compounds in which A ⁰ represents , , , , or , better or And it is particularly good .

The presence of compounds of formula S results in LC media having particularly high bright spots, low rotational viscosity, broad nematic phase, high birefringence and very good thermal and UV stability.

Particularly preferred compounds of formula S are those selected from the following sub-formulae: wherein R ¹ , R ² and R ³ have the meanings indicated in the general formula S, and L ¹ to L ⁶ independently represent H or F. wherein R ¹ and R ² preferably represent an optionally fluorinated alkyl or alkoxy group having 1 to 12 C atoms, an optionally fluorinated alkenyl or alkynyl group having 2 to 12 C atoms, an optionally fluorinated cycloalkyl group having 3 to 12 C atoms, and R ³ preferably represents H or methyl.

Particularly preferred are optionally fluorinated alkyl, alkenyl or alkynyl groups having 1 to 5 C atoms. ^L2 in formulae S-1-1 to S-1-6 preferably represents F. In formulae S-1-4 to S-1-6, ^L3 and ^L4 preferably represent H. In said formulae S-1-4 to S-1-6, said ^L3 and ^L4 preferably represent F.

In a particularly preferred embodiment, the compound of formula S is represented by the following structure: wherein R ¹ and R ² independently represent a straight or branched chain alkyl or alkoxy group having 1 to 7 C atoms, or an alkenyl, alkenyloxy, alkoxyalkyl group having 1 to 7 C atoms, or a cycloalkyl or cycloalkoxy group having 3 to 12 C atoms, wherein one or more non-adjacent CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- are substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, wherein one or more H atoms may be replaced by a halogen atom; R ³ represents an H atom, an alkyl group having 1 to 3 C atoms or an alkenyl group having 2 to 3 C atoms, preferably an H atom or a methyl group; and L ¹ and L ² independently represent an H atom or F, preferably F.

The LC medium may further optionally comprise one or more compounds of the formula XIV, in which at least one of the substituents R ¹ and R ² represents an alkenyl group having 2 to 6 C atoms, preferably they are selected from the following subformulae: Wherein "alkyl" and "alkyl*" have the meanings indicated above, and each independently preferably represents methyl, ethyl or propyl.

The compound of formula XIV is preferably selected from the following sub-formulas: Particularly preferred are compounds of formula XIVd-1, XIVe-1, XIVe-2 and XIVe-3.

In yet another embodiment, the LC medium comprises one or more compounds of formula XVI: wherein ^R1 and ^R2 have the meanings indicated in formula I and LP1, respectively, and preferably each independently represent an alkyl group having 1 to 6 C atoms. L represents H or F.

Particularly preferred compounds of formula XVI are those of the following subformulae: wherein "alkyl" and "alkyl*" each independently represent a straight-chain alkyl group having 1 to 6 C atoms, in particular ethyl, propyl or pentyl, and "alkenyl" and "alkenyl*" each independently represent a straight- _chain alkenyl group having 2 to 6 C atoms, in particular _CH2 = _CHC2H4 , _CH3CH = _CHC2H4 , _CH2 =CH _{and CH3CH} =CH.

Particularly preferred are compounds of the formulae XVIb and XVIc. Very particularly preferred are compounds of the following sub-formulae: The most preferred is the compound of formula XVIc-2.

The LC medium may optionally contain one or more compounds of the following formula: wherein ^R1 and ^R2 have the meanings indicated in formula I and LP1, respectively, and preferably each independently represent an alkyl group having 1 to 6 C atoms. L represents H or F.

Very preferred are compounds of formula XVIIa, wherein L is H. Very preferred are compounds of formula XVIIb, wherein L is F.

The LC medium may additionally comprise one or more compounds of the formula: wherein L, ^R1 and ^R2 have the meanings indicated for ^Y1 , ^R0 and ^R2 in formula LP1, respectively. ^R1 and ^R2 preferably represent alkyl, alkoxy, oxoalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

In some other embodiments, the medium comprises one or more compounds of the formula: wherein R ¹ and R ² have the meanings indicated in formula I and LP1, respectively, and preferably each independently represent an alkyl group having 1 to 6 C atoms.

In a preferred embodiment according to the present invention, in addition to the compounds of formula I, LP1 and/or LP2, II and/or III, the LC medium also contains one or more compounds selected from the group consisting of formula Y and B: wherein the individual substituents have the following meanings on each occurrence, identically or differently and independently of one another: R ¹ and R ² have one of the meanings given for R ¹¹ and R ¹² in formula I, R ³ has one of the meanings given for R ¹ , Z ^x , Z ^y -CH ₂ CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, -CH ₂ O-, -OCH ₂ -, -CO-O-, -O-CO-, -C ₂ F ₄ -, -CF=CF-, -CH=CH-CH ₂ O- or a single bond, preferably a single bond, Z ^z -CH ₂ O-, -O-, -C ₂ H ₄ -, -OCH ₂ - or a single bond, Y ¹ -CH ₂ -, -O- or -S-, L ^{1 - 4} H, F or Cl, preferably H or F, most preferably F, x, y 0, 1 or 2, and x+y ≤ 3, z 0 or 1, wherein in formula B, the dibenzofuran or dibenzothiophene group may be further substituted by a methyl or methoxy group, and wherein the compound of formula Y contains at least one substituent L ^{1 - 4} which is F or Cl, preferably F.

Preferably, the LC medium according to this first preferred embodiment contains one or more compounds of formula I, LP1 and/or LP2, II and/or III, one or more compounds selected from formula Z1, Z2 and Z3, and one or more compounds selected from formula Y and B.

The LC medium according to this first preferred embodiment is particularly suitable for use in LC displays in HB-FFS or PS-HB-FFS mode.

In the compounds of formula Y and its subformulae, ^R1 and ^R2 preferably represent straight-chain alkyl or alkoxy having 1 to 6 C atoms, furthermore alkenyl having 2 to 6 C atoms, in particular vinyl, 1E-propenyl, 1E-butenyl, 3-butenyl, 1E-pentenyl, 3E-pentenyl or 4-pentenyl.

In the compounds of formula Y and its subformulae, preferably both substituents L ¹ and L ² represent F. In another preferred embodiment of the present invention, in the compounds of formula Y and its subformulae, one of the substituents L ¹ and L ² represents F and the other represents Cl.

In a preferred embodiment of the invention, the LC medium contains one or more compounds of formula Y selected from the following subformulae: wherein ^L1 , ^L2 , R1, ^R2 , ^Zx , ^Zy , x and y have the meanings given in formula Y or one of the preferred meanings given above in formula I. a represents 1 or 2, b represents 0 or 1, ^L1 , ^{L2 represent} F or Cl, preferably F, and ^L5 represents an H atom or _CH3 , Preferably, in the compounds of formula ^Y1 and ^Y2 , ^L1 and ^L2 both represent F or one of ^L1 and ^L2 represents F and the other represents Cl, or ^L1 and ^L2 both represent F or one of ^L1 and ^L2 represents F and the other represents Cl.

Preferably, the LC medium comprises one or more compounds of formula Y1 selected from the group consisting of the following subformulae: wherein a represents 1 or 2, "alkyl" and "alkyl*" each independently represent a straight-chain alkyl group having 1 to 6 C atoms, "alkenyl" represents a straight-chain alkenyl group having 2 to 6 C atoms _, and ^L5 represents an H atom or _CH3 . "Alkenyl" preferably represents _CH2 =CH-, _CH2 = _CHCH2CH2- , _CH3- CH= _CH- , CH3 _{- CH2} -CH=CH-, CH3-( _CH2 ) _{2 -} CH=CH-, CH3-( _CH2 ) ₃ -CH=CH- or _CH3 -CH=CH-( _CH2 ) _2- .

Most preferably, the LC medium contains one or more compounds of formula Y1 selected from the group consisting of formula Y1-1, Y1-2, Y1-7, Y1-12, Y1-17, Y1-22, Y1-40, Y1-41, Y1-42, Y1-44, Y1-50 and Y1-68. ^L5 preferably represents an H atom.

Further preferably, the LC medium comprises one or more compounds of formula Y2 selected from the group consisting of the following subformulae: wherein "alkyl" and "alkyl*" each independently represent a straight chain alkyl group having 1 to 6 C atoms, and "alkenyl" represents a straight chain alkenyl group having 2 to 6 C atoms, (O) represents an oxygen atom or a single bond, and L ⁵ represents a H atom or CH ₃ , preferably a H atom.

"Alkenyl" preferably represents CH ₂ =CH-, CH ₂ =CHCH ₂ CH ₂ -, CH ₃ -CH=CH-, CH ₃ -CH ₂ -CH=CH-, CH ₃ -(CH ₂ ) ₂ -CH =CH-, CH ₃ -(CH ₂ ) ₃ -CH=CH- or CH ₃ -CH=CH-(CH ₂ ) ₂ -.

Most preferably, the LC medium contains one or more compounds of formula Y2 selected from formula Y2-2 and Y2-10.

The proportion of compounds of the formula Y1 or its subformulae in the LC medium is preferably from 0 to 10% by weight.

The proportion of compounds of the formula Y2 or its subformulae in the LC medium is preferably from 0 to 10% by weight.

The total proportion of the compounds of formula Y1 and Y2 or their subformulae in the medium is preferably 1 to 20% by weight, and most preferably 2 to 15% by weight.

Preferably, the LC medium contains 1, 2 or 3 compounds of formula Y1 and Y2 or their subformulae, most preferably selected from the compounds of formula Y1-2, Y1-22, Y1-66, Y1-70, Y2-6 and Y2-22.

In another preferred embodiment of the invention, the LC medium contains one or more compounds of formula Y of the following subformulae: wherein L ¹ , L ² , R ¹ and R ² have one of the meanings given in formula Y or one of the preferred meanings given in formula I, LP1 and LP2.

Preferred compounds of formula Y3 are selected from the group consisting of the following subformulae: Wherein, "alkyl" and "alkyl*" each independently represent a straight-chain alkyl group having 1 to 6 C atoms; "alkenyl" and "alkenyl*" each independently represent a straight-chain alkenyl group having 2 to 6 C atoms; and (O) represents an oxygen atom or a single bond.

"Alkenyl" and "alkenyl*" preferably represent _CH2 =CH-, _CH2 = _{CHCH2CH2- , CH3-} CH=CH-, CH3 _-CH2 - _CH =CH-, CH3-( _CH2 ) ₂ -CH=CH-, _CH3- ( _CH2 ) _{3 -} CH=CH- or _CH3 -CH=CH-( _CH2 ) _2- . Particularly preferred compounds of formula Y3 are selected from the group consisting of the following subformulae: Wherein "alkoxy" and "alkoxy*" each independently preferably represent a straight-chain alkoxy group having 3, 4 or 5 C atoms.

Preferably, in compounds of formula Y3 and subformulae thereof, both ^L1 and ^L2 represent F. Further preferably, in compounds of formula Y3, one of the substituents ^L1 and ^L2 represents F and the other represents Cl.

The proportion of compounds of the formula Y3 or subformulae thereof in the LC medium is preferably from 0 to 10% by weight, very preferably from 1 to 6% by weight.

Preferably, the LC medium contains 1, 2 or 3 compounds of formula Y3 or its subformulae, more preferably compounds of formula Y3-6, most preferably compounds of formula Y3-6A.

In yet another preferred embodiment of the present invention, the LC medium contains one or more compounds of formula Y of sub-formula Y4: wherein R ¹ and R ² each independently have one of the meanings indicated above in formula Y, and Each independently expresses wherein L ⁵ represents F or Cl, preferably F, and L ⁶ represents F, Cl, OCF ₃ , CF ₃ , CH ₃ , CH ₂ F or CHF ₂ , preferably F, and preferably at least one of rings G, I and K is different from unsubstituted benzene.

The most preferred compounds of formula Y4 are selected from the group consisting of the following subformulae: wherein R represents a straight-chain alkyl or alkoxy group having 1 to 7 C atoms, R* represents a straight-chain alkenyl group having 2 to 7 C atoms, (O) represents an oxygen atom or a single _{bond, and m represents an integer of 1 to 6. R* preferably represents CH2=CH-, CH2=CHCH2CH2- , CH3 - CH} =CH-, _CH3 - _CH2 -CH=CH-, _CH3- ( _CH2 ) ₂ -CH=CH-, _CH3- ( _CH2 ) ₃ -CH=CH- or _CH3 -CH=CH-( _CH2 ) _2- .

R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentyloxy.

The proportion of the compound of formula Y4 or its subformula in the medium is preferably 0 to 10% by weight, and most preferably 1 to 6% by weight.

Particularly preferred compounds are those of the following subformula: Here, "alkyl" and "alkyl*" each independently represent a straight-chain alkyl group having 1 to 6 C atoms, in particular ethyl, propyl or pentyl.

The following compounds are particularly advantageously used: In another preferred embodiment of the present invention, the LC medium contains one or more compounds of formula Y selected from the group consisting of the following subformulae: wherein R ⁵ has one of the meanings indicated for R ¹ in formula Y, "alkyl" represents a linear alkyl group having 1 to 6 C atoms, L ^x represents H or F, d represents 0 or 1, and z and m each independently represent an integer of 1 to 6.

R ⁵ in these compounds is particularly preferably C _2-6 -alkyl or -alkoxy or C _2-6 -alkenyl, and d is preferably 1. The LC medium according to the invention preferably comprises one or more compounds of the above-mentioned formulae in an amount of ≥ 5% by weight.

Further preferred embodiments are indicated below: - The LC medium comprises one or more compounds of formula Y of the following subformulae: wherein R ¹ , R ² , L ¹ , L ² , X, x and Z ^x have the meanings given in formula Y, and wherein at least one of the rings X is cyclohexenyl.

Preferably, both substituents L ¹ and L ² represent F. Further preferably, one of the substituents L ¹ and L ² represents F and the other represents Cl.

The compound of formula LY is preferably selected from the group consisting of the following subformulae: wherein R ¹ has the meaning indicated above in formula Y, (O) represents an oxygen atom or a single bond, and v represents an integer from 1 to 6. R ¹ preferably represents a straight-chain alkyl group having 1 to 6 C atoms or a straight-chain alkenyl group having 2 to 6 C atoms, in particular CH ₃ , C ₂ H _{5 ,} nC ₃ H ₇ , nC ₄ H ₉ , nC ₅ H ₁₁ , CH ₂ ═CH—, CH ₂ ═CHCH ₂ CH ₂ —, CH ₃ —CH═CH—, _CH 3 —CH 2 —CH═CH—, CH ₃ —(CH ₂ ) ₂ —CH═CH—, CH ₃ —(CH ₂ ) ₃ —CH═CH— or CH ₃ —CH═CH—(CH ₂ ) ₂ —.

The most preferred compound is the compound of formula LY4.

