Liquid crystal mixture and liquid crystal display

Abstract

The present invention relates to liquid crystal mixtures comprising a photoalignment component A) comprising one or more photoreactive mesogens of the formula I, wherein R 11 , R 21 , A 11 , A, Z, X 11 , X 21 , Y 11 , Y 12 、Sp 11 、Sp 21 , o and p have one of the meanings given in claim 1, the liquid crystal component B) comprises one or more nematic compounds, and the polymerizable component C) comprises one or more polymerizable compounds of formula P, P a ‑Sp a ‑(A p )‑R b P where P a , R b 、Sp a and A p has one of the meanings given in claim 1. Furthermore, the invention relates to a process for preparing such an LC medium, to the use of such a medium in an LC device, and to an LC device comprising an LC medium according to the invention. The invention further relates to a process for producing such a liquid-crystal display and to the use of a liquid-crystal mixture according to the invention for producing such a liquid-crystal display.

Description

Technical Field

[0001] The present invention relates to liquid-crystal mixtures comprising a photoalignment component A) comprising one or more photoreactive mesogens of the formula I,

[0002]

[0003] Where R 11 , R 21 , A 11 , A, Z, X 11 , X 21 , Y 11 , Y 12 、Sp 11 、Sp 21 , o and p have one of the meanings given in claim 1,

[0004] a liquid crystal component B) comprising one or more nematic compounds, and

[0005] The polymerizable component C) comprises one or more polymerizable compounds of formula P,

[0006] P a -Sp a -(A p )-R b P

[0007] Where P a , R b 、Sp a and A p has one of the meanings given in claim 1.

[0008] Furthermore, the present invention relates to a process for preparing such an LC medium, the use of such a medium in an LC device, and an LC device comprising an LC medium according to the invention. The present invention further relates to a process for producing such a liquid crystal display and the use of a liquid crystal mixture according to the invention for producing such a liquid crystal display. Background Art

[0009] For the purpose of information display, liquid-crystalline media have been used in electro-optical displays for decades. The liquid-crystalline displays used currently are generally those of the TN (“twisted nematic”) type. However, these have the disadvantage of a strong viewing angle dependence of the contrast.

[0010] In addition, so-called VA (“vertically aligned”) displays are known, which have a wider viewing angle. The LC cell of a VA display contains an LC medium layer between two transparent electrodes, wherein the LC medium generally has a negative dielectric (DC) anisotropy value. In the switched-off state, the molecules of the LC layer are aligned perpendicularly to the electrode surfaces (homeotropic) or have an inclined homeotropic alignment. When a voltage is applied to the two electrodes, the LC molecules parallel to the electrode surfaces realign. In addition, so-called IPS (“in-plane switching”) displays and later FFS (“fringe field switching”) displays have been reported (see in particular SH Jung et al., Jpn. J. Appl. Phys., Vol. 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 not structured. This generates a strong so-called “fringe field”, i.e. a strong electric field close to the edges of the electrodes, and an electric field with both a strong vertical component and a strong horizontal component throughout the cell. 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 polyimide, which provides a planar alignment for the molecules of the LC medium.

[0011] Furthermore, FFS displays have been disclosed (see SH Lee et al., Appl. Phys. Lett. 73 (20), 1998, 2882-2883 and SH Lee et al., Liquid Crystals 39 (9), 2012, 1141-1148) which have similar electrode designs and layer thicknesses as FFS displays, but comprise layers of LC media with negative dielectric anisotropy instead of LC media with positive dielectric anisotropy. LC media with negative dielectric anisotropy show more favorable director orientations with less tilted and more twisted orientations than LC media with positive dielectric anisotropy, as a result of which these displays have higher transmittance.

[0012] Another development is the so-called PS (polymer-stabilized) or PSA (polymer-stabilized aligned) displays, for which the term “polymer-stabilized” is also occasionally used. PSA displays are characterized by a shortened response time without significant adverse effects on other parameters, such as, in particular, the viewing angle dependence of the advantageous contrast.

[0013] In these displays, small amounts (e.g. 0.3 wt. %, typically <1 wt. %) of one or more polymerizable compounds are added to the LC medium and, after introduction into the LC cell, polymerized or crosslinked in situ between the electrodes with or without applied voltage, typically by UV photopolymerization. The addition of polymerizable mesogens or liquid crystal compounds (also called reactive mesogens or "RMs") to the LC mixture has proven to be particularly suitable. PSA technology has hitherto been used primarily for LC media with negative dielectric anisotropy.

[0014] Unless otherwise indicated, the term "PSA" is used hereinafter as a representative of both PS displays and PSA displays.

[0015] At the same time, the PSA principle is being used in a variety of classical LC displays. Thus, for example, PSA-VA, PSA-OCB, PSA-IPS, PSA-FFS and PSA-TN displays are known. Preferably, the polymerization of the polymerizable compound is carried out under applied voltage in the case of PSA-VA and PSA-OCB displays, and under applied or unapplied voltage in the case of PSA-IPS displays. As can be shown in the test box, the PS (A) method produces a "pre-tilt" in the box. In the case of PSA-OCB displays, for example, the curved structure can be stabilized so that the compensation voltage is unnecessary or can be reduced. In the case of PSA-VA displays, the pre-tilt has a positive effect on the response time. Standard MVA or PVA pixel and electrode layouts can be used for PSA-VA displays. However, in addition, it is also possible to manage, for example, only with one structured electrode side and without protrusions, which significantly simplifies the production and at the same time produces a very good contrast while producing a very good light transmittance.

[0016] PSA-VA displays are described, for example, in JP 10-036847 A, EP 1 170 626 A2, US 6,861,107, US 7,169,449, US 2004 / 0191428 A1, US 2006 / 0066793 A1 and US 2006 / 0103804 A1. PSA-OCB displays are described, for example, in T.-J-Chen et al., Jpn. J. Appl. Phys. 45, 2006, 2702-2704 and SH Kim, L.-C-Chien, Jpn. J. Appl. Phys. 43, 2004, 7643-7647. PSA-IPS displays are described, for example, in US 6,177,972 and Appl. Phys. Lett. 1999, 75 (21), 3264. PSA-TN displays are described, for example, in Optics Express 2004, 12 (7), 1221. PSA-VA-IPS displays are described, for example, in WO 2010 / 089092 A1.

[0017] As with conventional LC displays described above, PSA displays can be operated as active matrix or passive matrix displays. In the case of active matrix displays, the individual pixels are typically addressed by integrated non-linear active elements such as transistors (e.g. thin film transistors or "TFTs"), while in the case of passive matrix displays, the individual pixels are typically addressed by multiplexing methods, both of which are known from the prior art.

[0018] In the prior art, polymerizable compounds such as those of the following formula are used for PSA-VA:

[0019]

[0020] wherein P represents a polymerizable group, typically an acrylate group or a methacrylate group, as described, for example, in US 7,169,449.

[0021] Under the polymer layer inducing the above mentioned pretilt, the orientation layer (usually polyimide) provides the initial alignment of the liquid crystal without taking into account the polymer stabilization step of the production process.

[0022] The efforts directed to the manufacture of polyimide layers, the processing of the layers and the improvement of the bumps or polymer layers are relatively large. Therefore, a simplified technology would be needed which would reduce the manufacturing costs on the one hand and help to optimize the image quality (viewing angle dependence, contrast, response time) on the other hand.

[0023] Rubbed polyimide has long been used to align liquid crystals. The rubbing method causes a variety of problems: non-uniformity, contamination, electrostatic discharge problems, residues, etc.

[0024] Photoalignment is a technique for achieving friction-free alignment of liquid crystals (LCs) by replacing friction with a light-induced orientation ordering of the alignment surface. This can be achieved via the mechanisms of photolysis, photodimerization and photoisomerization with the aid of polarized light (NA Clark et al., Langmuir 2010, 26 (22), 17482-17488 and references cited therein). However, a suitably derivatized polyimide layer comprising photoreactive groups is still required. Another improvement would be to avoid the use of polyimide altogether. For VA displays, this is achieved by adding a self-aligning agent to the LC which induces in situ homeotropic alignment via a self-assembly mechanism as disclosed in WO 2012 / 104008 and WO 2012 / 038026.

[0025] NA Clark et al., Langmuir 2010, 26 (22), 17482-17488 have shown that it is possible to self-assemble compounds of the following structure onto a substrate to obtain a monolayer that can be photoaligned to induce planar alignment of the liquid crystal.

[0026]

[0027] However, a separate step of self-assembly is required prior to fabrication of the LC cell, and the nature of the azo group results in reversibility of the alignment upon exposure to light.

[0028] Another functional group known to allow photo-alignment is phenylvinylcarbonyloxy (cinnamate). Photo-crosslinkable cinnamate is known from the prior art, for example from EP0763552, as disclosed in the following structure:

[0029]

[0030] From such compounds, polymers such as the following can be obtained

[0031]

[0032] This substance is used in a photoalignment method as disclosed in WO 99 / 49360 to obtain an alignment layer for liquid crystals. The alignment layer obtained by this method has the disadvantage that it provides a lower voltage holding ratio (VHR) compared to polyimides.

[0033] In WO 00 / 05189 polymerisable direactive mesogenic cinnamates are disclosed for use as, for example, optical retarders in polymerisable LC mixtures.

[0034]

[0035] In GB 2 306 470 A it is disclosed that structurally related compounds of the formula comprising two cinnamic acid moieties are used as components in liquid-crystalline polymer films.

[0036]

[0037] Such compounds have not been used or suggested for use as photoalignment agents.

[0038] Very similar compounds are disclosed in BMI van der Zande et al., Liquid Crystals, Vol. 33, No. 6, June 2006, 723-737 as patterning retarders in the field of liquid crystal polymers and have the following structure:

[0039]

[0040] WO 2017 / 102068 A1 discloses the same structure for the purpose of a polyimide-free planar photoalignment method.

[0041] In addition, MHLee et al. disclosed in Liquid Crystals (https: / / doi.org / 10.1080 / 02678292.2018.1441459) a method for non-polyimide-free surface photoalignment induced by a polymerizable liquid crystal containing a cinnamate group of the following formula:

[0042]

[0043] Therefore, there is a great need for new photoreactive mesogens that enable in situ photoalignment of liquid crystal mixtures, i.e., after assembly of the display, by photoalignment with linearly polarized light.

[0044] In addition to this requirement, the corresponding photoreactive mesogens should preferably provide liquid crystal displays having an advantageously high dark state and an advantageously high voltage holding ratio at the same time. Furthermore, the amount of photoreactive mesogens in the nematic LC medium should be as small as possible and their production should be obtainable by methods that are compatible with common mass production methods, for example with regard to advantageously short processing times. Summary of the invention

[0045] The objects of the present invention will be immediately apparent to those skilled in the art from the following detailed description.

[0046] Surprisingly, the inventors have found that one or more of the above-mentioned objects can be achieved by providing compounds according to claim 1 .

[0047] Terms and Definitions

[0048] Photoreactive groups according to the invention are functional groups of molecules which cause a change in the molecular geometry by bond rotation, skeletal rearrangement or atom or group transfer, or by dimerization upon irradiation with light of a suitable wavelength which can be absorbed by the molecule.

[0049] As used herein, the term "mesogenic group" is known to those skilled in the art and is described in the literature and refers to a group that substantially contributes to the generation of a liquid crystal (LC) phase in a low molecular weight or polymeric substance due to its anisotropy of attraction and repulsion interactions. A compound containing a mesogenic group (mesogenic compound) does not necessarily have an LC phase per se. A mesogenic compound may also exhibit LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod-shaped or disc-shaped units. Terms and definitions used in connection with mesogenic or LC compounds are given in Pure Appl. Chem. 2001, 73 (5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368.

[0050] The photoreactive mesogen according to the present invention is a mesogenic compound comprising one or more photoreactive groups.

[0051] Examples of photoreactive groups are -C=C- double bonds and azo groups (-N=N-).

[0052] Examples of molecular structures and substructures comprising such photoreactive groups are stilbene, (1,2-difluoro-2-phenyl-vinyl)-benzene, cinnamate, 4-phenylbut-3-en-2-one, chalcone, coumarin, chromone, pentalenone and azobenzene.

