CN118516118A

CN118516118A - Liquid-crystalline medium

Info

Publication number: CN118516118A
Application number: CN202310136286.5A
Authority: CN
Inventors: S·C·洛特; 李熙规; 杨明辉
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 2023-02-20
Filing date: 2023-02-20
Publication date: 2024-08-20
Also published as: TW202449121A; WO2024175518A1

Abstract

The invention relates to liquid crystal (LC) media and to energy-saving liquid crystal displays (LCDs) containing these media, particularly to displays addressed by active matrices and particularly to 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 LC displays.

Description

Liquid-crystalline medium

Technical Field

The present invention relates to Liquid Crystal (LC) media and to energy efficient Liquid Crystal Displays (LCDs) containing these media, in particular to displays addressed by 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 stabilized SA-HB-FFS, polymer stabilized SA-XB-FFS, positive VA or positive PS-VA type. In a preferred embodiment, the LC medium has a positive dielectric anisotropy.

Background

Liquid Crystal Displays (LCDs) are used in many fields for information display. LCDs are used for both direct view and projection displays. The electro-optical modes used are, for example, twisted Nematic (TN), super Twisted Nematic (STN), optically Compensated Bend (OCB) and Electrically Controlled Birefringence (ECB) modes and their variants, among others. All of these modes utilize an electric field generated substantially perpendicular to the substrate and LC layer.

In addition to these modes, there are electro-optical modes that utilize an electric field that is substantially parallel to the substrate or LC layer. For example, WO 91/10936 discloses LC displays 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 since then it is known as in-plane switching (IPS) displays. The principle of operation of such a display is described, for example, by R.A. Soref in Journal of APPLIED PHYSICS, journal of applied physics, volume 45, 12, pages 5466-5468 (1974).

The IPS display contains an LC layer between two substrates with an in-plane orientation, wherein the two electrodes are arranged on only one of the two substrates and preferably have an interdigitated comb structure. When a voltage is applied to the electrodes, an electric field is generated between them with a significant component parallel to the LC layer. This results in a realignment of LC molecules in the layer 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 s.h.jung et al, jpn.j.appl.Phys. [ journal of applied physics ], volume 43, stage 3, 2004,1028) which contain two electrodes on the same substrate, one of which is structured in a comb-like fashion and the other of which is unstructured. Thereby creating a strong so-called "fringe field", i.e. a strong electric field near the edges of the electrodes, and an electric field having both a strong vertical component and also a strong horizontal component throughout the cartridge. FFS displays have low contrast viewing angle dependence. FFS displays typically contain an LC medium with positive dielectric anisotropy, and an alignment layer, typically polyimide, that provides planar alignment for the molecules of the LC medium.

IPS and FFS electro-optic mode liquid crystal displays are particularly suitable for modern desktop monitors, televisions and multimedia applications. The LC medium according to the invention is preferably used in a display of this type. Typically, dielectrically positive LC media with a fairly low value of dielectric anisotropy are used in FFS displays, but in some cases LC media with dielectric anisotropy of only about 3 or even lower are also used in IPS displays.

Further improvements have been achieved by the HB-FFS mode. One of the unique features of the HB-FFS mode is that it enables higher transmittance compared to conventional FFS techniques, which allows the panel to be operated with less energy 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 in the 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 drawbacks. Among other drawbacks, most of them result in disadvantageously long addressing times, have insufficient resistivity values, and/or require excessive operating voltages. Improvements in both handling characteristics and also in shelf life are necessary here.

FFS and IPS displays may operate as Active Matrix Displays (AMD) or Passive Matrix Displays (PMD). In the case of active matrix displays, the individual pixels are usually 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 usually addressed by multiplexing methods as known from the prior art.

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

Typical applications of in-plane switching (IPS) and Fringe Field Switching (FFS) technologies are monitors, notebook computers, televisions, mobile phones, tablet PCs, etc.

Both IPS and FFS techniques have certain advantages over other LCD techniques, such as, for example, vertical Alignment (VA) techniques, e.g., wide viewing angle dependence of contrast.

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

Until now, it was not possible to design a suitable LC medium with high contrast, e.g. high elastic constants K ₁ and K _av, low temperature stability and low response time. Thus, the overall image quality in such devices still needs to be further improved.

Disclosure of Invention

It is an object of the present invention to provide LC media, in particular for energy-saving FFS and IPS displays, but also for TN, positive VA or STN displays, and in particular for active matrix displays like those addressed by TFTs, which do not exhibit the disadvantages indicated above or only to a lesser extent, and which have a high average elastic constant K _av in combination with a low response time parameter (y ₁/K₁) and a low rotational viscosity, relatively low birefringence an. In addition, they are required to have high specific resistance, low threshold voltage, high dielectric anisotropy, good Low Temperature Stability (LTS), fast response time, and to be capable of achieving high luminance. In the case of FFS displays, there is a need to further optimize response time, contrast, brightness and reliability. However, it was found that prior art LC materials generally do not meet all of these requirements at the same time.

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

It has now surprisingly been found that LC media according to the invention comprise a combination of compounds having the formula I, LP1 and/or LP2

Wherein the substituents are as defined in claim 1

Several significant improvements are shown, especially when used in FFS mode displays like high average elastic constant K _av, low response time parameter (y ₁/K₁) combined with low rotational viscosity and good solubility, and enabling fast response times.

Furthermore, the LC medium according to the present invention has a high clearing point, excellent Low Temperature Stability (LTS), and provides optimal moving picture quality and improved overall image quality, particularly high contrast.

The invention relates to an LC medium, characterized in that it comprises one or more compounds of formula I

Wherein the individual substituents are identical or different on each occurrence and each independently of the other have the following meanings:

R ¹¹ and R ¹² each independently of the other represent a H atom an alkyl or alkoxy group having 1 to 12C atoms or an alkenyl or alkenyloxy group having 2 to 12C atoms (wherein one or more CH ₂ groups are optionally substituted with-c≡c-, -CF ₂O-、-OCF₂ -, -ch=ch- -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms), or cycloalkyl or cycloalkoxy groups having 3 to 12C atoms wherein one or more H atoms may be replaced by halogen atoms, preferably cyclopentyl or cyclopentyloxy,

Z ¹ represents a single bond, -CH=CH-, -CH ₂-CH₂-、-CH₂ O-, or-COO-; and

One or more compounds selected from the group consisting of the following formulas LP1 and LP2

Preferably

Most preferably

R ⁰ is an alkyl or alkoxy group having 1 to 12C atoms or an alkenyl group having 2 to 12C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-,-O-, -CO-O-or-O-CO-substitution in such a way that O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms,

R ² is alkyl or alkoxy having 1 to 6C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms,

X ² F atom or alkyl or alkoxy having 1 to 6C atoms or alkenyl or alkenyloxy having 2 to 6C atoms, wherein one or more H atoms are replaced by F atoms,

L ¹ and L ² are, independently of one another, H, F or Cl,

Y ⁰ H or CH ₃, and

N and m independently of one another represent 0, 1 or 2.

The LC medium according to the invention is particularly suitable for use in FFS, HB-FFS, XB-FFS and IPS mode LC displays based on dielectrically positive liquid crystals and polymer-stabilised variants thereof.

The invention further relates to the use of LC media 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 electro-optic LC displays, in particular 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 displays, preferably FFS, HB-FFS, IPS, PS-HB-FFS or PS-IPS displays, containing LC media as described above and below.

In the present application, all atoms also include their isotopes. In some embodiments, one or more hydrogen atoms (H) may optionally be replaced with deuterium (D); the high degree of deuteration enables or simplifies analytical determination of the compounds, especially at low concentrations.

In formulas I, LP and LP2, if R ⁰、R¹¹、R¹² and R ² represent alkyl and/or alkoxy, they may be straight-chain or branched. It is preferably linear, has 2, 3, 4, 5 or 6C atoms and preferably represents ethyl, propyl, butyl, pentyl, hexyl, ethoxy, propoxy, butoxy, pentoxy or hexoxy, in addition to methyl, methoxy. R ⁰ preferably represents a straight-chain alkyl group having 1 to 6C atoms or an alkenyl group having 2 to 6C atoms.

Oxaalkyl preferably denotes straight-chain 2-oxapropyl (=methoxymethyl), 2- (=ethoxymethyl) or 3-oxabutyl (=2-methoxyethyl), 2-, 3-or 4-oxapentyl, 2-, 3-, 4-or 5-oxahexyl.

If R ⁰、R¹¹、R¹² or R ² represents an alkoxy or oxaalkyl group, it may also contain one or more further oxygen atoms, provided that the oxygen atoms are not directly connected to one another.

In another preferred embodiment, one or more of R ⁰、R¹¹、R¹² and R ² is selected from -S ¹-F、-O-S¹-F、-O-S₁-O-S₂, 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 very preferably one or more of R ⁰、R¹¹、R¹² and R ² are selected from the group consisting of -OCH₂OCH₃、-O(CH₂)₂OCH₃、-O(CH₂)₃OCH₃、-O(CH₂)₄OCH₃、-O(CH₂)₂F、-O(CH₂)₃F、-O(CH₂)₄F A group of groups.

If R ⁰、R¹¹、R¹² or R ² represents alkenyl, it may be straight or branched. It is preferably linear and has 2 to 10C atoms. Thus, it particularly denotes vinyl, prop-1-enyl or prop-2-enyl, but-1-enyl, but-2-enyl or but-3-enyl, pent-1-enyl, pent-2-enyl, pent-3-enyl or-4-enyl, hex-1-enyl, hex-2-enyl, hex-3-enyl, hex-4-enyl or hex-5-enyl, hept-1-enyl, hept-2-enyl, hept-3-enyl, hept-4-enyl, hept-5-enyl or hept-6-enyl, oct-1-enyl, oct-2-enyl, oct-3-enyl, oct-4-enyl, oct-5-enyl, oct-6-enyl, non-1-enyl, non-2-enyl, non-3-enyl, non-4-enyl, non-6-enyl, non-7-enyl or non-8-enyl, dec-1-enyl, dec-2-enyl, dec-3-enyl, dec-6-enyl or dec-8-enyl.

If R ⁰、R¹¹、R¹² or R ² represents an alkyl or alkenyl group which is at least monosubstituted by halogen, the group is preferably straight-chain and the halogen is preferably F or Cl. In the case of polysubstitution, halogen is preferably F. The resulting groups also include perfluorinated groups. In the case of monosubstituted, the fluorine or chlorine substituent may be in any desired position, but is preferably in the ω -position.

In formula LP2, X ² is preferably an F atom or a mono-or polyfluorinated alkyl or alkoxy group having 1, 2 or 3C atoms or a mono-or polyfluorinated alkenyl group having 2 or 3C atoms. X ² is particularly preferably F、CF₃、CHF₂、OCF₃、OCHF₂、OCFHCF₃、OCFHCHF₂、OCFHCHF₂、OCF₂CH₃、OCF₂CHF₂、OCF₂CHF₂、OCF₂CF₂CHF₂、OCF₂CF₂CHF₂、OCFHCF₂CF₃、OCFHCF₂CHF₂、OCF₂CF₂CF₃、OCH＝CF₂ or ch=cf ₂, very particularly preferably F or CF ₃, furthermore OCF ₃、OCF＝CF₂、OCHF₂ or och=cf ₂.

In the compounds of formula I and its subformulae, R ¹¹、R¹² preferably represents a straight-chain alkyl group having 1 to 6C atoms or an alkenyl group having 2 to 6C atoms, very 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 compounds having formula I may be selected from those of the following formulas I-1 to I-5:

wherein the method comprises the steps of

R ¹¹ and R ¹² each independently of the other represent a H atom an alkyl or alkoxy group having 1 to 6C atoms or an alkenyl or alkenyloxy group having 2 to 6C atoms (wherein one or more CH ₂ groups are optionally substituted with-c≡c-, -CF ₂O-、-OCF₂ -, -ch=ch- -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms, preferably F atoms), or cycloalkyl or cycloalkoxy groups having 3 to 6C atoms (wherein one or more H atoms may be replaced by halogen atoms), preferably cyclopentyl or cyclopentyloxy.

Although the choice of substituents R ¹¹ and R ¹² in formula I is not particularly limited, it is particularly advantageous to choose R ¹¹ and R ¹² to be alkyl or cycloalkyl having 1 to 6C atoms, wherein R ¹ selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, cyclopentyl is particularly preferred. R ¹¹ and R ¹² may also advantageously be 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, it has been shown that it is very advantageous to select the following compounds of formula I:

Wherein "alkyl" and "alkyl" represent C _1-6 -alkyl,

"Cycloalkyl" means C _3-6 -cycloalkyl.

The use of compounds having the formula I-1, in particular those having the formulae I-1-1 to I-1-11, is most advantageous with respect to the overall combination of features of the resulting medium.