Preferably, the medium contains 1, 2 or 3 compounds of formula LY, most preferably compounds of formula LY4.

The proportion of the compound of formula LY or its sub-formula in the medium is preferably 1 to 10% by weight.

- The medium comprises one or more compounds of formula Y represented by the following sub-formula: wherein R ¹ , R ² , L ¹ , L ² , Y, y and Z ^y have the meanings given in formula Y, and wherein at least one of the rings Y is tetrahydropyran.

The compound of formula AY is preferably selected from the group consisting of the following subformulae: wherein R ¹ has the meaning indicated above, "alkyl" represents a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, and v represents an integer from 1 to 6. _R ¹ preferably represents a straight-chain alkyl group having 1 to 6 C atoms or a straight-chain alkenyl group having 2 to 6 C atoms, in particular CH ₃ , C ₂ H ₅ , nC ₃ H ₇ , nC ₄ H ₉ , nC ₅ H ₁₁ , CH 2 ═CH—, CH ₂ ═CHCH ₂ CH ₂ —, CH ₃ —CH═CH—, CH _{3 —CH 2} —CH═CH—, CH ₃ —(CH ₂ ) ₂ —CH═CH—, CH 3 —(CH ₂ ) ₃ —CH═CH— or CH ₃ —CH═CH—(CH ₂ ) ₂ —.

In the compounds of formula B and its subformulae, R ¹ and R ³ preferably represent straight-chain alkyl or alkoxy having 1 to 6 C atoms, in particular methoxy, ethoxy, propoxy or butoxy, furthermore alkenyl having 2 to 6 C atoms, in particular vinyl, 1E-propenyl, 1E-butenyl, 3-butenyl, 1E-pentenyl, 3E-pentenyl or 4-pentenyl.

In a preferred embodiment of the present invention, the medium contains one or more compounds of formula B selected from the following sub-formulas: wherein L ¹ , L ² , R ¹ and R ³ have the meanings given in formula B. Preferred compounds of formula B1 are selected from the following sub-formulas: wherein R ¹ and R ³ independently represent a straight chain alkyl group having 1 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms may be replaced by a halogen atom.

Most preferred are compounds of formula B1-1 and B1-2, wherein both groups (O) represent oxygen atoms and ^R1 and ^R3 independently represent alkyl groups, which are methyl, ethyl, propyl, butyl, pentyl or hexyl, preferably in a straight chain. Most preferably, one "alkyl" is ethyl and the other "alkyl*" is n-pentyl.

Particularly preferred are compounds of formula B1-2.

Preferably, the compound of formula B1-1 is selected from the group consisting of compounds of formula B1-1-1 to B1-1-11, preferably the compound of formula B1-1-6: "alkyl" and "alkyl*" each independently represent a straight-chain alkyl group having 1 to 6 C atoms, "alkenyl" and "alkenyl*" each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, and "alkoxy" and "alkoxy*" each independently represent a straight-chain alkoxy group having 1 to 6 C atoms.

Preferably, the compound of formula B1-2 is selected from the group consisting of compounds of formula B1-2-1 to B1-2-10, preferably the compound of formula B1-2-6: "alkyl" and "alkyl*" each independently represent a straight-chain alkyl group having 1 to 6 C atoms, "alkenyl" and "alkenyl*" each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, and "alkoxy" and "alkoxy*" each independently represent a straight-chain alkoxy group having 1 to 6 C atoms.

Optionally, the LC medium comprises one or more compounds of formula B1-1A and/or B1-2A: wherein (O) denotes O or a single bond, R ^IIIA denotes an alkyl or alkenyl group having up to 7 C atoms or a group Cy-C _m H _2m+1 -, m and n are identically or differently 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, which is optionally substituted by alkyl or alkenyl groups each having up to 3 C atoms, or by halogen or CN, and preferably denotes cyclopropyl, cyclobutyl or cyclopentyl.

Instead of or in addition to the compounds of formula B1-1 and B1-2, preferably in addition to them, the medium also contains a compound of formula B1-1A and/or B1-2A.

Preferred compounds of formula B1-1A and/or B1-2A are also as follows: Wherein alkoxy represents a straight chain alkoxy group having 1 to 6 C atoms or -(CH ₂ ) _n F, wherein n is 2, 3, 4 or 5, preferably C ₂ H ₄ F.

The proportion of compounds of the formula B1 or its subformulae in the LC medium is preferably 1 to 20% by weight, very preferably 1 to 15% by weight.

Preferably, the LC medium contains 1, 2 or 3 compounds of formula B1 or subformulae thereof.

In a preferred embodiment of the present invention, the LC medium may comprise one or more compounds of formula B2-2 wherein R ¹ and R ³ are identical or different and represent H, an alkyl group or an alkoxy group having 1 to 6 carbon atoms, wherein one or more CH ₂ groups in these groups are optionally independently replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly connected to one another and wherein, in addition, one or more H atoms may be replaced by a halogen.

The compound of formula B2-2 is preferably selected from the group consisting of compounds of formula B2-2-1 to B2-2-10: wherein R ³ represents an alkyl group having 1 to 6 C atoms, preferably ethyl, n-propyl or n-butyl, or cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or -(CH ₂ ) _n F, wherein n is 2, 3, 4 or 5, preferably C ₂ H ₄ F.

Particularly preferred compounds of formula B2 are selected from the following sub-formulae:

The proportion of compounds of the formula B2 or its subformulae in the LC medium is preferably 1 to 20% by weight, very preferably 1 to 15% by weight.

Preferably, the LC medium contains 1, 2 or 3 compounds of formula B2 or subformulae thereof.

Preferred compounds of formula B3 are selected from the following subformulae: wherein R ¹ has one of the meanings given in formula B3 and preferably represents linear alkyl having 1 to 6 C atoms, very preferably methyl, ethyl, propyl, butyl, pentyl or hexyl, more preferably ethyl or propyl, most preferably propyl, and X ¹ has one of the meanings given in formula B3 and preferably represents CF ₃ or OCF ₃ .

Preferred compounds of formula B3 are selected from the following subformulae: wherein R ¹ has one of the meanings given in formula B3 and preferably represents a straight-chain alkyl group having 1 to 6 C atoms, very preferably methyl, ethyl, propyl, butyl, pentyl or hexyl, more preferably ethyl or propyl, most preferably propyl.

The most preferred are compounds of formula B3-1-1 and B3-2-2.

In a preferred embodiment, the LC medium contains one or more compounds of formula B or its subformulae B1, B2, B3, B1-1, B1-2, B2-1, B2-2, B2-3, B3-1, B3-2, B3-1-1, B3-1-2, B3-2-1 and B3-2-2, wherein the dibenzofuran or dibenzothiophenyl group is substituted by a methyl or methoxy group, preferably by a methyl group, preferably in the para position to the substituent F, very preferably in the para position to the substituent F (i.e. in the meta position to the terminal group ^R or ^X ).

The proportion of compounds of the formula B3 or its subformulae in the LC medium is preferably 1 to 20% by weight, very preferably 1 to 10% by weight.

Preferably, the LC medium contains 1, 2 or 3 compounds of formula B3 or subformulae thereof.

Preferably, the total proportion of compounds of the formulae Y and B or their subformulae in the LC medium is 2 to 25% by weight, particularly preferably 3 to 20% by weight.

In some preferred embodiments of the present invention, the LC medium may further comprise one or more compounds of the general formula ST: wherein the individual substituents have the following meanings: express , or ; X ²¹ and X ²² each independently represent -O-, -CH ₂ -, -CHR ₂₃ - or -NR ₂₃ -, R ²¹ and R ²² each independently represent an H atom or an alkyl or alkoxy group having 1 to 12 C atoms, an alkenyl, alkynyl, alkenyloxy or alkoxyalkyl group having 2 to 12 C atoms, or a cycloalkyl group having 3 to 12 C atoms, wherein one or more non-adjacent CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, or a cycloalkyl group or cycloalkoxy group having 3 to 12 C atoms, and one or more H atoms thereof may be replaced by a halogen atom, R ²³ represents an H atom, an alkyl group or alkoxy group having 1 to 10 C atoms, and r represents 0 or 1.

LC media comprising compounds of the following subformulae ST-1, ST-2 and ST-3 show particularly high long-term thermal and UV stability: The individual substituents have the following meanings: express , or ; R ²¹ and R ²² each independently represent an H atom or an alkyl or alkoxy group having 1 to 7 C atoms, and r represents 0 or 1.

In a particularly preferred embodiment, the compound of formula ST can be selected from the following specific structures:

In another preferred embodiment, the LC medium according to the present invention may comprise at least one additional sterically hindered phenol, which are mentioned in Table B below.

Compounds of Formula H The LC medium may optionally contain one or more compounds of Formula H wherein R ¹¹ each independently represents an H atom, F, an alkyl group having 1 to 20 C atoms, wherein one -CH ₂ - group or (if present) a plurality of -CH ₂ - groups may be replaced by -O- or -C(=O)-, but two adjacent -CH ₂ - groups cannot be replaced by -O-, and one or (if present) a plurality of -CH 2 - groups may be replaced by -CH=CH- or -C≡C-, and wherein one or a plurality of H atoms may be replaced by F, OR ¹³ , N(R ¹³ )(R ¹⁴ ) or R 15, R ¹² each independently represents an H atom, an alkyl group having 1 to 20 C atoms, wherein one or a plurality of -CH ₂ - groups may be replaced by -O- or -C(=O)-, but two adjacent -CH ² - groups cannot be replaced by -O-, and one or (if present) a plurality of -CH ₂ - groups may be replaced by -CH=CH- or -C≡C-, and wherein one or a plurality of _H atoms may be replaced by F, OR 13 , N(R 13 )(R 14 ) or R ₁₅ -group cannot be replaced by -O-, a cycloalkyl or alkylcycloalkyl unit-containing alkyl group in which one or more -CH ₂ -groups can be replaced by -O- or -C(=O)-, but two adjacent -CH ₂ -groups cannot be replaced by _-O- , and one or more H atoms can be replaced by F, OR ¹³ , N(R ¹³ )(R ¹⁴ ) or R ¹⁵ , or an aromatic or heteroaromatic alkyl group in which one or more H atoms can be replaced by OR ¹³ , N(R ¹³ )(R ¹⁴ ) or R ¹⁵ , R ¹³ and R ¹⁴ each independently represent an alkyl or acyl group having 1 to 10 C atoms or an aromatic alkyl group having 6 to 12 C atoms or a carboxylic acid group, R ^{R 15} each independently represents an alkyl group having 1 to 10 C atoms, wherein one -CH ₂ - group or multiple -CH ₂ - groups may be replaced by -O- or -C(=O)-, but two adjacent -CH ₂ - groups may not be replaced by -O-, R ¹⁶ each independently represents an H atom, an alkyl group or alkoxy group having 1 to 10 C atoms, an O-cycloalkyl group having 3 to 12 C atoms, O ^• or OH, S ¹¹ and S ¹² each independently represent an alkylene group having 1 to 20 C atoms, wherein one -CH ₂ - group or (if present) multiple -CH ₂ - groups may be replaced by -O- or -C(=O)-, but two adjacent -CH ₂ - groups may not be replaced by -O-, and wherein one H atom or multiple H atoms may be replaced by F, OR ¹³ , N(R ¹³ )(R ¹⁴ ) or R ¹⁵ is substituted, or represents a single bond. Y ¹¹ to Y ¹⁴ each independently represent methyl or ethyl, X ¹¹ represents C, Z ¹¹ to Z ¹⁴ each independently represent -O-, -(C=O)-, -O-(C=O)-, -(C=O)-O-, -O-(C=O)-O-, -(NR ¹³ )-, -NR ¹³ -(C=O)- or a single bond, if S ¹¹ is a single bond, then both Z ¹¹ and Z ¹² do not simultaneously represent -O-; if S ¹² is a single bond, then both Z ¹³ and Z ¹⁴ do not simultaneously represent -O-; and if q represents 0, then both Z ¹² and Z ¹³ do not simultaneously represent -O-, p represents 1 or 2, q represents 0 or 1, o represents (3-p), n represents an integer from 1 to 10, m represents an integer from 0 to 8, wherein n * p represents an integer from 1 to 10, preferably from 3 to 8, and represents an organic moiety having (m+n) bonding sites. In some preferred embodiments of the present invention, in the compound of formula H, express , (biphenyl-1,1´,3,3´-tetrayl) or (Benzene-1,2,4,5-tetrayl) express (Benzene-1,3,5-triyl) or (Benzene-1,2,4-triyl), represents -(CH ₂ -) ₂ , -(CH ₂ -) ₃ , -(CH ₂ -) ₄ , -(CH ₂ -) ₅ , -(CH ₂ -) ₆ , -(CH ₂ -) ₇ , -(CH ₂ -) ₈ , that is 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), (1,3-phenylene), (1,2-phenylene) or (trans-1,4-cyclohexylene) and/or wherein -Z ¹² -S ¹¹ -Z ¹¹ - independently at each occurrence represents -O-, S ¹¹ -O-, -OS ¹¹ -O-, -(C=O)-OS ¹¹ -O-, -O-(C=O)-S ¹¹ -O-, -O-(C=O)-S ¹¹ -(C=O)-O-, -OS ¹¹ -(C=O)-O-, -(C=O)-OS ¹¹ -C, -(C=O)-OS ¹¹ -O-(C=O)-, or -(NR ¹³ )-S ¹¹ -O-, -(NR ¹³ -C(=O)-S ¹¹ -(C=O)-O or a single bond, preferably -O-, -S ¹¹ -O-, -OS ¹¹ -O-, -(C=O)-OS ¹¹ -O-, -O-(C=O)-S ¹¹ -O- or -OS ¹¹ -(C=O)-O-, and/or S ¹¹ preferably represents an alkylene group having 1 to 20 C atoms, and/or R ¹¹ , if present, represents alkyl, alkoxy or H, preferably H or alkyl, and/or R ¹² represents H, methyl, ethyl, propyl, isopropyl or 3-heptyl or cyclohexyl.

In a preferred embodiment of the present application, in the compound of formula H, represents a group selected from the following groups: , , , , , or In another preferred embodiment of the present application, in the compound of formula H, represents a group selected from the following groups: , or .

In yet another preferred embodiment of the present invention, in the compound of formula H, wherein p preferably represents 1, express , preferably -OS ¹¹ -O-, -S ¹¹ -O- or -OS ¹¹ -, particularly preferably -OS ¹¹ -O- or -S ¹¹ -O-.

In another preferred embodiment of the present invention, in the compound of formula H, the group represents a group selected from the following groups: , , , or . In another preferred embodiment of the present invention, wherein p is 2, which may be the same as or different from those described above, in the compound of formula H, represents a group selected from the following groups: , and .

