Liquid crystal media

Abstract

A liquid crystal medium is provided. [Solution] The present invention relates to a liquid crystal medium as defined in claim 1 which comprises a) one or more compounds of formula I, b) one or more compounds selected from the group of formulae IIA, IIB, IIC and IID and c) one or more compounds of formula III and has negative dielectric anisotropy, and to the use of this LC medium which is beneficial for optical, electro-optical and electronic purposes, in particular for enabling energy-saving LC displays of the VA, IPS or FFS type. TIFF2024541860000241.tif178166

Description

[Technical field]

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

[0002] One of the liquid-crystal display (LCD) modes currently in use is the TN ("twisted nematic") mode. However, TN LCDs have the disadvantage that their contrast is highly dependent on the viewing angle.

[0003] In addition, so-called VA ("vertically aligned") displays are known which have wider viewing angles. The LC cell of a VA display comprises a layer of an LC medium between two transparent electrodes, where the LC medium usually has a negative dielectric anisotropy. In the switched-off state the molecules of the LC layer are aligned perpendicular to the electrode surfaces (homeotropic) or have a tilted homeotropic alignment. Upon application of a voltage to the two electrodes a reorientation of the LC molecules occurs parallel to the electrode surfaces.

[0004] Also known are so-called IPS ("in-plane switching") displays which have an LC layer between two substrates, in which two electrodes are arranged on only one of the two substrates, preferably with an interdigitated comb-like structure. When a voltage is applied to the electrodes, this creates an electric field between the electrodes which has a significant component parallel to the LC layer. This leads to a reorientation of the LC molecules in the layer plane.

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

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

[0007] Further disclosed are FFS displays with electrode designs and layer thicknesses similar to those of FFS displays, but with LC medium layers with negative dielectric anisotropy instead of LC medium layers with positive dielectric anisotropy (see, for example, S.H. Lee et al., Appl. Phys. Lett. vol. 73 (no. 20), 1998, pp. 2882-2883 (Non-Patent Document 2) and S.H. Lee et al., Liquid Crystals vol. 39 (no. 9), 2012, pp. 1141-1148 (Non-Patent Document 3)). LC media with negative dielectric anisotropy exhibit a more favorable director alignment with less tilt and a higher twist alignment than LC media with positive dielectric anisotropy, and as a result these displays have higher transparency. The displays further comprise an alignment layer, preferably a polyimide alignment layer provided on at least one of the substrates, which is in contact with the LC medium and induces a planar alignment of the LC molecules of the LC medium. These displays are also known as "Ultra Brightness FFS" mode displays. These displays require a highly reliable LC medium.

[0008] In more recent types of VA displays, the uniform alignment of the LC molecules is restricted to relatively small domains within the LC cell. Disclinations may exist between these domains, also known as tilt domains. VA displays with tilt domains have larger contrast-independent viewing angles and grey levels compared to conventional VA displays. In addition, this type of display is easier to manufacture, and further treatment of the electrode surface, for example by rubbing, to achieve a uniform alignment of the molecules in the switched-on state is no longer necessary. Instead, the preferred direction of the tilt or pretilt angle is controlled by a special design of the electrodes.

[0009] In so-called MVA ("multidomain vertical alignment") displays, this is usually achieved by electrodes with protrusions, which cause a local pretilt. As a result, the LC molecules are aligned parallel to the electrode surface in different directions and in different defined areas of the cell when a voltage is applied. This achieves a "controlled" switch and prevents the formation of interfering disclination lines. This arrangement improves the viewing angle of the display, but results in a lower transparency to light. A further development of MVA uses protrusions only on one electrode side, while the opposite electrode has slits, which improves the transparency to light. The slit electrodes generate a non-uniform electric field in the LC cell when a voltage is applied, which means that controlled switching is still achieved. To further improve the transparency to light, the distance between the slits and the protrusions can be increased, but this in turn results in a longer response time. In so-called PVA ("patterned VA") displays, the protrusions are fully redundant in that both electrodes are structured with slits on the opposite side, which results in increased contrast and improved transmission to light, but is technically difficult and makes the display more sensitive to mechanical influences (such as "tapping"). However, for many applications, such as monitors and especially television screens, shorter response times and improvements in the contrast and brightness (transmission) of the displays are required.

