WO2019179962A1 - Milieu cristallin liquide - Google Patents

Milieu cristallin liquide Download PDF

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WO2019179962A1
WO2019179962A1 PCT/EP2019/056741 EP2019056741W WO2019179962A1 WO 2019179962 A1 WO2019179962 A1 WO 2019179962A1 EP 2019056741 W EP2019056741 W EP 2019056741W WO 2019179962 A1 WO2019179962 A1 WO 2019179962A1
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cyc
phe
phel
independently
groups
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PCT/EP2019/056741
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Martin Engel
Simon SIEMIANOWSKI
Sven Christian Laut
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Merck Patent Gmbh
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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
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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
    • C09K19/3098—Unsaturated non-aromatic rings, e.g. cyclohexene rings
    • C—CHEMISTRY; METALLURGY
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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
    • C—CHEMISTRY; METALLURGY
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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
    • C09K19/34—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
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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
    • 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
    • C—CHEMISTRY; METALLURGY
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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
    • C09K19/10—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
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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
    • C09K19/10—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
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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
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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)
    • C09K2019/3009—Cy-Ph
    • C—CHEMISTRY; METALLURGY
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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)
    • C09K2019/301—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
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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)
    • C09K2019/3016—Cy-Ph-Ph
    • C—CHEMISTRY; METALLURGY
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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)
    • C09K2019/3027—Compounds comprising 1,4-cyclohexylene and 2,3-difluoro-1,4-phenylene

Definitions

  • the present invention relates to liquid-crystal media, to the use of these liquid-crystal media in liquid-crystal displays, and to these liquid-crystal dis- plays, particularly liquid-crystal displays which use the fringe field switching (FFS) effect with dielectrically negative liquid crystals.
  • FFS fringe field switching
  • liquid-crystal displays for example of the TN (twisted nematic) type the electric fields for re-alignment are generated essentially perpendicular to the liquid-crystal layer.
  • IPS displays 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 interdig itated, 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.
  • EP 0 588 568 discloses various possibilities for the design of the electrodes and for addressing an IPS display.
  • DE 198 24 137 likewise describes various embodiments of such IPS displays.
  • Liquid-crystalline materials for IPS displays of this type are described, for example, in DE 195 28 104.
  • 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. Furthermore, FFS displays have 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 said 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.
  • 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.
  • IPS in-plane switching
  • FFS fringe field switching
  • Both the IPS and the FFS technology have certain advantages over other LCD technologies, such as, for example, the vertical alignment (VA) technology, e.g. a broad viewing angle dependency of the contrast.
  • VA vertical alignment
  • a further improvement has been achieved by the so-called UB-FFS mode, discussed e.g. in Engel, Martin et al., (2015) 43.1 : Invited Paper.
  • UB-FFS New Materials for Advanced Mobile Applications, SID Symposium Digest of Technical Papers, 46, doi: 10.1002/sdtp.10235.
  • One of the unique features of UB-FFS in contrast to the traditional FFS technology is that it enables higher transmittance, which allows operation of the panel with less energy consumption.
  • UB-FFS is known for having a lower flicker compared to FFS.
  • Low flicker enables further energy saving by decreasing the panel driving frequency.
  • any further improvement of reducing flicker is a key requirement for UB-FFS mixtures.
  • As a root cause the flexo electric effect is considered to generate flicker. So far it is extremely difficult to identify LC materials that reduce flicker.
  • the flicker phenomenon is well-known for occurring at low frequencies for every panel technology if the voltage decreases over time, leading to a decrease of transmittance and a sudden increase in transmittance by refreshing the voltage.
  • UB-FFS flicker is understood as the variation of transmittance depending on the polarity of the applied voltage.
  • the invention relates to a liquid-crystal medium comprising one or more compounds selected from the group of compounds of the formulae Y-1 to in which
  • R Y1 and R Y2 each, independently of one another, denote FI, an alkyl or alkenyl radical having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CFI2 groups in these radicals may be replaced by -0-, -S-,
  • R 1 1 denotes a straight-chain or branched alkyl group, in which one or more non-adjacent and non-terminal CH 2 groups may be replaced, in each occurrence independently from one another, by -0-,
  • R 12 denotes F, Cl, CN, NCS, or a straight-chain or branched alkyl group, which may be unsubstituted, mono- or polysubstituted by halogen or CN and in which one or more non-adjacent and non-terminal CFI 2 groups may be replaced, in each occurrence independently from one another, by -0-, -S-, -NH-, -N(CH 3 )-, -CO-, -COO-,
  • a 11 denotes 1 ,4-cyclohexylene
  • a 12 to A 14 each independently in each occurrence denote, 1 ,4- phenylene, wherein in addition one or more CFI groups may be replaced by N, trans-1 , 4-cyclo-hexylene in which, in addition, one or two non-adjacent CFI2 groups may be replaced by O and/or S, 1 ,4-cyclohexylene, naphthalene-2, 6-diyl, decahydro-naphthalene-2,6-diyl,
  • Z 11 and Z 12 are, independently of each other in each occurrence, a single bond, -COO-, -OCO-, -O-CO-O-, -OCFI2-,
  • X 1 1 and X 12 are independently from one another selected from a single bond, -C0-0-, -0-C0-, -O-COO-, -0-,
  • -CH CH-, -CoC-, -CF2-O-, -O-CF2-, -CF2-CF2-,
  • R 21 and R 22 denote independently FI, F, Cl, CN, NCS or a straight- chain or branched alkyl group, which may be
  • a 21 to A 24 denote independently in each occurrence a aryl-
  • heteroaryl-, and heterocyclic group preferably 1 ,4- phenylene, wherein in addition one or more CFI groups may be replaced by N, 1 ,4-bicyclo-(2,2,2)-octylene, naphthalene-2, 6-diyl, decahydro-naphthalene-2,6-diyl,
  • alkoxycarbonyl groups wherein one or more FI atoms may be substituted by F or Cl,
  • R 31 and R 32 have each and independently from another one of the meanings as given for R 21 and R 22 under formula II, A 31 to A 36 have each and independently from another one of the meanings as given for A 21 to A 24 under formula II, Z 31 and Z 32 are each independently in each occurrence,
  • -CH CH-COO-
  • b denotes an integer from 1 to 15, preferably an odd (i.e.