In yet another preferred embodiment of the present invention, which may be the same as or different from those described above, in the compound of formula H, the group , Each occurrence indicates independently , , or , Better or .

The compounds of the following general formulae H-1-1, H-1-2 and H-1-3 were shown to be particularly efficient UV stabilizers in LC mixtures, in particular, in terms of VHR stability: wherein ZG, R ¹⁶ and n are as defined above and n represents an integer from 1 to 8. These compounds are very suitable as stabilizers in LC mixtures and stabilize the VHR of these mixtures upon UV exposure.

In a particularly preferred embodiment, one or more compounds of formula H can be selected from the group consisting of compounds of formula H-2-1 to H-2-6: wherein R ¹¹ each independently represents an H atom, an alkyl group having 1 to 20 C atoms, wherein one -CH ₂ - group or (if present) a plurality of -CH ₂ - groups may be replaced by -O- or -C(=O)-, but two adjacent -CH ₂ - groups cannot be replaced by -O-, and one or (if present) a plurality of -CH ₂ - groups may be replaced by -CH=CH- or -C≡C-, and wherein one or a plurality of H atoms may be replaced by F, OR ¹³ , N(R ¹³ )(R ¹⁴ ) or R 15, R 16 represents an H atom or O ^• , n represents an integer from 0 to 12, and S 11 and S ¹² each independently represent an alkylene group having 1 to 20 C atoms, wherein one -CH 2 - group or (if present) a plurality of -CH 2 - groups may be replaced by -O- or -C(=O)-, but two adjacent -CH 2 ^- groups may not be replaced by -O-, and one or (if present) a plurality of -CH ₂ - groups may be replaced by -CH=CH- or ^-C≡C- , and wherein one or a plurality of H atoms may be replaced by F, OR ¹³ , N(R 13 )(R 14 ) or R ₁₅ -group may be replaced by -O- or -C(=O)-, but two adjacent -CH ₂ -groups cannot be replaced by -O-, and one or more H atoms may be replaced by F, OR ¹³ , N(R ¹³ )(R ¹⁴ ) or R ¹⁵ , or represent a single bond.

In a preferred embodiment of the invention, the LC medium according to the invention comprises in each case one or more compounds of the formula H selected from the group of compounds of the following formulae: and

The preferred content of one or more compounds of the formula H in the LC medium depends inter alia on the intrinsic chemical stability of the LC medium and on the nature of the compounds of the formula H. Compounds of the formula H in which R ¹⁶ represents O· (so-called NO-group-type HALS) are preferably used in a proportion in the range of 50 ppm to 1000 ppm, based on the weight of the LC medium. Compounds of the formula H in which R ¹⁶ represents an H atom (so-called NH-group-type HALS) are advantageously used in a proportion in the range of 50 ppm to 2000 ppm, based on the weight of the LC medium.

Other preferred LC media are selected from the following preferred embodiments, including any combination thereof: Ÿ Combination of a compound of formula I with a compound of formula LP1, Z1 to Z7 and II and/or III Ÿ Combination of a compound of formula I with a compound of formula LP2, Z1 to Z7 and II and/or III Ÿ Combination of a compound of formula I with a compound of formula LP1, LP2, II and/or III and a compound of formula Z1 and Z4 - The LC medium comprises one or more compounds of formula I or its subformulae and LP1 and/or LP2, II and/or III and one or more compounds selected from the group consisting of formula Z1, Z2, Z3, Z4, Z5, V, VI, VII, VIII, XIV, XV, XVI, XVIIa, XVIIb, XVIIc, XVIII, XIX, XX, XXI, XXIII, XXIV, XXV, XXVI, XXVII, XXVIII, XXIX, XXX, XXX-1, XXX-2, XXX-3, XXXI, XXXII, XXXIII and S and their subformulae. - The LC medium comprises one or more compounds of formula I or its subformulae and LP1 and/or LP2, II and/or III and one or more compounds selected from the group consisting of formula Z1, Z2, Z3, Z4, Z5, IV, VI, XII, XIV, XVI, XVIIa, XVIIb, XVIIc, XX, LP1-1, XXIII, XXIX, XXXI and S and their subformulae. - The LC medium comprises one or more compounds selected from the group consisting of formulae II-1, II-2 and II-3, preferably selected from formulae II-1 and II-2. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 25% by weight. - The LC medium comprises one or more compounds selected from the group consisting of formula III-1, III-4, III-6, III-16, III-19 and III-20, preferably selected from the group consisting of formula III-1, III-6, III-16 and III-20. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 30% by weight. - The LC medium comprises one or more compounds of formula IV, preferably selected from formula IVa or IVc, preferably selected from formula IVa-1 or IVc-1, most preferably a compound of formula IVc-1. The individual concentration of each of these compounds is preferably 2 to 15% by weight. The total concentration of these compounds is preferably 5 to 20% by weight. - The LC medium comprises one or more compounds of formula VI, preferably selected from formula VIb. The individual concentration of each of these compounds is preferably 1 to 20% by weight. The total concentration of these compounds is preferably 5 to 20% by weight. - The LC medium comprises one or more compounds of formula Z1, preferably selected from formula Z1-1. The total concentration of these compounds is preferably 1 to 60% by weight, more preferably 5 to 50% by weight. - The LC medium comprises one or more compounds of formula Z2, preferably selected from formula Z2-1 and Z2-2. The total concentration of these compounds is preferably 2 to 35% by weight, very preferably 3 to 25% by weight. - The LC medium comprises 5 to 20% by weight of a compound of formula Z3, preferably a compound of formula Z3-1. - The LC medium comprises 5 to 20% by weight of a compound of formula Z4, preferably a compound of formula Z4-1. - The LC medium comprises 10 to 65% by weight, particularly 20 to 60% by weight of a compound of formula Z5. - The LC medium comprises one or more compounds of formula LP1-1, particularly LP1-1a or LP2-1b, particularly LP1-1a. The concentration of these compounds is preferably 2 to 15% by weight. - The LC medium comprises 1 to 15% by weight of a compound of formula LP2-1b. - The LC medium comprises one or more compounds of formula XII, particularly XIIa or XIIb, particularly XIIa, particularly XIIa-1. The concentration of these compounds is preferably 2 to 15% by weight. - The LC medium comprises 1 to 15 wt.% of a compound of formula XIIb. - The LC medium comprises one or more compounds of formula XIV, preferably compounds of formula XIVd, most preferably compounds of formula XIVd-1. The concentration of these compounds is preferably 2 to 10 wt.%. - The LC medium comprises one or more compounds of formula XVIb, preferably compounds of formula XVIb-1, XVIb-2 and/or XVIb-3. The concentration of these compounds is preferably 2 to 15 wt.%. - The LC medium comprises one or more compounds of formula XVIc, preferably compounds of formula XVIc-1, XVIc-2 and/or XVIc-3. The concentration of these compounds is preferably 2 to 20 wt.%. - The LC medium comprises one or more compounds selected from the group consisting of formulae XVIIa, XVIIb and XVIIc, preferably compounds of formula XVIIa, wherein L is H, and compounds of formula XVIIb, wherein L is F. The total concentration of these compounds is preferably 0.5 to 5% by weight. - The LC medium comprises one or more compounds of formula XX, preferably compounds of formula XXa. The concentration of these compounds is preferably 2 to 10% by weight. - The LC medium comprises one or more compounds of formula XXI, preferably compounds of formula XXIa. The concentration of these compounds is preferably 2 to 10% by weight. - The LC medium comprises one or more compounds of formula XXIII, preferably compounds of formula XXIIIa. The concentration of these compounds is preferably 0.5 to 5% by weight. - The LC medium comprises one or more compounds of the formula XXIX, preferably compounds of the formula XXIXa. The concentration of these compounds is preferably 2 to 10% by weight. - The LC medium comprises one or more compounds of the formula XXX. The concentration of these compounds is preferably 2 to 10% by weight. - The LC medium comprises one or more compounds of the formula XXXI. The concentration of these compounds is preferably 2 to 10% by weight. - The LC medium comprises one or more compounds of the formula S, preferably compounds of the formula S-1-4-1. The concentration of these compounds is preferably 1 to 25% by weight. - The LC medium comprises one or more compounds of formula I, preferably compounds of formula I-1 and LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of formula Z1, Z2 and Z3 or their subformulae, one or more compounds selected from the group consisting of formula XIV, one or more compounds selected from the group consisting of formula IV, VI, XX, XXIII and XXIX or their subformulae, and one or more compounds selected from the group consisting of formula LP2-1, XVI, XVIIa, XVIIb, XVIIc, XXXI and S or their subformulae. - The LC medium comprises one or more compounds of formula I, preferably compounds of formula I-1, LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of formula Z1, Z2, Z3, Z4 and Z5 or their subformulae, one or more compounds selected from the group consisting of formula XIVd or their subformulae, one or more compounds selected from the group consisting of formula IVc, VIb, XXa, XXIIIa and XXIXa or their subformulae and one or more compounds selected from the group consisting of formula LP1-1b, XVIb, XVIc, XVIIa, XVIIb, XVIIc, XXXI and S or their subformulae. - The LC medium comprises one or more compounds of formula I, preferably compounds of formula I-1, LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of formula Z1, Z2 and Z3 or their subformulae, one or more compounds of formula Y, preferably selected from the group consisting of formula Y1 and Y2, one or more compounds selected from the group consisting of formula XIV, one or more compounds selected from the group consisting of formula II, III, IV, VI, XX, XXIII and XXIX or their subformulae and one or more compounds selected from the group consisting of formula LP2-1, XVI, XVIIa, XVIIb, XVIIc, XXXI and S or their subformulae. - The LC medium comprises one or more compounds of formula I, preferably compounds of formula I-1, LP1 and/or LP2, one or more compounds selected from the group consisting of formula Z1, Z2, Z3, Z4 and Z5 or their subformulae, one or more compounds of formula B, preferably selected from the group consisting of formula B1, B2 and B3, one or more compounds of formula XIVd or their subformulae, one or more compounds selected from the group consisting of formula II, III, IVc, VIb, XXa, XXIIIa and XXIXa or their subformulae and one or more compounds selected from the group consisting of formula LP1-1b, XVIb, XVIc, XVIIa, XVIIb, XVIIc, XXXI and S or their subformulae. -    In addition to the compounds of formula I, LP1 and/or LP2, the LC medium also comprises other compounds selected from the group of compounds of formula Z1, Z2, Z3, IV, LP1-1, XIV, XVI, XVIIa, XVIIb, XVIIc, XXI, XXIII, XXIX, XXX, XXXI and XXIV or their subformulae. -    In addition to the compounds of formula I, LP1 and/or LP2, the LC medium also comprises other compounds selected from the group of compounds of formula Z1, Z2, Z3, IV, LP2-1, XIV, XVI, XVIIa, XVIIb, XVIIc, XXI, XXIII, XXIX, XXX, XXXI and XXIV or their subformulae. -    The proportion of the compound of formula I or its subformulae in the LC medium is 1 to 30% by weight, preferably 2 to 25% by weight, and most preferably 2 to 20% by weight. -    The proportion of compounds of the formulae Z1, Z2, Z3, Z4 and Z5 or their subformulae in the LC medium is in the total range of 10 to 65 wt. %, preferably 20 to 60 wt. -    The proportion of compounds of the formulae Y or their subformulae in the LC medium is in the total range of 0 to 15 wt. %, preferably 2 to 10 wt. -    The proportion of compounds of the formulae B or their subformulae in the LC medium is in the total range of 0 to 15 wt. %, preferably 2 to 10 wt. -    The proportion of compounds of the formulae II, III, IV to VIII, XVIII to XXIII and XXVII to XXX in the LC medium is in the total range of 30 to 60 wt. -    The proportion of compounds of the formulae XIV and XV in the LC medium is in the total range of 40 to 70 wt. -    The proportion of compounds of the formulae XIV, XVIIa to c and XXXI to XXXIII in the LC medium is in the total range of 0.5 to 15 wt.

The term "alkyl" or "alkyl*" in this application includes straight-chain and branched alkyl groups having 1 to 6 carbon atoms, in particular the straight-chain groups methyl, ethyl, propyl, butyl, pentyl and hexyl. Groups having 2 to 5 carbon atoms are generally preferred.

The term "alkenyl" or "alkenyl*" comprises straight-chain and branched alkenyl groups having 2 to 6 carbon atoms, in particular straight-chain groups. Preferred alkenyl groups are _C2 - _C7-1E -alkenyl, _C4 - _C6-3E -alkenyl, in particular _C2 - _C6-1E -alkenyl. Particularly preferred examples of alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 3-butenyl, 3E-pentenyl, 3E-hexenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl and 5-hexenyl. Groups having up to 5 carbon atoms are generally preferred, in particular _CH2 =CH, _CH3CH =CH.

The term "fluoroalkyl" preferably includes linear groups with terminal fluorine, i.e. fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. However, fluorine at other positions is not excluded.

The term "oxyheteroalkyl" or "alkoxy" preferably includes a linear group of the formula _{CnH2n +1} -O-( _CH2 ) _m , wherein n and m each independently represent 1 to 6. m may also represent 0. Preferably, n = 1 and m = 1 to 6 or m = 0 and n = 1 to 3. In addition, preferably, the alkoxy or oxyheteroalkyl group may also contain one or more additional O atoms so that the oxygen atoms are not directly connected to each other.

By suitable choice of the meaning of ^R0 and ^X0 in formulae II and III, the addressing time, the threshold voltage, the steepness of the transfer characteristic line, etc. can be modified in the desired manner. For example, compared to alkyl and alkoxy groups, 1E-alkenyl, 3E-alkenyl, 2E-alkenyloxy and the like generally lead to shorter addressing times, improved nematicity and a higher ratio between the elastic constants _K3 (bend) and _K1 (bend). Compared to alkyl and alkoxy groups, 4-alkenyl, 3-alkenyl and the like generally lead to lower threshold voltages and lower _K3 / _K1 values. The LC media according to the invention are distinguished in particular by high Δε values and therefore have significantly faster reaction times than LC media from the prior art.

The optimum mixing ratio of the compounds of the above-mentioned formulae depends largely on the desired properties, the choice of the component of the above-mentioned formulae and the choice of any other components that may be present.

A suitable mixing ratio within the range indicated above can be easily determined according to the specific circumstances.

The total amount of compounds of the above-mentioned formulae in the LC medium according to the invention is not critical. The LC media may therefore comprise one or more further components for the purpose of optimizing various properties. However, the higher the total concentration of compounds of the above-mentioned formulae, the greater the effect on the desired improvement of the properties of the medium is generally observed. In a particularly preferred embodiment, the LC medium according to the invention comprises compounds of the formulae IV to VIII (preferably IV and V), wherein ^X0 represents F, _OCF3 , _OCHF2 , OCH= _CF2 , OCF= _CF2 or _OCF2 - _CF2H . The advantageous synergistic effect of using compounds of the formulae I, LP1 and/or LP2, II and III leads in particular to advantageous properties. In particular, LC media comprising compounds of the formula I, LP1 and/or LP2, II and III are distinguished by their equally low threshold voltages.

