Liquid crystal medium

Abstract

The present invention relates to a liquid crystal (LC) medium, optionally comprising polymerizable compounds, to its use for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the polymer sustained alignment (PSA) type, and to LC displays containing it, especially PSA displays, and in particular to LC displays having a narrow bezel.

Description

TECHNICAL FIELD

[0001] The present invention relates to a liquid crystal (LC) medium and the use of an LC medium for optical, electro-optical and electronic purposes, in particular in LC displays, especially in IPS, FFS, VA or PS-VA displays. BACKGROUND ART

[0002] One type of liquid crystal display (LCD) currently in use is the TN ("twisted nematic") mode. However, a disadvantage of TN LCDs is that the contrast has a strong dependence on the viewing angle.

[0003] In addition, so-called VA (vertical alignment) displays with a wider viewing angle are known. The LC cell of a VA display contains a layer of LC medium between two transparent electrodes, where the LC medium typically has a negative dielectric anisotropy. In the power-off state, the molecules of the LC layer are aligned perpendicular to the electrode surface (vertically) or have an inclined vertical alignment. When a voltage is applied to the two electrodes, realignment of the LC molecules parallel to the electrode surface occurs.

[0004] In addition, OCB ("optically compensated bend") displays are known, which are based on the birefringence effect and have an LC layer (which has a so-called "bend" alignment and typically a positive dielectric anisotropy). When a voltage is applied, realignment of the LC molecules perpendicular to the electrode surface occurs. In addition, OCB displays typically contain one or more birefringent optical retardation films to prevent undesired light transmissivity of the bent cell in the dark state. OCB displays have a wider viewing angle and a shorter response time compared to TN displays.

[0005] Also known are so-called IPS ("in-plane switching") displays, which contain an LC layer between two substrates, where the two electrodes are arranged only on one of the two substrates and preferably have an intermeshing comb structure. When a voltage is applied to the electrodes, an electric field with a significant component parallel to the LC layer is generated therebetween. This causes realignment of the LC molecules in the layer plane.

[0006] In addition, so-called FFS (fringe field switching) displays have been reported (see in particular S.H. 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-like manner and the other is unstructured. This results in a strong so-called "fringe field", i.e., a strong electric field close to the edges of the electrodes, and such an electric field in the entire cell, which has both a strong vertical component and a strong horizontal component. FFS displays have a small contrast viewing angle dependence. FFS displays typically contain an LC medium with positive dielectric anisotropy and an alignment layer, typically an alignment layer of polyimide, which provides planar alignment of the molecules of the LC medium.

[0007] FFS displays can be operated as active matrix or passive matrix displays. In the case of an active matrix display, 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 a passive matrix display, individual pixels are typically addressed according to multiplexing methods known in the prior art.

[0008] Furthermore, FFS displays have been disclosed (see S.H. Lee et al., Appl. Phys. Lett. 73(20), 1998, 2882-2883 and S.H. Lee et al., Liquid Crystals 39(9), 2012, 1141-1148), which have an electrode design and layer thickness similar to those of FFS displays, but include a layer of an LC medium with negative dielectric anisotropy instead of a layer of an LC medium with positive dielectric anisotropy. Compared with an LC medium with positive dielectric anisotropy, an LC medium with negative dielectric anisotropy exhibits a more favorable director orientation, which has less tilt and more twist in the orientation, and as a result, these displays have a higher transmittance. The display also includes an alignment layer, preferably polyimide provided on at least one substrate, which contacts the LC medium and induces planar alignment of the LC molecules of the LC medium. These displays are also referred to as "ultra-bright FFS (UB-FFS)" mode displays. These displays require an LC medium with high reliability.

[0009] The term "reliability" as used hereinafter means the quality of the performance of a display over a period of time and under different stress loads, such as light load, temperature, humidity, voltage, and includes display effects such as image sticking (surface and line image sticking), color mura, non-uniformity (yogore), etc., which are known to those skilled in the art of LC displays. As a standard parameter for classifying reliability, the voltage holding ratio (VHR) value is usually used, which is a measure for maintaining a constant voltage in a test display. Among other factors, a high VHR is a prerequisite for high reliability of the LC medium.

[0010] In newer types of VA displays, the homogeneous alignment of LC molecules is limited to a plurality of relatively small domains within the LC cell. There can be disclinations, also called tilted domains, between these domains. A VA display with tilted domains has a greater contrast and a viewing angle independence of grey shades compared to conventional VA displays. Additionally, this type of display is easier to manufacture because no additional electrode surface treatment (e.g., by rubbing) is required to align the molecules homogeneously in the on-state. Instead, the preferred direction of the tilt angle or pre-tilt angle is controlled by a special design of the electrodes.

[0011] In so-called MVA (Multi-Domain Vertical Alignment) displays, this is typically achieved by electrodes with protrusions that cause a local pre-tilt. Thereby, when a voltage is applied, the LC molecules are aligned parallel to the electrode surface in different, defined cell regions in different directions. Thereby, "controlled" switching is achieved and the formation of disturbing disclination lines is prevented. Although this arrangement improves the viewing angle of the display, it results in a reduction of its light transmittance. A further improvement of MVA uses protrusions only on one electrode side, while the opposite electrode has slits, which improves the light transmittance. The slit electrode generates a non-uniform electric field in the LC cell when a voltage is applied, meaning that controlled switching is still achieved. To further improve the light transmittance, the spacing between the slit and the protrusion can be increased, but this in turn leads to an increase in the response time. In so-called PVA ("Patterned VA"), the protrusions are made completely redundant because both electrodes are structured by slits on opposite sides, which results in increased contrast and improved light transmittance, but this is technically difficult and makes the display more sensitive to mechanical influences ("tapping", etc.). However, for many applications, such as monitors and especially TV screens, a shortening of the response time of the display as well as an improvement of the contrast and brightness (transmittance) of the display are required.

[0012] Another development is the so-called PS (“polymer sustained”) or PSA (“polymer sustained alignment”) display, for which the term “polymer stabilization” is also occasionally used. In these, a small amount (e.g., 0.3 wt%, typically <1 wt%) of one or more polymerizable compounds, preferably polymerizable monomeric compounds, is added to the LC medium, and after the LC medium is filled into the display, it is polymerized or crosslinked in situ (usually by UV photopolymerization), while optionally applying a voltage to the electrodes of the display. The polymerization is carried out at a temperature at which the LC medium exhibits a liquid crystal phase, usually at room temperature. Adding a polymerizable mesogen or liquid crystal compound (also called a reactive mesogen or “RM”) to the LC mixture has proven to be particularly suitable.

[0013] Unless otherwise specified, the term “PSA” is used hereinafter when referring to displays of the general polymer sustained alignment type, and “PS” is used when referring to specific display modes (such as PS-VA, PS-TN, etc.).

[0014] Furthermore, unless otherwise specified, the term “RM” is used hereinafter when referring to polymerizable mesogens or liquid crystal compounds.

[0015] At the same time, the PS(A) principle is being used in various conventional LC display modes. Thus, for example, PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, and PS-TN displays are known. The polymerization of the RM preferably occurs under an applied voltage in the case of PS-VA and PS-OCB displays, and occurs with or without, preferably without, an applied voltage in the case of PS-IPS displays. As can be verified in a test cell, the PS(A) method results in a pretilt in the cell. In the case of a PS-OCB display, for example, a bent structure can be stabilized such that a disclination voltage is not required or can be reduced. In the case of a PS-VA display, this pretilt has a positive effect on the response time. For a PS-VA display, standard MVA or PVA pixel and electrode layouts can be used. However, additionally, for example, it is also possible to manage with only one structured electrode side without protrusions, which significantly simplifies production and at the same time results in very good contrast and very good transmittance.

[0016] PS-VA displays are described, for example, in EP1 170 626 A2, US 6,861,107, US 7,169,449, US2004 / 0191428 A1, US 2006 / 0066793 A1, and US 2006 / 0103804 A1. PS-OCB displays are described, for example, in T-J-Chen et al., Jpn J Appl Phys 45, 2006, 2702-2704 and S H Kim, L-C-Chien, Jpn J ApplPhys 43, 2004, 7643-7647. PS-IPS-displays are described, for example, in US 6,177,972 and Appl Phys Lett1999, 75(21), 3264. PS-TN-displays are described, for example, in Optics Express 2004, 12(7), 1221.

[0017] Under the layer formed by phase separation and polymerization RM that induces the above-mentioned pretilt angle, PSA displays typically contain an alignment layer, such as an alignment layer of polyimide, which provides an initial alignment of LC molecules before the polymer stabilization step.

[0018] Friction polyimide layers have long been used as alignment layers. The friction method causes various problems, such as color difference, contamination, electrostatic discharge problems, residues, etc. Therefore, instead of friction polyimide layers, it is proposed to use polyimide layers prepared by photoalignment, using the photoinduced orientation order of the alignment surface. This can be achieved by means of polarized light, via photodecomposition, photodimerization, or photoisomerization.

[0019] However, there is still a need for a suitably derivatized polyimide layer containing photoreactive groups. Generally speaking, for the production of this polyimide layer, the workload and cost of treating polyimide and modifying bumps or polymer layers are relatively large.

[0020] In addition, it has been observed that the adverse interaction between the polyimide alignment layer and certain compounds of the LC medium usually reduces the resistance of the display. At the expense of display parameters (such as viewing angle dependence, contrast, and response time) that are intended to be improved by using such LC compounds, the number of suitable and available LC compounds is thus significantly reduced. Therefore, it is necessary to omit the polyimide alignment layer.

[0021] For some display modes, this is achieved by adding a self-aligning agent or additive to the LC medium, which in situ induces the required alignment, such as vertical or planar alignment, through a self-assembly mechanism. Thus, the alignment layer on one or both of the substrates can be omitted. These display modes are also referred to as "self-aligning" or "self-aligned" (SA) modes.

[0022] In SA displays, a small amount (usually 0.1% to 2.5%) of a self-aligning additive is added to the LC medium. Suitable self-aligning additives are, for example, compounds having an organic core group and one or more polar anchoring groups attached thereto, which can interact with the substrate surface such that the additive aligns on the substrate surface and also induces the desired alignment in the LC molecules. Preferred self-aligning additives include, for example, mesogenic groups and linear or branched alkyl side chains capped with one or more polar anchoring groups, the one or more polar anchoring groups being selected, for example, from hydroxyl, carboxyl, amino or thiol groups. The self-aligning additive may also contain one or more polymerizable groups that can be polymerized under similar conditions to those of the RM used in the PSA method.

[0023] SA-VA displays and SA-FFS displays have been disclosed to date. Suitable self-aligning additives for inducing vertical alignment, especially for use in SA-VA mode displays, are disclosed, for example, in US 2013 / 0182202 A1, US 2014 / 0138581 A1, US2015 / 0166890 A1 and US 2015 / 0252265 A1.

[0024] The SA mode can also be used in combination with the PSA mode. The LC medium of the display for this combined mode thus contains both one or more RMs and one or more self-aligning additives.

[0025] Similar to the above-described conventional LC displays, PSA displays can be operated as active matrix or passive matrix displays. In the case of active matrix displays, individual pixels are typically addressed through integrated non-linear active elements such as transistors (e.g., thin film transistors "TFTs"), while in the case of passive matrix displays, they are typically addressed through multiplexing methods known in the prior art.

[0026] PSA displays also include an alignment layer on one or both substrates forming the display cell. The alignment layer is typically applied to the electrodes (where such electrodes exist) such that it contacts the LC medium and induces an initial alignment of the LC molecules. The alignment layer also comprises or consists of, for example, polyimide, which can still be rubbed or can be prepared by photo-alignment methods.

[0027] Especially for monitors and particularly for TV applications, there is a continuing requirement for the optimization of the response time as well as the contrast and brightness (and thus also the transmittance) of liquid crystal displays. The PSA method can provide key advantages here. Especially in the case of PS-VA, PS-IPS and PS-FFS, a shortening of the response time related to the pretilt measurable in a test cell can be achieved without a significant detrimental effect on other parameters.

[0028] As the demand for LCDs grows and LCD technology develops, displays with favorable characteristics of being lighter and thinner have been designed, including a trend towards a slender design of the LCD from an aesthetic point of view, such as an LCD with a reduced bezel area. The demand for lightweight and slender displays with narrow bezels poses new challenges to product design and manufacturing.

[0029] An LCD device includes two substrates having electrodes and a liquid crystal layer located in a space surrounded by the substrates. The display of an image is achieved by changing the alignment of the liquid crystal by means of a voltage applied to the electrodes.

[0030] An LCD display is typically manufactured by adhesively bonding a first substrate having pixel electrodes, thin film transistors (TFTs), and other components to a second substrate including a common electrode using a sealant. The space surrounded by the substrates is filled with liquid crystal by capillary force or vacuum via a filling opening; subsequently, the filling opening is sealed using a sealant.

[0031] In recent years, as the size of liquid crystal displays has increased, the so-called "drop-down filling" process (ODF process) has been proposed as a process for mass production of liquid crystal displays (for example, see JPS63-179323 and JPH10-239694) in order to shorten the cycle time during production. This is a process for manufacturing a liquid crystal display, in which droplets of liquid crystal are applied to a substrate that is equipped with electrodes and is provided with a sealant around the edge. The second substrate equipped with electrodes is then installed in a vacuum, the sealant is partially cured by UV irradiation, and then completely cured by heat treatment. The two-step process consisting of UV curing and heat curing enables shortening of the duration of curing.

[0032] However, this method has the following disadvantages: the sealant in an uncured state comes into contact with the liquid crystal, and the components of the sealant can diffuse into the liquid crystal.

[0033] In the case of the ODF process, a distinction is made between three processes:

[0034] A heat curing process, a light curing process, and a light curing and heat curing process for curing the sealant for liquid crystal after bonding the two substrates together. The disadvantage of the heat curing process is that the liquid crystal expands and its viscosity decreases due to heating, which is favorable for mixing with the sealant.

[0035] In the photo-curing process, in each case, depending on the type of photo-polymerization initiator, a distinction is made between two types of sealants (those of the cationic polymerization type and those of the free-radical polymerization type). In the case of sealants of the cationic polymerization type, there is a problem of ions generated during photo-curing that can diffuse into the liquid crystal, which results in a decrease in the specific resistance of the liquid crystal. In the case of sealants of the free-radical polymerization type, there is a problem that the curing shrinkage is relatively large, which can lead to low bonding strength. Both types of sealants, namely the cationic polymerization type and the free-radical polymerization type, have such a common problem: the masked portions not irradiated with light remain uncured or only incompletely cured, for example, behind the metal contacts of the electronic components of the TFT array substrate of a liquid crystal display or behind the black matrix of the color filter substrate.

[0036] Therefore, it has been proven that the photo-curing and thermal-curing processes are particularly suitable for practice. It is characterized in that the sealant for the liquid crystal between the substrates is subjected to a primary curing by irradiation with light and then a secondary curing step by heat. In the photo-curing and thermal-curing processes, it is necessary that the liquid crystal is not contaminated before or after exposure to light or before or after heating. Specifically, measures for curing the above-mentioned masked areas and measures for preventing the diffusion of the sealant components during thermal curing are required.