[0053] According to the present application, the term "linearly polarized light" refers to light that is at least partially linearly polarized. Preferably, the aligning light is linearly polarized with a degree of polarization greater than 5:1. The wavelength, intensity and energy of the linearly polarized light are selected depending on the photosensitivity of the photoalignable substance. Typically, the wavelength is in the UV-A, UV-B and / or UV-C range or in the visible light range. Preferably, the linearly polarized light comprises light with a wavelength of less than 450 nm, more preferably less than 420 nm, while the linearly polarized light preferably comprises light with a wavelength of greater than 280 nm, preferably greater than 320 nm, more preferably greater than 350 nm.

[0054] The term "organic group" means a carbon or hydrocarbon group.

[0055] The term "carbonyl" refers to a monovalent or polyvalent organic group containing at least one carbon atom, wherein it does not contain other atoms (such as, -C≡C-) or optionally contains one or more other atoms, such as N, O, S, P, Si, Se, As, Te or Ge (e.g., carbonyl, etc.). The term "hydrocarbyl" refers to a carbon group that additionally contains one or more H atoms and optionally one or more heteroatoms (such as, N, O, S, P, Si, Se, As, Te or Ge).

[0056] "Halogen" means F, Cl, Br or I.

[0057] The carbyl or hydrocarbon group may be a saturated or unsaturated group. An unsaturated group is, for example, an aryl, an alkenyl or an alkynyl group. The carbyl or hydrocarbon group having 3 or more atoms may be straight chain, branched and / or cyclic, and may also contain a spiro bond or a condensed ring.

[0058] The terms "alkyl," "aryl," "heteroaryl," and the like also encompass multivalent groups such as alkylene, arylene, heteroarylene, and the like.

[0059] The term "aryl" refers to an aromatic carbon group or a group derived therefrom. The term "heteroaryl" refers to an "aryl" as defined above containing one or more heteroatoms.

[0060] Preferred carbyl and hydrocarbyl groups are optionally substituted alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy groups having 1 to 40, preferably 1 to 25, particularly preferably 1 to 18 C atoms; optionally substituted aryl or aryloxy groups having 6 to 40, preferably 6 to 25 C atoms; or optionally substituted alkaryl, aralkyl, alkylaryloxy, arylalkoxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy groups having 6 to 40, preferably 6 to 25 C atoms.

[0061] Further preferred carbon and hydrocarbon groups are C1-C 40 Alkyl, C2-C 40 Alkenyl, C2-C 40 Alkynyl, C3-C 40 Allyl, C4-C 40 Alkyldiene, C4-C 40 Polyene, C6-C 40 Aryl, C6-C 40 Alkyl aryl, C6-C 40 Arylalkyl, C6-C 40 Alkyl aryloxy, C6-C 40 Arylalkoxy, C2-C 40 Heteroaryl, C4-C 40 Cycloalkyl, C4-C 40 Particularly preferred is C1-C22 Alkyl, C2-C 22 Alkenyl, C2-C 22 Alkynyl, C3-C 22 Allyl, C4-C 22 Alkyldiene, C6-C 12 Aryl, C6-C 20 Aralkyl and C2-C 20 Heteroaryl.

[0062] Other preferred carbon and hydrocarbon radicals are straight-chain, branched or cyclic alkyl radicals having 1 to 40, preferably 1 to 25, C atoms, which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN, and in which one or more non-adjacent CH2 groups may each be independently of one another by -C(R) in such a way that the O and / or S atoms are not directly connected to one another. z )=C(R z )-、-C≡C-、-N(R z )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- substitution.

[0063] R z Preferably it represents H, halogen, a straight-chain, branched or cycloalkyl chain having 1 to 25 C atoms, in which, in addition, one or more non-adjacent C atoms may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O-, and in which one or more H atoms may be replaced by fluorine, an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

[0064] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl and perfluorohexyl.

[0065] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl and cyclooctenyl.

[0066] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl and octynyl.

[0067] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, 2-methylbutoxy, n-pentoxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy and n-dodecyloxy.

[0068] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino and phenylamino.

[0069] Aryl and heteroaryl groups may be monocyclic or polycyclic, i.e. they may contain one ring (e.g. phenyl) or two or more rings, which may also be fused (e.g. naphthyl) or covalently bonded (e.g. biphenyl), or comprise a combination of fused and linked rings. Heteroaryl groups contain one or more heteroatoms, preferably selected from O, N, S and Se. Ring systems of this type may also contain independent non-conjugated units, as is the case, for example, in the fluorene basic structure.

[0070] Particularly preferred are mono-, bi- or tricyclic aryl radicals having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl radicals having 2 to 25 C atoms, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6- or 7-membered aryl and heteroaryl radicals, in which, in addition, one or more CH groups may be replaced by N, S or O in such a way that the O atoms and / or S atoms are not directly connected to one another.

[0071] Preferred aryl groups are derived from, for example, the following parent structures: benzene, biphenyl, terphenyl, [1,1':3',1"]terphenyl, naphthalene, anthracene, binaphthyl, phenanthrene, pyrene, dihydropyrene, Perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, etc.

[0072] 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-oxadiazole, 4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, a 6-membered ring such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine or a fused group such as indole, isoindole, indolizine, indazole, benzimidazole, benzoimidazole, triazole, purine, naphthimidazole, phenanthimidazole, pyridimidazole, pyrazimidazole, quinoxalinimidazole, benzoxazole, naphthimidazole, anthraxidazole, phenanthimidazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzisoquinoline, acridine, phenothiazine The heteroaryl group may also be substituted by an alkyl, alkoxy, sulfanyl, fluorine, fluorine, or other aryl or heteroaryl group.

[0073] (Non-aromatic) alicyclic and heterocyclic groups include both saturated rings, i.e. those containing only single bonds, and partially unsaturated rings, i.e. those which may also contain multiple bonds. The heterocyclic ring contains one or more heteroatoms, preferably selected from Si, O, N, S and Se.

[0074] (Non-aromatic) alicyclic groups and heterocyclic groups can be monocyclic, i.e. contain only one ring (e.g. cyclohexane), or polycyclic, i.e. contain multiple rings (e.g. decalin or bicyclooctane). Saturated groups are particularly preferred. In addition, mono-, bi- or tricyclic groups with 3-25 C atoms are preferred, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6-, 7- or 8-membered carbocyclic groups, wherein 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 CH2 groups may be replaced by-O- and / or-S-.

[0075] 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 condensed groups, such as tetralin, decalin, indane, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindan-2,5-diyl.

[0076] The aryl, heteroaryl, carbonyl and hydrocarbon groups optionally have one or more substituents, which are preferably selected from the group comprising silyl, sulfonic acid, sulfonyl, formyl, amine, imine, nitrile, mercapto, nitro, halogen, C 1-12 Alkyl, C 6-12 Aryl, C 1-12 Alkoxy, hydroxy or a combination of these groups.

[0077] Preferred substituents are, for example, groups promoting solubility, such as alkyl or alkoxy groups, and electron withdrawing groups, such as fluoro, nitro or nitrile.

[0078] Preferred substituents (also referred to as "L" above and below), unless otherwise specified, are F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R z )2, -C(=O)Y 1 、C(=O)R z 、-N(R z )2, where R z has the meaning indicated above, and Y 1 represents halogen, optionally substituted silyl or aryl having 6 to 40, preferably 6 to 20 C atoms, and straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, preferably 2 to 12 C atoms, where one or more H atoms may optionally be replaced by F or Cl.

[0079] "Substituted silyl or aryl" preferably refers to substituted silyl or aryl groups. y1 、-OR y1 、-CO-R y1 、-CO-OR y1 、-O-CO-R y1 OR-O-CO-OR y1 Substitution, where R y1 has the meaning indicated above.

[0080] Particularly preferred substituents L are, for example, F, Cl, CN, CH3, C2H5, -CH(CH3)2, OCH3, OC2H5, CF3, OCF3, OCHF2, OC2F5, and phenyl.

[0081] In this context, "halogen" means F, Cl, Br or I.

[0082] In this context, the terms "alkyl", "aryl", "heteroaryl" and the like also include polyvalent groups such as alkylene, arylene, heteroarylene and the like.

[0083] The term "director" is known in the art and refers to the preferred orientation direction of the long molecular axis (in the case of rod-shaped compounds) or the short molecular axis (in the case of discotic compounds) of the liquid crystal molecules. In the case of uniaxial ordering of such anisotropic molecules, the director is the axis of anisotropy.

[0084] The term "alignment" or "orientation" relates to the alignment (sequence of orientation) of anisotropic units of a material (e.g. small molecules or fragments of macromolecules) in a common direction called the "alignment direction". In an alignment layer of a liquid crystal material, the liquid crystal director is aligned with the alignment direction, so that the alignment direction corresponds to the direction of the anisotropic axis of the material.

[0085] The term "planar alignment", e.g. in a layer of liquid crystal material, means that part of the liquid crystal molecules have their long molecular axes (in the case of rod-shaped compounds) or short molecular axes (in the case of discotic compounds) aligned substantially parallel (about 180°) to the plane of the layer.

[0086] The term "homeotropic alignment", for example in a layer of liquid crystal material, means that the long molecular axes (in the case of rod-like compounds) or short molecular axes (in the case of discotic compounds) of some of the liquid crystal molecules are oriented at an angle θ ("tilt angle") of about 80° to 90° relative to the plane of the layer.

[0087] The term "homogeneous orientation" or "homogeneous alignment" of a liquid crystal material, for example in a layer of the material, means that the long molecular axes (in the case of rod-shaped compounds) or the short molecular axes (in the case of discotic compounds) of the liquid crystal molecules are oriented in substantially the same direction. In other words, the lines of the liquid crystal directors are parallel.

[0088] Unless otherwise expressly stated, the wavelength of light in this application is generally referred to as 550 nm.

[0089] The birefringence Δn is defined herein by the following equation.

[0090] Δn=n e -n o

[0091] where ne is the extraordinary refractive index, n o is the ordinary refractive index, and the effective mean refractive index n av . is given by the following formula:

[0092] n av .=[(2n o 2 +n e 2 ) / 3] 1 / 2

[0093] Extraordinary refractive index n e and the ordinary refractive index n o It can be measured using an Abbe refractometer.

[0094] In this application, the term "dielectrically positive" is used for compounds or components with Δε>3.0, "dielectrically neutral" is used for compounds or components with -1.5≤Δε≤3.0, and "dielectrically negative" is used for compounds or components with Δε<-1.5. Δε is measured at a frequency of 1 kHz and at 20°C. The dielectric anisotropy of each compound is determined by the results of a 10% solution of the corresponding individual compound in a nematic host mixture. In the case where the solubility of each compound in the host medium is less than 10%, its concentration is reduced by a factor of 2 until the resulting medium is stable enough, at least enough to determine its properties. However, preferably, the concentration is kept at at least 5% to keep the significance of the results as high as possible. The capacitance of the test mixture is determined in cells with homeotropic and planar alignment. The cell gap of both types of cells is about 20 μm. The applied voltage is a rectangular wave with a frequency of 1 kHz and a root mean square value of typically 0.5 V to 1.0 V; however, it is always selected to be lower than the capacitance threshold of the respective test mixture.

[0095] △ε is defined as (ε || -ε ⊥ ), and ε av. is (ε || +2ε ⊥ ) / 3. The dielectric constant of the compound is determined by the change in the respective value of the host medium after adding the target compound. These values ​​are extrapolated to a concentration of 100% of the target compound. Typical host media are ZLI-4792 or ZLI-2857, both commercially available from Merck, Darmstadt.

[0096] For the present invention,

[0097]

[0098] represents trans-1,4-cyclohexylene,

[0099]

[0100] It represents 1,4-phenylene.

[0101] For the present invention, the group -CO-O-, -COO--C(=O)O- or -CO2- is represented by The ester group, and the group -O-CO--OCO-, -OC(=O)-, -O2C- or -OOC- are expressed as Ester group.