[0010] Further developments are the so-called PS ("polymer sustained") or PSA ("polymer sustained alignment") type displays, for which the term "polymer stabilised" is sometimes also used. In these displays, small amounts (e.g. 0.3% by weight, typically less than 1% by mass) of one or more polymerisable compound(s), preferably polymerisable monomeric compound(s), are added to the LC medium and polymerised or crosslinked in situ after filling the LC medium into the display, usually by UV photopolymerisation, optionally with the application of a voltage to the electrodes of the display. The polymerisation is carried out at a temperature at which the LC medium exhibits a liquid crystal phase, usually at room temperature. The addition of polymerisable mesogens or liquid crystal compounds, also known as reactive mesogens or "RMs", to the LC mixture has proven to be particularly suitable.

[0011] On the other hand, the PS(A) principle is 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. Polymerization of the RM is preferably carried out with applied voltage in the case of PS-VA and PS-OCB displays, and with or without applied voltage, preferably without applied charge, in the case of PS-IPS displays. As can be demonstrated in test cells, the PS(A) method results in a pretilt in the cell. In the case of PS-VA displays, the pretilt has a positive effect on the response time. For PS-VA displays, standard MVA or PVA pixel and electrode layouts can be used. In addition, however, it is also possible to make do without protrusions, for example with only one structured electrode side, which significantly simplifies the production and at the same time results in a very good contrast and at the same time a very good transparency for light.

[0012] PS-VA displays are described, for example, in EP 1170626 (Patent Document 1), U.S. Patent No. 6,861,107 (Patent Document 2), U.S. Patent No. 7,169,449 (Patent Document 3), U.S. Patent Application Publication No. 2004 / 0191428 (Patent Document 4), U.S. Patent Application Publication No. 2006 / 0066793 (Patent Document 5) and U.S. Patent Application Publication No. 2006 / 0103804 (Patent Document 6). PS-OCB displays are described, for example, in T.-J-Chen et al., Jpn.J.Appl.Phys., Vol. 45, 2006, pp. 2702-2704 (Non-Patent Document 4) and SH Kim, L.-C-Chien, Jpn.J.Appl.Phys., Vol. 43, 2004, pp. 7643-7647 (Non-Patent Document 5). PS-IPS displays are described, for example, in U.S. Patent No. 6,177,972 (Patent Document 7) and Appl. Phys. Lett. 1999, Vol. 75 (No. 21), p. 3264 (Non-Patent Document 6). PS-TN displays are described, for example, in Optics Express 2004, Vol. 12 (No. 7), p. 1221 (Non-Patent Document 7).

[0013] PSA displays typically have an alignment layer on one or both of the substrates forming the display cell below the layer formed by the phase separated and polymerized RM inducing the pretilt angle mentioned above, which provides an initial alignment of the LC molecules before the polymer stabilization step. The alignment layer is usually applied on top of an electrode (if such an electrode is present) so as to be in contact with the LC medium and induce an initial alignment of the LC molecules. The alignment layer may for example comprise or consist of polyimide and may be rubbed or prepared by photoalignment methods.

[0014] Like the conventional LC displays described above, PSA displays can be operated as active matrix displays or passive matrix displays. In the case of active matrix displays, the individual pixels are typically addressed by integrated nonlinear active elements, such as transistors (e.g. thin film transistors ("TFTs")), whereas in the case of passive matrix displays, the individual pixels are typically addressed by multiplexing methods as known from the prior art.

[0015] Especially for monitor and especially television applications, there is a continuing demand for optimization of the response time but also the contrast and brightness (and therefore also the transmission) of LC displays. Here, the PSA method can offer significant advantages: especially for PS-VA, PS-IPS and PS-FFS displays, a reduction in the response time, which correlates with the pretilt measurable in test cells, can be achieved without significant adverse effects on other parameters.

[0016] 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 results in mura in the display, especially when the LC media is filled into display cells manufactured using the one drop filling (ODF) method. This phenomenon is also known as "ODF mura". It is therefore desirable to provide an LC medium that leads to reduced ODF mura.

[0017] Another problem observed in the prior art is that LC media for use in displays, including but not limited to PSA type displays, often exhibit high viscosity and, as a result, high switching times. To reduce the viscosity and switching time of the LC medium, it has been suggested in the prior art to add LC compounds with alkenyl groups. However, it has been observed that LC media containing alkenyl compounds often exhibit reduced reliability and stability as well as reduced VHR, especially after exposure to UV radiation. In particular, since the photopolymerization of RM in PSA displays is usually carried out by exposure to UV radiation, this can cause a reduction in the VHR in the LC medium, which is quite disadvantageous for use in PSA displays.

[0018] Especially from the perspective of mobile devices, there is a great demand for displays with high transmittance, which will require less backlighting and therefore longer battery life, but in return can of course enable brighter displays with improved contrast, especially under ambient light.

