Liquid crystal medium

Abstract

The invention relates to a liquid crystal (LC) material as defined in claim 1, which has a negative dielectric anisotropy, and to the use thereof for optical, electro-optical and electronic purposes, for example in energy-saving LC displays, in particular displays based on the ECB, IPS or FFS effect.

Description

Technical Field

[0001] The present invention relates to liquid crystal (LC) media having negative dielectric anisotropy and their use for optical, electro-optical and electronic purposes, in particular in LC displays. Background Art

[0002] One of the currently used liquid crystal display (LCD) modes is the TN ("twisted nematic") mode. However, a disadvantage of TN LCDs is that their contrast ratio is strongly dependent on the viewing angle.

[0003] Also known are so-called VA ("vertically aligned") displays, which offer even wider viewing angles. 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 off state, the molecules of the LC layer are aligned perpendicular to the electrode surfaces (homeotropically) or have a tilted homeotropic alignment. When a voltage is applied to the two electrodes, the LC molecules realign parallel to the electrode surfaces.

[0004] Also known are so-called IPS ("in-plane switching") displays, which contain an LC layer between two substrates, with two electrodes arranged on only one of the two substrates and preferably having an intermeshing comb-like structure. When a voltage is applied to the electrodes, an electric field with a significant component parallel to the LC layer is generated between them. This results in a realignment of the LC molecules within the plane of the layer.

[0005] In addition, so-called FFS ("fringe field switching") displays have been reported (see, inter alia, SH Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which contain two electrodes on the same substrate, one of which is structured in a comb-like manner and the other is unstructured. This generates a strong so-called "fringe field," i.e., a strong electric field close to the electrode edges and having both a strong vertical component and a strong horizontal component throughout the cell. FFS displays have a low viewing angle dependence of the contrast. FFS displays generally contain an LC medium with positive dielectric anisotropy and an alignment layer, generally a polyimide alignment layer, which provides for planar alignment of the molecules of the LC medium.

[0006] FFS displays can be operated as active matrix or passive matrix displays. In the case of active matrix displays, the individual pixels are typically addressed by integrated non-linear active elements such as transistors (e.g., thin film transistors ("TFTs")), while in the case of passive matrix displays, the individual pixels are typically addressed according to multiplexing methods as known in the art.

[0007] Furthermore, FFS displays have been disclosed (cf. SH Lee et al., Appl. Phys. Lett. 73 (20), 1998, 2882-2883 and SH Lee et al., Liquid Crystals 39 (9), 2012, 1141-1148) which have an electrode design and layer thickness similar to those of FFS displays, but include a layer of an LC medium having negative dielectric anisotropy rather than a layer of an LC medium having positive dielectric anisotropy. LC media having negative dielectric anisotropy exhibit more favorable director orientations, with less tilted and more twisted orientations, than LC media having positive dielectric anisotropy, with the result that these displays have higher transmittance. The displays further include an alignment layer, preferably an alignment layer of 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-brightness FFS (UB-FFS)" mode displays. These displays require an LC medium having high reliability.

[0008] In newer types of VA displays, the uniform alignment of the LC molecules is limited to a number of relatively small domains within the LC cell. Disclinations, also known as tilted domains, can exist between these domains. VA displays with tilted domains offer greater contrast and viewing angle independence of grey shades compared to conventional VA displays. Furthermore, this type of display is easier to produce because additional electrode surface treatment (e.g., by rubbing) is no longer necessary to uniformly align the molecules in the on-state. Instead, the preferred orientation of the tilt angle or pretilt angle is controlled by special electrode design.

[0009] In so-called MVA ("Multi-Domain Vertical Alignment") displays, this is usually achieved by electrodes having protrusions that cause local pretilt. As a result, the LC molecules are aligned parallel to the electrode surface in different, defined cell areas and in different directions when a voltage is applied. This achieves "controlled" switching and prevents the formation of disruptive disclination lines. Although this arrangement improves the viewing angle of the display, it leads to a reduction in its light transmittance. A further development of the MVA uses protrusions on only one electrode side, while the opposite electrode has a slit, which improves the light transmittance. This slit electrode generates an inhomogeneous electric field in the LC cell when a voltage is applied, which means 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 a longer response time. In so-called PVA ("patterned VA") displays, the protrusions are completely superfluous because the two electrodes are structured on opposite sides by slits, which leads to increased contrast and improved light transmission, 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, it is required to shorten the response time of the display and to improve its contrast and brightness (transmittance).

[0010] Another development is the so-called PS ("polymer maintained") or PSA ("polymer maintained alignment") type displays, for which the term "polymer stabilized" is occasionally also used. In these, small amounts (e.g., 0.3% by weight, typically <1% by weight) of one or more polymerizable compounds, preferably polymerizable monomeric compounds, are added to the LC medium and, after the LC medium has been filled into the display, are polymerized or crosslinked in situ (usually by UV photopolymerization), optionally while a voltage is applied to the display electrodes. The polymerization takes place at a temperature at which the LC medium exhibits a liquid crystal phase, typically room temperature. The addition of polymerizable mesogens or liquid crystal compounds (also called reactive mesogens or "RMs") to the LC mixture has proven particularly suitable.

[0011] 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 RMs preferably occurs under applied voltage in the case of PS-VA and PS-OCB displays, with or without, preferably without, applied voltage in the case of PS-IPS displays. As can be verified in test cells, the PS(A) method leads to a pretilt in the cell. In the case of PS-VA displays, this pretilt has a positive effect on the response time. For PS-VA displays, standard MVA or PVA pixel and electrode layouts can be used. Furthermore, however, it is also possible to manage, for example, only one structured electrode side without protrusions, which significantly simplifies production and simultaneously results in very good contrast and very good light transmittance.

[0012] PS-VA displays are described, for example, in EP 1 170 626 A2, US 6,861,107, US 7,169,449, US 2004 / 0191428 A1, US 2006 / 0066793 A1 and US 2006 / 0103804 A1.

[0013] In particular, for monitors and, in particular, TV applications, there is a continuing demand for optimization of the response time, contrast, brightness (and therefore also transmittance) of LC displays. The PSA method offers key advantages here. In particular, in the case of PS-VA, PS-IPS, and PS-FFS displays, a reduction in the response time relative to the pretilt, which can be measured in a test cell, can be achieved without significantly adversely affecting other parameters.

[0014] Another problem observed in the prior art is that the use of conventional LC media in LC displays (including but not limited to PSA-type displays) often leads to inhomogeneities in the display, particularly when the LC media is filled into display cells manufactured using the one drop filling (ODF) method. This phenomenon is also known as "ODF inhomogeneity." It is therefore desirable to provide LC media that exhibit reduced ODF inhomogeneities.

[0015] Another problem observed in the prior art is that LC media used in PSA displays (including but not limited to PSA-type displays) often exhibit high viscosity and, therefore, long switching times. In order to reduce the viscosity and switching times of LC media, the prior art has proposed the addition of LC compounds containing alkenyl groups. However, it has been observed that LC media containing alkenyl compounds often exhibit reduced reliability and stability, as well as a reduced VHR, especially after exposure to UV radiation. This is a considerable disadvantage, particularly for use in PSA displays, since photopolymerization of RMs in PSA displays is typically carried out by exposure to UV radiation, which can lead to a reduction in the VHR of the LC medium.

[0016] Furthermore, there is a great need for PSA displays, as well as LC media and polymerizable compounds for such PSA displays, which enable high specific resistance over a wide operating temperature range, short response times even at low temperatures, low threshold voltages, low pretilt angles, a large number of grayscale shades, high contrast, and wide viewing angles, as well as high reliability and high values ​​of VHR after UV exposure, and, in the case of polymerizable compounds, low melting points and high solubility in LC host mixtures. In particular, there is a need for usable LC media in PSA displays for mobile applications that exhibit low threshold voltages and high birefringence.

[0017] One trend in displays is to achieve the fastest possible response time in order to have the best possible motion picture quality. In this regard, media with negative dielectric anisotropy have inherent disadvantages compared to LC media with positive dielectric anisotropy. On the other hand, mixtures with negative dielectric anisotropy enable higher transmittance in a standard FFS cell layout, so their use has a positive impact on power consumption and the environment. There is a need in the art to achieve both fast response times and higher transmittance. In particular, for mobile devices, there is a great demand for displays with high transmittance, which enables the use of lower intensity backlights, which therefore leads to longer battery life and, therefore, more sustainable products. Alternatively, displays with higher brightness can be achieved, especially with improved contrast in ambient light. In addition, the popularity of 8K and gaming monitors has led to an increased demand for LC display panels with higher refresh rates, and thus an increase in demand for LC media with faster response times.

[0018] Another important display trend is achieving high contrast. Contrast is described by the ratio between the display's bright and dark states. In LCDs, particularly in IPS / FFS technology, the dark state is strongly influenced by the scattering parameter, thus significantly impacting contrast. To improve contrast and reduce the scattering parameter, LC blends with high elastic constants are required. Current LC compounds / substances and LC blends are limited in achieving extremely high elastic constants. Therefore, new materials are needed to further improve the contrast of future displays.

[0019] Another disadvantage of media with negative dielectric isotropy compared to media with positive dielectric anisotropy may be relatively lower reliability, and despite having fundamentally superior optical properties, non-uniformity and image sticking effects may occur after thermal or optical stress on the display.

[0020] There is therefore still a great need for VA, FFS or PSA displays and LC media for VA, FFS or PSA displays, optionally comprising polymerizable compounds, which do not exhibit the above-mentioned disadvantages, or do so only to a lesser extent, and have improved properties. Summary of the Invention

[0021] The present invention was based on the object of providing novel suitable LC media which do not have the abovementioned disadvantages or have them to a reduced extent.

[0022] Surprisingly, it has now been found that liquid-crystalline media with a suitably high negative Δε, a suitable phase range, as well as Δn and a high LTS can be achieved using liquid-crystalline media according to claim 1, which do not exhibit the disadvantages of the materials of the prior art or at least exhibit these disadvantages to a significantly lesser extent.

[0023] The present invention relates to a liquid crystal medium comprising:

[0024] a) one or more compounds of formula ST

[0025]

[0026] in

[0027] R S1 represents a straight-chain alkyl radical having 1 to 12 C atoms or a branched-chain alkyl radical having 3 to 12 C atoms, wherein one or more CH2 groups in these radicals may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- is replaced in such a way that the O atoms are not directly attached to one another, and wherein one or more H atoms may be replaced by halogen,

[0028] R S2 represents H, alkyl or alkoxy radicals having 1 to 7 C atoms, or alkenyl radicals having 2 to 7 C atoms, where one or more H atoms in these radicals may be replaced by halogen,

[0029] W 1 , W 2 , W 3 , W 4 Identically or differently, represents O or CH2, and

[0030] r1 and r2 are independently 0 or 1, preferably r1 is 0 and r2 is 1;

[0031] b) one or more compounds of formula Ia:

[0032]

[0033] in

[0034] W stands for CH 4-s or an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms;

[0035] A, on each occurrence, identically or differently, represents a single bond or a straight-chain alkylene radical having 1 to 20 carbon atoms or a straight-chain alkenylene radical having 2 to 20 carbon atoms or a branched alkylene radical or alkenylene radical each having 3 to 12 carbon atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CH=CH-, -C(O)-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen and one or two H atoms may be replaced by a radical -Z S -HA a Replacement;

[0036] R S represents H, an alkyl group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms;

[0037] Z S Indicates -O-, -C(O)O-, -(CH2) z -or-(CH2) z O-, or single bond;

[0038] HA a express

[0039] R S1 , R S2 , R S3 and R S4, identically or differently, denote an alkyl group having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3;

[0040] G means H or R S or group Z S -HA a ;

[0041] z is an integer from 1 to 6, and

[0042] s is 2, 3 or 4;

[0043] c) one or more compounds of formula Ib:

[0044]

[0045] W stands for CH 4-s or an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms;

[0046] A, on each occurrence, identically or differently, represents a single bond or a straight-chain alkylene radical having 1 to 20 carbon atoms or a straight-chain alkenylene radical having 2 to 20 carbon atoms or a branched alkylene radical or alkenylene radical each having 3 to 12 carbon atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CH=CH-, -C(O)-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen and one or two H atoms may be replaced by a radical -Z S -HA b Replacement;

[0047] R S represents H, an alkyl group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms;

[0048] Z S Indicates -O-, -C(O)O-, -(CH2) z -or-(CH2) z O-, or single bond;

[0049] HA b express

[0050] R S1 , R S2 , R S3 and R S4 , identically or differently, denote an alkyl group having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3;

[0051] G means H or RS or group Z S -HA b ;

[0052] z is an integer from 1 to 6, and

[0053] s is 2, 3 or 4;

[0054] and

[0055] d) one or more compounds selected from the group consisting of compounds of formula IIA, IIB, IIC and IID

[0056]

[0057] in

[0058] R 2A , R 2B , R 2C and R 2D Identically or differently, represents H, a straight-chain alkyl or alkoxy radical having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy radical having 2 to 15 C atoms or a branched alkyl, alkoxy, alkenyl, alkenyloxy radical each having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- is replaced in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen,

[0059] L 1 and L 2 , each independently represents F, Cl, CF3 or CHF2,

[0060] Y represents H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, more preferably H,

[0061] 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-,

[0062] (O) represents O or a single bond,

[0063] p represents 0, 1 or 2,

[0064] q represents 0 or 1, and

[0065] v represents an integer from 1 to 6.