[0102] Furthermore, the definitions as given in C. Tschierske, G. Pelzl and S. Diele, Angew. Chem. 2004, 116, 6340-6368 shall apply to non-defined terms related to liquid crystal materials in the present application.

[0103] Details

[0104] In detail, the present invention relates to compounds or photoreactive mesogens of formula I,

[0105]

[0106] in

[0107] A 11 represents a group selected from the following groups:

[0108] a) the group consisting of 1,4-phenylene and 1,3-phenylene, in addition, one or two CH groups may be replaced by N and in addition, one or more H atoms may be replaced by L,

[0109] b) a group selected from the group consisting of,

[0110]

[0111] wherein, in addition, one or more H atoms in these radicals may be replaced by L, and / or one or more double bonds may be replaced by single bonds, and / or one or more CH groups may be replaced by N, and A each independently of one another has for each occurrence 11 One of the meanings, or

[0112] a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, and wherein, in addition, one or more H atoms may be replaced by F, or

[0113] b) tetrahydropyran-2,5-diyl, 1,3-di the group consisting of alkane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or poly-substituted by L,

[0114] L, in each occurrence, identically or differently, represents -OH, -F, -Cl, -Br, -I, -CN, -NO2, SF5, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R z )2, -C(=O)R z 、-N(R z )2, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or linear or branched or cyclic alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, preferably 1 to 12 C atoms, more preferably 1 to 6 C atoms, wherein, in addition, one or more H atoms may be replaced by F or Cl, or X 21 -Sp 21 -R 21 ,

[0115] M represents -O-, -S-, -CH2-, -CHR z -or-CR y R z -,and

[0116] R y and R z each independently of one another represents H, CN, F or alkyl having 1 to 12 C atoms, wherein one or more H atoms may be replaced by F, preferably H, methyl, ethyl, propyl, butyl, more preferably H or methyl, in particular H,

[0117] Y 11 and Y 12 each independently of one another represents H, F, phenyl or optionally fluorinated alkyl having 1 to 12 C atoms, preferably H, methyl, ethyl, propyl, butyl, more preferably H or methyl, in particular H,

[0118] Z, independently of one another, represents at each occurrence a single bond, -COO-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -OCF2-, -CF2O-, -(CH2) n -, -CF2CF2-, -CH=CH-, -CF=CF-, -CH=CH-COO-, -OCO-CH=CH-, -CO-S-, -S-CO-, -CS-S-, -S-CS-, -S-CSS- or -C≡C-, preferably a single bond, -COO-, -OCO-, -OCF2-, -CF2O- or -(CH2)n -, more preferably a single bond, -COO- or -OCO-,

[0119] n represents an integer of 2-8, preferably 2,

[0120] o and p each and independently represent 0, 1 or 2, preferably 1,

[0121] X 11 and X 21 represents, independently of one another at each occurrence, a single bond, -CO-O-, -O-CO-, -O-COO-, -O-, -CH=CH-, -C≡C-, -CF2-O-, -O-CF2-, -CF2-CF2-, -CH2-O-, -O-CH2-, -CO-S-, -S-CO-, -CS-S-, -S-CS-, -S-CSS- or -S-, preferably a single bond -CO-O-, -O-CO-, -O-COO- or -O-, more preferably a single bond or -O-,

[0122] Sp 11 and Sp 21 Each and independently at each occurrence represents a single bond or a spacer group containing 1 to 20 C atoms, wherein one or more non-adjacent and non-terminal CH2 groups may also be replaced by -O-, -S-, -NH-, -N(CH3)-, -CO-, -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O-, -CF2-, -CF2O-, -OCF2-, -C(OH)-, -CH(alkyl)-, -CH(alkenyl)-, -CH(alkoxy)-, -CH(oxaalkyl)-, -CH =CH- or -C≡C-, but in such a way that no two O-atoms are adjacent to one another and no two radicals selected from the group consisting of -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O- and -CH=CH- are adjacent to one another, preferably alkylene with 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, more preferably straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene,

[0123] R 11 represents P,

[0124] R 21 represents P, halogen, CN, optionally fluorinated alkyl or alkenyl having up to 15 C atoms, wherein one or more non-adjacent CH2-groups may be replaced by -O-, -S-, -CO-, -C(O)O-, -OC(O)-, OC(O)-O-, preferably P,

[0125] P is each and independently of one another at each occurrence a polymerizable group,

[0126] q and r each and independently represent an integer of 0-8, preferably q+r≥1 and ≤16, more preferably q and r each and independently represent an integer of 1-8,

[0127] In the present application, a polymerizable group (P) is a group suitable for polymerization (such as free radical or ionic chain polymerization, addition polymerization or condensation polymerization) or a polymer-like reaction (such as addition or condensation on the main polymer chain). Particularly preferred are groups for chain polymerization, especially groups containing a C=C double bond or a -C≡C- triple bond, and groups suitable for ring-opening polymerization, such as an oxetane group or an epoxy group.

[0128] Preferred groups P are selected from CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -(O) k3 -、CW 1 =CH-CO-(O) k3 -、CW 1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -、HS-CW 2 W 3 -、HW 2 N-、HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -、CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 Each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 Each independently represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene which is optionally substituted by one or more groups L as defined above, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0129] Further preferably, P represents a group

[0130]

[0131] Preferred groups

[0132]

[0133] Y represents H, F, phenyl or optionally fluorinated alkyl having 1 to 12 C atoms, preferably H, methyl, ethyl, propyl, butyl, more preferably H or methyl, in particular H.

[0134] Particularly preferred groups P are selected from CH2=CW 1 -CO-O-, in particular CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, as well as CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-, or group

[0135]

[0136] Y represents H or methyl, especially H.

[0137] Very particularly preferred radicals P are selected from acrylate, methacrylate, fluoroacrylate, and vinyloxy, chloroacrylate, oxetane, epoxy and

[0138]

[0139] Y represents H or methyl, in particular H, and among these preferably acrylate or methacrylate groups or groups,

[0140]

[0141] wherein Y represents H or methyl.

[0142] The compound of formula I is preferably selected from the compounds of sub-formulae I-1 to I-9,

[0143]

[0144]

[0145] Where R 11 , R 21 , A 11 , X 11 , X 21 , Y 11 , Y 12 、Sp 11 and Sp 21 has one of the meanings given above in formula I, A 12 To A 23 has one of the meanings for A in Formula I, A 11 has one of the meanings given above under formula I, and Z 11 To Z 22 has one of the meanings given above under formula I for Z,

[0146] Further preferred compounds of formula I-1 are selected from the compounds of formulae I-1-1 to I-1-3,

[0147]

[0148]

[0149] Where R 11 , R 21 , A 11 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given in formula I above, A 21 has one of the meanings for A in formula I, preferably A 21 represents the group consisting of 1,4-phenylene, wherein, in addition, one or two CH groups may be replaced by N, wherein, in addition, one or two H atoms may be replaced by L as given above under formula I, or the group consisting of trans-1,4-cyclohexylene, 1,4-cycloalkenylene, wherein, in addition, one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, and wherein, in addition, one or more H atoms may be replaced by F,

[0150] Preferred compounds of formula I-2 are selected from the following subformulae I-2-1 to I-2-3:

[0151]

[0152] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, and Z 11 has one of the meanings given above for Z under formula I, A 12 , A 21 has one of the meanings given above for A in formula I, preferably A 12 , A 21 each and independently represents the group consisting of 1,4-phenylene, wherein, in addition, one or two CH groups may be replaced by N, and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or the group consisting of trans-1,4-cyclohexylene, 1,4-cycloalkenylene, wherein, in addition, one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, and wherein, in addition, one or more H atoms may be replaced by F,

[0153] Preferred compounds of formula I-3 are selected from the following sub-formulae I-3-1 to I-3-3,

[0154]

[0155] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, Z 21 has one of the meanings given above for Z under formula I, A 21 and A 22 has one of the meanings given above for A in formula I. Preferably A 21 and A 22 each and independently represents the group consisting of 1,4-phenylene, wherein, in addition, one or two CH groups may be replaced by N, and wherein, in addition, one or more H atoms may be replaced by L as given above under formula I, or the group consisting of trans-1,4-cyclohexylene, 1,4-cycloalkenylene, wherein, in addition, one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, and wherein, in addition, one or more H atoms may be replaced by F,

[0156] Preferred compounds of formula I-4 are selected from the following sub-formulae,

[0157]

[0158] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, A 12 , A 21 and A 22 has one of the meanings given above for A under formula I, Z 11 and Z 21 has one of the meanings given above under formula I for Z, r and q represent 1, 2 or 3, s represents an integer from 1 to 6, and A 12 , A 21 and A 22 has one of the meanings given above for A under formula I. Preferably, A 12 , A 21 and A 22 Each and independently represents the group consisting of 1,4-phenylene, in which one or two CH groups can be replaced by N, and in which, in addition, one or more H atoms can be replaced by L as given above under formula I, or the group consisting of trans-1,4-cyclohexylene, 1,4-cycloalkenylene, in which, in addition, one or more non-adjacent CH2 groups can be replaced by -O- and / or -S-, and in which, in addition, one or more H atoms can be replaced by F.

[0159] Preferred compounds of formula I-5 are selected from the following sub-formulae,

[0160]

[0161] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, Z 11 , Z 12 and Z 21 has one of the meanings given above for Z under formula I, and A 12 , A 13 , A 21 and A 22 has one of the meanings given above for A under formula I. Preferably, A 12 , A 13 , A 21 and A 22each and independently represents the group consisting of 1,4-phenylene, wherein one or two CH groups may be replaced by N, and wherein additionally one or more H atoms may be replaced by L as given above under formula I, or the group consisting of trans-1,4-cyclohexylene, 1,4-cycloalkenylene, wherein, additionally, one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, and wherein, additionally, one or more H atoms may be replaced by F.

[0162] Preferred compounds of formula I-2-1 are compounds of the following sub-formula,

[0163]

[0164]

[0165] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, Z 11 has one of the meanings given above under formula I for Z, and

[0166] Group Each and independently or

[0167] express as well as

[0168] wherein L has one of the meanings given above in formula I and preferably represents F, Cl, OCH3, COCH3 or alkyl having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0169] Preferred compounds of formulae I-3-1 to I-3-3 are compounds of the following sub-formulae:

[0170]

[0171]

[0172] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21has one of the meanings given above in formula I, Z 21 has one of the meanings given above under formula I for Z, and

[0173] Group Each and independently or

[0174] express as well as

[0175] wherein L has one of the meanings given above in formula I and is preferably F, Cl, OCH3, COCH3 or alkyl having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0176] Preferred compounds of formula I-4-1 are compounds of the following sub-formula:

[0177]

[0178] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, Z 11 and Z 21 has one of the meanings given above under formula I for Z, r and q represent 1, 2 or 3 and s represents an integer from 1 to 6, and

[0179] Group Each and independently

[0180] express as well as

[0181] wherein L has one of the meanings given above in formula I and is preferably F, Cl, OCH3, COCH3 or alkyl having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0182] Preferred compounds of formula I-5-1 are compounds of the following sub-formula:

[0183]

[0184] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, Z 11 , Z 12 and Z 21 each and independently has one of the meanings given above under formula I for Z, r and q represent 1, 2 or 3 and s represents an integer from 1 to 6, and

[0185] Group Each and independently

[0186] express as well as

[0187] wherein L has one of the meanings given above in formula I and is preferably F, Cl, OCH3, COCH3 or alkyl having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0188] Further preferred compounds of formula I-2-1a are compounds of the following sub-formula:

[0189]

[0190] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, and L represents F, Cl, OCH3, COCH3 or an alkyl radical having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0191] Further preferred compounds of formulae I-3-1a to I-3-1c are compounds of the following sub-formulae:

[0192]

[0193]

[0194] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, and L represents F, Cl, OCH3, COCH3 or an alkyl radical having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0195] Further preferred compounds of formula I-4-1 are compounds of the following sub-formula:

[0196]

[0197]

[0198] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, and L represents F, Cl, OCH3, COCH3 or an alkyl radical having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21 -R 21 .