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

The compounds having the general formulae LP1 and LP2 may be represented by one of the following:

wherein the method comprises the steps of

R ⁰ is alkyl or alkoxy having 1 to 12C atoms (wherein one or more CH ₂ groups are optionally interrupted by-C.ident.C-, -CF ₂O-、-OCF₂ - -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to one another and wherein one or more H atoms may be replaced by halogen atoms), preferably alkyl having 1 to 4C atoms, alkenyl or alkenyloxy having 2 to 6C atoms or cycloalkyl or cycloalkoxy having 3 to 6C atoms, with vinyl, allyl or cyclopentyl being particularly preferred,

N represents 1,2, 3, 4 or 5, and

M represents 1,2,3 or 4.

In further embodiments, the one or more compounds having formulas LP1 and LP2 are described by formulas LP1-1 and LP2-1 below:

wherein the method comprises the steps of

R ⁰ is alkyl or alkoxy having 1 to 6C atoms or alkenyl having 2 to 6C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-,-O-, -CO-O-or-O-CO-substitution in such a way that O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms,

R ² is an alkyl group having 1 to 6C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms,

X ² F atom or alkyl or alkoxy having 1 to 3C atoms or alkenyl or alkenyloxy having 2 or 3C atoms, wherein one or more H atoms are replaced by F atoms, 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 Y ⁰ is H or CH ₃, preferably H.

Very preferred are compounds of the formulae LP1-1a, LP1-1b and LP1-1c, most preferred are compounds of the formula LP1-1 a.

Particularly preferred compounds of formula LP2 are those selected from the group consisting of the following subformulae:

Wherein Y ⁰ is H or CH ₃, preferably H.

Very preferred are compounds having the formulae LP2-1a, LP2-1b, LP2-1c, LP2-1d and LP2-1i, most preferred are compounds having the formula LP2-1 b.

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

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

Additional mesogenic component

In a preferred embodiment, the LC medium may further comprise one or more compounds selected from the following formulae II and III:

wherein the individual substituents independently of one another and identically or differently at each occurrence have the following meanings:

R ⁰ is one of the meanings given for R ¹¹ and R ¹²,

X ⁰, independently of one another, F, cl, haloalkyl, haloalkenyl, haloalkoxy or haloalkenoxy having up to 6C atoms,

L ^1-6, independently of one another, H or F, and

Y ⁰ H or CH ₃.

Preferred compounds of formulae II and III are those in which Y ⁰ is H.

Further preferred compounds of formulae II and III are those wherein R ⁰ represents an alkyl group having 1 to 6C 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 having a formula selected from the following subformulae:

Wherein R ⁰ and X ⁰ have the meanings given in formula II.

Preferred compounds are those of the formulae II-1, II-2 and II-3, very particularly preferred are those of the formulae II-1 and II-2.

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

In one embodiment, the LC medium contains one or more compounds having formula II or subformulae thereof as described above and below, wherein Y ⁰ is CH ₃. 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 the formulae IIA-1, IIA-2 and IIA-3, very particularly preferred are those of the formulae IIA-1 and IIA-2.

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

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

In a further preferred embodiment, the LC medium comprises one or more compounds having formula III selected from the following subformulae:

Wherein R ⁰ and X ⁰ have the meanings given in formula II.

Preferred compounds are those having the formulas III-1, III-4, III-6, III-16, III-19 and III-20.

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

The LC medium may contain one or more compounds having formula III or its subformulae as described above and below, wherein Y ⁰ is CH ₃. Very preferably, the medium according to this preferred embodiment comprises one or more compounds having the formula III selected from the following subformulae:

wherein R ⁰ and X ⁰ have the meanings given in formula III.

Preferred compounds are those having the formulas IIIA-1, IIIA-4, IIIA-6, IIIA-16, IIIA-19 and IIIA-20.

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

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

In a further preferred embodiment, the LC medium may additionally comprise one or more compounds selected from the following formulae:

wherein the method comprises the steps of

R ⁰、X⁰、L^1-4 and Y ⁰ have the meanings indicated in formulae II and III,

Z ⁰ represents -C₂H₄-、-(CH₂)₄-、-CH＝CH-、-CF＝CF-、-C₂F₄-、-CH₂CF₂-、-CF₂CH₂-、-CH₂O-、-OCH₂-、-COO- or-OCF ₂ -, in which case a single bond is also represented in formulae V and VI, -CF ₂ O-, in formulae V and VIII, and

S represents 0 or 1.

The compound having formula IV is preferably selected from the following formulae:

wherein R ⁰ and X ⁰ have the meanings indicated in formulae II and III.

R ⁰ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F or OCF ₃, furthermore ocf=cf ₂ or Cl.

The compound having formula IVa is preferably represented by the following subformula:

the compound having formula IVb is preferably represented by the following formula:

the compound having 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.

One or more compounds of the formula IVc, in particular of the formula IVc-1, are preferably used in the LC medium according to the invention in an amount of from 1% to 20% by weight, particularly preferably from 2% to 15% by weight.

The compound having formula V is preferably selected from the following subformulae:

Wherein R ⁰ and X ⁰ have the meanings indicated in formula II.

R ⁰ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F and OCF ₃, furthermore OCHF ₂、CF₃、OCF＝CF₂ and och=cf ₂.

The compound having formula VI is preferably selected from the following subformulae:

Wherein R ⁰ and X ⁰ have the meanings indicated in formula II.

R ⁰ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F, further OCF ₃、CF₃、CF＝CF₂、OCHF₂ and och=cf ₂;

the compound having formula VII is preferably selected from the following subformulae:

Wherein R ⁰ and X ⁰ have the meanings indicated in formula II.

R ⁰ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F, in addition OCF ₃、OCHF₂ and och=cf ₂.

In some embodiments, the LC medium further comprises one or more compounds selected from the following formulas:

wherein the method comprises the steps of

R ⁰ and X ⁰ each independently of one another have one of the meanings indicated in formula II,

L ^1-4 each independently of the other represents H or F,

Y ⁰ represents H or CH ₃, preferably H,

X ⁰ is preferably F, cl, CF ₃、OCF₃ or OCHF ₂,

R ⁰ preferably represents alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6C 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 LP 1. R ⁰ preferably represents a linear alkyl radical, in particular ethyl, n-propyl, n-butyl or n-pentyl radical and very particularly preferably n-propyl.

One or more compounds of the formula XX, in particular of the formula XXa, are preferably used in the LC medium according to the invention in amounts of from 0% to 15% by weight, particularly preferably from 1% to 10% by weight.

Very preferably, the LC medium according to the invention comprises one or more compounds of formula XXIa:

One or more compounds of the formula XXI, in particular of the formula XXIa, are preferably used in the LC medium according to the invention in amounts of from 1% to 15% by weight, particularly preferably from 2% to 10% by weight.

It is further preferred that the LC medium according to the invention comprises one or more compounds of formula XXIIIa:

One or more compounds of the formula XXIII, in particular of the formula XXIIIa, are preferably used in the LC medium according to the invention in an amount of from 0.5% to 5% by weight, particularly preferably from 0.5% to 2% by weight.

The LC medium may additionally comprise one or more compounds of formula XXIV:

Wherein R ⁰、X⁰ and L ^1-6 have the meanings indicated in formula III, s represents 0 or 1, and

Representation of

In formula XXIV, X ⁰ may also represent an alkyl group having 1 to 6C atoms or an alkoxy group having 1 to 6C atoms. The alkyl or alkoxy group is preferably linear.

R ⁰ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F;

the compound having formula XXIV is preferably selected from the following subformulae:

Wherein R ⁰、X⁰ and L ¹ have the meanings indicated in formula III. R ⁰ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F, and L ¹ preferably is F;

Preferably is

R ⁰ is a straight chain alkyl or alkenyl group having 2 to 6C atoms;

the LC medium may further comprise one or more compounds having the formula:

Wherein R ¹ and X ⁰ have the meanings indicated for R ⁰ and X ⁰, respectively, in formula II. R ¹ preferably represents an alkyl group having 1 to 6C atoms. X ⁰ preferably represents F or Cl. In formula XXIV, X ⁰ very particularly preferably represents Cl.

The LC medium may further optionally comprise one or more compounds having the formula:

Wherein R ¹ and X ⁰ have the meanings indicated for R ⁰ and X ⁰, respectively, in formula II. R ¹ preferably represents an alkyl group having 1 to 6C atoms. X0 preferably represents F. LC media according to the invention particularly preferably comprise one or more compounds of formula XXIX, wherein X0 preferably represents F.

One or more compounds of the formulae XXVI to XXIX are preferably used in LC media according to the invention in amounts of 1% to 20% by weight, particularly preferably 1% to 15% by weight. Particularly preferred LC media comprise at least one compound of 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 radical, in particular ethyl, n-propyl, n-butyl or n-pentyl radical and very particularly preferably n-propyl.

One or more compounds of the formula XXIXa are preferably used in the LC medium according to the invention in an amount of from 1% to 15% by weight, particularly preferably from 2% to 10% by weight.

The LC medium may further comprise one or more of the following pyrimidine or pyridine compounds having the formula:

Wherein R ¹ and X ⁰ have the meanings indicated for R ⁰ and X ⁰, respectively, in formula II. R ¹ preferably represents an alkyl group having 1 to 6C atoms. X0 preferably represents F. The medium according to the invention may optionally comprise, in particular, one or more compounds of the formula XXX-1, wherein X0 preferably represents F. One or more compounds of the formulae XXX-1 to XXX-3 can be used in the LC medium according to the invention, preferably 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, LP and/or LP2 and optionally II and/or III, one or more compounds selected from the following formulae:

wherein the method comprises the steps of

"Alkyl" and "alkyl" are independently of each other C _1-6 -alkyl and preferably denote ethyl, propyl, butyl or pentyl, very preferably ethyl, propyl or butyl

"Alkenyl" and "alkenyl" preferably represent C _2-6 -alkenyl. Very preferred are compounds having the formulae Z1 and Z2.

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

in another preferred embodiment, the LC medium contains one or more compounds having the formula Z1 or a preferred subformula thereof and/or one or more compounds selected from the formulae Z2, Z3, Z4 and Z5 or a preferred subformula thereof.

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

Preferably, the medium contains 1,2 or 3 compounds selected from the formulae Z1, Z2, Z3 and Z4 or sub-formulae thereof.

The LC medium may additionally comprise one or more compounds having the general formula:

wherein the method comprises the steps of

R ¹ and R ² each independently of one another represent C _1-6 -alkyl, C _1-6 -alkoxy or C _2-6 -alkenyl.

The compound having formula XII is preferably selected from the following subformulae:

Wherein "alkyl" and "alkyl" each independently represent methyl, butyl, pentyl or hexyl.

Particular preference is given to compounds of the formulae XIIa and XIIC. In formula XIIb, "alkyl" preferably denotes, independently of one another, n-C ₃H₇、n-C₄H₉ or n-C ₅H₁₁, in particular n-C ₃H₇. In formula XIIC, "alkyl" preferably means n-C ₃H₇ and "alkyl" is preferably CH ₃ or n-C ₃H₇.

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 meaning indicated in formula III, and R ¹ and R ² each independently of one another represent n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6C atoms, and preferably each independently of one another represent alkyl having 1 to 6C atoms; in the compounds of formula XIV, at least one of the substituents R ¹ and R ² preferably represents an alkenyl group having 2 to 6C atoms.

In a further preferred embodiment, the LC medium comprises one or more compounds having the following formula S:

Wherein each substituent has the following meaning:

R ¹ and R ² are each, independently of one another, H atom, alkyl or alkoxy having 1 to 12C atoms or alkenyl or alkenyloxy having 2 or 12C atoms, wherein one or more non-adjacent CH ₂ groups are optionally substituted by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms, or cycloalkyl or cycloalkoxy groups having 3 to 12C atoms, wherein one or more H atoms may be replaced by halogen atoms,

A ⁰、A¹、A² each independently of the other represents phenylene-1, 4-diyl, wherein, 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、CHF₂、CH₂F、CF₃、OCH₃、OCHF₂ or OCF ₃, cyclohexane-1, 4-diyl, wherein, in addition, one or two non-adjacent CH ₂ groups may be 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 of one another represent -CF₂O-、-OCF₂-、-CH₂O-、-OCH₂-、-CO-O-、-O-CO-、-C₂H₄-、-C₂F₄-、-CF₂CH₂-、-CH₂CF₂-、-CFHCFH-、-CFHCH₂-、-CH₂CFH-、-CF₂CFH-、-CFHCF₂-、-CH＝CH-、-CF＝CH-、-CH＝CF-、-CF＝CF-、-C≡C- or a single bond,

K and l each independently of one another represent 0,1,2 or 3.