[0019] In addition, there is a great demand for displays, and LC media for use in such displays, which enable a large operating temperature range as well as high resistivity, short response times even at low temperatures, and low threshold voltages, low pretilt angles, a large number of grey levels, high contrast and wide viewing angles, high reliability and high values ​​for VHR after UV exposure, and, in the case of polymerizable compounds, low melting points and high solubility in LC host mixtures. For PSA displays for mobile applications, it is particularly desirable to have available LC media exhibiting low threshold voltages and high birefringence. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] European Patent Application Publication No. 1170626 [Patent Document 2] U.S. Patent No. 6,861,107 Specification [Patent Document 3] U.S. Patent No. 7,169,449 Specification [Patent Document 4] U.S. Patent Application Publication No. 2004 / 0191428 Specification [Patent Document 5] U.S. Patent Application Publication No. 2006 / 0066793 Specification [Patent Document 6] U.S. Patent Application Publication No. 2006 / 0103804 Specification [Patent Document 7] U.S. Patent No. 6,177,972 Specification [Non-Patent Document]

[0021] [Non-Patent Document 1] By S.H. Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, p. 1028 [Non-Patent Document 2] By S.H. Lee et al., Appl. Phys. Lett. Vol. 73 (No. 20), 1998, pp. 2882 - 2883 [Non-Patent Document 3] By S.H. Lee et al., Liquid Crystals Vol. 39 (No. 9), 2012, pp. 1141 - 1148 [Non-Patent Document 4] By T.-J-Chen et al., Jpn. J. Appl. Phys. Vol. 45, 2006, pp. 2702 - 2704 [Non-Patent Document 5] By S.H. Kim, L.-C-Chien, Jpn. J. Appl. Phys. Vol. 43, 2004, pp. 7643 - 7647 [Non-Patent Document 6] Appl. Phys. Lett. 1999, Vol. 75 (No. 21), p. 3264 [Non-Patent Document 7] Optics Express 2004, Vol. 12 (No. 7), p. 1221 [Summary of the Invention] [Problem to be solved by the invention]

[0022] The present invention is based on the object of providing new suitable LC media for use in displays, which may comprise reactive mesogens (RM) and which do not have the disadvantages indicated above, or have them to a reduced extent.

[0023] In particular, the present invention is based on the object of an LC medium which allows displays having high transmittance and at the same time very high resistivity values, high VHR values, high reliability, low threshold voltages, short response times, high birefringence, reducing or preventing the occurrence of "image sticking" and "ODF mura" in the displays, and in the case of media containing RMs, allows a fast polymerization which is as rapid and complete as possible and shows high solubility of the RM in the LC medium used as host mixture in PSA displays. [Means for solving the problem]

[0024] These objects have been achieved according to the present invention by the materials and methods as described in this application. It has been particularly surprising to find that the above mentioned advantageous effects can be achieved by using a liquid crystal host as described hereinafter.

[0025] The present invention relates to a liquid-crystalline medium comprising a) one or more compounds of formula I, b) one or more compounds selected from the group of formulae IIA, IIB, IIC and IID, c) one or more compounds of formula III and d) optionally a reactive mesogen.

[0026] [ka]

[0027] During the ceremony, R 1 represents n-butyl or n-pentyl.

[0028] [ka]

[0029] During the ceremony, R 2A , R 2B , R 2C and R 2D each independently represents H, an alkyl group having 1 to 7 C atoms, or an alkenyl group having 2 to 7 C atoms, each of which is unsubstituted or at least monosubstituted with a halogen, provided that one or more CH2 groups in these groups are -O-, -S-, ... [ka] may be replaced by -C≡C-, -CF2O-, -OCF2-, -OC-O- or -O-CO-; 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 represent, independently of one another, a single bond, -CHCH-, -CH=CH-, -CF-CF-, -CF=CF-, -CFO-, -OCF-, -CHO-, -OCH-, -COO-, or -OCO-; p represents 0, 1 or 2; q represents 0 or 1, and v represents 1, 2, 3, 4, 5 or 6.

[0030] [ka]

[0031] During the ceremony, R 31 and R 32each independently represent H, an alkyl or alkoxy group having 1 to 7 C atoms, with the proviso that one or more CH2 groups in these groups are not directly linked to O atoms, [ka] each independently being replaced by -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO-, in which one or more H atoms may be replaced by halogen; A 3 represent, independently at each occurrence, a 1,4-phenylene radical in which one or two CH groups may be replaced by N, or a 1,4-cyclohexenylene or 1,4-cyclohexylene radical in which one or two non-adjacent CH groups may be replaced by -O- or -S-, with the proviso that the radicals may be mono- or polysubstituted by halogen atoms, n represents 0, 1 or 2; Z 3 represent, independently in each occurrence, -CF2O-, -OCF2-, -CHO-, -OCH2-, -CH2-, -CH2CH2-, -CH=CH-, -C≡C- or a single bond, L 31 and L 32 each independently represents F, Cl, CF3 or CHF2, and W represents O or S.