  • R 41 and R 42 have each and independently one of the meanings as given above for R 21 under formula II,
  • a 41 to A 44 have each and independently one of the meanings as given above for A 21 under formula II,
  • Z 41 and Z 42 are each independently in each occurrence
  • -CH CH-COO-
  • d denotes an integer from 1 to 15, preferably an odd (i.e.
  • R 51 and R 52 have each and independently one of the meanings as given above for R 21 under formula II,
  • a 51 to A 53 have each and independently one of the meanings as given above for A 21 under formula II,
  • Z 51 and Z 52 are each independently in each occurrence
  • -CH CH-COO-
  • R 61 and R 62 have each and independently one of the meanings as given above for R 21 under formula II,
  • a 61 to A 64 have each and independently one of the meanings as given above for A 21 under formula II,
  • Z 61 denotes -0-, -COO-, -OCO-, -0-C0-0-, -OCH 2 -, -CH 2 0,
  • COO- or -0C0- h denotes 0 or 1 and g denotes an integer from 1 to 15, preferably an odd (i.e. uneven) integer and, more preferably 3, 5, 7 or 9;
  • R 71 and R 72 have each and independently one of the meanings as given above for R 21 under formula II,
  • a 71 to A 76 have each and independently one of the meanings as given above for A 21 under formula II,
  • Z 71 to Z 74 each and independently denotes -COO-, -OCO-,
  • j denotes an integer from 1 to 15, preferably an odd (i.e.
  • the present invention also relates to electro-optical displays or electro- optical components which contain liquid-crystalline media according to the invention. Preference is given to electro-optical displays which are based on the FFS effect and in particular those which are addressed by means of an active-matrix addressing device.
  • the present invention further relates to the use of a liquid-crystalline medium according to the invention in an electro-optical display or in an electro-optical component, and to a process for the preparation of the liquid-crystalline media according to the invention, characterised in that one or more compounds of the formula Y-1 and/or Y-2 and/or Y-3 and/or Y-4 are mixed with one or more compounds selected from the group of compounds of the formulae I, II, III, IV, V, VI and VII, and preferably with one or more further compounds, preferably selected from the group of the compounds of the formulae C and/or P defined below.
  • the media according to the invention enable displays, in particular FFS displays, which exhibit advantageously low flicker.
  • liquid crystal means a compound that under suitable conditions of temperature, pressure and concentration can exist as a mesophase (nematic, smectic, etc.) or in particular as a LC phase.
  • mesophase nematic, smectic, etc.
  • Non-amphiphilic mesogenic compounds comprise for example one or more calamitic, banana-shaped or discotic mesogenic groups.
  • mesogenic group means in this context, a group with the ability to induce liquid crystal (LC) phase behaviour.
  • the compounds comprising mesogenic groups do not necessarily have to exhibit an LC phase themselves. It is also possible that they show LC phase behaviour only in mixtures with other compounds.
  • liquid crystal is used hereinafter for both mesogenic and LC materials.
  • aryl and heteroaryl groups encompass groups, which can be monocyclic or polycyclic, i.e. they can have one ring (such as, for example, phenyl) or two or more rings, which may also be fused (such as, for example, naphthyl) or covalently linked (such as, for example, biphenyl) or contain a combination of fused and linked rings.
  • Heteroaryl groups contain one or more heteroatoms, preferably selected from O, N, S and Se. Particular preference is given to mono-, bi- or tricyclic aryl groups having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl groups having 2 to 25 C atoms, which optionally contain fused rings and which are optionally substituted. Preference is furthermore given to 5 , 6 or 7-membered aryl and heteroaryl groups, in which, in addition, one or more CH groups may be replaced by N, S or O in such a way that O atoms and/or S atoms are not linked directly to one another.
  • Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1 ,1 ':3',1"]terphenyl-2'-yl, naphthyl, anthracene, binaphthyl, phenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, more preferably 1 ,4- phenylene, 4,4’- biphenylene, 1 , 4-tephenylene.
  • Preferred heteroaryl groups are, for example, 5 membered rings, such as pyrrole, pyrazole, imidazole, 1 ,2,3-triazole, 1 ,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1 ,2 thiazole, 1 ,3-thiazole, 1 ,2,3-oxadiazole, 1 ,2,4 oxadiazole, 1 ,2,5-oxadiazole, 1 ,3,4-oxadiazole, 1 ,2,3-thiadiazole, 1 ,2,4-thiadiazole, 1 ,2,5-thiadiazole, 1 ,3,4-thiadiazole, 6 membered rings, such as pyridine, pyridazine, pyrimidine, pyrazine, 1 ,3,5- triazine, 1 ,2,4-triazine, 1
  • indole iso-indole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphth- imidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole, phen- anthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5, 6-quinoline, benzo-6,7-quino 1ine, benzo-7, 8-quinoline, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline,
  • the term“(non-aromatic) alicyclic and heterocyclic groups” encompass both saturated rings, i.e. those that contain exclusively single bonds and partially unsaturated rings, i.e. those that may also contain multiple bonds.
  • Heterocyclic rings contain one or more heteroatoms, preferably selected from Si, O, N, S and Se.
  • the (non- aromatic) alicyclic and heterocyclic groups can be monocyclic, i.e. contain only one ring (such as, for example, cyclohexane) or polycyclic, i.e. contain a plurality of rings (such as, for example, decahydro-naphthalene or bicyclooctane). Particular preference is given to saturated groups.
  • Preference is furthermore given to mono-, bi- or tricyclic groups having 3 to 25 C atoms, which optionally contain fused rings and that are optionally substituted. Preference is furthermore given to 5-, 6-, 7- or 8-membered carbocyclic groups in which, in addition, one or more C atoms may be replaced by Si and/or one or more CH groups may be replaced by N and/or one or more non-adjacent CFh groups may be replaced by -O- and/or -S-.
  • Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups, such as cyclopentane, tetrahydrofuran, tetrahydrothiophene, pyrrolidine, 6-membered groups, such as cyclohexane, silinane,
  • cyclohexene tetrahydropyran, tetrahydrothiopyran, 1 ,3-dioxane, 1 ,3- dithiane, piperidine, 7-membered groups, such as cycloheptane and fused groups, such as tetrahydronaphthalene, decahydronaphthalene, indane, bicyclo[1.1.IJ-'pentane-l ,3-diyl, bicyclo[2.2.2]octane-1 ,4-diyl,
  • aryl-, heteroaryl-, alicyclic- and heterocyclic groups are 1 ,4-phenylene, 4,4’-biphenylene, 1 , 4-terphenylene, 1 ,4-cyclohexylene, 4,4’- bicyclohexylene and 3,17- hexadecahydro-cyclopenta[a]-phenanthrene, optionally being substituted by one or more identical or different groups L.
