EP4680691A1 - Liquid-crystal medium - Google Patents

Liquid-crystal medium

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Publication number
EP4680691A1
EP4680691A1 EP24712182.5A EP24712182A EP4680691A1 EP 4680691 A1 EP4680691 A1 EP 4680691A1 EP 24712182 A EP24712182 A EP 24712182A EP 4680691 A1 EP4680691 A1 EP 4680691A1
Authority
EP
European Patent Office
Prior art keywords
compounds
atoms
mixture
formula
another
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP24712182.5A
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German (de)
French (fr)
Inventor
Sven Christian Laut
Hee-Kyu Lee
Minghui Yang
Jing Wang
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Merck Patent GmbH
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Merck Patent GmbH
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Publication of EP4680691A1 publication Critical patent/EP4680691A1/en
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/34—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring
    • C09K19/3441—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having nitrogen as hetero atom
    • C09K19/3444—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having nitrogen as hetero atom the heterocyclic ring being a six-membered aromatic ring containing one nitrogen atom, e.g. pyridine
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/42—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/062—Non-steroidal liquid crystal compounds containing one non-condensed benzene ring
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
    • C09K19/3098—Unsaturated non-aromatic rings, e.g. cyclohexene rings
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/34—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring
    • C09K19/3491—Non-steroidal liquid crystal compounds containing at least one heterocyclic ring having sulfur as hetero atom
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K2019/0444—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group
    • C09K2019/0448—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit characterized by a linking chain between rings or ring systems, a bridging chain between extensive mesogenic moieties or an end chain group the end chain group being a polymerizable end group, e.g. -Sp-P or acrylate
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
    • C09K19/12—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings at least two benzene rings directly linked, e.g. biphenyls
    • C09K2019/121—Compounds containing phenylene-1,4-diyl (-Ph-)
    • C09K2019/122—Ph-Ph
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/10—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings
    • C09K19/12—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing at least two benzene rings at least two benzene rings directly linked, e.g. biphenyls
    • C09K2019/121—Compounds containing phenylene-1,4-diyl (-Ph-)
    • C09K2019/123—Ph-Ph-Ph
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
    • C09K19/3001—Cyclohexane rings
    • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
    • C09K2019/3004—Cy-Cy
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
    • C09K19/3001—Cyclohexane rings
    • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
    • C09K2019/301—Cy-Cy-Ph
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
    • C09K19/3001—Cyclohexane rings
    • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
    • C09K2019/3016—Cy-Ph-Ph
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/06—Non-steroidal liquid crystal compounds
    • C09K19/08—Non-steroidal liquid crystal compounds containing at least two non-condensed rings
    • C09K19/30—Non-steroidal liquid crystal compounds containing at least two non-condensed rings containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
    • C09K19/3001—Cyclohexane rings
    • C09K19/3003—Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
    • C09K2019/3027—Compounds comprising 1,4-cyclohexylene and 2,3-difluoro-1,4-phenylene

Definitions

  • the present invention relates to a liquid-crystal (LC) medium based on a mixture of polar compounds, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the fringe-field switching mode, to an LC display of the fringe-field switching mode comprising the LC medium, especially an energy-saving LC display, to a process of preparing the LC medium, and to a process of manufacturing the LC display.
  • LCD liquid-crystal display
  • TN twisted nematic
  • TN LCDs have the disadvantage of a strong viewing-angle dependence of the contrast.
  • FFS far-field switching
  • FFS displays usually contain an LC medium with positive dielectric anisotropy, and an alignment layer, usually of polyimide, which provides planar alignment to the molecules of the LC medium.
  • FFS displays can be operated as active-matrix or passive-matrix displays.
  • active-matrix displays individual pixels are usually addressed by integrated, non-linear active elements, such as, for example, transistors (for example thin-film transistors (“TFTs”)), while in the case of passive-matrix displays, individual pixels are usually addressed by the multiplex method, as known from the prior art.
  • TFTs thin-film transistors
  • the displays further comprise an alignment layer, preferably of polyimide provided on at least one of the substrates that is in contact with the LC medium and induces planar alignment of the LC molecules of the LC medium.
  • These displays require an LC medium with high reliability.
  • so-called VA (“vertically aligned”) displays are known which have a broad viewing angle and fast response times.
  • the LC cell of a VA display contains a layer of an LC medium between two transparent electrodes, where the LC medium usually has a negative value of the dielectric anisotropy ( ⁇ ⁇ ). In the switched-off state, the molecules of the LC layer are aligned perpendicular to the electrode surfaces (homeotropically) or have a tilted homeotropic alignment.
  • IPS in-plane switching
  • VA in-plane switching
  • VA displays having tilt domains have, compared with conventional VA displays, a greater viewing-angle independence of the contrast and the grey shades.
  • displays of this type are simpler to produce since additional treatment of the electrode surface for uniform alignment of the molecules in the switched-on state, such as, for example, by rubbing, is no longer necessary.
  • the preferential direction of the tilt or pretilt angle is controlled by a special design of the electrodes.
  • the use of LC media with negative dielectric anisotropy in VA or FFS displays has also several drawbacks. For example, they have a significantly lower reliability compared to LC media with positive dielectric anisotropy.
  • the term "reliability” as used hereinafter means the quality of the performance of the display during time and with different stress loads, such as light load, temperature, humidity, or voltage which cause display defects such as image sticking (area and line image sticking), mura, yogore etc. and which are known to the skilled person in the field of LC displays.
  • VHR voltage holding ration
  • the reduced reliability of an LC medium with negative dielectric anisotropy in a VA or FFS display can be explained by an interaction of the LC molecules with the polyimide of the alignment layer, as a result of which ions are extracted from the polyimide alignment layer, and wherein LC molecules with negative dielectric anisotropy do more effectively extract such ions.
  • the LC medium has to show a high reliability and a high VHR value after UV exposure. Further requirements are a high specific resistance, a large working- temperature range, short response times even at low temperatures, a low threshold voltage, a multiplicity of grey levels, high contrast and a broad viewing angle, and reduced image sticking.
  • a further object of the invention is to provide FFS-, VA-, and IPS- displays with high contrast ratio, good transmission, high reliability, a VHR value especially after backlight exposure, a high specific resistance, a large working-temperature range, short response times even at low temperatures, a low threshold voltage, a multiplicity of grey levels, high contrast and a broad viewing angle, and reduced image sticking.
  • the contrast ratio is defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing, i.e., the transmittane (white level) to the scattering parameter (dark level).
  • the contrast ratio can be significantly improved by the lower scattering parameter (high Kavg). Therefore, a LC mixture having high Kavg is very effective to achieve a high contrast ratio display.
  • a further object of the present invention is to provide LC mixtures with a favourably high average elastic constant Kavg, which contributes to a high contrast ratio. It was found that one or more of these objects could be achieved by providing an LC medium as disclosed and claimed hereinafter.
  • the LC medium comprises one or more are compounds of formula I, wherein R 11 denotes straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms, R 12 denotes straight-chain alkoxy having 1 to 7 C atoms, A 1 denotes cyclohexane, Z 1 denotes a single bond, a1 denotes 1 or 2 and a2 denotes 0.
  • the compounds of the formula I (see WO 92/09576) can be synthesized using the method as described by V. Reiffenrath et al. in Angew. Chem., 106, No.13, (1994).
  • the compounds of the formula I are selected from the group consisting of compounds of the formulae IA, IB, IC, ID, and IE,
  • Preferred compounds of the formulae IA, IB, IC and ID are those wherein R 12 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, and very preferably denotes (O)CvH2v+1 wherein (O) is an oxygen atom or a single bond and v is 1, 2, 3, 4, 5 or 6.
  • LC medium comprises one or more compounds of the formula IA selected from the group consisting of the following formulae:
  • alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms
  • (O) denotes an oxygen atom or a single bond
  • Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IA-2, IA-4, IA-6, IA-8, IA-10, IA-22, IA-23, IA-24, IA-25 and IA-32 to IA-36.
  • the LC medium comprises one or more compounds of the formula IA-2 selected from the following subformulae:
  • the LC medium comprises one or more compounds of the following formulae:
  • the LC medium comprises one or more compounds of the formula IA- 6 selected from the following sub-formulae:
  • the LC medium comprises one or more compounds of the following formulae:
  • Preferred LC media additionally comprise one or more compounds of formula IA-0 in which R 11 and R 12 have one of the meanings given in formula IA above.
  • Preferred compounds of the formula IA-0 are selected from the group consisting of the following subformulae in which, Alkyl and Alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, Alkoxy and Alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms, and O denotes an oxygen atom or a single bond.
  • Particularly preferred compounds of the formula IA-0 are selected from the group consisting of subformula IA-0-6, in which Alkoxy has the meanings defined above and preferably denotes methoxy, ethoxy, n- propyloxy, n-butyloxy or n-pentyloxy.
  • the LC medium comprises one or more compounds of the formula IB selected from the group consisting of the following formulae:
  • alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms
  • (O) denotes an oxygen atom or a single bond
  • LC media comprise one or more compounds selected from the group consisting of formulae IB-2, IB-6 and IB-8.
  • the LC medium comprises one or more compounds of the formula IB-6 selected from the following sub-formulae:
  • the LC medium comprises one or more compounds of the following formulae:
  • the LC medium comprises one or more compounds of the formula IC selected from the formula IC-1, in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, preferably in amounts of 0.5% to 5 % by weight, in particular 1% to 3 % by weight.
  • the LC medium comprises one or more compounds of the formula ID selected from the group consisting of the following formulae,
  • alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms
  • (O) denotes an oxygen atom or a single bond
  • Y denotes H or CH 3
  • Particularly preferred LC media according to the invention comprise one or more compounds of the formula ID-1 and/or ID-2.
  • Very preferred compounds of the formula ID are compounds of the formula ID-5 selected from the following subformulae,
  • the LC medium comprises one or more compounds of formula ID-5a in which R 11 , Y and q have the meanings given in formula ID, and R 13 is , in which r is 0, 1, 2, 3, 4, 5 or 6 and s is 1, 2 or 3.
  • Preferred compounds of formula IID-5a are selected from the following subformulae:
  • Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IE-1, IE-2, IE-3, IE-4, IE-5.
  • the proportion of compounds of the formulae IA and/or IB in the mixture as a whole is preferably at least 20 % by weight.
  • Particularly preferred LC media according to the invention comprise one or more compounds selected from the formulae IA-2, IA-4, IA-6, IA-8, I-10, IA-22, IA-23, IA-24, IA-25, IB-2, IB-6, IB-8, IC-1, ID-2, ID-5, IE-1, IE-2, IE-3, IE-4, IE-5, or their subformulae.
  • the invention further relates to the use of the LC medium as described above and below in LC displays, preferably in LC displays of the VA, IPS, FFS, UB-FFS or UBplus mode.
  • the invention furthermore relates to a process for preparing an LC medium as described above and below, comprising the steps of mixing one or more compounds of formula I with one or more compounds as described below and optionally with further LC compounds and/or additives.
  • the invention furthermore relates to an LC display comprising an LC medium according to the invention as described above and below, preferably an LC display of the VA, IPS, FFS, UB-FFS or UBplus mode.
  • the invention furthermore relates to a process for manufacturing an LC display as described above and below, comprising the steps of filling or otherwise providing an LC medium as described above and below between the substrates of the display.
  • the LC media according to the present invention allow to achieve one or more of the following advantageous effects: - a favourably high average elastic constant Kavg that equals to (K1+K2+K3)/3, which contributes to a high contrast ratio, - a favourably low ratio of rotational viscosity to the splay elastic constant ⁇ 1 / K 11 , which contributes to improved switching behaviour especially at low driving voltages and is useful to enable energy-saving displays.
  • the LC media according to the present invention show one or more of the following advantageous properties when used in LC displays: - high contrast ratio, - high transmittance, - reduced rotational viscosity, - fast response times, - a low threshold voltage which is useful to enable energy-saving displays.
  • the LC media according to the present invention show a favourable combination of low rotational viscosity and high average elastic constant Kavg.
  • a low rotational viscosity and therefore the low ratio of rotational viscosity to the splay elastic constant ⁇ 1 / K 11 improves switching behaviour especially at low driving voltages.
  • an increased Kavg enables the realisation of a low scattering parameter and thereby a high contrast ratio.
  • the LC media according to the present invention show high VHR values and less or no undesired mura effects such as edge mura.
  • denotes a trans-1,4-cyclohexylene ring denotes a 1,4-phenylene ring.
  • the single bond shown between the two ring atoms can be attached to any free position of the benzene ring.
  • a terminal group like R 11,12 , R 21,22 , R 31, 32, 33 , R 41,42 , R 51,52 , R 61 , R 71 , R N1,N2 , R 81,82 , R 91,92,93 , R L1,L2 , R Q , R R1 ,R2 , or L denotes an alkyl radical and/or an alkoxy radical, this may be straight-chain or branched.
  • It is preferably straight-chain, has 2, 3, 4, 5, 6 or 7 C atoms and accordingly preferably denotes ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexyloxy or heptyloxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.
  • one of the aforementioned terminal groups denotes an alkyl radical wherein one or more CH 2 groups are replaced by S, this may be straight-chain or branched. It is preferably straight-chain, has 1, 2, 3, 4, 5, 6 or 7 C atoms and accordingly preferably denotes thiomethyl, thioethyl, thiopropyl, thiobutyl, thiopentyl, thiohexyl or thioheptyl.
  • one of the aforementioned terminal groups denotes an alkyl or alkenyl radical which is at least monosubstituted by halogen
  • this radical is preferably straight-chain, and halogen is preferably F or Cl.
  • halogen is preferably F.
  • the resultant radicals also include perfluorinated radicals.
  • the fluorine or chlorine substituent may be in any desired position, but is preferably in the ⁇ -position.
  • one or more of the aforementioned terminal groups are selected from the group consisting of -S 1 -F, -O-S 1 -F, -O-S 1 -O-S 2 , wherein S 1 is C 1-12 -alkylene or C 2-12 -alkenylene and S 2 is H, C 1-12 -alkyl or C 2-12 -alkenyl, and very preferably are selected from the group consisting of Halogen is preferably F or Cl, very preferably F.
  • substituents L are, for example, F, Cl, CN, NO 2 , CH 3 , C 2 H 5 , OCH 3 , OC 2 H 5 , COCH 3 , COC 2 H 5 , COOCH 3 , COOC 2 H 5 , CF 3 , OCF 3 , OCHF 2 , OC 2 F 5 , furthermore phenyl. in which L has one of the meanings indicated above.
  • Further preferred embodiments of the LC medium according to the present invention are listed below, including any combination thereof.
  • the LC medium further comprises one or more compounds of formula II,
  • Preferred compounds of the formulae IIA, IIB, IIC, IID and IIE are those wherein R 22 denotes an alkyl or alkoxy radical having up to 15 C atoms, and very preferably denotes (O)CvH2v+1, wherein (O) is an oxygen atom or a single bond and v is 1, 2, 3, 4, 5 or 6.
  • LC medium comprises one or more compounds of the formula IIA selected from the group consisting of the following formulae:
  • alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms
  • (O) denotes an oxygen atom or a single bond
  • LC media comprise one or more compounds selected from the group consisting of formulae IIA-2, IIA-8, IIA-10, IIA-16, IIA-18, IIA-40, IIA-41, IIA-42 and IIA-43.
  • the LC medium comprises one or more compounds of the formula IIA-2 selected from the following subformulae:
  • the LC medium comprises one or more compounds of the following formulae:
  • the LC medium comprises one or more compounds of the formula IIA-10 selected from the following sub-formulae:
  • the LC medium comprises one or more compounds of the following formulae:
  • Preferred LC media additionally comprise one or more compounds of formula IIA-Y in which R 21 and R 22 have one of the meanings given in formula IIA above, and L 1 and L 2 , identically or differently, denote F or Cl.
  • Preferred compounds of the formula IIA-Y are selected from the group consisting of the following subformulae in which, Alkyl and Alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl* each, independently of one another, denote a straight- chain alkenyl radical having 2-6 C atoms, and O denotes an oxygen atom or a single bond.
  • Particularly preferred compounds of the formula IIA-Y are selected from the group consisting of following subformulae: in which Alkoxy and Alkoxy* have the meanings defined above and preferably denote methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy.
  • the LC medium comprises one or more compounds of the formula IIB selected from the group consisting of formulae IIB-1 to IIB-30,
  • alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms
  • (O) denotes an oxygen atom or a single bond
  • LC media comprise one or more compounds selected from the group consisting of formulae IIB-2, IIB-10 and IIB-16.
  • the LC medium comprises one or more compounds of the formula IIB-10 selected from the following sub-formulae:
  • the LC medium comprises one or more compounds of the formulae IIB-10a-1 to IIB- 10a-5:
  • the LC medium comprises one or more compounds of the formula IIC selected from the formula IIC-1, in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, preferably in amounts of 0.5% to 5 % by weight, in particular 1% to 3 % by weight.
  • Particularly preferred LC media according to the invention comprise one or more compounds of the formula IID-1 and/or IID-4. Very preferred compounds of the formula IID are selected from the following subformulae of IID-1
  • the LC medium comprises one or more compounds of formula IID-14a in which R 21 , Y and q have the meanings given in formula IID, and R 23 is , in which r is 0, 1, 2, 3, 4, 5 or 6 and s is 1, 2 or 3.
  • Preferred compounds of formula IID-14a are the compounds IID-14a-1 to IID-14a-14: Very preferred compounds of the formula IID are selected from the following subformulae of IID-17, wherein v is 1, 2, 3, 4, 5 or 6.
  • R 31 and R 32 each, independently of one another, denote H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by F, Cl, CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups in these radicals may be replaced by -O-, -S-,
  • R 31 and R 32 are preferably selected from straight-chain alkyl or alkoxy with 1 to 12, preferably 1 to 7 C atoms, straight-chain alkenyl with 2 to 12, preferably 2 to 7 C atoms and cyclic alkyl or alkoxy with 3 to 12, preferably 3 to 8 C atoms.