[0037] A suitable starting point for the solution is to rapidly cure at a low temperature before the start of the mixing of the sealant and the liquid crystal, or to use components in the sealant that are less or not at all soluble in the liquid crystal. Rapid curing at a low temperature means that the life of the sealant is very short due to high reactivity, which actually represents the main problem. Therefore, it is preferable to use such a sealant that has a long life and includes components with low solubility in the liquid crystal.

[0038] For example, sealants for liquid crystal displays are disclosed in US2007 / 096056 A1, EP 1780587 A1, US 2003 / 0147034 A1 and EP 2381304A1.

[0039] The above-mentioned problem of damage to the liquid crystal during the curing of the sealant for the liquid crystal display is serious, especially if the liquid crystal itself includes polymerizable components, as is the case in the above-mentioned PS ("Polymer Sustaining") or PSA ("Polymer Sustaining Alignment") modes, where the polymerizable compounds are polymerized and crosslinked in situ.

[0040] The photo-initiators used in the sealant for the liquid crystal are particularly problematic because, after activation, they release the actual reactive free radicals that initiate or accelerate polymerization, and as small molecules, they have a high mobility and are generally easily soluble in the liquid crystal.

[0041] This problem has been solved, for example, in US2009 / 0147206, which proposed polymer photoinitiators that, due to their polyacrylate-based polymer structure, are intended to remain in the sealant during curing. The disadvantage here is that large polymer photoinitiators have low mobility and, due to the fact that they are prepared by polymerization of monomer precursors, the reactive types of initiators in particular are only difficult to obtain.

[0042] It is clear that the LC is exposed to various stresses during the production of the display, namely, heat, UV light, and reactive intermediates of the sealant. Ideally, the LC medium is first inert to the sealant components, since in all types of LC panels the LC will interact with the frame sealant during the production process, which can lead to edge non-uniformities. This edge non-uniformity becomes more visible when the bezel is narrower. Therefore, for narrow bezels, there is still a need for an LC mixture that shows little or no interaction with the frame sealant and thus little or no edge non-uniformity. Summary of the Invention

[0043] The present invention is based on the following object: to provide novel suitable materials in the LC medium, optionally including reactive mesogens (RM), for use in displays that do not have the above-mentioned disadvantages or have them to a reduced extent. In particular, there is still a need in the art for liquid crystal media with high reliability.

[0044] Furthermore, an object of the present invention is to provide alternative media in addition to the existing media known to those skilled in the art in order to expand the range of available materials that allow for more specific optimization of a particular display.

[0045] These objects are achieved according to the invention by the materials and processes described in the present application.

[0046] It has been found, surprisingly, that the use of the liquid crystal host described below allows the achievement of the advantageous effects described above. In particular, it has been recognized that the edge non-uniformity can be reduced to an acceptable level or even completely avoided by using the liquid crystal medium as claimed and described herein.

[0047] The medium according to the invention is further characterized by excellent compatibility with the ODF process, such that only negligible small or no droplet non-uniformities are observed. Similarly, the image sticking in the display according to the invention is at an acceptable level or absent.

[0048] The present invention relates to a liquid crystal medium comprising one or more compounds of formula I

[0049]

[0050] wherein

[0051] R 11 represents a straight-chain, branched-chain or cyclic alkyl group having 1 to 12 C atoms, or a straight-chain, branched-chain or cyclic alkenyl group having at most 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine, preferably a straight-chain, branched-chain or cyclic alkyl group having 1 to 12 C atoms,

[0052] R 12 represents a straight-chain, branched-chain or cyclic alkyl group having 1 to 12 C atoms or a straight-chain, branched-chain or cyclic alkoxy group having 1 to 11 C atoms, or a straight-chain, branched-chain or cyclic alkenyl group having at most 12 C atoms, preferably a straight-chain, branched-chain or cyclic alkyl group having 1 to 12 C atoms,

[0053] and

[0054] one or more compounds selected from the compounds of formulae IIA, IIB, IIC and IID,

[0055]

[0056]

[0057] wherein

[0058] R 2A , R 2B , R 2C

[0059] and R 2D each independently of one another represent H, an alkyl or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, wherein furthermore one or more CH2 groups in these groups may be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO- in such a way that the O atoms are not directly linked to one another,

[0060] L 1 to L 4 each independently of one another represent F, Cl, CF3 or CHF2,

[0061] Y represents H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H,

[0062] Z 2 , Z 2B and Z 2DEach independently represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O-

[0063] p represents 0, 1 or 2,

[0064] q represents 0 or 1, and

[0065] v represents 1, 2, 3, 4, 5, or 6,

[0066] and

[0067] one or more compounds of formula IVa, and

[0068] one or more compounds of formula IVb

[0069]

[0070] wherein

[0071] R 41 and R 42 each independently represents a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy having up to 12 C atoms, and

[0072] represents

[0073] Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8-, or -CF=CF-,

[0074] and

[0075] one or more compounds of formula V

[0076]

[0077] wherein

[0078] R 51 , R 52 represents an alkyl having 1 to 7 C atoms, an alkoxy having 1 to 7 C atoms, or an alkoxyalkyl, alkenyl or alkenoxy having 2 to 7 C atoms,

[0079] are the same or different and represent

[0080]

[0081]

[0082] Z 51 ,Z 52 each independently of one another represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and

[0083] n is 1 or 2.

[0084] The medium according to the invention is characterized by advantageous properties for applications in displays with a narrow border (in particular in combination with reactive mesogens for the production of polymer-stabilized displays in the PS-VA mode). The medium according to the invention enables displays with a narrow border to exhibit reduced or no edge non-uniformity while exhibiting overall advantageous properties, in particular for TVs or monitors, such as low rotational viscosity, high clearing temperature, wide nematic range and low threshold voltage.

[0085] Unless otherwise stated, the following definitions apply.

[0086] As used herein, alkyl is straight-chain, branched-chain or cyclic and has 1 to 15 C atoms, preferably straight-chain and, unless otherwise stated, has 1, 2, 3, 4, 5, 6 or 7 C atoms, and is thus preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl.

[0087] In this context, branched-chain alkyl is preferably isopropyl, sec-butyl, isobutyl, isopentyl, 2-methylhexyl or 2-ethylhexyl.

[0088] As used herein, cyclic alkyl refers to straight-chain or branched-chain alkyl or alkenyl having up to 12 C atoms, preferably alkyl having 1 to 7 C atoms, wherein the group CH2 is replaced by a carbocyclic ring having 3 to 5 C atoms, very preferably selected from the group consisting of: cyclopropyl, cyclobutyl, cyclopentyl and cyclopentenyl, cyclopropylalkyl, cyclobutylalkyl, cyclopentylalkyl and cyclopentenylalkyl, methylcyclopropylalkyl, methylcyclobutylalkyl, methylcyclopentylalkyl and methylcyclopentenylalkyl, in particular cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl and cyclopentenylmethyl.

[0089] In this context, alkoxy is straight-chain or branched-chain and contains 1 to 15 C atoms. It is preferably straight-chain and, unless otherwise stated, has 1, 2, 3, 4, 5, 6 or 7 C atoms, and is thus preferably methoxy, ethoxy, n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy or n-heptyloxy.

[0090] In the present text, the alkenyl group is preferably an alkenyl group having 2 to 15 C atoms, which is straight-chain or branched and contains at least one C═C double bond. It is preferably straight-chain and has 2 to 7 C atoms. Thus, it is preferably vinyl, prop-1- or -2-enyl, but-1-, 2- or 3-enyl, pent-1-, 2-, 3- or 4-enyl, hex-1-, -2-, -3-, 4- or 5-enyl, hept-1-, -2-, -3-, 4-, 5- or 6-enyl. If the two C atoms of the C═C double bond are substituted, the alkenyl group can be in the form of E and / or Z isomers (trans / cis). Generally, the corresponding E isomer is preferred. Among the alkenyl groups, prop-2-enyl, but-2- and 3-enyl and pent-3- and 4-enyl are particularly preferred.

[0091] In the present text, the alkynyl group refers to an alkynyl group having 2 to 15 carbon atoms, which is straight-chain or branched and contains at least one C≡C triple bond. 1- and 2-propynyl and 1-, 2- and 3-butynyl are preferred.

[0092] The compounds of formula I are preferably selected from the compounds of formulae I-1 to I-4,

[0093]

[0094] wherein

[0095] alkyl and alkyl’, independently of one another, represent an alkyl group having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0096] alkoxy represents an alkoxy group having 1 to 5 C atoms, preferably having 2 to 4 C atoms,

[0097] alkenyl represents an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms, and

[0098] alkenyl’ represents an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms.

[0099] In an embodiment, the medium according to the invention comprises one or more compounds of formula I (selected from the compounds of formulae I-1 to I-4) together with one or more compounds selected from the compounds of formulae IA-1 to IA-18:

[0100]

[0101]

[0102]

[0103] wherein alkyl represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

[0104] Preferably, the medium comprises one or more compounds of formula I-1, preferably selected from the compounds of formulae I-1-1 to I-1-6

[0105]

[0106] Preferably, the medium according to the invention comprises one or more compounds of formula I-2-1 and / or I-2-2

[0107]

[0108] Preferably, the medium according to the invention comprises a compound of formula I-3, especially selected from the compounds of formulae I-3-1 to I-3-5

[0109]

[0110] Preferably, the medium according to the invention comprises a compound of formula I-4, especially selected from the compounds of formulae I-4-1 and I-4-2

[0111]

[0112] In the compounds of formulae IIA, IIB and IID, Z 2 may have the same or different meanings. In the compounds of formula IIB, Z 2 and Z 2B may have the same or different meanings. In the compounds of formula IID, Z 2 and Z 2D may have the same or different meanings.

[0113] In the compounds of formulae IIA, IIB, IIC and IID, R 2A , R 2B , R 2C and R 2D each preferably represents an alkyl group having 1 to 6 C atoms, especially CH3, C2H5, n-C3H7, n-C4H9, n-C5H 11 .

[0114] In the compounds of formulae IIA, IIB and IID, L 1 , L 2 , L 3 and L 4 preferably represent L 1 =L 2 =F and L 3 =L 4 =F, in addition L 1 =F and L2 = Cl, L 1 = Cl and L 2 = F, L 3 = F and L 4 = Cl, L 3 = Cl and L 4 = F and Y = H. Z in Formulas IIA and IIB 2 and Z 2B each preferably independently represents a single bond, in addition -C2H4-bridge.

[0115] If in Formula IIB, Z 2 = -C2H4- or -CH2O-, Z 2B is preferably a single bond, or if Z 2B = -C2H4- or -CH2O-, Z 2 is preferably a single bond.

[0116] In Formula IID, Z 2D is preferably a single bond or -CH2O-.

[0117] In the compounds of Formulas IIA, IIB and IID, (O)C v H 2v+1 preferably represents OC v H 2v+1 . In the compounds of Formula IIC, (O)C v H 2v+1 preferably represents C v H 2v+1 .

[0118] In the compounds of Formula IIC, L 3 and L 4 each preferably represents F.

[0119] Preferred compounds of Formulas IIA, IIB, IIC and IID are indicated below:

[0120]

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130] wherein the parameter a represents 1 or 2, alkyl and alkyl* each independently of one another represent straight-chain alkyls having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl 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-.

[0131] Particularly preferred mixtures according to the invention comprise one or more compounds of the formulas IIA-2, IIA-8, IIA-10, IIA-16, IIA-18, IIA-40, IIA-41, IIA-42, IIA-43, IIB-2, IIB-10, IIB-16, IIC-1, IID-4 and IID-10.

[0132] The proportion of the compounds of the formulas IIA and / or IIB in the mixture as a whole is preferably at least 20% by weight.

[0133] Preferred media according to the invention comprise at least one compound of the formula IIC-1,

[0134]

[0135] wherein alkyl and alkyl* have the abovementioned meanings, in a preferred amount of <5% by weight, in particular >3% by weight.

[0136] In particular, the medium comprises one or more compounds of the formula IIA-2 selected from the following sub-formulas:

[0137]

[0138] Alternatively, preferably, in addition to the compounds of the formulas IIA-2-1 to IIA-2-5, the medium further comprises one or more compounds of the formulas IIA-2a-1 to IIA-2a-5:

[0139]

[0140] In particular, the medium comprises one or more compounds of the formula IIA-10 selected from the following sub-formulas:

[0141]

[0142]

[0143] Alternatively, preferably, in addition to the compounds of formulas IIA-10-1 to IIA-10-5, the medium further comprises one or more compounds of formulas IIA-10a-1 to IIA-10a-5:

[0144]

[0145] In particular, the medium comprises one or more compounds of formula IIB-10 selected from the following sub-formulas:

[0146]

[0147] Alternatively, preferably, in addition to the compounds of formulas IIB-10-1 to IIB-10-5, the medium further comprises one or more compounds of formulas IIB-10a-1 to IIB-10a-5:

[0148]

[0149]

[0150] The medium according to the invention optionally comprises one or more compounds of formula III

[0151]

[0152] wherein

[0153] R 11 and R 12 each independently of one another represent H, an alkyl or alkoxy group having 1 to 15 C atoms, where one or more CH2 groups in these groups may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to one another, and where one or more H atoms may be replaced by halogen,

[0154] A 1 each independently of one another in each occurrence represents

[0155] a) 1,4-cyclohexenylene or 1,4-cyclohexylene, where one or two non-adjacent CH2 groups may be replaced by -O- or -S-,

[0156] b) 1,4-phenylene, where one or two CH groups may be replaced by N, or

[0157] c) a group selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl,

[0158] wherein the groups a), b) and c) may be mono- or poly-substituted by halogen atoms,

[0159] n represents 0, 1 or 2, preferably 0 or 1,

[0160] Z 1 each independently represents, each time it appears, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, and

[0161] L 11 and L 12 each independently represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and

[0162] W represents O or S.

[0163] The compounds of formula III are preferably selected from the compounds of formula III-1 and / or III-2

[0164]

[0165] wherein the groups appearing have the same meanings as given under formula III above and preferably

[0166] R 11 and R 12 each independently is an alkyl, alkenyl or alkoxy group having at most 15 carbon atoms, more preferably one or both of them represent an alkoxy group, and

[0167] L 11 and L 12 each preferably represents F.

[0168] Preferably, the compounds of formula III-1 are selected from the group of compounds of formula III-1-1 to III-1-11, preferably the compound of formula III-1-6,

[0169]

[0170]

[0171] wherein

[0172] alkyl and alkyl* each independently of the other represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl* each independently of the other represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy* each independently of the other represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 11 and L 12 each independently of the other represent F or Cl, preferably both are F.