  • Preferred substituents of the above-mentioned aryl-, heteroaryl-, alicyclic- and heterocyclic groups (L) are, for example, solubility-promoting groups, such as alkyl or alkoxy and electron-withdrawing groups, such as fluorine, nitro or nitrile.
  • substituents are, for example, halogen, CN, NO2,
  • halogen denotes F, Cl, Br or I.
  • alkyl also encompass polyvalent groups, for example alkylene, arylene,
  • aryl denotes an aromatic carbon group or a group derived there from.
  • heteroaryl denotes “aryl” in accordance with the above definition containing one or more heteroatoms.
  • Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclo- pentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecanyl, trifluoro- methyl, peril uoro-n-butyl, 2,2,2-trifluoroethyl, peril uorooctyl, perfluoro- hexyl, etc.
  • Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxy- ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, 2- methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, n- decoxy, n-undecoxy, n-dodecoxy.
  • Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl.
  • Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl.
  • Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino.
  • chiral in general is used to describe an object that is non- superimposable on its mirror image.
  • “Achiral” (non- chiral) objects are objects that are identical to their mirror image.
  • bimesogenic compound or“bimesogen” relates to compounds comprising two mesogenic groups in the molecule. Just like normal mesogens, they can form many mesophases, depending on their structure. In particular, bimesogenic compound may induce a second nematic phase, when added to a nematic liquid crystal medium. Bimesogenic compounds are also known as“dimeric liquid crystals”.
  • Bimesogens are disclosed in for example WO 2015/002114 A1 ,
  • the director In case of uniaxial ordering of such anisotropic molecules, the director is the axis of anisotropy.
  • the term“alignment” or“orientation” relates to alignment (orientation ordering) of anisotropic units of material such as small molecules or fragments of big molecules in a common direction named“alignment direction”.
  • the liquid- crystalline director coincides with the alignment direction so that the alignment direction corresponds to the direction of the anisotropy axis of the material.
  • planar orientation/alignment for example in a layer of an liquid- crystalline material, means that the long molecular axes (in case of calamitic compounds) or the short molecular axes (in case of discotic compounds) of a proportion of the liquid-crystalline molecules are oriented substantially parallel (about 180°) to the plane of the layer.
  • the term "homeotropic orientation/alignment”, for example in a layer of a liquid-crystalline material, means that the long molecular axes (in case of calamitic compounds) or the short molecular axes (in case of discotic compounds) of a proportion of the liquid-crystalline molecules are oriented at an angle Q ("tilt angle") between about 80° to 90° relative to the plane of the layer.
  • the terms "uniform orientation” or "uniform alignment" of an liquid- crystalline material, for example in a layer of the material mean that the long molecular axes (in case of calamitic compounds) or the short molecular axes (in case of discotic compounds) of the liquid-crystalline molecules are oriented substantially in the same direction. In other words, the lines of liquid-crystalline director are parallel.
  • the wavelength of light generally referred to in this application is 550 nm, unless explicitly specified otherwise.
  • the birefringence Dh herein is defined by the following equation
  • the extraordinary refractive index n e and the ordinary refractive index n 0 can be measured using an Abbe refractometer.
  • the term“dielectrically positive” is used for compounds or components with De > 3.0,“dielectrically neutral” with -1 .5 ⁇ De ⁇ 3.0 and“dielectrically negative” with De ⁇ -1 .5.
  • De is determined at a frequency of 1 kHz and at 20°C.
  • the dielectric anisotropy of the respective compound is determined from the results of a solution of 10 % of the respective individual compound in a nematic host mixture. In case the solubility of the respective compound in the host medium is less than 10 % its concentration is reduced by a factor of 2 until the resultant medium is stable enough at least to allow the determination of its properties.
  • the concentration is kept at least at 5 %, however, in order to keep the significance of the results a high as possible.
  • the capacitance of the test mixtures are determined both in a cell with homeotropic and with homogeneous alignment.
  • the cell gap of both types of cells is
  • the voltage applied is a rectangular wave with a frequency of 1 kHz and a root mean square value typically of 0.5 V to 1 .0 V; however, it is always selected to be below the capacitive threshold of the respective test mixture.
  • De is defined as (e
  • the dielectric permittivity of the compounds is determined from the change of the respective values of a host medium upon addition of the compounds of interest. The values are extrapolated to a concentration of the compounds of interest of 100 %.
  • a typical host medium is ZLI-4792 or BL-087 both commercially available from Merck, Darmstadt.
  • trans-1 ,4-cyclohexylene denote 1 ,4-phenylene.
  • Phe in these groups is 1 ,4-phenylene
  • PheL is a 1 ,4-phenylene group which is substituted by 1 to 4 groups L, with L being preferably F, Cl, CN, OFI, NO2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, OFI, NO2, CFI3, C2FI5, OCFI3, OC2FI5, COCHs, COC2H5, COOCHs, COOC2H5, CFs, OCFs, OCHF2, OC2F5, in particular F, Cl, CN, CFI3, C2FI5, OCFI3, COCFI3 and OCF3, most preferably F, Cl, CFI3, OCFI3 and COCFIs and Cyc is 1 ,4-
  • Cyc is 1 ,4-cyclohexlene, preferably trans-1 ,4-cyclohexlene,
  • Phe is 1 ,4-phenylene
  • PheL is 1 ,4-phenylene, which is substituted by one, two or three fluorine atoms, by one or two Cl atoms or by one Cl atom and one F atom and
  • Z in each case independently has one of the meanings of Z 11 as given under formula I and if present twice, preferably one of Z is -COO-, -OCO-, -CH2-O-, -O-CH2-, - CF2-O- or -O-CF2-.
  • MG-1 1 is selected from the sub-formulae not containing two groups Z, more preferably from MG-1 1 -2 to MG-1 1 -13, even more preferably from MG-1 1 -2 or MG-1 1 -3.