  • the LC medium comprises one or more compounds of formula III selected from the subformulae III-1 to III-6:
  • R 31 and R 32 each, independently of one another, denote an alkyl, alkenyl or alkoxy radical having up to 15 C atoms, preferably having 1 to 7 C atoms, more preferably one or both of them denote an alkoxy radical; or cyclic alkyl having 3 to 6 C atoms, R 33 denotes alkyl or alkenyl having up to 7 C atoms or a group Cy-C n H 2n+1 -, m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, which is optionally substituted with alkyl or alkenyl each having up to 3 C atoms, or with halogen or CN, and preferably denotes cyclopropyl, cyclobutyl, cyclopentyl or cyclopenten
  • alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms
  • alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms
  • L 31 and L 32 each, independently of one another, denote F or Cl, preferably both F.
  • Very preferred compounds of formula III-1-1 are selected from the group consisting of the following subformulae,
  • alkoxy denotes a straight-chain alkoxy radical having 1, 2, 3 or 4 C atoms.
  • Very preferred compounds of the formula III-2 are the following,
  • alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms, preferably ethoxy, propoxy, butoxy or pentoxy, very preferably ethoxy or propoxy.
  • Very preferred compounds of formula III-6 are selected from the group consisting of the following formulae, in which R 32 denotes alkyl having 1 to 7 C-atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl or alternatively – (CH 2 ) n F in which n is 2,3,4, or 5, preferably C 2 H 4 F.
  • the LC medium comprises one or more compounds of formula IIIA selected from the subformulae IIIA-1 to IIIA-6: in which the occurring groups have the same meanings as given under formula III above and preferably R 31 and R 32 each, independently of one another, denote an alkyl, alkenyl or alkoxy radical having up to 15 C atoms, preferably having 1 to 7 C atoms, more preferably one or both of them denote an alkoxy radical; or cyclic alkyl having 3 to 6 C atoms, R 33 denotes alkyl or alkenyl having up to 7 C atoms or a group Cy-C n H 2n+1 -, m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, which is optionally substituted with alkyl or alkenyl each having up to 3 C atoms, or with
  • alkyl and alkyl* each, independently of one another denote a straight-chain alkyl radical having 1-6 C atoms
  • alkenyl and alkenyl* each, independently of one another denote a straight-chain alkenyl radical having 2-6 C atoms
  • alkoxy and alkoxy* each, independently of one another denote a straight-chain alkoxy radical having 1-6 C atoms
  • the LC medium comprises one or more compounds of the formula IV, in which R 41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms where, in addition, one or more CH 2 groups may be replaced by or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2, 3, 4 or 5 C atoms, and R 42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, both preferably having 2 to 5 C atoms, or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably a vinyl radical or a 1-propenyl radical and in particular a vinyl radical.
  • R 41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms where, in addition, one or more CH 2
  • the LC medium according to the invention comprises one or more compounds of the formulae IV-2-1 and/or IV-2-2
  • the LC medium according to the invention comprises a compound of formula IV-3, in particular selected from the compounds of the following subformulae:
  • the LC medium according to the invention preferably comprises one or more compounds CC-n-V and/or CC-n-Vm, in particular CC-3-V, CC-4-V, CC-3-V1 and/or CC-4-V1, preferably in a total concentration in the range of from 15 to 60 %, preferably from 18 to 52 %.
  • CC-3-V is preferably used in concentrations of 5-50 %, in particular 6-45 %.
  • the LC medium according to the invention comprises a compound of formula IV-4, in particular selected from the compounds of the following formulae:
  • the LC medium comprises one or more compounds of formula IV-4 and its subformulae in which one or both of "alkenyl” and “alkenyl' " denote in which m is 0, 1 or 2, and n is 0, 1 or 2, very preferably selected from compounds of formulae IV-4-3 to IV-4-6.
  • the proportion of compounds of the formula IVa in the mixture as a whole is preferably at least 5 % by weight
  • the LC medium comprises one or more compounds of formula IVb-1 to IVb- 3 in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2 to 6 C atoms.
  • the proportion of the compounds of the formulae IV-1 to IV-3 in the mixture as a whole is preferably at least 3 % by weight, in particular ⁇ 5 % by weight.
  • the compounds of the formula IVb-2 are particularly preferred.
  • Particularly preferred compounds of the formulae IV-1 to IV-3 are selected from the group consisting of the following formulae in which alkyl* denotes an alkyl radical having 1 to 6 C atoms and preferably denotes n- propyl.
  • the LC medium according to the invention particularly preferably comprises one or more compounds of the formulae IVb-1-1 and/or IVb-2-3.
  • the LC medium according to the invention comprises one or more compounds of formula V in which R 51 and R 52 independently of one another, denote H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by F, Cl, CN or CF 3 or at least monosubstituted by halogen, where, in addition, one or more CH 2 groups in these radicals may be replaced by -O-, -S-,-C ⁇ C-, -CF 2 O-, -OCF 2 -, -OC-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and preferably denote alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy having 1 to 6 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy
  • LC media comprise one or more compounds of the formulae V-1, V-3, V-4, V- 6, V-7, V-10, V-11, V-12, V-14, V-15, and/or V-16.
  • LC media according to the invention very particularly preferably comprise the compounds of the formula V-10 and/or IV-1, in particular in amounts of 5 to 30 %.
  • Preferred compounds of the formulae V-10 are indicated below:
  • the LC medium according to the invention particularly preferably comprises the tricyclic compounds of the formula V-10a and/or of the formula V-10b in combination with one or more bicyclic compounds of the formulae IV-1
  • the total proportion of the compounds of the formulae V-10a and/or V-10b in combination with one or more compounds selected from the bicyclohexyl compounds of the formula IV-1 is 5 to 40 %, very particularly preferably 15 to 35 %.
  • Particularly preferred LC media comprise the compounds V-10a and/or IV-1-1
  • the compounds V-10a and IV-1-1 are preferably present in the mixture in a concentration of 5 to 30 %, very preferably 10 to 25 %, based on the mixture as a whole.
  • Preferred LC media comprise at least one compound selected from the group of the compounds
  • R 51 , R 52 , R 41 and R 42 have the meanings indicated above.
  • R 51 and R 41 denotes alkyl or alkenyl having 1 to 6 or 2 to 6 C atoms, respectively
  • R 52 and R 42 denotes alkenyl having 2 to 6 C atoms.
  • R 51 denotes alkyl or alkenyl having 1 to 6 or 2 to 6 C atoms
  • R 52 denotes alkyl having 1 to 6 C atoms, or alkoxy having 2 to 6 C atoms.
  • the LC medium according to the invention comprises one or more compounds of the formula V-7, preferably selected from the compounds of the formulae V-7a to V-7e: in which alkyl denotes an alkyl group having 1 to 7 C atoms, alkenyl denotes an alkenyl group having 2 to 7 C atoms, and cycloalkyl denotes a cyclic alkyl group having 3 to 12 C atoms, preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylalkyl, cyclobutylalkyl or cyclopentylalkyl.
  • Very preferred compounds of the formulae V-7a to V-7e are selected from the compounds of the following subformulae:
  • alkyl denotes ethyl, n-propyl, n-butyl or n-pentyl, preferably n-propyl.
  • R 51 and R 52 independently of one another denote straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms.
  • the LC medium additionally comprises one or more compounds of the formulae VI-1 to VI-25, in which R 61 denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms, cycloalkyl having 3 to 6 C atoms, (O) denotes -O- or a single bond, X denotes F, Cl, OCF 3 or OCHF 2 , L x denotes H or F, m is 0, 1, 2, 3, 4, 5 or 6 and n is 0, 1, 2, 3 or 4.
  • R 61 preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentoxy.
  • X preferably denotes F or OCH 3 , very preferably F.
  • the LC medium according to the invention preferably comprises the terphenyls of the formulae VI-1 to VI-25 in amounts of 2 to 30 % by weight, in particular 5 to 20 % by weight. Particular preference is given to compounds of the formulae VI-1, VI-2, VI-4, VI-20, VI- 21, and VI-22 wherein X denotes F.
  • R 61 preferably denotes alkyl, furthermore alkoxy, each having 1 to 5 C atoms.
  • R 61 preferably denotes alkyl or alkenyl, in particular alkyl.
  • R 61 preferably denotes alkyl.
  • X preferably denotes F.
  • the terphenyls of formula VI-1 to VI-25 are preferably employed in the LC media according to the invention if the ⁇ n value of the mixture is to be ⁇ 0.1.
  • Preferred LC media comprise 2 to 20 % by weight of one or more terphenyl compounds selected from the group of the compounds of formulae VI-1 to VI-25.
  • the LC medium additionally comprises one or more compounds of the formulae VII-1 to VII-9 in which R 71 each, independently of one another, have one of the meanings indicated for R 21 in formula IIA, and w and x each, independently of one another, denote 1 to 6. Particular preference is given to LC media comprising at least one compound of the formula VII-9.
  • the LC medium according to the invention preferably comprises the compounds of the formulae BC, CR, PH-1, PH-2 in amounts of 3 to 20 % by weight, in particular in amounts of 3 to 15 % by weight.
  • Particularly preferred compounds of the formulae BC and CR are the compounds BC-1 to BC-7 and CR-1 to CR-5,
  • alkyl and alkyl* each, independently of one another denote a straight-chain alkyl radical having 1 to 6 C atoms
  • alkenyl and alkenyl* each, independently of one another denote a straight-chain alkenyl radical having 2 to 6 C atoms.
  • an LC medium comprising one, two or three compounds of the formula BC-2, BF-1 and/or BF-2.
  • Particularly preferred compounds of the formula BC the compounds B(A)-2O- O2
  • Particularly preferred compounds of the formula PH-1 the compounds B(P)-2O- O3 and B(P)-2O-O4,
  • LC medium comprising one or more indane compounds of the formula In, in which R 91 , R 92 , R 93 each, independently of one another, denote a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl radical having 1 to 6 C atoms, R 92 and R 93 may also denote halogen, preferably F, i denotes 0, 1 or 2.
  • Preferred compounds of the formula In are the compounds of the formulae In-1 to In-16 indicated below:
  • alkyl denotes an alkyl radical having 1 to 6 C atoms
  • s denotes 1 or 2.
  • the compounds of the formulae L-1 to L8 are preferably employed in concentrations of 5 to 15 % by weight, in particular 5 to 12 % by weight and very particularly preferably 8 to 10 % by weight.
  • LC medium comprising one or more quaterphenyl compounds selected from the following formula: wherein R Q is alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, X Q is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L Q1 to L Q6 independently of each other are H or F, with at least one of L Q1 to L Q6 being F.
  • the compounds of formula Q are preferably selected from the following subformulae wherein R Q has one of the meanings of formula Q or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl. Especially preferred are compounds of formula Q1, in particular those wherein R Q is n-propyl.
  • the proportion of compounds of formula Q in the LC medium is from >0 to ⁇ 5% by weight, very preferably from 0.05 to 2% by weight, more preferably from 0.1 to 1% by weight, most preferably from 0.1 to 0.8% by weight.
  • the LC medium contains 1 to 5, preferably 1 or 2 compounds of formula Q.
  • quaterphenyl compounds of formula Q to the LC mixture of a polymerizable LC medium enables to reduce ODF mura, whilst maintaining high UV absorption, enabling quick and complete polymerization, enabling strong and quick tilt angle generation, and increasing the UV stability of the LC medium.
  • compounds of formula Q which have positive dielectric anisotropy
  • to the LC medium with negative dielectric anisotropy allows a better control of the values of the dielectric constants and , and in particular enables to achieve a high value of the dielectric constant while keeping the dielectric anisotropy ⁇ ⁇ constant, thereby reducing the kick-back voltage and reducing image sticking.
  • the LC medium according to the invention preferably comprises - one or more compounds of formula I or its subformulae in a proportion from 1 to 25%, very preferably from 2 to 22 %, most preferably from 2.5 to 20% by weight; and/or - one or more compounds of formula IIA, IIB, and/or IID, preferably in a total concentration in the range of from 20 to 65%, more preferably from 25 to 60%, particularly preferably from 30 to 55%; wherein formula IIA preferably in a total concentration in the range of 5 to 30%; wherein formula IIB preferably in a total concentration in the range of 1 to 5%; wherein formula IID preferably in a total concentration in the range of 10 to 35%; wherein the total concentration of one or more compounds of formula I and IIA is preferably in the range from 10 to 45%, more preferably from 15 to 30%, most preferably from 17 to 28% by weight; wherein the total concentration of one or more compounds of formula I and IID is preferably in the range from 10 to 50%, more preferably from 15
  • the liquid-crystalline medium according to the invention preferably have a nematic phase from ⁇ -20°C to ⁇ 70°C, particularly preferably from ⁇ -30°C to ⁇ 80°C, very particularly preferably from ⁇ -40°C to ⁇ 90°C.
  • the LC medium according to the invention preferably has a clearing temperature of 90°C or more, more preferably of 95°C or more.
  • the expression "have a nematic phase” here means on the one hand that no smectic phase and no crystallisation are observed at low temperatures at the corresponding temperature and on the other hand that clearing still does not occur on heating from the nematic phase.
  • the investigation at low temperatures is carried out in a flow viscometer at the corresponding temperature and checked by storage in test cells having a layer thickness corresponding to the electro-optical use for at least 100 hours. If the storage stability at a temperature of -20°C in a corresponding test cell is 1000 h or more, the LC medium is referred to as stable at this temperature. At temperatures of -30°C and -40°C, the corresponding times are 500 h and 250 h respectively. At high temperatures, the clearing point is measured by conventional methods in capillaries.
  • the liquid-crystal mixture preferably has a nematic phase range of at least 60 K and a flow viscosity v 20 of at most 30 mm 2 ⁇ s -1 at 20°C.
  • the mixture is nematic at a temperature of -20°C or less, preferably at -30°C or less, very preferably at -40°C or less.
  • the values of the birefringence ⁇ n in the liquid-crystal mixture are generally between 0.07 and 0.16, preferably between 0.08 and 0.15, very preferably between 0.09 and 0.14.
  • the LC medium has a birefringence in the range of from 0.090 to 0.110, preferably from 0.090 to 0.108.
  • the liquid-crystal mixture according to the invention has a dielectric anisotropy ⁇ ⁇ of -1.5 to -8.0, preferably of -3.0 to -6.0, in particular --3.8 to -4.5,
  • the rotational viscosity ⁇ 1 at 20°C is preferably ⁇ 250 mPa ⁇ s, more preferably ⁇ 200 mPa ⁇ s, very preferably ⁇ 180mPa ⁇ s, in particular ⁇ 160 mPa ⁇ s.
  • the liquid-crystal media according to the invention have relatively low values for the threshold voltage (V0). They are preferably in the range from 1.7 V to 3.0 V, particularly preferably ⁇ 2.7 V and very particularly preferably ⁇ 2.5 V.
  • the term "threshold voltage” relates to the capacitive threshold (V0), also called the Freedericks threshold, unless explicitly indicated otherwise.
  • the liquid-crystal media according to the invention have high values for the voltage holding ratio in liquid-crystal cells. In general, liquid-crystal media having a low addressing voltage or threshold voltage exhibit a lower voltage holding ratio than those having a higher addressing voltage or threshold voltage and vice versa.
  • dielectrically positive compounds denotes compounds having a ⁇ ⁇ > 1.5
  • dielectrically neutral compounds denotes those having -1.5 ⁇ ⁇ ⁇ ⁇ 1.5
  • dielectrically negative compounds denotes those having ⁇ ⁇ ⁇ -1.5.
  • the dielectric anisotropy of the compounds is determined here by dissolving 10 % of the compounds in a liquid-crystalline host and determining the capacitance of the resultant mixture in at least one test cell in each case having a layer thickness of 20 ⁇ m with homeotropic and with homogeneous surface alignment at 1 kHz.
  • the measurement voltage is typically 0.5 V to 1.0 V, but is always lower than the capacitive threshold of the respective liquid-crystal mixture investigated. All temperature values indicated for the present invention are in °C.
  • the LC media according to the invention are suitable for all VA-TFT (vertical alignment- thin film transistor) applications, such as, for example, VAN (vertically aligned nematic), MVA (multidomain VA), (S)-PVA (super patterned VA), ASV (advanced super view, or axially symmetric VA), and PSA (polymer sustained VA). They are furthermore suitable for IPS (in-plane switching) and FFS (fringe field switching) applications having negative ⁇ ⁇ .
  • the LC medium preferably comprises 4 to 15, in particular 5 to 12, and particularly preferably ⁇ 10, compounds of the formulae IIA, IIB, IIC, IID, IIE and/or III and one or more compounds of the formula IV.
  • other constituents may also be present, for example in an amount of up to 45 % of the mixture as a whole, but preferably up to 35 %, in particular up to 10 %.
  • the other constituents are preferably selected from nematic or nematogenic substances, in particular known substances, from the classes of the azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl cyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbiphenyls or cyclohexylpyrimidines, phenyl- or cyclohexyldioxanes, optionally halogenated stilbenes, benzyl phenyl ethers, tolanes and substituted cinnamic acid esters.
  • nematic or nematogenic substances
  • R R1 and R R2 are different from one another, one of these radicals usually being an alkyl or alkoxy group.
  • Other variants of the proposed substituents are also common. Many such substances or also mixtures thereof are commercially available. All these substances can be prepared by methods known from the literature. It goes without saying for the person skilled in the art that the VA, IPS or FFS mixture according to the invention may also comprise compounds in which, for example, H, N, O, Cl and F have been replaced by the corresponding isotopes.
  • the LC medium has preferably a nematic LC phase.
  • the LC media contain one or more chiral dopants, preferably in a concentration from 0.01 to 1% by weight, very preferably from 0.05 to 0.5% by weight.
  • the chiral dopants are preferably selected from the group consisting of compounds from Table C below, very preferably from the group consisting of R- or S- 1011, R- or S-2011, R- or S-3011, R- or S-4011, and R- or S-5011.