Preference is given to 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、CHF₂、CH₂F、OCH₃、OCHF₂、CF₃ or OCF ₃. Particularly preferred are the following compounds wherein A ⁰ represents

Preferably

And very particularly preferably therein

A ⁰ represents

The presence of the compound of formula S results in an LC medium with particularly high bright-ness, low rotational viscosity, broad nematic phase, high birefringence and excellent thermal and UV stability.

Particularly preferred compounds of formula S are those selected from the following subformulae:

Wherein R ¹ and R ² have the meaning indicated in formula S, and L ¹ to L ⁶ independently represent H or F. Wherein R ¹ and R ² preferably represent optionally fluorinated alkyl or alkoxy groups having 1 to 12C atoms, optionally fluorinated alkenyl or alkynyl groups having 2 to 12C atoms, optionally fluorinated cycloalkyl groups having 3 to 12C atoms.

Particularly preferred are optionally fluorinated alkyl, alkenyl or alkynyl groups having 1 to 5C atoms. L ² in the formulae S-1-1 to S-1-6 preferably represents F. In the formulae S-1-4 to S-1-6, L ³ and L ⁴ preferably represent H. In the formulae S-1-4 to S-1-6, L ³ and L ⁴ preferably represent F.

In a particularly preferred embodiment, the compound having formula S is described by the following structure:

wherein the method comprises the steps of

R ¹ and R ² independently of one another represent straight-chain or branched alkyl or alkoxy having 1 to 7C atoms, or alkenyl, alkenyloxy, alkoxyalkyl having 1 to 7C atoms, or cycloalkyl or cycloalkoxy having 3 to 12C atoms, wherein one or more non-adjacent CH ₂ groups are optionally substituted by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms, wherein one or more H atoms may be replaced by halogen atoms; and

L ¹ and L ² independently of one another represent an H atom or F, preferably F.

The LC medium may further optionally comprise one or more compounds of formula XIV, wherein at least one of substituents R ¹ and R ² represents an alkenyl group having 2 to 6C atoms, preferably selected from those of the following subformulae:

wherein "alkyl" and "alkyl" have the meaning indicated above and each independently of the other preferably represents methyl, ethyl or propyl.

The compound having formula XIV is preferably selected from the following subformulae:

Very preferred are compounds having the formulae XIVd-1, XIVe-1, XIVe-2 and XIVe-3.

In yet further embodiments, the LC medium comprises one or more compounds having formula XVI:

Wherein R ¹ and R ² have the meaning indicated in formulae I and LP1, respectively, and preferably each independently of the other represent an alkyl group having 1 to 6C atoms. L represents H or F.

Particularly preferred compounds of formula XVI are those having the following subformulae:

wherein the method comprises the steps of

"Alkyl" and "alkyl" each independently of the others denote a straight-chain alkyl radical having 1 to 6C atoms, in particular ethyl, propyl or pentyl, and

"Alkenyl" and "alkenyl" each independently of one another denote a straight-chain alkenyl radical having 2 to 6C atoms, in particular CH ₂＝CHC₂H₄、CH₃CH＝CHC₂H₄、CH₂ =ch and CH ₃ ch=ch.

Particularly preferred for administration are compounds having formulas XVIb and XVIc. Very particular preference is given to compounds having the following subformulae:

very particular preference is given to compounds of the formula XVIc-2.

The LC medium may optionally comprise one or more compounds having the formula:

wherein the method comprises the steps of

R ¹ and R ² have the meanings indicated in formulae I and LP1, respectively, and preferably each independently of one another represent an alkyl group having 1 to 6C 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 having the formula:

Wherein L, R ¹ and R ² have the meanings indicated for Y ¹、R⁰ and R ², respectively, in formula LP 1. R ¹ and R ² preferably represent alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl groups, each having up to 6C atoms.

In some further embodiments, the medium comprises one or more compounds having the formula:

Wherein R ¹ and R ² have the meaning indicated in formulae I and LP1, respectively, and preferably each independently of the other represent an alkyl group having 1 to 6C atoms.

In a preferred embodiment according to the invention, the LC medium contains, in addition to the compounds of the formulae I, LP1 and/or LP2, II and/or III, one or more compounds selected from the formulae Y and B

R ¹、R² in formula I for one of the meanings given for R ¹¹ and R ¹²,

R ³ is one of the meanings given for R ¹,

Z^x、Z^y -CH₂CH₂-、-CH＝CH-、-CF₂O-、-OCF₂-、-CH₂O-、-OCH₂-、-CO-O-、-O-CO-、-C₂F₄-、-CF＝CF-、-CH＝CH-CH₂O-、 Or a single bond, preferably a single bond,

Z ^z -CH₂O-、-O-、-C₂H₄-、-OCH₂ -, or a single bond,

Y ¹ -CH₂ -, -O-or-S-,

L ^1-4 H, F or Cl, preferably H or F, very preferably F,

X, y 0, 1 or 2, wherein x+y.ltoreq.3,

Z 0 or 1,

Wherein in formula B the dibenzofuran or dibenzothiophene group may also be further substituted by methyl or methoxy, 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 having the formula I, LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of formulae Z1, Z2 and Z3, and one or more compounds selected from the group consisting of formulae Y and B.

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

In a second preferred embodiment according to the invention, the LC medium does not contain compounds having the formula Y or B.

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

In the compounds having the formula Y and its subformulae, preferably both substituents L1 and L2 represent F. In another preferred embodiment of the invention, in the compounds of formula Y and its subformulae, one of the substituents L1 and L2 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 L ¹、L²、R¹、R²、Z^x、Z^y, x and Y have the meanings given in formula Y or one of the preferred meanings given above in formula I,

A represents a group consisting of 1 and 2,

B represents 0 or 1, and the number of the groups is,

L ¹、L² represents F or Cl, preferably F, and

L ⁵ represents an H atom or CH ₃,

Representation of

Preferably, in the compounds of formulae Y1 and Y2, L ¹ and L ² both represent F or one of L ¹ and L ² represents F and the other represents Cl, or L ¹ and L ² both represent F or one of L ¹ and L ² represents F and the other represents Cl.

Preferably, the LC medium comprises one or more compounds having formula Y1 selected from the group consisting of the following subformulae:

wherein the method comprises the steps of

A represents a group consisting of 1 and 2,

"Alkyl" and "alkyl" each independently of the others denote a straight-chain alkyl radical having 1 to 6C atoms,

"Alkenyl" means a straight chain alkenyl group having 2 to 6C atoms, an

L ⁵ represents an H atom or CH ₃.

"Alkenyl" preferably means CH₂＝CH-、CH₂＝CHCH₂CH₂-、CH₃-CH＝CH-、CH₃-CH₂-CH＝CH-、CH₃-(CH₂)₂-CH＝CH-、CH₃-(CH₂)₃-CH＝CH- or CH ₃-CH＝CH-(CH₂)₂ -.

Very preferably, the LC medium contains one or more compounds having the formula Y1 selected from the group consisting of the formulae 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. L ⁵ preferably represents an H atom.

Further preferred, the LC medium comprises one or more compounds having formula Y2 selected from the group consisting of the following subformulae:

wherein the method comprises the steps of

"Alkyl" and "alkyl" each independently of the others denote a straight-chain alkyl radical having 1 to 6C atoms, and

"Alkenyl" means a straight chain alkenyl group having 2 to 6C atoms,

(O) represents an oxygen atom or a single bond, and

L ⁵ represents an H atom or CH ₃, preferably an H atom.

Very preferably, the LC medium contains one or more compounds having the formula Y2 selected from the group consisting of the formulae 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 compounds of the formulae Y1 and Y2 or sub-formulae thereof in the medium is preferably from 1 to 20%, very preferably from 2 to 15% by weight.

Preferably, the LC medium contains 1,2 or 3 compounds of the formulae Y1 and Y2 or sub-formulae thereof, very preferably selected from the formulae 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 having the following subformulae:

wherein L ¹、L²、R¹ and R ² have one of the meanings given in formula Y or one of the preferred meanings as given in formulae I, LP1 and LP 2.

Preferred compounds having the 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 6C atoms;

"alkenyl" and "alkenyl" each independently of the others represent a straight-chain alkenyl group having 2 to 6C 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 CH ₃-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 of the other preferably represent a straight-chain alkoxy group having 3,4 or 5C atoms.

Preferably, in the compounds having the formula Y3 and its subformulae, both L ¹ and L ² represent F. Further preferably, in the compound having formula Y3, one of the substituents L ¹ and L ² represents F and the other represents Cl.

The proportion of compounds of the formula Y3 or its subformulae 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 a subformula thereof, more preferably compounds of formula Y3-6, very preferably compounds of formula Y3-6A.

In yet another preferred embodiment of the invention, the LC medium contains one or more compounds of formula Y having the formula Y4:

wherein R ¹ and R ² each independently of one another have one of the meanings indicated above in the formula Y, and

Each independently of the other represent

Wherein L ⁵ represents F or Cl, preferably F, and L ⁶ represents F, cl, OCF ₃、CF₃、CH₃、CH₂ F or CHF ₂, preferably F, and preferably at least one of rings G, I and K is different from unsubstituted benzene.

Most preferred compounds having formula Y4 are selected from the group consisting of the following subformulae:

wherein the method comprises the steps of

R represents a linear alkyl or alkoxy group having 1 to 7C atoms,

R ^* represents a straight-chain alkenyl group having 2 to 7C atoms,

(O) represents an oxygen atom or a single bond, and

M represents an integer from 1 to 6.

R preferably represents CH ₂＝CH-、CH₂＝CHCH₂CH₂-、CH₃ -CH=CH-

CH₃-CH₂-CH＝CH-、CH₃-(CH₂)₂-CH＝CH-、CH₃-(CH₂)₃-CH＝CH- Or (b)

CH₃-CH＝CH-(CH₂)₂-。

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

The proportion of the compounds of the formula Y4 or its subformulae in the medium is preferably from 0 to 10% by weight, very preferably from 1 to 6% by weight.

Particularly preferred compounds are those having the following subformulae

Wherein the method comprises the steps of

"Alkyl" and "alkyl" each independently denote a straight-chain alkyl group having 1 to 6C atoms, in particular ethyl, propyl or pentyl.

The use of the following compounds is particularly advantageous:

In another preferred embodiment of the 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 above for R ¹ in formula Y, "alkyl" represents a straight-chain alkyl group having 1 to 6C atoms, L ^x represents H or F, d represents 0 or 1, and z and m each independently of one another represent an integer from 1 to 6.

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

Further preferred embodiments are indicated below:

the LC medium comprises one or more compounds of formula Y having the formula

Wherein R ¹、R²、L¹、L², X, X and Z ^x have the meanings given in formula Y, and wherein at least one of the rings X is cyclohexenylene.

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 having formula LY is preferably selected from the group consisting of the following subformulae:

wherein the method comprises the steps of

R ¹ has the meaning indicated in the above 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 linear alkyl radical having 1 to 6C atoms or a linear alkenyl radical having 2 to 6C atoms, in particular CH₃、C₂H₅、n-C₃H₇、n-C₄H₉、n-C₅H₁₁、CH₂＝CH-、CH₂＝CHCH₂CH₂-、CH₃-CH＝CH-、CH₃-CH₂-CH＝CH-、CH₃-(CH₂)₂-CH＝CH-、CH₃-(CH₂)₃-CH＝CH- or CH ₃-CH＝CH-(CH₂)₂ -.

Very preferred are compounds having the formula LY 4.

Preferably, the medium contains 1,2 or 3 compounds of formula LY, very preferably compounds of formula LY 4.

The proportion of the compounds of the formula LY or its subformulae in the medium is preferably from 1 to 10% by weight.

-The medium comprises one or more compounds having the formula Y represented by the following subformulae:

Wherein R ¹、R²、L¹、L², 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 having the formula AY is preferably selected from the group consisting of the following subformulae:

wherein the method comprises the steps of

R ¹ has the meaning indicated above,

"Alkyl" means a straight chain alkyl group having 1 to 6C atoms,

(O) represents an oxygen atom or a single bond, and

V represents an integer from 1 to 6.

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

In a preferred embodiment of the invention, the medium contains one or more compounds of formula B selected from the following subformulae:

Wherein L ¹、L²、R¹ and R ³ have the meanings given in formula B.

Preferred compounds of formula B1 are selected from the following subformulae:

wherein R ¹ and R ³ independently represent a linear alkyl group having 1 to 6C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms.

Very preferred are compounds of the formulae B1-1 and B1-2 in which both radicals (O) represent oxygen atoms and R ¹ and R ³ independently represent alkyl radicals of methyl, ethyl, propyl, butyl, pentyl or hexyl, which are preferably straight-chain. Very preferably, one "alkyl" is ethyl and the other "alkyl" is n-pentyl.