[0173] Preferably, the compounds of formula III-2 are selected from the group of compounds of formulae III-2-1 to III-2-10, preferably the compound of formula III-2-6,

[0174]

[0175]

[0176] wherein

[0177] alkyl and alkyl* each independently of the other represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl* each independently of the other represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy* each independently of the other represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 1 and L 2 each independently of the other represent F or Cl, preferably both are F.

[0178] Optionally, the medium contains one or more compounds of formulae IIIA-1 and / or IIIA-2

[0179]

[0180] wherein L 11 and L 12 have the same meanings as given under formula III, (O) represents O or a single bond,

[0181] R IIIA represents an alkyl or alkenyl group having at most 7 C atoms or the group Cy-C m H 2m+1 -,

[0182] m and n are the same or different and are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1,

[0183] Cy represents an alicyclic group having 3, 4 or 5 ring atoms, which is optionally substituted by an alkyl or alkenyl each having at most 3 C atoms, or by halogen or CN, and preferably represents cyclopropyl, cyclobutyl or cyclopentyl.

[0184] The compounds of formulae IIIA-1 and / or IIIA-2 are included in the medium, as an alternative or supplement to the compounds of formula III, preferably as a supplement thereto.

[0185] Very preferred compounds of formulae IIIA-1 and IIIA-2 are the following:

[0186]

[0187]

[0188] where alkoxy represents a straight-chain alkoxy having 1-6 C atoms or alternatively –(CH2) n F, where n is 2, 3, 4, or 5, preferably C2H4F.

[0189] In a preferred embodiment of the invention, the medium comprises one or more compounds of formula III-3

[0190]

[0191] where

[0192] R 11 , R 12 are the same or different and represent H, an alkyl or alkoxy having 1 to 15 C atoms, where in these groups one or more CH2 groups are optionally replaced, independently of one another, by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly linked to one another, and where, furthermore, one or more H atoms may be replaced by halogen.

[0193] The compounds of formula III-3 are preferably selected from the group of compounds of formulae III-3-1 to III-3-10:

[0194]

[0195]

[0196] where R 12 represents an alkyl having 1-7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl or alternatively –(CH2) n F, where n is 2, 3, 4, or 5, preferably C2H4F.

[0197] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formulae III-4 to III-6, preferably a compound of formula III-5,

[0198]

[0199] wherein the parameters have the meanings given above, R 11 preferably represents a straight-chain alkyl and R 12 preferably represents an alkoxy group, each having 1-7 C atoms.

[0200] In a preferred embodiment, the medium comprises one or more compounds of formula I, which are selected from the group of compounds of formulae III-7 to III-9, preferably a compound of formula III-8,

[0201]

[0202]

[0203] wherein the parameters have the meanings given above, R 11 preferably represents a straight-chain alkyl and R 12 preferably represents an alkoxy group each having 1-7 C atoms.

[0204] Preferred compounds of formula IVa are selected from the compounds of formulae IVa-1 to IVa-4:

[0205]

[0206] wherein

[0207] alkyl and

[0208] alkyl* each independently of the other represents a straight-chain alkyl having 1 to 6 C atoms.

[0209] The medium according to the invention preferably comprises at least one compound of formula IVa-2.

[0210] Preferred compounds of formula IVb are selected from the compounds of formulae IVb-1 to IVb-3:

[0211]

[0212] wherein

[0213] alkyl and alkyl* each independently of the other represents a straight-chain alkyl having 1 to 6 C atoms, and

[0214] alkenyl and alkenyl* each independently of the other represents a straight-chain alkenyl having 2 to 6 C atoms.

[0215] Among the compounds of formulae IVb-1 to IVb-3, the compound of formula IVb-1 is particularly preferred.

[0216] Particularly preferred compounds of formula IVb are selected from the following compounds:

[0217]

[0218] The medium according to the invention particularly preferably comprises the compound IVb-1-1.

[0219] The compounds of formula V are preferably selected from the compounds of formulae V-1 to V-16:

[0220]

[0221]

[0222] wherein R 1 and R 2 have the meanings given for R above 2A above.

[0223] R 1 and R 2 each preferably independently of one another represent a straight-chain alkyl group having 1 to 7 C atoms or an alkenyl group having 2 to 7 C atoms.

[0224] Preferred media comprise one or more compounds of formulae V-1, V-3, V-4, V-6, V-7, V-10, V-11, V-12, V-14, V-15 and / or V-16. Very preferably, the medium comprises one or more compounds of formula V-16.

[0225] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of formulae VI-1 to VI-9

[0226]

[0227]

[0228] wherein

[0229] R 7 each independently of one another has one of the meanings given for R in claim 5, and 2A and

[0230] w and x each independently of one another represent 1 to 6.

[0231] Particularly preferably, a mixture comprising at least one compound of formula V-9 is included.

[0232] In a preferred embodiment of the present invention, the medium additionally comprises one or more compounds of formulae VII-1 to VII-21,

[0233]

[0234]

[0235]

[0236] wherein

[0237] R represents a straight-chain alkyl or alkoxy group having 1-6 C atoms, (O) represents -O- or a single bond, and m is 0, 1, 2, 3, 4, 5 or 6 and n is 0, 1, 2, 3 or 4.

[0238] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0239] Particularly preferred are the compounds of formulae VII-1, VII-2, VII-4, VII-20 and VII-21. In these compounds, R preferably represents an alkyl group as well as an alkoxy group, each having 1-5 C atoms. In the compound of formula VII-20, R preferably represents an alkyl or alkenyl group, especially an alkyl group. In the compound of formula VII-21, R preferably represents an alkyl group.

[0240] The total concentration of the compound of formula I in the medium preferably ranges from 10% to 40%, preferably from 12% to 35%, very preferably from 15% to 30%.

[0241] The total concentration of the compound of formula IVa in the medium preferably ranges from 4% to 20%, preferably from 6% to 18%, very preferably from 8% to 15%.

[0242] The total concentration of the compound of formula IVb in the medium preferably ranges from 2% to 15%, preferably from 3% to 12%, very preferably from 4% to 10%.

[0243] The total concentration of the compound of formula V in the medium preferably ranges from 2% to 15%, preferably from 3% to 12%, very preferably from 4% to 10%.

[0244] The total concentration of the compound of formula IIA in the medium preferably ranges from preferably from 15% to 50%, preferably from 20% to 45%, very preferably from 25% to 40%.

[0245] The total concentration of the compound of formula IIB in the medium preferably ranges from 5% to 30%, preferably from 8% to 25%, very preferably from 10% to 20%.

[0246] In a particularly preferred embodiment of the present invention, the medium comprises a compound of formula I-1-1

[0247] ,

[0248] in a concentration range of 6% to 9%, and

[0249] a compound of formula I-1-5

[0250] ,

[0251] in a concentration range of 6% to 9%, and

[0252] a compound of formula I-1-6

[0253] ,

[0254] in a concentration range of 5% to 8%, and

[0255] a compound of formula IVa-2-1

[0256] ,

[0257] in a concentration range of 10% to 13%, and

[0258] a compound of formula IVb-1-1

[0259] ,

[0260] in a concentration range of 5% to 8%, and

[0261] a compound of formula V-16-1

[0262] ,

[0263] in a concentration range of 5% to 8%, and

[0264] a compound of formula IIA-2-2

[0265] ,

[0266] in a concentration range of 8 to 11%, and

[0267] a compound of formula IIA-2-5

[0268] ,

[0269] in a concentration range of 6 to 9%, and

[0270] a compound of formula IIA-10-2

[0271] ,

[0272] Its concentration ranges from 6% to 9%, and

[0273] the compound of formula IIA-10-4

[0274] ,

[0275] its concentration ranges from 6 to 9%, and

[0276] the compound of formula IIB-10-1

[0277] ,

[0278] its concentration ranges from 7 to 10%, and

[0279] the compound of formula IIB-10-4

[0280] ,

[0281] its concentration ranges from 7 to 10%.

[0282] In context, it goes without saying that the percentages of the individual mixture components do not exceed 100%.

[0283] The medium according to the invention preferably comprises compounds of formula I-1-1, I-1-5, I-1-6, V-16-1, IVa-2-1, IVb-1-1, IIA-2-2, IIA-2-5, IIA-10-2, IIA-10-4, IIB-10-1, IIB-10-4, with a total concentration range of 80% to 100%, more preferably 90% to 99%, very preferably 95% to 98%.

[0284] The medium according to the invention preferably consists of 100% of the compounds of formula I-1-1, I-1-5, I-1-6, V-16-1, IVa-2-1, IVb-1-1, IIA-2-2, IIA-2-5, IIA-10-2, IIA-10-4, IIB-10-1, IIB-10-4.

[0285] The invention further relates to a medium consisting of the above-mentioned medium (also referred to herein as the host medium) and, in addition, a chiral dopant.

[0286] The invention further relates to a medium consisting of the above-mentioned medium (also referred to herein as the host medium) and, in addition, a polymerizable compound.

[0287] The invention further relates to a medium consisting of the above-mentioned medium (also referred to herein as the host medium) and, in addition, a chiral dopant and a polymerizable compound.

[0288] The following lists other preferred embodiments:

[0289] a) A liquid crystal medium comprising at least one compound of formulae Z-1 to Z-7,

[0290]

[0291] wherein R and alkyl have the meanings indicated above for formula III.

[0292] b) A preferred liquid crystal medium according to the invention comprises one or more substances containing a tetrahydronaphthyl or naphthyl unit, such as compounds of formulae N-1 to N-5,

[0293]

[0294] wherein R 1N and R 2N each independently of one another have the meaning indicated for R 2A and preferably represent a straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and

[0295] Z 1 and Z 2 each independently of one another represent -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond.

[0296] c) A preferred mixture comprises one or more compounds selected from the following: difluorodibenzochroman compounds of formula BC, chromans of formula CR and fluorinated phenanthrenes of formulae PH-1 and PH-2,

[0297]

[0298]

[0299] wherein

[0300] R B1 , R B2 , R CR1 , R CR2 , R 1 , R 2 each independently of one another have the meaning of R 2A . c is 0, 1 or 2. R 1 and R 2 preferably, independently of one another, represent an alkyl or alkoxy having 1 to 6 C atoms.

[0301] Particularly preferred compounds of the formulas BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5,

[0302]

[0303]

[0304] wherein

[0305] alkyl and alkyl* each independently of one another denote straight-chain alkyl having 1 to 6 C atoms, and

[0306] alkenyl and

[0307] alkenyl* each independently of one another denote straight-chain alkenyl having 2 to 6 C atoms.

[0308] A very particularly preferred mixture comprises one, two or three compounds of the formulas BC-2, BF-1 and / or BF-2.

[0309] d) Preferred mixtures comprise one or more indane compounds of the formula In,

[0310]

[0311] wherein

[0312] R 11 、R 12 、R 13 each independently of one another denote straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl having 1-6 C atoms,

[0313] R 12 and R 13 additionally denote halogen, preferably F,

[0314]

[0315] i denotes 0, 1 or 2.

[0316] Preferred compounds of the formula In are the compounds of the formulas In-1 to In-16 indicated below:

[0317]

[0318]

[0319] Particularly preferred are the compounds of the formulas In-1, In-2, In-3 and In-4.

[0320] e) The preferred mixture additionally contains one or more compounds of the formulas L-1 to L-5,

[0321]

[0322] wherein

[0323] R, R 1 and R 2 each independently of one another have the meanings indicated above for R 2A in formula IIA, and alkyl represents an alkyl group having 1 to 6 C atoms. The parameter s represents 1 or 2.

[0324] The compounds of the formulas L-1 to L-9 are preferably used in a concentration of 5-15 wt%, in particular 5-12 wt% and very particularly preferably 8-10 wt%.

[0325] f) The preferred mixture additionally contains one or more compounds of the formula IIA-Y

[0326]

[0327] wherein R 11 and R 12 have one of the meanings given above for R 2A in formula IIA, and L 1 and L 2 independently of one another represent F or Cl.

[0328] The preferred compounds of the formula IIA-Y are selected from the following sub-formulas

[0329]

[0330]

[0331] wherein, Alkyl and Alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms, Alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms, Alkenyl and Alkenyl* each independently of one another represent a straight-chain alkenyl group having 2 to 6 C atoms, and O represents an oxygen atom or a single bond. Alkenyl and Alkenyl* preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0332] The particularly preferred compounds of the formula IIA-Y are selected from the following sub-formulas:

[0333]

[0334] wherein Alkoxy and Alkoxy* have the meanings defined above and preferably represent methoxy, ethoxy, n-propoxy, n-butoxy or n-pentyloxy.

[0335] The liquid crystal medium according to the invention (also referred to herein as the liquid crystal host mixture) is suitable for use in polymer-stabilized displays. For this purpose, the medium according to the invention optionally contains one or more polymerizable compounds of the formula P:

[0336] P-Sp-A 1 -(Z 1 -A 2 ) z -R P

[0337] wherein each group is independent of one another and each occurrence, the same or different, has the following meanings:

[0338] P is a polymerizable group,

[0339] Sp is a spacer group or a single bond,

[0340] A 1 、A 2 is an aromatic, heteroaromatic, cycloaliphatic or heterocyclic group, preferably having 4 to 25 ring atoms, which may also contain fused rings, and which is unsubstituted, or mono- or polysubstituted by L,

[0341] Z 1 is -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH2-CH2-CO-O-, -O-CO-CH2-CH2-, -CR 0 R 00 - or a single bond,

[0342] R 0 、R 00 is H or an alkyl group having 1 to 12 C atoms,

[0343] R is H, L or P-Sp-,

[0344] L is F, Cl, -CN, P-Sp-, or a straight-chain, branched-chain or cycloalkyl group having 1 to 25 C atoms, where 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 O and / or S atoms are not directly linked to each other, and where one or more H atoms are each optionally replaced by P-Sp-, F or Cl,

[0345] z is 0, 1, 2 or 3,

[0346] n1 is 1, 2, 3 or 4.

[0347] As used herein, the terms "active layer" and "switchable layer" denote, in an electro-optical display, for example in an LC display, a layer containing one or more molecules having structural and optical anisotropy (such as LC molecules), which molecules change their orientation when subjected to an external stimulus such as an electric or magnetic field, which results in a change in the transmittance of the layer for polarized or non-polarized light.

[0348] As used herein, the terms "tilt" and "tilt angle" are to be understood as denoting a tilted alignment of the LC molecules of an LC medium with respect to the cell surface in an LC display (preferably a PSA display here). The tilt angle here denotes the average angle (<90°) between the longitudinal molecular axis (LC director) of the LC molecules and the outer plate parallel to the plane forming the LC cell. Here, a low value of the tilt angle (i.e., a large deviation from the 90° angle) corresponds to a large tilt. Suitable methods for measuring the tilt angle are given in the examples. Unless otherwise stated, the tilt angle values disclosed in the context relate to this measurement method.

[0349] As used herein, the terms "reactive mesogen" and "RM" are to be understood as denoting a compound containing a mesogenic or liquid-crystalline backbone and one or more functional groups suitable for polymerization attached thereto, and said functional groups are also referred to as "polymerizable groups" or "P".