The individual compounds of the formulae mentioned above and their subformulae which can be used in the LC media according to the invention are known or can be prepared analogously to known compounds.

The present invention also relates to a method for preparing an LC medium as described above and below, by mixing one or more compounds of formula I with one or more compounds of formula LP1 and/or LP2, and one or more compounds selected from the group consisting of formula II, III, Z1, Z2, Z3, Z4, IV, VI, XIV, LP2-1, XVI, XVIIa, XVIIb, XVIIc, XX, XXIII, XXIX, XXXI and S.

The LC medium of the invention may optionally comprise one or more polymerizable compounds. The polymerizable compounds are preferably selected from the formula M R ^a -B ¹ -(Z ^b -B ² ) _m -R ^b M in which the individual substituents have the following meanings on each occurrence, identically or differently and independently of one another: R ^a and R ^b are P, P-Sp-, H, F, Cl, Br, I, -CN, -NO ₂ , -NCO, -NCS, -OCN, -SCN, SF ₅ or linear or branched alkyl having 1 to 25 C atoms, wherein, in addition, one or more non-adjacent CH ₂ groups may each independently of one another be substituted by -C(R ⁰ )=C(R ⁰⁰ )-, -C≡C-, -N(R 00 )-, -C≡C-, -C(R ⁰⁰ )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- are replaced in such a way that the O and/or S atoms are not directly connected to each other, and wherein, in addition, one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, wherein if ^B1 and/or ^B2 contain a saturated C atom, then ^Ra and/or ^Rb may also represent a group spiro-connected to the saturated C atom, wherein at least one of the substituents Ra and Rb represents or contains a group P or P-Sp-, P is a polymerizable group, Sp is a spacer group or a single bond, ^B1 and B2 contain a saturated C atom, and Ra and ^/ or ^Rb contain a saturated C atom. ² an aromatic, heteroaromatic, alicyclic or heterocyclic group, preferably having 4 to 25 ring atoms, which may also contain a fused ring, and which is unsubstituted or mono- or poly-substituted by L, Z ^b -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH ₂ -, -CH ₂ O-, -SCH ₂ -, -CH ₂ S-, -CF 2 O-, -OCF ₂ -, -CF ₂ S-, -SCF ₂ -, -(CH ₂ ) _n1 -, -CF ₂ CH ₂ -, _{-CH 2 CF 2} -, -(CF ₂ ) _n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, CR ⁰ R ⁰⁰ or a single bond, R ⁰ and R ⁰⁰ each independently represent H or an alkyl group having 1 to 12 C atoms, m represents 0, 1, 2, 3 or 4, n1 represents 1, 2, 3 or 4, L P, P-Sp-, OH, CH ₂ OH, F, Cl, Br, I, -CN, -NO ₂ , -NCO, -NCS, -OCN, -SCN, -C(=O)N(R ^x ) ₂ , -C(=O)Y ¹ , -C(=O)R ^x , -N(R ^x ) ₂ , optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or a linear or branched alkyl group, alkoxy group, alkylcarbonyl group, alkoxycarbonyl group, alkylcarbonyloxy group or alkoxycarbonyloxy group having 1 to 25 C atoms, wherein, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, P and Sp has the meaning indicated in the above formula M, ^Y represents a halogen, ^R represents P, P-Sp-, H, a halogen, a linear, branched or cyclic alkyl group having 1 to 25 C atoms, wherein, in addition, one or more non-adjacent _CH groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and/or S atoms are not directly connected to one another, and wherein, in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

Particularly preferred compounds of the formula M are those wherein B ¹ and B ² are independently 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 9,10-dihydro-phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, flavonoids, wherein in addition, one or more CH groups of these groups may be replaced by N, cyclohexane-1,4-diyl, wherein in addition, one or more non-adjacent CH ₂ group may be replaced by O and/or S, 1,4-cyclohexenyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indane-2,5-diyl or octahydro-4,7-methanoindane-2,5-diyl, wherein all of these groups may be unsubstituted or mono- or poly-substituted by L as defined for formula M above.

Particularly preferred compounds of the formula M are those in which B ¹ and B ² each independently represent 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

Most preferred compounds of formula M are selected from the following formulas: wherein the individual substituents have the following meanings on each occurrence, identically or differently and independently of one another: ^P1 , ^P2 , ^P3 polymerizable groups, preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, cyclohexane and epoxy resins, ^Sp1 , ^Sp2 , ^Sp3 single bond or spacer groups, wherein, in addition, one or more of the substituents ^P1 - ^Sp1- , ^P1 - ^Sp2- and ^P3 - ^Sp3- may represent ^Raa , with the proviso that at least one of the substituents ^P1 - ^Sp1- , ^{P2- Sp2} and ^P3 - ^Sp3- present is different from ^Raa , preferably -( _CH2 ) _p1- , -( _CH2 ) _p1 -O-, -( _CH2 ) _p1 -CO-O- or -(CH ₂ ) _p1 -O-CO-O-, wherein p1 is an integer from 1 to 12, R ^aa H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, wherein, in addition, one or more non-adjacent CH ₂ groups can each independently of one another be replaced by -C(R ⁰ )=C(R ⁰⁰ )-, -C≡C-, -N(R ⁰ )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and/or S atoms are not directly connected to one another, and wherein, in addition, one or more H atoms can be replaced by F, Cl, CN or P ¹ -Sp ¹ -substituted by a straight or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms, wherein the alkenyl and alkynyl radicals have at least two C atoms and the branched radicals have at least three C atoms, ^R0 , ^R00H or alkyl having 1 to 12 C atoms, ^Ry and ^RzH , F, _CH3 or _CF3 , ^X1 , ^X2 , ^X3 -CO-O-, -O-CO- or a single _bond , ^ZM1 -O-, -CO-, -C( ^{RyRz )} - or _-CF2CF2- , ^ZM2 , ^ZM3 -CO-O-, -O _- CO-, _-CH2O- , -OCH2-, _{-CF2O-, -OCF2- or} -(CH ₂ ) _n- , wherein n is 2, 3 or 4, LF, Cl, CN or a linear or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms, L ^' , L ^'' H, F or Cl, r 0, 1, 2, 3 or 4, s 0, 1, 2 or 3, t 0, 1 or 2, x 0 or 1.

Particularly preferred are compounds of formula M2 and M13.

Other preferred are tri-reactive compounds M15 to M31, especially M17, M18, M19, M22, M23, M24, M25, M30 and M31. In the compounds of formula M1 to M31, the group Prefer , , , , or , in which L has, on each occurrence, identically or differently, one of the meanings given for formula M above and below, and is preferably F, Cl, CN, NO ₂ , CH ₃ , C ₂ H ₅ , C(CH ₃ ) ₃ , CH(CH ₃ ) ₂ , CH ₂ CH(CH ₃ )C ₂ H ₅ , OCH ₃ , OC ₂ H ₅ , COCH ₃ , COC ₂ H ₅ , COOCH ₃ , COOC ₂ H ₅ , CF ₃ , OCF ₃ , OCHF ₂ , OC ₂ F ₅ or P-Sp-, very preferably F, Cl, CN, CH ₃ , C ₂ H ₅ , OCH ₃ , COCH ₃ , OCF ₃ or P-Sp-, more preferably F, Cl, CH ₃ , OCH ₃ , COCH ₃ or OCF ₃ , especially F or CH ₃ .

Preferred compounds of formulae M1 to M31 are those wherein ^P1 , ^P2 and ^P3 represent acrylate, methacrylate, cyclohexane or epoxy groups, most preferably acrylate or methacrylate groups.

Preferred compounds of formulae M1 to M31 are those wherein Sp ¹ , Sp ² and Sp ³ are single bonds.

Other preferred compounds of formulae M1 to M31 are those wherein one of Sp ¹ , Sp ² and Sp ³ is a single bond and another one of Sp ¹ , Sp ² and Sp ³ is different from a single bond.

Other preferred compounds of formulae M1 to M31 are those wherein the groups ^Sp1 , ^Sp2 and ^Sp3 which are different from single bonds represent -( _CH2 ) _s1 -X ^" -, wherein s1 is an integer from 1 to 6, preferably 2, 3, 4 or 5, and X ^" is a bond to the benzene ring and is -O-, -O-CO-, -CO-O-, -O-CO-O- or a single bond.

Particularly preferred are LC media comprising one, two or three polymerizable compounds of the formula M, preferably selected from polymerizable compounds of the formulae M1 to M31.

Further preferably, the LC medium according to the present invention comprises one or more polymerizable compounds selected from Table H below.

Preferably, the proportion of polymerizable compounds, preferably selected from the group consisting of formula M and table H, in the LC medium is from 0.01 to 5%, very preferably from 0.05 to 1%, most preferably from 0.1 to 0.5%.

It was observed that the addition of one or more polymerizable compounds to the LC medium, such as those selected from Formula M and Table H, results in advantageous properties such as fast reaction time. This LC medium is particularly suitable for use in PSA displays, where it exhibits low image retention, fast and complete polymerization, fast generation of stable low pretilt angles after UV exposure, high reliability, high VHR values after UV exposure and high birefringence. By appropriate selection of the polymerizable compounds, it is possible to increase the absorption of the LC medium at longer UV wavelengths, making it possible to use these longer UV wavelengths for polymerization, which is advantageous for display manufacturing methods.

The polymerizable group P is a group suitable for polymerization reactions (such as free radical or ionic chain polymerization, complex addition or polymerization) or for polymer-analogous reactions (such as addition or condensation to the main polymer chain). Particularly preferred are groups for chain polymerization, especially those containing a C=C double shoulder or a -C≡C- triple bond, and groups suitable for polymerization by ring opening, such as, for example, cyclohexane or epoxide groups.

A preferred group P is selected from the group consisting of: CH ₂ =CW ¹ -CO-O-, CH ₂ =CW ¹ -CO-, , , , , CH ₂ =CW ² -(O) _k3 -, CW ¹ =CH-CO-(O) _k3 -, CW ¹ =CH-CO-NH-, CH ₂ =CW ¹ -CO-NH-, CH ₃ -CH=CH-O-, (CH ₂ =CH) ₂ CH-OCO-, (CH ₂ =CH-CH ₂ ) ₂ CH-OCO-, (CH ₂ =CH) ₂ CH-O-, (CH ₂ =CH-CH ₂ ) ₂ N-, (CH ₂ =CH-CH ₂ ) ₂ N-CO-, HO-CW ² W ³ -, HS-CW ² W ³ -, HW ² N-, HO-CW ² W ³ -NH-, CH ₂ =CW ¹ -CO-NH-, CH ₂ =CH-(COO) _k1 -Phe-(O) _k2 -, CH ₂ =CH-(CO) _k1 -Phe-(O) _k2 -, Phe-CH=CH-, HOOC-, OCN- and ^W4W5W6Si- , wherein ^W1 represents H, F, Cl, CN, _CF3 , phenyl or alkyl having 1 to ⁵ C atoms, in particular H, F, _Cl or CH3, ^W2 and ^W3 each independently represent H or alkyl having 1 to 5 C atoms, in particular H, methyl, ^ethyl or n-propyl, ^W4 , W5 and W6 each independently represent Cl, oxoalkyl or oxocarbonylalkyl having 1 to 5 C atoms, W7 and ^W8 each independently represent H, Cl or alkyl having 1 to 5 C atoms, Phe represents 1,4-phenylene which is optionally substituted by one or more substituents L as defined for the above formula M except P-Sp-, k1, ^k2 and k6 are each independently selected from the group consisting of: -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W4W5W6Si-, wherein W1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, ^W2 and ^W3 each independently represent H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W4, W5 and W6 each independently represent Cl, oxoalkyl or oxocarbonylalkyl having 1 to 5 C atoms, _W7 and W8 each independently represent H, Cl or alkyl having ₁ to 5 C atoms, _k3 each independently represents 0 or 1, _k3 preferably represents 1, and _k4 represents an integer from 1 to 10.

The most preferred group P is selected from the group consisting of: CH ₂ =CW ¹ -CO-O-, CH ₂ =CW ¹ -CO-, , , , , CH ₂ =CW ² -O-, CH=CW ² -, CW ¹ =CH-CO-(O) _k3 -, CW ¹ =CH-CO-NH-, CH ₂ =CW ¹ -CO-NH-, (CH ₂ =CH) ₂ CH-OCO-, (CH ₂ =CH-CH ₂ ) ₂ CH-OCO-, (CH ₂ =CH) ₂ CH-O-, (CH ₂ =CH-CH ₂ ) ₂ N-, (CH ₂ =CH-CH ₂ ) ₂ N-CO-, CH ₂ =CW ¹ -CO-NH-, CH ₂ =CH-(COO) _k1 -Phe-(O) _k2 -, CH ₂ =CH-(CO) _k1 -Phe-(O) _k2 -, Phe-CH=CH- and W ⁴ W ⁵ W ⁶ Si-, where W ¹ represents H, F, Cl, CN, CF ₃ W ₄ , W ^{5 and W 6 each independently represent Cl, an oxoalkyl group or an oxocarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently represent H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k 1 , k 2 and k 3} _each ^{independently represent} 0 or 1 _{, k 3 preferably represents 1, and k 4} ^represents _{an integer} from 1 to ₁₀ .

Particularly preferred groups P are selected from the group consisting of CH ₂ =CW ¹ -CO-O-, in particular CH ₂ =CH-CO-O-, CH ₂ =C(CH ₃ )-CO-O- and CH ₂ =CF-CO-O-, furthermore CH ₂ =CH-O-, (CH ₂ =CH) ₂ CH-O-CO-, (CH ₂ =CH) ₂ CH-O-, and .

Other preferred polymerizable groups P are selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, cyclohexane and epoxide, and are most preferably selected from acrylate and methacrylate.

If Sp is different from a single bond, it preferably has the formula Sp ^" -X ^" , so that the respective substituent P-Sp- corresponds to the formula P-Sp ^" -X ^" -, wherein Sp ^" is an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein, in addition, one or more non-adjacent _CH2 groups may each be independently substituted by -O-, -S-, -NH-, -N( ^R0 )-, -Si ^{(R0R00 )} -, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N( ^R00 )-CO-O-, -O-CO-N( ^R0 )-, -N( ^R0 )-CO-N( ^R00)- )-, -CH=CH- or -C≡C- is replaced in such a way that the O and/or S atoms are not directly connected to each other, X ^" represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R ⁰ )-, -N(R ⁰ )-CO-, -N(R ⁰ )-CO-N(R ⁰⁰ )-, -OCH ₂ -, -CH ₂ O-, -SCH ₂ -, -CH ₂ S-, -CF _{2 O-} , -OCF ₂ -, -CF ₂ S-, -SCF 2 -, -CF ₂ CH ₂ -, _{-CH 2} CF 2 -, -CF ₂ CF ₂ -, -CH=N-, -N=CH-, -N=N-, -CH=CR ⁰ -, -CY ² =CY ³ -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond, ^R0 and ^R00 each independently represent H or an alkyl group having 1 to 20 C atoms, and ^Y2 and ^Y3 each independently represent H, F, Cl or CN.