Particularly preferred are compounds of the formula B1-2.

Preferably, the compound of formula B1-1 is selected from the group of compounds of formulae B1-1-1 to B1-1-11, preferably of formula B1-1-6:

wherein the method comprises the steps of

"Alkenyl" and "alkenyl" each independently of the others denote a straight-chain alkenyl radical having 2 to 6C atoms,

"Alkoxy" and "alkoxy" each independently represent a straight chain alkoxy group having 1 to 6C atoms.

Preferably, the compound of formula B1-2 is selected from the group of compounds of formulae B1-2-1 to B1-2-10, preferably of formula B1-2-6:

wherein the method comprises the steps of

Optionally, the LC medium comprises one or more compounds having the formula B1-1A and/or B1-2A:

wherein the method comprises the steps of

(O) represents O or a single bond,

R ^IIIA represents an alkyl or alkenyl group having up to 7C atoms or a group Cy-C _mH_2m+1 -,

M and n are identical or different and are 0, 1,2, 3,4, 5 or 6, preferably 1,2 or 3, very preferably 1,

Cy represents a cycloaliphatic radical having 3, 4 or 5 ring atoms, optionally substituted by alkyl or alkenyl groups each having up to 3C atoms, or by halogen or CN, and preferably represents cyclopropyl, cyclobutyl or cyclopentyl.

The compounds of the formulae B1-1A and/or B1-2A may alternatively or additionally be contained in the medium, preferably in addition to the compounds of the formulae B1-1 and B1-2.

Preferred compounds of the formula B1-1A and/or B1-2A are also as follows:

Wherein alkoxy represents a linear alkoxy group having 1 to 6C atoms or alternatively- (CH ₂)_n F, wherein n is 2, 3,4, or 5, preferably C ₂H₄ F).

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

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

In a preferred embodiment of the invention, the LC medium may comprise one or more compounds of formula B2-2

Wherein the method comprises the steps of

R ¹、R³ identical or different represent H, alkyl or alkoxy having 1 to 6C atoms, wherein one or more CH ₂ groups of these radicals are optionally substituted independently of one another by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other, and wherein, in addition, one or more H atoms may be replaced by halogen.

The compound having the formula B2-2 is preferably selected from the group of compounds having the formulae B2-2-1 to B2-2-10:

Wherein R ³ represents an alkyl group having 1 to 6C-atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl or alternatively- (CH ₂)_n F, wherein n is 2,3, 4 or 5, preferably C ₂H₄ F.

Particularly preferred compounds of formula B2 are selected from the following subformulae:

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

Preferably, the LC medium contains 1,2 or 3 compounds of formula B2 or a subformula 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 a straight-chain alkyl group having 1 to 6C 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 6C atoms, very preferably methyl, ethyl, propyl, butyl, pentyl or hexyl, more preferably ethyl or propyl, most preferably propyl.

Most preferred are compounds having the formulae B3-1-1 and B3-2-2.

In a preferred embodiment, the LC medium contains one or more compounds of the 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 dibenzothiophene group is substituted with methyl or methoxy, preferably with methyl, preferably in the para position of the substituent F, very preferably in the para position of the substituent F (i.e. in the meta position of the terminal group R ² or X ¹).

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

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

Preferably, the total proportion of compounds of formulae Y and B or sub-formulae thereof in the LC medium is from 2 to 25% by weight, very preferably from 3 to 20%.

Further preferred embodiments are indicated below:

The LC medium does not contain compounds of formula Y, B, LY or AY.

The LC medium contains no compounds having 1, 4-phenylene groups which are substituted in the 2-and 3-positions by F or Cl.

Compounds of formula ST

In some preferred embodiments of the invention, the LC medium may further comprise one or more compounds having the general formula ST:

Wherein each substituent has the following meaning:

Representation of

X ²¹、X²² are each independently of one another ground representation-O-, -CH ₂-、-CHR²³ -or-N-R ²³ -,

R ²¹ and R ²² each independently of one another represent H atoms or alkyl or alkoxy groups having 1 to 12C atoms, alkenyl, alkynyl, alkenyloxy or alkoxyalkyl groups having 2 to 12C atoms, or cycloalkyl having 3 to 12C atoms, wherein one or more non-adjacent CH ₂ groups are optionally substituted by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms, or cycloalkyl or cycloalkoxy groups having 3 to 12C atoms, wherein one or more H atoms may be replaced by halogen atoms,

R ²³ represents an H atom, an alkyl group having 1 to 10C atoms or an alkoxy group, and R represents 0 or 1.

LC media comprising compounds having the following subformulae ST-1, ST-2 and ST-3 exhibit particularly high long-term thermal and UV stability:

Wherein each substituent has the following meaning:

Representation of

R ²¹ and R ²² each independently of one another represent H atoms or alkyl or alkoxy groups having 1 to 7C atoms, and

R represents 0 or 1.

In a particularly preferred embodiment, the compound having the general formula ST may be selected from the following specific structures:

In a further preferred embodiment, the LC medium according to the invention may comprise at least one further sterically hindered phenol, which is mentioned in table B below.

Compounds of formula H

The LC medium may optionally contain one or more compounds having formula H

Wherein the method comprises the steps of

R ¹¹ each independently of the other represents a H atom, F, alkyl having 1 to 20C atoms, wherein one-CH ₂ -group or a plurality of-CH ₂ -groups (if present) may be replaced by-O-or-C (=o) -, but two adjacent-CH ₂ -groups may not be replaced by-O-, and one or more-CH ₂ -groups (if present) may be replaced by-ch=ch-, or-c≡c-, and one H atom or H atoms may be replaced by F, OR ¹³、N(R¹³)(R¹⁴) or R ¹⁵,

R ¹² each independently of the other represents an H atom, an alkyl group having 1 to 20C atoms, one of the-CH ₂ -groups OR a plurality of the-CH ₂ -groups may be replaced by-O-OR-C (=O) -, but two adjacent-CH ₂ -groups may not be replaced by-O-hydrocarbon groups containing cycloalkyl OR alkylcycloalkyl units, and wherein one-CH ₂ -group OR 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 wherein one H atom OR more H atoms may be replaced by F, OR ¹³、N(R¹³)(R¹⁴) OR R ¹⁵, OR an aromatic OR heteroaromatic hydrocarbon radical, wherein one H atom OR more H atoms may be replaced by OR ¹³、N(R¹³)(R¹⁴) OR R ¹⁵,

R ¹³ and R ¹⁴ each independently of one another represent an alkyl or acyl radical having 1 to 10C atoms or an aromatic hydrocarbon or carboxylic acid radical having 6 to 12C atoms,

R ¹⁵ each independently of the other represents an alkyl radical having 1 to 10C atoms, one-CH ₂ -group or 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-,

R ¹⁶ is each, independently of one another, H atom, alkyl or alkoxy having 1 to 10C atoms, O-cycloalkyl having 3 to 12C atoms, O ^· or OH,

S ¹¹ and S ¹² each independently of one another represent alkylene having 1 to 20C atoms, one-CH ₂ -group or-CH ₂ -groups, if present, being replaced by-O-or-C (=o) -but two adjacent-CH ₂ -groups not being replaced by-O-, and one H atom or H atoms being replaced by F, OR ¹³、N(R¹³)(R¹⁴) or R ¹⁵, or represent a single bond,

Y ¹¹ to Y ¹⁴ each independently of one another represent methyl or ethyl,

X ¹¹ is a group represented by the formula C,

Z ¹¹ to Z ¹⁴ each independently of one another represent-O-, - (C=O) -, -O- (C=O) -, and- (C=O) -O-, -O- (C=O) -O-, -N-R ¹³)-、-N-R¹³ - (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, Z ¹³ and Z ¹⁴ do not both represent-O-, and if q represents 0, Z ¹² and Z ¹³ do not both represent-O-,

P represents either 1 or 2 and is preferably chosen,

Q represents either 0 or 1 and,

O represents (3-p),

N represents an integer from 1 to 10,

M represents an integer from 0 to 8, wherein

N is 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 invention, in the compounds having formula H,

Representation of

(Biphenyl-1, 1', 3' -tetrayl) or

(Benzene-1, 2,4, 5-tetrayl)

Representation of(Benzene-1, 3, 5-triyl) or

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

Ethane-1, 2-diyl, propane-1, 3-diyl, butane-1, 4-diyl, pentane-1, 5-diyl, hexane-1, 6-diyl, heptane-1, 7-diyl, octane-1, 8-diyl,

(1, 4-Phenylene group),

(1, 3-Phenylene group),

(1, 2-Phenylene) or

(Trans-1, 4-cyclohexylene) and/or

Wherein the method comprises the steps of

-Z ¹²-S¹¹-Z¹¹ -represents, independently of one another in each occurrence, -O-、S¹¹-O-、-O-S¹¹-O-、-(C＝O)-O-S¹¹-O-、-O-(C＝O)-S¹¹-O-、-O-(C＝O)-S¹¹-(C＝O)-O-、-O-S¹¹-(C＝O)-O-、-(C＝O)-O-S¹¹-C、-(C＝O)-O-S¹¹-O-(C＝O)- or- (N-R ¹³)-S¹¹-O-、-(N-R¹³-C(＝O)-S¹¹ - (c=o) -O or a single bond, preferably-O-, -S ¹¹-O-、-O-S¹¹-O-、-(C＝O)-O-S¹¹-O-、-O-(C＝O)-S¹¹ -O-or-O-S ¹¹ - (c=o) -O-, and/or

S ¹¹ preferably represents alkylene having 1 to 20C 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 application, in the compounds of formula H,

A group selected from the group of the following formulas:

in a further preferred embodiment of the application, in the compounds of formula H,

Represents a group selected from the group of the following formulas

In a still further preferred embodiment of the present invention, in the compounds of formula H, wherein p preferably represents 1,

Representation ofPreferably-O-S ¹¹-O-、-S¹¹ -O-or-O-S ¹¹ -, particularly preferably-O-S ¹¹ -O-or-S ¹¹ -O-.

In a further preferred embodiment of the invention, in the compounds of formula H, the radicals

Represents a group selected from the group of the following formulas

In a further preferred embodiment of the present invention, wherein p is 2, which may be the same or different from those described above, in the compounds of formula H,

Represents a group selected from the group of the following formulas

And

In a still further preferred embodiment of the invention, which may be the same as or different from those described above, in the compounds of formula H, the radicals

At each occurrence, independently of each other, represent

Preferably

Compounds having the general formulae H-1-1, H-1-2 and H-1-3 show to be particularly effective 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 the mixture upon UV exposure.

In particularly preferred embodiments, the one or more compounds having formula H may be selected from the group consisting of compounds having the following formulas H-2-1 through H-2-6:

wherein the method comprises the steps of

R ¹¹ each independently of the other represents an H atom, an alkyl group having 1 to 20C atoms, wherein one-CH ₂ -group or a plurality of-CH ₂ -groups (if present) may be replaced by-O-or-C (=o) -, but two adjacent-CH ₂ -groups may not be replaced by-O-, and one or more-CH ₂ -groups (if present) may be replaced by-ch=ch-, or-c≡c-, and one H atom or H atoms may be replaced by F, OR ¹³、N(R¹³)(R¹⁴) or R ¹⁵,

R ¹⁶ represents a H atom or O,

N represents an integer from 0 to 12, and

S ¹¹ and S ¹² each independently of one another represent alkylene having 1 to 20C atoms, wherein one-CH ₂ -group or-CH ₂ -groups (if present) can be replaced by-O-or-C (=o) -but two adjacent-CH ₂ -groups cannot be replaced by-O-, and wherein one H atom or H atoms can be replaced by F, OR ¹³、N(R¹³)(R¹⁴) 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 formula:

And

Further preferred LC media are selected from the following preferred embodiments, including any combination thereof:

combinations of a compound of formula I with a compound of formula LP1, Z1 to Z7 and II and/or III

Combinations of a compound of formula I with a compound of formula LP2, Z1 to Z7 and II and/or III

Combinations of compounds of formula I with compounds of formulae LP1, LP2, II and/or III and compounds of formulae Z1 and Z4

The LC medium comprises one or more compounds of formula I or subformulae thereof and LP1 and/or LP2, II and/or III and one or more compounds selected from the group consisting of formulas 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 subformulae thereof.

The LC medium comprises one or more compounds of formula I or subformulae thereof and LP1 and/or LP2, II and/or III and one or more compounds selected from the group consisting of formulae Z1, Z2, Z3, Z4, Z5, IV, VI, XII, XIV, XVI, XVIIa, XVIIb, XVIIc, XX, LP1-1, XXIII, XXIX, XXXI and S and subformulae thereof.