  • the LC media contain a racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph.
  • the LC media contain one or more further stabilisers.
  • Preferred stabilisers are selected from the compounds of formula H in which Ar denotes an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms, preferably 6 to 30 C atoms; Sp denotes a spacer group; R S denotes H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms; Z S denotes -O-, -C(O)O-, -(CH 2 )z- or –(CH 2 ) z O-, or a single bond; HA denotes R H denotes H, O . , CH 3 , OH or OR S , preferably H or O .
  • R S1 , R S2 , R S3 and R S4 identically or differently, denote alkyl having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH 3 ;
  • G denotes H or R S or a group Z S -HA;
  • z is an integer from 1 to 6; and
  • q is 3 or 4.
  • the compounds of formula H are described in EP3354710 A1 and EP3354709 A1.
  • Preferred compounds of formula H are selected from the formulae H-1, H-2 and H-3: in which R H has the meanings given above and preferably denotes H or O .
  • n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7, and Sp denotes a spacer group, preferably alkylene having 1 to 12 C atoms in which one or more non-adjacent - CH 2 - groups may be replaced with -O-.
  • Preferred compounds of formula H-1 are those of formula H-1-1:
  • R H has the meanings given above and preferably denotes H or O .
  • n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.
  • Very preferred compounds of formula H-1-1 are those of formula H-1-1-1:
  • Preferred compounds of formula H-2 are those of formula H-2-1:
  • R H has the meanings given above and preferably denotes H or O .
  • n2 on each occurrence identically or differently, preferably identically, is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, and R S on each occurrence identically or differently, preferably identically, denotes alkyl having 1 to 6 C atoms, preferably n- butyl.
  • Very preferred compounds of formula H-2-1 are those of formula H-2-1-1:
  • Preferred compounds of formula H-3 are selected from the formula H-3-1:
  • n preferably denotes 3.
  • n preferably denotes 7.
  • Very preferred stabilisers are selected from the group of the compounds of the formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12:
  • the LC medium comprises one or more stabilisers selected from Table D below.
  • the proportion of stabilisers in the LC medium is from 10 to 500 ppm, very preferably from 20 to 100 ppm.
  • the LC medium according to the present invention may additionally comprise one or more further components or additives, preferably selected from the list including but not limited to co-monomers, chiral dopants, polymerization initiators, inhibitors, stabilisers, surfactants, wetting agents, lubricating agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents, reactive diluents, auxiliaries, colourants, dyes, pigments and nanoparticles.
  • further components or additives preferably selected from the list including but not limited to co-monomers, chiral dopants, polymerization initiators, inhibitors, stabilisers, surfactants, wetting agents, lubricating agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents, reactive diluents, auxiliaries, colourants, dyes, pigments and nano
  • LC media for example, 0 to 15% by weight of pleochroic dyes, furthermore nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst.24, 249-258 (1973)), for improving the conductivity, or substances for modifying the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases.
  • conductive salts preferably ethyldimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq.
  • the LC media which can be used in accordance with the invention are prepared in a manner conventional per se, for example by mixing one or more of the above-mentioned compounds with one or more polymerizable compounds as defined above, and optionally with further liquid-crystalline compounds and/or additives.
  • the desired amount of the components used in lesser amount is dissolved in the components making up the principal constituent, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation, after thorough mixing.
  • the invention furthermore relates to the process for the preparation of the LC media according to the invention.
  • the LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes like deuterium etc.
  • the following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combina- tions are accessible. For the present invention and in the following examples, the structures of the liquid- crystal compounds are indicated by means of acronyms. Unless stated otherwise, the transformation into chemical formulae is done in accordance with Tables A.1 to A.3 below.
  • All radicals C n H 2n+1 , C m H 2m+1 and ClH2l+1 or C n H 2n , C m H 2m and ClH2l are straight-chain alkyl radicals or alkylene radicals, in each case having n, m and l C atoms respectively.
  • n, m and l are independently of each other 1, 2, 3, 4, 5, 6, or 7.
  • Table A.1 shows the codes for the ring elements of the nuclei of the compound
  • Table A.2 lists the bridging units
  • Table A.3 lists the meanings of the symbols for the left- and right-hand end groups of the molecules.
  • the acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group.
  • n, m, k and l are, independently of one another, each an integer, preferably 1 to 9 preferably 1 to 7, k and l may also be 0 and are preferably 0 to 4, more preferably 0 or 2 and most preferably 2, n is preferably 1, 2, 3, 4 or 5 or, in the combination “-nO-”, n is preferably 1, 2, 3 or 4, very preferably 2 or 4, m is preferably 1, 2, 3, 4 or 5 or, in the combination “-Om”, m is preferably 1, 2, 3 or 4, more preferably 2 or 4.
  • the combination “-nVm” preferably is “2V1”.
  • (O)C m H 2m+1 means C m H 2m+1 or OC m H 2m+1 .
  • the LC media according to the invention comprise one or more compounds selected from the group consisting of compounds from Table B.
  • Table C shows possible chiral dopants which can be added to the LC media according to the invention with the concentration from 0 to 5 wt %, preferably 0.01 to 3 wt %. ⁇
  • the LC media preferably comprise 0 to 10% by weight, in particular 0.01 to 5% by weight, particularly preferably 0.1 to 3% by weight, of dopants.
  • the LC media preferably comprise one or more dopants selected from the group consisting of compounds from Table C.
  • Table D Table D shows possible stabilisers which can be added to the LC media according to the invention.
  • n denotes an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups are not shown.
  • the LC media preferably comprise 0 to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 1 ppm to 1% by weight, of stabilisers.
  • the LC media preferably comprise one or more stabilisers selected from the group consisting of compounds from Table D. Examples The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combina- tions are accessible.
  • threshold voltage for the present invention relates to the capacitive threshold (V0), also known as the Freedericks threshold, unless explicitly indicated otherwise.
  • the optical threshold may also, as generally usual, be quoted for 10% relative contrast (V10).
  • the process of polymerizing the polymerizable compounds in the PSA displays as described above and below is carried out at a temperature where the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably is carried out at room temperature.
  • methods of preparing test cells and measuring their electrooptical and other properties are carried out by the methods as described hereinafter or in analogy thereto.
  • the polymerizable compounds are polymerized in the display or test cell by irradiation with UV light of defined intensity for a prespecified time, with a voltage simultaneously being applied to the display (usually 10 V to 30 V alternating current, 1 kHz).
  • tilt angle means the angle between the LC director and the substrate, and "LC director” means in a layer of LC molecules with uniform orientation the preferred orientation direction of the optical main axis of the LC molecules, which corresponds, in case of calamitic, uniaxially positive birefringent LC molecules, to their molecular long axis.
  • the following compounds A-1, A-2, B-1 to B-7, C, D, and/or E of formula I are added to the LC mixtures.
  • Example 1A The nematic LC mixture N1A is formulated as follows. To the mixture N1A are added 100 ppm of the stabiliser H-1-1-1.
  • Example 1B The nematic LC mixture N1B is formulated as follows. To the mixture N1B are added 100 ppm of the stabiliser H-1-1-1.
  • Example 1C The nematic LC mixture N1Cis formulated as follows. To the mixture N1C are added 100 ppm of the stabiliser H-1-1-1.
  • Example 1D The nematic LC mixture N1D is formulated as follows. To the mixture N1D are added 100 ppm of the stabiliser H-1-1-1.
  • Example 1E The nematic LC mixture N1E is formulated as follows.
  • Example 2 The nematic LC mixture N2 is formulated as follows. To the mixture N2 are added 150 ppm of the stabiliser ST-3a-1. Example 3 The nematic LC mixture N3 is formulated as follows.
  • Example 4 The nematic LC mixture N4 is formulated as follows.
  • Example 5 The nematic LC mixture N5 is formulated as follows.
  • Example 6 The nematic LC mixture N6 is formulated as follows. To the mixture N6 are added 50 ppm of the stabiliser ST-9-1.
  • Example 7 The nematic LC mixture N7 is formulated as follows. To the mixture N7 are added 50 ppm of the stabiliser ST-12.
  • Example 8 The nematic LC mixture N8 is formulated as follows. To the mixture N8 are added 100 ppm of the stabiliser H-1-1-1.
  • Example 9 The nematic LC mixture N9 is formulated as follows.
  • Example 10 The nematic LC mixture N10 is formulated as follows.
  • Example 11 The nematic LC mixture N11 is formulated as follows. To the mixture N11 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 13 The nematic LC mixture N13 is formulated as follows.
  • Example 15 The nematic LC mixture N15 is formulated as follows. To the mixture N15 are added 50 ppm of the stabiliser ST-12.
  • Example 16 The nematic LC mixture N16 is formulated as follows.
  • Example 17 The nematic LC mixture N17 is formulated as follows. To the mixture N17 are added 150 ppm of the stabiliser ST-3a-1. Example 18 The nematic LC mixture N18 is formulated as follows.
  • Example 22 The nematic LC mixture N22 is formulated as follows. To the mixture N22 are added 50 ppm of the stabiliser ST-12. Example 23 The nematic LC mixture N23 is formulated as follows.
  • Example 24 The nematic LC mixture N24 is formulated as follows. To the mixture N24 are added 150 ppm of the stabiliser ST-3a-1. To the mixture N25 are added 150 ppm of the stabiliser ST-3b-1.
  • Example 26 The nematic LC mixture N26 is formulated as follows. To the mixture N26 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 27 The nematic LC mixture N27 is formulated as follows. To the mixture N27 are added 100 ppm of the stabiliser ST-8-1.
  • Example 28 The nematic LC mixture N28 is formulated as follows. To the mixture N28 are added 50 ppm of the stabiliser ST-9-1.
  • Example 29 The nematic LC mixture N29 is formulated as follows. To the mixture N29 are added 50 ppm of the stabiliser ST-12.
  • Example 30 The nematic LC mixture N30 is formulated as follows.
  • Example 31 The nematic LC mixture N31 is formulated as follows. To the mixture N31 are added 150 ppm of the stabiliser ST-3a-1.
  • Example 32 The nematic LC mixture N32 is formulated as follows.
  • Example 33 The nematic LC mixture N33 is formulated as follows. To the mixture N33 are added 50 ppm of the stabiliser H-2-1-1. Example 34 The nematic LC mixture N34 is formulated as follows.
  • Example 35 The nematic LC mixture N35 is formulated as follows. To the mixture N35 are added 50 ppm of the stabiliser ST-9-1.
  • Example 36 The nematic LC mixture N36 is formulated as follows. To the mixture N36 are added 50 ppm of the stabiliser ST-12.
  • Example 37 The nematic LC mixture N37 is formulated as follows.
  • Example 38 The nematic LC mixture N38 is formulated as follows. To the mixture N38 are added 150 ppm of the stabiliser ST-3a-1. Example 39 The nematic LC mixture N39 is formulated as follows.
  • Example 40 The nematic LC mixture N40 is formulated as follows. To the mixture N40 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 41 The nematic LC mixture N41 is formulated as follows.
  • Example 42 The nematic LC mixture N42 is formulated as follows. To the mixture N42 are added 50 ppm of the stabiliser ST-9-1.
  • Example 43 The nematic LC mixture N43 is formulated as follows. To the mixture N43 are added 50 ppm of the stabiliser ST-12.
  • Example 44 The nematic LC mixture N44 is formulated as follows. To the mixture N44 are added 100 ppm of the stabiliser H-1-1-1.
  • Example 45 The nematic LC mixture N45 is formulated as follows. To the mixture N45 are added 150 ppm of the stabiliser ST-3a-1.
  • Example 46 The nematic LC mixture N46 is formulated as follows.
  • Example 47 The nematic LC mixture N47 is formulated as follows. To the mixture N47 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 48 The nematic LC mixture N48 is formulated as follows. wherein CLOY-(c5)1-O2 is To the mixture N48 are added 100 ppm of the stabiliser ST-8-1.
  • Example 49 The nematic LC mixture N49 is formulated as follows.
  • Example 50 The nematic LC mixture N50 is formulated as follows. To the mixture N50 are added 50 ppm of the stabiliser ST-12. Example 51 The nematic LC mixture N51 is formulated as follows.
  • Example 52 The nematic LC mixture N52 is formulated as follows. To the mixture N52 are added 150 ppm of the stabiliser ST-3a-1.
  • Example 53 The nematic LC mixture N53 is formulated as follows. To the mixture N53 are added 150 ppm of the stabiliser ST-3b-1.
  • Example 54 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-171 and 100 ppm of the stabiliser ST-3a-1 to the mixture of Example 1A.
  • Example 55 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-171 and 100 ppm of the stabiliser ST-3a-1 to the mixture of Example 2.
  • Example 56 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-1 and 100 ppm of the stabiliser ST-3b-1 to the mixture of Example 3.
  • Example 57 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-35 and 50 ppm of the stabiliser H-1-1-1 to the mixture of Example 4.
  • Example 58 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-120 and 150 ppm of the stabiliser ST-9-1 to the mixture of Example 5.
  • Example 59 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-142 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 6.
  • Example 60 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-143 and 150 ppm of the stabiliser ST-3a-1 to the mixture of Example 7.
  • Example 61 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-172 and 50 ppm of the stabiliser H-2-1-1 to the mixture of Example 8.
  • Example 62 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-159 and 50 ppm of the stabiliser H-2-1-1 to the mixture of Example 9.
  • Example 63 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-145 to the mixture of Example 10.
  • Example 64 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-156 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 11.
  • Example 65 A polymerizable mixture is prepared by adding 0.35% of the polymerizable compound RM-162 and 50 ppm of the stabiliser H-2-1-1 to the mixture of Example 12.
  • Example 66 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-58 and 150 ppm of the stabiliser ST-3b-1 to the mixture of Example 13.
  • Example 67 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-160 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 14.
  • Example 68 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-163 and 100 ppm of the stabiliser ST-9-1 to the mixture of Example 15.
  • Example 69 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-64 and 150 ppm of the stabiliser ST-3b-1 to the mixture of Example 16.
  • Example 70 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound a69 and 100 ppm of the stabiliser ST-8-1 to the mixture of Example 17.
  • Example 71 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-157 and 150 ppm of the stabiliser H-2-1-1 to the mixture of Example 18.
  • Example 75 A polymerizable mixture is prepared by adding 0.1% of the polymerizable compound RM-120, 0.3% of the polymerizable compound RM-1 and 150 ppm of the stabiliser H-1- 1-1 to the mixture of Example 22.
  • Example 76 A polymerizable mixture is prepared by adding 0.1% of the polymerizable compound RM-143, 0.3% of the polymerizable compound RM-1 and 150 ppm of the stabiliser ST- 3a-1 to the mixture of Example 23.
  • Example 77 A polymerizable mixture is prepared by adding 0.2% of the polymerizable compound RM-171, 0.2% of the polymerizable compound RM-120 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 24.
  • Example 78 The nematic LC mixture N78 is formulated as follows. To the mixture N78 are added 100 ppm of the stabiliser H-1-1-1.
  • Example 79 The nematic LC mixture N79 is formulated as follows.
  • Example 80 The nematic LC mixture N80 is formulated as follows. To the mixture N80 are added 150 ppm of the stabiliser ST-3b-1.
  • Example 81 The nematic LC mixture N81 is formulated as follows.
  • Example 82 The nematic LC mixture N82 is formulated as follows. To the mixture N82 are added 100 ppm of the stabiliser ST-8-1.
  • Example 83 The nematic LC mixture N83 is formulated as follows. To the mixture N83 are added 50 ppm of the stabiliser ST-9-1.
  • Example 84 The nematic LC mixture N84 is formulated as follows. To the mixture N84 are added 50 ppm of the stabiliser ST-12.
  • Example 85 The nematic LC mixture N85 is formulated as follows. To the mixture N85 are added 100 ppm of the stabiliser H-1-1-1.
  • Example 86 The nematic LC mixture N86 is formulated as follows.
  • Example 87 The nematic LC mixture N87 is formulated as follows. To the mixture N87 are added 150 ppm of the stabiliser ST-3b-1.
  • Example 88 The nematic LC mixture N88 is formulated as follows. To the mixture N88 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 89 The nematic LC mixture N89 is formulated as follows. To the mixture N89 are added 100 ppm of the stabiliser ST-8-1.
  • Example 90 The nematic LC mixture N90 is formulated as follows. To the mixture N90 are added 50 ppm of the stabiliser ST-9-1.
  • Example 91 The nematic LC mixture N91 is formulated as follows.
  • Example 92 The nematic LC mixture N92 is formulated as follows. To the mixture N92 are added 100 ppm of the stabiliser H-1-1-1. Example 93 The nematic LC mixture N93 is formulated as follows.
  • Example 94 The nematic LC mixture N94 is formulated as follows. To the mixture N94 are added 150 ppm of the stabiliser ST-3b-1. Example 95 The nematic LC mixture N95 is formulated as follows.
  • Example 96 The nematic LC mixture N96 is formulated as follows. To the mixture N96 are added 100 ppm of the stabiliser ST-8-1.
  • Example 97 The nematic LC mixture N97 is formulated as follows.
  • Example 98 The nematic LC mixture N98 is formulated as follows. To the mixture N98 are added 50 ppm of the stabiliser ST-12. Example 99 The nematic LC mixture N99 is formulated as follows.
  • Example 100 The nematic LC mixture N100 is formulated as follows. To the mixture N100 are added 150 ppm of the stabiliser ST-3a-1.
  • Example 101 The nematic LC mixture N101 is formulated as follows. To the mixture N101 are added 150 ppm of the stabiliser ST-3b-1.
  • Example 102 The nematic LC mixture N102 is formulated as follows. To the mixture N102 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 103 The nematic LC mixture N103 is formulated as follows. To the mixture N103 are added 100 ppm of the stabiliser ST-8-1.
  • Example 104 The nematic LC mixture N104 is formulated as follows.
  • Example 105 The nematic LC mixture N105 is formulated as follows. wherein CCP-1V2-1 is To the mixture N105 are added 50 ppm of the stabiliser ST-12.