[0066] The present invention furthermore relates to an LC display comprising the LC medium according to the invention, in particular a VA, IPS, FFS or UB-FFS or PSA display, particularly preferably an FFS, UB-FFS, VA or PS-VA display.

[0067] The present invention furthermore relates to the use of the LC media according to the invention in IPS or FFS displays.

[0068] The present invention further relates to the use of the LC medium according to the invention in a PSA display, in particular in a PSA display comprising an LC medium, for generating a tilt angle in the LC medium by in situ polymerization of polymerizable reactive mesogens (RMs) in the PSA display, preferably in an electric or magnetic field.

[0069] The present invention also relates to a process for preparing an LC medium as described above and below, comprising the step of mixing one or more compounds of formula I with one or more compounds of formula IIA, IIB, IIC and / or IID, and optionally with one or more chiral dopants, and optionally with one or more polymerizable compounds, and optionally with further LC compounds and / or additives.

[0070] The present invention furthermore relates to the use of an LC medium according to the invention in polymer-stabilized SA-VA displays, and to polymer-stabilized SA-VA displays comprising an LC medium according to the invention.

[0071] The present invention also relates to a method for producing an LC display as described above and below, comprising the steps of filling or otherwise providing an LC medium between the substrates of the display, the LC medium optionally comprising one or more polymerisable compounds as described above and below, and optionally polymerising the polymerisable compounds.

[0072] The LC media according to the invention are characterized by a surprisingly high reliability and stability towards UV or backlight, and at the same time have the following advantageous properties, in particular when used in FFS displays:

[0073] -Excellent low temperature stability (LTS)

[0074] - improved contrast of the display,

[0075] -High transmittance of the display

[0076] -High definition brightness temperature,

[0077] -High voltage holding ratio,

[0078] -Low rotational viscosity

[0079] - Quick Switch,

[0080] - Fast response time, enabling LCDs with low power consumption to extend battery life in mobile devices,

[0081] -High elastic constant.

[0082] Preferred compounds of formula ST are selected from the group consisting of compounds of formula ST-1, ST-2 and ST-3, preferably compounds of formula ST-1 and ST-2:

[0083]

[0084]

[0085] in

[0086] R S1 has the above meanings, preferably denotes a straight-chain, branched or cyclic alkyl radical having 1 to 7 C atoms,

[0087] r is 0 or 1, preferably 0.

[0088] The compounds of formulae ST-1 and ST-2 are preferably selected from the following subformulae:

[0089]

[0090]

[0091]

[0092] Preferred compounds of formula ST-3 are ST-3a and ST-3b:

[0093]

[0094]

[0095] Compounds of formula Ia and Ib are described in EP 3354710 A1 and EP 3354709 A1, respectively.

[0096] In a preferred embodiment, the group W in formula Ia represents a methylene group and s is 2. In this embodiment, the compound of formula Ia is preferably selected from the compounds of formula Ia-1:

[0097]

[0098] in

[0099] R S3 represents H or an alkyl group having 1 to 6 C atoms, preferably H or ethyl;

[0100] t is 0 or 1, and

[0101] q is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.

[0102] Very preferably, the compound of formula Ia-1 is selected from the compounds of formula Ia-1-1 and Ia-1-2, in particular the compound of formula Ia-1-1

[0103]

[0104] wherein q is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9, preferably 1.

[0105] In a preferred embodiment, the group W in formula Ia represents an aromatic or heteroaromatic hydrocarbon radical having 4 to 40 C atoms, which comprises one, two, three or four aromatic rings, including fused rings, which may be linked directly or via an alkylene linker having 1 to 12 C atoms, wherein one or more H atoms are optionally replaced by alkyl or alkoxy radicals having 1 to 6 C atoms or alkenyl radicals having 2 to 6 carbon atoms, or by CN, CF3 or halogen, and wherein one or more CH2 groups may each independently of one another be replaced by -O-, -S-, -NH-, -N(C1-C4-alkyl)-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C- in such a way that the O or S atoms are not directly linked to one another.

[0106] Preferred aryl groups are benzene, naphthalene, anthracene, biphenyl, m-terphenyl, p-terphenyl and (phenylalkyl)benzene, where alkyl is a straight-chain alkyl group having 1 to 12 C atoms.

[0107] In this embodiment, the compound of formula Ia is preferably selected from the group consisting of compounds of formula Ia-2, Ia-3 and Ia-4:

[0108]

[0109]

[0110] Where HA represents H or HA a , and HA a , A and R S Each occurrence thereof, whether identical or different, has the meaning defined above, and

[0111] W 1 represents a straight-chain or branched, optionally unsaturated alkylene group having 1 to 12 C atoms, wherein one or more non-adjacent -CH2- groups may be replaced by -O-, and n independently represents 0, 1, 2, 3 or 4.

[0112] Preferred compounds of formula Ia-2 are selected from compounds of formula Ia-2-1:

[0113]

[0114] wherein n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0115] Preferred compounds of formula Ia-3 are selected from compounds of formula Ia-3-1:

[0116]

[0117] wherein n2, identically or differently, preferably identically, on each occurrence is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, and R S On each occurrence, identically or differently, preferably identically, represents alkyl having 1 to 6 C atoms, very preferably n-butyl.

[0118] Preferred compounds of formula Ia-4 are selected from compounds of formula Ia-4-1:

[0119]

[0120] Where A and R S A having the above-defined meanings and preferably A on each occurrence identically or differently, preferably identically, denotes an alkylene radical having 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, C atoms, and R S represents, identically or differently, preferably identically, on each occurrence, alkyl having 1 to 6 C atoms, very preferably n-butyl, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0121] Certain very preferred compounds of formula Ia are listed below:

[0122]

[0123]

[0124]

[0125]

[0126] In a preferred embodiment, the group W in formula Ib represents a methylene group and s is 2. In this embodiment, the compound of formula Ib is preferably selected from the compounds of formula Ib-1:

[0127]

[0128] in

[0129] R S3 represents H or an alkyl group having 1 to 6 C atoms, preferably H or ethyl;

[0130] t is 0 or 1, and

[0131] q is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.

[0132] Very preferably, the compound of formula Ib-1 is selected from the group consisting of compounds of formula Ib-1-1 and Ib-1-2:

[0133]

[0134] wherein q is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9, preferably 7.

[0135] Alternatively, the group W in formula Ib represents an aromatic or heteroaromatic hydrocarbon radical having 4 to 40 C atoms, comprising one, two, three or four aromatic rings, including fused rings which may be linked directly or via an alkylene linker having 1 to 12 C atoms, wherein one or more H atoms are optionally replaced by an alkyl radical having 1 to 6 C atoms, or an alkenyl radical having 2 to 6 carbon atoms, or CN, CF3 or halogen, and wherein one or more CH2 groups may each independently of one another be replaced by -O-, -S-, -NH-, -N(C1-C4-alkyl)-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C- in such a way that the O or S atoms are not directly linked to one another.

[0136] Preferred aryl groups are benzene, naphthalene, anthracene, biphenyl, m-terphenyl, p-terphenyl and (phenylalkyl)benzene, where alkyl is a straight-chain alkyl group having 1 to 12 C atoms.

[0137] In this embodiment, the compound of formula Ib is preferably selected from the group consisting of compounds of formula Ib-2, Ib-3 and Ib-4:

[0138]

[0139]

[0140] Where HA represents H or HA b , and HA b , A and R S Each occurrence thereof, whether identical or different, has the meaning defined above, and

[0141] W 1 represents a straight-chain or branched, optionally unsaturated alkylene group having 1 to 12 C atoms, wherein one or more non-adjacent -CH2- groups may be replaced by -O-, and n independently represents 0, 1, 2, 3 or 4.

[0142] Preferred compounds of formula Ib-2 are selected from compounds of formula Ia-2-1:

[0143]

[0144] wherein n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0145] Preferred compounds of formula Ib-3 are selected from compounds of formula Ib-3-1:

[0146]

[0147] wherein n2, identically or differently, preferably identically, on each occurrence is an integer from 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, and R S On each occurrence, identically or differently, preferably identically, represents alkyl having 1 to 6 C atoms, very preferably n-butyl.

[0148] Preferred compounds of formula Ib-4 are selected from compounds of formula Ib-4-1:

[0149]

[0150] Where A and R S A having the above-defined meanings and preferably A on each occurrence identically or differently, preferably identically, denotes an alkylene radical having 1 to 12, preferably 2, 3, 4, 5, or 6, very preferably 3, C atoms, and R S represents, identically or differently, preferably identically, on each occurrence, alkyl having 1 to 6 C atoms, very preferably n-butyl, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0151] Certain highly preferred compounds of formula Ib are listed below:

[0152]

[0153]

[0154]

[0155] Preferred compounds of formula IIA, IIB, IIC and IID are shown below:

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168] wherein the parameter a is 1 or 2, alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 carbon atoms, and alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 carbon 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-.

[0169] Compounds of the formulae IID-4 and IID-10, in which (O) represents O in particular, are very preferred.

[0170] Very preferred compounds of formula IID are selected from the following sub-formulae:

[0171]

[0172]

[0173]

[0174]

[0175]

[0176]

[0177] In a preferred embodiment, the medium comprises one or more compounds of formula IID-10a

[0178]

[0179] The radicals and parameters occurring therein have the meanings given above under formula IID, and

[0180] R 2 express where r is 0, 1, 2, 3, 4, 5, or 6 and s is 1, 2, or 3.

[0181] Preferred compounds of formula IID-10a are compounds IID-10a-1 to IID-10a-14.

[0182]

[0183]

[0184]

[0185] Particularly preferred mixtures of the present invention include one or more compounds of formula 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.

[0186] Preferred media according to the invention comprise at least one compound of formula IIC-1,

[0187]

[0188] wherein alkyl and alkyl* have the above-mentioned meanings.

[0189] In particular, the medium comprises one or more compounds of formula IIA-2 selected from the following subformulae:

[0190]

[0191]

[0192] Alternatively, it is preferred that the medium comprises, in addition to the compounds of the formulae IIA-2-1 to IIA-2-5, one or more compounds of the formulae IIA-2a-1 to IIA-2a-5:

[0193]

[0194] In particular, the medium comprises one or more compounds of formula IIA-10 selected from the following subformulae:

[0195]

[0196] Alternatively, it is preferred that the medium contains, in addition to the compounds of formulae IIA-10-1 to IIA-10-5, one or more compounds of formulae IIA-10a-1 to IIA-10a-5:

[0197]

[0198]

[0199] In particular, the medium comprises one or more compounds of formula IIB-10 selected from the following subformulae:

[0200]

[0201] Alternatively, it is preferred that the medium contains, in addition to the compounds of formulae IIB-10-1 to IIB-10-5, one or more compounds of formulae IIB-10a-1 to IIB-10a-5:

[0202]

[0203]

[0204] Alternatively, it is preferred that the medium comprises, in addition to the compound of formula IIC-1, one or more compounds of formulae IIC-1a-1 and IIC-1a-2:

[0205]

[0206] Here, alkyl denotes a straight-chain alkyl group having 1 to 7 C atoms, preferably 2 to 5 C atoms, very preferably ethyl.

[0207] The medium according to the invention preferably comprises one or more compounds of the formula III

[0208]

[0209] in

[0210] R 31 and R 32 each independently of one another represents H, alkyl or alkoxy having 1 to 15 C atoms, wherein one or more CH2 groups in these radicals may each independently of one another be -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- is replaced in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen,

[0211] A 31Represented independently of each other at each occurrence

[0212] a) 1,4-cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-,

[0213] b) 1,4-phenylene, in which one or two CH groups may be replaced by N, or

[0214] c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl,

[0215] wherein the groups a), b) and c) may be mono- or polysubstituted by halogen atoms,

[0216] n represents 0, 1 or 2, preferably 0 or 1,

[0217] Z 31 represents, independently of one another, -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

[0218] L 31 and L 32 each independently of one another represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and

[0219] W represents O or S.

[0220] The compound of formula III is preferably selected from the compounds of formula III-1 and / or III-2

[0221]

[0222] The radicals occurring therein have the same meanings as given above for formula III and are preferably

[0223] R 31 and R 32 each independently of one another is alkyl, alkenyl or alkoxy having up to 15 C atoms, more preferably one or two of them represents alkoxy, and

[0224] L 31 and L 32 Each preferably represents F.

[0225] Preferably, the compound of formula III-1 is selected from the compounds of formula III-1-1 to III-1-11, preferably formula III-1-6

[0226]

[0227]

[0228] in

[0229] Alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy* each independently represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 31 and L 32 Each independently represents F or Cl, preferably both are F.

[0230] The compound of formula III-2 is preferably selected from the compounds of formulae III-2-1 to III-2-10, preferably formula III-2-6,

[0231]

[0232]

[0233] in

[0234] Alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkoxy and alkoxy* each independently represent a straight-chain alkoxy group having 1 to 6 C atoms, and L 31 and L 32 Each independently represents F or Cl, preferably both are F.

[0235] Optionally, the medium comprises one or more compounds of formula IIIA-1 and / or IIIA-2

[0236]

[0237]

[0238] Among them L 31 and L 32 has the same meanings as given under formula III, (O) represents O or a single bond,

[0239] RIIIA represents an alkyl or alkenyl group having up to 7 C atoms or a group Cy-C m H 2m+1 -,

[0240] m and n, identical or different, are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1,

[0241] Cy denotes an alicyclic radical having 3, 4 or 5 ring atoms, which is optionally substituted by alkyl or alkenyl each having up to 3 C atoms, or halogen or CN, and preferably denotes cyclopropyl, cyclobutyl, cyclopentyl, cyclopent-1-enyl, cyclopent-2-enyl and cyclopent-3-enyl.