The LC medium comprises one or more compounds selected from the group consisting of formulae II-1, II-2 and II-3, very preferably from formulae II-1 and II-2. The individual concentration of each of these compounds is preferably from 2% to 15% by weight. The total concentration of these compounds is preferably from 5 to 25% by weight.

The LC medium comprises one or more compounds selected from the group consisting of formulae III-1, III-4, III-6, III-16, III-19 and III-20, very preferably from the group consisting of formulae III-1, III-6, III-16 and III-20. The individual concentration of each of these compounds is preferably from 2% to 15% by weight. The total concentration of these compounds is preferably from 5 to 30% by weight.

The LC medium comprises one or more compounds of formula IV, preferably selected from formula IVa or IVc, very preferably selected from formula IVa-1 or IVc-1, most preferably formula IVc-1. The individual concentration of each of these compounds is preferably from 2% to 15% by weight. The total concentration of these compounds is preferably from 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 from 1% to 20% by weight. The total concentration of these compounds is preferably from 5% to 20% by weight.

The LC medium comprises one or more compounds having the formula Z1, preferably selected from the formula Z1-1. The total concentration of these compounds is preferably from 1 to 60% by weight, more preferably from 5 to 50% by weight.

The LC medium comprises one or more compounds having the formula Z2, preferably selected from the formulae Z2-1 and Z2-2. The total concentration of these compounds is preferably from 2 to 35% by weight, very preferably from 3 to 25%.

The LC medium comprises from 5 to 20% by weight of a compound of formula Z3, preferably of formula Z3-1.

The LC medium comprises from 5 to 20% by weight of a compound of formula Z4, preferably of formula Z4-1.

The LC medium comprises from 10 to 65%, very preferably from 20 to 60% by weight of a compound of formula Z5.

The LC medium comprises one or more compounds of formula LP1-1, preferably of formula LP1-1a or LP2-1b, very preferably of formula LP1-1 a. The concentration of these compounds is preferably from 2% to 15% by weight.

The LC medium comprises from 1 to 15% by weight of a compound of formula LP2-1 b.

The LC medium comprises one or more compounds of formula XII, preferably formula XIIa or XIIb, very preferably formula XIIa, most preferably formula XIIa-1. The concentration of these compounds is preferably from 2% to 15% by weight.

The LC medium comprises from 1 to 15% by weight of a compound of formula XIIb.

The LC medium comprises one or more compounds of formula XIV, preferably formula XIVd, very preferably formula XIVd-1. The concentration of these compounds is preferably from 2% to 10% by weight.

The LC medium comprises one or more compounds of formula XVIb, preferably of formula XVIb-1, XVIb-2 and/or XVIb-3. The concentration of these compounds is preferably from 2% to 15% by weight.

The LC medium comprises one or more compounds of formula XVIc, preferably of formula XVIc-1, XVIc-2 and/or XVIc-3. The concentration of these compounds is preferably from 2% to 20% by weight.

The LC medium comprises one or more compounds selected from the group consisting of formulae XVIIa, XVIIb and XVIIc, very preferably a compound of formula XVIIa wherein L is H and a compound of formula XVIIb wherein L is F. The total concentration of these compounds is preferably from 0.5% to 5% by weight.

The LC medium comprises one or more compounds of formula XX, preferably formula XXa. The concentration of these compounds is preferably from 2% to 10% by weight.

The LC medium comprises one or more compounds of formula XXI, preferably formula XXIa. The concentration of these compounds is preferably from 2% to 10% by weight.

The LC medium comprises one or more compounds of formula XXIII, preferably formula XXIIIa. The concentration of these compounds is preferably from 0.5% to 5% by weight.

The LC medium comprises one or more compounds of formula XXIX, preferably formula XXIXa. The concentration of these compounds is preferably from 2% to 10% by weight.

The LC medium comprises one or more compounds of formula XXX. The concentration of these compounds is preferably from 2% to 10% by weight.

The LC medium comprises one or more compounds of formula XXXI. The concentration of these compounds is preferably from 2% to 10% by weight.

The LC medium comprises one or more compounds of formula S, preferably of formula S-1-4-1. The concentration of these compounds is preferably from 1% to 25% by weight.

The LC medium comprises one or more compounds of the formula I, preferably of the formula I-1 and LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of the formulae Z1, Z2 and Z3 or the subformulae thereof, one or more compounds selected from the group consisting of the formula XIV, one or more compounds selected from the group consisting of the formulae IV, VI, XX, XXIII and XXIX or the subformulae thereof, and one or more compounds selected from the group consisting of the formulae LP2-1, XVI, XVIIa, XVIIb, XVIIc, XXXI and S or the subformulae thereof.

The LC medium comprises one or more compounds of formula I (preferably formula I-1), LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of formulae Z1, Z2, Z3, Z4 and Z5 or sub-formulae thereof, one or more compounds selected from the group consisting of formula XIVd or sub-formulae thereof, one or more compounds selected from the group consisting of formulae IVc, VIb, XXa, XXIIIa and XXIXa or sub-formulae thereof, and one or more compounds selected from the group consisting of formulae LP1-1b, XVIb, XVIc, XVIIa, XVIIb, XVIIc, XXXI and S or sub-formulae thereof.

The LC medium comprises one or more compounds of formula I (preferably formula I-1), LP1 and/or LP2, II and/or III, one or more compounds selected from the group consisting of formulae Z1, Z2 and Z3 or sub-formulae thereof, one or more compounds of formula Y (preferably selected from the group consisting of formulae 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 formulae II, III, IV, VI, XX, XXIII and XXIX or sub-formulae thereof, and one or more compounds selected from the group consisting of formulae LP2-1, XVI, XVIIa, XVIIb, XVIIc, XXXI and S or sub-formulae thereof.

The LC medium comprises one or more compounds of formula I (preferably formula I-1), LP1 and/or LP2, one or more compounds selected from the group consisting of formulae Z1, Z2, Z3, Z4 and Z5 or sub-formulae thereof, one or more compounds of formula B (preferably selected from the group consisting of formulae B1, B2 and B3), one or more compounds of formula XIVd or sub-formulae thereof, one or more compounds selected from the group consisting of formulae II, III, IVc, VIb, XXa, XXIIIa and XXIXa or sub-formulae thereof, and one or more compounds selected from the group consisting of formulae LP1-1B, XVIb, XVIc, XVIIa, XVIIb, XVIIc, XXXI and S or sub-formulae thereof.

In addition to the compounds of the formulae I, LP and/or LP2, the LC medium contains further compounds, which are selected from the group of compounds of the formulae Z1, Z2, Z3, IV, LP1-1, XIV, XVI, XVIIa, XVIIb, XVIIc, XXI, XXIII, XXIX, XXX, XXXI and XXIV or sub-formulae thereof.

In addition to the compounds of the formulae I, LP and/or LP2, the LC medium contains further compounds, which are selected from the group of compounds of the formulae Z1, Z2, Z3, IV, LP2-1, XIV, XVI, XVIIa, XVIIb, XVIIc, XXI, XXIII, XXIX, XXX, XXXI and XXIV or sub-formulae thereof.

The proportion of the compounds of formula I or its subformulae in the LC medium is preferably from 1% to 30% by weight, very preferably from 2% to 25% by weight, most preferably from 2% to 20% by weight.

The proportion of the compounds of the formulae Z1, Z2, Z3, Z4 and Z5 or sub-formulae thereof in the LC medium is generally from 10 to 65%, very preferably from 20 to 60% by weight.

The proportion of the compounds of the formula Y or its subformulae in the LC medium is generally from 0 to 15% by weight, very preferably from 2 to 10% by weight.

The proportion of the compounds of the formula B or its subformulae in the LC medium is generally from 0 to 15% by weight, very preferably from 2 to 10% by weight.

The proportion of the compounds of the formulae II, III, IV to VIII, XVIII to XXIII and XXVII to XXX in the LC medium is generally from 30 to 60% by weight.

The proportion of the compounds of the formulae XIV and XV in the LC medium is generally 40% to 70% by weight.

The proportion of the compounds of the formulae XIV, XVIIa-c and XXXI-XXXIII in the LC medium is generally from 0.5 to 15% by weight.

The term "alkyl" or "alkyl" in the present application includes straight and branched chain 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" includes straight and branched alkenyl groups having 2 to 6 carbon atoms, in particular straight chain groups. Preferred alkenyl groups are C ₂-C₇ -1E-alkenyl, C ₄-C₆ -3E-alkenyl, in particular C ₂-C₆ -1E-alkenyl. Examples of particularly preferred 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 CH ₂＝CH、CH₃ ch=ch.

The term "fluoroalkyl" preferably includes straight-chain groups having a terminal fluorine, i.e., fluoromethyl, 2-fluoroethyl, 3-fluoropropyl, 4-fluorobutyl, 5-fluoropentyl, 6-fluorohexyl and 7-fluoroheptyl. However, other positions of fluorine are not excluded.

The term "oxaalkyl" or "alkoxy" preferably includes a linear group having the formula C _nH_2n+1-O-(CH₂)_m, wherein n and m each independently of the other 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. Further preferably, the alkoxy or oxaalkyl groups may also contain one or more further O atoms, such that the oxygen atoms are not directly connected to each other.

By appropriately selecting the meanings of R ⁰ and X ⁰ in formulas II and III, the addressing time, threshold voltage, steepness of the transfer characteristic line, and the like can be changed in a desired manner. For example, 1E-alkenyl, 3E-alkenyl, 2E-alkenyloxy, and the like generally result in shorter addressing times, improved nematic tendencies, and higher ratios between the elastic constants K ₃ (bending) and K ₁ (splay) as compared to alkyl and alkoxy groups. 4-alkenyl, 3-alkenyl, etc. typically result in lower threshold voltages and lower K ₃/K₁ values compared to alkyl and alkoxy groups. The LC medium according to the invention is characterized in particular by a high delta epsilon value and thus has a significantly faster response time than prior art LC media.

The optimum mixing ratio of the compounds having the above-mentioned formula is essentially dependent on the desired properties, the choice of the components of the above-mentioned formula and the choice of any further components which may be present.

Suitable mixing ratios within the ranges indicated above can be readily determined from case to case.

The total amount of compounds having the above mentioned formula in the LC medium according to the invention is not critical. Thus, the LC medium may contain one or more additional components for the purpose of optimizing various characteristics. However, the greater the effect observed on the desired improvement of the characteristics of the medium, the higher the total concentration of the compounds having the formula mentioned above.

In a particularly preferred embodiment, the LC medium according to the invention comprises compounds having the formulae IV to VIII (preferably IV and V), wherein X ⁰ represents F, OCF ₃、OCHF₂、OCH＝CF₂、OCF＝CF₂ or OCF ₂-CF₂ H. Advantageous synergism with compounds having the formulae I, LP1 and/or LP2, II and III results in particularly advantageous properties. In particular, LC media comprising compounds having formulae I, LP1 and/or LP2, II and III are characterized by their low threshold voltages.

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

The 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 formulae LP1 and/or LP2 and one or more compounds selected from the group consisting of formulae 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 present invention may optionally comprise one or more polymerizable compounds. The polymerisable compounds are preferably selected from the group consisting of formula M

R^a-B¹-(Z^b-B²)_m-R^b M

R ^a and R ^b P、P-Sp-、H、F、Cl、Br、I、-CN、-NO₂、-NCO、-NCS、-OCN、-SCN、SF₅ or a straight-chain or branched alkyl radical having 1 to 25C atoms, where, in addition, one or more non-adjacent CH ₂ groups can each be, independently of one another, represented by-C (R ⁰)＝C(R⁰⁰)-、-C≡C-、-N(R⁰⁰) -, -O-, -S-, -CO-O-, -O-CO-O-substitution, 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 B ¹ and/or B ² contain a saturated C atom, R ^a and/or R ^b may also represent a group spiro-connected to the saturated C atom,

Wherein at least one of the substituents R ^a and R ^b represents or contains a group P or P-Sp-,

A polymerizable group of P and a polymerizable group of P,

Sp is a spacer or a single bond,

B ¹ and B ² are aromatic, heteroaromatic, cycloaliphatic or heterocyclic radicals, preferably having from 4 to 25 ring atoms, which may also contain condensed rings, and which are unsubstituted or monosubstituted or polysubstituted by L,

Z^b-O-、-S-、-CO-、-CO-O-、-OCO-、-O-CO-O-、-OCH₂-、-CH₂O-、-SCH₂-、-CH₂S-、-CF₂O-、-OCF₂-、-CF₂S-、-SCF₂-、-(CH₂)_n1-、-CF₂CH₂-、-CH₂CF₂-、-(CF₂)_n1-、-CH＝CH-、-CF＝CF-、-C≡C-、-CH＝CH-COO-、-OCO-CH＝CH-、CR⁰R⁰⁰ Or a single bond,

R ⁰ and R ⁰⁰ each independently of one another represent H or alkyl having 1 to 12C atoms,

M represents 0,1, 2,3 or 4,

N1 represents 1,2, 3 or 4,

L P、P-Sp-、OH、CH₂OH、F、Cl、Br、I、-CN、-NO₂、-NCO、-NCS、-OCN、-SCN、-C(＝O)N(R^x)₂、-C(＝O)Y¹、-C(＝O)R^x、-N(R^x)₂、 Optionally substituted silyl, optionally substituted aryl having 6 to 20C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25C atoms, wherein, in addition, one or more H atoms may be replaced by F, cl, P or P-Sp-,

P and Sp have the meanings indicated in formula M above,

Y ¹ is a halogen atom, and is a halogen atom,

R ^x represents P, P-Sp-, H, halogen, straight, branched or cyclic alkyl having 1 to 25C atoms (wherein, in addition, one or more non-adjacent CH ₂ groups may be replaced by-O-, -S-, -CO-, -CO-O-, -O-CO-O-substitution, 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, P or P-Sp-, an optionally substituted aryl or aryloxy group having 6 to 40C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40C atoms.