[0350] Unless otherwise stated, the term "polymerizable compound" as used herein is to be understood as a polymerizable monomeric compound.

[0351] As used herein, the term "low molecular weight compound" is to be understood as denoting monomeric and / or compounds not prepared by a polymerization reaction, as opposed to "polymeric compounds" or "polymers".

[0352] As used herein, the term "non-polymerizable compound" is to be understood as denoting a compound not containing functional groups suitable for polymerization under the conditions normally applied for the polymerization of RM.

[0353] As used herein, the term "mesogenic group" is known to those skilled in the art and has been described in the literature, and it refers to a group that substantially contributes to the formation of a liquid crystal (LC) phase in low molecular weight or polymeric substances due to the anisotropy of its attractive and repulsive interactions. Compounds containing mesogenic groups (mesogenic compounds) do not necessarily have an LC phase per se. Mesogenic compounds can also exhibit LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod-like or disc-like units. Terms and definitions related to 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.

[0354] As used herein, the terms "optically active" and "chiral" are synonyms for a material that can induce a helical pitch in a nematic host material, also referred to as a "chiral dopant".

[0355] As used herein, the term "spacer group" (also referred to hereinafter as "Sp") is known to those skilled in the art in the prior art and has been described in the literature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340 - 6368. As used herein, the term "spacer group" or "spacer" refers to a flexible group, for example, an alkylene group, which is connected to a mesogenic group or a polymerizable group(s) in a polymerizable mesogenic compound.

[0356] In the context, represents a trans - 1,4 - cyclohexylene ring.

[0357] In the group the single bond shown between two ring atoms can be connected to any free position of the benzene ring.

[0358] "Organic group" in the context refers to a carbon or hydrocarbon group.

[0359] "Carbon group" refers to a mono - or polyvalent organic group containing at least one carbon atom, where the group does not contain other atoms (e.g., -C≡C-) or optionally contains one or more other atoms, such as N, O, S, B, P, Si, Se, As, Te, or Ge (e.g., carbonyl, etc.). The term "hydrocarbon group" refers to a carbon group that additionally contains one or more H atoms and optionally one or more heteroatoms, such as N, O, S, B, P, Si, Se, As, Te, or Ge.

[0360] "Halogen" means F, Cl, Br or I, preferably F or Cl.

[0361] -CO-, -C(=O)- and -C(O)- represent a carbonyl group, i.e.

[0362] A carbon or hydrocarbon group may be a saturated or unsaturated group. Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. A carbon or hydrocarbon group having more than 3 C atoms may be straight-chain, branched and / or cyclic and may also contain spiro linkages or fused rings.

[0363] The terms "alkyl", "aryl", "heteroaryl", etc. also include polyvalent groups, such as alkylene, arylene, heteroarylene, etc.

[0364] The term "aryl" means an aromatic carbon group or a group derived therefrom. The term "heteroaryl" means an "aryl" as defined above containing one or more heteroatoms (preferably selected from N, O, S, Se, Te, Si and Ge).

[0365] Preferred carbon and hydrocarbon groups are optionally substituted, straight-chain, branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy having 1 to 40, preferably 1 to 20, very preferably 1 to 12 C atoms, optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to 25 C atoms, or optionally substituted alkylaryl, aralkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to 25 C atoms, wherein one or more C atoms may also be replaced by heteroatoms (preferably selected from N, O, S, Se, Te, Si and Ge).

[0366] Further preferred carbon and hydrocarbon groups are C1-C 20 alkyl, C2-C 20 alkenyl, C2-C 20 alkynyl, C3-C 20 allyl, C4-C 20 alkyldienyl, C4-C 20 polyenyl, C6-C 20 cycloalkyl, C4-C 15 cycloalkenyl, C6-C 30 aryl, C6-C 30 alkylaryl, C6-C 30 aralkyl, C6-C 30 alkylaryloxy, C6-C 30 arylalkyloxy, C2-C 30 heteroaryl, C2-C 30 heteroaryloxy.

[0367] Particularly preferred are C1-C 12 alkyl, C2-C 12 alkenyl, C2-C 12 alkynyl, C6-C 25 aryl and C2-C 25 heteroaryl.

[0368] Further preferred carbon-based and hydrocarbon groups are straight-chain, branched-chain or cyclic alkyl groups having 1-20, preferably 1-12 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 can each independently of one another be replaced by -C(R x )=C(R x )-, -C≡-, -N(R x )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another.

[0369] R x preferably represents H, F, Cl, CN, a straight-chain, branched-chain or cyclic alkyl chain having 1 to 25 C atoms, in which additionally one or more non-adjacent C atoms can be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, and in which one or more H atoms can be replaced by F or Cl, or represents an optionally substituted aryl or aryloxy group having 6 to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 30 C atoms.

[0370] 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, dodecyl, trifluoromethyl, perfluorobutyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.

[0371] Preferred alkenyl groups are, for example, vinyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, etc.

[0372] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl, etc.

[0373] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, 2-methylbutoxy, n-pentyloxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, etc.

[0374] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, etc.

[0375] Aryl and heteroaryl groups can be monocyclic or polycyclic, i.e., they can contain one ring (e.g., phenyl) or two or more rings, which can also be fused (e.g., naphthyl) or covalently bonded (e.g., biphenyl), or contain a combination of fused and linked rings. Heteroaryl contains one or more heteroatoms, preferably selected from O, N, S, and Se.

[0376] Particularly preferred are mono-, bi- or tricyclic aryls having 6 - 25 C atoms and mono-, bi- or tricyclic heteroaryls having 5 - 25 ring atoms, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6- or 7-membered aryl and heteroaryl groups, wherein additionally, one or more CH groups can be replaced by N, S or O in such a way that O atoms and / or S atoms are not directly connected to each other.

[0377] Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1,1':3',1”]-terphenyl-2'-yl, naphthyl, anthracenyl, binaphthyl, phenanthrenyl, 9,10-dihydro-phenanthrenyl, pyrene, dihydropyrene, picene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, etc.

[0378] Preferred heteroaryl groups are, for example, 5-membered rings such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine or fused groups such as indole, isoindole, indene, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthrimidazole, pyridinimidazole, pyrazinimidazole, quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarbazole, phenanthridine, phenanthroline, thiophene[2,3b]thiophene, thiophene[3,2b]thiophene, dithiophenothiophene, isobenzothiophene, dibenzothiophene, benzothiophene, benzothiadiazolethiophene, or combinations of these groups.

[0379] The aryl and heteroaryl groups mentioned in the context may also be substituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or other aryl or heteroaryl groups.

[0380] (Non-aromatic) alicyclic groups and heterocyclic groups include both saturated rings, i.e., rings containing only single bonds, and partially unsaturated rings, i.e., those that may also contain multiple bonds. The heterocycle contains one or more heteroatoms, preferably selected from Si, O, N, S, and Se.

[0381] (Non-aromatic) alicyclic groups and heterocyclic groups may be monocyclic, i.e., containing only one ring (e.g., cyclohexane), or polycyclic, i.e., containing multiple rings (e.g., decalin or bicyclooctane). Saturated groups are particularly preferred. Also preferred are mono-, bi- or tricyclic groups having 5-25 ring atoms, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6-, 7- or 8-membered carbocyclic groups, wherein, additionally, 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-.

[0382] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups such as cyclopentane, tetrahydrofuran, tetrahydrothiophene, pyrrolidine; 6-membered groups such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine; 7-membered groups such as cycloheptane; and fused groups such as 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-methanoindane-2,5-diyl.

[0383] Preferred substituents are, for example, solubility enhancing groups such as alkyl or alkoxy; electron-withdrawing groups such as fluorine, nitro or nitrile; or substituents for increasing the glass transition temperature (Tg) of the polymer, in particular bulky groups such as tert-butyl or optionally substituted aryl.

[0384] Preferred substituents, also referred to hereinafter as “L S ”, are, for example, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1-25 C atoms, where one or more H atoms may optionally be replaced by F or Cl, optionally substituted silyl having 1 to 20 Si atoms, or optionally substituted aryl having 6 to 25, preferably 6 to 15 C atoms.

[0385] where R x represents H, F, Cl, CN, or straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, where 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 O- and / or S-atoms are not directly linked to one another, and where one or more H atoms are each optionally replaced by F, Cl, P- or P-Sp-, and

[0386] Y 1 represents halogen.

[0387] “Substituted silyl or aryl” preferably means that it is substituted by halogen, -CN, R 0 , -OR 0 , -CO-R 0 , -CO-O-R 0、 -O-CO-R 0 or -O-CO-O-R 0 is substituted, where R 0 represents H or an alkyl group having 1 to 20 C atoms.

[0388] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and in addition phenyl.

[0389] A 1 and A 2 very preferably represents wherein L has one of the above meanings and r represents 0, 1, 2, 3 or 4, in particular

[0390] represents

[0391] The polymerizable group P is a group suitable for polymerization reactions (such as free radical or ionic chain polymerization, addition polymerization or condensation polymerization), or a group suitable for polymer-analogous reactions (such as addition or condensation on the polymer backbone). Particularly preferred are groups for chain polymerization, especially those containing a C═C double bond or a -C≡C- triple bond, and groups suitable for ring-opening polymerization, such as oxetanyl or epoxy groups.

[0392] Preferred groups P are selected from the group consisting of: 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 W3 -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 an alkyl group having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 each independently of one another 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 different from P-SP- as defined above, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0393] Very preferred groups P are selected from the group consisting of: CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -O-, CH2=CW 2 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O)k2 - 1. Phe-CH=CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or an alkyl group having 1 to 5 C atoms, especially H, F, Cl or CH3, and W 2 and W 3 each independently of one another represents H or an alkyl group having 1 to 5 C atoms, especially H, methyl, ethyl or n-propyl, and W 4 、W 5 and W 6 each independently of one another represents Cl, an oxaalkyl group or an oxacarbonylalkyl group having 1 to 5 C atoms, and W 7 and W 8 each independently of one another represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0394] Very preferred groups P are selected from the group consisting of: CH2=CW 1 -CO-O-, especially CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, and also CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-,

[0395] Other particularly preferred polymerizable groups P are selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl and epoxy groups, and most preferably from acrylate and methacrylate groups.

[0396] If the spacer group Sp is different from a single bond, it is preferably of the formula Sp"-X" such that the individual groups P-Sp- correspond to the formula R-Sp"-X"-, where

[0397] Sp" represents a straight-chain or branched alkylene group having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein furthermore, one or more non-adjacent CH2 groups are each independently of one another replaced by -O-, -S-, -NH-, -N(R 0 )-, -Si(R 0 R 00 )-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N(R 00)-CO-O-, -O-CO-N(R 0 )-, -N(R 0 )-CO-N(R 00 )-, -CH=CH- or -C≡C- are replaced in such a way that O and / or S atoms are not directly connected to each other,

[0398] X" represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 )-, -N(R 0 )-CO-, -N(R 0 )-CO-N(R 00 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -, -CY 2 =CY 3 -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond,

[0399] R 0 and R 00 each independently of one another represent H or an alkyl group having 1 - 20 C atoms, and

[0400] Y 2 and Y 3 each independently of one another represent H, F, Cl or CN.

[0401] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 00 - or a single bond.

[0402] Typical spacer groups Sp and -Sp"-X"- are for example -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, -(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR0 R 00 -O) p1 -, where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 0 and R 00 have the meanings indicated above.

[0403] Particularly preferred groups Sp and -Sp"-X"- are -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, where p1 and q1 have the meanings indicated above.

[0404] Particularly preferred groups Sp" are, in each case, straight-chain ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethyl-N-methylimino-ethylene, 1-methylalkylene, vinyl, propenyl and butenyl.

[0405] In a preferred embodiment of the present invention, the compounds of formula P and its sub-formulas contain a spacer group Sp substituted by one or more polymerizable groups P, such that the group Sp-P corresponds to Sp(P) s , s being ≥2 (branched polymerizable groups).

[0406] Preferred compounds of formula P according to this preferred embodiment are those in which s is 2, i.e., compounds containing the group Sp(P)2. Very preferred compounds of formula P according to this preferred embodiment contain a group selected from the following formulas:

[0407] -X-alkyl-CHPP S1

[0408] -X-alkyl-CH((CH2) aa P)((CH2) bb P) S2

[0409] -X-N((CH2) aa P)((CH2) bb P) S3

[0410] -X-alkyl-CHP-CH2-CH2P S4

[0411] -X-alkyl-C(CH2P)(CH2P)-C aa H 2aa+1S5

[0412] -X-alkyl-CHP-CH2P S6

[0413] -X-alkyl-CPP-C aa H 2aa+1 S7

[0414] -X-alkyl-CHPCHP-C aa H 2aa+1 S8

[0415] wherein P is as defined in formula P,

[0416] alkyl represents a single bond or a straight-chain or branched-chain alkylene having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN, and one or more non-adjacent CH2 groups may each independently of one another be replaced by -C(R 0 )=C(R 0 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- such that the O atoms and / or S atoms are not directly linked to one another, where R 0 has the meaning indicated above,

[0417] aa and bb each independently of one another represent 0, 1, 2, 3, 4, 5 or 6,

[0418] X has one of the meanings indicated for X", and is preferably O, CO, SO2, O-CO-, CO-O or a single bond.

[0419] Preferred spacer groups Sp(P)2 are selected from formulae S1, S2 and S3.

[0420] Very preferred spacer groups Sp(P)2 are selected from the following sub-formulae:

[0421] -CHPP S1a

[0422] -O-CHPP S1b

[0423] -CH2-CHPP S1c

[0424] -OCH2-CHPP S1d

[0425] -CH(CH2-P)(CH2-P) S2a

[0426] -OCH(CH2-P)(CH2-P) S2b

[0427] -CH2-CH(CH2-P)(CH2-P) S2c

[0428] -OCH2-CH(CH2-P)(CH2-P) S2d

[0429] -CO-NH((CH2)2P)((CH2)2P) S3a

[0430] In the compounds of formula P and its sub-formulas as described above and below, P is preferably selected from the group consisting of: vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, and most preferably selected from acrylate and methacrylate.

[0431] More preferably, the compounds are those of formula P and its sub-formulas as described above and below, in which all polymerizable groups P present in the compound have the same meaning, and very preferably represent acrylate or methacrylate, and most preferably methacrylate.

[0432] In the compounds of formula P and its sub-formulas as described above and below, R preferably represents P-Sp-.

[0433] More preferably, the compounds are those of formula P and its sub-formulas as described above and below, where Sp represents a single bond or -(CH2) p1 -、-O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , where p1 is 2, 3, 4, 5 or 6, and if Sp is -O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , then the O-atom or the CO-group is attached to the benzene ring, respectively.

[0434] More preferably, the compounds are those of formula P and its sub-formulas as described above and below, in which at least one group Sp is a single bond.