[0242] The compound of formula IIIA-1 and / or IIIA-2 is comprised in a medium alternatively or in addition to the compound of formula III, preferably additionally.

[0243] Highly preferred compounds of formula IIIA-1 and IIIA-2 are as follows:

[0244]

[0245]

[0246] wherein alkoxy represents a straight-chain alkoxy group having 1 to 6 C atoms or alternatively -(CH2) n F, wherein n is 2, 3, 4, or 5, preferably C2H4F.

[0247] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formula III-3

[0248]

[0249] in

[0250] R 31 , R 32 Identically or differently represent H, alkyl or alkoxy radicals having 1 to 15 C atoms, wherein one or more CH2 radicals in these radicals are optionally, independently of one another, replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- is substituted in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen.

[0251] The compound of formula III-3 is preferably selected from the compounds of formula III-3-1 to III-3-10

[0252]

[0253]

[0254] where R 32 represents an alkyl group having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl, or alternatively -(CH2) n F, wherein n is 2, 3, 4, or 5, preferably C2H4F.

[0255] In a preferred embodiment of the invention, the medium comprises one or more compounds of formulae III-4 to III-6, preferably formula III-5,

[0256]

[0257] where the parameters have the meanings given above, R 31 Preferably represents a straight chain alkyl group and R 32 Preferably denotes alkoxy, each having 1 to 7 C atoms.

[0258] In a preferred embodiment, the medium comprises one or more compounds of formula III selected from the group consisting of compounds of formulae III-7 to III-9, preferably formula III-8,

[0259]

[0260]

[0261] where the parameters have the meanings given above, R 31 Preferably represents a straight chain alkyl group and R 32 Preferably denotes alkoxy, each having 1 to 7 C atoms.

[0262] In a preferred embodiment, the medium comprises one or more compounds of formula IV,

[0263]

[0264] in

[0265] R 41 represents an alkyl group having 1 to 7 C atoms or an alkenyl group having 2 to 7 C atoms, preferably an n-alkyl group, particularly preferably one having 2, 3, 4 or 5 C atoms, and

[0266] R 42represents alkyl having 1 to 7 C atoms or alkoxy having 1 to 6 C atoms, preferably having 2 to 5 C atoms, alkenyl having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably vinyl or 1-propenyl, in particular vinyl.

[0267] The compound of formula IV is preferably selected from the compounds of formula IV-1 to IV-4,

[0268]

[0269] in

[0270] Alkyl and alkyl', independently of one another, denote an alkyl group having 1 to 7 C atoms, preferably 1 to 5 C atoms,

[0271] Alkenyl represents an alkenyl radical having 2 to 5 C atoms, preferably 2 to 4 C atoms, particularly preferably 2 C atoms,

[0272] alkenyl′ denotes alkenyl having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0273] Alkoxy represents an alkoxy group having 1 to 5 C atoms, preferably 2 to 4 C atoms.

[0274] The compound of formula IV-1 is preferably selected from the compounds of formulae IV-1-1 to IV-1-6:

[0275]

[0276] The compound of formula IV-2 is preferably selected from the compounds of formula IV-2-1 and IV-2-2

[0277]

[0278]

[0279] The compound of formula IV-3 is preferably selected from the compounds of formula IV-3-1, IV-3-2 and IV-3-3

[0280]

[0281] wherein alkyl has the meaning defined above, and wherein compounds of formula I are excluded from formula IV-3-2.

[0282] The compounds of formula IV-3-1, IV-3-2 and IV-3-3 are preferably selected from the following compounds:

[0283]

[0284]

[0285] Very preferably, the medium according to the invention comprises a compound of the formula IV-4, in particular a compound selected from the group consisting of the formulae IV-4-1 to IV-4-3

[0286]

[0287] The liquid-crystalline medium preferably additionally comprises one or more compounds of the formula IVa,

[0288]

[0289] in

[0290] R 41 and R 42 each independently of one another represents straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy having up to 12 C atoms, and express

[0291] Z 4 Represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8-, -CF=CF-.

[0292] Preferred compounds of formula IVa are shown below:

[0293]

[0294] in

[0295] Alkyl and alkyl* each independently of one another denote a straight-chain alkyl radical having 1 to 6 C atoms.

[0296] The medium according to the invention preferably comprises at least one compound of the formula IVa-1 and / or formula IVa-2.

[0297] The proportion of the compound of the formula IVa in the mixture as a whole is preferably less than 5% by weight, very preferably less than 2% by weight.

[0298] Preferably, the medium comprises one or more compounds of formulae IVb-1 to IVb-4, more preferably compounds of formulae IVb-1 to IVb-3

[0299]

[0300]

[0301] in

[0302] Alkyl and alkyl* each independently of one another denote a straight-chain alkyl radical having 1 to 6 C atoms, and

[0303] Alkenyl and alkenyl* each independently of one another represent straight-chain alkenyl having 2 to 6 C atoms.

[0304] Among the compounds of the formulae IVb-1 to IVb-3, the compound of the formula IVb-2 is particularly preferred.

[0305] Particularly preferred biphenyls are

[0306]

[0307] Here, alkyl* denotes an alkyl radical having 1 to 6 C atoms and preferably denotes n-propyl. The medium according to the invention particularly preferably comprises one or more compounds of the formula IVb-1-1 and / or IVb-2-3.

[0308] In a preferred embodiment, the medium according to the invention comprises one or more compounds of the formula V

[0309]

[0310] in

[0311] R 51 , R 52 represents an alkyl group having 1 to 7 C atoms, an alkoxy group having 1 to 7 C atoms, or an alkoxyalkyl group, an alkenyl group or an alkenyloxy group having 2 to 7 C atoms, Same or different, indicating

[0312] Z 51 , Z 52 each independently represents -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and

[0313] n is 1 or 2,

[0314] Compounds of formula CL are excluded.

[0315] The compound of formula V is preferably selected from the compounds of formula V-1, V-2 and V-3:

[0316]

[0317] The radicals occurring therein have the meanings given above for formula V.

[0318] The compound of formula V-1 is preferably selected from the compounds of formulae V-1-1 to V-1-8;

[0319] The compound of formula V-2 is preferably selected from the compounds of formulae V-2-1 to V-2-4; and

[0320] The compound of formula V-3 is preferably selected from the compounds of formulae V-3-1 to V-3-7:

[0321]

[0322]

[0323]

[0324] where R 51 and R 52 has the meaning shown in the above formula V.

[0325] R 51 and R 52 Preferably, each independently of one another represents straight-chain alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms.

[0326] Very preferred compounds of formula V-2-1 are selected from compounds of formula V-2-1a to V-2-1g

[0327]

[0328] Very preferred compounds of formula V-2-2 are selected from compounds of formula V-2-2a to V-2-2i

[0329]

[0330]

[0331] Preferably, the medium according to the invention comprises one or more compounds of formula CL

[0332]

[0333] in

[0334] R L represents H, a straight-chain or branched alkyl or alkoxy radical having 1 to 15 C atoms, or a straight-chain or branched alkenyl radical having 2 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly bonded to one another, and wherein, in addition, one or more H atoms may be replaced by halogen,

[0335] X L represents F, Cl, CN, CHF2, CF3, OCF3, or the same or different, with R L One of the meanings,

[0336] Y L Represents H, F, Cl or CH3.

[0337] The compound of formula CL is preferably selected from the group consisting of compounds of formula CL-1, CL-2 and CL-3.

[0338]

[0339] in

[0340] R L1 and R L2 , identically or differently have the meanings given above for formula I, and preferably denote an alkyl or alkenyl radical having 1 to 7 C atoms or 2 to 7 C atoms, respectively, where the CH2 radical may be replaced by a cyclopropane-1,2-diyl radical, and R L2 Alternatively represents an alkoxy group having 1 to 5 C atoms.

[0341] Very preferred compounds of formula CL are selected from the group consisting of compounds of formulae CL-3-1 to CL-3-12:

[0342]

[0343]

[0344] In a particularly preferred embodiment, the medium according to the invention comprises the compound CL-3-1 or CLP-3-3.

[0345] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of formula VI:

[0346]

[0347] in

[0348] R 61 and R 62represents H, F, straight-chain alkyl or alkoxy groups having 1 to 15 C atoms, straight-chain alkenyl or alkenyloxy groups having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl, alkenyloxy groups each having 3 to 15 C atoms, wherein 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- or -O-CO- is replaced in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen,

[0349] X 61 , X 62 , X 63 , X 64 , X 65 , and X 66 , identically or differently, represents H or F, preferably X 61 , X 62 , X 63 , X 64 , X 65 , and X 66 At least one of them represents F, more preferably X 61 , X 62 , X 63 , X 64 , X 65 , and X 66 At least two of them represent F;

[0350] Z 61 and Z 62 , identically or differently, represent CH2CH2 or a single bond.

[0351] The compound of formula VI is preferably selected from formula VI-1 and VI-2:

[0352]

[0353] The radicals occurring therein have the meanings given for formula VI.

[0354] The compound of formula VI-1 is preferably selected from the formulae VI-1-1 to VI-1-21, very preferably the formula VI-1-4:

[0355]

[0356]

[0357]

[0358] where R 6represents a straight-chain alkyl or alkoxy group having 1 to 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.

[0359] R preferably represents a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, or a pentoxy group.

[0360] In VI-1-22, R 6 Preferably it represents n-propyl.

[0361] In the compounds of formula VI-1-4, (O) preferably represents -O-.

[0362] The compound of formula VI-2 is preferably selected from the formulae VI-2-1 to VI-2-15, very preferably formula VI-2-1:

[0363]

[0364]

[0365]

[0366] where R 6 represents a straight-chain alkyl or alkoxy group having 1 to 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.

[0367] R preferably represents a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, or a pentoxy group.

[0368] In a preferred embodiment of the present invention, the medium additionally comprises one or more compounds of the formulae VII-1 to VII-9

[0369]

[0370]

[0371] in

[0372] R 7 represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, or a straight-chain alkenyl group having 2 to 6 C atoms, and

[0373] w is an integer from 1 to 6.

[0374] Preferably, the medium according to the invention comprises one or more compounds of formula VIII:

[0375]

[0376] in

[0377] R 81 and R 82 , identically or differently, denote H, halogen, CN, SCN, straight-chain alkyl or alkoxy radicals having 1 to 15 C atoms, straight-chain alkenyl or alkenyloxy radicals having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl or alkenyloxy radicals having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, are replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen,

[0378] A 0 , A 81 , and A 82 , each independently of one another denotes phenylene-1,4-diyl, in which one or two CH groups may be replaced by N and one or more H atoms may be replaced by halogen, CN, CH3, CHF2, CH2F, CF3, OCH3, OCHF2 or OCF3, cyclohexane-1,4-diyl, in which one or two non-adjacent CH2 groups may be replaced independently of one another by O and / or S and one or more H atoms may be replaced by F, cyclohexene-1,4-diyl, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl;

[0379] Z 81 and Z 82 , each independently of one another represents -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2H4-, -C2F4, -CF2CH2-, -CH2CF2-, -CFHCFH-, -CFHCH2-, -CH2CFH-, -CF2CFH-, -CFHCF2-, -CH=CH-, -CF=CH-, -CH=CF-, -CF=CF-, -C≡C- or a single bond;

[0380] n represents 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 0 or 1, particularly preferably 0; and

[0381] m represents 0, 1, 2 or 3, preferably 0, 1 or 2, very preferably 1 or 2 and in particular 1.

[0382] In formula I, A 81 and A 82Preference is given to phenylene-1,4-diyl, which may also be mono- or polysubstituted by F, and cyclohexane-1,4-diyl, cyclohexene-1,4-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, very preferably phenylene-1,4-diyl, which may also be mono- or polysubstituted by F, or cyclohexane-1,4-diyl.

[0383] In Formula VIII, Z 81 and Z 82 It preferably represents -CF2O-, -OCF2- or a single bond, very preferably a single bond.

[0384] In formula VIII, A 81 and A 82 Particularly preferred

[0385] wherein L represents halogen, CF3 or CN, preferably F.

[0386] Further preferred are compounds of formula VIII, wherein R 81 and R 82 Each independently of one another represents H, F, or alkyl, alkoxy, alkenyl or alkynyl having 1 to 8, preferably 1 to 5, C atoms, each of which is optionally substituted by halogen, in particular by F.

[0387] R 81 and R 82 Preferably it represents H, optionally fluorinated alkyl or alkoxy having 1 to 7 C atoms, optionally fluorinated alkenyl or alkynyl having 2 to 7 C atoms, optionally fluorinated cycloalkyl having 3 to 12 C atoms.

[0388] Preferably, R 81 and R 82 At least one of them is not H, and R is particularly preferred 81 and R 82 None of them are H. R 81 Very particular preference is given to alkyl. 82 Furthermore, H, alkyl or fluorine are preferred. Very particularly preferably, R 81 is an alkyl group and R 82 R is H or alkyl. 81 , R 82 each independently of one another very particularly preferably represents an unbranched alkyl radical having 1 to 5 C atoms. 81 and R 82 represents a substituted alkyl, alkoxy, alkenyl or alkynyl group, in which the two groups R 81 and R 82 The total number of C atoms in is preferably less than 10.