[0199] Further preferred compounds of formula I-5-1 are compounds of the following sub-formula:

[0200]

[0201]

[0202] Where R 11 , R 21 , X 11 , X 21 、Sp 11 and Sp 21 has one of the meanings given above in formula I, and L represents F, Cl, OCH3, COCH3 or an alkyl radical having 1 to 6 C atoms, for example methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or X 21 -Sp 21-R 21 .

[0203] Further preferred compounds of formula I-2-1a are compounds of the following sub-formula:

[0204]

[0205]

[0206]

[0207] in

[0208] X each and independently represents methyl or H, preferably methyl,

[0209] Y represents a methyl group or H,

[0210] Sp 11 and Sp 21 has one of the meanings given above in formula I and preferably each and independently represents an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN,

[0211] More preferably, linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and

[0212] L represents F, Cl, OCH3 and COCH3 or an alkylene group having 1 to 6 C atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0213] Further preferred compounds of formulae I-3-1a to I-3-1c are compounds of the following sub-formulae:

[0214]

[0215]

[0216]

[0217]

[0218]

[0219]

[0220] in

[0221] X each and independently represents methyl or H, preferably methyl,

[0222] Y represents a methyl group or H,

[0223] Sp 11 and Sp 21 has one of the meanings given above in formula I, and preferably each and independently represents an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, more preferably a linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and

[0224] L represents F, Cl, OCH3 and COCH3 or an alkylene group having 1 to 6 C atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0225] Further preferred compounds of formula I-4-1 are compounds of the following sub-formula:

[0226]

[0227]

[0228]

[0229]

[0230]

[0231] in

[0232] X each and independently represents methyl or H, preferably methyl,

[0233] Y represents a methyl group or H,

[0234] Sp 11 and Sp 21 has one of the meanings given above in formula I and preferably each and independently represents an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN,

[0235] More preferably, linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and

[0236] L represents F, Cl, OCH3 and COCH3 or an alkylene group having 1 to 6 C atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0237] Further preferred compounds of formula I-5-1 are compounds of the following sub-formula:

[0238]

[0239]

[0240]

[0241]

[0242]

[0243] in

[0244] X each and independently represents methyl or H, preferably methyl,

[0245] Y represents a methyl group or H,

[0246] Sp 11 and Sp 21 has one of the meanings given above in formula I and preferably each and independently represents an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN,

[0247] More preferably, linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, and

[0248] L represents F, Cl, OCH3 and COCH3 or an alkylene group having 1 to 6 C atoms, preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0249] The compounds of formula I and its subformulae are preferably synthesized according to or analogously to the procedures described in WO 2017 / 102068 and JP 2006-6232809.

[0250] The medium according to the invention preferably comprises 0.01 to 10%, particularly preferably 0.05 to 5% and most preferably 0.1 to 3% of component A) comprising the compound of formula I according to the invention.

[0251] The medium preferably comprises one, two or three, more preferably one or two and most preferably one compound of formula I according to the invention.

[0252] In a preferred embodiment, component A) consists of compounds of the formula I.

[0253] In a preferred embodiment, the LC host mixture (component B) according to the present invention comprises one or more, preferably two or more, low molecular weight (i.e. monomeric or non-polymerized) compounds which are stable or non-reactive with respect to polymerization or photoalignment under the conditions used for polymerization of the polymerizable compound or photoalignment of the photoreactive mesogen of formula I.

[0254] In principle, suitable host mixtures are any dielectrically negative or positive LC mixtures which are suitable for use in conventional VA, IPS or FFS displays.

[0255] Suitable LC mixtures are known to the person skilled in the art and are described in the literature.LC media with negative dielectric anisotropy for VA displays are described, for example, in EP 1 378 557 A1.

[0256] Suitable LC mixtures with positive dielectric anisotropy for LCDs and in particular for IPS displays are known, for example, from JP 07-181 439 (A), EP 0 667 555, EP 0 673 986, DE 195 09 410, DE 195 28 106, DE 19528 107, WO 96 / 23 851, WO 96 / 28 521 and WO 2012 / 079676.

[0257] Preferred embodiments of the liquid-crystalline media according to the invention having negative or positive dielectric anisotropy are indicated below and are explained in more detail with the aid of examples.

[0258] The LC host mixture is preferably a nematic LC mixture and preferably has no chiral LC phase.

[0259] In a preferred embodiment of the present invention, the LC medium contains an LC host mixture with negative dielectric anisotropy. Preferred embodiments of such LC media and corresponding LC host mixtures are those of the following sections a) to z):

[0260] a) LC medium comprising one or more compounds of formula CY and / or formula PY:

[0261]

[0262] in

[0263] a means 1 or 2,

[0264] b represents 0 or 1,

[0265] express

[0266] R 1 and R2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0267] Z x and Z y Each independently represents -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, L 1-4 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0268] Preferably, L 1 With L 2 Both mean F, or L 1 With L 2 One of them represents F and the other represents Cl, or L 3 With L 4 Both mean F or L 3 With L 4 One of represents F and the other represents Cl.

[0269] The compound of formula CY is preferably selected from the group consisting of the following sub-formulae:

[0270]

[0271]

[0272]

[0273]

[0274]

[0275] Where a represents 1 or 2, alkyl and alkyl * Each independently of one another represents a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0276] The compound of formula PY is preferably selected from the group consisting of the following sub-formulae:

[0277]

[0278]

[0279]

[0280] Among them, alkyl and alkyl * Each independently of one another represents a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0281] b) LC media which additionally comprise one or more compounds of the formula:

[0282]

[0283] The various groups have the following meanings:

[0284] express

[0285]

[0286] express

[0287] R 3 and R 4 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another,

[0288] Z y It represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, and preferably represents a single bond.

[0289] The compound of formula ZK is preferably selected from the group consisting of the following subformulae:

[0290]

[0291]

[0292] Among them, alkyl and alkyl * Each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical having 2 to 6 C atoms. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0293] Particularly preferred are compounds of formulae ZK1 and ZK3.

[0294] Particularly preferred compounds of formula ZK are selected from the following sub-formulae:

[0295]

[0296]

[0297] Among them, propyl, butyl and pentyl are straight chain groups.

[0298] Most preferred are compounds of formula ZK1a and ZK3a.

[0299] c) LC media which additionally comprise one or more compounds of the formula:

[0300]

[0301] where the individual radicals have the following meanings on each occurrence, identically or differently:

[0302] R 5 and R 6 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0303] express

[0304] express and

[0305] e represents 1 or 2.

[0306] The compound of formula DK is preferably selected from the group consisting of the following subformulae:

[0307]

[0308]

[0309] Among them, alkyl and alkyl * Each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical having 2 to 6 C atoms. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0310] d) LC media which additionally comprise one or more compounds of the formula:

[0311]

[0312] The various groups have the following meanings:

[0313] express

[0314] wherein at least one ring F is different from cyclohexylene,

[0315] f means 1 or 2,

[0316] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another,

[0317] Z x represents -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,

[0318] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0319] Preferably, the group L 1 With L 2 Both represent F, or a group L 1 With L 2 One of represents F and the other represents Cl.

[0320] The compound of formula LY is preferably selected from the group consisting of the following sub-formulae:

[0321]

[0322]

[0323]

[0324]

[0325] Where R 1 has the meaning indicated above, alkyl represents a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, and v represents an integer from 1 to 6. 1 Preferably, it represents a straight-chain alkyl radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, in particular CH3, C2H5, n-C3H7, n-C4H9, n-C5H 11 , 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-.

[0326] e) LC medium which additionally comprises one or more compounds selected from the group consisting of:

[0327]

[0328]

[0329] Where alkyl represents C 1-6 -alkyl, L x represents H or F, and X represents F, Cl, OCF3, OCHF2 or OCH=CF2. Particularly preferred are compounds of formula G1, wherein X represents F.

[0330] f) LC medium which additionally comprises one or more compounds selected from the group consisting of:

[0331]

[0332]

[0333]

[0334] Where R 5 With the above for R 1 One of the meanings indicated, alkyl means C 1-6 -alkyl, d represents 0 or 1, and z and m each independently represent an integer of 1 to 6. 5 C is particularly preferred 1-6 -alkyl or C 1-6 -alkoxy or C 2-6 -alkenyl, d is preferably 1. The LC media according to the invention preferably comprise one or more compounds of the abovementioned formulae in an amount of ≥ 5% by weight.

[0335] g) LC medium which additionally comprises one or more biphenyl compounds selected from the group consisting of:

[0336]

[0337] Among them, alkyl and alkyl * each independently represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and akenyl * each independently of one another represents a straight-chain alkenyl radical having 2 to 6 C atoms. * Preferably it represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0338] The proportion of biphenyls of the formulae B1 to B3 in the LC mixture is preferably at least 3% by weight, in particular ≥5% by weight.

[0339] Compounds of formula B2 are particularly preferred.

[0340] The compounds of the formulae B1 to B3 are preferably selected from the group consisting of the following subformulae:

[0341]

[0342] Among them, alkyl * denotes an alkyl radical having 1 to 6 C atoms. The medium according to the invention particularly preferably comprises one or more compounds of the formula B1a and / or B2e.

[0343] h) LC medium which additionally comprises one or more terphenyl compounds of the formula:

[0344]

[0345] Where R 5 and R 6 each independently of the others has one of the meanings indicated above, and

[0346]

[0347] Each independently expresses

[0348]

[0349] Where L 5 represents F or Cl, preferably F, and L 6 represents F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F.

[0350] The compound of formula T is preferably selected from the group consisting of the following sub-formulae:

[0351]

[0352]

[0353]

[0354] wherein R represents a straight-chain alkyl or alkoxy group having 1 to 7 C atoms, R * R represents a straight-chain alkenyl group having 2 to 7 C atoms, (O) represents an oxygen atom or a single bond, and m represents an integer of 1 to 6. * Preferably it represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0355] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.

[0356] The LC media according to the invention preferably comprise from 0.5 to 30% by weight, in particular from 1 to 20% by weight, of terphenyl of the formula T and preferred subformulae thereof.

[0357] Particular preference is given to compounds of the formulae T1, T2, T3 and T21. In these compounds, R preferably represents alkyl and alkoxy, each having 1 to 5 C atoms.

[0358] Terphenyl is preferably used in the mixture according to the invention if a Δn value of ≥ 0.1 is to be achieved in the mixture. Preferred mixtures comprise 2 to 20% by weight of one or more terphenyl compounds of the formula T, which are preferably selected from the group of compounds T1 to T22.

[0359] i) LC medium which additionally comprises one or more compounds selected from the group consisting of:

[0360]

[0361] Where R 1 and R 2 has the meanings indicated above and preferably each independently of one another denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

[0362] Preferred media comprise one or more compounds selected from the group consisting of formulae O1, O3 and O4.

[0363] k) LC medium which additionally comprises one or more compounds of the formula:

[0364]

[0365] in

[0366] express

[0367]

[0368] R 9 represents H, CH3, C2H5 or n-C3H7, (F) represents an optional fluorine substituent, and q represents 1, 2 or 3, and R 7 With R 1 In one of the indicated meanings, the amount is preferably >3% by weight, in particular ≥5% by weight and very particularly preferably 5 to 30% by weight.

[0369] Particularly preferred compounds of formula FI are selected from the group consisting of the following subformulae:

[0370]

[0371]

[0372] Where R 7 Preferably represents a straight chain alkyl group, and R 9 represents CH3, C2H5 or n-C3H7. Particularly preferred are compounds of formula FI1, FI2 and FI3.

[0373] 1) LC medium which additionally comprises one or more compounds selected from the group consisting of:

[0374]

[0375] Where R 8 With R 1 The alkyl radicals have the meanings indicated, and alkyl denotes a straight-chain alkyl radical having 1 to 6 C atoms.

[0376] m) LC media which additionally comprise one or more compounds containing tetrahydronaphthyl or naphthyl units, for example compounds selected from the group consisting of:

[0377]

[0378]

[0379]

[0380] in

[0381] R 10 and R 11 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0382] And R 10 and R 11 preferably represents a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, and

[0383] Z 1 and Z 2 Each independently represents -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CH-CH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CH2- or a single bond.