X ^" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR ⁰ -, -NR ⁰ -CO-, -NR ⁰ -CO-NR ⁰⁰ - or a single bond.

Typical spacer groups Sp and -Sp ^" -X ^" - _are , for example, -( _CH2 ) _p1- , -( _CH2CH2O ) _{q1 - CH2CH2-} , _{-CH2CH2 -} S _{-CH2CH2- ,} -CH2CH2- _{NH - CH2CH2-} , or -( ^{SiR0R00 -} O) _p1- , wherein p1 is an integer from 1 to ₁₂ , q1 is an integer from 1 to 3, and ^R0 and ^R00 have the meanings indicated in the above formula M.

Particularly preferred groups Sp and -Sp ^" -X ^" - are -( _CH2 ) _p1- , -( _CH2 ) _p1 -O-, -( _CH2 ) _p1 -O-CO-, -( _CH2 ) _p1 -CO-O-, -( _CH2 ) _p1 -O-CO-O-, wherein p1 and q1 have the meanings indicated above.

Particularly preferred radicals Sp ^" are in each case linear ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, octadecyl, ethyloxyethyl, methyleneoxybutyl, ethylthioethyl, ethyl-N-methyliminoethyl, 1-methylalkyl, vinyl, propenyl and butenyl.

For the production of PSA displays, the polymerizable compounds contained in the LC medium are polymerized or crosslinked (if a compound contains two or more polymerizable groups) by in situ polymerization in the LC medium between the substrates of the LC display, optionally while applying a voltage to the electrodes.

The structure of the PSA display according to the invention corresponds to the general geometry of PSA displays, as described in the prior art cited at the outset. Geometries without protrusions are preferred, in particular those in which the electrode on the color filter side is not structured and only the electrode on the TFT side has slits. A particularly suitable and preferred electrode structure for PS-VA displays is described, for example, in US 2006/0066793 A1.

The combination of the compounds of the preferred embodiments mentioned above with the polymeric compounds described above leads to low critical voltages, low rotational viscosities and very good low temperature stability in the LC media according to the invention with constantly high clearing points and high VHR values.

The use of LC media containing polymerizable compounds allows particularly low pretilt angles to be rapidly established in PSA displays. In particular, these LC media show significantly shorter response times in PSA displays, in particular also grayscale response times, compared to media from the prior art.

Generally, LC media having a nematic LC phase and preferably a chiral LC phase are preferred.

The invention also relates to the use of an LC medium according to the invention as described above and below for electro-optical purposes, in particular in shutter glasses, for 3D applications, in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA and positive PS-VA displays, and to an electro-optical display containing an LC medium according to the invention as described above and below, in particular an electro-optical display of the aforementioned type, in particular a TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA (vertically aligned) or positive PS-VA display.

The invention also relates to an electro-optical display, such as for example a STN or matrix LC (MLC) display, having two plane-parallel outer plates (these outer plates together with the frame form a cell), an integrated nonlinear element for switching individual pixels on the outer plates, and a nematic LC medium with positive dielectric anisotropy and high specific resistance located in the cell, wherein the nematic LC medium is an LC medium according to the invention as described above and below.

The LC medium according to the invention is able to significantly broaden the available parameter latitude. The achievable combination of clearing point, viscosity at low temperatures, thermal and UV stability and high optical anisotropy is far superior to previous materials from the prior art.

In particular, the combination of compounds of formula I with compounds of formula LP1 and/or LP2, and optionally with compounds selected from formulae II to XXXIII or their subformulae, leads to LC media showing moderately positive dielectric anisotropy and simultaneously increasing the dielectric constant ε _┴ perpendicular to the longitudinal axis of the LC molecules, while maintaining low rotational viscosity and low values of the ratio γ ₁ /K _1. This enables energy-saving LC displays, in particular LC displays in FFS, HB-FFS, XB-FFS and IPS mode, with high brightness and high transmission and low response time.

The LC medium according to the invention is suitable for mobile applications and TFT applications, such as, for example, mobile phones and PDAs. In addition, the LC medium according to the invention is particularly suitable for FFS, HB-FFS, XB-FFS and IPS displays based on positive dielectric liquid crystals.

The LC medium according to the invention allows to achieve a rotational viscosity γ1 ≤ 120 mPa·s, particularly preferably ≤ 100 mPa·s, while maintaining a nematic phase down to -20°C and preferably down to -30°C, particularly preferably down to -40°C, and a clearing point ≥ 75°C, particularly preferably ≥ 80°C, so that an excellent MLC display with a fast response time can be achieved. The rotational viscosities are measured at 20°C.

The dielectric anisotropy Δε of the LC medium according to the invention at 20°C and 1 kHz is preferably ≥ +1.5, very preferably +3 to +18, and most preferably +5 to +15.

The birefringence Δn of the LC medium according to the invention at 20°C is preferably from 0.08 to 0.2, most preferably from 0.09 to 0.15.

The rotational viscosity γ1 of the LC medium according to the present invention is preferably ≤ 120 mPa·s, more preferably ≤ 110 mPa·s, and most preferably ≤ 90 mPa·s.

The ratio γ ₁ /K ₁ (wherein γ ₁ is the rotational viscosity and K ₁ is the elastic constant of the flexural deformation) of the LC medium according to the invention is preferably ≤ 7 mPa ^. s/pN, very preferably ≤ 6 mPa ^. s/pN, and most preferably ≤ 5.5 mPa ^. s/pN.

The average elastic constant ratio _Kav of the LC medium according to the present invention is preferably at least 14.0 pN, very preferably at least 15.0 pN, and most preferably at least 16.0 pN. _Kav can be calculated according to the following formula: _Kav = ( _K1 + _K2 + _K3 ) / 3 ≈ ( _K1 + ½ * _K1 + _K3 ) / 3.

The nematic phase range of the LC medium according to the invention preferably has a width of at least 90° C., more preferably at least 100° C., in particular at least 110° C. This range preferably extends from at least -25° C. to +90° C.

It goes without saying that by suitable choice of the components of the LC medium according to the invention it is also possible to achieve higher clearing points (e.g. above 100° C.) at higher threshold voltages or lower clearing points at lower threshold voltages while retaining other advantageous properties. It is likewise possible to obtain LC media with higher Δε and therefore lower threshold values, with a correspondingly only slightly increased viscosity. The MLC display according to the invention is preferably operated in the first Gooch and Tarry transmission minimum [C.H. Gooch and H.A. Tarry, Electron. Lett. 10, 2-4, 1974; C.H. Gooch and H.A. Tarry, Appl. Phys., Vol. 8, 1575-1584, 1975], wherein, in addition to particularly advantageous electro-optical properties such as, for example, a high steepness of the characteristic lines and a low angular dependence of the contrast (German Patent 30 22 818), a lower dielectric anisotropy is sufficient in the second minimum at the same critical voltage as in similar displays. This enables significantly higher specific resistance values to be achieved with the LC medium according to the invention at the first minimum than in the case of LC media comprising cyano compounds. By suitable choice of the individual components and their proportions by weight, a person skilled in the art can set the necessary birefringence for a predefined layer thickness of the MLC display using simple routine methods.

The measured values of voltage holding ratio (HR) [S. Matsumoto et al., Liquid Crystals 5, 1320 (1989); K. Niwa et al., Proc. SID Conference, San Francisco, June 1984, p. 304 (1984); G. Weber et al., Liquid Crystals 5, 1381 (1989)] have shown that the LC medium according to the present invention comprising compounds of the formulae ST-1, ST-2, RV, IA and IB exhibits higher voltage holding ratios when exposed to UV than the LC medium comprising the formulae Cyanophenylcyclohexane or The HR reduction of the esters was significantly smaller in similar LC media.

The photostability and UV stability of the LC media according to the invention are considerably better, ie they show a significantly smaller HR drop when exposed to light, heat or UV.

The MLC display constructed of polarizer, electrode substrate and surface treated electrode according to the present invention corresponds to the general design of this type of display. The term general design is used here in a general sense and also includes all derivatives and modifications of the MLC display, in particular including matrix display elements based on poly-Si TFT or MIM.

However, a significant difference between the display according to the invention and the hitherto known displays based on twisted nematic cells lies in the choice of the LC parameters of the LC layer.

The LC media which can be used according to the invention are prepared in a manner known per se, for example by mixing one or more compounds of variant 1 with one or more compounds of the formulae II-XXXIIII or with other LC compounds and/or additives. In general, the required amount of the component used in smaller amounts is dissolved in the component constituting the main constituents, advantageously at elevated temperature. It is also possible to mix the solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again after thorough mixing, for example by distillation.

The LC medium may also contain other additives known to those skilled in the art and described in the literature, such as, for example, polymerization initiators, inhibitors, surfactants, light stabilizers, antioxidants (e.g., BHT, TEMPOL), microparticles, free radical scavengers, nanoparticles, etc. For example, 0 to 15% of a polychromatic dye or a chiral dopant or an initiator such as Irgacure® 651 or Irgacure® 907 may be added. Suitable stabilizers and dopants are mentioned in Tables F and G below. In a preferred embodiment, the LC medium contains one or more stabilizers selected from Table G. Preferably, the proportion of stabilizers (such as those having the formula ST and H, as described above or listed in Table G) in the LC medium is 10 to 2000 ppm, most preferably 30 to 1000 ppm.

Furthermore, it is possible to add, for example, 0 to 15% by weight of pleochroic dyes, also nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258 (1973)) to the LC medium for improving the conductivity, or substances for improving the dielectric anisotropy, viscosity and/or alignment of the nematic phase. Substances of this type are described, for example, in DE-A 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.

For the present invention and in the following examples, the structures of the LC compounds are indicated by means of acronyms and the conversion of the chemical formulae is carried out according to the following Tables A to C. All substituents _{CmH2m +1} , _{CnH2n +1} and _C1H2l +1 or _{CmH2m -1} , _{CnH2n -1} and _C1H2l-1 are linear alkyl or alkylene radicals, in each case with n, m and 1 C atoms, respectively. Preferably, n, m and 1 are independently 1, 2 _, 3, 4, 5, 6 or 7. Table A shows the code of the ring elements of the compound core, _Table B lists the bridging units and Table C lists the meaning of the symbols of the left-hand and right-hand terminal groups of the molecule. The acronyms consist of the code of the ring element with an optional linking group, followed by the first hyphen and the code of the left terminal group, and the second hyphen and the code of the right terminal group. Table D shows illustrative structures of compounds together with their respective acronyms. Table A : Ring Elements Table B : Bridge Unit Table C : End Groups Where n and m are integers, and the three dots "..." are placeholders for other abbreviations from this table.

The following abbreviations are used: (n, m, k and l are each independently an integer, preferably 1 to 12, preferably 1 to 6, and k and l may also be 0 and preferably 0 to 4, more preferably 0 or 2 and most preferably 2, n is preferably 1, 2, 3, 4 or 5, in the combination "-nO-", it is preferably 1, 2, 3 or 4, preferably 2 or 4, m is preferably 1, 2, 3, 4 or 5, in the combination "-Om", it is preferably 1, 2, 3 or 4, more preferably 2 or 4. The combination "-lVm" is preferably "2V1").

Preferred compositions of LC media are shown in Tables D and E. Table D Table E In the following formula, n and m each independently represent 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, in particular 2, 3, 5, and furthermore 0, 4, 6.

It is particularly preferred that the LC medium comprises, in addition to the compounds of the formula I, LP1 and/or LP2, at least one, two, three, four or more compounds from Table E.

Table F Table F indicates possible dopants which are typically added to the LC media according to the invention. The LC media preferably comprise 0 to 10% by weight, in particular 0.01 to 5% by weight and particularly preferably 0.01 to 3% by weight of dopants.

Table G below mentions stabilizers which can additionally be added, for example, to the LC medium according to the invention in an amount of 0 to 10% by weight. n = 1, 2, 3, 4, 5, 6, or 7 n = 1, 2, 3, 4, 5, 6, or 7 n = 1, 2, 3, 4, 5, 6, or 7 q = 1, 2, 3, 4, 5, 6, or 7 q = 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10

Table H Table H shows illustrative reactive mesogen compounds (RM) that can be used in the LC media according to the present invention.

In a preferred embodiment, the mixture according to the present invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formula RM-1 to RM-182. Among them, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-58, RM-64, RM-74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-1 09. RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-1 45. RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-183 are particularly good.

Table 1 Table 1 shows self-aligning additives for vertical alignment that can be used in the LC medium of SA-FFS, SA-HB-FFS and SA-XB-FFS displays according to the present invention:

In a preferred embodiment, the LC medium, SA-VA and SA-FFS display according to the present invention comprises one or more SA additives selected from formulas SA-1 to SA-48, preferably selected from formulas SA-14 to SA-48, and most preferably selected from formulas SA-20 to SA-34 and SA-44, in combination with one or more RMs.

The following examples are intended to illustrate the present invention rather than to limit it.

Above and below, percentage data refer to percentages by weight. All temperatures are indicated in degrees Celsius. mp = melting point, cl.p. = clearing point. In addition, C = crystalline, N = nematic, S = smectic and I = isotropic. The data between these symbols refer to the transition temperatures. In addition, the following symbols are used: _V0 the capacitive Freedericks threshold voltage at 20°C [V], V10 the voltage for ₁₀ % transmission [V], _ne the anomalous refractive index measured at 20°C and 589 nm, _n0 the ordinary refractive index measured at 20°C and 589 nm, Δn the optical anisotropy measured at 20°C and 589 nm, _ε┴ the dielectric susceptibility (or "dielectric constant") perpendicular to the longitudinal axis of the molecule at 20°C and 1 kHz, ε _|| the dielectric susceptibility (or "dielectric constant") parallel to the longitudinal axis of the molecule at 20°C and 1 kHz, Δε the dielectric anisotropy at 20°C and 1 kHz, cl.p. or T(N,I) Clearing point [℃], ν the flow viscosity measured at 20℃ [mm ² ·s ^-1 ], γ ₁ the rotational viscosity measured at 20℃ [mPa·s], K ₁ the elastic constant, the "bending" deformation at 20℃ [pN], K ₂ the elastic constant, the "twisting" deformation at 20 ℃ [pN], K ₃ the elastic constant, the "bending" deformation at 20℃ [pN], and VHR the voltage holding ratio.