[0435] More preferably, the compounds are those of formula P and its sub-formulas as described above and below, in which at least one group Sp is different from a single bond, and is preferably selected from -(CH2) p1 -、-O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , where p1 is 2, 3, 4, 5 or 6, and if Sp is -O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2)p1 Then the O-atom or the CO-group is respectively linked to the benzene ring.

[0436] The very preferred group -A in formula P 1 -(Z-A 2 ) z - is selected from the following formulas

[0437]

[0438]

[0439] wherein at least one benzene ring is substituted by at least one group L and the benzene ring is optionally further substituted by one or more groups L or P-Sp-.

[0440] The preferred compounds of formula P and its sub-formulas are selected from the following preferred embodiments, including any combination thereof:

[0441] - all groups P in the compound have the same meaning,

[0442] --A 1 -(Z-A 2 ) z - is selected from formula A1, A2 and A5,

[0443] - the compound contains exactly two polymerizable groups (represented by the group P),

[0444] - the compound contains exactly three polymerizable groups (represented by the group P),

[0445] - P is selected from the group consisting of acrylate, methacrylate and oxetane, very preferably acrylate or methacrylate,

[0446] - P is methacrylate,

[0447] - all groups Sp are single bonds,

[0448] - at least one of the groups Sp is a single bond and at least one of the groups Sp is different from a single bond,

[0449] - When Sp is different from a single bond, it is -(CH2) p2 -、-(CH2) p2 -O-、-(CH2) p2 -CO-O-、-(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or the CO-group is respectively linked to the benzene ring,

[0450] - Sp is a single bond or represents -(CH2) p2 -、-(CH2)p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or CO- group is attached to the benzene ring respectively,

[0451] -R represents P-Sp-,

[0452] -R does not represent or contain a polymerizable group,

[0453] -R does not represent or contain a polymerizable group and represents a straight-chain, branched-chain 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 each other, and wherein one or more H atoms are each optionally replaced by F, Cl or L a substituted,

[0454] -L or L’ represents F, Cl or CN,

[0455] -L is F.

[0456] Suitable and preferred P compounds of the formula are selected from the following formulas:

[0457]

[0458]

[0459]

[0460]

[0461] wherein each group has the following meanings:

[0462] P 1 、P 2 and P 3 each independently of one another represents an acrylate group or a methacrylate group,

[0463] Sp 1 、Sp 2 and Sp 3 each independently of one another represents a single bond or a spacer group (having one of the meanings as described for Sp in the context), and particularly preferably represents -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO- or -(CH2) p1-O-CO-O-, where p1 is an integer from 1 to 12, and in addition, the group P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - one or more of which may represent R aa , provided that the group P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - at least one of which is different from R aa ,

[0464] R aa represents H, F, Cl, CN or a straight-chain or branched alkyl group having 1 to 25 C atoms, wherein one or more additional non-adjacent CH2 groups may also be independently replaced by C(R 0 )=C(R 00 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly connected to each other, and wherein one or more additional H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 -, particularly preferably a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms (wherein the alkenyl and alkynyl groups have at least two C atoms and the branched groups have at least three C atoms),

[0465] R 0 , R 00 each independently of one another and each time they occur, the same or different, represent H or an alkyl group having 1 to 12 C atoms,

[0466] R y and R z each independently of one another represent H, F, CH3 or CF3,

[0467] X 1 、X 2 and X 3 each independently of one another represent -CO-O-, -O-CO- or a single bond,

[0468] Z 1 represents -O-, -CO-, -C(R y R z)- or -CF2CF2-,

[0469] Z 2 and Z 3 each independently of one another represents -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3 or 4,

[0470] L, each time it occurs, is the same or different and represents F, Cl, CN or a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 12 C atoms, preferably F,

[0471] L' and L” each independently of one another represent H, F or Cl,

[0472] k represents 0 or 1,

[0473] r represents 0, 1, 2, 3 or 4,

[0474] s represents 0, 1, 2 or 3,

[0475] t represents 0, 1 or 2,

[0476] x represents 0 or 1.

[0477] Particularly preferred are the compounds of the formulas P2, P13, P17, P22, P23, P24, P30, P31 and P32.

[0478] More preferred are the tri-reactive compounds P15 to P30, especially P17, P18, P19, P22, P23, P24, P25, P26, P30, P31 and P32.

[0479] In the compounds of P1 to P32, the group

[0480] is preferably

[0481] wherein L, each time it occurs, is the same or different and has one of the meanings given above or below, and is preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, OCH3, COCH3 or OCF3, especially F or CH3.

[0482] The medium according to the invention comprises one or more chiral dopants. Preferably, the absolute value of the helical twisting power (HTP) of these chiral dopants is in the range of 1 μm -1 to 150 μm -1 and preferably in the range of 10 μm -1 to 100 μm -1 In the case where the medium comprises two or more chiral dopants, these may have opposite signs of their HTP values. For some specific embodiments, this condition is preferred because it allows compensation of the chirality of the corresponding compounds to a certain extent and can thus be used to compensate for various temperature-dependent properties of the resulting medium in a device. However, generally, it is preferred that most, preferably all, of the chiral compounds present in the medium according to the invention have the same sign of their HTP values.

[0483] Preferably, the chiral dopants present in the medium according to the present application are mesogenic compounds and most preferably they themselves exhibit a mesophase.

[0484] In a preferred embodiment of the invention, the medium comprises two or more chiral compounds all having the same algebraic sign of HTP.

[0485] The temperature dependence of the HTP of each compound can be high or low. The temperature dependence of the pitch of the medium can be compensated by mixing compounds having different temperature dependences of HTP in the corresponding ratios.

[0486] For the optically active components, a variety of chiral dopants are available to those skilled in the art, some of which are commercially available, for example, cholesteryl nonanoate, R- and S-811, R- and S-1011, R- and S-2011, R- and S-3011, R- and S-4011 or CB15 (all from Merck KGaA, Darmstadt).

[0487] Particularly suitable dopants are compounds containing one or more chiral groups and one or more mesogenic groups, or one or more aromatic or cycloaliphatic groups which form mesogenic groups with chiral groups.

[0488] Suitable chiral groups are, for example, chiral branched hydrocarbon groups, chiral ethylene glycols, binaphthols or dioxolanes, and furthermore mono- or polyvalent chiral groups selected from: sugar derivatives, sugar alcohols, sugar acids, lactic acid, chiral substituted diols, steroid derivatives, terpene derivatives, amino acids or sequences of several (preferably 1 to 5) amino acids.

[0489] Preferred chiral groups are sugar derivatives such as glucose, mannose, galactose, fructose, arabinose and dextrose; sugar alcohols such as sorbitol, mannitol, iditol, galactitol or their dehydration derivatives, in particular dianhydrohexitols such as dianhydrosorbitol (1,4:3,6-dianhydro-D-sorbitol, isosorbide), dianhydromannitol (isosorbide) or dianhydroiditol (isoidide), sugar acids such as gluconic acid, gulonic acid and ketogulonic acid, chiral substituted diol groups such as mono- or oligoethylene glycol or propylene glycol in which one or more CH2 groups are replaced by alkyl or alkoxy groups, amino acids such as alanine, valine, phenylglycine or phenylalanine or sequences of 1 to 5 of these amino acids, steroid derivatives such as cholesteryl or cholanic acid groups, terpene derivatives such as menthyl, neomenthyl, campheyl, pineyl, terpineyl, isolongifolyl, fenchyl, carreyl, myrthenyl, nopyl, geraniyl, linaloyl, neryl, citronellyl or dihydrocitronellyl.

[0490] The medium according to the invention preferably contains a chiral dopant selected from the group of known chiral dopants. Suitable chiral groups and mesogenic chiral compounds are described, for example, in DE 34 25 503, DE 35 34 777, DE 35 34 778, DE 35 34779 and DE 35 34 780, DE 43 42 280, EP 01 038 941 and DE 195 41 820. Examples are also the compounds listed in Table F below.

[0491] The chiral compounds preferably used according to the invention are selected from the formulas shown below.

[0492] Particularly preferred chiral dopants are selected from compounds of the following formulas A-I to A-III and A-Ch:

[0493]

[0494] wherein

[0495] R a11 、R a12 and R b12 each independently represents an alkyl group having 1 to 15 C atoms, wherein, in addition, one or more non-adjacent CH2 groups may each independently be replaced by -C(R z )=C(R z )-, -C≡C-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and / or S atoms are not directly linked to each other, and wherein, in addition, one or more H atoms may each be replaced by F, Cl, Br, I or CN, preferably an alkyl group, more preferably a n-alkyl group, provided that R a12 is different from R b12

[0496] R a21 and R a22 each independently represents an alkyl group having 1 to 15 C atoms, wherein, in addition, one or more non-adjacent CH2 groups may each independently be replaced by -C(R z )=C(R z )-, -C≡C-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and / or S atoms are not directly linked to each other, and wherein, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN, preferably both are alkyl groups, more preferably n-alkyl groups,

[0497] R a31 、R a32 and R b32 each independently represents a straight-chain or branched alkyl group having 1 to 15 C atoms, wherein, in addition, one or more non-adjacent CH2 groups may each independently be replaced by -C(R z )=C(R z )-, -C≡C-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that O and / or S atoms are not directly linked to each other, and wherein, in addition, one or more H atoms may be replaced by F, Cl, Br, I or CN,

[0498] preferably an alkyl group, more preferably an n-alkyl group, provided that R a32 is different from R b32

[0499] R z ​​represents H, CH3, F, Cl or CN, preferably H or F,

[0500] R 8 has one of the meanings of R given above, preferably an alkyl group, more preferably a straight-chain alkyl group having 1-15 C atoms, a11

[0501] Z 8 represents -C(O)O-, -CH2O-, -CF2O- or a single bond, preferably -C(O)O-,

[0502] A 11 as defined below for A 12 or alternatively represents

[0503]

[0504] A 12 represents

[0505]

[0506] preferably

[0507]

[0508]

[0509] wherein

[0510] L 12 each independently represents halogen, CN or an alkyl, alkenyl, alkoxy or alkenyloxy group having at most 12 C atoms and one or more H atoms optionally replaced by halogen, preferably methyl, ethyl, Cl or F, particularly preferably F,

[0511] A 21 represents

[0512]

[0513] A 22 has the meaning given for A 12

[0514] A 31 has the meaning given for A 11 or alternatively represents

[0515]

[0516] A 32 has the meaning given for A 12

[0517] ​​​n2 is, each time it appears, independently of one another, 0, 1 or 2, and

[0518] n3 is 1, 2 or 3, and

[0519] r is 0, 1, 2, 3 or 4.

[0520] Particularly preferred are dopants selected from the group consisting of compounds of the formula:

[0521]

[0522]

[0523] wherein

[0524] m is, each time it appears, independently of one another, an integer from 1 to 9 and

[0525] n is, each time it appears, independently of one another, an integer from 2 to 9.

[0526] Particularly preferred compounds of formula A are compounds of formula A-III.

[0527] Further preferred dopants are derivatives of isosorbide, isomannide or isoidide of formula A-IV:

[0528]

[0529] wherein the group is

[0530] (dianhydro sorbitol),

[0531] (dianhydro mannitol), or

[0532] (dianhydro iditol),

[0533] preferably dianhydro sorbitol,

[0534] and chiral glycols, such as, diphenyl glycol (hydrobenzoin), in particular mesogenic hydrobenzoin derivatives of formula A-V:

[0535]

[0536] including the (S,S) enantiomer not shown,

[0537] wherein

[0538] each are independently of one another 1,4-phenylene (which may also be mono-, di- or tri-substituted by L) or 1,4-cyclohexylene,

[0539] L is H, F, Cl, CN or an alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkoxycarbonyloxy group having 1 to 7 carbon atoms, optionally halogenated,

[0540] c is 0 or 1,

[0541] X is CH2 or -C(O)-,

[0542] Z 0 is -COO-, -OCO-, -CH2CH2- or a single bond, and

[0543] R 0 is an alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy group having 1 - 12 carbon atoms.

[0544] Examples of the compounds of formula IV are:

[0545]

[0546]

[0547] The compounds of formula A-IV are described in WO 98 / 00428. The compounds of formula A-V are described in GB-A-2,328,207.

[0548] Very particularly preferred dopants are chiral binaphthyl derivatives as described in WO 02 / 94805, chiral binaphthol acetal derivatives as described in WO 02 / 34739, chiral TADDOL derivatives as described in WO 02 / 06265 and chiral dopants having at least one fluorinated bridging group and terminal or central chiral groups as described in WO 02 / 06196 and WO 02 / 06195.

[0549] Particularly preferred are chiral compounds of formula A-VI

[0550]

[0551] wherein

[0552] X 1 、X 2 、Y 1 and Y 2 each independently of one another is F, Cl, Br, I, CN, SCN, SF5, a straight-chain or branched alkyl group having 1 - 25 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN and in which, furthermore, one or more non-adjacent CH2 groups may each independently of one another be replaced by -O-, -S-, -NH-, NR x-CO-, -COO-, -OCO-, -OCOO-, -S-CO-, -CO-S-, -CH=CH- or -C≡C- are replaced in such a way that the O and / or S atoms are not directly bonded to each other by a polymerizable group or cycloalkyl or aryl having at most 20 C atoms, which may optionally be monosubstituted or polysubstituted by halogen, preferably F, or by a polymerizable group,

[0553] x 1 and x 2 each independently of one another is 0, 1 or 2,

[0554] y 1 and y 2 each independently of one another is 0, 1, 2, 3 or 4,

[0555] B 1 and B 2 each independently of one another is an aromatic or partially or fully saturated aliphatic six-membered ring, in which one or more CH groups may each be replaced by N and one or more non-adjacent CH2 groups may each be replaced by O or S,

[0556] W 1 and W 2 each independently of one another is -Z 1 -A 1 -(Z 2 -A 2 ) m -R, and one of the two is alternatively R 1 or A 3 , but the two are not simultaneously H, or

[0557] is

[0558] or

[0559]

[0560] U 1 and U 2 each independently of one another is CH2, O, S, CO or CS,

[0561] V 1 and V 2 each independently of one another is (CH2) n , in which one to four non-adjacent CH2 groups may each be replaced by O or S, and V 1 and V 2 one of

[0562] is

[0563] Both are single bonds,

[0564] n is 1, 2 or 3

[0565] Z 1 and Z 2 each independently of one another is -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR x -, -NR x -, -CO-, -O-CH2-, -CH2-O-, -S-CH2-, -CH2-S-, -CF2-O-, -O-CF2-, -CF2-S-, -S-CF2-, -CH2-CH2-, -CF2-CH2-, -CH2-CF2-, -CF2-CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C≡C-, a combination of two of these groups, where no two O and / or S and / or N atoms are directly bonded to one another, preferably -CH=CH-COO- or -COO-CH=CH- or a single bond,

[0566] R x represents an alkyl group having 1 to 6 C atoms,

[0567] A 1 、A 2 and A 3 each independently of one another is 1,4-phenylene, where one or two non-adjacent CH groups can each be replaced by N; 1,4-cyclohexylene, where one or two non-adjacent CH2 groups can each be replaced by O or S; 1,3-dioxolane-4,5-diyl, 1,4-cyclohexenylene, 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, where each of these groups can be mono- or polysubstituted by L, and additionally A 1 can be a single bond,

[0568] L is a halogen atom, preferably F, CN, NO2, an alkyl group, an alkoxy group, an alkylcarbonyl group, an alkoxycarbonyl group or an alkoxycarbonyloxy group having 1 - 7 carbon atoms, where one or more H atoms can each be replaced by F or Cl,

[0569] m is independently 0, 1, 2 or 3 in each case, and

[0570] R and R 1Each is independently of the others H, F, Cl, Br, I, CN, SCN, SF5, a straight-chain or branched alkyl group having 1 or 3 to 25 carbon atoms, which may optionally be mono- or polysubstituted by F, Cl, Br, I or CN, and in which one or more non-adjacent CH2 groups may each be replaced by -O-, -S-, -NH-, -NR 0 -, -CO-, -COO-, -OCO-, -O-COO-, -S-CO-, -CO-S-, -CH=CH- or -C≡C-, where no two O and / or S atoms are directly bonded to one another; or a polymerizable group.