[0384] n) LC medium which additionally comprises one or more difluorodibenzochromans and / or chromans of the following formulae:

[0385]

[0386] in

[0387] R 11 and R 12Each independently has the above R 11 One of the meanings indicated.

[0388] Ring M is trans-1,4-cyclohexylene or 1,4-phenylene,

[0389] Z m represents -C2H4-, -CH2O-, -OCH2-, -CO-O- or -O-CO-,

[0390] c is 0, 1, or 2,

[0391] Preferably the amount is 3 to 20% by weight, in particular the amount is 3 to 15% by weight.

[0392] Particularly preferred compounds of formula BC, CR and RC are selected from the group consisting of the following subformulae:

[0393]

[0394]

[0395]

[0396] Among them, alkyl and alkyl * each independently represents a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, c is 1 or 2, and alkenyl and akenyl * each independently of one another represents a straight-chain alkenyl radical having 2 to 6 C atoms. * Preferably it represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0397] Very particular preference is given to mixtures comprising one, two or three compounds of the formula BC-2.

[0398] o) LC medium which additionally comprises one or more fluorinated phenanthrenes and / or dibenzofurans of the following formulae:

[0399]

[0400] Where R 11 and R 12 Each independently has the above R 11 One of the indicated meanings, b represents 0 or 1, L represents F, and r represents 1, 2 or 3.

[0401] Particularly preferred compounds of formula PH and BF are selected from the group consisting of the following subformulae:

[0402]

[0403]

[0404] wherein R and R′ each independently represent a straight-chain alkyl or alkoxy group having 1 to 7 C atoms.

[0405] p) LC medium which additionally comprises one or more monocyclic compounds of the formula

[0406]

[0407] in

[0408] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0409] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0410] Preferably, L 1 With L 2 Both mean F, or L 1 With L 2 One of them represents F and the other represents Cl,

[0411] The compound of formula Y is preferably selected from the group consisting of the following sub-formulae:

[0412]

[0413]

[0414] Among them, Alkyl and Alkyl * Each independently represents a straight-chain alkyl radical having 1 to 6 C atoms, Alkoxy represents a straight-chain alkoxy radical having 1 to 6 C atoms, Alkenyl and Akenyl * Each independently of one another represents a straight-chain alkenyl group having 2 to 6 C atoms, and O represents an oxygen atom or a single bond. *Preferably it represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0415] Particularly preferred compounds of formula Y are selected from the group consisting of the following subformulae:

[0416]

[0417] Alkoxy here preferably denotes straight-chain alkoxy having 3, 4 or 5 C atoms.

[0418] q) LC media which, apart from the stabilizers according to the invention, in particular stabilizers of the formula I or a subformulae thereof, and comonomers, do not comprise compounds containing terminal vinyloxy groups (—O—CH═CH 2 ).

[0419] r) LC medium comprising 1 to 5, preferably 1, 2 or 3, stabilizers, preferably selected from the stabilizers according to the invention, in particular stabilizers of the formula I or a subformulae thereof.

[0420] s) LC media in which the proportion of stabilizer, in particular stabilizer of the formula I or a subformulae thereof, in the overall mixture is from 1 to 1500 ppm, preferably from 100 to 1000 ppm.

[0421] t) LC medium comprising 1 to 8, preferably 1 to 5, compounds of the formula CY1, CY2, PY1 and / or PY2. The proportion of these compounds in the overall mixture is preferably 5% to 60%, particularly preferably 10% to 35%. The content of these individual compounds is preferably 2% to 20% in each case.

[0422] u) LC medium comprising 1 to 8, preferably 1 to 5, compounds of the formula CY9, CY10, PY9 and / or PY10. The proportion of these compounds in the overall mixture is preferably 5% to 60%, particularly preferably 10% to 35%. The content of these individual compounds is preferably in each case 2% to 20%.

[0423] v) LC medium comprising 1 to 10, preferably 1 to 8, compounds of the formula ZK, in particular compounds of the formula ZK1, ZK2 and / or ZK6. The proportion of these compounds in the overall mixture is preferably 3% to 25%, particularly preferably 5% to 45%. The content of these individual compounds is preferably in each case 2% to 20%.

[0424] w) LC media in which the proportion of compounds of the formulae CY, PY and ZK in the overall mixture is greater than 70%, preferably greater than 80%.

[0425] x) LC media, wherein the LC host mixture contains one or more alkenyl-containing compounds, preferably selected from the group consisting of: formula CY, PY and LY, wherein R 1 and R 2 One or both of represents a straight chain alkenyl group having 2 to 6 C atoms; Formula ZK and DK, wherein R 3 and R 4 One or both or R 5 and R 6 One or both of represents a straight-chain alkenyl group having 2 to 6 C atoms; and formulae B2 and B3; very preferably selected from formulae CY15, CY16, CY24, CY32, PY15, PY16, ZK3, ZK4, DK3, DK6, B2 and B3, most preferably selected from formulae ZK3, ZK4, B2 and B3. The concentration of these compounds in the LC host mixture is preferably 2 to 70%, very preferably 3 to 55%.

[0426] y) LC medium containing one or more, preferably 1 to 5, compounds selected from the group consisting of the formulae PY1 to PY8, very preferably the formula PY2. The proportion of these compounds in the overall mixture is preferably 1% to 30%, particularly preferably 2% to 20%. The content of these individual compounds is preferably in each case 1% to 20%.

[0427] z) LC media containing one or more, preferably 1, 2 or 3, compounds of the formula T2. The content of these compounds in the overall mixture is preferably from 1 to 20%.

[0428] In another preferred embodiment of the present invention, the LC medium contains an LC host mixture with positive dielectric anisotropy. Preferred embodiments of such LC media and corresponding LC host mixtures are those of the following parts aa) to mmm):

[0429] aa) LC medium, characterized in that it comprises one or more compounds selected from the group of compounds of formula II and formula III

[0430]

[0431] in

[0432] R 20each identically or differently represents a halogenated or unsubstituted alkyl or alkoxy group having 1 to 15 C atoms, wherein one or more CH2 groups in these groups may each independently of one another be substituted by -C≡C-, -CF2O-, -CH=CH-, -C≡C-, -C≡O-, -C≡ ...C-, -C≡O-, -C≡CH-, -C≡C-, -C≡C-, -C≡O-, -C≡CH-, -C≡C-, -C -O-, -CO-O- or -O-CO-,

[0433] X 20 each identically or differently represents F, Cl, CN, SF5, SCN, NCS, halogenated alkyl, halogenated alkenyl, halogenated alkoxy or halogenated alkenyloxy, each having up to 6 C atoms, and

[0434] Y 20-24 each identically or differently represents H or F;

[0435] W represents H or methyl,

[0436] Each independently expresses

[0437] The compound of formula II is preferably selected from the following formulae:

[0438]

[0439] Where R 20 and X 20 has the meaning indicated above.

[0440] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably X represents F. Particular preference is given to compounds of the formulae IIa and IIb, especially compounds of the formulae IIa and IIb in which X represents F.

[0441] The compound of formula III is preferably selected from the following formulae:

[0442]

[0443] Where R 20 and X 20 has the meaning indicated above.

[0444] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F. Particularly preferred are compounds of formula IIIa and IIIe, especially compounds of formula IIIa;

[0445] bb) LC medium which additionally comprises one or more compounds selected from the following formulae:

[0446]

[0447] in

[0448] R 20 , X 20 , W and Y 20-23 has the meaning indicated in Formula II above, and

[0449] Z 20 represents -C2H4-, -(CH2)4-, -CH=CH-, -CF=CF-, -C2F4-, -CH2CF2-, -CF2CH2-, -CH2O-, -OCH2-, -COO- or -OCF2-, and also represents a single bond in Formula V and Formula VI, and also represents -CF2O- in Formula V and Formula VIII,

[0450] r represents 0 or 1, and

[0451] s represents 0 or 1;

[0452] - The compound of formula IV is preferably selected from the following formulae:

[0453]

[0454] Where R 20 and X 20 has the meaning indicated above.

[0455] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F or OCF3, and OCF=CF2 or Cl;

[0456] - The compound of formula V is preferably selected from the following formulae:

[0457]

[0458]

[0459] Where R 20 and X 20 has the meaning indicated above.

[0460] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F and OCF3, as well as OCHF2, CF3, OCF=CF2 and OCH=CF2;

[0461] - The compound of formula VI is preferably selected from the following formulae:

[0462]

[0463]

[0464] Where R 20 and X 20 has the meaning indicated above.

[0465] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F, as well as OCF3, CF3, CF=CF2, OCHF2 and OCH=CF2;

[0466] - The compound of formula VII is preferably selected from the following formulae:

[0467]

[0468] Where R 20 and X 20 has the meaning indicated above.

[0469] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably it represents F, as well as OCF3, OCHF2 and OCH=CF2.

[0470] cc) The medium further comprises one or more compounds selected from the formulae ZK1 to ZK10 given above. Particularly preferred are compounds of the formulae ZK1 and ZK3. Particularly preferred compounds of the formula ZK are selected from the subformulae ZK1a, ZK1b, ZK1c, ZK3a, ZK3b, ZK3c and ZK3d.

[0471] dd) The medium additionally comprises one or more compounds selected from the group consisting of the formulae DK1 to DK12 given above. A particularly preferred compound is DK3.

[0472] ee) the medium further comprises one or more compounds selected from the following formulae:

[0473]

[0474] Where X 20 has the meaning indicated above, and

[0475] L means H or F,

[0476] "alkenyl" means C 2-6 -alkenyl.

[0477] ff) The compounds of formula DK-3a and IX are preferably selected from the following formulae:

[0478]

[0479] Among them, "alkyl" means C 1-6 -alkyl, preferably n-C3H7, n-C4H9 or n-C5H 11 , especially n-C3H7.

[0480] gg) The medium further comprises one or more compounds selected from the formulae B1, B2 and B3 given above, preferably from the formula B2. The compounds of the formulae B1 to B3 are particularly preferably selected from the formulae B1a, B2a, B2b and B2c.

[0481] hh) the medium further comprises one or more compounds selected from the following formulae:

[0482]

[0483] Where L 20 indicates H or F, and R 21 and R 22 each identically or differently represents n-alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms, and preferably each identically or differently represents alkyl having 1 to 6 C atoms.

[0484] ii) the medium comprises one or more compounds of the following formulae:

[0485]

[0486] Among them, W, R 20 , X 20 and Y 20-23 has the meaning indicated in formula III, and

[0487] Each independently expresses

[0488]

[0489] and

[0490] express

[0491] The compounds of formula XI and XII are preferably selected from the following formulae:

[0492]

[0493]

[0494] Where R 20 and X 20 has the meaning indicated above, and preferably R 20 represents an alkyl group having 1 to 6 C atoms, and X20 Indicates F.

[0495] The mixtures according to the invention particularly preferably comprise at least one compound of the formula XIIa and / or XIIe.

[0496] jj) The medium comprises one or more compounds of the formula T given above, which are preferably selected from the group of compounds of the formulae T21 to T23 and T25 to T27.

[0497] Particularly preferred are compounds of the formulae T21 to T23. Very particularly preferred are compounds of the following formulae:

[0498]

[0499]

[0500] kk) The medium comprises one or more compounds selected from the group of formulae DK9, DK10 and DK11 given above.

[0501] 11) The medium further comprises one or more compounds selected from the following formulae:

[0502]

[0503]

[0504] Where R 20 and X 20 Each independently has one of the meanings indicated above, and Y 20-23 Each independently represents H or F. 20 Preferably it is F, Cl, CF3, OCF3 or OCHF2. 20 Preferably it denotes alkyl, alkoxy, oxaalkyl, fluoroalkyl or alkenyl, each having up to 6 C atoms.

[0505] The mixtures according to the invention particularly preferably comprise one or more compounds of the formula XVIII-a,

[0506]

[0507] Where R 20 has the meaning indicated above. 20 Preferably it is straight-chain alkyl, in particular ethyl, n-propyl, n-butyl and n-pentyl, and very particularly preferably n-propyl. The compounds of the formula XVIII, in particular the formula XVIII-a, are preferably used in the mixture according to the invention in an amount of 0.5 to 20% by weight, particularly preferably 1 to 15% by weight.