All physical properties were determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", status Nov. 1997, Merck KGaA, Germany and apply at a temperature of 20°C unless expressly indicated otherwise.

Examples Example M1 ( comparison ) Nematic LC medium is prepared as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 77.1 ℃ 2 CC-3-V 37.0 Δn (20℃, 589 nm) = 0.1335 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6274 4 CCP-V-1 5.5 n _o (589 nm, 20℃) = 1.4939 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.2 6 PGP-1-2V 5.25 ε _‖ (20℃, 1kHz) = 5.8 7 PGUQU-3-F 4.0 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-4-F 3.0 γ1 (20℃) = 56 mPa·s 9 PGUQU-5-F 1.75 _K1 (20℃) = 17.0 pN 10 PP-1-2V1 10.0 _K3 (20℃) = 15.1 pN 11 PUS-3-2 15.5 V ₀ (20℃) = 2.43 V The LC mixture had a _Kav of 13.50 pN and a γ ₁ /K ₁ of 3.29 mPa s/pN.

Mixture Example S1 ( Stabilized by Compound of Formula ST-1-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M1 99.95% by weight Compound of formula ST-1-3 500 ppm The addition of 500 ppm of the compound of formula ST-1-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M1 without affecting the remaining physical properties of the mixture M1. ST-1-3

Example M2 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 81.3 ℃ 2 CC-3-V 36.5 Δn (20℃, 589 nm) = 0.1343 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6272 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4929 5 CCP-V-1 2.25 Δε (20℃, 1kHz) = 3.4 6 CLP-3-T 7.0 ε _‖ (20℃, 1kHz) = 6.0 7 PGP-1-2V 8.0 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 59 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 18.0 pN 10 PGUQU-5-F 2.25 _K3 (20℃) = 15.7 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.44 V 12 PUS-3-2 13.0 The LC mixture has a _Kav of 14.23 pN and a _γ1 / _K1 of 3.28 mPa s/pN. Thus, the LC mixture of Example 2 (inventive) has a significantly higher average elastic constant _Kav than the LC mixture of Example 1 (comparative), while the reaction time parameter _γ1 / _K1 of the two mixtures is substantially the same.

Mixture Example S2 ( Stabilized by Compound of Formula H-3-1 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M2 99.9% by weight Compound of formula H-3-1 1000 ppm Compared to the unstabilized mixture M2, the addition of 1000 ppm of the compound of formula H-3-1 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M2. H-3-1

Example M3 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 82.8 ℃ 2 CC-3-V 35.75 Δn (20℃, 589 nm) = 0.1346 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6284 4 CCC-3-V 2.0 n _o (589 nm, 20℃) = 1.4938 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.6 6 CLP-V-1 5.5 ε _‖ (20℃, 1kHz) = 6.2 7 PGP-1-2V 6.75 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 60 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 18.8 pN 10 PGUQU-5-F 3.0 _K3 (20℃) = 16.4 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.41 V 12 PUS-3-2 12.0 The LC mixture had a _Kav of 14.87 pN and a γ ₁ /K ₁ of 3.19 mPa s/pN.

Mixture Example S3 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M3 99.95% by weight Compound of formula ST-2-3 500 ppm The addition of 500 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M3 without affecting the remaining physical properties of the mixture M3. ST-2-3

Example M4 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 83 ℃ 2 CC-3-V 35.5 Δn (20℃, 589 nm) = 0.1353 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6282 4 CCC-3-V 5.0 n _o (589 nm, 20℃) = 1.4929 5 CCP-V-1 1.0 Δε (20℃, 1kHz) = 3.5 6 CLP-3-T 7.0 ε _‖ (20℃, 1kHz) = 6.1 7 PGP-1-2V 6.0 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 59 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 19.1 pN 10 PGUQU-5-F 2.5 _K3 (20℃) = 15.9 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.47 V 12 PUS-3-2 15.0 The LC mixture had a _Kav of 14.85 pN and a γ ₁ /K ₁ of 3.09 mPa s/pN.

Mixture Example S4 ( Stabilized by Compound of Formula H-3-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M4 99.9% by weight Compound of formula H-3-3 1000 ppm Compared to the unstabilized mixture M4, the addition of 1000 ppm of the compound of formula H-3-3 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M4. H-3-3

Example M5 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 82.7 ℃ 2 CC-3-V 36.25 Δn (20℃, 589 nm) = 0.1347 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6286 4 CCC-3-V 1.25 n _o (589 nm, 20℃) = 1.4939 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.6 6 CLP-V-1 5.5 ε _‖ (20℃, 1kHz) = 6.2 7 PGP-1-2V 9.25 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 62 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 18.6 pN 10 PGUQU-5-F 3.0 _K3 (20℃) = 16.4 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.40 V 12 PUS-3-2 9.75 The LC mixture had a _Kav of 14.77 pN and a γ ₁ /K ₁ of 3.33 mPa s/pN.

Mixture Example S5 ( Stabilized by Compound of Formula H-3-5 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M5 99.995% by weight Compound of formula H-3-5 50 ppm The addition of 50 ppm of the compound of formula H-3-5 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M5 without affecting the remaining physical properties of the mixture M5. H-3-5

Example M6 ( Inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 1.5 T(N, I) = 83.5 ℃ 2 CC-3-V 37.0 Δn (20℃, 589 nm) = 0.1348 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6291 4 CCC-3-V 1.0 n _o (589 nm, 20℃) = 1.4943 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.6 6 CLP-V-1 7.0 ε _‖ (20℃, 1kHz) = 6.2 7 PGP-1-2V 10.25 ε _┴ (20℃, 1 kHz) = 2.7 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 62 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 18.5 pN 10 PGUQU-5-F 3.0 _K3 (20℃) = 16.5 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.39 V 12 PUS-3-2 8.25 The LC mixture had a _Kav of 14.75 pN and a γ ₁ /K ₁ of 3.35 mPa s/pN.

Mixture Example S6 ( Stabilized by Compound of Formula ST-1-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M6 99.95% by weight Compound of formula ST-1-3 500 ppm The addition of 500 ppm of the compound of formula ST-1-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M6, without affecting the remaining physical properties of the mixture M6.

Example M7 ( Inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 APUQU-3-F 4.0 T(N, I) = 87.9 ℃ 2 CC-3-2V1 4.0 Δn (20℃, 589 nm) = 0.1355 3 CC-3-V 32.0 n _e (589 nm, 20℃) = 1.6286 4 CC-3-V1 8.0 n _o (589 nm, 20℃) = 1.4931 5 CCC-3-V 3.0 Δε (20℃, 1kHz) = 4.0 6 CLP-3-T 7.0 ε _‖ (20℃, 1kHz) = 6.6 7 CLP-V-1 7.0 ε _┴ (20℃, 1 kHz) = 2.6 8 PGP-1-2V 6.5 γ ₁ (20℃) = 66 mPa·s 9 PGUQU-3-F 3.25 _K1 (20℃) = 20.8 pN 10 PGUQU-4-F 4.0 _K3 (20℃) = 17.5 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.42 V 12 PUS-3-2 11.25 The LC mixture had a _Kav of 16.23 pN and a γ ₁ /K ₁ of 3.17 mPa s/pN.

Mixture Example S7 ( Stabilized by Compound of Formula ST-1-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M7 99.97% by weight Compound of formula ST-1-3 300 ppm The addition of 300 ppm of the compound of formula ST-1-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M7 without affecting the remaining physical properties of the mixture M7.

Example M8 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 86.9 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 0.1346 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6278 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4932 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.9 6 CLP-V-1 7.0 ε _‖ (20℃, 1kHz) = 6.5 7 PGP-1-2V 6.5 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 5.0 γ ₁ (20℃) = 64 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 20.0 pN 10 PGUQU-5-F 3.0 _K3 (20℃) = 17.2 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.39 V 12 PUS-3-2 10.25 The LC mixture had a _Kav of 15.73 pN and a γ ₁ /K ₁ of 3.20 mPa s/pN.

Mixture Example S8 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M8 99.96% by weight Compound of formula ST-2-3 400 ppm The addition of 500 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M8, without affecting the remaining physical properties of the mixture M8.

Example M9 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 92.3 ℃ 2 CC-3-V 31.75 Δn (20℃, 589 nm) = 0.1359 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6295 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4936 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 4.4 6 CLP-V-1 7.0 ε _‖ (20℃, 1kHz) = 7.1 7 DLGU-3-F 9.75 ε _┴ (20℃, 1 kHz) = 2.7 8 PGP-1-2V 4.0 γ ₁ (20℃) = 73 mPa·s 9 PGUQU-4-F 2.5 _K1 (20℃) = 23.7 pN 10 PP-1-2V1 10.0 _K3 (20℃) = 20.7 pN 11 PUS-3-2 13.0 V ₀ (20℃) = 2.44 V The LC mixture had a _Kav of 18.75 pN and a γ ₁ /K ₁ of 3.08 mPa s/pN.

Mixture Example S9 ( Stabilized by Compound of Formula H-3-1 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M9 99.9% by weight Compound of formula H-3-1 1000 ppm Compared to the unstabilized mixture M9, the addition of 1000 ppm of the compound of formula H-3-1 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M9.

Example M10 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-V 31.0 T(N, I) = 115.2 ℃ 2 CC-3-V1 8.0 Δn (20℃, 589 nm) = 0.1021 3 CCC-3-V 2.0 n _e (589 nm, 20℃) = 1.5903 4 CCGU-3-F 5.0 n _o (589 nm, 20℃) = 1.4882 5 CCP-V-1 13.5 Δε (20℃, 1kHz) = 4.9 6 CCP-V2-1 5.0 ε _‖ (20℃, 1kHz) = 7.8 7 CCPC-33 1.5 ε _┴ (20℃, 1 kHz) = 2.8 8 CCPC-34 1.5 γ ₁ (20℃) = 103 mPa·s 9 CCVC-3-V 4.0 _K1 (20℃) = 18.5 pN 10 CDUQU-3-F 8.0 _K3 (20℃) = 20.9 pN 11 CLP-V-1 5.0 V ₀ (20℃) = 2.04 V 12 DLGU-3-F 4.0 13 PGP-2-2V 4.0 14 PP-1-2V1 3.5 15 PPGU-3-F 0.5 16 PUQU-3-F 3.5 The LC mixture had a _Kav of 16.22 pN and a γ ₁ /K ₁ of 5.57 mPa s/pN.

Mixture Example S10 ( Stabilized by Compound of Formula H-3-1 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M10 99.9% by weight Compound of formula H-3-1 1000 ppm Compared to the unstabilized mixture M10, the addition of 1000 ppm of the compound of formula H-3-1 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M10.

Example M11 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-V 27.0 T(N, I) = 115.3 ℃ 2 CC-3-V1 8.0 Δn (20℃, 589 nm) = 0.1018 3 CC-4-V1 4.0 n _e (589 nm, 20℃) = 1.5889 4 CCC-3-V 2.0 n _o (589 nm, 20℃) = 1.4871 5 CCGU-3-F 8.0 Δε (20℃, 1kHz) = 4.9 6 CCP-V-1 14.0 ε _‖ (20℃, 1kHz) = 7.7 7 CCP-V2-1 5.0 ε _┴ (20℃, 1 kHz) = 2.8 8 CCPC-34 2.0 γ ₁ (20℃) = 100 mPa·s 9 CCVC-3-V 4.0 _K1 (20℃) = 18.2 pN 10 CDUQU-3-F 8.0 _K3 (20℃) = 20.7 pN 11 CLP-V-1 5.0 V ₀ (20℃) = 2.03 V 12 PGP-2-2V 3.5 13 PGUQU-4-F 2.0 14 PP-1-2V1 3.0 15 PPGU-3-F 0.5 16 PUQU-3-F 4.0 The LC mixture had a _Kav of 16.00 pN and a γ ₁ /K ₁ of 5.49 mPa s/pN.

Mixture Example S11 ( Stabilized by Compound of Formula H-3-1 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M11 99.9% by weight Compound of formula H-3-1 1000 ppm Compared to the unstabilized mixture M11, the addition of 1000 ppm of the compound of formula H-3-1 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M11.

Example M12 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-V 32.0 T(N, I) = 117.6 ℃ 2 CC-3-V1 6.5 Δn (20℃, 589 nm) = 0.1025 3 CCC-3-V 4.0 n _e (589 nm, 20℃) = 1.5910 4 CCGU-3-F 7.0 n _o (589 nm, 20℃) = 1.4885 5 CCP-V-1 15.0 Δε (20℃, 1kHz) = 5.0 6 CCP-V2-1 5.0 ε _‖ (20℃, 1kHz) = 7.8 7 CCPC-33 1.5 ε _┴ (20℃, 1 kHz) = 2.8 8 CCPC-34 2.0 γ ₁ (20℃) = 107 mPa·s 9 CDUQU-3-F 8.0 _K1 (20℃) = 18.7 pN 10 CLP-V-1 5.0 _K3 (20℃) = 21.5 pN 11 DLGU-3-F 4.0 V ₀ (20℃) = 2.04 V 12 PGP-2-2V 4.0 13 PP-1-2V1 3.0 14 PPGU-3-F 0.5 15 PUQU-3-F 2.5 The LC mixture had a _Kav of 16.52 pN and a γ ₁ /K ₁ of 5.72 mPa s/pN.

Mixture Example S12 ( Stabilized by Compound of Formula ST-1-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M12 99.95% by weight Compound of formula ST-1-3 500 ppm The addition of 500 ppm of the compound of formula ST-1-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M12 without affecting the remaining physical properties of the mixture M12.

Example M13 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-V 36.0 T(N, I) = 112.7 ℃ 2 CC-3-V1 5.0 Δn (20℃, 589 nm) = 0.0997 3 CCC-3-V 3.0 n _e (589 nm, 20℃) = 1.5911 4 CCGU-3-F 7.5 n _o (589 nm, 20℃) = 1.4914 5 CCP-V-1 13.0 Δε (20℃, 1kHz) = 4.8 6 CCP-V2-1 4.5 ε _‖ (20℃, 1kHz) = 7.6 7 CCPC-33 1.5 ε _┴ (20℃, 1 kHz) = 2.8 8 CCPC-34 2.0 γ ₁ (20℃) = 97 mPa·s 9 CDUQU-3-F 8.0 _K1 (20℃) = 18.0 pN 10 CLP-V-1 5.0 _K3 (20℃) = 20.5 pN 11 DLGU-3-F 4.0 V ₀ (20℃) = 2.05 V 12 PGP-2-2V 4.5 13 PP-1-2V1 4.0 14 PPGU-3-F 0.5 15 PUQU-3-F 1.5 The LC mixture had a _Kav of 15.83 pN and a γ ₁ /K ₁ of 5.39 mPa s/pN.