[0032] The invention further relates to an LC display comprising an LC medium as described above and below.

[0033] The present invention further relates to a method for preparing an LC medium as described above and below, comprising the step of mixing one or more compounds of formulae I and III and one or more compounds selected from formulae IIA, IIB, IIC and IID, optionally with reactive mesogens and further LC compounds and / or additives.

[0034] The present invention further relates to the use of the LC medium according to the invention in PSA displays, preferably in particular in PSA displays comprising an LC medium for the generation of a tilt angle in the LC medium by in situ polymerization of a polymerizable compound in the PSA display in an electric or magnetic field. Preferred polymerizable compounds, also called reactive mesogens (RM), are described for example in EP 3 839 008 A1, paragraphs 0094 and 0155 and pages 111 to 129, which are hereby incorporated by reference.

[0035] The invention further relates to an LC display of the IPS, FFS, UB-FFS, UBplus, VA or PS-VA type which contains an LC medium according to the invention.

[0036] The invention further relates to the use of an LC medium according to the invention in a polymer stabilized SA-VA display and to a polymer stabilized SA-VA display comprising an LC medium according to the invention.

[0037] The invention further relates to an LC display of the VA or PSA type comprising two substrates, at least one of which is transparent to light, an electrode provided on each substrate or two electrodes provided on only one of the substrates, and a layer of an LC medium as described above and below, comprising one or more polymerizable compounds and an LC component, located between the substrates, with the proviso that the polymerizable compound is polymerized between the substrates of the display.

[0038] The invention further 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 as described above and below between the substrates of the display, which may comprise one or more polymerisable compounds, and optionally polymerising the polymerisable compounds.

[0039] Preferred embodiments are the subject matter of the dependent claims and can also be taken from this specification.

[0040] PSA displays according to the invention have two electrodes, preferably in the form of transparent layers, coated on one or both of the substrates. In some displays, for example PS-VA displays, one electrode is coated on each of the two substrates.

[0041] In a preferred embodiment the polymerisable component is polymerised in an LC display whilst a voltage is applied to the electrodes of the display.

[0042] The polymerizable compounds of the polymerizable component are preferably polymerized by photopolymerization, very preferably by UV photopolymerization.

[0043] Surprisingly, it has been found that the use of the liquid crystal media according to the invention allows displays with improved transmission and high reliability, with fast response times, generally fast response times, low threshold voltages, high birefringence as well as improved transmittance when exposed to outdoor environments, while maintaining excellent performance with regard to process-relevant parameters, i.e. in the case of PSA displays, without the addition of photoinitiators, in particular at long UV wavelengths in the range of 300-380 nm, in particular above 320 nm, resulting in rapid generation of large and stable pretilt angles, reduced image sticking and ODF mura in the displays.

[0044] In particular, the media according to the invention are distinguished by excellent low-temperature stability (LTS).

[0045] The LC media according to the invention, when used in VA or FFS displays, exhibit the following advantageous properties: Improved transparency of the display, High clearing temperature, -High voltage holding ratio, -Fast switch, - sufficient stability against heat and / or UV, especially when used outdoors, -Great LTS.

[0046] The LC media according to the invention, when used in PSA displays, exhibit the following advantageous properties: Improved transparency of the display, High clearing temperature, Proper tilt generation within a specific process window, Fast polymerization with minimal RM residue after UV processing, High voltage retention after UV processing, Good tilt stability, - sufficient stability against heat and / or UV, especially when used outdoors, -Fast switch.

[0047] In particular, the liquid-crystalline media according to the invention exhibit a favourably low ratio of the rotational viscosity to the splay elastic constant γ1 / K1, which contributes to improved switching behaviour especially at low driving voltages and is useful for the realisation of energy-saving displays. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Preferred compounds of formula IIA, IIB, IIC and IID are shown below.

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] In the formula, the parameter a represents 1 or 2, and alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 C atoms, alkenyl represents a linear alkenyl group having 2 to 6 C atoms, (O) represents an oxygen atom or a single bond, preferably an oxygen atom. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0062] Highly preferred compounds of formula IID are selected from the following subformulae:

[0063] [ka]

[0064] [ka]

[0065] [ka]

[0066] [ka]

[0067] [ka]

[0068] In the formula, v represents 1, 2, 3, 4, 5 or 6.