[0389] Preferred compounds of formula VIII are selected from compounds of formula VIIIa

[0390]

[0391] where R 1 and R 2 , identically or differently, represent straight-chain alkyl radicals having 1 to 15 C atoms, straight-chain alkenyl radicals having 2 to 15 C atoms or branched alkyl or alkenyl radicals having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by substituted, and wherein one or more H atoms may be replaced by fluorine, preferably R 1 and R 2 Both represent straight-chain alkyl groups having 1 to 6 C atoms.

[0392] Very preferred compounds of formula VIIIa are selected from the group consisting of compounds of formulae VIIIa-1 to VIIIa-35:

[0393]

[0394]

[0395]

[0396]

[0397]

[0398]

[0399] Where v is an integer from 1 to 6.

[0400] Further preferred compounds of formula VIII are selected from the following sub-formulae:

[0401]

[0402] where R 81 , R 82 and L have the meanings given above, L preferably represents F, and r, s and t are independently 0, 1, 2, 3, or 4. r is preferably 1 or 2, very preferably 2 and s and t are independently preferably 0 or 1, very preferably 0. R 81 and R 82 In particular, independently represents n-alkyl having 1 to 5 C atoms.

[0403] In a first very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1a to VIII-6a, in particular the compound of formula VIII-3a:

[0404]

[0405] where R 81 , R 82 , r and s have the meanings as defined above.

[0406] In a second very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1b to VIII-6b, in particular the compound of formula I3-b:

[0407]

[0408]

[0409] where R 81 , R 82 , L, r and s have the meanings as defined above.

[0410] In a third very preferred embodiment, the compound of formula VIII-1 to VIII-6 is selected from the compounds of formula VIII-1c to VIII-6c, in particular the compound of formula I3-c:

[0411]

[0412] where R 81 , R 82 , L, r and s have the meanings as defined above.

[0413] In a fourth very preferred embodiment, the compounds of formula VIII-1 to VIII-6 are selected from the compounds of formula VIII-1d to VIII-6d, in particular the compounds of formula VIII-3d

[0414]

[0415] where R 81 , R 82 , L, r and s have the meanings as defined above.

[0416] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from the group consisting of formulae VIII-1a to VIII-6a and one or more compounds selected from the group consisting of formulae VIII-1b to VIII-6b.

[0417] Very particularly preferably, the medium comprises one or more compounds selected from the group of compounds of the formulae VIII-3a, VIII-3b, VIII-3c and VIII-3d:

[0418]

[0419]

[0420] where R 81 , R 82 , L and r have the meanings as defined above and preferably r is 0. Most preferred compounds of formula I include in particular one or more of the following:

[0421]

[0422]

[0423] Alternatively or additionally, compounds of the following formula I may be used:

[0424]

[0425]

[0426]

[0427]

[0428] In a preferred embodiment, the medium comprises one or more compounds of formula IX

[0429]

[0430] in

[0431] R 1 and R 2 , identically or differently, denote H, halogen, straight-chain alkyl or alkoxy radicals having 1 to 15 C atoms, straight-chain alkenyl or alkenyloxy radicals having 2 to 15 C atoms or branched alkyl, alkoxy, alkenyl or alkenyloxy radicals each having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, are replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen,

[0432] L 11 and L 12 , each independently represents F, Cl, CF3 or CHF2,

[0433] L 13 and L 14 , each independently represents H, F, Cl, CF3 or CHF2,

[0434] Y 1represents H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, and

[0435] n is 0 or 1.

[0436] Preferred are LC media comprising compounds of formula IX, wherein n is 0, Y represents H or CH3, more preferably H, and L 11 and L 12 Indicates F.

[0437] Very preferred compounds of formula IX are selected from compounds of formula IX-1 to IX-35

[0438]

[0439]

[0440]

[0441]

[0442]

[0443] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formula X

[0444]

[0445] in

[0446] express

[0447] express

[0448] R X represents a straight-chain or branched alkyl or alkoxy radical having 1 to 15 C atoms, wherein one or more CH2 groups in these radicals may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly bonded to one another, and wherein, in addition, one or more H atoms may be replaced by halogen, preferably by F,

[0449] X X represents F, Cl, CN, SF5, SCN, NCS, a haloalkyl or haloalkoxy group each having 1 to 6 carbon atoms, or a haloalkenyl or haloalkenyloxy group each having 2 to 6 carbon atoms,

[0450] Z XIt represents -C2H4-, -CH2O-, CF2O, -CH=CH- or a single bond.

[0451] In the compound of formula X, R X Preferably denotes alkyl having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms, which is preferably straight-chain.

[0452] In the compound of formula X, X X Preference is given to F, Cl or monofluorinated or polyfluorinated alkyl or alkoxy having 1, 2 or 3 C atoms, or monofluorinated or polyfluorinated alkenyl having 2 or 3 C atoms. X More preferably F, Cl, CF3, CHF2, OCF3, OCHF2, OCFHCF3, OCFHCHF2, OCFHCHF2, OCF2CH3, OCF2CHF2, OCF2CHF2, OCF2CF2CHF2, OCF2CF2CHF2, OCFHCF2CF3, OCFHCF2CHF2, OCF2CF2CF3, OCF2CF2CClF2, OCC1FCF2CF2CF3, OCH═CF2 or CH═CF2, very preferably F or OCF3, furthermore CF3, OCF═CF2, OCHF2 or OCH═CF2, very particularly preferably F, OCF3 or CF3, most preferably F.

[0453] Preferred compounds of formula X are selected from the following sub-formulae:

[0454]

[0455]

[0456] where R X has one of the meanings given in formula X, preferably represents straight-chain alkyl having 1 to 6 C atoms, very preferably ethyl, propyl or butyl, or straight-chain alkenyl having 2 to 6 C atoms, very preferably vinyl or 1-propenyl, most preferably vinyl, and X X has one of the meanings given for formula X and preferably represents F, CF3 or OCF3, very preferably F.

[0457] Very preferred compounds of formula X are selected from the following sub-formulae:

[0458]

[0459]

[0460]

[0461]

[0462]

[0463] Preferably, the LC medium comprises one or more compounds selected from the group consisting of formulae X1-1, X1-3, X2-1 and X2-3.

[0464] Further preferred embodiments are listed below:

[0465] a) a liquid-crystalline medium comprising at least one compound of the formulae Z-1 to Z-8, preferably compounds of the formulae Z-2, Z-4 and Z-6, very preferably compounds of Z-4

[0466]

[0467]

[0468] where R Z With the above R 2A , preferably denotes an alkyl group having 1 to 7 C atoms or an alkenyl group having 2 to 7 C atoms,

[0469] (O) represents O or a single bond, and alkyl represents an alkyl group having 1 to 7 C atoms.

[0470] b) Preferred liquid-crystalline media according to the invention comprise one or more substances containing tetrahydronaphthyl or naphthyl units, for example compounds of the formulae N-1 to N-5,

[0471]

[0472]

[0473] where R 1N and R 2N Each independently has a 2A The indicated meanings preferably represent straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, and

[0474] Z 1 and Z 2 Each independently represents -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.

[0475] c) preferably a mixture comprising one or more compounds selected from the group consisting of difluorodibenzochroman compounds of formula BC, chromans of formula CR, and fluorophenanthrenes of formulae PH-1 and PH-2,

[0476]

[0477] where R B1 , R B2 , R CR1 , R CR2 , R P1 , R P2 Each independently of the other has R of formula III 31 , preferably alkyl or alkoxy with 1 to 6 C atoms, and

[0478] c is 0, 1 or 2.

[0479] Particularly preferred compounds of formula BC, CR and PH-1 are compounds BC-1 to BC-7, CR-1 to CR-5, and BP-1 to BP-7

[0480]

[0481]

[0482]

[0483] in

[0484] Alkyl and alkyl* each independently of one another denote a straight-chain alkyl radical having 1 to 6 C atoms, and

[0485] Alkenyl and alkenyl* each independently of one another represent straight-chain alkenyl having 2 to 6 C atoms.

[0486] More preferred are mixtures comprising one, two or three of the formulae BC-2, BC-3, BP-2 and / or BP-3, very preferably BP-2 and / or BP-3, in particular BP-3.

[0487] d) Preferred mixtures comprise one or more indane compounds of the formula In,

[0488]

[0489] in

[0490] R 11 , R 12 , and R 13 each independently of one another represents a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl radical having 1 to 6 C atoms,

[0491] R 12 and R 13 Alternatively represents halogen, preferably F,

[0492] express

[0493]

[0494] i represents 0, 1 or 2.

[0495] Preferred compounds of formula In are compounds of formula In-1 to In-16 described below:

[0496]

[0497]

[0498] Particularly preferred are compounds of the formulae In-1, In-2, In-3 and In-4.

[0499] e) Preferred mixtures additionally contain one or more compounds of the formulae L-1 to L-5,

[0500]

[0501]

[0502] in

[0503] R, R 1 and R 2 Each independently has the above R 2A The above meanings and alkyl represent an alkyl radical having 1 to 6 C atoms. The parameter s represents 1 or 2.

[0504] The compounds of the formulae L-1 to L-9 are preferably used in a concentration of 5 to 15% by weight, in particular 5 to 12% by weight and very particularly preferably 8 to 10% by weight.

[0505] f) Preferred mixtures additionally contain one or more compounds of the formula IIA-Y

[0506]

[0507] where R 11 and R 12 With the above formula IIA for R 2A One of the meanings given, and L 1 and L 2 , identically or differently represent F or Cl,

[0508] Preferred compounds of formula IIA-Y are selected from the following sub-formulas

[0509]

[0510]

[0511] wherein Alkyl and Alkyl* each independently represent a straight-chain alkyl group having 1 to 6 carbon atoms, Alkoxy represents a straight-chain alkoxy group having 1 to 6 carbon atoms, Alkenyl and Alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 carbon 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-.

[0512] Particularly preferred compounds of formula IIA-Y are selected from the following sub-formulae:

[0513]

[0514] Here, Alkoxy and Alkoxy* have the meanings defined above and preferably denote methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy, very preferably both butoxy.

[0515] Preferably, the medium according to the invention comprises a compound selected from the group consisting of compounds of formulae S-1 to S-15:

[0516]

[0517] Where n = 0 or 1

[0518]

[0519] wherein n=1, 2, 3, 4, 5, 6 or 7, preferably n=1 or 7, very preferably 7,

[0520]

[0521]

[0522]

[0523] in

[0524] R ST represents H, alkyl or alkoxy radicals having 1 to 15 C atoms, wherein, in addition, one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O-, -O-CO- are substituted in such a way that the O atoms are not directly bonded to one another, and wherein, in addition, one or more H atoms may be replaced by halogen,

[0525] Each time it appears, the same or different, it means

[0526] p represents 0, 1 or 2,

[0527] q represents 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0528] The compounds of the formulae S-1 to S-15 are preferably each present in the liquid-crystal mixture according to the invention in an amount of 0.005 to 0.5%, based on the mixture.

[0529] If the mixtures according to the invention comprise two or more compounds from the group consisting of compounds S-1 to S-15, the concentration is correspondingly increased to 0.01-1% in the case of two compounds, based on the mixture.

[0530] However, the total proportion of compounds of the formulae ST and S-1 to S-15, based on the mixture according to the invention, should not exceed 2%.

[0531] The liquid crystal media according to the invention (also referred to herein as liquid crystal host mixtures) are suitable for use in polymer-stabilized displays. To this end, the media according to the invention optionally comprise one or more polymerizable compounds of formula P:

[0532] P-Sp-A 1 -(Z 1 -A 2 ) z -RP

[0533] which are independent of each other and appear the same or differently each time

[0534] P represents a polymerizable group,

[0535] Sp represents a spacer group or a single bond,

[0536] A 1 、A 2 represents an aromatic, heteroaromatic, alicyclic 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,

[0537] Z 1Represents -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 single key,

[0538] R 0 , R 00 represents H or an alkyl group having 1 to 12 C atoms,

[0539] R represents H, L, or P-Sp-,

[0540] L represents F, Cl, -CN, P-Sp- or a straight-chain, branched or cycloalkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl,

[0541] z is 0, 1, 2, or 3, and

[0542] n1 is 1, 2, 3, or 4.

[0543] As used herein, the term "reliability" refers to the quality of a display's performance over time and under various stresses, such as light load, temperature, humidity, and voltage. It also includes display effects such as image sticking (area and line), mura, smearing, and the like, 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 often used. This is a measure of the ability to maintain a constant voltage in a test display. Among other factors, a high VHR is a prerequisite for high reliability of LC media.

[0544] Unless otherwise stated, the term "PSA" is used hereinafter when referring generally to polymer maintained alignment type displays, and the term "PS" is used when referring to specific display modes such as PS-VA, PS-TN, etc.

[0545] As used herein, the terms "active layer" and "switchable layer" refer to a layer in an electro-optical display, e.g. an LC display, comprising one or more molecules with structural and optical anisotropy (e.g. 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 unpolarized light.