[0508] mm) the medium further comprises one or more compounds of the formula XIX,

[0509]

[0510] Where R 20 , X 20 and Y 20-25 has the meaning indicated in formula I, s represents 0 or 1, and

[0511] express

[0512] In Formula XIX, X 20 It may also represent an alkyl radical having 1 to 6 C atoms or an alkoxy radical having 1 to 6 C atoms. The alkyl or alkoxy radical is preferably straight-chain.

[0513] R 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably F;

[0514] - The compound of formula XIX is preferably selected from the following formulae:

[0515]

[0516]

[0517] Where R 20 , X 20 and Y 20 has the meaning indicated above. 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably, F is represented, and Y 20 Preferably F;

[0518] Preferably

[0519] -R 20 is a straight-chain alkyl or alkenyl group having 2 to 6 C atoms;

[0520] nn) the medium comprises one or more compounds of the formulae G1 to G4 given above, which are preferably selected from G1 and G2, wherein alkyl represents C 1-6 -alkyl, L x represents H, and X represents F or Cl. In G2, X particularly preferably represents Cl.

[0521] oo) the medium comprises one or more compounds of the following formulae:

[0522]

[0523] Where R 20 and X 20 has the meaning indicated above. 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F. The medium according to the invention particularly preferably comprises one or more compounds of the formula XXII, in which X 20 Preferably it represents F. The compounds of the formulae XX-XXII are preferably used in the mixtures according to the invention in an amount of 1 to 20% by weight, particularly preferably 1 to 15% by weight. Particularly preferably, the mixture comprises at least one compound of the formula XXII.

[0524] pp) the medium comprises one or more compounds of the following formulae:

[0525]

[0526] Where R 20 and X 20 has the meaning indicated above. 20 Preferably, X represents an alkyl radical having 1 to 6 C atoms. 20 Preferably represents F. The medium according to the invention particularly preferably comprises one or more compounds of the formula M-1, in which X 20 Preferably it represents F. The compounds of the formulae M-1 to M-3 are preferably used in the mixtures according to the invention in an amount of 1 to 20% by weight, particularly preferably 1 to 15% by weight.

[0527] Other preferred embodiments are indicated below:

[0528] qq) the medium comprises two or more compounds of formula XII, in particular compounds of formula XIIe;

[0529] rr) the medium contains 2 to 30% by weight, preferably 3 to 20% by weight, particularly preferably 3 to 15% by weight, of a compound of the formula XII;

[0530] ss) the medium comprises, in addition to the compound of formula XII, a further compound selected from the group of compounds of formulae II, III, IX-XIII, XVII and XVIII;

[0531] tt) the proportion of the compounds of formula II, III, IX-XI, XIII, XVII and XVIII in the overall mixture is 40% to 95% by weight;

[0532] uu) the medium contains 10 to 50% by weight, particularly preferably 12 to 40% by weight, of a compound of the formula II and / or formula III;

[0533] vv) the medium contains 20 to 70% by weight, particularly preferably 25 to 65% by weight, of a compound of the formula IX to XIII;

[0534] ww) the medium contains 4 to 30% by weight, particularly preferably 5 to 20% by weight, of a compound of the formula XVII;

[0535] xx) the medium contains 1 to 20% by weight, particularly preferably 2 to 15% by weight, of a compound of the formula XVIII;

[0536] yy) the medium comprises at least two compounds of the following formulae:

[0537]

[0538] zz) the medium comprises at least two compounds of the following formulae:

[0539]

[0540] aaa) The medium comprises at least two compounds of the formula XIIa and at least two compounds of the formula XIIe.

[0541] bbb) medium comprises at least one compound of the formula XIIa and at least one compound of the formula XIIe and at least one compound of the formula IIIa.

[0542] ccc) medium comprises at least two compounds of the formula XIIa and at least two compounds of the formula XIIe and at least one compound of the formula IIIa.

[0543] ddd) medium comprises in total ≥ 25% by weight, preferably ≥ 30% by weight, of one or more compounds of the formula XII.

[0544] eee) the medium contains ≥20% by weight, preferably ≥24% by weight, preferably 25 to 60% by weight, of a compound of the formula ZK3, in particular a compound of the formula ZK3a,

[0545]

[0546] fff) the medium comprises at least one compound selected from the group consisting of compounds ZK3a, ZK3b and ZK3c, preferably a combination of ZK3a and compound ZK3d

[0547]

[0548] ggg) medium comprises at least one compound of formula DPGU-nF.

[0549] hhh) The medium comprises at least one compound of the formula CDUQU-nF.

[0550] iii) the medium comprises at least one compound of formula CPU-n-OXF.

[0551] jjj) The medium comprises at least one compound of formula CPGU-3-OT.

[0552] kkk) The medium comprises at least one compound of formula PPGU-nF.

[0553] 111) The medium comprises at least one compound of the formula PGP-nm, preferably two or three compounds.

[0554] mmm) medium comprises at least one compound of the formula PGP-2-2V having the structure

[0555]

[0556] In a preferred embodiment, the liquid-crystal mixture according to the invention further comprises a polymerisable component C) comprising one or more polymerisable compounds.

[0557] The polymerizable compound may be selected from isotropic or mesogenic polymerizable compounds known to those skilled in the art.

[0558] Preferably, the polymerizable component C) comprises one or more polymerizable compounds of the formula P,

[0559] P a -Sp a -(A p )-R b P

[0560] The various groups have the following meanings:

[0561] P a represents a polymerizable group, preferably selected from acrylate, methacrylate, ethylacrylate, fluoroacrylate, vinyloxy, chloroacrylate, oxetanyl or epoxy,

[0562] Sp a represents a spacer group or a single bond,

[0563] A p is a group selected from the following formulae,

[0564]

[0565]

[0566] It is optionally substituted by one or more groups L a replace,

[0567] L ais, identically or differently on each occurrence, F, Cl, -CN, P-Sp- 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 way that the O- and / or S-atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by F or Cl, and

[0568] R b For the group

[0569]

[0570] Preferred spacer groups Sp a is selected from the formula Sp"-X" such that the groups P-Sp- and P a / b -Sp a / b - respectively conform to the formula P-Sp"-X"- and P a / b -Sp"-X"-, where

[0571] Sp" denotes an alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, wherein, in addition, one or more non-adjacent CH2 groups may each independently of one another be substituted by -O-, -S-, -NH-, -N(R)-, -S-, -NH-, -NH- or -N(R)- in such a way that the O and / or S atoms are not directly connected to one another. 0 )-、-Si(R 00 R 000 )-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N(R 00 )-CO-O-、-O-CO-N(R 00 )-、-N(R 00 )-CO-N(R 00 )-, -CH=CH- or -C≡C-,

[0572] X" means -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 00 )-、-N(R 00 )-CO-、-N(R 00 )-CO-N(R 00 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -、-CY3 =CY 4 -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond, preferably a single bond,

[0573] R 0 , R 00 and R 000 each independently of one another represents H or an alkyl group having 1 to 12 C atoms, and

[0574] Y 3 and Y 4 Each of them, identically or differently, represents H, F, Cl or CN.

[0575] X" is preferably -O-, -S-, -CO-, -C(O)O-, -OC(O)-, -OC(O)O-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 0 - or single key.

[0576] Typical spacer groups -Sp" are, for example, single bonds, -(CH2) p1 -、-(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 00 R 000 -O) p1 -, wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 00 and R 000 has the meaning indicated above.

[0577] Particularly preferred groups -Sp"-X"- are single bonds, -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -O-CO-O-, wherein p1 and q1 have the meanings indicated above.

[0578] Particularly preferred radicals Sp" in each case are, for example, straight-chain methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, vinylene, propenylene and butenylene.

[0579] Particularly preferred monomers of formula P are as follows:

[0580]

[0581]

[0582] Among them, P, Sp and L have specific a 、Sp a or L a have the meanings given in formula P,

[0583] r1, r3, r7 are independently 0, 1, 2 or 3,

[0584] r2 is 0, 1, 2, 3, or 4,

[0585] r4, r5, r6 are independently 0, 1 or 2, and

[0586] R b For the group

[0587]

[0588] Very preferred are compounds of the formulae P1, P2 and P5.

[0589] Very preferred compounds of formula I are selected from the following sub-formulae:

[0590]

[0591] Among them, P, Sp and R b has the meaning given above or below under formula P, and

[0592] L a and L b Each and independently has a a one of the meanings given and preferably, identically or differently on each occurrence, is F, Cl, -CN, P-Sp- or straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to one another, and in which one or more H atoms are each optionally replaced by F or Cl, and

[0593] Very preferred are compounds of formula P1-0, which are the following compounds:

[0594]

[0595] The compounds of formula P and its subformulae used in the present invention are prepared by methods known per se, as described in the literature (e.g. in standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), specifically under reaction conditions known and suitable for the reaction. Variants known per se can also be used here, which are not mentioned in more detail here.

[0596] If only the photoreactive component A) without any polymerizable component C) is used, a known problem with these materials is that they form very thin layers, with thicknesses in the range of 5-20 nm. For some applications, such thin layers may not be sufficient to pass the rigorous reliability tests required by the display industry. Typically, these tests may include, but are not limited to, pressure or pressure drop tests and / or thermal stresses. Such tests are regularly performed on PI-based alignment layers, which in some cases have typically been subjected to a coating and a two-step thermal curing process to provide a thick (60-80 nm) layer with strong mechanical properties.

[0597] When using compounds of formula P together with compounds of formula I, an increase in layer thickness from about 10 nm to values ​​of 20-30 nm can be observed compared to layers derived only from compounds of formula I. This can be confirmed and measured by AFM techniques known to those skilled in the art.

[0598] Another common test in the display industry is the surface "hardness". An abrasive object is thus moved over the surface to see if any deformation or visible damage is caused. For thin layers, it is very difficult to pass such a hardness test because they are generally more susceptible to contact damage. In addition to hardness, another consideration is the long-term reliability test of parameters such as voltage holding ratio (VHR). Since surfactants and other chemicals are used in the glass cleaning process, there is a risk that these substances may "leak" through the (photo) alignment layer during the service life of the product. This may cause the VHR to drop and significantly reduce the display quality. In this regard, the use of LC mixtures comprising a photoreactive component A) (which comprises one or more compounds of formula I) and a polymerizable component C) (which comprises one or more compounds of formula P) shows significant advantages in terms of reliability issues compared to LC mixtures comprising a photoreactive component A) (which comprises one or more compounds of formula I) alone or even a polymerizable component C) in combination with one or more polymerizable liquid crystal compounds.

[0599] It has further surprisingly been found that the combination of a photoreactive component A) with a polymerizable component C) leads to an advantageous dark state.

[0600] The amount of polymerizable component C) in the LC mixture as a whole is preferably 0.1-5%, more preferably 0.3-3%, in particular 0.5-2%.

[0601] The amount of one or more compounds of formula P in the polymerizable component C) as a whole is preferably 50-100%, more preferably 75-100%, in particular 90-100%, in particular the polymerizable component C consists of one, two or more compounds of formula P.

[0602] The polymerizable compounds of the formula I and P are also suitable for polymerization without initiators, which is accompanied by a number of advantages, such as lower material costs and, in particular, reduced contamination of the LC medium by possible residual amounts of initiators or their degradation products. The polymerization can therefore also be carried out without addition of initiators. Therefore, in a preferred embodiment, the LC medium does not contain a polymerization initiator.

[0603] The polymerizable component C) or the LC medium as a whole may also comprise one or more stabilizers in order to prevent undesired spontaneous polymerization of the RM, for example during storage or transport. Suitable types and amounts of stabilizers are known to the person skilled in the art and are described in the literature. Particularly suitable are stabilizers, for example from Commercially available stabilizers of the TUNA series (BASF SE), for example 1076. If a stabilizer is used, its proportion is preferably 10 ppm to 10,000 ppm, particularly preferably 50 ppm to 1000 ppm, based on the total amount of RM or polymerizable components.