[0571] Particularly preferred are the chiral binaphthyl derivatives of formula A-VI-1

[0572]

[0573] wherein ring B, R 0 and Z 0 are as defined for formulae A-IV and A-V, and b is 0, 1, or 2,

[0574] especially those selected from formulae A-VI-1a to A-VI-1c below:

[0575]

[0576]

[0577] wherein ring B, R 0， and Z 0 are as defined for formula A-VI-1, and

[0578] R 0 is as defined for formula A-IV, or H or an alkyl group having 1-4 carbon atoms, and

[0579] b is 0, 1 or 2,

[0580] and Z 0 is especially -OC(O)- or a single bond.

[0581] The concentration of one or more chiral dopants in the LC medium is preferably from 0.001% to 20%, preferably from 0.05% to 5%, more preferably from 0.1% to 2%, and most preferably from 0.5% to 1.5%. These preferred concentration ranges are particularly applicable to the chiral dopants S-4011 or R-4011 (both from Merck KGaA) and chiral dopants having the same or a similar HTP. For chiral dopants having a higher or lower absolute value of HTP compared to S-4011, these preferred concentrations must be reduced proportionally, or increased proportionally, depending on their HTP value relative to S-4011.

[0582] According to the invention, the pitch p of the LC medium or host mixture is preferably 5 - 50 μm, more preferably 8 - 30 μm and particularly preferably 10 - 20 μm.

[0583] Preferably, the medium according to the invention comprises a stabilizer selected from the compounds of formulae ST-1 to ST-19.

[0584]

[0585]

[0586]

[0587]

[0588] wherein

[0589] R ST represents H, an alkyl or alkoxy group having 1 - 15 C atoms, wherein furthermore, one or more CH2 groups in these groups may each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O-, -O-CO- in such a way that the O atoms are not directly connected to one another, and wherein furthermore, one or more H atoms may be replaced by halogen,

[0590] represents

[0591] Z ST each independently of one another represents -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond,

[0592] L 1 and L 2 each independently of one another represents F, Cl, CF3 or CHF2,

[0593] p represents 1 or 2,

[0594] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0595] Among the ST compounds, the compounds of the following formula are particularly preferred

[0596]

[0597]

[0598] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 1 or 7

[0599]

[0600] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0601]

[0602] where n = 1, 2, 3, 4, 5, 6 or 7, preferably n = 3

[0603]

[0604]

[0605] In the compounds of formulae ST-3a and ST-3b, n preferably represents 3. In the compounds of formula ST-2a, n preferably represents 7.

[0606] Very particularly preferred mixtures according to the invention comprise one or more stabilizers selected from the compounds of formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1 and ST-12:

[0607]

[0608]

[0609] Based on the mixture, the compounds of formulae ST-1 to ST-19 are preferably each present in the liquid crystal mixture according to the invention in an amount of 0.005 - 0.5%.

[0610] If the mixture according to the invention comprises two or more compounds of formulae ST-1 to ST-18, then based on the mixture, in the case of two compounds, the concentration is correspondingly increased to 0.01 - 1%.

[0611] However, based on the mixture according to the invention, the total proportion of the compounds of formulae ST-1 to ST-18 should not exceed 2%.

[0612] Furthermore, the present invention relates to an electro-optical display having active matrix addressing, characterized in that as the dielectric it contains a liquid crystal medium according to claim 1 and wherein the display is a VA, SA-VA, IPS, U-IPS, FFS, UB-FFS, SA-FFS, PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, polymer-stabilized SA-VA or polymer-stabilized SA-FFS display.

[0613] The display according to the invention preferably has a bezel with a thickness of 10 mm or less, more preferably 5 mm or less, and very preferably 3 mm or less.

[0614] The present invention also relates to a method for manufacturing a display composed of a first and a second substrate, the method comprising at least the following steps:

[0615] i) dropping a liquid crystal according to one or more of claims 1 to 7 into a reservoir of a sealant for the liquid crystal, which is formed on the first substrate;

[0616] ii) bonding the second substrate to the first substrate; and

[0617] iii) curing the sealant.

[0618] For example, sealants for liquid crystal displays are disclosed in US2007 / 096056 A1, EP 1780587 A1, US 2003 / 0147034 A1 and EP 2381304A1.EP 1 559 735 A1, and EP 2 586 827 A1. The sealant used in the method according to the invention is preferably photochemically curable, and particularly preferably both photochemically curable and thermally curable.

[0619] The sealant used in the method according to the invention preferably contains a) one or more curable resins, which contain compounds each substituted by one or more epoxide groups (hereinafter referred to as "epoxides"), and / or b) one or more compounds each substituted by one or more acrylate or methacrylate groups (hereinafter referred to as "(meth)acrylates"), and / or c) one or more compounds substituted by epoxide groups and (meth)acrylate groups (hereinafter referred to as "epoxide acrylates").

[0620] Each of the components a), b) and c) here can be in the form of both monomers and oligomers. The choice of components is not limited in principle to specific compounds. The polymerizable compounds are preferably di-, tri- or poly-reactive, i.e., they contain two, three or more reactive epoxy and / or (meth)acrylate groups. Considering the lowest possible contamination of the liquid crystal with the sealant component, resins containing hydroxyl, sulfonyl or ether groups are preferred.

[0621] In addition to one or more compounds of formula I, the sealant used in the process according to the invention preferably contains

[0622] i) a free-radically curable resin;

[0623] ii) an epoxy resin;

[0624] iii) an epoxy curing agent.

[0625] Examples of free-radically curable resins are (meth)acrylates and unsaturated polyester resins, which can each be used alone or as a mixture of one or more such substances. Monomeric (meth)acrylates preferably contain two or more (meth)acrylate groups per molecule.

[0626] Examples of (meth)acrylates are urethane (meth)acrylates containing a urethane bridge and epoxy (meth)acrylates which carry one or more glycidyl groups in addition to one or more (meth)acrylate groups.

[0627] Examples of urethane (meth)acrylates are compounds obtained by the reaction between a diisocyanate (such as isophorone diisocyanate) and a compound capable of adding to the isocyanate (such as acrylic acid or hydroxyethyl acrylate).

[0628] These derivatives can contain chain extensions of caprolactone or polyols and can be commercially obtained under the trade names U 122P, U 3,40P, U 4HA and U 1084A (Shin-Nakamura Chemical), and KRM 7595, KRM 7610 and KRM 7619 (Daicel Cytec Co.).

[0629] Examples of epoxy (meth)acrylates are derivatives of epoxy resins such as bisphenol A epoxy resin or propylene glycol diglycidyl ether and (meth)acrylic acid, and are commercially available under the trade names EA-1020, EA-6320 and EA-5520 (Shin-Nakamura Chemical), and EPOXY ESTER 70PA and EPOXY ESTER 3002A. Other examples of suitable (meth)acrylates are methyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, (poly)ethylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate and glycerol dimethacrylate.

[0630] Groups of free-radically curable resins also include epoxy acrylates which contain one or more (meth)acrylate groups and one or more epoxy groups per molecule and which are prepared by reacting the above-mentioned epoxy resins with (meth)acrylic acid moieties in the presence of a base; they also include compounds prepared by reacting half the equivalents of a bifunctional or polyfunctional isocyanate with half the equivalents of a hydroxy-containing (meth)acrylate and then with half the equivalents of glycidol; they also include compounds prepared by reacting a methacrylate substituted with an isocyanate group with glycidol.

[0631] Such materials are available, for example, under the trade names UVAC1561 (Daicel Cytec) and 4HBAGE (Nippon Kasei).

[0632] Examples of potential epoxy curing agents according to the invention are dicyandiamide, modified polyamines, hydrazides, 4,4'-diaminodiphenylsulfone, boron trifluoride / amine complexes, and imidazoles, guanidines, ureas, melamines and their derivatives.

[0633] Examples of modified polyamines are polyamines, amides of polyamines and epoxy adducts of Mannich-type modified polyamines.

[0634] Examples of polyamines are aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,2-diaminopropane, polyoxypropylene diamine, and polyoxypropylene triamine; cycloaliphatic polyamines such as isophoronediamine, methenediamine, bis(4-amino-3-methylcyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-aminoethylpiperazine, and 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane; aromatic polyamines such as m-phenylenediamine, p-phenylenediamine, toluene-2,4-diamine, toluene-2,6-diamine, mesitylene-2,4-diamine, mesitylene-2,6-diamine, 3,5-diethyltoluene-2,4-diamine, and 3,5-diethyltoluene-2,6-diamine, benzidine, 4,4-diaminodiphenylmethane, 2,5-naphthalenediamine, and 2,6-naphthalenediamine; and imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-aminopropylimidazole.

[0635] The epoxy adducts are prepared by adding epoxides to polyamines, and this addition is familiar to those skilled in the art. The epoxides are preferably aliphatic compounds, aromatic compounds, etc. These compounds can be used alone or in admixture with other epoxides.

[0636] Examples of cycloaliphatic epoxides are polyglycidyl ethers of polyols containing at least one aliphatic ring, cyclohexene oxide, or cyclopentene oxide and their derivatives, especially the following saturated derivatives: bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-1-methylcyclohexyl 3,4-epoxy-1-methylcyclohexanecarboxylate, 6-methyl-3,4-epoxycyclohexylmethyl-6-methyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-3-methylcyclohexylmethyl 3,4-epoxy-3-methylcyclohexanecarboxylate, 3,4-epoxy-5-methylcyclohexylmethyl 3,4-epoxy-5-methylcyclohexanecarboxylate, 2(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexanemetadioxane, bis(3,4-epoxycyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylenebis(3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, and di-2-ethylhexyl epoxyhexahydrophthalate.

[0637] Commercially available products containing such compounds are, for example, UVR-6100, UVR-6105, UVR-6110, UVR-6128, and UVR-6200 (Union Carbide); Celloxide 2021, Celloxide 2021P, Celloxide 2081, Celloxide 2083, Celloxide 2085, Celloxide 2000, Celloxide 3000, Cyclomer A200, Cyclomer M100, Cyclomer M101, Epolead GT-301, Epolead GT-302, Epolead 401, Epolead403, ETHB, and Epolead HD300 (Daicel Chemical Industries, Ltd.), and KRM-2110 and KRM-2199 (ADEKA Corp.).

[0638] Examples of aromatic epoxides are polyglycidyl ethers of polyhydric phenols or their alkylene oxide adducts, which contain at least one aromatic ring, such as glycidyl ethers of bisphenol A, bisphenol F, or their alkylene oxides, and epoxy-novolac resins.

[0639] Examples of aliphatic epoxides are polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts, polyglycidyl esters of long-chain aliphatic polycarboxylic acids, glycidyl (meth)acrylates, especially 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol tetraglycidyl ether, dipentaerythritol hexaglycidyl ether, polyethylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether; polyglycidyl ethers of polyether polyols, which are prepared by adding one or more alkylene oxides to aliphatic polyols, such as propylene glycol, trimethylolpropane, and glycerol; and diglycidyl esters of long-chain aliphatic dicarboxylic acids. In addition, preferably, monoglycidyl ethers of higher aliphatic alcohols, the following monoglycidyl ethers: phenol, cresol, butylphenol, or polyether alcohols prepared by adding alkylene oxides to these phenols, glycidyl esters of higher fatty acids, epoxidized soybeans, octyl epoxystearate, butyl epoxystearate, and epoxidized polybutadiene.

[0640] Examples of commercially available aromatic or aliphatic epoxides are Epikote 801 and Epikote 828 (YukaShell Epoxy Co., Ltd.); PY-306, 0163 and DY-022 (Ciba Specialty Chemicals); KRM-2720, EP-3300, EP-4000, EP-4901, EP-4010, EP-4080, EP-4900, ED-505 and ED-506 (ADEKA); EpoliteM 1230, Epolite EHDG-L, Epolite 40E, Epolite 100E, Epolite 200E, Epolite 400E, Epolite 70P, Epolite 200P, Epolite 400P, Epolite 1500NP, Epolite 1600, Epolite80MF, Epolite 100MF, Epolite 4000, Epolite 3002 and Epolite FR-1500 (KyoeishaChemical); Santoto ST0000, YD-716, YH-300, PG-202, PG-207, YD-172 and YDPN638 (TohtoKasei Co., Ltd.); TEPIC-S (Nissan Chemical Industries, Ltd.); and Epichlon N 665, Epichlon N 740, Epichlon HP-7200 and Epichlon HP-4032 (DIC Corp.).

[0641] The polyamides are obtained in a manner known to those skilled in the art by the reaction of polyamines with carboxylic acids such as adipic acid, sebacic acid, phthalic acid or isophthalic acid.

[0642] Mannich-modified polyamines are prepared by reacting polyamines with aldehydes such as formaldehyde and phenols such as phenol, cresol, xylenol, tert-butylphenol or resorcinol.

[0643] Examples of hydrazides are oxalic dihydrazide, malonic dihydrazide, succinic dihydrazide, glutaric dihydrazide, adipic dihydrazide, suberic dihydrazide, azelaic dihydrazide, sebacic dihydrazide and phthalic dihydrazide.

[0644] Examples of urea derivatives are 3(3,4-dichlorophenyl)-1,1-dimethylurea, isophorone diisocyanate dimethylurea and tolylene diisocyanate dimethyl-urea.