[0546] As used herein, the terms "tilt" and "tilt angle" are understood to denote the tilted alignment of the LC molecules of an LC medium relative to the cell surface in an LC display (preferably a PSA display). The tilt angle here denotes the average angle (<90°) between the longitudinal molecular axis of the LC molecules (LC director) and the plane-parallel outer plates forming the LC cell. Low values ​​for the tilt angle (i.e., large deviations from a 90° angle) correspond to large tilts. A suitable method for measuring the tilt angle is given in the Examples. Unless otherwise stated, the tilt angle values ​​disclosed above and below relate to this measurement method.

[0547] As used herein, the terms "reactive mesogen" and "RM" are understood to mean a compound comprising a mesogenic or liquid crystal backbone and attached thereto one or more functional groups suitable for polymerization, and said functional groups are also referred to as "polymerizable groups" or "P".

[0548] Unless otherwise indicated, the term "polymerizable compound" as used herein is to be understood as a polymerizable monomeric compound.

[0549] As used herein, the term "low molecular weight compound" is understood to mean a compound that is monomeric and / or not prepared by polymerization, as opposed to a "polymeric compound" or "polymer."

[0550] As used herein, the term "non-polymerizable compound" is understood to mean a compound that does not comprise functional groups suitable for polymerization under the conditions typically applied to the polymerization of RMs.

[0551] As used herein, the term "mesogenic group" is known to those skilled in the art and is described in the literature and refers to a group that, due to the anisotropy of its attractive and repulsive interactions, substantially contributes to the production of liquid crystal (LC) phases in low molecular weight or polymeric substances. A compound comprising a mesogenic group (mesogenic compound) does not necessarily have to have an LC phase itself. A mesogenic compound may also exhibit LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod-shaped or disc-shaped units. An overview of terms and definitions used in connection with mesogenic or LC compounds is given in Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368.

[0552] As used herein, the terms "optically active" and "chiral" are synonymous for materials that can induce a helical pitch in a nematic host material, also referred to as "chiral dopants."

[0553] As used herein, the term "spacer" (also referred to above and below as "Sp") is known to those skilled in the art in the art and is 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" or "spacer group" refers to a flexible group, for example an alkylene group, which connects the mesogenic group and the polymerizable group(s) in the polymerizable mesogenic compound.

[0554] Likewise, in the compounds of Formulas Ia and Ib, a spacer group connects the central hydrocarbon group to the optically active, stable hindered amine functionality.

[0555] In context, represents a trans-1,4-cyclohexylene ring.

[0556] In the group In , a single bond shown between two ring atoms can be attached to any free position of the benzene ring.

[0557] "Organic group" in this context means a carbon or hydrocarbon group.

[0558] "Carbon group" means a monovalent or polyvalent organic group containing at least one carbon atom, wherein 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 "hydrocarbyl group" means 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.

[0559] "Halogen" means F, Cl, Br or I, preferably F or Cl.

[0560] -CO-, -C(=O)- and -C(O)- represent carbonyl groups, i.e.

[0561] The carbon or hydrocarbyl group can be a saturated or unsaturated group. Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. Carbon or hydrocarbyl groups having more than 3 C atoms can be straight chain, branched and / or cyclic and can also contain spiro connections or fused rings.

[0562] The terms "alkyl," "aryl," "heteroaryl," and the like also include polyvalent groups such as alkylene, arylene, heteroarylene, and the like.

[0563] The term "aryl" refers to an aromatic carbon group or a group derived therefrom. The term "heteroaryl" refers to an "aryl" as defined above containing one or more heteroatoms (preferably selected from N, O, S, Se, Te, Si and Ge).

[0564] Preferred carbon and hydrocarbon radicals are optionally substituted, linear, branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy radicals having 1 to 40, preferably 1 to 20, very preferably 1 to 12 C atoms, optionally substituted aryl or aryloxy radicals having 5 to 30, preferably 6 to 25 C atoms, or optionally substituted alkylaryl, aralkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy radicals having 5 to 30, preferably 6 to 25 C atoms, where one or more C atoms may also be replaced by heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.

[0565] Further preferred carbon and hydrocarbyl groups are C1-C 20 Alkyl, C2-C 20 Alkenyl, C2-C 20 Alkynyl, C3-C 20 Allyl, C4-C 20 Alkyldiene, C4-C 20 Polyene, C6-C 20Cycloalkyl, C4-C 15 Cycloalkenyl, C6-C 30 Aryl, C6-C 30 Alkyl aryl, C6-C 30 Aralkyl, C6-C 30 Alkyl aryloxy, C6-C 30 Arylalkoxy, C2-C 30 Heteroaryl, C2-C 30 Heteroaryloxy.

[0566] Particularly preferred is C1-C 12 Alkyl, C2-C 12 Alkenyl, C2-C 12 Alkynyl, C6-C 25 Aryl and C2-C 25 Heteroaryl.

[0567] Further preferred carbon and hydrocarbon radicals are straight-chain, branched or cyclic alkyl radicals having 1 to 20, preferably 1 to 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 be replaced independently of one another 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 the O and / or S atoms are not directly connected to each other.

[0568] R x Preferably it represents H, F, Cl, CN, a linear, branched or cyclic alkyl chain having 1 to 25 C atoms, in which, in addition, one or more non-adjacent C atoms may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, and in which one or more H atoms may be replaced by F or Cl, or 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.

[0569] 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, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, and the like.

[0570] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl and the like.

[0571] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl and the like.

[0572] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, 2-methylbutoxy, n-pentoxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, and the like.

[0573] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino and the like.

[0574] Aryl and heteroaryl groups may be monocyclic or polycyclic, i.e. they may contain one ring (e.g. phenyl) or two or more rings, which may also be fused (e.g. naphthyl) or covalently bonded (e.g. biphenyl), or a combination of fused and linked rings. Heteroaryl groups contain one or more heteroatoms, preferably selected from O, N, S and Se.

[0575] Particularly preferred are mono-, bi- or tricyclic aryl radicals having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl radicals having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6- or 7-membered aryl and heteroaryl radicals, in which one or more CH groups may additionally be replaced by N, S or O in such a way that the O atoms and / or S atoms are not directly connected to one another.

[0576] 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, Perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, and the like.

[0577] 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, indole azine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthimidazole, pyridimidazole, pyrazinimidazole, quinoxalinoimidazole, benzoxazole, naphthimidazole, anthraxazole, phenanthimidazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo- 7,8-quinoline, benzisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiophene, benzothiadiazolethiophene, or a combination of these groups.

[0578] The aryl and heteroaryl groups mentioned above and below may also be substituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or other aryl or heteroaryl groups.

[0579] (Non-aromatic) alicyclic and heterocyclic groups include both saturated rings, i.e. rings containing only single bonds, and partially unsaturated rings, i.e. those which may also contain multiple bonds. The heterocyclic ring contains one or more heteroatoms, preferably selected from Si, O, N, S and Se.

[0580] (Non-aromatic) alicyclic groups and heterocyclic groups can be monocyclic, i.e. only contain one ring (e.g. cyclohexane), or polycyclic, i.e. contain multiple rings (e.g. decalin or bicyclooctane). Particularly preferred are saturated groups. In addition, preferably there is a single-, double- or tricyclic group of 5-25 annular atoms, which optionally contains a fused ring and is optionally substituted. Further preferred are 5-, 6-, 7- or 8-membered carbocyclic groups, wherein in addition, one or more C atoms may be substituted by Si and / or one or more CH groups may be substituted by N and / or one or more non-adjacent CH2 groups may be substituted by-O- and / or-S-.

[0581] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups such as cyclopentane, tetrahydrofuran, tetrahydrothiophene, pyrrolidine; 6-membered groups such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine; 7-membered groups such as cycloheptane; and condensed groups such as tetralin, decalin, indane, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindan-2,5-diyl.

[0582] Preferred substituents are, for example, solubility-promoting groups, such as alkyl or alkoxy groups; electron-withdrawing groups, such as fluorine, nitro or nitrile; or substituents for increasing the glass transition temperature (Tg) of the polymer, particularly bulky groups, such as tert-butyl or optionally substituted aryl groups.

[0583] Preferred substituents, hereinafter also referred to as "L S ”, such as 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, a linear or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group each having 1 to 25 C atoms, in which one or more H atoms may be optionally replaced by F or Cl, an optionally substituted silyl group having 1 to 20 Si atoms, or an optionally substituted aryl group having 6 to 25, preferably 6 to 15, C atoms.

[0584] where R x represents H, F, Cl, CN, or a straight-chain, branched or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2- groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S- atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by F, Cl, P- or P-Sp-, and

[0585] Y 1 Represents halogen.

[0586] "Substituted silyl or aryl" preferably means substituted with halogen, -CN, R 0 、-OR 0 、-CO-R 0 、-CO-OR 0、-O-CO-R 0 OR-O-CO-OR 0 Substituted, where R 0 represents H or an alkyl group having 1 to 20 C atoms.

[0587] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 and, furthermore, phenyl.

[0588] A 1 and A 2 Very preferred wherein L has one of the above meanings and r represents 0, 1, 2, 3 or 4, in particular express

[0589] The polymerizable group P is a group suitable for polymerization reactions (e.g., free radical or ionic chain polymerization, addition polymerization, or condensation polymerization), or a group suitable for polymer-analogous reactions (e.g., addition or condensation on the polymer backbone). Particularly preferred are groups suitable for chain polymerization, in particular those containing a C═C double bond or a —C≡C— triple bond, and groups suitable for ring-opening polymerization, such as oxetane or epoxy groups.

[0590] 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 W 3 -NH-、CH2=CW1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -、CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 、W 5 and W 6 each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 Each independently 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.

[0591] 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-, Phe-CH=CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 、W 5 and W 6 each independently represents Cl, an oxaalkyl or oxacarbonylalkyl group having 1 to 5 C atoms, W 7 and W 8 Each independently represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 represents an integer of 1 to 10.

[0592] Very particularly preferred groups P are selected from the group consisting of: CH2=CW 1 -CO-O-, in particular CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, also CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-,

[0593] Other preferred polymerizable groups P are selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy groups, most preferably from acrylate and methacrylate groups.

[0594] If the spacer group Sp is different from a single bond, it is preferably of the formula Sp"-X", so that each group P-Sp- corresponds to the formula R-Sp"-X"-, where

[0595] Sp" denotes a straight-chain or branched alkylene radical having 1 to 20, preferably 1 to 12, C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and wherein, in addition, one or more non-adjacent CH2 groups may each be replaced independently of one another 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,

[0596] X" means -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,

[0597] R 0 and R 00 each independently of one another represents H or an alkyl group having 1 to 20 C atoms, and

[0598] Y 2 and Y 3 Each independently represents H, F, Cl or CN.

[0599] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 00 - or single key.

[0600] 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 -, wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 0 and R 00 has the meaning indicated above.

[0601] Particularly preferred groups Sp and -Sp"-X"- are -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, wherein p1 and q1 have the meanings indicated above.

[0602] Particularly preferred radicals Sp" are in each case linear ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, vinylene, propenylene and butenylene.

[0603] In a preferred embodiment of the present invention, the compounds of formula P and its subformulae 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 is ≥2 (branched polymerizable group).

[0604] Preferred compounds of formula P according to this preferred embodiment are those wherein 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 group consisting of:

[0605] -X-alkyl-CHPP S1

[0606] -X-alkyl-CH((CH2) aa P)((CH2) bb P) S2

[0607] -XN((CH2) aa P)((CH2) bb P) S3

[0608] -X-alkyl-CHP-CH2-CH2P S4

[0609] -X-alkyl-C(CH2P)(CH2P)-C aa H 2aa+1S5

[0610] -X-alkyl-CHP-CH2P S6

[0611] -X-alkyl-CPP-C aa H 2aa+1 S7

[0612] -X-alkyl-CHPCHP-C aa H 2aa+1 S8

[0613] wherein P is as defined in formula P,

[0614] Alkyl represents a single bond or a straight-chain or branched alkylene radical having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN, and in which one or more non-adjacent CH2 groups may each independently of one another be substituted by -C(R 0 )=C(R 0 )-、-C≡C-、-N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- substitution, where R 0 has the meaning indicated above,

[0615] aa and bb each independently represent 0, 1, 2, 3, 4, 5 or 6,

[0616] X has one of the meanings indicated for X", and is preferably O, CO, SO2, O-CO-, CO-O or a single bond.

[0617] Preferred spacer groups Sp(P)2 are selected from formulae S1, S2 and S3.

[0618] Very preferred spacer groups Sp(P)2 are selected from the following sub-formulas:

[0619] -CHPP S1a

[0620] -O-CHPP S1b

[0621] -CH2-CHPP S1c

[0622] -OCH2-CHPP S1d

[0623] -CH(CH2-P)(CH2-P) S2a

[0624] -OCH(CH2-P)(CH2-P) S2b

[0625] -CH2-CH(CH2-P)(CH2-P) S2c

[0626] -OCH2-CH(CH2-P)(CH2-P) S2d

[0627] -CO-NH((CH2)2P)((CH2)2P) S3a

[0628] In the compounds of formula P and subformulae thereof as described above and below, P is preferably selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably from acrylate and methacrylate.

[0629] More preferred are compounds of the formula P and its subformulae as described above and below, wherein all polymerizable groups P present in the compound have the same meaning and very preferably denote acrylate or methacrylate, most preferably methacrylate.

[0630] In the compounds of formula P and subformulae thereof as described above and below, R preferably represents P-Sp-.

[0631] More preferred are compounds of formula P and its subformulae as described above and below, wherein Sp represents a single bond or -(CH2) p1 -、-O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , wherein 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 CO-group, respectively, is attached to the benzene ring.