  • Phe in these groups is 1 ,4-phenylene
  • PheL is a 1 ,4-phenylene group which is substituted by 1 to 4 groups L, with L being preferably F, Cl, CN, OFI, NO 2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, OH, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCHs, COOC2H5, CFs, OCFs, OCHF2, OC2F5, in particular F, Cl, CN, CH3, C 2 H 5 , OCH3, COCH3 and OCF3, most preferably F, Cl, CH3, OCH3 and COCHs and Cyc is 1 ,4-cyclohexy
  • Cyc is 1 ,4-cyclohexlene, preferably trans-1 ,4-cyclohexlene,
  • Phe is 1 ,4-phenylene
  • PheL is 1 ,4-phenylene, which is substituted by one, two or three fluorine atoms, by one or two Cl atoms or by one Cl atom and one F atom and
  • Z in each case independently has one of the meanings of Z 11 as given under formula I and if present twice, preferably one of Z is -COO-, -OCO-, -CH2-O-, -O-CH2-, - CF2-O- or -O-CF2-.
  • PheL preferably denotes the group furthermore
  • L is preferably F, Cl, CFb, OCH3 and COCH3 .
  • MG-12 is selected from the sub-formulae not containing two groups Z, more preferably from MG-12-1 to MG-12-38, even more preferably from MG-12-4 or MG-12-38, in particular, from MG-12-9 to MG- 12-12 or MG-12-32 to MG-12-38.
  • the compounds of formula I are unsymmetric compounds, which comprise different mesogenic groups MG-11 and MG-12 .
  • MG-11 and MG-12 each comprise two or three six-atomic rings, more preferably MG-11 and MG-12 each comprise two six-atomic rings or MG-11 comprises two six-atomic rings and MG-12 comprises three six-atomic rings.
  • Sp 11 denotes -(CFh , where n is an integer from 1 to 15, wherein one or more -CFI 2 - groups may be replaced by -CO-, preferably an uneven integer, more preferably 7, 9, 11 or 13, Further preferred compounds of formula I are those wherein -X 1 1 -Sp 1 1 -Xi2.
  • L denotes each and independently in each occurrence F, Cl,
  • r denotes an integer between 0 and 4, preferably 0, 1 or 2
  • R 1 1 denotes an alkyl or alkoxy radical, which may be straight chain or branched having 2, 3, 4, 5, 6, 7 or 8 carbon atoms
  • R 12 denotes CN, NO 2 , F, OCFI3, OCN, COR x , COOR x or a mono- oligo- or polyfluorinated alkyl or alkoxy group with 1 to 4 C atoms, preferably F,
  • R x is optionally fluorinated alkyl with 1 to 4, preferably 1 to 3 C atoms, and
  • n denotes 7, 9, 1 1 or 13.
  • R 1 1 denotes alkyl, which may be straight chain or branched
  • R 12 denotes CN, F, CF3 or OCF3, preferably F, CF3 or OCF3, more preferably F, and n denotes 7, 9 or 1 1 .
  • Preferred compounds of formula II are selected from compounds in which the groups (-A 21 -A 22 -) and (-A 23 -A 24 -) are each and independently selected from the following groups
  • Phe in these groups is 1 ,4-phenylene
  • PheL is a 1 ,4-phenylene group which is substituted by 1 to 4
  • L is preferably F, Cl, CN, OH, NO2 or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, OH, NO2, CH3, C2H5, OCHs, OC2H5, COCH3, COC2H5, COOCHs, COOC2H5, CFs, OCF3, OCHF2, OC2F5, in particular F, Cl, CN, CH3, C2H5, OCH3, COCH3 and OCF3, most preferably F, Cl, CH3, OCH3 and COCHs and
  • Cyc is 1 ,4-cyclohexylene.
  • n denotes an integer from 1 to 15, preferably an odd (i.e.
  • Preferred compounds of formula III are selected from compounds in which c denotes 0 and the group (-A 31 -A 32 -) is selected from the groups MG1 to MG4 as given above.
  • Phe, PheL an L have one of the meanings given above for the groups MG- 1 to MG-4.
  • Especially preferred compounds of formula III are selected from the group of compounds of the following formulae,
  • Preferred compounds of formula IV are selected from compounds in which the groups (-A 41 -A 42 -) and (-A 43 -A 44 -) are each and independently selected from the groups of MG1 to MG4 as given above.
  • Especially preferred compounds of formula IV are selected from the group of compounds of the following formulae: symmetrical ones (IVa and IVb):
  • a 51 is selected from the following group of formulae Va’ to Vf and the mirror images of formulae Va’, Vd’ and Ve’
  • R 51 and R 52 in formula V are selected of H, F, Cl, CN, NO2,
  • Preferred compounds of formula V are selected from the group of compounds of formulae VA to VD, preferably of formulae VA and/or VC, most preferably of formula VC,
  • LG 51 is Z 51 -(CH 2 ) Z -Z 52 ,
  • (F)i denotes F. and the other parameters have the respective meanings given above including the preferred meanings.
  • Z 51 -(CH 2 ) z -Z 52 denotes -0-C0-(CH 2 ) n -C0-0-, -0-(CH 2 ) n -0- or - (CH 2 ) n -, more preferably -0-C0-(CFI 2 ) n -C0-0-, wherein n denotes 3, 5, 7 or 9,
  • Particularly preferred compounds of formula VA are selected from the group of compounds of formulae VA-1 to VA-3
  • Particularly preferred compounds of formula VB are selected from the group of compounds of formulae VB-1 to VB-3
  • Compounds of formula VC are very much preferred. And of these particularly preferred compounds are selected from the group of compounds of formulae VC-1 to VC-3
  • Preferred compounds of formula VI are selected from compounds in which the groups (-A 61 -A 62 -) and (-A 63 -A 64 -) are each and independently selected from the groups of MG1 to MG4 as given above.
  • Preferred compounds of formula VII are selected from compounds in which at least one of the groups -A 71 -Z 71 -A 72 -(Z 72 -A 73 ),-,
  • L is in each occurrence independently of each other preferably F, Cl, CN or an optionally fluorinated alkyl, alkoxy or alkanoyl group with 1 to 7 C atoms, very preferably F, Cl, CN, CFb, C2FI5, OCFI3, OC2FI5, COCFI3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, in particular F, Cl, CN, CFI3, C2FI5, OCFI3, COCFI3 and OCF3, most preferably F, Cl, CFI3, OCH3 and COCH3 and r is in each occurrence independently of each other 0, 1 , 2, 3 or 4, preferably 0, 1 or 2.