[0645] Examples of epoxy resins (III) are polyglycidyl ethers of polyphenols, such as hydroquinone, resorcinol, catechol and phloroglucinol; polyglycidyl ethers of fused aromatic hydroxy compounds, such as naphthol, biphenylol, methylene bisphenol (bisphenol F), methylene bis(ortho-cresol), ethylidene bisphenol, isopropylidene bisphenol (bisphenol A), 4,4'-dihydroxybenzophenone, isopropylidene bis(ortho-cresol), tetrabromobisphenol A, 1,3-bis(4-hydroxycumylbenzene), 1,4-bis(4-hydroxycumylbenzene), 1,1,3-tris(4-hydroxyphenyl)butane, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, thio-bisphenol, sulfo-bisphenol, oxy-bisphenol, phenol novolac, ortho-cresol novolac, ethylphenol novolac, butylphenol novolac, octylphenol novolac, resorcinol novolac and terpene bisphenol; furthermore, polyglycidyl ethers of polyols, such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, thiodiglycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol and bisphenol A / ethylene oxide adduct; homopolymers or copolymers of glycidyl esters of aliphatic, aromatic or cycloaliphatic polycarboxylic acids, such as maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid and endo-methylenetetrahydrophthalic acid or glycidyl methacrylate; furthermore, epoxides containing glycidylamino groups, such as N,N-glycidylaniline, bis(4-(N-methyl-N-glycidylamino)phenyl)methane and diglycidyl-o-toluidine; epoxidized cycloalkenes, such as vinylcyclohexene dioxide, dicyclopentadiene dioxide, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methyl-cyclohexylmethyl-6-methylcyclohexanecarboxylate and bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate; epoxidized conjugated polyenes, such as epoxidized polybutadiene, epoxidized acrylonitrile-butadiene copolymer and epoxidized styrene-butadiene copolymer; and heterocyclic compounds, such as triglycidyl isocyanurate.

[0646] In a preferred embodiment, the sealant used in the process according to the invention comprises other components, such as inorganic fillers, or silanes for improving the adhesion strength and waterproof properties, organic solvents, pigments, defoamers, conductive additives, leveling agents and the like.

[0647] The sealant used in the process according to the invention is prepared, for example, by mixing and dissolving a predetermined amount of the components for photocuring, the components for thermal curing, and, if necessary, various additives, and subsequently homogenizing the mixture using known mixing devices (such as a three-roll mill, a sand mill or a ball mill).

[0648] The sealant used in the process according to the invention is particularly suitable for sealing liquid crystal displays produced by the ODF process. The liquid or liquid crystal is not restricted in any way.

[0649] The process is particularly suitable for sealing liquid crystal displays which contain a liquid crystal having polymerizable components (reactive mesogens) and / or a separate liquid crystal substance containing unsaturated groups, such as alkenyl or cyclohexene-1,4-diyl units. The reactive mesogens preferably contain one or more (meth)acrylate groups.

[0650] For the production of liquid crystal displays, spacers are added to the sealant and the liquid crystal medium in order to produce a precisely defined spacing of the substrates according to the application and thus a precisely defined cell thickness of the display, usually 2 - 8 μm. First, the sealant is applied to one of the two glass substrates, and then the liquid crystal in an amount precisely corresponding to the internal volume of the finished liquid crystal display. After the two substrates have been combined, the display is irradiated with a dose of UV light of 1000 mJ to 18000 mJ, during which the two substrates are pressed together. The sealant is then thermally cured at 110 °C to 140 °C for 1 to 3 hours.

[0651] During the manufacture of the display according to the invention, after having been dispensed onto the substrate, the liquid crystal medium comes into contact with the sealant before the sealant cures. Surprisingly, the reactivity of the liquid crystal medium according to the invention is advantageously low such that no detectable degradation of the LC occurs before, during or after the sealant cures, such that no visible edge non-uniformities are observed in the final display.

[0652] In the case of the liquid crystal medium according to the invention, it is advantageous to have a nematic phase of ≤ -20 °C to ≥ 70 °C, particularly preferably ≤ -30 °C to ≥ 80 °C, very particularly preferably ≤ -40 °C to ≥ 90 °C.

[0653] The medium according to the invention has a clearing temperature of 65 °C or higher, preferably 67 °C or higher, particularly 70 °C or higher.

[0654] The expression "having a nematic phase" here means on the one hand that no smectic phase and no crystallization are observed at low temperatures at the corresponding temperature and on the other hand that it does not become clear when heated from the nematic phase. The low temperature studies are carried out in a flow viscometer at the corresponding temperature and are checked by storing in a test cell having a layer thickness corresponding to electro-optical use for at least 100 hours. If the storage stability in the corresponding test cell at -20 °C is 1000 hours or more, the medium is called stable at this temperature. At the temperatures of -30 °C and -40 °C, the response times are 500 hours and 250 hours respectively. At high temperatures, the clearing point is measured in a capillary by conventional methods.

[0655] The liquid crystal mixture preferably has a nematic phase range of at least 60 K and a flow viscosity ν of at most 30 mm at 20 °C 2 ·s -1 at 20 °C 20 。

[0656] The mixture is nematic at a temperature of -20 °C or lower, preferably -30 °C or lower, very preferably -40 °C or lower.

[0657] The value of the birefringence Δn in the liquid crystal mixture generally lies between 0.07 and 0.16, preferably between 0.08 and 0.15, very preferably between 0.09 and 0.14.

[0658] In a preferred embodiment of the invention, the birefringence range of the medium is from 0.090 to 0.110, preferably from 0.095 to 0.109, in particular from 0.098 to 0.108.

[0659] The liquid crystal mixture according to the invention has a dielectric anisotropy Δε of from -1.5 to -8.0, preferably from -2.0 to -4.0, in particular from -2.5 to -3.5.

[0660] The rotational viscosity γ1 at 20 °C is preferably ≤ 150 mPa·s, in particular ≤ 130 mPa·s.

[0661] The liquid crystal medium according to the invention has a relatively low threshold voltage (V0) value. They are preferably in the range from 1.7 - 3.0 V, particularly preferably ≤ 2.7 V and very particularly preferably ≤ 2.5 V.

[0662] For the purposes of the present invention, the term "threshold voltage" refers to the capacitive threshold (V0), also known as the Freedericks threshold, unless expressly stated otherwise.

[0663] Furthermore, the liquid crystal medium according to the invention has a high voltage holding ratio value in the liquid crystal cell.

[0664] Generally, liquid crystal media having a low addressing voltage or threshold voltage exhibit a lower voltage holding ratio than those having a higher addressing voltage or threshold voltage, and vice versa.

[0665] For the present invention, the term "dielectrically positive compound" denotes a compound having Δε > 1.5, the term "dielectrically neutral compound" denotes those having -1.5 ≤ Δε ≤ 1.5 and the term "dielectrically negative compound" denotes those having Δε < -1.5. Here, the dielectric anisotropy of the compound is determined by dissolving 10% of the compound in a liquid crystal host in at least one test cell and measuring the capacitance of the resulting mixture, the test cell having a layer thickness of 20 μm and a homeotropic and planar surface alignment at 1 kHz in each case. The measurement voltage is generally 0.5 V - 1.0 V, but always below the capacitance threshold of the respective liquid crystal mixture under investigation.

[0666] All temperature values described in the present invention are given in °C.

[0667] The mixtures according to the invention are suitable for all VA-TFT applications, such as, for example, VAN, MVA, (S)-PVA, ASV, PSA (polymer sustained VA) and PS-VA (polymer stabilized VA). They are furthermore suitable for IPS (in-plane switching) and FFS (fringe field switching) applications with negative Δε.

[0668] It goes without saying for a person skilled in the art that the VA, IPS or FFS mixtures according to the invention may also contain compounds in which, for example, H, N, O, Cl and F are replaced by the corresponding isotopes.

[0669] The compounds of formula P are optionally added to the mixtures according to the invention in a concentration of preferably 0.01 to 5% by weight, particularly preferably 0.2 to 2% by weight. These mixtures may also optionally contain initiators, as described, for example, in U.S. 6,781,665. The initiator (for example Irganox-1076 from BASF) is preferably added in an amount of 0% to 1% to the mixture containing the polymerizable compound. This type of mixture can be used for the so-called polymer stabilized VA mode (PS-VA) or PSA (polymer sustained VA), where, after filling the display panel, it is intended to polymerize the reactive mesogens in the liquid crystal mixture. The prerequisite is that the liquid crystal compounds of the LC host do not react under the polymerization conditions of the reactive mesogens (i.e., generally when exposed to UV in the wavelength range of 320 to 360 nm). Liquid crystal compounds having alkenyl side chains (such as, for example, CC-3-V) do not show a reaction (UV polymerization) under the polymerization conditions for RM, and thus, in the present context, such compounds should not be regarded as RM.

[0670] The compounds according to the invention can be synthesized by or analogous to known methods described in the literature (for example in standard works such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart) under reaction conditions known and suitable for said reactions. Variants known per se can also be used here, but are not mentioned further here. In particular, they can be prepared as described in the following reaction schemes or analogous to the following reaction schemes. Other methods for preparing the compounds according to the invention can be obtained from the examples.

[0671] Other mesogenic compounds not specifically mentioned above can also optionally and advantageously be used in the media according to the invention. Such compounds are known to the person skilled in the art. Detailed Description

[0672] The following examples illustrate the invention but do not limit it. However, they show the person skilled in the art the preferred mixture concept, as well as the compounds preferably used and their respective concentrations, and their combinations with each other. In addition, the examples illustrate which properties and combinations of properties are achievable.

[0673] For the present invention and in the following examples, the structures of the liquid crystal compounds are represented by abbreviations and converted into chemical formulas according to Tables A to C below. All groups C m H 2m+1 、C n H 2n+1 、and C l H 2l+1 or C m H 2m-1 、C n H 2n-1 and C l H 2l-1 are straight-chain alkyl groups or alkylene groups, each having n, m, and l carbon atoms in each case. Preferably, n, m, and l are independently 1, 2, 3, 4, 5, 6, or 7. Table A shows the codes for the ring elements of the compound nucleus, Table B lists the bridging units, and Table C lists the symbolic meanings of the left- and right-hand end groups of the molecule. The abbreviation consists of the code for the ring element with an optional linking group, followed by a first hyphen and the left-hand end group code, and a second hyphen and the right-hand end group code. Table D shows exemplary structures of the compounds and their respective abbreviations.

[0674] Table A: Ring elements

[0675]

[0676]

[0677]

[0678]

[0679] Table B: Bridging units

[0680]

[0681] Table C: End groups

[0682]

[0683]

[0684] wherein n and m are each integers, and the three dots "..." are placeholders for other abbreviations from the table.

[0685] In addition to the compounds of formula I, IIA, IIB, IIC and / or IID, IVa, IVb and V, the mixtures according to the invention optionally comprise one or more of the compounds mentioned below.

[0686] The following abbreviations are used:

[0687] (n, m, k and l are each independently of one another integers, preferably from 1 to 9, preferably from 1 to 7, k and l may also be 0 and are preferably from 0 to 4, more preferably 0 or 2 and most preferably 2, n is preferably 1, 2, 3, 4 or 5, in the combination "-nO-", it is preferably 1, 2, 3 or 4, preferably 2 or 4, m is preferably 1, 2, 3, 4 or 5, in the combination "-Om", it is preferably 1, 2, 3 or 4, more preferably 2 or 4. The combination "-lVm" is preferably "2V1").

[0688] Table D

[0689]

[0690]

[0691]

[0692]

[0693]

[0694]

[0695]

[0696]

[0697]

[0698]

[0699]

[0700]

[0701]

[0702]

[0703]

[0704]

[0705] Table E

[0706] Table E shows the chiral dopants that can be added to the LC medium according to the present invention.

[0707]

[0708]

[0709]

[0710]

[0711]

[0712] Table F

[0713] Table F shows illustrative reactive mesogenic compounds (RMs) that can be used in the LC medium according to the present invention.

[0714]

[0715]

[0716]

[0717]

[0718]

[0719]

[0720]

[0721]

[0722]

[0723]

[0724]

[0725]

[0726]

[0727]

[0728]

[0729]

[0730]

[0731]

[0732]

[0733]

[0734]

[0735] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, which are preferably selected from the polymerizable compounds of formulas RM-1 to RM-155. Among these compounds, the compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-102, RM-103, RM-109, RM-117, RM-120, RM-121, RM-122 and RM-145 to RM-153 are particularly preferred.

[0736] In another preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds selected from formulas RM-145 to RM-152, very preferably from formulas RM-147 to RM-152.

[0737] Table G

[0738] Table G shows self-aligning additives for vertical alignment in LC media that can be used together with the polymerizable compounds of formula P in SA-VA and SA-FFS displays according to the invention:

[0739]

[0740]

[0741]

[0742]

[0743]

[0744]

[0745]

[0746]

[0747]

[0748]

[0749]

[0750] In a preferred embodiment, the LC media, SA-VA and SA-FFS displays according to the invention comprise a combination of one or more SA additives (selected from formulas SA-1 to SA-48, preferably formulas SA-14 to SA-48, very preferably formulas SA-20 to SA-34 and SA-44) and one or more RMs of formula P.

[0751] Working Examples:

[0752] The following examples are intended to illustrate the invention and not to limit it. In the examples, m.p. represents the melting point and T (N,I) represents the clearing point of the liquid crystal substance in degrees Celsius; further: C represents the crystalline solid state, S represents the smectic phase (the subscript indicates the phase type), N represents the nematic phase, Ch represents the cholesteric phase, I represents the isotropic phase, T g represents the glass transition temperature. The value between the two symbols represents the transition temperature in degrees Celsius.

[0753] The host mixture used to determine the optical anisotropy Δn of a single compound is the commercial mixture ZLI-4792 (Merck KGaA). The dielectric anisotropy Δε is determined using the commercial mixture ZLI-2857. The physical data of the compound to be studied are obtained from the change in the dielectric constant of the host mixture after addition of the compound to be studied and extrapolated to 100% of the compound used. Usually, depending on solubility, 10% of the compound to be studied is dissolved in the host mixture.

[0754] Unless otherwise indicated, parts or percentage data represent parts by weight or percentages by weight. In the context:

[0755] V o represents the threshold voltage at 20 °C, capacitive [V],

[0756] n e represents the extraordinary refractive index at 20 °C and 589 nm,

[0757] n o represents the ordinary refractive index at 20 °C and 589 nm,

[0758] Δn represents the optical anisotropy at 20 °C and 589 nm,

[0759] ε ⊥ represents the dielectric constant perpendicular to the director at 20 °C and 1 kHz,

[0760] ε || represents the dielectric constant parallel to the director at 20 °C and 1 kHz,

[0761] Δε represents the dielectric anisotropy at 20 °C and 1 kHz,

[0762] cl.p., T(N,I) represents the clearing point [°C],

[0763] γ1 represents the rotational viscosity measured at 20 °C [mPa·s],

[0764] K1 represents the elastic constant, the "splay" deformation at 20 °C [pN],

[0765] K2 represents the elastic constant, the "twist" deformation at 20 °C [pN],

[0766] K3 represents the elastic constant, the "bend" deformation at 20 °C [pN], and

[0767] LTS represents the low temperature stability (nematic phase) measured as specified in the test cell or bulk,

[0768] Unless otherwise specified, all temperature values indicated in this application, such as the melting point T(C,N), the transition from the smectic phase (S) to the nematic phase (N) T(S,N), and the clearing point T(N,I) or cl.p., are expressed in degrees Celsius (°C).