[0632] More preferred are compounds of formula P and its subformulae as described above and below, wherein at least one group Sp is a single bond.

[0633] More preferred are compounds of formula P and its subformulae as described above and below, wherein 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 , wherein 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 CO-group, respectively, is attached to the benzene ring.

[0634] Very preferred group -A in formula P 1 -(ZA 2 ) z -Selected from the following formula

[0635]

[0636] wherein at least one phenyl ring is substituted by at least one group L and the phenyl ring is optionally further substituted by one or more groups L or P-Sp-.

[0637] Preferred compounds of formula P and its subformulae are selected from the following preferred embodiments, including any combination thereof:

[0638] - all groups P in the compound have the same meaning,

[0639] --A 1 -(ZA 2 ) z - is selected from the group consisting of formulae A1, A2 and A5,

[0640] - the compound contains exactly two polymerizable groups (represented by the group P),

[0641] - the compound contains exactly three polymerizable groups (represented by the group P),

[0642] -P is selected from the group consisting of acrylates, methacrylates and oxetanes, very preferably acrylates or methacrylates,

[0643] -P is methacrylate,

[0644] - all groups Sp are single bonds,

[0645] - 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,

[0646] -Sp, when different from a single bond, is -(CH2) p2 -、-(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O atom or CO- group is attached to the benzene ring,

[0647] -Sp is a single bond or represents -(CH2) p2 -、-(CH2) p2 -O-, -(CH2) p2-CO-O-, -(CH2) p2 -O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O atom or CO- group is attached to the benzene ring,

[0648] -R means P-Sp-,

[0649] -R does not represent or contain a polymerizable group,

[0650] -R does not represent or contain a polymerizable group and represents a linear, branched or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2 groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, and wherein one or more H atoms are each optionally replaced by F, Cl or L a Alternative,

[0651] -L or L' represents F, Cl or CN,

[0652] -L is F.

[0653] Suitable and preferred compounds of formula P are selected from the following:

[0654]

[0655]

[0656]

[0657]

[0658]

[0659] Wherein, each group has the following meaning:

[0660] P 1 、P 2 and P 3 each independently of one another represents an acrylate group or a methacrylate group,

[0661] 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 given above and below for Sp), and particularly preferably represents -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO- or -(CH2) p1-O-CO-O-, wherein p1 is an integer from 1 to 12, and wherein the group P 1 -Sp 1 -、P 2 -Sp 2 - and P 3 -Sp 3 - One or more of them can represent R aa , provided that there is a group P 1 -Sp 1 -、P 2 -Sp 2 - and P 3 -Sp 3 - at least one of them is different from R aa ,

[0662] R aa represents H, F, Cl, CN or a straight-chain or branched alkyl radical having 1 to 25 C atoms, wherein one or more non-adjacent CH2 groups may also be replaced independently of one another 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 the 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 - instead, particularly preferably a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms, where alkenyl and alkynyl have at least two C atoms and branched radicals have at least three C atoms,

[0663] R 0 、R 00 each independently of one another and identically or differently on each occurrence represents H or alkyl having 1 to 12 C atoms,

[0664] R y and R z Each independently represents H, F, CH3 or CF3,

[0665] X 1 、X 2 and X 3 each independently represents -CO-O-, -O-CO- or a single bond,

[0666] Z 1 Indicates -O-, -CO-, -C(R y Rz )- or -CF2CF2-,

[0667] Z 2 and Z 3 Each independently represents -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3 or 4,

[0668] L, on each occurrence, identically or differently, represents F, Cl, CN or linear or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, preferably F,

[0669] L' and L" each independently represent H, F or Cl,

[0670] k represents 0 or 1,

[0671] r represents 0, 1, 2, 3 or 4,

[0672] s represents 0, 1, 2 or 3,

[0673] t represents 0, 1 or 2,

[0674] x represents 0 or 1.

[0675] Particularly preferred are compounds of the formulae P2, P13, P17, P22, P23, P24, P30, P31 and P32.

[0676] Further preferred are the three reactive compounds P15 to P30, in particular P17, P18, P19, P22, P23, P24, P25, P26, P30, P31 and P32.

[0677] In the compounds of formulae P1 to P32, the group Preferred

[0678] wherein L has, identically or differently on each occurrence, 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 and in particular F or CH3.

[0679] Very particularly preferred compounds of the formula P are selected from Table E below.

[0680] To produce PSA displays, the polymerisable compounds contained in the LC medium are polymerised or crosslinked (if one compound contains two or more polymerisable groups) by polymerisation in situ in the LC medium (between the substrates of the LC display), optionally while applying a voltage to the electrodes.

[0681] The structure of the PSA display according to the invention corresponds to the typical geometry of PSA displays, as described in the prior art cited at the outset. Geometries without protrusions are preferred, particularly those in which the electrodes on the color filter side are unstructured and only the electrodes on the TFT side have slots. A particularly suitable and preferred electrode structure for PS-VA displays is described, for example, in US 2006 / 0066793 A1.

[0682] A preferred PSA-type LC display according to the invention comprises:

[0683] a first substrate comprising a pixel electrode defining a pixel area (the pixel electrode being connected to a switching element arranged in each pixel area and optionally comprising a micro-slit pattern), and optionally a first alignment layer arranged on the pixel electrode,

[0684] a second substrate comprising a common electrode layer (which may be arranged on the entire portion of the second substrate facing the first substrate), and optionally a second alignment layer,

[0685] - an LC layer disposed between the first substrate and the second substrate and comprising an LC medium comprising a polymerizable component and a liquid crystal host, the polymerizable component comprising one or more compounds of formula R, the liquid crystal host comprising as described above and below, wherein the polymerizable component may also be polymerized.

[0686] The first and / or second alignment layers control the alignment direction of the LC molecules in the LC layer. For example, in a PS-VA display, the alignment layer is selected to impart homeotropic (or vertical) alignment (i.e., perpendicular to the surface) or tilted alignment to the LC molecules. Such alignment layers may comprise, for example, polyimide, which may also be rubbed or prepared using photoalignment methods.

[0687] The LC layer containing the LC medium can be deposited between the substrates of the display by methods conventionally used by display manufacturers, such as the so-called drop fill (ODF) method. The polymerizable components of the LC medium are then polymerized, for example, by UV photopolymerization. This polymerization can be carried out in one step or in two or more steps.

[0688] A PSA display may comprise further elements such as colour filters, a black matrix, a passivation layer, an optical retardation layer, transistor elements for addressing the individual pixels etc., all of which are well known to those skilled in the art and may be used without inventive skill.

[0689] Those skilled in the art can design the electrode structure depending on the type of individual display. For example, for PS-VA displays, multi-domain orientation of LC molecules can be induced by providing electrodes with slits and / or bumps or protrusions to produce two, four or more differently tilted alignment directions.

[0690] After polymerization, the polymerizable compound forms a cross-linked polymer that causes a certain pre-tilt of the LC molecules in the LC medium. Without wishing to be bound by a particular theory, it is believed that at least a portion of the cross-linked polymer formed by the polymerizable compound phase separates or precipitates from the LC medium and forms a polymer layer on the substrate or electrode, or on an alignment layer provided thereon. Microscopic measurements (e.g., SEM and AFM) have confirmed that at least a portion of the formed polymer accumulates at the LC / substrate interface.

[0691] The polymerization can be carried out in one step. It is also possible to first carry out the polymerization in a first step (optionally while applying a voltage) in order to produce a pretilt angle, and then polymerize or crosslink the compounds that did not react in the first step in a second polymerization step without applying a voltage ("final curing").

[0692] Suitable and preferred polymerization methods are, for example, thermal or photopolymerization, preferably photopolymerization, in particular UV-induced photopolymerization, which can be achieved by exposing the polymerizable compound to UV radiation.

[0693] Optionally, one or more polymerization initiators are added to the LC medium. Suitable conditions for polymerization and suitable types and amounts of initiators are known to those skilled in the art and are described in the literature. Suitable for free-radical polymerization are, for example, commercially available photoinitiators or (Ciba AG). If a polymerization initiator is used, its proportion is preferably from 0.001 to 5% by weight, particularly preferably from 0.001 to 1% by weight.

[0694] The polymerizable compounds according to the invention are also suitable for initiator-free polymerization, which is accompanied by considerable advantages, such as lower material costs and, in particular, less contamination of the LC medium by possible residual amounts of initiator or its degradation products. The polymerization can thus also be carried out without the addition of initiators. In a preferred embodiment, the LC medium therefore contains no polymerization initiator.

[0695] The LC medium may also contain one or more stabilizers in order to prevent undesired spontaneous polymerization of the RMs, for example during storage or transport. Suitable types and amounts of stabilizers are known to those skilled in the art and are described in the literature. Particularly suitable are, for example, the stabilizers commercially available from series (Ciba AG), such as 1076. If stabilizers are used, their proportion is preferably 10 to 500,000 ppm, particularly preferably 50 to 50,000 ppm, based on the total amount of RM or polymerizable component (component P).

[0696] The polymerizable compounds of formula P do in particular show good UV absorption and are therefore particularly suitable for use in a process for the production of PSA displays comprising one or more of the following features:

[0697] - the polymerizable medium in the display is exposed to UV light in a 2-step process comprising a first UV exposure step ("UV-1 step") to create the tilt angle, and a second UV exposure step ("UV-2 step") to complete the polymerization,

[0698] The polymerizable medium is exposed to UV light generated by energy-saving UV lamps (also called "green UV lamps") in the display. These lamps are characterized by relatively low intensities in their absorption spectrum between 300 and 380 nm (1 / 100 to 1 / 10 of conventional UV1 lamps) and are preferably used in the UV2 step, but can also be used optionally in the UV1 step when avoiding high intensities is necessary for the process.

[0699] - In the display the polymerizable medium is exposed to UV light generated by a UV lamp having a radiation spectrum shifted to longer wavelengths (preferably 340 nm or longer) in order to avoid the short UV light exposure in the PS-VA process.

[0700] Both low intensity and UV shifted to longer wavelengths are used to protect the organic layers from damage that can be caused by UV light.

[0701] A preferred embodiment of the present invention relates to a process for producing a PSA display as described above and below, comprising one or more of the following features:

[0702] - the polymerisable LC medium is exposed to UV light in a 2-step process comprising a first UV exposure step ("UV-1 step") to produce the tilt angle and a second UV exposure step ("UV-2 step") to complete the polymerisation,

[0703] The polymerizable LC medium was exposed to UV light with a power of 0.5 mW / cm 2 Up to 10mW / cm 2UV light in the wavelength range of 300-380 nm of an intensity of 100 nm, preferably for the UV2 step, and optionally also for the UV1 step,

[0704] - the polymerisable LC medium is exposed to UV light having a wavelength of 340 nm or longer, and preferably 400 nm or shorter.

[0705] This preferred method is performed, for example, using a desired UV lamp, or using a bandpass filter and / or a cutoff filter that is substantially transmissive to UV light having the desired wavelength and substantially blocks UV light having the undesired wavelength. For example, when UV light having a wavelength λ of 300-400 nm is desired, UV exposure can be performed using a wide bandpass filter that is substantially transmissive to wavelengths in the range of 300 nm < λ < 400 nm. When UV light having a wavelength λ greater than 340 nm is desired, UV exposure can be performed using a cutoff filter that is substantially transmissive to wavelengths in the range of λ > 340 nm.

[0706] "Substantially transmit" means that the filter transmits a majority, preferably at least 50%, of the intensity of incident light of a desired wavelength. "Substantially block" means that the filter does not transmit a majority, preferably at least 50%, of the intensity of incident light of an undesired wavelength. "Desired (undesired) wavelength" means, for example, wavelengths within (outside) a given λ range in the case of a bandpass filter, and wavelengths above (below) a given λ value in the case of a cutoff filter.

[0707] This preferred method makes it possible to manufacture displays by using longer UV wavelengths, thereby reducing or even avoiding the harmful and damaging effects of the short UV light component.

[0708] The UV radiation energy is generally between 6 and 100 J, depending on the production process conditions.

[0709] Preferably, the LC medium according to the present invention consists essentially of a polymerizable component P) comprising one or more polymerizable compounds of formula P and an LC host mixture as described above and below, and an optically active component comprising one or more chiral dopants. However, the LC medium may additionally comprise one or more other components or additives, preferably selected from the list including, but not limited to, comonomers, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, hydrophobic agents, binders, flow improvers, defoamers, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0710] Particular preference is given to LC media which comprise one, two or three polymerisable compounds of the formula P.

[0711] Preferably, the proportion of the compound of the formula P in the LC medium is >0 to <5%, very preferably >0 to <1%, most preferably 0.01 to 0.5%.

[0712] In a preferred embodiment, the medium according to the invention preferably contains one or more compounds of formula S in a total concentration range of 10 ppm to 2000 ppm, more preferably 100 ppm to 1000 ppm, still more preferably 150 ppm to 500 ppm, very preferably 200 ppm to 400 ppm and in particular 250 to 300 ppm.

[0713] The medium according to the invention preferably has negative dielectric anisotropy.

[0714] The liquid-crystal mixtures according to the invention are nematic, preferably at temperatures of -20°C or below, preferably at -30°C or below, very preferably at -40°C or below.