Mixture Example S13 ( Stabilized by Compound of Formula ST-1-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M13 99.96% by weight Compound of formula ST-1-3 400 ppm The addition of 400 ppm of the compound of formula ST-1-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M13 without affecting the remaining physical properties of the mixture M13.

Example M14 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 83.6 ℃ 2 CC-3-V 34.5 Δn (20℃, 589 nm) = 0.1335 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6266 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4931 5 CLP-3-T 8.0 Δε (20℃, 1kHz) = 3.8 6 CLP-V-1 1.5 ε _‖ (20℃, 1kHz) = 6.5 7 DGUQU-4-F 6.5 ε _┴ (20℃, 1 kHz) = 2.7 8 DPGU-4-F 2.0 γ ₁ (20℃) = 60 mPa·s 9 PGP-1-2V 4.0 _K1 (20℃) = 19.5 pN 10 PGP-2-2V 5.0 _K3 (20℃) = 16.0 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.40 V 12 PPGU-3-F 0.5 13 PUS-3-2 13.0 The LC mixture had a _Kav of 15.08 pN and a γ ₁ /K ₁ of 3.08 mPa s/pN.

Mixture Example S14 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M14 99.95% by weight Compound of formula ST-2-3 500 ppm The addition of 500 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M14, without affecting the remaining physical properties of the mixture M14.

Example M15 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 85.5 ℃ 2 CC-3-V 35.0 Δn (20℃, 589 nm) = 0.1341 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6262 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4921 5 CLP-3-T 8.0 Δε (20℃, 1kHz) = 3.7 6 CLP-V-1 2.5 ε _‖ (20℃, 1kHz) = 6.4 7 PGP-1-2V 7.5 ε _┴ (20℃, 1 kHz) = 2.7 8 PGP-2-2V 5.0 γ ₁ (20℃) = 63 mPa·s 9 PGUQU-3-F 4.0 _K1 (20℃) = 19.4 pN 10 PGUQU-4-F 3.0 _K3 (20℃) = 16.5 pN 11 PGUQU-5-F 3.0 V ₀ (20℃) = 2.40 V 12 PP-1-2V1 10.0 13 PPGU-3-F 0.5 14 PUS-3-2 6.5 The LC mixture had a _Kav of 15.20 pN and a γ ₁ /K ₁ of 3.25 mPa s/pN.

Mixture Example S15 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M15 99.97% by weight Compound of formula ST-2-3 300 ppm The addition of 300 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M15, without affecting the remaining physical properties of the mixture M15.

Example M16 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 81.6 ℃ 2 CC-3-V 36.5 Δn (20℃, 589 nm) = 0.1337 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6261 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4924 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.4 6 CLY-3-O2 2.0 ε _‖ (20℃, 1kHz) = 6.1 7 PGP-1-2V 7.0 ε _┴ (20℃, 1 kHz) = 2.7 8 PGUQU-3-F 3.0 γ ₁ (20℃) = 60 mPa·s 9 PGUQU-4-F 4.0 _K1 (20℃) = 18.4 pN 10 PGUQU-5-F 2.5 _K3 (20℃) = 16.1 pN 11 PP-1-2V1 9.5 V ₀ (20℃) = 2.47 V 12 PUS-3-2 13.5 The LC mixture had a _Kav of 14.57 pN and a γ ₁ /K ₁ of 3.26 mPa s/pN.

Mixture Example S16 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M16 99.97% by weight Compound of formula ST-2-3 300 ppm The addition of 300 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M16, without affecting the remaining physical properties of the mixture M16.

Example M17 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 APUQU-3-F 4.0 T(N, I) = 87.5 ℃ 2 CC-3-2V1 4.0 Δn (20℃, 589 nm) = 0.1347 3 CC-3-V 33.5 n _e (589 nm, 20℃) = 1.6279 4 CC-3-V1 8.0 n _o (589 nm, 20℃) = 1.4932 5 CCC-3-V 3.0 Δε (20℃, 1kHz) = 3.9 6 CLP-3-T 7.0 ε _‖ (20℃, 1kHz) = 6.6 7 CLP-V-1 5.0 ε _┴ (20℃, 1 kHz) = 2.7 8 PGP-1-2V 9.75 γ ₁ (20℃) = 65 mPa·s 9 PGUQU-3-F 2.75 _K1 (20℃) = 20.1 pN 10 PGUQU-4-F 4.0 _K3 (20℃) = 17.4 pN 11 PP-1-2V1 10.0 V ₀ (20℃) = 2.40 V 12 PPGU-3-F 0.5 13 PUS-3-2 8.5 The LC mixture had a _Kav of 15.85 pN and a γ ₁ /K ₁ of 3.23 mPa s/pN.

Mixture Example S17 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M17 99.96% by weight Compound of formula ST-2-3 400 ppm The addition of 400 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M17, without affecting the remaining physical properties of the mixture M17.

Example M18 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 92.4 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 0.1343 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6277 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4934 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 4.4 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7.1 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 2.7 8 PGP-1-2V 8.5 γ ₁ (20℃) = 72 mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = 22.5 pN 10 PP-1-2V1 10.0 _K3 (20℃) = 19.2 pN 11 PPGU-3-F 0.5 V ₀ (20℃) = 2.40 V 12 PUS-3-2 8.75 The LC mixture had a _Kav of 17.65 pN and a γ ₁ /K ₁ of 3.20 mPa s/pN.

Mixture Example S18 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M18 99.96% by weight Compound of formula ST-2-3 400 ppm The addition of 400 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M18, without affecting the remaining physical properties of the mixture M18.

Example M19 ( Inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 81.9 ℃ 2 CC-3-V 36.5 Δn (20℃, 589 nm) = 0.1331 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6265 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4938 5 CCP-V-1 2.25 Δε (20℃, 1kHz) = 3.5 6 CLP-3-T 7.0 ε _‖ (20℃, 1kHz) = 6.1 7 PGP-1-1(c3) 8.0 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 59 mPa·s 9 PGUQU-4-F 3.0 10 PGUQU-5-F 2.25 11 PP-1-2V1 10.0 12 PUS-3-2 13.0 PGP-1-1(c3)

Mixture Example S19 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M19 99.97% by weight Compound of formula ST-2-3 300 ppm The addition of 300 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M19, without affecting the remaining physical properties of the mixture M19.

Example M20 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 81.9 ℃ 2 CC-3-V 36.5 Δn (20℃, 589 nm) = 0.1331 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6265 4 CCC-3-V 3.0 n _o (589 nm, 20℃) = 1.4938 5 CCP-V-1 2.25 Δε (20℃, 1kHz) = 3.5 6 CLP-3-T 7.0 ε _‖ (20℃, 1kHz) = 6.1 7 PGP-1-2V 8.0 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 59 mPa·s 9 PGUQU-4-F 3.0 10 PGUQU-5-F 2.25 11 PP-1-2V1 10.0 12 PUS-(c5)-2 13.0 PUS-(c5)-2

Mixture Example S20 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M20 99.97% by weight Compound of formula ST-2-3 300 ppm The addition of 300 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M20 without affecting the remaining physical properties of the mixture M20.

Example M21 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 82.8 ℃ 2 CC-3-V 35.75 Δn (20℃, 589 nm) = 0.1341 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6281 4 CCC-3-V 2.0 n _o (589 nm, 20℃) = 1.4941 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.6 6 CLP-V-1 5.5 ε _‖ (20℃, 1kHz) = 6.2 7 PGP-1-2V 6.75 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU(1)-3-F 4.0 γ ₁ (20℃) = 62 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 17.1 pN 10 PGUQU-5-F 3.0 _K3 (20℃) = 14.9 pN 11 PP-1-2V1 10.0 12 PUS-3-2 12.0 The PGUQU(1)-3-F LC mixture had a _Kav of 13.52 pN and a γ ₁ /K ₁ of 3.63 mPa s/pN.

Mixture Example S21 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M21 99.96% by weight Compound of formula ST-2-3 400 ppm Compared to the unstabilized mixture M20, the addition of 400 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M20.

Example M22 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 83.1 ℃ 2 CC-3-V 35.75 Δn (20℃, 589 nm) = 0.1342 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6283 4 CCC-3-V 2.0 n _o (589 nm, 20℃) = 1.4940 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.5 6 CLP-V-1 5.5 ε _‖ (20℃, 1kHz) = 6.1 7 PGP-1-2V 6.75 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 61 mPa·s 9 PGUQU-4-F 3.0 _K1 (20℃) = 17.4 pN 10 PGUQU-(c5)-F 3.0 _K3 (20℃) = 15.3 pN 11 PP-1-2V1 10.0 12 PUS-3-2 12.0 The PGUQU-(c5)-F LC mixture had a _Kav of 13.80 pN and a γ ₁ /K ₁ of 3.51 mPa s/pN.

Mixture Example S22 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M22 99.96% by weight Compound of formula ST-2-3 400 ppm The addition of 400 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M22, without affecting the remaining physical properties of the mixture M22.

Example M23 ( Inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 82.3 ℃ 2 CC-3-V 35.75 Δn (20℃, 589 nm) = 0.1343 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6283 4 CCC-3-V 2.0 n _o (589 nm, 20℃) = 1.4940 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.4 6 CLP-V-1 5.5 ε _‖ (20℃, 1kHz) = 6.0 7 PGP-1-2V 6.75 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 3.0 γ ₁ (20℃) = 60 mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = 17.5 pN 10 PGUQU-5-F 2.0 _K3 (20℃) = 15.3 pN 11 PGUQU-(c3)1-F 3.0 12 PP-1-2V1 10.0 13 PUS-3-2 12.0 The PGUQU-(c3)1-F LC mixture had a _Kav of 13.85 pN and a γ ₁ /K ₁ of 3.43 mPa s/pN.

Mixture Example S23 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M22 99.96% by weight Compound of formula ST-2-3 400 ppm The addition of 400 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M23, without affecting the remaining physical properties of the mixture M23.

Example M24 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 3.0 T(N, I) = 81.5 ℃ 2 CC-3-V 35.75 Δn (20℃, 589 nm) = 0.1327 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.6275 4 CCC-3-V 2.0 n _o (589 nm, 20℃) = 1.4946 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 3.5 6 CLP-V-1 5.5 ε _‖ (20℃, 1kHz) = 6.1 7 PGP-1-2V 6.75 ε _┴ (20℃, 1 kHz) = 2.6 8 PGUQU-3-F 4.0 γ ₁ (20℃) = 60 mPa·s 9 PGUQU-4-F 3.0 10 PGUQU-(c5)-F 3.0 11 PP-1-2V1 7.0 12 PP-1-1(c3) 3.0 13 PUS-3-2 12.0 PGUQU-(c5)-F PP-1-1(c3)

Mixture Example S24 ( Stabilized by Compound of Formula ST-2-3 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M24 99.96% by weight Compound of formula ST-2-3 400 ppm The addition of 400 ppm of the compound of formula ST-2-3 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M24, without affecting the remaining physical properties of the mixture M24.

Example M25 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 88.0 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 4 CCC-3-0 3.0 n _o (589 nm, 20℃) = 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 8 PGP-1-2V 8.5 γ ₁ (20℃) = mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = pN 10 PP-1-2V1 10.0 _K3 (20℃) = pN 11 PPGU-3-F 0.5 V ₀ (20℃) = V 12 PUS-3-2 8.75

Mixture Example S25 ( Stabilized by Compound of Formula ST-1-8 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M25 99.97% by weight Formula ST-1-8 compound 300 ppm The addition of 300 ppm of the compound of formula ST-1-8 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M25, without affecting the remaining physical properties of the mixture M25. ST-1-8

Example M26 ( Inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 88.0 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 4 CCC-2-V 3.0 n _o (589 nm, 20℃) = 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 8 PGP-1-2V 8.5 γ ₁ (20℃) = mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = pN 10 PP-1-2V1 10.0 _K3 (20℃) = pN 11 PPGU-3-F 0.5 V ₀ (20℃) = V 12 PUS-3-2 8.75

Mixture Example S26 ( Stabilized by Compound of Formula ST-2-8 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M26 99.97% by weight Compound of formula ST-2-8 300 ppm ST-2-8 The addition of 300 ppm of the compound of formula ST-2-8 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M26, without affecting the remaining physical properties of the mixture M26.

Example M27 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 88.0 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 4 CCC-2-V 3.0 n _o (589 nm, 20℃) = 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 8 PGP-1-2V 8.5 γ ₁ (20℃) = mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = pN 10 PP-1-2V1 10.0 _K3 (20℃) = pN 11 PPGU-3-F 0.5 V ₀ (20℃) = V 12 PUS-3-2 8.75

Mixture Example S27 ( Stabilized by Compound of Formula ST-4-1 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M27 99.94% by weight Compound of formula ST-4-1 600 ppm ST-4-1 The addition of 600 ppm of the compound of formula ST-4-1 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M27, without affecting the remaining physical properties of the mixture M27.

Example M28 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CCP-2F.F.F 9.0 T(N, I) = 84.0 ℃ 2 CCP-20CF3 6.0 Δn (20℃, 589 nm) = 0.0841 3 CCZU-2-F 4.0 n _e (589 nm, 20℃) = 1.5621 4 CCZU-3-F 15.0 n _o (589 nm, 20℃) = 1.4780 5 CCZU-5-F 2.0 Δε (20℃, 1kHz) = 10.2 6 CCP-V-1 8.0 ε _‖ (20℃, 1kHz) = 14.0 7 CDU-2-F 7.5 ε _┴ (20℃, 1 kHz) = 3.8 8 PGU-2-F 2.5 γ ₁ (20℃) = 90 mPa·s 9 PUQU-2-F 6.0 _K1 (20℃) = 12.9 pN 10 PUQU-3-F 8.5 _K3 (20℃) = 14.2 pN 11 CC-3-V1 11.0 12 CC-5-V 10.0 13 CCH-35 5.5 14 CCC-3-V 5.0

Mixture Example S28 ( Stabilized by Compound of Formula ST-4-2 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M28 99.94% by weight Compound of formula ST-4-2 600 ppm ST-4-2 The addition of 600 ppm of the compound of formula ST-4-2 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M28, without affecting the remaining physical properties of the mixture M28.