Particularly preferred compounds of the formula M are those in which B ¹ and B ² each independently of one another represent 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, flavone, 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 groups may be replaced by O and/or S, 1, 4-cyclohexenylene, 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, decahydro-1, 6-diyl, or octanedione, wherein, for example, 2, 6-diyl may be substituted by O and/or by one or more than one of these groups, wherein, for example, 2, 6-diyl, 2 may be unsubstituted or more than one of these groups may be defined by methyl groups.

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

Very preferred compounds of formula M are selected from the following formulae:

P ¹、P²、P³ a polymerizable group, preferably selected from ethyleneoxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl and epoxy,

Sp ¹、Sp²、Sp³ a single bond or a spacer, wherein in addition, one or more of the substituents P ¹-Sp¹-、P¹-Sp² -and P ³-Sp³ -may represent R ^aa, provided that at least one of the substituents P ¹-Sp¹-、P²-Sp² and P ³-Sp³ -present is different from R ^aa, preferably- (CH ₂)_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 linear or branched alkyl group having 1 to 25C atoms, wherein, in addition, one or more non-adjacent CH ₂ groups may each be replaced independently of one another by-C (R ⁰)＝C(R⁰⁰)-、-C≡C-、-N(R⁰) -, -O-, -S-, -CO-O-, -O-CO-O-, 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, CN or P ¹-Sp¹ -, particularly preferably straight-chain or branched, optionally mono-or poly-fluorinated, alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy groups having 1 to 12C atoms, where alkenyl and alkynyl have at least two C atoms and the branched radical has at least three C atoms,

R ⁰、R⁰⁰ H or alkyl having 1 to 12C atoms,

R ^y and R ^z H、F、CH₃ or CF ₃,

X ¹、X²、X³ -CO-O-, -O-CO-or a single bond,

Z ^M1 -O-、-CO-、-C(R^yR^z) or-CF ₂CF₂ -,

Z ^M2、Z^M3 -CO-O-、-O-CO-、-CH₂O-、-OCH₂-、-CF₂O-、-OCF₂ -or- (CH ₂)_n) -where n is 2, 3 or 4,

L F, cl, CN or straight-chain or branched, optionally mono-or polyfluorinated, alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12C 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 having the formulae M2 and M13.

Further preferred are the three reactive compounds M15 to M31, in particular M17, M18, M19, M22, M23, M24, M25, M30 and M31.

In the compounds of the formulae M1 to M31, the radicals

Preferably is

Wherein L has, identically or differently on each occurrence, one of the meanings given above or below for formula M, and is preferably F、Cl、CN、NO₂、CH₃、C₂H₅、C(CH₃)₃、CH(CH₃)₂、CH₂CH(CH₃)C₂H₅、OCH₃、OC₂H₅、COCH₃、COC₂H₅、COOCH₃、COOC₂H₅、CF₃、OCF₃、OCHF₂、OC₂F₅ or P-Sp-, very preferably F, cl, CN, CH ₃、C₂H₅、OCH₃、COCH₃、OCF₃ or P-Sp, more preferably F, cl, CH ₃、OCH₃、COCH₃ or OCF ₃, in particular F or CH ₃.

Preferred compounds of the formulae M1 to M31 are those in which P ¹、P² and P ³ represent acrylate, methacrylate, oxetane or epoxy groups, very preferably acrylate or methacrylate groups.

Further preferred compounds of formulae M1 to M31 are those wherein Sp ¹、Sp² and Sp ³ are single bonds.

Further preferred compounds of formulae M1 to M31 are those wherein one of Sp1, sp2 and Sp3 is a single bond and the other of Sp1, sp2 and Sp3 is different from a single bond.

Further preferred compounds of the formulae M1 to M31 are those in which the groups Sp1, sp2 and Sp3 which are different from the single bond represent- (CH ₂)_s1 -X "-, wherein s1 is an integer from 1 to 6, preferably 2, 3,4 or 5, and X' is a linking group with a benzene ring and is-O-; -O-CO-, -CO-O-, -O-CO-O-, or a single bond.

Particular preference is given to LC media comprising one, two or three polymerizable compounds of the formula M, preferably selected from the formulae M1 to M31.

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

Preferably, the proportion of polymerizable compound (preferably selected from 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, like those selected from formula M and table H, resulted in favorable properties like fast response times. Such LC media are particularly suitable for PSA displays, where they exhibit low image retention, fast and complete polymerization, fast generation of low pretilt angles that are stable after UV exposure, high reliability, high VHR values after UV exposure, and high birefringence. By a suitable choice of polymerizable compounds, the absorption of the LC medium at longer UV wavelengths can be increased, so that such longer UV wavelengths can be used for polymerization, which is advantageous for the display manufacturing process.

The polymerizable groups P are those which are suitable for polymerization reactions, such as, for example, free-radical or ionic chain polymerization, polyaddition or polycondensation, or for polymer-like reactions, such as, for example, addition or condensation on the main polymer chain. Particularly preferred are groups for chain polymerization, in particular those containing a c=c double bond or-c≡c-triple bond, and groups suitable for ring-opening polymerization, such as for example oxetane or epoxy groups.

Preferred groups P are selected from the group consisting of: CH ₂＝CW¹-CO-O-、CH₂＝CW¹ -CO-, CH₂＝CW²-(O)_k3-、CW¹＝CH-CO-(O)_k3-、CW¹＝CH-CO-NH-、CH₂＝CW¹-CO-NH-、CH₃-CH＝CH-O-、(CH₂＝CH)₂CH-OCO-、(CH₂＝CH-CH₂)₂CH-OCO-、(CH₂＝CH)₂CH-O-、(CH₂＝CH-CH₂)₂N-、(CH₂＝CH-CH₂)₂N-CO-、HO-CW²W³-、HS-CW²W³-、HW²N-、HO-CW²W³-NH-、CH₂＝CW¹-CO-NH-、CH₂＝CH-(COO)_k1-Phe-(O)_k2-、CH₂＝CH-(CO)_k1-Phe-(O)_k2-、Phe-CH＝CH-、HOOC-、OCN- And W ⁴W⁵W⁶ Si-, wherein W ¹ represents H, F, cl, CN, CF ₃, phenyl or alkyl having 1 to 5C atoms, in particular H, F, cl or CH ₃,W² and W ³ each independently of the other represent H or alkyl having 1 to 5C atoms, in particular H, methyl, ethyl or n-propyl, W ⁴、W⁵ and W ⁶ each independently of the other represent Cl, oxaalkyl having 1 to 5C atoms or oxacarbonylalkyl, W ⁷ and W ⁸ each independently of the other represent H, cl or alkyl having 1 to 5C atoms, phe represents 1, 4-phenylene, which is optionally substituted by one or more substituents L as defined above for formula M other than P-Sp-, k ₁、k₂ and k ₃ each independently of the other represent 0 or 1, k ₃ preferably represent 1, and k ₄ represents an integer from 1 to 10.

Very preferred groups P are selected from the group consisting of: CH ₂＝CW¹-CO-O-、CH₂＝CW¹ -CO-, CH₂＝CW²-O-、CH＝CW²-、CW¹＝CH-CO-(O)_k3-、CW¹＝CH-CO-NH-、CH₂＝CW¹-CO-NH-、(CH₂＝CH)₂CH-OCO-、(CH₂＝CH-CH₂)₂CH-OCO-、(CH₂＝CH)₂CH-O-、(CH₂＝CH-CH₂)₂N-、(CH₂＝CH-CH₂)₂N-CO-、CH₂＝CW¹-CO-NH-、CH₂＝CH-(COO)_k1-Phe-(O)_k2-、CH₂＝CH-(CO)_k1-Phe-(O)_k2-、Phe-CH＝CH- And W ⁴W⁵W⁶ Si-, wherein W ¹ represents H, F, cl, CN, CF ₃, phenyl or alkyl having 1 to 5C atoms, in particular H, F, cl or CH ₃,W² and W ³ each independently of the other represent H or alkyl having 1 to 5C atoms, in particular H, methyl, ethyl or n-propyl, W ⁴、W⁵ and W ⁶ each independently of the other represent Cl, oxaalkyl having 1 to 5C atoms or oxacarbonylalkyl, W ⁷ and W ⁸ each independently of the other represent H, cl or alkyl having 1 to 5C atoms, phe represents 1, 4-phenylene, k ₁、k₂ and k ₃ each independently of the other represent 0 or 1, k ₃ preferably represent 1, and k ₄ represents an integer from 1 to 10.

Very particularly preferred groups P are selected from the group consisting of: CH ₂＝CW¹ -CO-O-, in particular CH ₂＝CH-CO-O-、CH₂＝C(CH₃) -CO-O-and CH ₂ =cf-CO-O-, in addition CH ₂＝CH-O-、(CH₂＝CH)₂CH-O-CO-、(CH₂＝CH)₂ CH-O-,

Further preferred polymerizable groups P are selected from the group consisting of: vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy, most preferably selected from the group consisting of acrylate and methacrylate.

If Sp is different from a single bond, it is preferably of the formula Sp "-X" such that the corresponding substituent P-Sp-corresponds to the formula P-Sp "-X" -, wherein

Sp "represents an alkylene group having 1 to 20, preferably 1 to 12C atoms, which is optionally monosubstituted or polysubstituted by F, cl, br, I or CN, and wherein, in addition, one or more non-adjacent CH ₂ groups may each, independently of one another, be replaced 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.ident.C-in such a way that the O and/or S atoms are not directly connected to one another,

X' represents -O-、-S-、-CO-、-CO-O-、-O-CO-、-O-CO-O-、-CO-N(R⁰)-、-N(R⁰)-CO-、-N(R⁰)-CO-N(R⁰⁰)-、-OCH₂-、-CH₂O-、-SCH₂-、-CH₂S-、-CF₂O-、-OCF₂-、-CF₂S-、-SCF₂-、-CF₂CH₂-、-CH₂CF₂-、-CF₂CF₂-、-CH＝N-、-N＝CH-、-N＝N-、-CH＝CR⁰-、-CY²＝CY³-、-C≡C-、-CH＝CH-CO-O-、-O-CO-CH＝CH- or a single bond,

R ⁰ and R ⁰⁰ each independently of one another represent H or alkyl having 1 to 20C atoms, and

Y ² and Y ³ each independently represent H, F, cl or CN.

X' is preferably-O-, -S-; -CO-, -COO-, -OCO-, -O-COO-, -CO-NR ⁰-、-NR⁰-CO-、-NR⁰-CO-NR⁰⁰ -, or a single bond.

Typical spacers Sp and-Sp "-X" -are, for example, ,-(CH₂)_p1-、-(CH₂CH₂O)_q1-CH₂CH₂-、-CH₂CH₂-S-CH₂CH₂-、-CH₂CH₂-NH-CH₂CH₂- or- (SiR ⁰R⁰⁰-O)_p1 -, where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R ⁰ and R ⁰⁰ have the meanings indicated above in 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 groups Sp' are in each case straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxy ethylene, methyleneoxy butylene, ethylenethio ethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethylene, propylene and butylene groups.

In order to produce PSA displays, the polymerisable compounds contained in the LC medium are polymerised or crosslinked (if one compound contains two or more polymerisable groups) by in situ polymerisation in the LC medium between the substrates of the LC display, optionally with the application of a voltage to the electrodes.

The structure of the PSA display according to the invention corresponds to the usual geometry of PSA displays, as described in the prior art cited at the outset. The geometry without protrusions is preferred, in particular, among others, those in which, furthermore, the electrode on the color filter side is unstructured and only the electrode on the TFT side has grooves. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006/0066793 A1.