[0715] For the liquid-crystalline media according to the invention, it is advantageous to have a nematic phase which preferably has a temperature range from ≤-20°C to ≥70°C, particularly preferably from ≤-30°C to ≥80°C and very particularly preferably from ≤-40°C to ≥80°C.

[0716] The expression "having a nematic phase" here means, on the one hand, that at low temperatures no smectic phase and no crystallization is observed at the corresponding temperature and, on the other hand, that no clearing (phase transition to the isotropic phase) occurs when heating from the nematic phase. The low-temperature investigations are carried out in a flow viscometer at the corresponding temperature and are checked by storage for at least 100 hours in a test cell having a layer thickness corresponding to the electro-optical application. If the storage stability in the corresponding test cell at a temperature of -20°C is 1000 hours or more, the medium is said to be stable at this temperature. At 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.

[0717] In a preferred embodiment, the medium according to the invention has a clearing temperature of 75° C. or higher, preferably 80° C. or higher, more preferably 82° C. or higher and in particular 83° C. or higher.

[0718] In a preferred embodiment, the dielectric anisotropy Δε of the liquid-crystal mixture according to the invention is from -2.0 to -6.0, more preferably from -2.2 to -5.0, very preferably from -2.4 to -4.3 and in particular from -3.0 to -4.0.

[0719] The rotational viscosity γ1 at 20° C. is preferably in the range of 50 to 250 mPas, more preferably in the range of 70 to 140 mPas.

[0720] The medium according to the present invention preferably comprises

[0721] - one or more compounds of the formula ST in a total concentration range of 1 ppm to 2000 ppm, more preferably 50 ppm to 1500 ppm, still more preferably 150 ppm to 900 ppm, very preferably 200 ppm to 700 ppm and in particular 250 ppm to 550 ppm;

[0722] one or more compounds of the formula Ia in a total concentration range of 1 ppm to 500 ppm, more preferably 10 ppm to 400 ppm, still more preferably 20 ppm to 300 ppm, very preferably 50 ppm to 200 ppm and in particular 70 ppm to 130 ppm;

[0723] one or more compounds of the formula Ib in a total concentration range of 1 ppm to 1000 ppm, more preferably 10 ppm to 800 ppm, still more preferably 50 ppm to 750 ppm, very preferably 70 ppm to 500 ppm and in particular 80 ppm to 350 ppm.

[0724] Further preferred embodiments, alone or in combination with one another, are as follows.

[0725] The medium preferably comprises:

[0726] one or more compounds of the formula IIA, preferably IIA-10 and optionally IIA-2, more preferably one or more compounds CCY-n-Om, in particular CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably in a total concentration range of 2% to 35%, more preferably 5% to 30%, particularly preferably 7% to 28%;

[0727] - one or more compounds of the formula IIA-10, more preferably one or more compounds CCY-n-Om, in particular CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably in a total concentration range of 2% to 25%, more preferably 5% to 20%, particularly preferably 7% to 18%;

[0728] - one or more compounds of formula IIA-Y, preferably in a total concentration range of 1% to 15%, more preferably 2% to 12%, very preferably 3% to 10%;

[0729] one or more compounds of the formula IID, preferably selected from the group consisting of compounds of the formulae IID-4 and IID-10, more preferably IID-4, very preferably CLY-n-Om, in particular CLY-2-O4, CLY-3-O2 and / or CLY-3-O3, preferably in a total concentration ranging from 2% to 42%, more preferably from 15% to 37%, particularly preferably from 20% to 35%,

[0730] and / or

[0731] - one or more compounds of the formula IID-10, preferably CLOY-n-Om, in particular CLOY-3-O2, preferably in a total concentration range of 2% to 35%, more preferably 4% to 30%, particularly preferably 6% to 26%;

[0732] and / or

[0733] - one or more compounds of formula III, preferably formula III-2 and / or III-3, more preferably formula III-2-6 and / or III-3, in particular one or more compounds B(S)-nO-Om and / or COB(S)-n-Om, very particularly B(S)-2O-O4, B(S)-2O-O5, B(S)-2O-O6, B(S)-2O-O1(c5), B(S)-4O-O1(c5), and / or COB(S)-2-O4, preferably in a total concentration range of 1% to 15%, more preferably 2% to 12% and very preferably 3% to 10%;

[0734] and / or

[0735] - one or more compounds of formula III and / or PH-1, preferably formula III-2 and / or BP-3, more preferably formula III-2-6, in particular selected from B(S)-2O-O4, B(S)-2O-O5 and B(S)-2O-O6, preferably in a total concentration range of 1% to 15%, more preferably 2% to 12% and very preferably 3% to 10%;

[0736] VI

[0737] and / or

[0738] - one or more compounds of formula IV, preferably in a total concentration range of 25% to 70%, more preferably 30% to 60%, particularly preferably 40% to 55%;

[0739] and / or

[0740] - one or more compounds of formula IV-1, preferably IV-1-6, preferably in a total concentration range of 1% to 20%, more preferably 1% to 10% and very preferably 1% to 8%;

[0741] and / or

[0742] - compounds of the formula CC-3-V1 and / or CC-4-V1 in a total concentration range of 2 to 20%, more preferably 3 to 15%, particularly preferably 5 to 10%,

[0743] and / or

[0744] - one or more compounds of formula IV-3-1, preferably CC-3-V and / or CC-4-V, preferably in a total concentration range of 20% to 60%, more preferably 25% to 52% and very preferably 28% to 48%;

[0745] and / or

[0746] - one or more compounds of formula IVa, more preferably formula IVa-2, in particular CP-3-O2, in a total concentration ranging from 0.5% to 8%, more preferably from 1% to 6%, very preferably from 2% to 5%;

[0747] and / or

[0748] one or more compounds of formula V, more preferably selected from the compounds of formula V-2-1 and V-2-2, in particular CCP-nm and / or CCP-Vn-m and / or CPP-nm, very particularly selected from CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably in a total concentration ranging from 1% to 20%, more preferably from 2% to 17%, very preferably from 3% to 14%;

[0749] and / or

[0750] one or more compounds selected from the group consisting of compounds of formula V-1-1 and V-1-6, in particular CCC-nm and / or CCC-nV, very particularly CCC-3-V and / or CCC-VV, preferably in a total concentration ranging from 1% to 20%, more preferably from 2% to 17%, very preferably from 3% to 14%;

[0751] and / or

[0752] one or more compounds of formula CL, more preferably formula CL-3, very preferably selected from the compounds CLP-Vm, CLP-V-Om, CLP-nm, and CLP-n-Om, wherein n and m are independently 1, 2, 3, 4 or 5, preferably in a total concentration range of 1% to 12%, more preferably 2% to 10% and very preferably 3% to 7%,

[0753] and / or

[0754] less than 10% in total of one or more compounds of formula V, more preferably less than 5%, very preferably less than 2%, in particular 0%;

[0755] and / or

[0756] One or more compounds of formula COYOIC-nm

[0757] and / or

[0758] One or more compounds of formula COY-n-Om and / or CCOY-n-Om

[0759] and / or

[0760] 0.1% to 3% of the compounds PPGU-3-F and / or PPGU-(c5)-F,

[0761] and / or 0.1 to 3% of 2-(4-methylphenyl)-6-propylnaphthalene:

[0762]

[0763] The medium optionally includes

[0764] - one or more compounds of formula IIB in a total concentration ranging from 1% to 15%, more preferably from 3% to 12% and very preferably from 4% to 10%;

[0765] and / or

[0766] - one or more compounds of formula IIC in a total concentration range of 0.5% to 8%, more preferably 1% to 5% and very preferably 2% to 3%;

[0767] and / or

[0768] - one or more compounds of formula CCU-nF.

[0769] The liquid-crystalline media according to the invention have high voltage holding values ​​in liquid-crystal cells.

[0770] Typically, liquid-crystalline 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.

[0771] As used herein, the term "dielectrically positive compound" refers to compounds with a Δε > 1.5, the term "dielectrically neutral compound" refers to those with a Δε of -1.5 ≤ Δε ≤ 1.5, and the term "dielectrically negative compound" refers to those with a Δε < -1.5. The dielectric anisotropy of the compounds is determined by dissolving 10% of the compound in a liquid crystal host in at least one test cell, each with a layer thickness of 20 μm and homeotropic and planar surface alignment at 1 kHz, and measuring the capacitance of the resulting mixture. The measurement voltage is typically between 0.5 V and 1.0 V, but is always below the capacitance threshold of the respective liquid crystal mixture under investigation.

[0772] All temperature values ​​described in the present invention are expressed in °C.

[0773] The mixtures according to the invention are suitable for all VA-TFT applications, such as, for example, VAN, MVA, (S)-PVA, ASV, PSA (polymer-sustainable VA), and PS-VA (polymer-stabilized VA). They are also suitable for IPS (in-plane switching) and FFS (fringe field switching) applications with negative Δε, in particular UB-FFS.

[0774] It goes without saying for a person skilled in the art that the VA, IPS or FFS mixtures according to the invention may also comprise compounds in which, for example, H, N, O, Cl and F are replaced by corresponding isotopes.

[0775] The compounds according to the present invention can be synthesized by or in analogy to known methods described in the literature (e.g., in standard works, such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart) under reaction conditions known and suitable for the reaction. Variants known per se can also be used herein, but are not mentioned here again. In particular, they can be prepared as described in the following reaction scheme or in analogy to the following reaction scheme. Other methods for preparing the compounds of the present invention can be obtained from the examples.

[0776] Other mesogenic compounds not explicitly mentioned above can also optionally and advantageously be used in the media according to the invention. Such compounds are known to those skilled in the art. DETAILED DESCRIPTION

[0777] For the present invention and in the following examples, the structures of the liquid crystal compounds are indicated by abbreviations, which are converted into chemical formulae 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-1is a straight-chain alkyl group or an alkylene group, each having n, m and 1 C atoms. Preferably, n, m and 1 are independently 1, 2, 3, 4, 5, 6 or 7. Table A shows the codes for the ring elements of the compound core, Table B lists the bridging units, and Table C lists the symbolic meanings of the left-hand and right-hand end groups of the molecule. The abbreviations consist of the code for the ring element with the optional linking group, followed by the first hyphen and the left-hand end group code, and the second hyphen and the right-hand end group code. Table D shows the exemplary structures of the compounds and their respective abbreviations.

[0778] Table A: Ring elements

[0779]

[0780]

[0781]

[0782]

[0783] Table B: Bridge Unit

[0784] Table C: End Groups

[0785]

[0786]

[0787] where n and m are each integers, and the three dots "..." are placeholders for other abbreviations from the table.

[0788] The medium according to the invention preferably comprises one or more compounds mentioned in Table D below.

[0789] The following abbreviations are used:

[0790] (n, m, k and l are each independently an integer, preferably 1 to 9, preferably 1 to 7, k and l may also be 0 and preferably 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").

[0791] Table D

[0792]

[0793]

[0794]

[0795]

[0796]

[0797]

[0798]

[0799]

[0800]

[0801]

[0802]

[0803]

[0804]

[0805]

[0806]

[0807]

[0808]

[0809]

[0810]

[0811]

[0812] Table E

[0813] Table E shows illustrative reactive mesogenic compounds that can be used in the LC media according to the invention.

[0814]

[0815]

[0816]

[0817]

[0818]

[0819]

[0820]

[0821]

[0822]

[0823]

[0824]

[0825]

[0826]

[0827]

[0828]

[0829]

[0830]

[0831]

[0832]

[0833] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the group consisting of formulae RM-1 to RM-182. Among these, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-58, RM-64, RM-74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-145, RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-183 are particularly preferred.

[0834] Example

[0835] The present invention is illustrated in detail by the following non-limiting working examples.

[0836] The following abbreviations and symbols are used:

[0837] V0 represents the threshold voltage at 20°C, capacitive [V],

[0838] n e represents the extraordinary refractive index at 20°C and 589nm,

[0839] n o represents the ordinary refractive index at 20°C and 589nm,

[0840] △n represents the optical anisotropy at 20℃ and 589nm,

[0841] ε ⊥ represents the dielectric constant perpendicular to the director at 20°C and 1kHz,

[0842] ε|| represents the dielectric constant parallel to the director at 20°C and 1kHz,

[0843] △ε represents the dielectric anisotropy at 20℃ and 1kHz,

[0844] cl.p., T(N,I) represents the clearing point [℃],

[0845] γ1 represents the rotational viscosity at 20°C [mPa·s],

[0846] K1 represents the elastic constant, the "bending" deformation at 20°C [pN],

[0847] K2 represents the elastic constant, the "twist" deformation at 20°C [pN],

[0848] K3 represents the elastic constant, the "bending" deformation at 20°C [pN],

[0849] Unless expressly stated otherwise, all concentrations in the present application are expressed as percentages by weight and relate to the respective mixture as a whole, including all solid or liquid-crystalline components, without solvent.

[0850] Unless otherwise expressly stated, all temperature values ​​stated in this application, such as 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), are quoted in degrees Celsius (°C). Mp = melting point, cl.p. = clearing point. Furthermore, C = crystalline phase, N = nematic phase, S = smectic phase, and I = isotropic phase. The data between these symbols represent transition temperatures.

[0851] Unless expressly stated otherwise, all physical properties are and have been determined in each case in accordance with “Merck Liquid Crystals, Physical Properties of Liquid Crystals”, Status Nov. 1997, Merck KGaA, Germany, and apply to a temperature of 20° C., with Δn at 589 nm and Δε at 1 kHz.