Example M29 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CCP-2F.F.F 9.0 T(N, I) = 84.0 ℃ 2 CCP-20CF3 6.0 Δn (20℃, 589 nm) = 0.0841 3 CCZU-2-F 4.0 n _e (589 nm, 20℃) = 1.5621 4 CCZU-3-F 15.0 n _o (589 nm, 20℃) = 1.4780 5 CCZU-5-F 2.0 Δε (20℃, 1kHz) = 10.2 6 CCP-V-1 8.0 ε _‖ (20℃, 1kHz) = 14.0 7 CDU-2-F 7.5 ε _┴ (20℃, 1 kHz) = 3.8 8 PGU-2-F 2.5 γ ₁ (20℃) = 90 mPa·s 9 PUQU-2-F 6.0 _K1 (20℃) = 12.9 pN 10 PUQU-3-F 8.5 _K3 (20℃) = 14.2 pN 11 CC-3-V1 11.0 12 CC-5-V 10.0 13 CCH-35 5.5 14 CCC-3-V 5.0

Mixture Example S29 ( Stabilized by Compound of Formula ST-4-2 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M29 99.95% by weight Compound of formula ST-4-2 500 ppm The addition of 500 ppm of the compound of formula ST-4-2 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M29, without affecting the remaining physical properties of the mixture M29.

Example M30 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CCP-2F.F.F 7.5 T(N, I) = 76.5 ℃ 2 CCP-30CF3 2.5 Δn (20℃, 589 nm) = 0.0975 3 CGZP-2-OT 10.0 n _e (589 nm, 20℃) = 1.5780 4 CGZP-3-OT 4.0 n _o (589 nm, 20℃) = 1.4805 5 CCZU-2-F 2.0 Δε (20℃, 1kHz) = 12.2 6 CDU-2-F 9.0 ε _‖ (20℃, 1kHz) = 16.8 7 CDU-3-F 9.0 ε _┴ (20℃, 1 kHz) = 4.6 8 CDU-5-F 9.0 γ ₁ (20℃) = 105 mPa·s 9 PGU-2-F 9.0 _K1 (20℃) = 11.9 pN 10 PGU-3-F 9.0 _K3 (20℃) = 10.8 pN 11 CC-3-V1 11.0 12 CC-5-V 9.5 13 CCH-35 5.0 14 CCC-3-V 4.5

Mixture Example S30 ( Stabilized by Compound of Formula ST-4-1 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M30 99.95% by weight Compound of formula ST-4-1 500 ppm The addition of 500 ppm of the compound of formula ST-4-1 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M30 without affecting the remaining physical properties of the mixture M30.

Example M31 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 91.0 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 4 CCEC-1-3 3.0 n _o (589 nm, 20℃) = 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 8 PGP-1-2V 8.5 γ ₁ (20℃) = mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = pN 10 PP-1-2V1 10.0 _K3 (20℃) = pN 11 PPGU-3-F 0.5 12 PUS-3-2 8.75

Mixture Example S31 ( Stabilized by Compound of Formula H-3-2 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M31 99.99% by weight Compound of formula H-3-2 100 ppm Compared to the unstabilized mixture M31, the addition of 100 ppm of the compound of formula H-3-2 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M31. H-3-2

Example M32 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 91.0 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 4 CCEC-3-1 3.0 n _o (589 nm, 20℃) = 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 8 PGP-1-2V 8.5 γ ₁ (20℃) = mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = pN 10 PP-1-2V1 10.0 _K3 (20℃) = pN 11 PPGU-3-F 0.5 12 PUS-3-2 8.75

Mixture Example S32 ( Stabilized by Compound of Formula H-3-4 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M32 99.99% by weight Formula H-3-4 compound 100 ppm Compared to the unstabilized mixture M32, the addition of 100 ppm of the compound of formula H-3-4 significantly improved the VHR ₁₀₀ after UV exposure without affecting the remaining physical properties of the mixture M32. H-3-4

Example M33 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 4.0 T(N, I) = 91.0 ℃ 2 CC-3-V 33.25 Δn (20℃, 589 nm) = 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 4 CCEC-4-1 3.0 n _o (589 nm, 20℃) = 5 CLP-3-T 7.0 Δε (20℃, 1kHz) = 6 CLP-V-1 5.0 ε _‖ (20℃, 1kHz) = 7 DLGU-3-F 10.0 ε _┴ (20℃, 1 kHz) = 8 PGP-1-2V 8.5 γ ₁ (20℃) = mPa·s 9 PGUQU-4-F 2.0 _K1 (20℃) = pN 10 PP-1-2V1 10.0 _K3 (20℃) = pN 11 PPGU-3-F 0.5 12 PUS-3-2 8.75

Mixture Example S33 ( Stabilized by Compound of Formula H-3-6 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M33 99.995% by weight Formula H-3-6 compound 50 ppm The addition of 50 ppm of the compound of formula H-3-6 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M33 without affecting the remaining physical properties of the mixture M33. H-3-6

Example M34 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 7.5 T(N, I) = ℃ 2 CC-3-V 20.5 Δn (20℃, 589 nm) = 1.5614 3 CC-3-V1 14.5 n _e (589 nm, 20℃) = 1.4806 4 CCOC-3-3 2.0 n _o (589 nm, 20℃) = 0.0808 5 CCOC-4-3 1.0 Δε (20℃, 1kHz) = 6.4 6 CCP-V-1 7.5 ε _‖ (20℃, 1kHz) = 2.7 7 CCP-V2-1 7.5 ε _┴ (20℃, 1 kHz) = 3.7 8 CCQU-3-F 7.0 γ ₁ (20℃) = 112 mPa·s 9 CDUQU-3-F 3.0 _K1 (20℃) = 20.1 pN 10 CH-33 3.0 _K3 (20℃) = 22.3 pN 11 CH-35 3.0 12 CLP-3-T 5.5 13 CLP-V-1 3.5 14 CLU-3-F 14.5

Mixture Example S34 ( Stabilized by Compound of Formula H-3-7 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M34 99.98% by weight Compound of formula H-3-7 200 ppm The addition of 200 ppm of the compound of formula H-3-7 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M34 without affecting the remaining physical properties of the mixture M34. H-3-7

Example M35 ( inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 8.0 T(N, I) = 104.1 ℃ 2 CC-3-V 20.5 Δn (20℃, 589 nm) = 1.5634 3 CC-3-V1 15.0 n _e (589 nm, 20℃) = 1.4801 4 CCP-V-1 8.0 n _o (589 nm, 20℃) = 0.0833 5 CCP-V2-1 8.0 Δε (20℃, 1kHz) = 7.0 6 CCQU-3-F 9.0 ε _‖ (20℃, 1kHz) = 2.7 7 CDUQU-3-F 4.5 ε _┴ (20℃, 1 kHz) = 4.3 8 CH-33 3.0 γ ₁ (20℃) = 101 mPa·s 9 CLP-3-T 4.0 _K1 (20℃) = 19.3 pN 10 CLP-V-1 5.0 _K3 (20℃) = 22.5 pN 14 CLU-3-F 15.0

Mixture Example S35 ( Stabilized by Compound of Formula H-3-9 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M35 99.995% by weight Compound of formula H-3-9 50 ppm The addition of 50 ppm of the compound of formula H-3-6 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M35 without affecting the remaining physical properties of the mixture M35. H-3-9

Example M36 ( Inventive ) Nematic LC medium is formulated as follows: Composition Nature No. Compound Concentration, weight % 1 CC-3-2V1 8.0 T(N, I) = 106.6 ℃ 2 CC-3-V 29.0 Δn (20℃, 589 nm) = 1.5637 3 CC-3-V1 8.0 n _e (589 nm, 20℃) = 1.4823 4 CCOC-3-3 3.0 n _o (589 nm, 20℃) = 0.0814 5 CCP-3-1 3.0 Δε (20℃, 1kHz) = 6.2 6 CCP-V-1 8.0 ε _‖ (20℃, 1kHz) = 2.6 7 CCP-V2-1 8.0 ε _┴ (20℃, 1 kHz) = 3.6 8 CCVC-3-V 2.0 γ ₁ (20℃) = 88 mPa·s 9 CDUQU-3-F 8.0 _K1 (20℃) = 20.0 pN 10 CH-33 3.0 _K3 (20℃) = 22.0 pN 11 CLP-3-T 6.0 12 CLP-V-1 4.5 13 CLU-3-F 8.0 14 PCH-302 1.5

Mixture Example S36 ( Stabilized by Compound of Formula H-3-10 ) The nematic LC mixture according to the present invention is prepared as follows: Mixture M36 99.995% by weight Compound of formula H-3-10 50 ppm The addition of 50 ppm of the compound of formula H-3-6 significantly improved the VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M36 without affecting the remaining physical properties of the mixture M36. H-3-10

Claims (18)

A liquid crystal medium, characterized in that the liquid crystal medium comprises one or more compounds of formula I wherein the individual substituents have the following meanings, identically or differently and independently of one another, on each occurrence: R ¹¹ and R ¹² each independently represent an H atom, an alkyl or alkoxy group having 1 to 12 C atoms, or an alkenyl or alkenyloxy group having 2 to 12 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom, or a cycloalkyl or cycloalkoxy group having 3 to 12 C atoms, one or more H atoms thereof may be replaced by a halogen atom, preferably a cyclopentyl or cyclopentyloxy group; Z ¹ represents a single bond, -CH ₂ -CH ₂ - or -COO-; and one or more compounds selected from the group consisting of the following formulae LP1 and LP2 wherein the individual substituents have the following meanings on each occurrence, identically or differently and independently of one another: R ⁰ is an alkyl or alkoxy group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom; R ² is an alkyl or alkoxy group having 1 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom; X ² is a F atom or an alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl or alkenyloxy group having 2 to 6 C atoms, wherein one or more H atoms are replaced by an F atom; Y ⁰ H or CH ₃ ; L ¹ and L ² are independently H, F or Cl; Y ⁰ H or CH ₃ ; m and n are independently 0, 1 or 2. The liquid crystal medium of claim 1, wherein the one or more compounds of formula I are described by formula I-1: wherein R ¹¹ and R ¹² each independently represent an H atom, an alkyl or alkoxy group having 1 to 6 C atoms, or an alkenyl or alkenyloxy group having 2 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO-, wherein the O atoms are not directly connected to each other and one or more H atoms thereof are replaced by a halogen atom, or a cycloalkyl or cycloalkoxy group having 3 to 6 C atoms, wherein one or more H atoms thereof are replaced by a halogen atom. The liquid crystal medium of claim 1, wherein the one or more compounds of formula LP1 and LP2 are described by formula LP1-1 and LP2-1: wherein R ⁰ is an alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl group having 2 to 12 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in a manner that the O atoms are not directly connected to each other, and one or more H atoms thereof may be replaced by a halogen atom; R ² is an alkyl or alkoxy group having 1 to 6 C atoms, wherein one or more CH ₂ groups are optionally replaced by -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-, , , , , , -O-, -CO-O- or -O-CO- is substituted in such a way that the O atoms are not directly linked to each other, and one or more H atoms thereof may be replaced by a halogen atom; X ² F atom or an alkyl or alkoxy group having 1 to 3 C atoms or an alkenyl or alkenyloxy group having 2 or 3 C atoms, wherein one or more H atoms are replaced by a F atom; and Y ⁰ H or CH ₃ . The liquid crystal medium of any one of claims 1 to 3, wherein the liquid crystal medium comprises one or more compounds selected from the group consisting of the following formulae II and III: where the individual substituents, independently of one another and identically or differently on each occurrence, have the following meanings: R ⁰ one of the meanings given for R ¹¹ in claim 1; L ^{1 - 6} are independently H or F; X ⁰ are independently F, Cl, halogenated alkyl, halogenated alkenyl, halogenated alkoxy or halogenated alkenyloxy having up to 6 C atoms; and Y ⁰ H or CH ₃ . The liquid crystal medium of claim 4, wherein the one or more compounds of formula II are selected from the following sub-formulas: wherein R ⁰ and X ⁰ have the meanings given in Formula II. The liquid crystal medium of claim 4, wherein the one or more compounds of formula III are selected from the following sub-formulas: wherein R ⁰ and X ⁰ have the meanings given in Formula III. The liquid crystal medium of any one of claims 1 to 3, wherein the liquid crystal medium comprises one or more compounds selected from the following formulae Z1 to Z7: Herein, "alkyl" and "alkyl*" represent C _1-6 -alkyl and "alkenyl" and "alkenyl*" represent C _2-6 -alkenyl. The liquid crystal medium of any one of claims 1 to 3, wherein the liquid crystal medium comprises one or more compounds selected from the group consisting of: wherein R ¹ and R ² each independently represent n-alkyl, alkoxy, oxoalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, "alkenyl" represents C _2-6 -alkenyl, and L ¹ has the meaning indicated in claim 1. The liquid crystal medium of any one of claims 1 to 3, wherein the liquid crystal medium further comprises one or more compounds selected from the group consisting of: wherein R ⁰ , X ⁰ , L ¹ , L ² and Y ⁰ have the meanings indicated in claim 4, L ³ and L ⁴ independently have one of the meanings given for L ¹ ; and Z ⁰ represents -C ₂ H ₄ -, -(CH ₂ ) ₄ -, -CH=CH-, -CF=CF-, -C ₂ F ₄ -, -CH ₂ CF ₂ -, -CF ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -COO-, -CF ₂ O- or -OCF ₂ -, which is also a single bond in formulae V and VI; and s represents 0 or 1. The liquid crystal medium of any one of claims 1 to 3, wherein the liquid crystal medium comprises one or more compounds selected from the group consisting of: wherein R ⁰ , L ^{1 - 4} , Y ⁰ and X ⁰ each independently have one of the meanings indicated in claim 4. The liquid crystal medium of any one of claims 1 to 3, wherein the liquid crystal medium comprises one or more compounds selected from the group consisting of: wherein ^R1 and ^X0 have the meanings of ^R0 and ^X0 indicated in claim 4. A liquid crystal medium as in any one of claims 1 to 3, wherein the liquid crystal medium comprises one or more compounds of formula I, LP1 and LP2 and one or more compounds selected from the group consisting of formula Z1, Z2, Z3, Z4, Z5, II, III, IV, VI, XIV, XX, XXIII, XXIX, XVI, XVIIa, XVIIb and XVIIc. A liquid crystal medium as claimed in any one of claims 1 to 3, wherein the liquid crystal medium further comprises one or more polymerizable compounds. A method for preparing a liquid crystal medium as claimed in any one of claims 1 to 13, characterized in that one or more compounds of formula I and one or more compounds of formula LP1 and/or LP2 are mixed with one or more mesogen compounds and, if necessary, one or more polymerizable compounds and/or one or more additives. A use of a liquid crystal medium as claimed in any one of claims 1 to 13 for electro-optical purposes. An electro-optical liquid crystal display comprising a liquid crystal medium as claimed in any one of claims 1 to 13. An electro-optical liquid crystal display as claimed in claim 15, wherein the electro-optical liquid crystal display is TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, SA-HB-FFS, SA-XB-FS, polymer-stabilized SA-HB-FFS, polymer-stabilized SA-XB-FFS, positive VA or positive PS-VA display. An electro-optical liquid crystal display as claimed in claim 16, wherein the electro-optical liquid crystal display is a FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, IPS or PS-IPS display.