The combination of the above-mentioned compounds of the preferred embodiments with the above-mentioned polymeric compounds gives a low threshold voltage, a low rotational viscosity and a very good low temperature stability in the LC medium according to the invention, while at the same time giving a constant high definition bright spot and a high VHR value.

The use of LC media containing polymerizable compounds allows for a fast build up of particularly low pretilt angles in PSA displays. In particular, LC media exhibit significantly reduced response times, particularly also gray scale response times, in PSA displays compared to prior art media.

LC media with a nematic LC phase, and preferably without a chiral liquid crystal phase, are generally 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 electro-optical displays, in particular displays of the above-mentioned type, which contain an LC medium according to the invention as described above and below, in particular TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, HB-FFS, XB-FFS, PS-FFS, positive VA (vertical alignment) or positive PS-VA displays.

The invention also relates to an electro-optic display, such as for example an STN or Matrix LC (MLC) display, having two plane-parallel outer plates which together with a 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 enables a significantly broader range of usable parameters. The achievable combination of clearing point, viscosity at low temperature, thermal and UV stability and high optical anisotropy is far superior to previous materials from the prior art.

In particular, the combination of a compound of formula I with a compound of formula LP1 and/or LP2 and optionally with a compound selected from formulae II-XXXIII or subformulae thereof results in LC media exhibiting a moderately positive dielectric anisotropy and at the same time an increased dielectric constant epsilon _⊥ perpendicular to the longitudinal axis of the LC molecule, while maintaining a low rotational viscosity and a low value of the ratio gamma ₁/K₁. This allows energy efficient LC displays, especially FFS, HB-FFS, XB-FFS and IPS modes, with high brightness and transmittance 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. Furthermore, the LC medium according to the invention is particularly suitable for use in FFS, HB-FFS, XB-FFS and IPS displays based on dielectrically positive liquid crystals.

According to the LC medium of the present invention, while maintaining a nematic phase as low as-20 ℃ and preferably as low as-30 ℃, particularly preferably as low as-40 ℃, and a clearing point of ≡75 ℃, preferably ≡80 ℃, simultaneously allowing a rotational viscosity gamma ₁ of +.120 mPas, particularly preferably +.100 mPas to be achieved, enabling excellent MLC displays with fast response times to be obtained. The rotational viscosity was measured at 20 ℃.

The dielectric anisotropy Δεof the LC medium according to the invention is preferably ∈1.5 or more, very preferably from +3 to +18, most preferably from +5 to +15, at 20℃and 1 kHz.

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

The rotational viscosity γ ₁ of the LC medium according to the invention is preferably +.120 mPas, more preferably +.110 mPas, very preferably +.90 mPas.

The ratio gamma ₁/K₁ of the LC medium according to the invention (where gamma ₁ is the rotational viscosity and K ₁ is the elastic constant of the splay deformation) is preferably ∈7mpa·s/pN, very preferably ∈6mpa·s/pN, most preferably ∈5.5mpa·s/pN.

The average spring constant ratio K _av of the LC medium according to the present invention is preferably at least 14.0pN, very preferably at least 15.0pN, most preferably at least 16.0pN. K _av can be calculated according to the following formula: k _av＝(K₁+K₂+K₃)/3≈(K₁+1/2*K₁+K₃)/3.

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

It goes without saying that by a suitable choice of the components of the LC medium according to the invention, it is also possible to achieve a higher clearing point at a higher threshold voltage (for example above 100 ℃) or a lower clearing point at a lower threshold voltage, while maintaining other advantageous properties. When the viscosity is correspondingly only slightly increased, LC media with a higher Δε and thus a low threshold value can likewise be obtained. The MLC displays according to the invention are preferably operated at a first Gooch and Tarry transmittance minimum [ c.h. Gooch and H.A.Tarry, electron.Lett ] [ electronic flash ]10,2-4,1974; gooch and H.A.Tarry, appl.Phys [ applied physics ], volume 8, 1575-1584,1975], wherein, in addition to particularly advantageous electro-optical properties, such as, for example, a high steepness of the characteristic line and a low angular dependence of the contrast (german patent 30 22 818), a lower dielectric anisotropy is sufficient at the same threshold voltage as in a similar display at the second minimum. This enables a significantly higher specific resistance value to be achieved at the first minimum value using the LC medium according to the present invention than in the case of LC media comprising cyano compounds. By appropriate selection of the individual components and their proportions by weight, the person skilled in the art is able to set the desired birefringence of the pre-specified layer thickness of the MLC display using simple conventional methods.

Measurement of Voltage Holding Rate (HR) [ S.Matsumoto et al, liquid Crystals [ Liquid Crystals ]5,1320 (1989); niwa et al, proc.SID Conference, san Francisco, month 6, 1984, page 304 (1984); weber et al, liquid Crystals [ Liquid Crystals ]5,1381 (1989) ] have shown and include compounds of the formulaOr cyanophenyl cyclohexane of the formulaThe LC medium according to the invention comprising compounds having the formulae ST-1, ST-2, RV, IA and IB shows significantly less HR decrease on UV exposure than the ester-like LC medium.

The light stability and UV stability of the LC media according to the invention are significantly better, i.e. they show significantly less HR decrease when exposed to light, heat or UV.

The construction of the MLC display according to the invention, which consists of polarizers, electrode substrates and surface-treated electrodes, corresponds to the usual design of displays of this type. The term general design is broadly depicted herein and also includes all derivatives and variants of MLC displays, including in particular matrix display elements based on poly-Si TFTs or MIMs.

However, a significant difference between the display according to the invention and the conventional displays based on twisted nematic cells up to now is the choice of LC parameters of the LC layer.

LC media which can be used according to the invention are prepared in a manner customary per se, for example by mixing one or more compounds according to claim 1 with one or more compounds of the formulae II-XXXIIII or with further LC compounds and/or additives. In general, the desired amount of the component used in a smaller amount is dissolved in the component constituting the main component, advantageously at a high temperature. It is also possible to mix solutions of the components in organic solvents such as acetone, chloroform or methanol and to remove the solvent again after thorough mixing, for example by distillation.

The LC medium may also contain further additives known to the person skilled in the art and described in the literature, such as, for example, polymerization initiators, inhibitors, surface-active substances, light stabilizers, antioxidants (e.g. BHT, TEMPOL), microparticles, radical scavengers, nanoparticles, etc. For example, 0% to 15% of polychromatic dye or chiral dopant or initiator like651 Or 651907. Suitable stabilizers and dopants are mentioned in tables F and G below. In a preferred embodiment, the LC medium comprises one or more stabilizers selected from table G. Preferably, the proportion of stabilizers (like those of formulae ST and H as described above or listed in table G) in the LC medium is from 10 to 2000ppm, very preferably from 30 to 1000ppm.

Furthermore, polychromatic dyes, for example 0 to 15% by weight, may be added to the LC medium, in addition to nanoparticles, conductive salts, preferably complex salts of ethyldimethyldodecylammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylborate or crown ethers (see, for example, haller et al mol. Cryst. Liq. Cryst. [ molecular crystals and liquid crystals ]24,249-258 (1973)), substances for improving the conductivity, or for changing the dielectric anisotropy, viscosity and/or alignment of the nematic phase. Substances of this type are described, for example, in DE-A22 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 examples below, the structure of LC compounds is indicated by acronyms, the conversion to chemical formula is performed according to tables a to C below. All substituents C _mH_2m+1、C_nH_2n+1 and C _lH_2l+1 or C _mH_2m-1、C_nH_2n-1 and C _lH_2l-1 are straight-chain alkyl or alkylene radicals having in each case n, m and l C atoms, respectively. Preferably, n, m and l are each independently 1,2,3, 4, 5, 6 or 7. Table a shows the codes of the ring elements of the cores of the compounds, table B lists the bridging units, and table C lists the meanings of the symbols of the left-hand and right-hand end groups of the molecules. The acronym consists of: the code of the ring element with optional linking groups is followed by the code of the first hyphen and the left-hand end group, and the code of the second hyphen and the right-hand end group. Table D shows the illustrative structures of the compounds and their respective abbreviations.

Table a: ring element

Table B: bridging unit

Table C: end group

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

The following abbreviations are used:

( n, m, k and l are each independently of the other integers, preferably from 1 to 9, preferably from 1 to 7,k and l possibly also from 0 and preferably from 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 components of the LC medium are shown in tables D and E.

Table D

Table E

In the following formulae, n and m each independently of one another represent 0,1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, in particular 2, 3, 5, furthermore 0, 4, 6.

Particularly preferred for administration are LC media comprising at least one, two, three, four or more compounds from table E in addition to compounds having formulae I, LP and/or LP 2.

Table F

Table F indicates possible dopants that are typically added to LC media according to the present invention. The LC medium preferably contains 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, stabilizers are mentioned, which may be additionally added to the LC medium according to the invention, for example in an amount of 0 to 10% by weight.

Q=1, 2, 3, 4, 5, 6, 7, 8, 9 or 10

Table H

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

In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from polymerizable compounds having the formulae RM-1 to RM-182. Of these, 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-109、RM-116、RM-117、RM-120、RM-121、RM-122、RM-139、RM-140、RM-142、RM-143、RM-145、RM-146、RM-147、RM-149、RM-156 to RM-163, RM-169, RM-170, and RM-171 to RM-183 are particularly preferable.

TABLE I

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

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

The following examples are intended to illustrate the invention without limiting it.

In the above and below, the percentage data represent weight percentages. All temperatures are expressed in degrees celsius. m.p. represents melting point, cl.p. =clearing point. In addition, c=crystalline, n=nematic, s=smectic phase and i=isotropic phase. The data between these symbols represents the transition temperature. In addition, the following notations are used

V ₀ Freedericks threshold voltage at 20 c, capacitive V,

V ₁₀ for a 10% transmittance voltage V,

N _e is the extraordinary refractive index measured at 20℃and 589nm,

N ₀ the ordinary refractive index measured at 20℃and 589nm,

Optical anisotropy measured at 20℃and 589nm,

Epsilon _⊥ dielectric polarizability (or "dielectric constant") perpendicular to the longitudinal axis of the molecule at 20 c and 1kHz,

Epsilon _|| dielectric polarizability (or "dielectric constant") parallel to the longitudinal axis of the molecule at 20 c and 1kHz,

Dielectric anisotropy of delta epsilon at 20 ℃ and 1kHz,

Cl.p. or

T (N, I) is the clearing point [ DEGC ],

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

A rotational viscosity [ mPa.s ] measured at 20℃of gamma ₁,

K ₁ spring constant, "splay" deformation [ pN ] at 20 ℃,

K ₂ spring constant, "twist" deformation [ pN ] at 20 ℃,

K ₃ spring constant, "bending" deformation at 20 [ pN ], and

VHR voltage holding ratio.

All physical properties were determined according to "Merck Liquid Crystals, physical Properties of Liquid Crystals [ merck liquid crystal, physical properties of liquid crystal ]", state 1997, 11 month, merck group (MERCK KGAA), germany, and applicable to temperatures of 20 ℃ unless explicitly indicated otherwise.

Detailed Description

Examples

Example M1 (comparative)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 13.50pN and a gamma ₁/K₁ of 3.29 mPas/pN.

Mixture example S1 (stabilization with Compounds of formula ST-1-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M1	99.95wt.-％
		Compounds of formula ST-1-3	500ppm

The addition of 500ppm of the compound of formula ST-1-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M1, without affecting the remaining physical properties of the mixture M1.

EXAMPLE M2 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 14.23pN and a gamma ₁/K₁ of 3.28 mPas/pN. Thus, the LC mixture of example 2 (invention) has a significantly higher average elastic constant K _av compared to the LC mixture of example 1 (comparative), whereas the response time parameter γ ₁/K₁ of both mixtures is substantially the same.

Mixture example S2 (stabilization with Compounds of formula H-3-1)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M2	99.9wt.-％
		Compounds of formula H-3-1	1 000ppm

The addition of 1 ppm of the compound of formula H-3-1 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M2, without affecting the remaining physical properties of the mixture M2.

EXAMPLE M3 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 14.87pN and a gamma ₁/K₁ of 3.19 mPas/pN.

Mixture example S3 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M3	99.95wt.-％
		Compounds of formula ST-2-3	500ppm

The addition of 500ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M3, without affecting the remaining physical properties of the mixture M3.

EXAMPLE M4 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 14.85pN and a gamma ₁/K₁ of 3.09 mPas/pN.

Mixture example S4 (stabilization with Compounds having the formula H-3-3)

The nematic LC mixture according to the invention is formulated as follows:

mixture M4	99.9wt.-％
		Compounds having the formula H-3-3	1 000ppm

The addition of 1 ppm of the compound of formula H-3-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M4, without affecting the remaining physical properties of the mixture M4.