  • L is preferably F, Cl, CH3, OCH3 and COCH3 .
  • i and k both denote 1 , more preferably one of i and k denotes 0 and the other 1 , most preferably i and k both denote 0.
  • Especially preferred compounds of formula VII are selected from the group of compounds of the following formulae
  • R 71 and R 72 each and independently denote F or CN, preferably F.
  • the medium according to the invention comprises one or more compounds of formula Y-5
  • R Y1 has the meaning defined above for formulae Y-1 to Y-4, and
  • R Y3 denotes alkyl or alkenyl having up to 15 C atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, and preferably
  • R Y1 denotes an unsubstituted alkyl radical having 1 to 7 C
  • R Y3 denotes an unsubstituted alkyl radical having 1 to 7 C atoms, particularly preferably having 2 to 5 C atoms.
  • the media according to the invention comprise one or more compounds of the formula Y-1 , preferably one or more compounds selected from the group of the compounds of the formulae Y-1 -1 and Y-1 -2,
  • R Y1 on each occurrence denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2 to 5 C atoms, or
  • alkenyl radical having 2 to 7 C atoms, preferably a straight-chain alkenyl radical, particularly preferably having 2 to 5 C atoms,
  • R Y2 on each occurrence denotes an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms, or an unsubstituted alkoxy radical having 1 to 6 C atoms, preferably having 2, 3 or 4 C atoms.
  • the media according to the invention comprise one or more compounds of the formula Y-2, preferably one or more compounds selected from the group of compounds of the formulae Y-2-1 and Y-2-2,
  • R Y1 denotes an alkyl radical having 2 to 5 C atoms, preferably having 3 to 5 C atoms, and
  • R Y2 denotes an alkyl or alkoxy radical having 2 to 5 C atoms, preferably an alkoxy radical having 2 to 4 C atoms, or an alkenyloxy radical having 2 to 4 C atoms.
  • the media according to the invention comprise one or more compounds of the formula Y-3, preferably one or more compounds selected from the group of the compounds of the formulae Y-3-1 and Y-3-2, very particularly preferably of the formula Y-3-2, in which the parameters have the meaning given above formula Y-3 and preferably
  • R Y1 denotes an alkyl radical having 2 to 5 C atoms, preferably having 3 to 5 C atoms, and
  • R Y2 denotes an alkyl or alkoxy radical having 2 to 5 C atoms, preferably an alkoxy radical having 2 to 4 C atoms, or an alkenyloxy radical having 2 to 4 C atoms.
  • the medium comprises one or more compounds of the formula Y-4, preferably of the formula Y-4-1 ,
  • alkyl and alkyl independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms.
  • the liquid-crystal medium according to the invention comprises one or more compounds selected from the group of compounds of the formulae B and BS, preferably BS, in which
  • R B1 , R B2 independently of one another, denote an unsubstituted alkyl radical having 1 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2 to 5 C atoms, or an unsubstituted alkenyl or alkoxy radical having 2 to 7 C atoms, particularly preferably having 2 to 5 C atoms, where preferably at least one of the radicals R B1 and R B2 denotes alkoxy.
  • the medium comprises one or more compounds of compound BS, preferably selected from the compounds of the formula BS-
  • alkoxy and alkoxy denote n-alkyloxy having 2 to 5 C atoms.
  • the medium further comprises one or more compounds selected from the group of compounds of the formulae C and P in which
  • R C1 denotes an unsubstituted alkyl radical having 1 to 7 C
  • R C2 denotes an unsubstituted alkyl radical having 1 to 7 C
  • R P1 and R P2 independently of one another, have one of the meanings given for R 21 and R 22 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 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, preferably having 2 to 4 C atoms, preferably alkenyloxy,
  • (i + j) preferably denotes 0 or 1.
  • the medium comprises one or more compounds of the formula C, preferably selected from the group of the compounds of the formulae C-1 to C-4, preferably selected from the group of the compounds of the formulae C and C-2,
  • 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, prefer- ably having 2 to 4 C atoms, particularly preferably 2 C atoms
  • alkenyl’ denotes an alkenyl radical having 2 to 5 C atoms, prefer- ably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms
  • alkoxy denotes alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.
  • the media according to the inven- tion comprise one or more compounds of the formula C-1 and/or one or more compounds of the formula C-2.
  • the medium comprises one or more compounds of the formula C, selected from the group of the compounds of the formulae C-3 and C-4,
  • the medium comprises one or more compounds of the formula P selected from the group of the compounds of the formulae P-1 to P-10, preferably selected from the group of the corn- pounds of the formulae P-1 to P-5,
  • Y p denotes H or F, and preferably
  • R P1 denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to
  • R P2 denotes alkyl having 1 to 7 C atoms, alkenyl having 2 to 7
  • C atoms or alkoxy having 1 to 6 C atoms preferably alkyl or alkenyl, particularly preferably alkenyl.
  • the medium comprises one or more compounds of the formula P-1 selected from the group of the compounds of the formulae P-1 a and P-1 b, preferably of the formula P-1 b,
  • the medium comprises one or more compounds of the formula P-3 selected from the group of the compounds of the formulae P-3a and P-3b,
  • alkyl and alkyl independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, and alkenyl denotes alkenyl having 2 to 7 C atoms, preferably having 2 to 5 C atoms.
  • the medium comprises one or more compounds of the formula P-4 selected from the group of the compounds of the formulae P-4a and P-4b,
  • alkyl and alkyl independently of one another, denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms.
  • the present invention relates to a process for the stabilisation of a liquid-crystalline medium which comprises one or more compounds selected from the group of the compounds of the formulae Y-1 to Y-4 and/or one or more compounds of the formula C and/or one or more corn- pounds of the formula P, characterised in that one or more compounds of the formula I are added to the medium.
  • liquid-crystalline media according to the resent invention may corn- prise one or more chiral compounds.
  • the liquid- crystalline media comprise one or more compounds of the formula
  • n denotes 0, 1 , 2, 3, 4, 5 or 6, preferably 2 or 4, particularly pref- erably 2, preferably in a concentration of 0.1 to 5%, particularly preferably of 0.2 to 1 %.