  • Example 106 The nematic LC mixture N106 is formulated as follows.
  • Example 107 The nematic LC mixture N107 is formulated as follows. wherein PYP-2-1(c3) is To the mixture N107 are added 150 ppm of the stabiliser ST-3a-1.
  • Example 108 The nematic LC mixture N108 is formulated as follows. To the mixture N108 are added 150 ppm of the stabiliser ST-3b-1.
  • Example 109 The nematic LC mixture N109 is formulated as follows. To the mixture N109 are added 50 ppm of the stabiliser H-2-1-1.
  • Example 110 The nematic LC mixture N110 is formulated as follows.
  • Example 111 The nematic LC mixture N111 is formulated as follows. To the mixture N111 are added 50 ppm of the stabiliser ST-9-1.
  • Example 112 The nematic LC mixture N112 is formulated as follows. To the mixture N112 are added 50 ppm of the stabiliser ST-12.
  • Example 113 The nematic LC mixture N113 is formulated as follows. To the mixture N113 are added 100 ppm of the stabiliser H-1-1-1.
  • Example 114 The nematic LC mixture N114 is formulated as follows. To the mixture N114 are added 150 ppm of the stabiliser ST-3a-1.
  • Example 115 The nematic LC mixture N115 is formulated as follows. To the mixture N115 are added 150 ppm of the stabiliser ST-3b-1.

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Abstract

The present invention relates to a liquid-crystal (LC) material based on a mixture of polar compounds, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the fringe-field switching mode, to an LC display of the fringe-field switching mode comprising the LC medium, especially an energy- saving LC display and to a process of manufacturing the LC display.

Description

Liquid-Crystal Medium The present invention relates to a liquid-crystal (LC) medium based on a mixture of polar compounds, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the fringe-field switching mode, to an LC display of the fringe-field switching mode comprising the LC medium, especially an energy-saving LC display, to a process of preparing the LC medium, and to a process of manufacturing the LC display. One of the liquid-crystal display (LCD) modes used at present is the TN (“twisted nematic”) mode. However, TN LCDs have the disadvantage of a strong viewing-angle dependence of the contrast. Therefore, so-called FFS (“fringe-field switching”) displays have been reported (see, inter alia, S.H. Jung et al., Jpn. J. Appl. Phys., Volume 43, No.3, 2004, 1028), which contain two electrodes on the same substrate, one of which is structured in a comb-shaped manner and the other is unstructured. A strong, so-called "fringe field" is thereby generated, i.e. a strong electric field close to the edge of the electrodes, and, throughout the cell, an electric field which has both a strong vertical component and also a strong horizontal component. FFS displays have a low viewing-angle dependence of the contrast. FFS displays usually contain an LC medium with positive dielectric anisotropy, and an alignment layer, usually of polyimide, which provides planar alignment to the molecules of the LC medium. FFS displays can be operated as active-matrix or passive-matrix displays. In the case of active-matrix displays, individual pixels are usually addressed by integrated, non-linear active elements, such as, for example, transistors (for example thin-film transistors ("TFTs")), while in the case of passive-matrix displays, individual pixels are usually addressed by the multiplex method, as known from the prior art. Furthermore, a new type of FFS displays (known as "Ultra Brightness FFS (UB-FFS)" mode displays) has been disclosed (see S.H. Lee et al., Appl. Phys. Lett.73(20), 1998, 2882-2883 and S.H. Lee et al., Liquid Crystals 39(9), 2012, 1141-1148), which have similar electrode design and layer thickness as FFS displays, but comprise a layer of an LC medium with negative dielectric anisotropy instead of an LC medium with positive dielectric anisotropy. The LC medium with negative dielectric anisotropy shows a more favourable director orientation that has less tilt and more twist orientation compared to the LC medium with positive dielectric anisotropy, as a result of which these displays have a higher transmission. The displays further comprise an alignment layer, preferably of polyimide provided on at least one of the substrates that is in contact with the LC medium and induces planar alignment of the LC molecules of the LC medium. These displays require an LC medium with high reliability. In addition, so-called VA (“vertically aligned”) displays are known which have a broad viewing angle and fast response times. The LC cell of a VA display contains a layer of an LC medium between two transparent electrodes, where the LC medium usually has a negative value of the dielectric anisotropy ( ^ ^). In the switched-off state, the molecules of the LC layer are aligned perpendicular to the electrode surfaces (homeotropically) or have a tilted homeotropic alignment. On application of a voltage to the two electrodes, a realign- ment of the LC molecules parallel to the electrode surfaces takes place. Also known are so-called IPS (“in-plane switching”) displays, which contain an LC layer between two substrates with planar orientation, where the two electrodes are arranged on only one of the two substrates and preferably have interdigitated, comb-shaped structures. On application of a voltage to the electrodes an electric field with a significant component parallel to the LC layer is generated between them. This causes realignment of the LC molecules in the layer plane. In VA displays of the more recent type, uniform alignment of the LC molecules is restricted to a plurality of relatively small domains within the LC cell. Disclinations may exist between these domains, also known as tilt domains. VA displays having tilt domains have, compared with conventional VA displays, a greater viewing-angle independence of the contrast and the grey shades. In addition, displays of this type are simpler to produce since additional treatment of the electrode surface for uniform alignment of the molecules in the switched-on state, such as, for example, by rubbing, is no longer necessary. Instead, the preferential direction of the tilt or pretilt angle is controlled by a special design of the electrodes. However, the use of LC media with negative dielectric anisotropy in VA or FFS displays has also several drawbacks. For example, they have a significantly lower reliability compared to LC media with positive dielectric anisotropy. The term "reliability" as used hereinafter means the quality of the performance of the display during time and with different stress loads, such as light load, temperature, humidity, or voltage which cause display defects such as image sticking (area and line image sticking), mura, yogore etc. and which are known to the skilled person in the field of LC displays. As a standard parameter for categorising the reliability usually the voltage holding ration (VHR) value is used, which is a measure for maintaining a constant electrical voltage in a test display. The higher the VHR value, the better the reliability of the LC medium. The reduced reliability of an LC medium with negative dielectric anisotropy in a VA or FFS display can be explained by an interaction of the LC molecules with the polyimide of the alignment layer, as a result of which ions are extracted from the polyimide alignment layer, and wherein LC molecules with negative dielectric anisotropy do more effectively extract such ions. This results in new requirements for LC media to be used in VA or FFS displays. In particular, the LC medium has to show a high reliability and a high VHR value after UV exposure. Further requirements are a high specific resistance, a large working- temperature range, short response times even at low temperatures, a low threshold voltage, a multiplicity of grey levels, high contrast and a broad viewing angle, and reduced image sticking. Thus, in displays known from prior art often the undesired effect of so-called "image sticking" or "image burn" is observed, wherein the image produced in the LC display by temporary addressing of individual pixels still remains visible even after the electric field in these pixels has been switched off, or after other pixels have been addressed. This "image sticking" can occur on the one hand if LC media having a low VHR are used. The UV component of daylight or the backlight can cause undesired decomposition reactions of the LC molecules therein and thus initiate the production of ionic or free- radical impurities. These may accumulate, in particular, at the electrodes or the alignment layers, where they may reduce the effective applied voltage. It is therefore an object of the present invention to provide improved LC media for use in FFS-, VA-, or IPS- displays, which do not exhibit the disadvantages described above or only do so to a small extent and have improved properties. A further object of the invention is to provide FFS-, VA-, and IPS- displays with high contrast ratio, good transmission, high reliability, a VHR value especially after backlight exposure, a high specific resistance, a large working-temperature range, short response times even at low temperatures, a low threshold voltage, a multiplicity of grey levels, high contrast and a broad viewing angle, and reduced image sticking. The contrast ratio is defined as the ratio of the luminance of the brightest shade (white) to that of the darkest shade (black) that the system is capable of producing, i.e., the transmittane (white level) to the scattering parameter (dark level). The contrast ratio can be significantly improved by the lower scattering parameter (high Kavg). Therefore, a LC mixture having high Kavg is very effective to achieve a high contrast ratio display. A further object of the present invention is to provide LC mixtures with a favourably high average elastic constant Kavg, which contributes to a high contrast ratio. It was found that one or more of these objects could be achieved by providing an LC medium as disclosed and claimed hereinafter. The invention thus relates to an LC medium comprising one or more compounds of formula I in which R11 and R12 straight chain, branched or cyclic alkyl or alkoxy radical having 1 to 12 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH-, -C ≡C-, in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl, preferably alkyl having 1 to 6 C atoms, more preferably R12 denotes an alkoxy radical; A1 and A2 a group selected from the following formulae preferably from formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably from formulae A1, A2, A3, A4, A6, A9 and A10, Z1 and Z2 independently of one another, identically or differently, denotes a single bond, -CH2O-, -(CO)O-, -CF2O-, -CH2CH2CF2O-, -CF2CF2-, -CH2CF2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CH=CF-, -CF=CF- or -C ^C-, where asymmetrical bridges may be oriented to both sides, L1, L2, L3 and L4 F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F or Cl, very preferably F, Y H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H, LC CH3 or OCH3, preferably CH3, a1 denotes 0; 1, 2 or 3, a2 denotes 0, 1, or 2. In a preferred embodiment the LC medium according to the invention, comprises one or more are compounds of formula I, wherein R11 denotes straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms, R12 denotes straight-chain alkoxy having 1 to 7 C atoms, A1 denotes cyclohexane, Z1 denotes a single bond, a1 denotes 1 or 2 and a2 denotes 0. The compounds of the formula I (see WO 92/09576) can be synthesized using the method as described by V. Reiffenrath et al. in Angew. Chem., 106, No.13, (1994). Preferably, the compounds of the formula I are selected from the group consisting of compounds of the formulae IA, IB, IC, ID, and IE,
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R11, R12 H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted or monosubstituted by F, Cl, CN or CF3 and where, in addition, one or more CH2 groups in these radicals may be replaced by - O-, -S-,-C ^C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O- and/or S-atoms are not linked directly to one another, L1 to L4 F, Cl, CF3 or CHF2, Y H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, particularly preferably H, Z1, Z2 a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O, p 0, 1 or 2, and q 0 or 1. Preferred compounds of the formulae IA, IB, IC and ID are those wherein R12 denotes an alkyl or alkoxy radical having 1 to 15 C atoms, and very preferably denotes (O)CvH2v+1 wherein (O) is an oxygen atom or a single bond and v is 1, 2, 3, 4, 5 or 6. Further preferred compounds of the formulae IA, IB, IC, ID and IE are those wherein R11 or R12 each, independently of one another, denotes or contains a cycloalkyl or cycloalkoxy radical, preferably selected from the group consisting of wherein S1 is C1-12-alkylene or C2-12-alkenylene and S2 is H, C1-12-alkyl or C2-12-alkenyl, and very preferably are selected from the group consisting of Further preferred compounds of the formulae IA, IB, IC, ID and IE are indicated below. In a preferred embodiment the LC medium comprises one or more compounds of the formula IA selected from the group consisting of the following formulae:
in which the index a denotes 1 or 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2- CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IA-2, IA-4, IA-6, IA-8, IA-10, IA-22, IA-23, IA-24, IA-25 and IA-32 to IA-36. Preferably, the LC medium comprises one or more compounds of the formula IA-2 selected from the following subformulae:
Alternatively, preferably in addition to the compounds of the formulae IA-2-1 to IA-2-5, the LC medium comprises one or more compounds of the following formulae:
Further preferably, the LC medium comprises one or more compounds of the formula IA- 6 selected from the following sub-formulae:
Alternatively, preferably in addition to the compounds of the formulae IA-6-1 to IA-6-5, the LC medium comprises one or more compounds of the following formulae:
Preferred LC media additionally comprise one or more compounds of formula IA-0 in which R11 and R12 have one of the meanings given in formula IA above. Preferred compounds of the formula IA-0 are selected from the group consisting of the following subformulae in which, Alkyl and Alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, Alkoxy and Alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms, and O denotes an oxygen atom or a single bond. Alkenyl and Alkenyl* preferably denote CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2- CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred compounds of the formula IA-0 are selected from the group consisting of subformula IA-0-6, in which Alkoxy has the meanings defined above and preferably denotes methoxy, ethoxy, n- propyloxy, n-butyloxy or n-pentyloxy. In another preferred embodiment the LC medium comprises one or more compounds of the formula IB selected from the group consisting of the following formulae:
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2- CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IB-2, IB-6 and IB-8. Preferably, the LC medium comprises one or more compounds of the formula IB-6 selected from the following sub-formulae:
Alternatively, preferably in addition to the compounds of the formulae IB-6-1 to IB-6-5, the LC medium comprises one or more compounds of the following formulae:
In another preferred embodiment the LC medium comprises one or more compounds of the formula IC selected from the formula IC-1, in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, preferably in amounts of 0.5% to 5 % by weight, in particular 1% to 3 % by weight. In another preferred embodiment the LC medium comprises one or more compounds of the formula ID selected from the group consisting of the following formulae,
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, (O) denotes an oxygen atom or a single bond, Y denotes H or CH3 and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2- CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds of the formula ID-1 and/or ID-2. Very preferred compounds of the formula ID are compounds of the formula ID-5 selected from the following subformulae,
wherein v is 1, 2, 3, 4, 5 or 6. In a preferred embodiment, the LC medium comprises one or more compounds of formula ID-5a in which R11, Y and q have the meanings given in formula ID, and R13 is , in which r is 0, 1, 2, 3, 4, 5 or 6 and s is 1, 2 or 3. Preferred compounds of formula IID-5a are selected from the following subformulae:
In a preferred embodiment the LC medium comprises one or more compounds of the formula IE selected from the group consisting of the following formulae: in which the index a denotes 1 or 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2- CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IE-1, IE-2, IE-3, IE-4, IE-5. The proportion of compounds of the formulae IA and/or IB in the mixture as a whole is preferably at least 20 % by weight. The most preferred compounds of the formula I are the following compounds wherein n is 2, 3, 4, or 5, and m is 2, 3, or 4: Particularly preferred LC media according to the invention comprise one or more compounds selected from the formulae IA-2, IA-4, IA-6, IA-8, I-10, IA-22, IA-23, IA-24, IA-25, IB-2, IB-6, IB-8, IC-1, ID-2, ID-5, IE-1, IE-2, IE-3, IE-4, IE-5, or their subformulae. The invention further relates to the use of the LC medium as described above and below in LC displays, preferably in LC displays of the VA, IPS, FFS, UB-FFS or UBplus mode. The invention furthermore relates to a process for preparing an LC medium as described above and below, comprising the steps of mixing one or more compounds of formula I with one or more compounds as described below and optionally with further LC compounds and/or additives. The invention furthermore relates to an LC display comprising an LC medium according to the invention as described above and below, preferably an LC display of the VA, IPS, FFS, UB-FFS or UBplus mode. The invention furthermore relates to a process for manufacturing an LC display as described above and below, comprising the steps of filling or otherwise providing an LC medium as described above and below between the substrates of the display. The LC media according to the present invention allow to achieve one or more of the following advantageous effects: - a favourably high average elastic constant Kavg that equals to (K1+K2+K3)/3, which contributes to a high contrast ratio, - a favourably low ratio of rotational viscosity to the splay elastic constant γ1 / K11, which contributes to improved switching behaviour especially at low driving voltages and is useful to enable energy-saving displays. The LC media according to the present invention show one or more of the following advantageous properties when used in LC displays: - high contrast ratio, - high transmittance, - reduced rotational viscosity, - fast response times, - a low threshold voltage which is useful to enable energy-saving displays. It was surprisingly found that the LC media according to the present invention show a favourable combination of low rotational viscosity and high average elastic constant Kavg. A low rotational viscosity and therefore the low ratio of rotational viscosity to the splay elastic constant ^1 / K11 improves switching behaviour especially at low driving voltages. On the other hand an increased Kavg enables the realisation of a low scattering parameter and thereby a high contrast ratio. Moreover, in terms of reliability the LC media according to the present invention show high VHR values and less or no undesired mura effects such as edge mura. Above and below, denotes a trans-1,4-cyclohexylene ring, and denotes a 1,4-phenylene ring. In a group the single bond shown between the two ring atoms can be attached to any free position of the benzene ring. If in the formulae shown above and below a terminal group like R11,12, R21,22, R31, 32, 33, R41,42, R51,52, R61, R71, RN1,N2, R81,82, R91,92,93, RL1,L2, RQ, RR1 ,R2, or L denotes an alkyl radical and/or an alkoxy radical, this may be straight-chain or branched. It is preferably straight-chain, has 2, 3, 4, 5, 6 or 7 C atoms and accordingly preferably denotes ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexyloxy or heptyloxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy. If one of the aforementioned terminal groups denotes an alkyl radical wherein one or more CH2 groups are replaced by S, this may be straight-chain or branched. It is preferably straight-chain, has 1, 2, 3, 4, 5, 6 or 7 C atoms and accordingly preferably denotes thiomethyl, thioethyl, thiopropyl, thiobutyl, thiopentyl, thiohexyl or thioheptyl. 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, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl. If one of the aforementioned terminal groups denotes an alkoxy or oxaalkyl group it may also contain one or more additional oxygen atoms, provided that oxygen atoms are not linked directly to one another. If one of the aforementioned terminal groups denotes an alkyl radical in which one CH2 group has been replaced by -CH=CH-, this may be straight-chain or branched. It is preferably straight-chain and has 2 to 10 C atoms. Accordingly, it denotes, in particular, vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl. If one of the aforementioned terminal groups denotes an alkyl or alkenyl radical which is at least monosubstituted by halogen, this radical is preferably straight-chain, and halogen is preferably F or Cl. In the case of polysubstitution, halogen is preferably F. The resultant radicals also include perfluorinated radicals. In the case of monosubstitution, the fluorine or chlorine substituent may be in any desired position, but is preferably in the ^-position. In another preferred embodiment, one or more of the aforementioned terminal groups, like R11,12, R21,22, R31, 32, 33, R41,42, R51,52, R61, R71, RN1,N2, R81,82, R91,92,93, RL1,L2, RQ, RR1,R2, or L are selected from the group consisting of -S1-F, -O-S1-F, -O-S1-O-S2, wherein S1 is C1-12-alkylene or C2-12-alkenylene and S2 is H, C1-12-alkyl or C2-12-alkenyl, and very preferably are selected from the group consisting of Halogen is preferably F or Cl, very preferably F. The group -CR0=CR00- is preferably -CH=CH-. -CO-, -C(=O)- and -C(O)- denote a carbonyl group, i.e. . Preferred substituents L, are, for example, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, - SCN, -C(=O)N(Rx)2, -C(=O)Y1, -C(=O)Rx, -N(Rx)2, straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 25 C atoms, in which one or more H atoms may optionally be replaced by F or Cl, optionally substituted silyl having 1 to 20 Si atoms, or optionally substituted aryl having 6 to 25, preferably 6 to 15, C atoms, wherein Rx denotes H, F, Cl, CN, or straight chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by - O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F, Cl, P- or P-Sp-, and Y1 denotes halogen. Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, furthermore phenyl. in which L has one of the meanings indicated above. Further preferred embodiments of the LC medium according to the present invention are listed below, including any combination thereof. Preferably the LC medium further comprises one or more compounds of formula II,
wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings R21 and R22 straight chain, branched or cyclic alkyl or alkoxy having 1 to 20 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR0=CR00-, -C ≡C-, in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F, Cl, CN or CF3, preferably alkyl or alkoxy having 1 to 6 C atoms, R0, R00 H or alkyl having 1 to 12 C atoms, A1 and A2 a group selected from the following formulae
preferably from formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably from formulae A1, A2, A3, A4, A6, A9 and A10, Z1 and Z2 -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, L1, L2, L3 and L4 F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F or Cl, very preferably F, Y H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H, LC CH3 or OCH3, preferably CH3, a1 0, 1 or 2, a2 0 or 1. Preferably the LC medium comprises one or more compounds of formula II selected from the group consisting of compounds of the formulae IIA, IIB, IIC, IID and IIE,
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R21, R22 H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted or monosubstituted by F, Cl, CN or CF3 and where, in addi- tion, one or more CH2 groups in these radicals may be replaced by -O-, - S-,-C ≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O- and/or S-atoms are not linked directly to one another, L1 to L4 F, Cl, CF3 or CHF2, Y H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, particularly preferably H, Z1, Z2 a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, - COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O, p 0, 1 or 2, and q 0 or 1. Preferred compounds of the formulae IIA, IIB, IIC, IID and IIE are those wherein R22 denotes an alkyl or alkoxy radical having up to 15 C atoms, and very preferably denotes (O)CvH2v+1, wherein (O) is an oxygen atom or a single bond and v is 1, 2, 3, 4, 5 or 6. Further preferred compounds of the formulae IIA, IIB, IIC, IID and IIE are those wherein R21 or R22 each, independently of one another, denotes or contains cycloalkyl or cycloalkoxy radical, preferably selected from the group consisting of wherein S1 is C1-12-alkylene or C2-12-alkenylene and S2 is H, C1-12-alkyl or C2-12-alkenyl, and very preferably are selected from the group consisting of Further preferred compounds of the formulae IIA, IIB, IIC, IID and IIE are indicated below. In a preferred embodiment the LC medium comprises one or more compounds of the formula IIA selected from the group consisting of the following formulae:
in which the index a denotes 1 or 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2- CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IIA-2, IIA-8, IIA-10, IIA-16, IIA-18, IIA-40, IIA-41, IIA-42 and IIA-43. Preferably, the LC medium comprises one or more compounds of the formula IIA-2 selected from the following subformulae:
Alternatively, preferably in addition to the compounds of the formulae IIA-2-1 to IIA-2-5, the LC medium comprises one or more compounds of the following formulae:
Further preferably, the LC medium comprises one or more compounds of the formula IIA-10 selected from the following sub-formulae: Alternatively, preferably in addition to the compounds of the formulae IIA-10-1 to IIA-10- 5, the LC medium comprises one or more compounds of the following formulae:
Preferred LC media additionally comprise one or more compounds of formula IIA-Y in which R21 and R22 have one of the meanings given in formula IIA above, and L1 and L2, identically or differently, denote F or Cl. Preferred compounds of the formula IIA-Y are selected from the group consisting of the following subformulae in which, Alkyl and Alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl* each, independently of one another, denote a straight- chain alkenyl radical having 2-6 C atoms, and O denotes an oxygen atom or a single bond. Alkenyl and Alkenyl* preferably denote CH2=CH-, CH2=CHCH2CH2-, CH3- CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3- CH=CH-(CH2)2-. Particularly preferred compounds of the formula IIA-Y are selected from the group consisting of following subformulae: in which Alkoxy and Alkoxy* have the meanings defined above and preferably denote methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy. In another preferred embodiment the LC medium comprises one or more compounds of the formula IIB selected from the group consisting of formulae IIB-1 to IIB-30,
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2- CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IIB-2, IIB-10 and IIB-16. Preferably, the LC medium comprises one or more compounds of the formula IIB-10 selected from the following sub-formulae:
Alternatively, preferably in addition to the compounds of the formulae IIB-10-1 to IIB-10- 5, the LC medium comprises one or more compounds of the formulae IIB-10a-1 to IIB- 10a-5:
In another preferred embodiment the LC medium comprises one or more compounds of the formula IIC selected from the formula IIC-1, in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, preferably in amounts of 0.5% to 5 % by weight, in particular 1% to 3 % by weight. In another preferred embodiment the LC medium comprises one or more compounds of the formula IID selected from the group consisting of the following formulae, in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2- CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds of the formula IID-1 and/or IID-4. Very preferred compounds of the formula IID are selected from the following subformulae of IID-1,
wherein v is 1, 2, 3, 4, 5 or 6. Very preferred compounds of the formula IID are selected from the following subformulae of IID-4,
wherein v is 1, 2, 3, 4, 5 or 6. Very preferred compounds of the formula IID are selected from the following subformulae of IID-14,
wherein v is 1, 2, 3, 4, 5 or 6. In a preferred embodiment, the LC medium comprises one or more compounds of formula IID-14a in which R21, Y and q have the meanings given in formula IID, and R23 is , in which r is 0, 1, 2, 3, 4, 5 or 6 and s is 1, 2 or 3. Preferred compounds of formula IID-14a are the compounds IID-14a-1 to IID-14a-14: Very preferred compounds of the formula IID are selected from the following subformulae of IID-17, wherein v is 1, 2, 3, 4, 5 or 6. In a preferred embodiment the LC medium comprises one or more compounds of the formula IIE selected from the group consisting of the following formulae: in which the index a denotes 1 or 2, alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and (O) denotes an oxygen atom or a single bond, and alkenyl preferably denotes CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2- CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-. Particularly preferred LC media according to the invention comprise one or more compounds selected from the group consisting of formulae IIE-2, IIE-8, IIE-10, IIE-16, IIE-18, IIE-37, IIE-38, IIE-39 and IIE-40. Preferably, the LC medium comprises one or more compounds of the formula IIE-2 selected from the following sub-formulae: Preferably, the LC medium comprises one or more compounds of the formula IIE-10 selected from the following sub-formulae: Particularly preferred LC media according to the invention comprise one or more compounds selected from the formulae IIA-2, IIA-8, IIA-10, IIA-16, IIA-18, IIA-40, IIA-41, IIA-42, IIA-43, IIB-2, IIB-10, IIB-16, IIC-1, IID-4, IID-10, IIE-2, IIE-8, IIE-10, IIE-16, IIE-18, IIE-37, IIE-38, IIE-39, and IIE-40 or their subformulae. The proportion of compounds of the formulae IIA and/or IIB in the mixture as a whole is preferably at least 20 % by weight. In another preferred embodiment the LC medium comprises one or more compounds of formula III and/or one or more compounds of formula 11 IA in which
R31 and R32 each, independently of one another, denote H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may be replaced by -O-, -S-,
-C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO- in such a way that O atoms are not linked directly to one another,
Y1, Y2 H, F, Cl, CF3, CHF2, CH3 or OCH3, preferably H, CH3 or OCH3, very preferably H,
A3 on each occurrence, independently of one another, denotes a) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4- tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, n denotes 0, 1 or 2, preferably 0 or 1, Z3 on each occurrence independently of one another denotes -CO-O-, -O-CO-, -CF2O- , -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2- -, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C ≡C- or a single bond, and L31 and L32 each, independently of one another, denote F, Cl, CF3 or CHF2, preferably H or F, most preferably F. In the compounds of formula III R31 and R32 are preferably selected from straight-chain alkyl or alkoxy with 1 to 12, preferably 1 to 7 C atoms, straight-chain alkenyl with 2 to 12, preferably 2 to 7 C atoms and cyclic alkyl or alkoxy with 3 to 12, preferably 3 to 8 C atoms. In a preferred embodiment of the present invention the LC medium comprises one or more compounds of formula III selected from the subformulae III-1 to III-6:
in which the occurring groups have the same meanings as given under formula III above and preferably R31 and R32 each, independently of one another, denote an alkyl, alkenyl or alkoxy radical having up to 15 C atoms, preferably having 1 to 7 C atoms, more preferably one or both of them denote an alkoxy radical; or cyclic alkyl having 3 to 6 C atoms, R33 denotes alkyl or alkenyl having up to 7 C atoms or a group Cy-CnH2n+1-, m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, which is optionally substituted with alkyl or alkenyl each having up to 3 C atoms, or with halogen or CN, and preferably denotes cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, (O) denotes O or a single bond, and L31 and L32 each, independently of one another, denote F or Cl, preferably both denote F. In another preferred embodiment the LC medium comprises one or more compounds of the formula III-1 selected from the group of compounds of formulae III-1-1 to III-1-10, preferably of formula III-1-1,
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms, alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, and L31 and L32 each, independently of one another, denote F or Cl, preferably both F. Very preferred compounds of formula III-1-1 are selected from the group consisting of the following subformulae,
in which alkoxy denotes a straight-chain alkoxy radical having 1, 2, 3 or 4 C atoms. Very preferred compounds of the formula III-2 are the following,
in which alkoxy denotes a straight-chain alkoxy radical having 1-6 C atoms, preferably ethoxy, propoxy, butoxy or pentoxy, very preferably ethoxy or propoxy. Very preferred compounds of formula III-6 are selected from the group consisting of the following formulae, in which R32 denotes alkyl having 1 to 7 C-atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl or alternatively – (CH2)nF in which n is 2,3,4, or 5, preferably C2H4F. Preferred compounds of formula III is III-1-1-3, III-1-1-4, III-1-1-5 as well as III-6-2, and the most preferred are compounds B(S)-2O-O4, B(S)-2O-O5, B(S)-2O-O6, and COB(S)-2- O4. In a preferred embodiment of the present invention the LC medium comprises one or more compounds of formula IIIA selected from the subformulae IIIA-1 to IIIA-6: in which the occurring groups have the same meanings as given under formula III above and preferably R31 and R32 each, independently of one another, denote an alkyl, alkenyl or alkoxy radical having up to 15 C atoms, preferably having 1 to 7 C atoms, more preferably one or both of them denote an alkoxy radical; or cyclic alkyl having 3 to 6 C atoms, R33 denotes alkyl or alkenyl having up to 7 C atoms or a group Cy-CnH2n+1-, m and n are, identically or differently, 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy denotes a cycloaliphatic group having 3, 4 or 5 ring atoms, which is optionally substituted with alkyl or alkenyl each having up to 3 C atoms, or with halogen or CN, and preferably denotes cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl, (O) denotes O or a single bond, and L31 and L32 each, independently of one another, denote F or Cl, preferably both denote F. Preferred compounds of formula IIIA are those of formula IIIA-1: in which the occurring groups have the same meanings as given under formula IIIA above and preferably R31 and R32 each, independently of one another, an alkyl, alkenyl or alkoxy radical having up to 15 C atoms, preferably having 1 to 7 C atoms, more preferably one or both of them denote an alkoxy radical and L31 and L32 each, independently of one another, denote F or Cl, preferably both denote F. In another preferred embodiment the LC medium comprises one or more compounds of the formula IIIA-1 selected from the group of compounds of formulae IIIA-1-1 to IIIA-1- 10, preferably of formula IIIA-1-6,
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6 C atoms, alkoxy and alkoxy* each, independently of one another, denote a straight-chain alkoxy radical having 1-6 C atoms, and L31 and L32 each, independently of one another, denote F or Cl, preferably both F. In a preferred embodiment, the LC medium comprises one or more compounds of the formula IV, in which R41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms where, in addition, one or more CH2 groups may be replaced by or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2, 3, 4 or 5 C atoms, and R42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, both preferably having 2 to 5 C atoms, or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably a vinyl radical or a 1-propenyl radical and in particular a vinyl radical. The compounds of the formula IV are preferably selected from the group of the compounds of the formulae IV-1 to IV-4, in which alkyl and alkyl’, independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, alkenyl denotes an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms, alkenyl’ denotes an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms. Preferably, the LC medium comprises one or more compounds selected from the compounds of the formulae IV-1-1 to IV-1-6:
Very preferably, the LC medium according to the invention comprises one or more compounds of the formulae IV-2-1 and/or IV-2-2 Very preferably, the LC medium according to the invention comprises a compound of formula IV-3, in particular selected from the compounds of the following subformulae: The LC medium according to the invention preferably comprises one or more compounds CC-n-V and/or CC-n-Vm, in particular CC-3-V, CC-4-V, CC-3-V1 and/or CC-4-V1, preferably in a total concentration in the range of from 15 to 60 %, preferably from 18 to 52 %. CC-3-V is preferably used in concentrations of 5-50 %, in particular 6-45 %. In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula IV-3 selected from the compounds of the following subformulae: in which alkyl denotes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or n-pentyl. Very preferably, the LC medium according to the invention comprises a compound of formula IV-4, in particular selected from the compounds of the following formulae: In another preferred embodiment the LC medium comprises one or more compounds of formula IV-4 and its subformulae in which one or both of "alkenyl" and "alkenyl' " denote in which m is 0, 1 or 2, and n is 0, 1 or 2, very preferably selected from compounds of formulae IV-4-3 to IV-4-6. Very preferably, the LC medium according to the invention comprises one or more compounds of the formula IV-1 or its subformulae and/or one or more compounds of the formula IV-3 or its subformulae and/or one or more compounds of the formula IV-4 or its subformulae, where the total concentration of these compounds of the formula IV-1 is in the range from 1% to 30%. The LC medium according to the invention preferably additionally comprises one or more compounds of the formula IVa, in which R41 and R42 each, independently of one another, denote a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy radical having up to 12 C atoms, Z4 denotes a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8- or -CF=CF-. Preferred compounds of the formula IVa are indicated below: in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms. The LC medium according to the invention preferably comprises at least one compound of the formula IVa-1and/or formula IVa-2. The proportion of compounds of the formula IVa in the mixture as a whole is preferably at least 5 % by weight Preferably, the LC medium comprises one or more compounds of formula IVb-1 to IVb- 3 in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2 to 6 C atoms. The proportion of the compounds of the formulae IV-1 to IV-3 in the mixture as a whole is preferably at least 3 % by weight, in particular ≥ 5 % by weight. Of the compounds of the formulae IVb-1 to IVb-3, the compounds of the formula IVb-2 are particularly preferred. Particularly preferred compounds of the formulae IV-1 to IV-3 are selected from the group consisting of the following formulae in which alkyl* denotes an alkyl radical having 1 to 6 C atoms and preferably denotes n- propyl. The LC medium according to the invention particularly preferably comprises one or more compounds of the formulae IVb-1-1 and/or IVb-2-3. In another preferred embodiment, the LC medium according to the invention comprises one or more compounds of formula V in which R51 and R52 independently of one another, denote H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may be replaced by -O-, -S-,-C ≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and preferably denote alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy having 1 to 6 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably alkenyloxy, identically or differently, denote in which preferably denotes Z51 , Z52 each, independently of one another, denote -CH2-CH2-, -CH2-O- ,-CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH2-CH2-, -CH2- O- or a single bond and particularly preferably a single bond, and n is 1 or 2. The compounds of formula V are preferably selected from the compounds of the formulae V-1 to V-17:
in which R51 and R52 have the meanings as indicated above. R51 and R52 preferably each, independently of one another, denote straight-chain alkyl or alkenyl. Preferred LC media comprise one or more compounds of the formulae V-1, V-3, V-4, V- 6, V-7, V-10, V-11, V-12, V-14, V-15, and/or V-16. LC media according to the invention very particularly preferably comprise the compounds of the formula V-10 and/or IV-1, in particular in amounts of 5 to 30 %. Preferred compounds of the formulae V-10 are indicated below:
The LC medium according to the invention particularly preferably comprises the tricyclic compounds of the formula V-10a and/or of the formula V-10b in combination with one or more bicyclic compounds of the formulae IV-1 The total proportion of the compounds of the formulae V-10a and/or V-10b in combination with one or more compounds selected from the bicyclohexyl compounds of the formula IV-1 is 5 to 40 %, very particularly preferably 15 to 35 %. Particularly preferred LC media comprise the compounds V-10a and/or IV-1-1 The compounds V-10a and IV-1-1 are preferably present in the mixture in a concentration of 5 to 30 %, very preferably 10 to 25 %, based on the mixture as a whole. Preferred LC media comprise at least one compound selected from the group of the compounds
in which R51, R52, R41 and R42 have the meanings indicated above. Preferably in the compounds V-6, V-7 and IV, R51 and R41 denotes alkyl or alkenyl having 1 to 6 or 2 to 6 C atoms, respectively, and R52 and R42 denotes alkenyl having 2 to 6 C atoms. Preferably in the compounds V-14, R51 denotes alkyl or alkenyl having 1 to 6 or 2 to 6 C atoms and R52 denotes alkyl having 1 to 6 C atoms, or alkoxy having 2 to 6 C atoms. In another preferred embodiment the LC medium according to the invention comprises one or more compounds of the formula V-7, preferably selected from the compounds of the formulae V-7a to V-7e: in which alkyl denotes an alkyl group having 1 to 7 C atoms, alkenyl denotes an alkenyl group having 2 to 7 C atoms, and cycloalkyl denotes a cyclic alkyl group having 3 to 12 C atoms, preferably cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylalkyl, cyclobutylalkyl or cyclopentylalkyl. Very preferred compounds of the formulae V-7a to V-7e are selected from the compounds of the following subformulae:
in which alkyl denotes ethyl, n-propyl, n-butyl or n-pentyl, preferably n-propyl. Further preferred are compounds of formula V, wherein R51 and R52 independently of one another denote straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms. In a preferred embodiment of the present invention the LC medium additionally comprises one or more compounds of the formulae VI-1 to VI-25, in which R61 denotes a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms, cycloalkyl having 3 to 6 C atoms, (O) denotes -O- or a single bond, X denotes F, Cl, OCF3 or OCHF2, Lx denotes H or F, m is 0, 1, 2, 3, 4, 5 or 6 and n is 0, 1, 2, 3 or 4. R61 preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentoxy. X preferably denotes F or OCH3, very preferably F. The LC medium according to the invention preferably comprises the terphenyls of the formulae VI-1 to VI-25 in amounts of 2 to 30 % by weight, in particular 5 to 20 % by weight. Particular preference is given to compounds of the formulae VI-1, VI-2, VI-4, VI-20, VI- 21, and VI-22 wherein X denotes F. In these compounds, R61 preferably denotes alkyl, furthermore alkoxy, each having 1 to 5 C atoms. In the compounds of the formula VI- 20, R61 preferably denotes alkyl or alkenyl, in particular alkyl. In the compounds of the formula VI-21, R61 preferably denotes alkyl. In the compounds of the formulae VI-22 to VI-25, X preferably denotes F. The terphenyls of formula VI-1 to VI-25 are preferably employed in the LC media according to the invention if the Δn value of the mixture is to be ≥ 0.1. Preferred LC media comprise 2 to 20 % by weight of one or more terphenyl compounds selected from the group of the compounds of formulae VI-1 to VI-25. In another preferred embodiment of the present invention the LC medium additionally comprises one or more compounds of the formulae VII-1 to VII-9 in which R71 each, independently of one another, have one of the meanings indicated for R21 in formula IIA, and w and x each, independently of one another, denote 1 to 6. Particular preference is given to LC media comprising at least one compound of the formula VII-9. LC medium comprising one or more substances which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, the compounds of the formulae N-1 to N-5, in which RN1 and RN2 each, independently of one another, have the meanings indicated for R21, preferably denote straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and ZN1 and ZN2 each, independently of one another, denote -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond. LC medium comprising one or more compounds selected from the group of the difluorodibenzochroman compounds of the formula BC, chromans of the formula CR, and fluorinated phenanthrenes of the formulae PH-1 and PH-2,
in which R81 and R82 each, independently of one another, have the meaning of R21 and c is 0, 1 or 2. R81 and R82 preferably, independently of one another, denote alkyl or alkoxy having 1 to 6 C atoms. The LC medium according to the invention preferably comprises the compounds of the formulae BC, CR, PH-1, PH-2 in amounts of 3 to 20 % by weight, in particular in amounts of 3 to 15 % by weight. Particularly preferred compounds of the formulae BC and CR are the compounds BC-1 to BC-7 and CR-1 to CR-5,
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2 to 6 C atoms. Very particular preference is given to an LC medium comprising one, two or three compounds of the formula BC-2, BF-1 and/or BF-2. Particularly preferred compounds of the formula BC the compounds B(A)-2O- O2, Particularly preferred compounds of the formula PH-1 the compounds B(P)-2O- O3 and B(P)-2O-O4,
LC medium comprising one or more indane compounds of the formula In, in which R91, R92, R93 each, independently of one another, denote a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl radical having 1 to 6 C atoms, R92 and R93 may also denote halogen, preferably F, i denotes 0, 1 or 2. Preferred compounds of the formula In are the compounds of the formulae In-1 to In-16 indicated below:
Particular preference is given to the compounds of the formulae In-1, In-2, In-3 and In-4. The compounds of the formula In and the sub-formulae In-1 to In-16 are preferably employed in the LC media according to the invention in concentrations ≥ 5 % by weight, in particular 5 to 30 % by weight and very particularly preferably 5 to 25 % by weight. LC medium comprising one or more compounds of the formulae L-1 to L-8,
in which RL1 and RL2 each, independently of one another, have the meanings indicated for R21 in formula IIA above, alkyl denotes an alkyl radical having 1 to 6 C atoms, and s denotes 1 or 2. The compounds of the formulae L-1 to L8 are preferably employed in concentrations of 5 to 15 % by weight, in particular 5 to 12 % by weight and very particularly preferably 8 to 10 % by weight. LC medium comprising one or more quaterphenyl compounds selected from the following formula: wherein RQ is alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated, XQ is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, LQ1 to LQ6 independently of each other are H or F, with at least one of LQ1 to LQ6 being F. Preferred compounds of formula Q are those wherein RQ denotes straight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl, n-propyl or n-butyl. Preferred compounds of formula Q are those wherein LQ3 and LQ4 are F. Further preferred compounds of formula Q are those wherein LQ3, LQ4 and one or two of LQ1 and LQ2 are F. Preferred compounds of formula Q are those wherein XQ denotes F or OCF3, very preferably F. The compounds of formula Q are preferably selected from the following subformulae wherein RQ has one of the meanings of formula Q or one of its preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl. Especially preferred are compounds of formula Q1, in particular those wherein RQ is n-propyl. Preferably the proportion of compounds of formula Q in the LC medium is from >0 to ≤5% by weight, very preferably from 0.05 to 2% by weight, more preferably from 0.1 to 1% by weight, most preferably from 0.1 to 0.8% by weight. Preferably the LC medium contains 1 to 5, preferably 1 or 2 compounds of formula Q. The addition of quaterphenyl compounds of formula Q to the LC mixture of a polymerizable LC medium enables to reduce ODF mura, whilst maintaining high UV absorption, enabling quick and complete polymerization, enabling strong and quick tilt angle generation, and increasing the UV stability of the LC medium. Besides, the addition of compounds of formula Q, which have positive dielectric anisotropy, to the LC medium with negative dielectric anisotropy allows a better control of the values of the dielectric constants and , and in particular enables to achieve a high value of the dielectric constant while keeping the dielectric anisotropy Δ ε constant, thereby reducing the kick-back voltage and reducing image sticking. The LC medium according to the invention preferably comprises - one or more compounds of formula I or its subformulae in a proportion from 1 to 25%, very preferably from 2 to 22 %, most preferably from 2.5 to 20% by weight; and/or - one or more compounds of formula IIA, IIB, and/or IID, preferably in a total concentration in the range of from 20 to 65%, more preferably from 25 to 60%, particularly preferably from 30 to 55%; wherein formula IIA preferably in a total concentration in the range of 5 to 30%; wherein formula IIB preferably in a total concentration in the range of 1 to 5%; wherein formula IID preferably in a total concentration in the range of 10 to 35%; wherein the total concentration of one or more compounds of formula I and IIA is preferably in the range from 10 to 45%, more preferably from 15 to 30%, most preferably from 17 to 28% by weight; wherein the total concentration of one or more compounds of formula I and IID is preferably in the range from 10 to 50%, more preferably from 15 to 42%, most preferably from 18 to 38% by weight; wherein the total concentration of one or more compounds of formula I and IIA and IID is preferably in the range from 25 to 60%, more preferably from 30 to 55%, most preferably from 35 to 52% by weight; and/or - one or more compounds of formula III, preferably of formula III-1 and/or III-6, very preferably of formula III-1-1 and/or III-6-2, preferably in a total concentration in the range of 1% to 20%, very preferably 3% to 18%; wherein the total concentration of one or more compounds of formula I and formula III is preferably in the range from 8 to 30%, more preferably from 10 to 25%, most preferably from 13 to 22% by weight; wherein the total concentration of one or more compounds of formula I and/or formula IIA, IIB, and/or IID and/or formula III is preferably in the range from 40 to 70%, more preferably from 45 to 65%, most preferably from 50 to 58% by weight; and/or - one or more compounds of formula IV, preferably in a total concentration in the range of 35% to 60%, more preferably 38% to 55%, particularly preferably 40% to 50%; Further preferred embodiments are listed below, where the acronyms used are explained in Table B: - one or more compound A-1 and/or compound A-2, preferably in a proportion from 1 to 25%, very preferably from 2 to 22 %, most preferably from 2.5 to 20% by weight; and/or - Y-nO-Om, CY-n-Om, CCY-n-m, CCY-n-Om, LY-n-Om, CLY-n-Om, CLOY-n-Om, PY- n-Om, and/or CPY-n-Om, in particular Y-4O-O4, CY-3-O2, CCY-3-1,CCY-3-O1, CCY-3- O2, CCY-4-O2, CCY-5-O2, CLY-2-O4, CLY-3-O2, CLY-3-O3, CLY-4-O2, CLY-5-O2, CLOY-3-O2, PY-1-O2, and/or CPY-3-O2, preferably in a total concentration in the range of from 20 to 65%, more preferably from 25 to 60%, particularly preferably from 30 to 55%, based on the mixture as a whole; wherein Y-nO-Om, CY-n-Om, CCY-n-m, and CCY-n-Om preferably in a total concentration in the range of 5 to 30%; wherein PY-n- Om and CPY-n-Om preferably in a total concentration in the range of 1 to 5%; wherein CLY-n-Om and CLOY-n-Om preferably in a total concentration in the range of 10 to 35%; and/or - one or more compounds of B(S)-nO-Om and/or COB(S)-n-Om, in particular B(S)-2O- O4, B(S)-2O-O5, B(S)-2O-O6, and COB(S)-2-O4, preferably in a total concentration in the range of 1% to 20%, very preferably 3% to 18%; and/or - one or more compounds CC-n-m, CC-n-V, CC-n-Vm, CC-nV-Vm, and/or CC-n-Om, in particular CC-2-3, CC-3-4, CC-3-5, CC-3-V, CC-3-V1, CC-4-V1, and/or CC-3-O3, preferably in a total concentration in the range of 35% to 60%, more preferably 38% to 55%, particularly preferably 40% to 50%; and/or - one or more compounds CY-n-Om, in particular CY-3-O4, CY-5-O4 and/or CY-3-O2, preferably in a total concentration in the range of from 5% to 30%, preferably 10% to 20%, based on the mixture as a whole; - one or more compounds PY-n-Om, in particular PY-1-O2, PY-2-O2 and/or PY-3-O2, preferably in a total concentration in the range of from 5% to 40%, preferably 10% to 30%, based on the mixture as a whole; and/or - one or more compounds CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and/or CPY- 5-O2, preferably in concentrations > 5%, in particular 7% to 20%, based on the mixture as a whole, and/or - one or more compounds CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and/or CCY-5-O2, preferably in concentrations > 3%, in particular 5 to 15%, based on the mixture as a whole; and/or - one or more compounds CPY-n-Om and CY-n-Om, preferably in concentrations of 10 to 80%, based on the mixture as a whole, and/or - one or more compounds CPY-n-Om and PY-n-Om, preferably CPY-2-O2 and/or CPY- 3-O2 and PY-3-O2 or PY-1-O2, preferably in concentrations of 5 to 20%, more preferably 10 to 15% to based on the mixture as a whole, and/or - one or more compound(s) selected from the group consisting of CCH-13, CCH-23, CCH-34, CCH-35, CCH-301 and CCH-303, preferably in a total concentration of 3 to 40%, preferably 3 to 25% based on the mixture as a whole, and/or - one or more compounds selected from the group consisting of CC-2-V1, CC-3-V1, CC- 3-V2, CC-4-V1, CC-3-V, CC-4-V and CC-5-V, preferably in a total concentration of 3 to 40%, more preferably from 5% to 30% based on the mixture as a whole, and/or - one or more compound(s) CCP-n-m and/or CCP-Vn-m and/or CPP-n-m, preferably selected from the group consisting of CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably in a total concentration of 4 to 35%, preferably 5 to 25% based on the mixture as a whole, and/or - one or more compound(s) CLP-n-m, CLP-n-Om and/or CLP-Vn-m, preferably selected from the group consisting of CLP-3-1, CLP-3-2, CLP-3-O1, CLP-3-O2 and CLP-V-1, preferably in a total concentration of 1 to 25%, preferably 2 to 15% based on the mixture as a whole, and/or - one or more compounds selected from the group consisting of PYP-n-m, PGIY-n-Om and PGP-n-2V, preferably in a total concentration of 2 to 20%, more preferably 2% to 15%, most preferably 2 to 10%, based on the mixture as a whole, and/or - one or more compound(s) PP-n-m and/or PP-n-nVm, preferably selected from the group consisting of PP-1-3, PP-1-4, PP-1-5, PP-1-2V and PP-1-2V1, preferably in a total concentration of 1 to 15%, preferably 2 to 10% based on the mixture as a whole, and/or - the compound PPGU-3-F, preferably in a concentration of 0.1% to 3% based on the mixture as a whole. It is advantageous for the liquid-crystalline medium according to the invention to preferably have a nematic phase from ≤ -20°C to ≥ 70°C, particularly preferably from ≤ -30°C to ≥ 80°C, very particularly preferably from ≤ -40°C to ≥ 90°C. The LC medium according to the invention preferably has a clearing temperature of 90°C or more, more preferably of 95°C or more. The expression "have a nematic phase" here means on the one hand that no smectic phase and no crystallisation are observed at low temperatures at the corresponding temperature and on the other hand that clearing still does not occur on heating from the nematic phase. The investigation at low temperatures is carried out in a flow viscometer at the corresponding temperature and checked by storage in test cells having a layer thickness corresponding to the electro-optical use for at least 100 hours. If the storage stability at a temperature of -20°C in a corresponding test cell is 1000 h or more, the LC medium is referred to as stable at this temperature. At temperatures of -30°C and -40°C, the corresponding times are 500 h and 250 h respectively. At high temperatures, the clearing point is measured by conventional methods in capillaries. The liquid-crystal mixture preferably has a nematic phase range of at least 60 K and a flow viscosity v20 of at most 30 mm2 · s-1 at 20°C. The mixture is nematic at a temperature of -20°C or less, preferably at -30°C or less, very preferably at -40°C or less. The values of the birefringence Δn in the liquid-crystal mixture are generally between 0.07 and 0.16, preferably between 0.08 and 0.15, very preferably between 0.09 and 0.14. In a preferred embodiment of the present invention, the LC medium has a birefringence in the range of from 0.090 to 0.110, preferably from 0.090 to 0.108. The liquid-crystal mixture according to the invention has a dielectric anisotropy Δ ε of -1.5 to -8.0, preferably of -3.0 to -6.0, in particular --3.8 to -4.5, The rotational viscosity γ1 at 20°C is preferably ≤ 250 mPa ·s, more preferably ≤ 200 mPa ·s, very preferably ≤ 180mPa ·s, in particular ≤ 160 mPa ·s. The liquid-crystal media according to the invention have relatively low values for the threshold voltage (V0). They are preferably in the range from 1.7 V to 3.0 V, particularly preferably ≤ 2.7 V and very particularly preferably ≤ 2.5 V. For the present invention, the term "threshold voltage" relates to the capacitive threshold (V0), also called the Freedericks threshold, unless explicitly indicated otherwise. In addition, the liquid-crystal media according to the invention have high values for the voltage holding ratio in liquid-crystal cells. In general, liquid-crystal media having a low addressing voltage or threshold voltage exhibit a lower voltage holding ratio than those having a higher addressing voltage or threshold voltage and vice versa. For the present invention, the term "dielectrically positive compounds" denotes compounds having a Δ ε > 1.5, the term "dielectrically neutral compounds" denotes those having -1.5 ≤ Δ ε ≤ 1.5 and the term "dielectrically negative compounds” denotes those having Δ ε < -1.5. The dielectric anisotropy of the compounds is determined here by dissolving 10 % of the compounds in a liquid-crystalline host and determining the capacitance of the resultant mixture in at least one test cell in each case having a layer thickness of 20 µm with homeotropic and with homogeneous surface alignment at 1 kHz. The measurement voltage is typically 0.5 V to 1.0 V, but is always lower than the capacitive threshold of the respective liquid-crystal mixture investigated. All temperature values indicated for the present invention are in °C. The LC media according to the invention are suitable for all VA-TFT (vertical alignment- thin film transistor) applications, such as, for example, VAN (vertically aligned nematic), MVA (multidomain VA), (S)-PVA (super patterned VA), ASV (advanced super view, or axially symmetric VA), and PSA (polymer sustained VA). They are furthermore suitable for IPS (in-plane switching) and FFS (fringe field switching) applications having negative Δ ε. Besides one or more compounds of the formula I, the LC medium preferably comprises 4 to 15, in particular 5 to 12, and particularly preferably < 10, compounds of the formulae IIA, IIB, IIC, IID, IIE and/or III and one or more compounds of the formula IV. Besides compounds of the formula I and the compounds of the formulae IIA, IIB, IIC and/or IID and/or III and IV, other constituents may also be present, for example in an amount of up to 45 % of the mixture as a whole, but preferably up to 35 %, in particular up to 10 %. The other constituents are preferably selected from nematic or nematogenic substances, in particular known substances, from the classes of the azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl cyclohexanecarboxylates, phenylcyclohexanes, cyclohexylbiphenyls, cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-biscyclohexylbiphenyls or cyclohexylpyrimidines, phenyl- or cyclohexyldioxanes, optionally halogenated stilbenes, benzyl phenyl ethers, tolanes and substituted cinnamic acid esters. The most important compounds which are suitable as constituents of liquid-crystal phases of this type can be characterised by the formula R in which L and E each denote a carbo- or heterocyclic ring system from the group formed by 1,4-disubstituted benzene and cyclohexane rings, 4,4’-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine and 1,3-dioxane rings, 2,6-disubstituted naphthalene, di- and tetrahydronaphthalene, quinazoline and tetrahydroquinazoline, G denotes -CH=CH- -N(O)=N- -CH=CQ- -CH=N(O)- -C ^C- -CH2-CH2- -CO-O- -CH2-O- -CO-S- -CH2-S- -CH=N- -COO-Phe-COO- -CF2O- -CF=CF- -OCF2- -OCH2- -(CH2)4- -(CH2)3O- or a C-C single bond, Q denotes halogen, preferably chlorine, or -CN, and RR1 and RR2 each denote alkyl, alkenyl, alkoxy, alkoxyalkyl or alkoxycarbonyloxy having up to 18, preferably up to 8, carbon atoms, or one of these radicals alternatively denotes CN, NC, NO2, NCS, CF3, SF5, OCF3, F, Cl or Br. In most of these compounds, RR1 and RR2 are different from one another, one of these radicals usually being an alkyl or alkoxy group. Other variants of the proposed substituents are also common. Many such substances or also mixtures thereof are commercially available. All these substances can be prepared by methods known from the literature. It goes without saying for the person skilled in the art that the VA, IPS or FFS mixture according to the invention may also comprise compounds in which, for example, H, N, O, Cl and F have been replaced by the corresponding isotopes. The LC medium has preferably a nematic LC phase. In a preferred embodiment the LC media contain one or more chiral dopants, preferably in a concentration from 0.01 to 1% by weight, very preferably from 0.05 to 0.5% by weight. The chiral dopants are preferably selected from the group consisting of compounds from Table C below, very preferably from the group consisting of R- or S- 1011, R- or S-2011, R- or S-3011, R- or S-4011, and R- or S-5011. In another preferred embodiment the LC media contain a racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph. In another preferred embodiment of the present invention the LC media contain one or more further stabilisers. Preferred stabilisers are selected from the compounds of formula H in which Ar denotes an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms, preferably 6 to 30 C atoms; Sp denotes a spacer group; RS denotes H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms; ZS denotes -O-, -C(O)O-, -(CH2)z- or –(CH2)zO-, or a single bond; HA denotes RH denotes H, O., CH3, OH or ORS, preferably H or O.; RS1, RS2, RS3 and RS4, identically or differently, denote alkyl having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3; G denotes H or RS or a group ZS-HA; z is an integer from 1 to 6; and q is 3 or 4. The compounds of formula H are described in EP3354710 A1 and EP3354709 A1. Preferred compounds of formula H are selected from the formulae H-1, H-2 and H-3: in which RH has the meanings given above and preferably denotes H or O., and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7, and Sp denotes a spacer group, preferably alkylene having 1 to 12 C atoms in which one or more non-adjacent - CH2- groups may be replaced with -O-. Preferred compounds of formula H-1 are those of formula H-1-1:
in which RH has the meanings given above and preferably denotes H or O., and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7. Very preferred compounds of formula H-1-1 are those of formula H-1-1-1: Preferred compounds of formula H-2 are those of formula H-2-1:
in which RH has the meanings given above and preferably denotes H or O., and n2, on each occurrence identically or differently, preferably identically, is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, and RS on each occurrence identically or differently, preferably identically, denotes alkyl having 1 to 6 C atoms, preferably n- butyl. Very preferred compounds of formula H-2-1 are those of formula H-2-1-1: Preferred compounds of formula H-3 are selected from the formula H-3-1:
in which Sp and RH have the meanings given above and RH preferably denotes H or O., and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7. Further preferred stabilisers are selected from the group consisting of the formulae ST- 1 to ST-18:
in which RST denotes H, an alkyl or alkoxy radical having 1 to 15 C atoms, wherein, in addition, one or more CH2 groups may each be replaced, independently of one another, by -C ≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, , on each occurrence, identically or differently, denotes , ZST each, independently of one another, denote -CO-O-, -O-CO-, -CF2O-, -OCF2-, - CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CH2O-, -C2F4-, -CH2CF2- , -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C ^C- or a single bond, L1 and L2 each, independently of one another, denote F, Cl, CH3, CF3 or CHF2, p denotes 0, 1 or 2, q denotes 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. Preferred compounds of formula ST are those selected from the formulae ST-3 and in particular: in which n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3 in which n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3 in which n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7
In the compounds of the formulae ST-3a and ST-3b, n preferably denotes 3. In the compounds of the formula ST-2a, n preferably denotes 7. Very preferred stabilisers are selected from the group of the compounds of the formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12: In another preferred embodiment the LC medium comprises one or more stabilisers selected from Table D below. Preferably the proportion of stabilisers in the LC medium is from 10 to 500 ppm, very preferably from 20 to 100 ppm. The LC medium according to the present invention may additionally comprise one or more further components or additives, preferably selected from the list including but not limited to co-monomers, chiral dopants, polymerization initiators, inhibitors, stabilisers, surfactants, wetting agents, lubricating agents, dispersing agents, hydrophobing agents, adhesive agents, flow improvers, defoaming agents, deaerators, diluents, reactive diluents, auxiliaries, colourants, dyes, pigments and nanoparticles. Furthermore, it is possible to add to the LC media, for example, 0 to 15% by weight of pleochroic dyes, furthermore nanoparticles, conductive salts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst.24, 249-258 (1973)), for improving the conductivity, or substances for modifying the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases. Substances of this type are described, for example, in DE-A 22 09 127, 2240864, 2321632, 2338281, 2450088, 2637430 and 2853728. The individual components of the above-listed preferred embodiments of the LC media according to the invention are either known or methods for the preparation thereof can readily be derived from the prior art by the person skilled in the relevant art, since they are based on standard methods described in the literature. Corresponding compounds of the formula CY are described, for example, in EP-A-0364538. Corresponding com- pounds of the formula IV are described, for example, in DE-A-2636684 and DE-A-33 21373. The LC media which can be used in accordance with the invention are prepared in a manner conventional per se, for example by mixing one or more of the above-mentioned compounds with one or more polymerizable compounds as defined above, and optionally with further liquid-crystalline compounds and/or additives. In general, the desired amount of the components used in lesser amount is dissolved in the components making up the principal constituent, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation, after thorough mixing. The invention furthermore relates to the process for the preparation of the LC media according to the invention. It goes without saying to the person skilled in the art that the LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes like deuterium etc. The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combina- tions are accessible. For the present invention and in the following examples, the structures of the liquid- crystal compounds are indicated by means of acronyms. Unless stated otherwise, the transformation into chemical formulae is done in accordance with Tables A.1 to A.3 below. All radicals C n H 2n+1 , C m H 2m+1 and ClH2l+1 or C n H 2n , C m H 2m and ClH2l are straight-chain alkyl radicals or alkylene radicals, in each case having n, m and l C atoms respectively. Preferably n, m and l are independently of each other 1, 2, 3, 4, 5, 6, or 7. Table A.1 shows the codes for the ring elements of the nuclei of the compound, Table A.2 lists the bridging units, and Table A.3 lists the meanings of the symbols for the left- and right-hand end groups of the molecules. The acronyms are composed of the codes for the ring elements with optional linking groups, followed by a first hyphen and the codes for the left-hand end group, and a second hyphen and the codes for the right-hand end group. Table A.1: Ring elements
Table A.2: Bridging units Table A.3: End groups
in which n and m are each integers, and the three dots "…" are placeholders for other abbreviations from this table. Table B shows illustrative structures of compounds together with their respective abbreviations which are preferred co-compounds according to the claimed mixture concept of the present invention. Table B In Table B, n, m, k and l are, independently of one another, each an integer, preferably 1 to 9 preferably 1 to 7, k and l may also be 0 and are preferably 0 to 4, more preferably 0 or 2 and most preferably 2, n is preferably 1, 2, 3, 4 or 5 or, in the combination “-nO-”, n is preferably 1, 2, 3 or 4, very preferably 2 or 4, m is preferably 1, 2, 3, 4 or 5 or, in the combination “-Om”, m is preferably 1, 2, 3 or 4, more preferably 2 or 4. The combination “-nVm” preferably is “2V1”. (O)CmH2m+1 means CmH2m+1 or OCmH2m+1.
In a preferred embodiment of the present invention, the LC media according to the invention comprise one or more compounds selected from the group consisting of compounds from Table B. Table C Table C shows possible chiral dopants which can be added to the LC media according to the invention with the concentration from 0 to 5 wt %, preferably 0.01 to 3 wt %.
The LC media preferably comprise 0 to 10% by weight, in particular 0.01 to 5% by weight, particularly preferably 0.1 to 3% by weight, of dopants. The LC media preferably comprise one or more dopants selected from the group consisting of compounds from Table C. Table D Table D shows possible stabilisers which can be added to the LC media according to the invention. Therein n denotes an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups are not shown.
The LC media preferably comprise 0 to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 1 ppm to 1% by weight, of stabilisers. The LC media preferably comprise one or more stabilisers selected from the group consisting of compounds from Table D. Examples The following examples explain the present invention without restricting it. However, they show the person skilled in the art preferred mixture concepts with compounds preferably to be employed and the respective concentrations thereof and combinations thereof with one another. In addition, the examples illustrate which properties and property combina- tions are accessible. In addition, the following abbreviations and symbols are used: V0 threshold voltage, capacitive [V] at 20°C, ne extraordinary refractive index at 20°C and 589 nm, no ordinary refractive index at 20°C and 589 nm, Δn optical anisotropy at 20°C and 589 nm, dielectric permittivity perpendicular to the director at 20°C and 1 kHz, dielectric permittivity parallel to the director at 20°C and 1 kHz, Δ ε dielectric anisotropy at 20°C and 1 kHz, cl.p., T(N,I) clearing point [°C], γ1 rotational viscosity at 20°C [mPa ^s], K1 elastic constant, "splay" deformation at 20°C [pN], K2 elastic constant, "twist" deformation at 20°C [pN], K3 elastic constant, "bend" deformation at 20°C [pN] Kavg average elastic constant at 20°C [pN] defined here as Kavg ≡ (3/2 K1 + K3) / 3 ^ (K1 + K2 + K3) / 3, LTS low-temperature stability of the phase, determined in test cells, VHR voltage holding ratio. Unless explicitly noted otherwise, all concentrations in the present application are quoted in per cent by weight and relate to the corresponding mixture as a whole, comprising all solid or liquid-crystalline components, without solvents. Unless explicitly noted otherwise, all temperature values indicated in the present application, such as, for example, for the melting point T(C,N), the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (°C). M.p. denotes melting point, cl.p. = clearing point. Furthermore, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperatures. All physical properties are and have been determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany, and apply for a temperature of 20°C, and Δn is determined at 589 nm and Δ ε at 1 kHz, unless explicitly indicated otherwise in each case. The term "threshold voltage" for the present invention relates to the capacitive threshold (V0), also known as the Freedericks threshold, unless explicitly indicated otherwise. In the examples, the optical threshold may also, as generally usual, be quoted for 10% relative contrast (V10). Unless stated otherwise, the process of polymerizing the polymerizable compounds in the PSA displays as described above and below is carried out at a temperature where the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably is carried out at room temperature. Unless stated otherwise, methods of preparing test cells and measuring their electrooptical and other properties are carried out by the methods as described hereinafter or in analogy thereto. The polymerizable compounds are polymerized in the display or test cell by irradiation with UV light of defined intensity for a prespecified time, with a voltage simultaneously being applied to the display (usually 10 V to 30 V alternating current, 1 kHz). The tilt angle is determined using the Mueller Matrix Polarimeter “AxoScan” from Axometrics. A low value (i.e. a large deviation from the 90° angle) corresponds to a large tilt here. Unless stated otherwise, the term "tilt angle" means the angle between the LC director and the substrate, and "LC director" means in a layer of LC molecules with uniform orientation the preferred orientation direction of the optical main axis of the LC molecules, which corresponds, in case of calamitic, uniaxially positive birefringent LC molecules, to their molecular long axis. In the following Examples, the following compounds A-1, A-2, B-1 to B-7, C, D, and/or E of formula I are added to the LC mixtures.
By using the compounds of formula I in the LC mixtures, it was surprisingly found that high average elastic constant Kavg can be achieved. While with fixed Kavg, lower ratio of rotational viscosity to the splay elastic constant γ1 / K11 can be achieved. In some of the following Examples, the compound F of formula III is added to the LC mixtures.
Example 1A The nematic LC mixture N1A is formulated as follows. To the mixture N1A are added 100 ppm of the stabiliser H-1-1-1. Example 1B The nematic LC mixture N1B is formulated as follows. To the mixture N1B are added 100 ppm of the stabiliser H-1-1-1. Example 1C The nematic LC mixture N1Cis formulated as follows. To the mixture N1C are added 100 ppm of the stabiliser H-1-1-1. Example 1D The nematic LC mixture N1D is formulated as follows. To the mixture N1D are added 100 ppm of the stabiliser H-1-1-1. Example 1E The nematic LC mixture N1E is formulated as follows. To the mixture N1E are added 100 ppm of the stabiliser H-1-1-1. Example 2 The nematic LC mixture N2 is formulated as follows. To the mixture N2 are added 150 ppm of the stabiliser ST-3a-1. Example 3 The nematic LC mixture N3 is formulated as follows.
To the mixture N3 are added 150 ppm of the stabiliser ST-3b-1. Example 4 The nematic LC mixture N4 is formulated as follows.
To the mixture N4 are added 50 ppm of the stabiliser H-2-1-1. Example 5 The nematic LC mixture N5 is formulated as follows.
To the mixture N5 are added 100 ppm of the stabiliser ST-8-1. Example 6 The nematic LC mixture N6 is formulated as follows. To the mixture N6 are added 50 ppm of the stabiliser ST-9-1. Example 7 The nematic LC mixture N7 is formulated as follows. To the mixture N7 are added 50 ppm of the stabiliser ST-12.
Example 8 The nematic LC mixture N8 is formulated as follows. To the mixture N8 are added 100 ppm of the stabiliser H-1-1-1. Example 9 The nematic LC mixture N9 is formulated as follows.
To the mixture N9 are added 150 ppm of the stabiliser ST-3a-1. Example 10 The nematic LC mixture N10 is formulated as follows.
To the mixture N10 are added 150 ppm of the stabiliser ST-3b-1. Example 11 The nematic LC mixture N11 is formulated as follows. To the mixture N11 are added 50 ppm of the stabiliser H-2-1-1. Example 12 The nematic LC mixture N12 is formulated as follows. To the mixture N12 are added 100 ppm of the stabiliser ST-11, in which q=8. Example 13 The nematic LC mixture N13 is formulated as follows.
wherein B(S)-4O-O1(c5), B(S)-5O-O1(c5), B(S)-6O-O1(c5) are To the mixture N13 are added 100 ppm of the stabiliser ST-11, in which q=8. Example 14 The nematic LC mixture N14 is formulated as follows.
To the mixture N14 are added 50 ppm of the stabiliser ST-9-1. Example 15 The nematic LC mixture N15 is formulated as follows. To the mixture N15 are added 50 ppm of the stabiliser ST-12. Example 16 The nematic LC mixture N16 is formulated as follows.
To the mixture N16 are added 100 ppm of the stabiliser H-1-1-1. Example 17 The nematic LC mixture N17 is formulated as follows. To the mixture N17 are added 150 ppm of the stabiliser ST-3a-1. Example 18 The nematic LC mixture N18 is formulated as follows.
To the mixture N18 are added 150 ppm of the stabiliser ST-3b-1. Example 19 The nematic LC mixture N19 is formulated as follows. To the mixture N19 are added 50 ppm of the stabiliser H-2-1-1. Example 20 The nematic LC mixture N20 is formulated as follows. To the mixture N20 are added 100 ppm of the stabiliser ST-8-1. Example 21 The nematic LC mixture N21 is formulated as follows.
To the mixture N21 are added 50 ppm of the stabiliser ST-9-1. Example 22 The nematic LC mixture N22 is formulated as follows. To the mixture N22 are added 50 ppm of the stabiliser ST-12. Example 23 The nematic LC mixture N23 is formulated as follows.
To the mixture N23 are added 100 ppm of the stabiliser H-1-1-1. Example 24 The nematic LC mixture N24 is formulated as follows. To the mixture N24 are added 150 ppm of the stabiliser ST-3a-1. To the mixture N25 are added 150 ppm of the stabiliser ST-3b-1. Example 26 The nematic LC mixture N26 is formulated as follows. To the mixture N26 are added 50 ppm of the stabiliser H-2-1-1. Example 27 The nematic LC mixture N27 is formulated as follows. To the mixture N27 are added 100 ppm of the stabiliser ST-8-1. Example 28 The nematic LC mixture N28 is formulated as follows. To the mixture N28 are added 50 ppm of the stabiliser ST-9-1. Example 29 The nematic LC mixture N29 is formulated as follows. To the mixture N29 are added 50 ppm of the stabiliser ST-12. Example 30 The nematic LC mixture N30 is formulated as follows.
To the mixture N30 are added 100 ppm of the stabiliser H-1-1-1. Example 31 The nematic LC mixture N31 is formulated as follows. To the mixture N31 are added 150 ppm of the stabiliser ST-3a-1. Example 32 The nematic LC mixture N32 is formulated as follows.
To the mixture N32 are added 150 ppm of the stabiliser ST-3b-1. Example 33 The nematic LC mixture N33 is formulated as follows. To the mixture N33 are added 50 ppm of the stabiliser H-2-1-1. Example 34 The nematic LC mixture N34 is formulated as follows.
wherein B(S)-4O-O1(c3) is To the mixture N34 are added 100 ppm of the stabiliser ST-8-1. Example 35 The nematic LC mixture N35 is formulated as follows. To the mixture N35 are added 50 ppm of the stabiliser ST-9-1. Example 36 The nematic LC mixture N36 is formulated as follows. To the mixture N36 are added 50 ppm of the stabiliser ST-12. Example 37 The nematic LC mixture N37 is formulated as follows.