EXAMPLE M5 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 14.77pN and a gamma ₁/K₁ of 3.33 mPas/pN.

Mixture example S5 (stabilization with Compounds of formula H-3-5)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M5	99.995wt.-％
		Compounds of formula H-3-5	50ppm

The addition of 50ppm of the compound of formula H-3-5 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M5, without affecting the remaining physical properties of the mixture M5.

EXAMPLE M6 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 14.75pN and a gamma ₁/K₁ of 3.35 mPas/pN.

Mixture example S6 (stabilization with Compounds of formula ST-1-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M6	99.95wt.-％
		Compounds of formula ST-1-3	500ppm

The addition of 500ppm of the compound of formula ST-1-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M6, without affecting the remaining physical properties of the mixture M6.

EXAMPLE M7 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 16.23pN and a gamma ₁/K₁ of 3.17 mPas/pN.

Mixture example S7 (stabilization with Compounds of formula ST-1-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M6	99.97wt.-％
		Compounds of formula ST-1-3	300ppm

The addition of 300ppm of the compound of formula ST-1-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M7, without affecting the remaining physical properties of the mixture M7.

EXAMPLE M8 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 15.73pN and a gamma ₁/K₁ of 3.20 mPas/pN.

Mixture example S8 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

mixture M8	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 500ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M8, without affecting the remaining physical properties of the mixture M8.

EXAMPLE M9 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 18.75pN and a gamma ₁/K₁ of 3.08 mPas/pN.

Mixture example S9 (stabilization with Compounds having the formula H-3-1)

The nematic LC mixture according to the invention is formulated as follows:

The addition of 1 ppm of the compound of formula H-3-1 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M9, without affecting the remaining physical properties of the mixture M9.

Example M10 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 16.22pN and a gamma ₁/K₁ of 5.57 mPas/pN.

Mixture example S10 (stabilization with Compounds of formula H-3-1)

The nematic LC mixture according to the invention is formulated as follows:

The addition of 1 ppm of the compound of formula H-3-1 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M10, without affecting the remaining physical properties of the mixture M10.

Example M10 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 16.00pN and a gamma ₁/K₁ of 5.49 mPas/pN.

Mixture example S11 (stabilization with Compounds of formula H-3-1)

The nematic LC mixture according to the invention is formulated as follows:

The addition of 1 ppm of the compound of formula H-3-1 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M11, without affecting the remaining physical properties of the mixture M11.

EXAMPLE M11 (invention)

Nematic LC media were formulated as follows:

The LC mixture had K _av of 16.52pN and gamma ₁/K₁ of 5.72 mPas/pN.

Mixture example S11 (stabilization with Compounds of formula ST-1-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M11	99.95wt.-％
		Compounds of formula ST-1-3	500ppm

The addition of 500ppm of the compound of formula ST-1-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M11, without affecting the remaining physical properties of the mixture M11.

Example M12 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 15.83pN and a gamma ₁/K₁ of 5.39 mPas/pN.

Mixture example S12 (stabilization with Compounds of formula ST-1-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M11	99.96wt.-％
		Compounds of formula ST-1-3	400ppm

The addition of 400ppm of the compound of formula ST-1-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M12, without affecting the remaining physical properties of the mixture M12.

EXAMPLE M13 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 15.08pN and a gamma ₁/K₁ of 3.08 mPas/pN.

Mixture example S13 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M13	99.95wt.-％
		Compounds of formula ST-2-3	500ppm

The addition of 500ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M13, without affecting the remaining physical properties of the mixture M13.

Example M14 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 15.20pN and a gamma ₁/K₁ of 3.25 mPas/pN.

Mixture example S14 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M14	99.97wt.-％
		Compounds of formula ST-2-3	300ppm

The addition of 300ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M14, without affecting the remaining physical properties of the mixture M14.

EXAMPLE M15 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 14.57pN and a gamma ₁/K₁ of 3.26 mPas/pN.

Mixture example S15 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

mixture M15	99.97wt.-％
		Compounds of formula ST-2-3	300ppm

The addition of 300ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M15, without affecting the remaining physical properties of the mixture M15.

EXAMPLE M16 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 15.85pN and a gamma ₁/K₁ of 3.23 mPas/pN.

Mixture example S16 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M16	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 400ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M16, without affecting the remaining physical properties of the mixture M16.

EXAMPLE M17 (invention)

Nematic LC media were formulated as follows:

the LC mixture had a K _av of 17.65pN and a gamma ₁/K₁ of 3.20 mPas/pN.

Mixture example S17 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M17	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 400ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M17, without affecting the remaining physical properties of the mixture M17.

Example M18 (invention)

Nematic LC media were formulated as follows:

Mixture example S18 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

mixture M18	99.97wt.-％
		Compounds of formula ST-2-3	300ppm

The addition of 300ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M18, without affecting the remaining physical properties of the mixture M18.

Example M19 (invention)

Nematic LC media were formulated as follows:

Mixture example S19 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M19	99.97wt.-％
		Compounds of formula ST-2-3	300ppm

The addition of 300ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M19, without affecting the remaining physical properties of the mixture M19.

EXAMPLE M20 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 13.52pN and a gamma ₁/K₁ of 3.63 mPas/pN.

Mixture example S20 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M20	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 400ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M20, without affecting the remaining physical properties of the mixture M20.

Example M21 (invention)

Nematic LC media were formulated as follows:

the LC mixture had a K _av of 13.80pN and a gamma ₁/K₁ of 3.51 mPas/pN.

Mixture example S21 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M21	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 400ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M21, without affecting the remaining physical properties of the mixture M21.

EXAMPLE M22 (invention)

Nematic LC media were formulated as follows:

The LC mixture had a K _av of 13.85pN and a gamma ₁/K₁ of 3.43 mPas/pN.

Mixture example S22 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M22	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 400ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M22, without affecting the remaining physical properties of the mixture M22.

EXAMPLE M23 (invention)

Nematic LC media were formulated as follows:

mixture example S23 (stabilization with Compounds of formula ST-2-3)

The nematic LC mixture according to the invention is formulated as follows:

Mixture M23	99.96wt.-％
		Compounds of formula ST-2-3	400ppm

The addition of 400ppm of the compound of formula ST-2-3 significantly improved VHR ₁₀₀ after UV exposure compared to the unstabilized mixture M23, without affecting the remaining physical properties of the mixture M23.

Claims

1. Liquid-crystalline medium, characterized in that it comprises one or more compounds of the formula I

R ¹¹ and R ¹² each independently of one another represent H atoms, alkyl or alkoxy groups having 1 to 12C atoms or alkenyl or alkenyloxy groups having 2 to 12C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms, or cycloalkyl or cycloalkoxy groups having 3 to 12C atoms, wherein one or more H atoms may be replaced by halogen atoms, preferably cyclopentyl or cyclopentyloxy;

R ⁰ is an alkyl or alkoxy group having 1 to 12C atoms or an alkenyl group having 2 to 12C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms;

R ² is alkyl or alkoxy having 1 to 6C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms;

X ² F atoms or alkyl or alkoxy groups having 1 to 6C atoms or alkenyl or alkenyloxy groups having 2 to 6C atoms, wherein one or more H atoms are replaced by F atoms;

y ⁰ H or CH ₃;

L ¹ and L ² are H, F or Cl independently of each other;

y ⁰ H or CH ₃;

m and n independently of one another represent 0, 1 or 2.

2. Liquid-crystalline medium according to claim 1, wherein the one or more compounds of formula I are selected from those of formulae I-1 to I-5:

wherein the method comprises the steps of

R ¹¹ and R ¹² each independently of one another represent H atoms, alkyl or alkoxy groups having 1 to 6C atoms or alkenyl or alkenyloxy groups having 2 or 6C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-, -O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other and wherein one or more H atoms may be replaced by halogen atoms, or cycloalkyl or cycloalkoxy groups having 3 to 6C atoms wherein one or more H atoms may be replaced by halogen atoms.

3. The liquid-crystalline medium according to claim 1 or 2, characterized in that the one or more compounds of the formulae LP1 and LP2 are described by the formulae LP1-1 and LP 2-1:

wherein the method comprises the steps of

R ⁰ is an alkyl or alkoxy group having 1 to 6C atoms or an alkenyl group having 2 to 12C atoms, wherein one or more CH ₂ groups are optionally replaced by-C.ident.C-, -CF ₂O-、-OCF₂ -, -ch=ch-,-O-, -CO-O-or-O-CO-substitution in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen atoms;

x ² F atoms or alkyl or alkoxy groups having 1 to 3C atoms or alkenyl or alkenyloxy groups having 2 or 3C atoms, wherein one or more H atoms are replaced by F atoms; and

Y ⁰ H or CH ₃.

4. A liquid-crystalline medium according to one or more of claims 1 to 3, characterized in that it comprises one or more compounds selected from the group consisting of the following formulae II and III:

R ⁰ one of the meanings given for R ¹¹ in claim 1;

L ^1-6 independently of one another H or F;

X ⁰, independently of one another, F, cl, haloalkyl, haloalkenyl, haloalkoxy or haloalkenoxy having up to 6C atoms; and

Y ⁰ H or CH ₃.

5. The liquid-crystalline medium according to claim 4, wherein the one or more compounds of formula II are selected from the following subformulae:

Wherein R ⁰ and X ⁰ have the meanings given in formula II.

6. The liquid-crystalline medium according to claim 4, wherein the one or more compounds of formula III are selected from the following subformulae:

wherein R ⁰ and X ⁰ have the meanings given in formula III.

7. Liquid-crystalline medium according to one or more of claims 1 to 6, characterized in that it comprises one or more compounds selected from the following formulae Z1 to Z7:

Wherein "alkyl" and "alkyl" represent C _1-6 -alkyl, and

"Alkenyl" and "alkenyl" refer to C _2-6 -alkenyl.

8. Liquid-crystalline medium according to one or more of claims 1 to 7, characterized in that it comprises one or more compounds selected from the group consisting of the following formulae:

Wherein R ¹ and R ² each independently of one another represent n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6C atoms,

"Alkenyl" means C _2-6 -alkenyl, and

L ¹ has the meaning indicated in claim 1.

9. Liquid-crystalline medium according to one or more of claims 1 to 8, characterized in that it additionally comprises one or more compounds selected from the group consisting of the following formulae:

Wherein R ⁰、X⁰、L¹、L² and Y ⁰ have the meanings indicated in claim 4, L ³ and L ⁴ independently of one another have one of the meanings given for L ¹; and

Z ⁰ represents -C₂H₄-、-(CH₂)₄-、-CH＝CH-、-CF＝CF-、-C₂F₄-、-CH₂CF₂-、-CF₂CH₂-、-CH₂O-、-OCH₂-、-COO- or-OCF ₂ -, in which case a single bond is also represented in formulae V and VI and-CF ₂ O-is also represented in formulae V and VIII; and

S represents 0 or 1.

10. Liquid-crystalline medium according to one or more of claims 1 to 9, characterized in that it comprises one or more compounds selected from the group consisting of the following formulae:

Wherein R ⁰、L^1-4、Y⁰ and X ⁰ each independently of one another have one of the meanings indicated in claim 4.

11. Liquid-crystalline medium according to one or more of claims 1 to 10, characterized in that it comprises one or more compounds selected from the group consisting of the following formulae:

Wherein R ¹ and X ⁰ have the meaning of R ⁰ and X ⁰ indicated in claim 4.

12. Liquid-crystalline medium according to one or more of claims 1 to 11, characterized in that it comprises one or more compounds of the formulae I, LP and LP2 and one or more compounds selected from the group consisting of the formulae Z1, Z2, Z3, Z4, Z5, II, III, IV, VI, XIV, XX, XXIII, XXIX, XVI, XVIIa, XVIIb and XVIIc.

13. Liquid-crystalline medium according to one or more of claims 1 to 12, characterized in that it additionally comprises one or more polymerizable compounds.

14. Process for preparing a liquid-crystalline medium according to one or more of claims 1 to 13, characterized in that one or more compounds of the formula I and one or more compounds of the formula LP1 and/or LP2 are mixed with one or more mesogenic compounds and optionally one or more polymerizable compounds and/or one or more additives.

15. Use of a liquid-crystalline medium according to one or more of claims 1 to 13 for electro-optical purposes.

16. An electro-optic liquid-crystal display comprising a liquid-crystalline medium according to one or more of claims 1 to 13.

17. The electro-optic liquid crystal display of claim 15 which is 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-FS, polymer stabilized SA-HB-FFS, polymer stabilized SA-XB-FFS, positive VA or positive PS-VA display.

18. An electro-optic liquid crystal display according to claim 16 which is an FFS, HB-FFS, XB-FFS, PS-HB-FFS, PS-XB-FFS, IPS or PS-IPS display.