  • liquid- crystalline media comprise one or more compounds of the formula Y-5-1
  • n denotes 0, 1 , 2, 3, 4, 5 or 6, preferably 1 , 2, 3 or 4, particularly preferably 1
  • m denotes 1 , 2, 3 or 4, preferably 1 , 2, or 3, particularly preferably 3, in a concentration of 0.1 to 5%, particularly preferably of 0.2 to 2%.
  • the liquid-crystalline medium has a birefringence of 0.060 or more, particularly preferably 0.070 or more.
  • the liquid-crystalline medium has a birefringence of 0.130 or less, particularly preferably 0.120 or less.
  • the liquid-crystalline medium has a birefringence in the range of 0.090 to 0.120, preferably of 0.095 to 0.115, particularly preferably of 0.100 to 0.110. iv.
  • the liquid-crystalline medium has a negative dielectric anisotropy having an absolute value of 2.0 or more, particularly preferably 2.5 or more.
  • the liquid-crystalline medium has a negative dielectric anisotropy having an absolute value of 7.0 or less, particularly preferably 6.5 or less.
  • the liquid-crystalline medium has a negative dielectric anisotropy having an absolute value in the range of 2.5 to 6.5, preferably of 3.0 to 6.0, particularly preferably of 3.0 to 5.5. vii.
  • the liquid-crystalline medium comprises one or more particularly pre- ferred compounds of the formula C selected from the sub-formulae given below: in which alkyl has the meaning given above and preferably, in each case independently of one another, denotes alkyl having 1 to 6, pref- erably having 2 to 5, C atoms and particularly preferably n-alkyl. viii.
  • the total concentration of the compounds of the formula C in the mix- ture as a whole is 5% or more, preferably 15% or more, and is pref- erably in the range of from 10% to 60%, particularly preferably in the range of from 10% to 55%, and very particularly preferably in the range of from 15% to 50%. ix.
  • the liquid-crystalline medium comprises one or more compounds of the formula C selected from the group of the compounds of the fol lowing formulae: CC-n-V and/or CC-n-Vm, particularly preferably CC-3-V, preferably in a concentration of 55% or less, particularly preferably 50% or less, and optionally additionally CC-3-V1 , preferably in a concentration of 15% or less, and/or CC-4-V, preferably in a concentration 20% or less, particularly preferably 10% or less.
  • the total concentration of the compounds B and/or BS in the mixture as a whole is in the range of from 1 % to 20%, preferably from 2.5% to 17.5%, particularly preferably from 4% to 15%.
  • xi The total concentration of the compounds of the formula CC-3-V in the mixture as a whole is 10% or more, preferably 15% or more. xii.
  • optionally B and/or BS and/or Y-5 in the mixture as a whole is in the range of from 10% to 95%, preferably from 40% to 90% and particularly preferable from 50% to 85%.
  • the liquid-crystalline medium comprises one or more compounds of the formula C, preferably of the formulae C-1 and/or C-2, preferably in a total concentration of 20% or more, in particular of 25% or more, and very particularly preferably in the range of from 30% to 45%.
  • the medium comprises one two or three compounds selected from the group of compounds of the formulae I, II, III, IV, V, VI, and VII., preferably I, II, VI and VII, particularly of formula 1-4, lla, VI-6 and VII-21.
  • the total concentration of the compounds of the formulae I, II, III, IV, V, VI, and VII in the medium is in the range of from 0.1 % to 10%, preferably from 0.5% to 8% and particularly preferably from 1 % to 5%.
  • the medium according to the invention particularly preferably comprises one or more compounds of the formula Y-1 in a total concentration in the range of from 5% to 30% and/or one or more compounds of the formula Y-2 in a total concentration in the range of from 3% to 30% and/or one or more compounds of the formula Y-3 in a total concentration in the range of from 5% to 30% and/or one or more compounds of the formula Y-4 in a total concentration in the range of from 1 % to 30%;
  • the liquid-crystal mixture preferably has a nematic phase range having a width of at least 80 K and a flow viscosity V20 of at most 30 mm 2 ⁇ s 1 at 20°C.
  • the liquid-crystal mixture according to the invention has a De of -0.5 to -8.0, in particular -1.5 to -6.0, and very particularly preferably -2.0 to -5.0, where De denotes the dielectric anisotropy.
  • the rotational viscosity gi is preferably 200 mPa s or less, in particular 150 mPa s or less, particularly preferably 120 mPa s or less.
  • the mixtures according to the invention are suitable for all VA-TFT applica- tions, such as, for example, VAN, MVA, (S)-PVA and ASV. Furthermore, they are particularly suitable for IPS (in-plane switching), FFS (fringe-field switching) and PALC applications having negative De.
  • the liquid-crystalline media according to the invention preferably comprise 4 to 15, in particular 5 to 12, and particularly preferably 10 or less, corn- pounds. These are preferably selected from the group of the compounds of the formulae I, II, III, IV, V, VI, VII, Y-1 , Y-2, Y-3, Y-4, Y-5 and/or C and/or P.
  • the liquid-crystalline media according to the invention may optionally also comprise more than 18 compounds. In this case, they preferably comprise 18 to 25 compounds.
  • the media according to the invention may optionally also comprise a di- electrically positive component, the total concentration of which is preferably 10% or less, based on the entire medium.
  • a di- electrically positive component the total concentration of which is preferably 10% or less, based on the entire medium.
  • the medium it is advantageous for the medium to have a nematic phase from in each case at least -20°C or less to 70°C or more, particularly preferably from -30°C or less to 80°C or more, very particularly preferably from -40°C or less to 85°C or more and most preferably from -40°C or less to 90°C or more.
  • the expression "have a nematic phase” here means on the one hand that no smectic phase and no crystallisation is observed at low temperatures at the corresponding temperature and on the other hand that no clearing occurs on heating from of the nematic phase.
  • the investigation at low tem- peratures is carried out in a flow viscometer at the corresponding tempera- ture and checked by storage in test cells having a cell thickness corre- sponding to the electro-optical application 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 medium is regarded as stable at this temperature. At temperatures of -30°C and -40°C, the corresponding times are 500 h and 250 h respectively.
  • the liquid-crystal media according to the invention have relatively low val- ues for the threshold voltage (Vo) in the range of from 1.4 V to 2.5 V, preferably from 1.5 V to 2.2 V, particularly preferably from 1.6 V to 2.0 V.