To the mixture N37 are added 100 ppm of the stabiliser H-1-1-1. Example 38 The nematic LC mixture N38 is formulated as follows. To the mixture N38 are added 150 ppm of the stabiliser ST-3a-1. Example 39 The nematic LC mixture N39 is formulated as follows.
To the mixture N39 are added 150 ppm of the stabiliser ST-3b-1. Example 40 The nematic LC mixture N40 is formulated as follows. To the mixture N40 are added 50 ppm of the stabiliser H-2-1-1. Example 41 The nematic LC mixture N41 is formulated as follows.
To the mixture N41 are added 100 ppm of the stabiliser ST-8-1. Example 42 The nematic LC mixture N42 is formulated as follows. To the mixture N42 are added 50 ppm of the stabiliser ST-9-1. Example 43 The nematic LC mixture N43 is formulated as follows. To the mixture N43 are added 50 ppm of the stabiliser ST-12. Example 44 The nematic LC mixture N44 is formulated as follows. To the mixture N44 are added 100 ppm of the stabiliser H-1-1-1. Example 45 The nematic LC mixture N45 is formulated as follows. To the mixture N45 are added 150 ppm of the stabiliser ST-3a-1. Example 46 The nematic LC mixture N46 is formulated as follows.
To the mixture N46 are added 150 ppm of the stabiliser ST-3b-1. Example 47 The nematic LC mixture N47 is formulated as follows. To the mixture N47 are added 50 ppm of the stabiliser H-2-1-1. Example 48 The nematic LC mixture N48 is formulated as follows. wherein CLOY-(c5)1-O2 is To the mixture N48 are added 100 ppm of the stabiliser ST-8-1. Example 49 The nematic LC mixture N49 is formulated as follows.
To the mixture N49 are added 50 ppm of the stabiliser ST-9-1. Example 50 The nematic LC mixture N50 is formulated as follows. To the mixture N50 are added 50 ppm of the stabiliser ST-12. Example 51 The nematic LC mixture N51 is formulated as follows.
To the mixture N51 are added 100 ppm of the stabiliser H-1-1-1. Example 52 The nematic LC mixture N52 is formulated as follows. To the mixture N52 are added 150 ppm of the stabiliser ST-3a-1. Example 53 The nematic LC mixture N53 is formulated as follows. To the mixture N53 are added 150 ppm of the stabiliser ST-3b-1. Example 54 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-171 and 100 ppm of the stabiliser ST-3a-1 to the mixture of Example 1A. Example 55 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-171 and 100 ppm of the stabiliser ST-3a-1 to the mixture of Example 2. Example 56 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-1 and 100 ppm of the stabiliser ST-3b-1 to the mixture of Example 3. Example 57 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-35 and 50 ppm of the stabiliser H-1-1-1 to the mixture of Example 4. Example 58 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-120 and 150 ppm of the stabiliser ST-9-1 to the mixture of Example 5.
Example 59 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-142 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 6. Example 60 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-143 and 150 ppm of the stabiliser ST-3a-1 to the mixture of Example 7. Example 61 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-172 and 50 ppm of the stabiliser H-2-1-1 to the mixture of Example 8.
Example 62 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-159 and 50 ppm of the stabiliser H-2-1-1 to the mixture of Example 9. Example 63 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-145 to the mixture of Example 10. Example 64 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-156 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 11.
Example 65 A polymerizable mixture is prepared by adding 0.35% of the polymerizable compound RM-162 and 50 ppm of the stabiliser H-2-1-1 to the mixture of Example 12. Example 66 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-58 and 150 ppm of the stabiliser ST-3b-1 to the mixture of Example 13. Example 67 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-160 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 14.
Example 68 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-163 and 100 ppm of the stabiliser ST-9-1 to the mixture of Example 15. Example 69 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-64 and 150 ppm of the stabiliser ST-3b-1 to the mixture of Example 16. Example 70 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound a69 and 100 ppm of the stabiliser ST-8-1 to the mixture of Example 17. Example 71 A polymerizable mixture is prepared by adding 0.4% of the polymerizable compound RM-157 and 150 ppm of the stabiliser H-2-1-1 to the mixture of Example 18. Example 72 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-171, 0.1% of the polymerizable compound RM-1 and 150 ppm of the stabiliser ST- 3a-1 to the mixture of Example 19. Example 73 A polymerizable mixture is prepared by adding 0.2% of the polymerizable compound RM-35, 0.2% of the polymerizable compound RM-1 and 100 ppm of the stabiliser ST- 3b-1 to the mixture of Example 20. Example 74 A polymerizable mixture is prepared by adding 0.3% of the polymerizable compound RM-171, 0.1% of the polymerizable compound RM-64 and 100 ppm of the stabiliser H- 2-1-1 to the mixture of Example 21. Example 75 A polymerizable mixture is prepared by adding 0.1% of the polymerizable compound RM-120, 0.3% of the polymerizable compound RM-1 and 150 ppm of the stabiliser H-1- 1-1 to the mixture of Example 22. Example 76 A polymerizable mixture is prepared by adding 0.1% of the polymerizable compound RM-143, 0.3% of the polymerizable compound RM-1 and 150 ppm of the stabiliser ST- 3a-1 to the mixture of Example 23. Example 77 A polymerizable mixture is prepared by adding 0.2% of the polymerizable compound RM-171, 0.2% of the polymerizable compound RM-120 and 150 ppm of the stabiliser ST-8-1 to the mixture of Example 24. Example 78 The nematic LC mixture N78 is formulated as follows. To the mixture N78 are added 100 ppm of the stabiliser H-1-1-1. Example 79 The nematic LC mixture N79 is formulated as follows.
wherein PGS-2-1 is To the mixture N79 are added 150 ppm of the stabiliser ST-3a-1. Example 80 The nematic LC mixture N80 is formulated as follows. To the mixture N80 are added 150 ppm of the stabiliser ST-3b-1. Example 81 The nematic LC mixture N81 is formulated as follows.
To the mixture N81 are added 50 ppm of the stabiliser H-2-1-1. Example 82 The nematic LC mixture N82 is formulated as follows. To the mixture N82 are added 100 ppm of the stabiliser ST-8-1. Example 83 The nematic LC mixture N83 is formulated as follows. To the mixture N83 are added 50 ppm of the stabiliser ST-9-1. Example 84 The nematic LC mixture N84 is formulated as follows. To the mixture N84 are added 50 ppm of the stabiliser ST-12. Example 85 The nematic LC mixture N85 is formulated as follows. To the mixture N85 are added 100 ppm of the stabiliser H-1-1-1. Example 86 The nematic LC mixture N86 is formulated as follows. To the mixture N86 are added 150 ppm of the stabiliser ST-3a-1. Example 87 The nematic LC mixture N87 is formulated as follows. To the mixture N87 are added 150 ppm of the stabiliser ST-3b-1. Example 88 The nematic LC mixture N88 is formulated as follows. To the mixture N88 are added 50 ppm of the stabiliser H-2-1-1. Example 89 The nematic LC mixture N89 is formulated as follows. To the mixture N89 are added 100 ppm of the stabiliser ST-8-1. Example 90 The nematic LC mixture N90 is formulated as follows. To the mixture N90 are added 50 ppm of the stabiliser ST-9-1. Example 91 The nematic LC mixture N91 is formulated as follows. To the mixture N91 are added 50 ppm of the stabiliser ST-12. Example 92 The nematic LC mixture N92 is formulated as follows. To the mixture N92 are added 100 ppm of the stabiliser H-1-1-1. Example 93 The nematic LC mixture N93 is formulated as follows.
To the mixture N93 are added 150 ppm of the stabiliser ST-3a-1. Example 94 The nematic LC mixture N94 is formulated as follows. To the mixture N94 are added 150 ppm of the stabiliser ST-3b-1. Example 95 The nematic LC mixture N95 is formulated as follows.
To the mixture N95 are added 50 ppm of the stabiliser H-2-1-1. Example 96 The nematic LC mixture N96 is formulated as follows. To the mixture N96 are added 100 ppm of the stabiliser ST-8-1. Example 97 The nematic LC mixture N97 is formulated as follows.
To the mixture N97 are added 50 ppm of the stabiliser ST-9-1. Example 98 The nematic LC mixture N98 is formulated as follows. To the mixture N98 are added 50 ppm of the stabiliser ST-12. Example 99 The nematic LC mixture N99 is formulated as follows.
To the mixture N99 are added 100 ppm of the stabiliser H-1-1-1. Example 100 The nematic LC mixture N100 is formulated as follows. To the mixture N100 are added 150 ppm of the stabiliser ST-3a-1. Example 101 The nematic LC mixture N101 is formulated as follows. To the mixture N101 are added 150 ppm of the stabiliser ST-3b-1. Example 102 The nematic LC mixture N102 is formulated as follows. To the mixture N102 are added 50 ppm of the stabiliser H-2-1-1. Example 103 The nematic LC mixture N103 is formulated as follows. To the mixture N103 are added 100 ppm of the stabiliser ST-8-1. Example 104 The nematic LC mixture N104 is formulated as follows.
To the mixture N104 are added 50 ppm of the stabiliser ST-9-1. Example 105 The nematic LC mixture N105 is formulated as follows. wherein CCP-1V2-1 is To the mixture N105 are added 50 ppm of the stabiliser ST-12. Example 106 The nematic LC mixture N106 is formulated as follows.
wherein PYP-2-(c5) is To the mixture N106 are added 100 ppm of the stabiliser H-1-1-1. Example 107 The nematic LC mixture N107 is formulated as follows. wherein PYP-2-1(c3) is To the mixture N107 are added 150 ppm of the stabiliser ST-3a-1. Example 108 The nematic LC mixture N108 is formulated as follows. To the mixture N108 are added 150 ppm of the stabiliser ST-3b-1. Example 109 The nematic LC mixture N109 is formulated as follows. To the mixture N109 are added 50 ppm of the stabiliser H-2-1-1. Example 110 The nematic LC mixture N110 is formulated as follows.
To the mixture N110 are added 100 ppm of the stabiliser ST-8-1. Example 111 The nematic LC mixture N111 is formulated as follows. To the mixture N111 are added 50 ppm of the stabiliser ST-9-1. Example 112 The nematic LC mixture N112 is formulated as follows. To the mixture N112 are added 50 ppm of the stabiliser ST-12. Example 113 The nematic LC mixture N113 is formulated as follows. To the mixture N113 are added 100 ppm of the stabiliser H-1-1-1. Example 114 The nematic LC mixture N114 is formulated as follows. To the mixture N114 are added 150 ppm of the stabiliser ST-3a-1. Example 115 The nematic LC mixture N115 is formulated as follows. To the mixture N115 are added 150 ppm of the stabiliser ST-3b-1.

Claims

Claims 1. A liquid crystal medium comprising one or more compounds of formula I in which R11 and R12 straight chain, branched or cyclic alkyl or alkoxy radical having 1 to 12 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-,- CH=CH-, -C ≡C-, in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F or Cl; A1 and A2 a group selected from the following formulae
Z1 and Z2 independently of one another, identically or differently, denotes a single bond, -CH2O-, -(CO)O-, -CF2O-, , -CF2CF2-, -CH2CF2-, -CH2CH2-, -CH=CH-, -CH=CF-, -CF=CF- or -C ≡C-, where asymmetrical bridges may be oriented to both sides, L1, L2, L3 and L4 F, Cl, OCF3,CF3, CH3, CH2F or CHF2, Y H, F, Cl, CF3, CHF2 or CH3, LC CH3 or O CH3, a1 denotes 0; 1, 2 or 3, a2 denotes 0, 1, or 2.
2. The liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds selected from the group of compounds of the formulae IA, IB, IC,ID, and IE,
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning: R11, R12 H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted or monosubstituted by F, Cl, CN or CF3 and where, in addition, one or more CH2 groups in these radicals may be replaced by -O-, -S-,-C ^C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O- and/or S-atoms are not linked directly to one another, L1 to L4 F, Cl, CF3 or CHF2, Y H, F, Cl, CF3, CHF2 or CH3, Z1, Z2 a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, p 0, 1 or 2, and q 0 or 1.
3. The liquid crystal medium according to claim 1 or 2, wherein the medium comprises one or more compounds selected from the group of the formula II, wherein the individual radicals, independently of each other and on each occurrence identically or differently, have the following meanings: R21 and R22 H, straight chain, branched or cyclic alkyl or alkoxy having 1 to 20 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CH=CH-, -C ^C-, in such a manner that O- and/or S-atoms are not directly connected with each other, and wherein one or more H atoms are each optionally replaced by F, Cl, CN or CF3, A1 and A2 a group selected from the following formulae
Z1 and Z2 -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, - O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, L1, L2, L3 and L4 F, Cl, OCF3, CF3, CH3, CH2F or CHF2, Y H, F, Cl, CF3, CHF2 or CH3, LC CH3 or OCH3, a1 0, 1 or 2, a2 0 or 1.
4. The liquid crystal medium according to one or more of claims 1 to 3, wherein the medium comprises one or more compounds selected from the group of the formulae IIA, IIB, IIC, IID, and IIE,
in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meanings: R21, R22 H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted or monosubstituted by F, Cl, CN or CF3 and where, in addition, one or more CH2 groups in these radicals may be replaced by -O-, -S-,-C ^C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O- and/or S-atoms are not linked directly to one another, L1 to L4 F, Cl, CF3 or CHF2, Y H, F, Cl, CF3, CHF2 or CH3, Z1, Z2 a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, - OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CH=CHCH2O, p 0, 1 or 2, and q 0 or 1.
5. The liquid crystal medium according to one or more of claims 1 to 4, wherein the medium comprises one or more compounds of formula IIA-Y in which R21 and R22 have one of the meanings given in formula IIA above, and L1 and L2, identically or differently, denote F or Cl. 6. The liquid crystal medium according to one or more of claims 1 to 5, wherein the medium comprises one or more compounds of formula III and/or one or more compounds of formula IIIA in which R31 and R32, each, independently of one another, denote H, an alkyl or alkoxy radical having 1 to 15 C atoms, preferably having 1 to 7 C atoms, where one or more -CH2- groups in these radicals may each be replaced, independently of one another, by , -C ^C-, -CF2O-, -OCF2-, -CH=CH-, by -O-, -CO-O- or -O-CO- in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, A3 on each occurrence, independently of one another, denotes a) 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-, b) a 1,4-phenylene radical, in which one or two CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4- tetrahydronaphthalene-2,
6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the radicals a), b) and c) may be mono- or polysubstituted by halogen atoms, n denotes 0, 1 or 2, Z3 on each occurrence independently of one another denotes -CO-O-, -O-CO-, -CF2O- , -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, - (CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2 -, -CF=CF-, - CH=CF-, -CF=CH-, -CH=CH-, -C ^C- or a single bond, L31 and L32, each, independently of one another, denote F, Cl, CF3 or CHF2, and Y1 and Y2, each, independently of one another, denote H, F, Cl, CF3, CHF2, CH3 or OCH3.
7. The liquid crystal medium according to one or more of claims 1 to 6, wherein the medium comprises one or more compounds selected from the compounds of the formulae III-1 and/or III-6
in which the occurring groups have the same meanings as given under formula III.
8. The liquid crystal medium according to any one of claims 1 to 7, wherein the medium comprises one or more compounds of formula IV in which R41 denotes an unsubstituted alkyl radical having 1 to 7 C atoms where, in addition, one or more CH2 groups may be replaced by or an unsubstituted alkenyl radical having 2 to 7 C atoms, and R42 denotes an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkoxy radical having 1 to 6 C atoms, or an unsub- stituted alkenyl radical having 2 to 7 C atoms.
9. The liquid crystal medium according to any one of claims 1 to 8, wherein the medium comprises one or more compounds of the formula V in which R51 and R52 independently of one another, denote H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by F, Cl, CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may be replaced by -O-, -S-,-C ^C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- in such a way that O atoms are not linked directly to one another, identically or differently, denote Z51 , Z52 each, independently of one another, denote -CH2-CH2-, -CH2- O-,-CH=CH-, -C≡C-, -COO- or a single bond, and n is 1 or 2.
10. The liquid crystal medium according to any one of claims 1 to 9, wherein the medium comprises one or more compounds of the formulae BC and/or PH-1
in which R81 and R82 each, independently of one another, denote H, an alkyl, alkoxy or alkenyl radical having up to 15 C atoms which is unsubstituted or monosubstituted by F, Cl, CN or CF3 and where, in addition, one or more CH2 groups in these radicals may be replaced by -O-, - S-, -C ≡C-, -CF2O-, -OCF2-, -OC-O-, -O-CO- , in such a way that O- and/or S-atoms are not linked directly to one another, c denotes 0, 1 or 2, and Y1, Y2, Y3, Y4, each, independently of one another, denote H, F, Cl, CF3, CHF2, CH3 or OCH3, and/or wherein the medium comprises one or more compounds of the formulae IVa-1 to IVa- 4 and/or IVb-1 to IVb-3
in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2 to 6 C atoms, and/or wherein the medium comprises one or more compounds of the formulae VI-1 to VI-25, and/or wherein the medium comprises one or more compounds of the formula PGS-n-m in which n and m, independently of one another, each denote an integer from 1 to 9.
11. The liquid crystal medium according to one or more of claims 1 to 10, wherein the medium additionally comprises one or more additives selected from the group consisting of stabilisers, chiral dopants, and polymerization initiators.
12. A process for preparing an LC medium according to one or more of claims 1 to 11, comprising the steps of mixing one or more compounds of formula I with one or more compounds of formula II and/or formula III and optionally with further LC compounds and/or additives.
13. A liquid crystal display comprising the liquid crystal medium according to one or more of claims 1 to 11.
14. The display according to claim 13, wherein the display is a VA, IPS, FFS, UB-FFS or UBplus display.
15. Use of the liquid crystal medium according to one or more of claims 1 to 11 for energy-saving LC displays.
EP24712182.5A 2023-03-16 2024-03-13 Liquid-crystal medium Pending EP4680691A1 (en)

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