[0852] The term "threshold voltage" as used in the present invention relates to the capacitive threshold (V0), which is also called the Freedericks threshold, unless explicitly stated otherwise. In embodiments, as is common, the optical threshold may also be the relative contrast (V 10 ) cited.

[0853] Unless otherwise stated, the processes for polymerising the polymerisable compounds in PSA displays as described above and below are carried out at a temperature at which the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably at room temperature.

[0854] Unless otherwise stated, the methods for preparing the test cells and measuring their electro-optical and other properties shall be those described below or similar thereto.

[0855] The display used to measure the capacitive threshold voltage consisted of two plane-parallel glass outer plates 25 μm apart, each with an electrode layer on the inside and an unrubbed polyimide alignment layer on top, which resulted in homeotropic alignment of the liquid crystal molecules.

[0856] The display or test cell used to measure the tilt angle consists of two plane-parallel glass outer plates separated by 4 μm, each of which has an electrode layer on the inside and a polyimide alignment layer on top, where the two polyimide layers are rubbed antiparallel to each other and induce vertical edge alignment of the liquid crystal molecules.

[0857] The polymerizable compound is polymerized in the display or test box by irradiating with UV light of defined intensity for a predetermined time while applying a voltage to the display (typically 10V-30V AC, 1kHz). In the examples, unless otherwise stated, fluorescent lamps and 0 to 20 mW / cm 2 The intensity was measured using a standard instrument (Ushio Accumulate UV meter with a central wavelength of 313 nm).

[0858] Transmission measurements were performed in a test cell with a fishbone electrode layout (from Merck Ltd., Japan; 1 pixel fishbone electrode (ITO, 10x10 mm, fishbone angle 47.7°, 3 μm line / 3 μm space), 3.2 μm cell gap, AF-glass, tilt angle 1°).

[0859] At a given temperature T, the storage stability (LTS) in the bulk of the medium according to the invention is 本体 ) is determined by visual inspection. 2 g of the medium of interest is filled into a closed glass container (bottle) of appropriate size and placed in a refrigerator at a predetermined temperature. The bottles are inspected at defined time intervals for the development of a smectic phase or crystallization. Two bottles are stored for each material and temperature. If the development of crystallization or a smectic phase is observed in at least one of the two corresponding bottles, the test is terminated, and the time of the last inspection before the development of a higher-order phase is observed is recorded as the corresponding storage stability.

[0860] Mixture Examples

[0861] The following stabilizers were used:

[0862]

[0863]

[0864] Nematic LC host mixtures H1 to H16 and mixture examples N1 to N18 have the compositions and properties given in the table below.

[0865] Main mixture H1

[0866]

[0867]

[0868] Main mixture H2

[0869]

[0870] Host mixture H3

[0871]

[0872]

[0873] Main mixture H4

[0874]

[0875] Main mixture H5

[0876]

[0877] Main mixture H6

[0878]

[0879]

[0880] Main mixture H7

[0881]

[0882] Main mixture H8

[0883]

[0884]

[0885] Main mixture H9

[0886]

[0887] Main mixture H10

[0888]

[0889]

[0890] Main mixture H11

[0891]

[0892] Main mixture H12

[0893]

[0894]

[0895] Main mixture H13

[0896]

[0897] Main mixture H14

[0898]

[0899]

[0900] Main mixture H15

[0901]

[0902] Main mixture H16

[0903]

[0904] Comparative Example C1

[0905]

[0906] Comparative Example C2

[0907]

[0908] Comparative Example C3

[0909]

[0910] Comparative Example C4

[0911]

[0912] Mixture Example N1

[0913]

[0914] Mixture Example N2

[0915]

[0916] Mixture Example N3

[0917]

[0918]

[0919] Comparative Example C5

[0920]

[0921] Comparative Example C6

[0922]

[0923] Comparative Example C7

[0924]

[0925] Comparative Example C8

[0926]

[0927] Mixture Example N4

[0928]

[0929] Mixture Example N5

[0930]

[0931] Mixture Example N6

[0932]

[0933] Mixture Example N7

[0934]

[0935] Mixture Example N8

[0936]

[0937] Mixture Example N9

[0938]

[0939] Mixture Example N10

[0940]

[0941] Mixture Example N11

[0942]

[0943] Mixture Example N12

[0944]

[0945]

[0946] Mixture Example N13

[0947]

[0948] Mixture Example N14

[0949]

[0950] Mixture Example N15

[0951]

[0952] Mixture Example N16

[0953]

[0954]

[0955] Mixture Example N17

[0956]

[0957] Mixture Example N18

[0958]

[0959] Stress testing

[0960] The above mixtures were subjected to backlight and thermal stress tests as shown below. A test box (AF glass, 1 cm x 11 cm ITO electrode, box gap 3.5 μm) with a polyimide alignment layer (JSR3225, Japan Synthetic Rubber (JSR), Japan, layer thickness 65 nm, rubbed) was filled with the corresponding mixture and their voltage retention was measured using a 6254 type measurement system from Toyo Corporation of Japan before and after irradiation. The test box was irradiated by exposure to a commercial LCD TV white backlight (CCFL) (without filter). Due to the heat release of the backlight, the temperature of the test box during irradiation was approximately 50°C. The VHR was measured after storage at 60°C for 30 minutes. The voltage was 1 V at a frequency of 60 Hz and 3 Hz, respectively. The results are summarized in Tables 1 and 2 below.

[0961] Table 1: VHR values ​​after backlight load [1]

[0962]

[0963]

[0964] [1] Measured at 60Hz, 60℃

[0965] Table 2: VHR values ​​after backlight load [2]

[0966]

[0967] [2] Measured at 3Hz, 60℃

[0968] By adding a stabilizer of formula ST and a second stabilizer of formula Ia or Ib (mixtures C1 to C4), the VHR after backlight loading of the stabilizer-free host mixture H1 can be improved.

[0969] Surprisingly, the VHR can be further significantly improved by using a combination of three stabilizers of formula ST and Ia and Ib (mixtures N1, N2 and N3).

Claims

1. A liquid crystal medium comprising: a) one or more compounds of formula ST in R S1 represents a straight-chain alkyl radical having 1 to 12 C atoms or a branched-chain alkyl radical having 3 to 12 C atoms, wherein one or more CH2 groups in these radicals may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- is replaced in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen, R S2 represents H, alkyl or alkoxy radicals having 1 to 7 C atoms, or alkenyl radicals having 2 to 7 C atoms, where one or more H atoms in these radicals may be replaced by halogen, W 1 , W 2 , W 3 , W 4 Identically or differently, represents O or CH2, and r1 and r2 are independently 0 or 1; b) one or more compounds of formula Ia in W stands for CH 4-s or an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms; A, on each occurrence, identically or differently, represents a single bond or a straight-chain alkylene radical having 1 to 20 carbon atoms or a straight-chain alkenylene radical having 2 to 20 carbon atoms or a branched alkylene radical or alkenylene radical each having 3 to 12 carbon atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CH=CH-, -C(O)-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen and one or two H atoms may be replaced by a radical -Z S -HA a Replacement; R S represents H, an alkyl group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms; Z S Indicates -O-, -C(O)O-, -(CH2) z -or-(CH2) z O-, or single bond; HA a express R S1 , R S2 , R S3 and R S4 , identically or differently, represent an alkyl group having 1 to 6 C atoms; G means H or R S or group Z S -HA a ; z is an integer from 1 to 6, and s is 2, 3 or 4; c) one or more compounds of formula Ib W stands for CH 4-s or an aromatic hydrocarbon group having 6 to 40 C atoms or a heteroaromatic hydrocarbon group having 4 to 40 C atoms; A, on each occurrence, identically or differently, represents a single bond or a straight-chain alkylene radical having 1 to 20 carbon atoms or a straight-chain alkenylene radical having 2 to 20 carbon atoms or a branched alkylene radical or alkenylene radical each having 3 to 12 carbon atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -C≡C-, -CH=CH-, -C(O)-, -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen and one or two H atoms may be replaced by a radical -Z S -HA b Replacement; R S represents H, an alkyl group having 1 to 12 C atoms or an alkenyl group having 2 to 12 C atoms; Z S Indicates -O-, -C(O)O-, -(CH2) z -or-(CH2) z O-, or single bond; HA b express R S1 , R S2 , R S3 and R S4 , identically or differently, represent an alkyl group having 1 to 6 C atoms; G means H or R S or group Z S -HA b ; z is an integer from 1 to 6, and s is 2, 3 or 4; and d) one or more compounds selected from the group consisting of compounds of formula IIA, IIB, IIC and IID in R 2A , R 2B , R 2C and R 2D Identically or differently, represents H, a straight-chain alkyl or alkoxy radical having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy radical having 2 to 15 C atoms or a branched alkyl, alkoxy, alkenyl, alkenyloxy radical each having 3 to 15 C atoms, wherein one or more CH2 radicals in these radicals may each independently of one another be replaced by -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO- is replaced in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen, L 1 and L 2 , 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-, (O) represents O or a single bond, p represents 0, 1 or 2, q represents 0 or 1, and v represents an integer from 1 to 6.

2. The liquid-crystalline medium according to claim 1 , wherein the compound of formula ST is selected from the compounds of formulae ST-1 and ST-2: in R S1 has the meaning given in claim 1 and r is 0 or 1.

3. The liquid-crystalline medium according to claim 1 , wherein the medium comprises one or more compounds of the formula Ia selected from compounds of the formula Ia-1: in R S3 represents H or an alkyl group having 1 to 6 C atoms, t is 0 or 1, and q is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9.

4. Liquid-crystalline medium according to one or more of claims 1 to 3, wherein the compound of formula Ib is selected from the group consisting of compounds of formulae Ib-1, Ib-2, Ib-3 and Ib-4: in R S3 represents H or an alkyl group having 1 to 6 C atoms, t is 0 or 1, q is 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9, A and R S has the meaning defined in claim 1, and W 1 represents a straight-chain or branched, optionally unsaturated alkylene radical having 1 to 12 C atoms, in which one or more non-adjacent -CH2- groups may be replaced by -O-.

5. Liquid-crystalline medium according to one or more of claims 1 to 4, wherein the medium comprises one or more compounds of the formula IID according to claim 1.

6. The liquid crystal medium according to claim 5, wherein the compound of formula IID is selected from the group consisting of compounds of formulae IID-4 and IID-10 in Alkyl and alkyl* each independently represent a straight-chain alkyl radical having 1 to 6 C atoms, and (O) represents an oxygen atom or a single bond.

7. Liquid-crystalline medium according to one or more of claims 1 to 6, wherein the medium comprises one or more compounds of the formula III in R 31 and R 32 each independently of one another represents H, alkyl or alkoxy having 1 to 15 C atoms, wherein one or more CH2 groups in these radicals may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, are replaced by -O-, -CO-O- or -O-CO- in such a way that the O atoms are not directly connected to each other, and wherein one or more H atoms may be replaced by halogen, A 31 Each occurrence represents independently of each other a) 1,4-cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-, b) 1,4-phenylene, in which one or both CH groups may be replaced by N, or c) a radical selected from the group consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, wherein the groups a), b) and c) may be mono- or polysubstituted by halogen atoms, Z 31 Each occurrence independently 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, n represents 0, 1 or 2, L 31 and L 32 each independently represents F, Cl, CF3 or CHF2, and W represents O or S.

8. Liquid-crystalline medium according to one or more of claims 1 to 7, wherein the medium comprises one or more compounds of the formula IIA-Y in R 11 and R 12 With respect to R in the formula IIA in claim 1 2A The meaning given, and L 1 and L 2 , identically or differently, represent F or Cl.

9. The medium according to one or more of claims 1 to 8, wherein the medium comprises one or more compounds selected from the group consisting of compounds of formulae BC, CR, PH-1 and PH-2: in R B1 , R B2 , R CR1 , R CR2 , R P1 , R P2 each independently of one another represents H, an alkyl or alkoxy group having 1 to 15 C atoms, wherein one or more CH2 groups in these groups may each independently of one another be -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO- are replaced in such a way that the O atoms are not directly bonded to one another, and wherein one or more H atoms may be replaced by halogen, and c is 0, 1 or 2.

10. Liquid-crystalline medium according to one or more of claims 1 to 9, wherein the medium comprises one or more compounds of the formula IV in R 41 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, and R 42 represents an unsubstituted alkyl group having 1 to 7 C atoms, an unsubstituted alkoxy group having 1 to 6 C atoms, or an unsubstituted alkenyl group having 2 to 7 carbon atoms.

11. Liquid-crystalline medium according to one or more of claims 1 to 10, wherein the medium comprises one or more additives selected from the group consisting of dichroic dyes, chiral dopants and polymerizable compounds.

12. A liquid crystal display comprising a liquid crystal medium as defined in any one of claims 1 to 11.

13. The liquid crystal display according to claim 12, wherein the display is a VA, IPS or FFS type display.

14. Use of the liquid-crystalline medium according to one or more of claims 1 to 11 in VA, IPS, FFS, PS-VA, PS-IPS or PS-FFS displays.

15. A method for producing a liquid crystal medium according to any one of claims 1 to 11, comprising the following steps: One or more compounds of formula ST as defined in claim 1 are mixed with one or more compounds of formula Ia and with one or more compounds of formula Ib and with one or more compounds selected from the group consisting of compounds of formulae IIA, IIB, IIC and IID, and optionally with other liquid crystal compounds or additives.

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