  • Vo threshold voltage
  • liquid-crystal media according to the invention have high values for the VHR in liquid-crystal cells.
  • liquid-crystal media having a low addressing voltage or thresh- old voltage here have a lower VHR than those having a higher addressing voltage or threshold voltage, and vice versa.
  • the individual compounds are generally em- ployed in the mixtures in concentrations in each case from 1 % or more to 30% or less, preferably from 2% or more to 30% or less and particularly preferably from 3% or more to 16% or less.
  • the liquid-crystalline media according to the invention comprise one or more compounds selected from the group of compounds of the formulae I, II, III, IV, V, VI, VII, one or more compounds of the formula C, preferably selected from the group of the compounds of the formulae CC-n-V and CC-n-Vm, preferably CC-3-V, CC-3-V1 , CC-4-V and CC-5-V, particularly preferably selected from the group of the compounds CC-3-V, CC-3-V1 and CC-4-V, very par- ticularly preferably the compound CC-3-V, and optionally additionally the compound(s) CC-4-V and/or CC-3-V1 , one or more compounds of the formula Y-1 -1 , preferably of the formula CY-n-Om, selected from the group of the compounds of the formulae CY-3-02, CY-3-04, CY-5-02 and CY-5-04, one or more compounds of the formula Y-1 -2, preferably selected from the group of the
  • the expression “dielectrically positive corn- pounds” means compounds having a De of > 1.5
  • the expression “dielectri- cally neutral compounds” means those where -1.5 ⁇ De ⁇ 1.5
  • the ex- pression "dielectrically negative compounds” means those where De ⁇ -1.5.
  • the dielectric anisotropy of the compounds is determined here by dissolv- ing 10% of the compounds in a liquid-crystalline host and determining the capacitance of the resultant mixture in each case in at least one test cell having a cell thickness of 20 pm 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.
  • the host mixture used for dielectrically positive and dielectrically neutral compounds is ZLI-4792 and that used for dielectrically negative corn- pounds is ZLI-2857, both from Merck KGaA, Germany.
  • the values for the respective compounds to be investigated are obtained from the change in the dielectric constant of the host mixture after addition of the compound to be investigated and extrapolation to 100% of the compound employed.
  • the compound to be investigated is dissolved in the host mixture in an amount of 10%. If the solubility of the substance is too low for this purpose, the concentration is halved in steps until the investigation can be carried out at the desired temperature.
  • the liquid-crystal media according to the invention may, if necessary, also comprise further additives, such as, for example, stabilisers and/or pleo- chroic dyes and/or chiral dopants in the usual amounts.
  • the amount of these additives employed is preferably in total 0% or more to 10% or less, based on the amount of the entire mixture, particularly preferably 0.1 % or more to 6% or less.
  • the concentration of the individual compounds em- ployed is preferably 0.1 % or more to 3% or less. The concentration of these and similar additives is generally not taken into account when speci- fying the concentrations and concentration ranges of the liquid-crystal compounds in the liquid-crystal media.
  • the liquid-crystal media according to the inven- tion comprise a polymer precursor which comprises one or more reactive compounds, preferably reactive mesogens, and, if necessary, also further additives, such as, for example, polymerisation initiators and/or polymeri- sation moderators, in the usual amounts.
  • the amount of these additives employed is in total 0% or more to 10% or less, based on the amount of the entire mixture, preferably 0.1 % or more to 2% or less.
  • the concentra- tion of these and similar additives is not taken into account when specifying the concentrations and concentration ranges of the liquid-crystal com- pounds in the liquid-crystal media.
  • compositions consist of a plurality of compounds, preferably 3 or more to 30 or fewer, particularly preferably 6 or more to 20 or fewer and very particularly preferably 10 or more to 16 or fewer compounds, which are mixed in a conventional manner.
  • the desired amount of the components used in lesser amount is dissolved in the components making up the principal constituent of the mixture. This is advantageously carried out at elevated temperature. If the selected temperature is above the clear- ing point of the principal constituent, completion of the dissolution operation is particularly easy to observe.
  • the mixtures according to the invention exhibit very broad nematic phase ranges having clearing points of 65°C or more, very favourable values for the capacitive threshold, relatively high values for the holding ratio and at the same time very good low-temperature stabilities at -30°C and -40°C. Furthermore, the mixtures according to the invention are distinguished by low rotational viscosities gi. It goes without saying to the person skilled in the art that the media accord- ing to the invention for use in VA, IPS, FFS or PALC displays may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes.
  • the structure of the liquid-crystal displays according to the invention corre- sponds to the usual geometry, as described, for example, in
  • liquid-crystal phases according to the invention can be modified by means of suitable additives in such a way that they can be employed in any type of, for example, ECB, VAN, IPS, GH or ASM-VA LCD display that has been disclosed to date.
  • Table E below indicates possible dopants which can be added to the mix- tures according to the invention. If the mixtures comprise one or more dopants, it is (they are) employed in amounts of 0.01 to 4%, preferably 0.1 to 1.0%.
  • Stabilisers which can be added, for example, to the mixtures according to the invention, preferably in amounts of 0.01 to 6%, in particular 0.1 to 3%, are shown below in Table F.
  • threshold voltage relates to the capa- citive threshold (Vo), also known as the Freedericks threshold, unless explicitly indicated otherwise.
  • the threshold voltages are determined using test cells produced at Merck.
  • the test cells for the determination of De have a cell thickness of approximately 20 pm.
  • the electrode is a circular ITO electrode having an area of 1.13 cm 2 and a guard ring.
  • the orientation layers are SE-1211 from Nissan Chemicals, Japan, for homeotropic orientation (e
  • the capacitances are determined using a Solatron 1260 frequency response analyser using a sine wave with a voltage of 0.3 V rm s.
  • the light used in the electro-optical measurements is white light.
  • a chiral dopant is not added to the liquid- crystal mixtures used, but the latter are also particularly suitable for appli- cations in which doping of this type is necessary.
  • the VHR is determined in test cells produced at Merck Japan.
  • the test cells have alkali-free glass substrates and are provided with polyimide alignment layers with a layer thickness of 50 nm, which result in planar alignment of the liquid crystals.
  • the layer gap is a uniform 3.0 pm or 6.0 pm.