[0769] The term "threshold voltage" used in the present invention refers to the capacitive threshold (V0), which is also referred to as the Freedericksz threshold, unless otherwise specified. In the examples, as usual, the optical threshold can also be indicated for a 10% relative contrast (V 10 )

[0770] The display for measuring the capacitive threshold voltage consists of two plane-parallel glass outer plates spaced 20 μm apart. Each outer plate has an electrode layer on the inner side and an unrubbed polyimide alignment layer on the top, which results in a homeotropic edge alignment of the liquid crystal molecules.

[0771] The display or test cell for measuring the tilt angle consists of two plane-parallel glass outer plates spaced 4 μm apart. Each outer plate has an electrode layer on the inner side and a polyimide alignment layer on the top, where the two polyimide layers are rubbed in anti-parallel to each other and result in a homeotropic edge alignment of the liquid crystal molecules.

[0772] The polymerizable compound is polymerized in the display or test cell by irradiating with UV light of a defined intensity for a predetermined time while applying a voltage (usually 10 V - 30 V alternating current, 1 kHz) to the display. In the examples, unless otherwise specified, a metal halide lamp and an intensity of 100 mW / cm 2 are used for polymerization. The intensity is measured using a standard meter (Hoenle UV-meter high end with a UV sensor).

[0773] The tilt angle is determined using the Mueller Matrix Polarimeter "AxoScan" from Axometrics. Small values (i.e., large deviations from the 90° angle) correspond to large tilts here.

[0774] Unless otherwise specified, the term "tilt angle" represents the angle between the LC director and the substrate, and "LC director" represents the preferred orientation direction of the optical principal axis of the LC molecules in a layer of LC molecules with a uniform orientation, which corresponds to the molecular long axis in the case of rod-like uniaxial positive birefringent LC molecules.

[0775] Unless otherwise indicated, VHR is measured at 20 °C (VHR 20 ) and at 100 °C (VHR 100It is measured after 5 minutes in an oven at (). Unless otherwise indicated more precisely, the voltage used has a frequency ranging from 1 Hz to 60 Hz.

[0776] The accuracy of the VHR measurement depends on the corresponding VHR value. The accuracy decreases as the value decreases. The deviations typically observed in the case of values in various amplitude ranges are summarized in order of magnitude in the following table.

[0777]

[0778]

[0779] The stability against UV irradiation was studied using a xenon lamp NXE1500B in a commercially available instrument "Suntest CPS+" from Heraeus, Germany. Unless otherwise explicitly indicated, the sealed test cells were irradiated for 2.0 hours without additional heating. The irradiation power in the wavelength range from 300 nm to 800 nm was 765 W / m 2 V. A UV "cut-off" filter with a cut-off wavelength of 310 nm was used in sequence to mimic the so-called window glass mode. In each series of experiments, at least four test cells were studied for each condition, and each result was indicated as the average corresponding to each measurement.

[0780] The decrease in the voltage holding ratio (ΔVHR) usually caused by exposure (e.g., by UV irradiation or by LCD backlight) is determined according to the following equation (1):

[0781] ΔVHR(t) = VHR(t) - VHR(t = 0) (1).

[0782] To study the low-temperature stability, also known as "LTS", i.e., the stability of the LC mixture against the spontaneous crystallization of each component or the appearance of the smectic phase in the bulk at low temperature, as the case may be, several sealed bottles each containing approximately 1 g of the material were stored at one or more given temperatures, usually -10 °C, -20 °C, -30 °C, and / or -40 °C, and visually inspected at regular intervals to check if a phase change was observed. Once the first of the samples showed a change at a given temperature, the time was noted. The time until no change was observed until the last inspection was noted as the corresponding LTS.

[0783] The ion density was measured using a commercially available LC material property measurement system model 6254 from Toyo Corporation, Japan, using a VHR test cell (JSR Corp., Japan) with AL16301 polyimide having a cell gap of 3.2 μm, and the resistivity was calculated therefrom. The measurement was carried out after 5 min in an oven stored at 60 °C or 100 °C.

[0784] The so-called "HTP" refers to the helical twisting power (in μm) of an optically active or chiral substance in an LC medium. Unless otherwise indicated, HTP is measured in a commercially available nematic LC host mixture MLD-6260 (Merck KGaA) at a temperature of 20 °C.

[0785] The clearing point is measured using a Mettler Thermosystem FP900. The optical anisotropy (Δn) is measured using an Abbe-Refraktometer H005 (sodium spectral lamp Na10, at 589 nm, 20 °C). The dielectric anisotropy (Δε) is measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS 2096-R1). The switching voltage (V0) is measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS 2096-R1). The rotational viscosity (γ1) is measured using a TOYO LCM-2 (0002) at 20 °C (γ1 negative cell with JALS-2096-R1). The elastic constant (K1, splay) is measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS 2096-R1). K3: The elastic constant (K3, bend) is measured using an LCR-Meter E4980A / Agilent (G005) at 20 °C (ε-parallel cell with JALS 2096-R1).

[0786] Unless otherwise explicitly mentioned, all concentrations in this application are indicated in weight percentages and relate to the corresponding mixture as a whole (without solvent) containing all solid or liquid crystal components. Unless otherwise explicitly indicated, all physical properties are determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany and apply to a temperature of 20 °C.

[0787] The following mixture examples with negative dielectric anisotropy are particularly suitable for liquid crystal displays having at least one planar alignment layer, such as for example IPS and FFS displays, in particular UB-FFS (= ultra-bright FFS), and are suitable for VA displays.

[0788] Mixture examples

[0789] Mixture M1

[0790]

[0791]

[0792] Mixture M2

[0793]

[0794] Mixture M3

[0795]

[0796]

[0797] Mixture M4

[0798]

[0799] Mixture M5

[0800]

[0801]

[0802] Mixture M6

[0803] Mixture M6 contains the compound CCY-3-O2F:

[0804]

[0805]

[0806] Mixture M7

[0807] Mixture M7 contains the compound CY-3-O1(c3)

[0808]

[0809]

[0810]

[0811] Mixture M8

[0812] Mixture M8 contains the compound COY-(c5)-O2

[0813]

[0814]

[0815]

[0816] Mixture M9

[0817] Mixture M9 contains the compound CCY-(c3)2-O2

[0818]

[0819]

[0820] Mixture M10

[0821] Mixture M10 contains the compound B(S)-2O-O1(c5)

[0822]

[0823]

[0824]

[0825] Polymerizable mixture examples

[0826] Mixture example P1

[0827] Mixture Example P1 consists of: 99.595% of Mixture M-1, 0.40% of Compound RM-1

[0828]

[0829] and 0.005% of Compound ST-3a-1

[0830]

[0831] Mixture example P2

[0832] Mixture Example P2 consists of: 99.595% of Mixture M-2, 0.40% of Compound RM-1 and 0.005% of Compound ST-3a-1.

[0833] Mixture example P3

[0834] Mixture Example P3 consists of: 99.595% of Mixture M-3, 0.40% of Compound RM-1 and 0.005% of Compound ST-3a-1.

[0835] Mixture example P4

[0836] Mixture Example P4 consists of: 99.595% of mixture M-4, 0.40% of compound RM-1, and 0.005% of compound ST-3a-1.

[0837] Mixture example P5

[0838] Mixture Example P5 consists of: 99.595% of mixture M-5, 0.40% of compound RM-1, and 0.005% of compound ST-3a-1.

[0839] Mixture example P6

[0840] Mixture Example P6 consists of: 99.595% of mixture M-1, 0.40% of compound RM-19, and 0.005% of compound ST-3a-1.

[0841]

[0842] Mixture example P7

[0843] Mixture Example P7 consists of: 99.595% of mixture M-2, 0.40% of compound RM-19, and 0.005% of compound ST-3b-1

[0844]

[0845] Mixture example P8

[0846] Mixture Example P8 consists of: 99.595% of mixture M-3, 0.40% of compound RM-35

[0847]

[0848] and 0.005% of compound ST-3a-1

[0849]

[0850] Mixture example P9

[0851] Mixture Example P9 consists of: 99.595% of mixture M-1, 0.40% of compound RM-156

[0852]

[0853] and 0.005% of compound ST-3a-1.

[0854] Mixture example P10

[0855] Mixture Example P10 consists of: 99.595% of mixture M-2, 0.40% of compound RM-157

[0856]

[0857] and 0.005% of compound ST-3b-1

[0858]

Claims

1. A liquid crystal medium comprising a) one or more compounds of formula I, wherein R 11 represents a straight-chain, branched-chain or cyclic alkyl group having 1 to 12 C atoms, or a straight-chain, branched-chain or cyclic alkenyl group having at most 12 C atoms, wherein one or more H atoms are optionally replaced by fluorine R 12 represents a straight-chain, branched-chain or cyclic alkyl group having 1 to 12 carbon atoms, a straight-chain, branched-chain or cyclic alkoxy group having 1 to 11 carbon atoms, or a straight-chain, branched-chain or cyclic alkenyl group having at most 12 carbon atoms; and b) one or more compounds selected from the compounds of formulae IIA, IIB, IIC and IID, wherein R 2A ,R 2B ,R 2C and R 2D each independently of one another represent H, an alkyl or alkenyl group having at most 15 C atoms, which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where furthermore, in these groups one or more CH2 groups may be replaced by -O-, -S-, -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO- in such a way that O atoms are not directly linked to one another, L 1 to L 4 each independently represents F, Cl, CF3 or CHF2, Y represents H, F, Cl, CF3, CHF2 or CH3, Z 2 , Z 2B and Z 2D each independently represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF- or -CH=CHCH2O- p represents 0, 1 or 2, q represents 0 or 1, and v represents 1, 2, 3, 4, 5, or 6, and c) one or more compounds of formula IVa and one or more compounds of formula IVb wherein R 41 and R 42 each independently represents a straight-chain alkyl, alkoxy, alkenyl or alkoxyalkyl having at most 12 carbon atoms indicate and Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2- -COO-, -OCO-, -C2F4-, -C4H8-, or -CF═CF-, and d) one or more compounds of formula V wherein R 51 and R 52 , which independently represent an alkyl group having 1 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an alkoxyalkyl, alkenyl or alkenyloxy group having 2 to 7 carbon atoms, Represented identically or differently Z 51 ,Z 52 each independently represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and n is 1 or 2, wherein the medium comprises a compound of formula I-1-1 ， in a concentration range of 6% to 9%, and a compound of formula I-1-5 ， in a concentration range of 6% to 9%, and a compound of formula I-1-6 ， in a concentration range of 5% to 8%, and a compound of formula IVa-2-1 ， in a concentration range of 10% to 13%, and a compound of formula IVb-1-1 ， in a concentration range of 5% to 8%, and a compound of formula V-16-1 ， in a concentration range of 5% to 8%, and a compound of formula IIA-2-2 ， in a concentration range of 8 to 11%, and a compound of formula IIA-2-5 ， in a concentration range of 6 to 9%, and a compound of formula IIA-10-2 ， in a concentration range of 6% to 9%, and a compound of formula IIA-10-4 ， in a concentration range of 6 to 9%, and a compound of formula IIB-10-1 ， in a concentration range of 7 to 10%, and a compound of formula IIB-10-4 ， in a concentration range of 7 to 10%.

2. The liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds of formula I as defined in claim 1, wherein the groups R 11 and R 12 , independently of one another, represent straight-chain, branched or cyclic alkyl having 1 to 12 C atoms.

3. The liquid crystal medium according to claim 1, wherein the medium comprises one or more compounds of formula IIA and / or IIB as defined in claim 1, and one or more compounds of formula I-1 and one or more compounds of formula IVa-2 and one or more compounds of formula IVb-1 wherein alkyl, alkyl’ and alkyl* in formulae I-1, IVa-2 and IVb-1, independently of one another, represent a straight-chain alkyl group having 1, 2, 3, 4 or 5 carbon atoms.

4. The liquid crystal medium according to claim 1, wherein the medium comprises 80% to 100% by weight of the compounds of formula I-1-1, I-1-5, I-1-6, V-16-1, IVa-2-1, IVb-1-1, IIA-2-2, IIA-2-5, IIA-10-2, IIA-10-4, IIB-10-1 and IIB-10-4 as defined in claim 1.

5. The liquid crystal medium according to any one of claims 1 to 4, wherein the medium comprises a chiral dopant.

6. The liquid crystal medium according to any one of claims 1 to 4, wherein the medium comprises one or more polymerizable compounds of formula P P-Sp-A 1 -(Z 1 -A 2 ) z -R P wherein P represents a polymerizable group, Sp represents a spacer group or a single bond, A 1 ,A 2 which, independently of one another, represent an aromatic, heteroaromatic, cycloaliphatic or heterocyclic group, which may also contain fused rings and which is unsubstituted or mono- or polysubstituted by L, L represents F, Cl, -CN, P-Sp-, or a straight-chain, branched-chain or cyclic alkyl group having 1 to 25 C atoms, where one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, or -O-CO-O- in such a way that O- and / or S-atoms are not directly connected to each other, and where one or more H atoms are each optionally replaced by P-Sp-, F or Cl, Z 1 represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH2-CH2-CO-O-, -O-CO-CH2-CH2-, -CR 0 R 00 -, or a single bond R 0 ,R 00 independently represents H or an alkyl group having 1 to 12 C atoms, identically or differently R represents H, L, or P-Sp-, z is 0, 1, 2 or 3, n1 is 1, 2, 3 or 4.

7. The liquid crystal medium according to claim 6, wherein A 1 , A 2 the aromatic, heteroaromatic, alicyclic or heterocyclic group in the definition has 4 to 25 ring atoms.

8. The liquid crystal medium according to claim 6, wherein the polymerizable compound of formula P is polymerized.

9. A liquid crystal display comprising a medium according to any one of claims 1 to 8.

10. The liquid crystal display according to claim 9, wherein the display is a PSA display.

11. The liquid crystal display according to claim 10, wherein the display is a PS-VA, PS-IPS, PS-FFS, PS-UB-FFS, polymer-stabilized SA-VA or polymer-stabilized SA-FFS display.

12. The liquid crystal display according to claim 9, wherein the display is a VA, IPS, U-IPS, FFS, UB-FFS, SA-FFS or SA-VA display.

13. The liquid crystal display according to any one of claims 9 to 12, wherein the display has a bezel with a thickness of 10 mm or less.

14. Use of a liquid crystal medium according to any one of claims 1 to 8 in an electro-optical display.

15. A method for manufacturing a display having a bezel with a thickness of 10 mm or less and consisting of a first and a second substrate, said method comprising at least the following steps: i) dropping a liquid crystal medium according to any one of claims 1 to 8 into a reservoir of a sealing material for liquid crystals, which is formed on the first substrate; ii) joining the second substrate to the first substrate; and iii) curing the sealing material.

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