[0604] The medium according to the invention preferably comprises 0.01-10%, particularly preferably 0.05-7.5% and most preferably 0.1-5% of a compound of component C) comprising a compound of the formula P according to the invention. The medium preferably comprises one, two or three, more preferably one or two and most preferably one compound of the formula P according to the invention.

[0605] With the aid of suitable additives, the liquid-crystal phases according to the invention can be modified so that they can be used in all types of liquid-crystal display elements disclosed to date. Additives of this type are known to the person skilled in the art and are described in detail in the literature (H. Kelker / R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes can be added for the production of colored guest-host systems or substances can be added to change the dielectric anisotropy, viscosity and / or alignment of the nematic phase.

[0606] The media according to the invention are prepared in a manner conventional per se. Typically, the components are dissolved in one another, preferably at elevated temperature.

[0607] Accordingly, the present invention further relates to a process for producing an LC medium according to the invention comprising the step of mixing one or more compounds of the formula I with a liquid-crystalline component B) as described above comprising one or more mesogenic or liquid-crystalline compounds.

[0608] The present invention further relates to a method for preparing a liquid crystal display, comprising at least the following steps:

[0609] Providing a first substrate, the first substrate comprising a pixel electrode and a common electrode for generating an electric field substantially parallel to a surface of the first substrate in a pixel area;

[0610] Providing a second substrate, wherein the second substrate is arranged opposite to the first substrate;

[0611] inserting a liquid crystal mixture between the first substrate and the second substrate, the liquid crystal mixture comprising one or more compounds of formula I, component B) and component C);

[0612] Illuminating the LCD with linearly polarized light to induce photo-alignment of the liquid crystal;

[0613] The polymerizable compound of the liquid crystal mixture is cured by irradiation with ultraviolet light or visible light having a wavelength of 450 nm or less.

[0614] The invention further relates to the use of the liquid-crystal mixtures according to the invention for producing liquid-crystal displays.

[0615] The invention further relates to a liquid crystal display manufactured by the method described above.

[0616] Hereinafter, the production method according to the present invention is described in more detail.

[0617] The first substrate comprises a pixel electrode and a common electrode for generating an electric field substantially parallel to the surface of the first substrate in the pixel area. Different kinds of displays with at least two electrodes on one substrate are known to the person skilled in the art, the most important difference being whether both the pixel electrode and the common electrode are structured (which is typical for IPS displays) or whether only the pixel electrode is structured and the common electrode is unstructured, which is the case for FFS displays.

[0618] It will be appreciated that the invention relates to any kind of electrode configuration suitable for generating an electric field substantially parallel to the surface of the first substrate in the pixel region; in the above, ie IPS and FFS displays.

[0619] The method according to the invention is independent of the type of substrate or surface material with which the liquid crystal mixture according to the invention is contacted during and after the method. Examples of materials for substrates or surfaces include polyimide, indium tin oxide (ITO), indium zinc oxide (IZO), silicon nitride (SiN x ) and an organic polymer of silicon dioxide (SiO2). The method is particularly suitable for use in displays containing substrates that do not have a polyimide layer on one or more of the surfaces in contact with the liquid crystal.

[0620] Where one or more of the substrates contain a polyimide layer, the polyimide may be rubbed or unrubbed, preferably unrubbed.

[0621] The present invention therefore relates to a display produced by the process according to the invention, wherein the substrate comprises a rubbed or unrubbed polyimide layer, preferably an unrubbed polyimide layer.

[0622] The invention further relates to a display produced by the method according to the invention, wherein neither or only one of the top and bottom substrates contains a polyimide layer.

[0623] In one embodiment of the present invention, the liquid crystal composition is injected between the first and second substrates or filled into the box by capillary force after the first and second substrates are combined. In an alternative embodiment, the liquid crystal composition can be inserted between the first and second substrates by combining the second substrate to the first substrate after the liquid crystal composition is loaded on the first substrate. Preferably, the liquid crystal is dispensed dropwise onto the first substrate by a method called "one drop filling method" (ODF) as described in, for example, JPS63-179323 and JPH10-239694 or by using an inkjet printing (IJP) method.

[0624] In a preferred embodiment, the method according to the invention contains a method step in which the liquid crystal inside the display panel is left to rest for a period of time in order to uniformly redistribute the liquid crystal medium inside the panel (referred to herein as "annealing").

[0625] However, it is also preferred that the annealing step is combined with a previous step such as edge sealant pre-curing. In this case, a "separate" annealing step may not be required at all.

[0626] To produce a display according to the invention, the photoreactive mesogens of formula I are preferably redistributed in the panel. After filling and assembly, the display panel is annealed for a period of between 1 minute and 3 hours, preferably between 2 minutes and 1 hour and most preferably between 5 minutes and 30 minutes. Annealing is preferably carried out at room temperature.

[0627] In alternative embodiments, annealing is performed at elevated temperature, preferably above 20°C and below 140°C, more preferably above 40°C and below 100°C and most preferably above 50°C and below 80°C.

[0628] In a preferred embodiment, one or more of the method steps of filling the display, annealing, photoaligning and curing the polymerizable compound are performed at a temperature above the clearing point of the liquid crystal host mixture.

[0629] During photo-alignment of the liquid crystals inside a liquid crystal panel, anisotropy is induced by exposing the display or the liquid crystal layer to linearly polarized light.

[0630] In a preferred embodiment of the invention, the photoreactive component A) comprising one or more compounds of the formula I is photoaligned in a first step using linearly polarized light and further cured in a second step using linearly polarized or unpolarized UV light. Component C) is also further cured in the second step.

[0631] In another preferred embodiment, the linearly polarized light applied according to the process of the invention is UV light which is able to simultaneously photoalign and photocure the photoreactive component A) comprising one or more compounds of the formula I, and photocure the polymerizable component C).

[0632] The photoalignment of the photoreactive compound of formula I and the curing of the polymerizable groups of the compound of formula I and the optional curing of the polymerizable compound of formula P can be carried out simultaneously or stepwise, preferably stepwise. In case the method is split into different steps, the individual steps can be carried out at the same temperature or at different temperatures.

[0633] After the photoalignment and curing step(s), a so-called "post-curing" step may optionally be carried out at low temperature by irradiation with UV light and / or visible light (both linear or unpolarized) in order to remove unreacted polymerizable compounds. This post-curing is preferably carried out at a temperature above 0°C and below the clearing point of the LC mixture used, preferably at 20°C and below 60°C, and most preferably above 20°C and below 40°C.

[0634] The polymerizable compound (if the polymerizable compound contains two or more polymerizable groups) is optionally polymerized or crosslinked by applying an electric field. The polymerization can be performed in one or more steps.

[0635] Suitable and preferred polymerization methods for component C) are, for example, thermal polymerization or photopolymerization, preferably photopolymerization, in particular UV photopolymerization. Optionally, one or more initiators may also be added in this context. Suitable conditions for polymerization and suitable types and amounts of initiators are known to the person skilled in the art and are described in the literature. Suitable for free-radical polymerization are, for example, commercially available photoinitiators or (BASF SE). If an initiator is used, its proportion is preferably from 0.001% to 5% by weight, particularly preferably from 0.001% to 1% by weight.

[0636] The invention furthermore relates to an electro-optical liquid crystal display element comprising a liquid crystal medium according to the invention, which is preferably homogeneously aligned.In a preferred embodiment, the liquid crystal display has IPS or FFS mode.

[0637] Further combinations of embodiments and variants of the invention according to the present description result from the claims.

[0638] The present invention is explained in more detail below with reference to working examples, but is not intended to be limited thereto. A person skilled in the art will be able to gather working details not given in detail in the general description from the examples, generalize the working details according to general expert knowledge and apply them to specific problems.

[0639] In addition to common and familiar abbreviations, the following abbreviations are used:

[0640] C: crystalline phase; N: nematic phase; Sm: smectic phase; I: isotropic phase. The numbers between these symbols show the transition temperatures of the substances involved.

[0641] Unless otherwise indicated, temperature data are in °C.

[0642] The physical, physicochemical or electro-optical parameters are determined by generally known methods, such as, inter alia, the manual "Merck Liquid Crystals - -Physicial properties of Liquid Crystals–Description of the Measurement Methods", 1998, Merck KGaA, Darmstadt.

[0643] In the above and below, Δn represents the optical anisotropy (589 nm, 20° C.) and Δε

[0644] It represents dielectric anisotropy (1kHz, 20°C). Dielectric anisotropy Δε is measured at 20°C and 1kHz. Optical anisotropy Δn is measured at 20°C and a wavelength of 589.3nm.

[0645] The Δε and Δn values ​​and the rotational viscosity (γ1) of the compounds according to the invention are obtained by linear extrapolation from liquid crystal mixtures consisting of 5% to 10% of the respective compound according to the invention and 90% to 95% of the commercially available liquid crystal mixtures ZLI-2857 (for Δε) or ZLI-4792 (for Δn, γ1) (mixtures, Merck KGaA, Darmstadt).

[0646] The compounds used in the present invention are prepared by methods known per se, as described in the literature (e.g. in standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), specifically under reaction conditions known and suitable for the reaction. Variants known per se can also be used here, which are not mentioned in more detail here.

[0647] In the present invention and in particular in the following examples, the structures of the mesogenic compounds are indicated by means of abbreviations (also called acronyms). In these acronyms, the chemical formulae are abbreviated as follows using the following Tables A to C. All groups C n H 2n+1 , C m H 2m+1 and C l H 2l+1 or C n H 2n-1 , C m H 2m-1 and C l H 2l-1 = represents a straight chain alkyl or alkenyl, preferably 1E-alkenyl, each of which has n, m and 1 C atoms, respectively. Table A lists the codes for the ring elements of the core structure of the compound, while Table B shows the linking groups. Table C gives the meaning of the codes for the left-hand or right-hand terminal groups. The acronyms consist of the code for the ring element with the optional linking group, followed by the first hyphen and the code for the left-hand terminal group and the second hyphen and the code for the right-hand terminal group. Table D shows the illustrative structures of the compounds and their corresponding abbreviations.

[0648] Table A: Ring elements

[0649]

[0650]

[0651] Table B: Linking Groups

[0652]

[0653]

[0654] Table C: End Groups

[0655]

[0656]

[0657] where n and m each represent an integer, and the three dots "..." are placeholders for other abbreviations from this table.

[0658] The following table shows illustrative structures and their corresponding abbreviations. These are shown to illustrate the meaning of the abbreviation conventions. In addition, they represent compounds that are preferably used.

[0659] Table D: Illustrative Structure

[0660]

[0661]

[0662]

[0663]

[0664]

[0665]

[0666]

[0667]

[0668]

[0669]

[0670]

[0671]

[0672]

[0673]

[0674]

[0675]

[0676]

[0677]

[0678]

[0679] Here, n, m and l preferably represent 1 to 7 independently of one another.

[0680] The following table (Table E) shows illustrative compounds that can be used as additional stabilizers in the mesogenic medium according to the present invention.

[0681] Table E

[0682] Table E shows possible stabilizers which can be added to the LC media according to the invention.

[0683] (here n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and the terminal methyl group is not shown).

[0684]

[0685]

[0686]

[0687]

[0688]

[0689]

[0690] The LC medium preferably comprises 0% to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 1 ppm to 1% by weight, of stabilizer.

[0691] Table F below shows illustrative compounds which can preferably be used as chiral dopants in the mesogenic medium according to the invention.

[0692] Table F

[0693]

[0694]

[0695]

[0696]

[0697] In a preferred embodiment of the present invention, the mesogenic medium comprises one or more compounds selected from the group of Table F compounds.

[0698] The mesogenic medium according to the present application preferably comprises two or more, preferably four or more, compounds selected from the group consisting of the compounds of the above tables.

[0699] The liquid-crystalline media according to the invention preferably comprise

[0700] 7 or more, preferably 8 or more, individual compounds having preferably 3 or more, particularly preferably 4 or more different formulae selected from the group of compounds of Table D.