  • the surface area of the transparent ITO electrodes is 1 cm 2 .
  • VHR is determined at 20°C (VHR20) and after 5 minutes in an oven at 100°C (VHR100) in a commercially available instrument from Autronic Melchers, Germany.
  • the voltage used has a frequency of in a range from 1 Hz to 60 Hz, unless indicated more pre- cisely.
  • the stability to UV irradiation is investigated in a "Suntest CPS", a com-fural instrument from Heraeus, Germany.
  • the sealed test cells are irra- diated for between 30 min and 2.0 hours, unless explicitly indicated, with- out additional heating.
  • the irradiation power in the wavelength range from 300 nm to 800 nm is 765 W/m 2 V.
  • a UV "cut-off" filter having an edge wavelength of 310 nm is used in order to simulate the so-called window glass mode.
  • at least four test cells are investigated for each condition, and the respective results are indicated as averages of the corresponding individual measurements.
  • AVHR voltage holding ratio
  • the rotational viscosity is determined using the rotating permanent magnet method and the flow viscosity in a modified Ubbelohde viscometer.
  • the rotational viscosity values determined at 20°C are 161 mPa s, 133 mPa s and 186 mPa s respec- tively, and the flow viscosity values (v) are 21 mm 2 -s 1 , 14 mm 2 -s 1 and 27 mm 2 -s 1 respectively.
  • Flicker is defined as the difference between the maximum and the minimum transmittance divided by the average transmittance for a given frequency period, i.e. from the time of applying the positive polarity to the end of applying the negative polarity of the electric field.
  • Flicker is measured by using standard UB-FFS electro-optical (e/o) test cells, described above, applying an A/C voltage of L16, L127, L255 and/or V100, where L refers to the corresponding gray level and V100 to the voltage corresponding to 100% transmittance with 1 Flz to 30 Flz at a temperature of 20°C, 25 °C and or 60 °C.
  • D/C offset controlled adaptively in order to get the minimum flicker value with typical values of the D/C offset between 0 mV and +- 100 mV.
  • V100 L255 which is the voltage maximum of the voltage-transmittance curve (V/T curve).
  • Gray level flicker is measured at a gray level of L127.
  • the following symbols are used, unless explicitly indicated otherwise:
  • 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 D shows illustra tive structures of compounds together with their respective abbreviations.
  • n and m are each integers, and the three dots are place- holders for other abbreviations from this table.
  • Table D shows exemplary compounds of formulae I to VII.
  • n is an integer selected from 3 and 5 to 15, preferably from 3, 5, 7 and 9, unless explicitly defined otherwise.
  • N-PGI-S-n-S-GP-N wherein n is an integer from 12 to 15, preferably an even integer.
  • m-CPGI-O-n-O-GPP-k wherein m and k are independently of each other an integer from 1 to 9 preferably from 1 to 7, more preferably from 3 to 5 and n is an integer from 1 to 15, preferably an odd integer from 3 to 9.
  • Table F shows chiral dopants which are preferably employed in the mix- tures according to the invention.
  • the media according to the invention comprise one or more compounds selected from the group of the compounds from Table F.
  • Table G shows stabilisers which can be employed in the mixtures accord- ing to the invention in addition to the compounds of the formula I.
  • the parameter n here denotes an integer in the range from 1 to 12.
  • the phenol derivatives shown can be employed as additional stabilisers since they act as antioxidants.
  • Table G Stabilisers which can be added, for example, to the mixtures according to the invention in amounts of 0-10% by weight are mentioned below.
  • n 1 , 2, 3, 4, 5, 6 or 7
  • the media according to the invention comprise one or more compounds selected from the group of the compounds from Table G. Examples
  • Example Mixtures are prepared using the following compounds of the
  • the comparative mixture example C-1 which, apart from the bimesogen, comprises the same compounds and has the same birefringence as the Mixture Examples M1 to M4, is prepared as follows:
  • All mixtures M1 to M4 according to the invention show advantageously low flicker resulting in superior image qualities of a displays comprising these mixtures.
  • All mixtures M1 to M4 according to the invention show less flicker compared to the mixture C1 which does not contain a bimesogenic additive.

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  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Liquid Crystal Substances (AREA)

Abstract

La présente invention concerne des milieux cristallins liquides comprenant un ou plusieurs composés ayant les formules (Y-1, Y-2, Y-3, Y-4) dans lesquelles les groupes et paramètres qui apparaissent ont les significations définies dans la revendication 1, et un bimésogène tel que défini dans la revendication 1, l'utilisation de ces milieux cristallins liquides dans des affichages à cristaux liquides, et ces affichages à cristaux liquides, en particulier les affichages à cristaux liquides qui utilisent l'effet de commutation de champ de franges (FFS) avec des cristaux liquides diélectriquement négatifs.
PCT/EP2019/056741 2018-03-22 2019-03-19 Milieu cristallin liquide WO2019179962A1 (fr)

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Cited By (3)

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Publication number Priority date Publication date Assignee Title
CN113913195A (zh) * 2020-07-09 2022-01-11 Dic株式会社 液晶组合物及液晶显示元件
WO2022088916A1 (fr) * 2020-11-02 2022-05-05 北京八亿时空液晶科技股份有限公司 Composition de cristaux liquides contenant du pyrane et du terphényle et utilisation associée
EP4159829A4 (fr) * 2020-05-29 2024-06-19 Smart Liquid Crystal Technologies Co., Ltd. Composition de cristaux liquides et son dispositif de gradation

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP4159829A4 (fr) * 2020-05-29 2024-06-19 Smart Liquid Crystal Technologies Co., Ltd. Composition de cristaux liquides et son dispositif de gradation
CN113913195A (zh) * 2020-07-09 2022-01-11 Dic株式会社 液晶组合物及液晶显示元件
WO2022088916A1 (fr) * 2020-11-02 2022-05-05 北京八亿时空液晶科技股份有限公司 Composition de cristaux liquides contenant du pyrane et du terphényle et utilisation associée
CN114437735A (zh) * 2020-11-02 2022-05-06 北京八亿时空液晶科技股份有限公司 一种含吡喃与三联苯的液晶组合物及其应用
CN114437735B (zh) * 2020-11-02 2023-05-12 北京八亿时空液晶科技股份有限公司 一种含吡喃与三联苯的液晶组合物及其应用

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