[0701] Hereinafter, the present invention will be described in more detail and specifically with reference to Examples, which however are not intended to limit the present invention. DETAILED DESCRIPTION

[0702] Example

[0703] The polymerizable compound of formula P used:

[0704] P-1

[0705] The photoreactive compound of formula I used is:

[0706] I-1

[0707] Polymerizable compounds used for comparison

[0708] RM-1

[0709] RM-2

[0710] Nematic host mixture used

[0711] Nematic LC host mixture N-1 was prepared as indicated in the following table:

[0712] Mixture N-1:

[0713]

[0714] condition

[0715] All examples detailed in these examples were subjected to standard conditions for SA-IPS / FFS materials. In detail, the wire grid polarizer was followed by an Omnicure S2000 mercury lamp UV source using 35 mW cm -2 of exposure power. The photoreactive compound I-1 requires exposure using a 360nm cutoff filter. As stated in the datasheet, exposure times typically range from 30 seconds to 180 seconds. All samples were exposed to the same box maintained at 100°C. A second UV exposure was then performed at the same power at room temperature for a given time without the use of a polarizer. The box used was a 6um PI-free 1cmx1cm ITO electrode area, and the glass type was Corning's Eagle XG AF glass (0.7mm thick).

[0716] Comparative Example

[0717] The following LC mixtures were prepared from the nematic host mixture N-1 listed above and the given amounts of the photoreactive compound (I) and the polymerizable compound (P) were mixed according to the composition given in the following table.

[0718]

[0719] After treatment, x10 objective microscope pictures were taken under the same conditions for all boxes between crossed polarizers and the sample was rotated to obtain the best dark state. The average gray value of each picture is then a measure of the quality of the dark state. The following table summarizes the results of the measurements.

[0720] Mixture composition Dark State CM 1 0.18 CM 2 0.18 CM 3 0.20 CM 4 (reference) 0.12

[0721] From the table, it can be seen that the dark state is negatively affected by using RM-1 or RM-2 compared to the reference cell.

[0722] Working Example

[0723] The following LC mixtures were prepared from the nematic host mixture N-1 listed above and the given amounts of the photoreactive compound (I) and the polymerizable compound (P) were mixed according to the composition given in the following table.

[0724]

[0725] Mixture Examples Dark State CM 5 (reference) 0.92 M 1 0.58 M 2 0.51 M 3 0.49 CM 6 (reference) 0.44 M 4 0.41 M 5 0.41 M 6 0.51

[0726] The table shows that especially at a concentration of 0.7% of P-1, there is still no negative impact on the dark state quality. This value does not change after the second UV step at room temperature. This remains valid whether a broadband UV source with a 360 nm cut-off filter is used, or a B or C lamp source is used.

[0727] The following LC mixtures were prepared from the nematic host mixture N-1 listed above and the given amounts of the photoreactive compound (I) and the polymerizable compound (P) were mixed according to the composition given in the following table.

[0728]

[0729] The LC mixture was capillary filled at room temperature by using capillary action, annealed at 100°C for 1 h, and then irradiated for 1 min at the same temperature using linearly polarized UV light (35 mW / cm2) from an Omnicure S2000 mercury lamp with a built-in 320-500 nm filter, using an additional 360 nm long pass filter (cutting off the shorter wavelengths of 320-360 nm). The cell was then cooled to room temperature and then irradiated for 5 min with linearly polarized UV light (35 mW / cm2) from an Omnicure S2000 mercury lamp with a built-in 320-500 nm filter. After the first UV step and the second UV step, the VHR was initially investigated using a Toyo LCM-1 LC material properties test system. The measurement of VHR was performed as described in T. Jacob, U. Finkenzeller in "Merck Liquid Crystals-Physical properties of Liquid Crystals", 1997.

[0730] VHR measured at 60°C, 60Hz and 1V:

[0731]

[0732] VHR measured at 60°C, 3Hz and 1V:

[0733]

[0734]

Claims

1. A liquid crystal mixture comprising a photoalignment component A) comprising one or more photoreactive mesogens of formula I, in A 11 represents a group selected from the following group: a) the group consisting of 1,4-phenylene and 1,3-phenylene, in addition, one or two CH groups are optionally replaced by N, and in addition, one or more H atoms are optionally replaced by L, b) a group selected from the group consisting of, in, In addition, one or more H atoms in these groups are optionally replaced by L, and / or one or more double bonds are optionally replaced by single bonds, and / or one or more CH groups are optionally replaced by N, A each independently has a specific 11 One of the meanings, or a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene, wherein, in addition, one or more non-adjacent CH2 groups are optionally replaced by -O- and / or -S-, and wherein, in addition, one or more H atoms are optionally replaced by F, or b) tetrahydropyran-2,5-diyl, 1,3-di the group consisting of alkane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which is optionally also mono- or polysubstituted by L, L, in each occurrence, identically or differently, represents -OH, -F, -Cl, -Br, -I, -CN, -NO2, SF5, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R z )2, -C(=O)R z 、-N(R z )2, optionally substituted silyl, optionally substituted aryl having 6-20 C atoms, or linear or branched or cyclic alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1-25 C atoms, or X 21 -Sp 21 -R 21 , M represents -O-, -S-, -CH2-, -CHR z -or-CR y R z -, R y and R z each independently of one another represents H, CN, F or alkyl having 1 to 12 C atoms, wherein one or more H atoms are optionally replaced by F, Y 11 and Y 12 each independently of one another represents H, F, phenyl or optionally fluorinated alkyl having 1 to 12 C atoms, Z, independently of one another, represents at each occurrence a single bond, -COO-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -OCF2-, -CF2O-, -(CH2) n -, -CF2CF2-, -CH=CH-, -CF=CF-, -CH=CH-COO-, -OCO-CH=CH-, -CO-S-, -S-CO-, -CS-S-, -S-CS-, -S-CSS- or -C≡C-, n represents an integer from 2 to 8, o and p each and independently represent 0, 1 or 2, X 11 and X 21 represents, independently of one another at each occurrence, a single bond, -CO-O-, -O-CO-, -O-COO-, -O-, -CH=CH-, -C≡C-, -CF2-O-, -O-CF2-, -CF2-CF2-, -CH2-O-, -O-CH2-, -CO-S-, -S-CO-, -CS-S-, -S-CS-, -S-CSS- or -S-, Sp 11 and Sp 21 each and independently at each occurrence represents a single bond or a spacer group comprising 1 to 20 C atoms, wherein one or more non-adjacent and non-terminal CH2 groups are optionally also replaced by -O-, -S-, -NH-, -N(CH3)-, -CO-, -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O-, -CF2-, -CF2O-, -OCF2-, -C(OH)-, -CH(alkyl)-, -CH(alkenyl)-, -CH(alkoxy)-, -CH(oxaalkyl)-, -CH=CH- or -C≡C-, however in such a way that no two O atoms are adjacent to one another and no two groups selected from -O-CO-, -S-CO-, -O-COO-, -CO-S-, -CO-O- and -CH=CH- are adjacent to one another, R 11 represents P, R 21 represents P, halogen, CN, optionally fluorinated alkyl or alkenyl having up to 15 C atoms, wherein one or more non-adjacent -CH2- groups are optionally replaced by -O-, -S-, -CO-, -C(O)O-, -OC(O)-, OC(O)-O-, P is each and independently of one another at each occurrence a polymerizable group, The liquid crystal component B), the "LC host mixture", comprises one or more nematic compounds, and The polymerizable component C) comprises one or more polymerizable compounds of formula P, P a -Sp a -(THE p )-R b P The various groups have the following meanings: P a represents a polymerizable group, Sp a represents a spacer group or a single bond, A p is a group selected from the following formulae, It is optionally substituted by one or more groups L a replace, L a is, identically or differently on each occurrence, F, Cl, -CN, P-Sp- 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 way that the O and / or S atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by F or Cl, and R b For the group Wherein P represents a polymerizable group, and Sp represents a spacer group or a single bond.

2. A liquid crystal mixture according to claim 1, characterized in that The total concentration of the compounds of formula I in the mixture is in the range of 0.01-10 wt%.

3. A liquid crystal mixture according to claim 1 or 2, characterized in that The concentration of the polymerizable component C) is in the range of 0.1 to 5 wt%.

4. A liquid crystal mixture according to claim 1 or 2, characterized in that It comprises one or more compounds of formulae P1-0 to P1-7, Among them, P, Sp and R b Having P given under the formula P in claim 1 a 、Sp a and R b Meaning, and L a and L b when it occurs identically or differently, is F, Cl, -CN, P-Sp- or a straight-chain, branched or cyclic alkyl group 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 way that the O and / or S atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by F or Cl, wherein P represents a polymerizable group and Sp represents a spacer group or a single bond.

5. A liquid crystal mixture according to claim 1 or 2, characterized in that The LC host mixture has negative dielectric anisotropy.

6. A liquid crystal mixture according to claim 5, characterized in that The LC host mixture comprises one or more compounds selected from the following formulae: in a is 1 or 2, b is 0 or 1, express R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH2 groups are optionally replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another, Z x Indicates -CH=CH-, -CH2O-, -OCH2-, -CF2O-, -OCF2-, -O-, -CH2-, -CH2CH2- or a single bond, L 1-4 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

7. A liquid crystal mixture according to claim 1 or 2, characterized in that The LC host mixture has positive dielectric anisotropy.

8. A liquid crystal mixture according to claim 7, characterised in that The LC host mixture comprises one or more compounds selected from the group consisting of compounds of formula II and III, in R 20 each identically or differently represents a halogenated or unsubstituted alkyl or alkoxy radical having 1 to 15 C atoms, wherein one or more CH2 radicals in these radicals are optionally each independently of one another in such a way that the O atoms are not directly connected to one another by -C≡C-, -CF2O-, -CH=CH-, -O-, -CO-O- or -O-CO-, X 20 each identically or differently represents F, Cl, CN, SF5, SCN, NCS, halogenated alkyl, halogenated alkenyl, halogenated alkoxy or halogenated alkenyloxy, each having up to 6 C atoms, and Y 20-24 each identically or differently represents H or F, W represents H or methyl, 9. A liquid crystal mixture according to claim 7, characterized in that It comprises one or more compounds selected from the group consisting of compounds of formulae XI and XII, Where R 20 , X 20 , W and Y 20-23 has the meaning indicated in formula III in claim 8, and Each independently expresses express 10. A liquid crystal mixture according to claim 1 or 2, characterized in that The LC host mixture comprises one or more compounds of the following formula: The various groups have the following meanings: express express R 3 and R 4 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein one or two non-adjacent CH2 groups are optionally replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another, Z y Represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO- O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond.

11. A liquid crystal mixture according to claim 1 or 2, characterized in that The LC host mixture comprises one or more compounds of the formula, Among them, the propyl, butyl and pentyl groups are straight chain groups.

12. A liquid crystal mixture according to claim 1 or 2, characterized in that The LC host mixture comprises one or more compounds selected from the following formulae: Among them, alkyl and alkyl * each independently represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and akenyl * each independently of one another represents a straight-chain alkenyl group having 2 to 6 C atoms.

13. A liquid crystal mixture according to claim 1 or 2, characterized in that The LC host mixture comprises one or more compounds selected from the following formulae: Among them, alkyl * represents an alkyl group having 1 to 6 C atoms.

14. Use of a liquid crystal mixture according to any one of claims 1 to 13 for producing liquid crystal displays.

15. A method for manufacturing a liquid crystal display, comprising at least the following steps: providing a first substrate, the first substrate comprising a pixel electrode and a common electrode for generating an electric field substantially parallel to a surface of the first substrate in a pixel region; Providing a second substrate, wherein the second substrate is arranged opposite to the first substrate; Insertion of a liquid crystal mixture according to any one of claims 1 to 13; irradiating the liquid crystal mixture with linearly polarized light to induce photo-alignment of the liquid crystal; The polymerizable compound of the liquid crystal mixture is cured by irradiation with ultraviolet light or visible light having a wavelength of 450 nm or less.

16. The method according to claim 15, characterized in that The linearly polarized light is ultraviolet light or visible light having a wavelength of 450 nm or less.

17. A display obtainable by a method according to claim 15 or 16.

18. A display according to claim 17, wherein the LC host mixture is homogeneously aligned in the absence of an applied electric field.

19. A display according to claim 17 or 18, wherein the display is an IPS or FFS display.

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