[0069] In a preferred embodiment, the medium comprises one or more compounds of formula IID-10a.

[0070] [ka]

[0071] in which the occurring groups and parameters have the meanings given above under formula IID, and R 2 teeth, [ka] wherein r is 0, 1, 2, 3, 4, 5 or 6; and s is 1, 2 or 3.

[0072] Preferred compounds of formula IID-10a are compounds IID-10a-1 to IID-10a-14.

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] More preferred media according to the invention comprise 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.

[0077] Highly preferred media according to the invention comprise one or more compounds of formula IIB-2.

[0078] [ka]

[0079] In the formula, alkyl and alkyl * each independently of one another represents a linear alkyl group having 1 to 6 C atoms and (O) represents an oxygen atom or a single bond, in particular the compounds of the formulae IIB-2-1 and IIB-2-2.

[0080] [ka]

[0081] A preferred medium according to the invention comprises at least one compound of formula IIC-1, preferably in an amount of 0.5% to 5% by weight, in particular 1% to 3% by weight.

[0082] [ka]

[0083] In the formula, alkyl and alkyl * has the meaning given above.

[0084] In particular, the medium comprises one or more compounds of formula IIA-2 selected from the following subformulae:

[0085] [ka]

[0086] Alternatively and preferably, in addition to the compounds of formulae IIA-2-1 to IIA-2-5, the medium comprises one or more compounds of formulae IIA-2a-1 to IIA-2a-5.

[0087] [ka]

[0088] In particular, the medium comprises one or more compounds of formula IIA-10 or IIA-52 selected from the following subformulae:

[0089] [ka]

[0090] Alternatively and preferably, in addition to the compounds of formulae IIA-10-1 to IIA-10-5, the medium comprises one or more compounds of formulae IIA-10a-1 to IIA-10a-5.

[0091] [ka]

[0092] In particular, the medium comprises one or more compounds of formula IIB-10 selected from the following subformulas:

[0093] [ka]

[0094] Alternatively and preferably, in addition to the compounds of formulae IIB-10-1 to IIB-10-5, the medium comprises one or more compounds of formulae IIB-10a-1 to IIB-10a-5.

[0095] [ka]

[0096] The compound of formula III is preferably selected from the compounds of formulae III-1, III-2 and / or III-4.

[0097] [ka]

[0098] in which the occurring radicals have the same meaning as given above in formula III, preferably R 31 and R 32 are each independently an alkyl or alkoxy group having 1 to 15 C atoms or an alkenyl group having 2 to 15 C atoms, more preferably one or both of them are an alkoxy group having 1 to 7 C atoms, L 11 and L 12 preferably represents F.

[0099] The liquid-crystalline medium according to the invention preferably comprises one or more compounds of the formula III-2. In a preferred embodiment, the liquid-crystalline medium comprises at least one compound of the formula III-1 and at least one compound of the formula III-2. In a further preferred embodiment, the liquid-crystalline medium comprises at least one compound of the formula III-2 and at least one compound of the formula III-3.

[0100] Preferably, the compound of formula III-1 is selected from the group of the compounds of formulae III-1-1 to III-1-10, preferably of formula III-1-6.

[0101] [ka]

[0102] [ka]

[0103] During the ceremony, Alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms, and alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 carbon atoms, alkoxy and alkoxy * each independently represents a linear alkoxy group having 1 to 6 C atoms; L 31 and L 32 each independently represents F or Cl, preferably both represent F.

[0104] Preferably, the compound of formula III-2 is selected from the group of the compounds of formulae III-2-1 to III-2-10, preferably of formula III-2-6.

[0105] [ka]

[0106] [ka]

[0107] During the ceremony, Alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms, and alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 carbon atoms, alkoxy and alkoxy * each independently represents a linear alkoxy group having 1 to 6 C atoms; L 31 and L 32 each independently represents F or Cl, preferably both represent F.

[0108] The medium may contain one or more compounds of formula IIIA-1 and / or IIIA-2.

[0109] [ka]

[0110] In the formula, L 31 and L 32 has the same meaning as given above in formula III, (O) represents O or a single bond, R IIIA is an alkyl or alkenyl group having up to 7 C atoms or a group Cy-C m H 2m+1 - represents m and n are the same or different and are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy represents alkyl or alkenyl, each having up to 3 C atoms, or an alicyclic group having 3, 4 or 5 ring atoms, which may be substituted by halogen or CN, and preferably represents cyclopropyl, cyclobutyl, cyclopentyl or cyclopentenyl.

[0111] The compounds of formula IIIA-1 and / or IIIA-2 are included in the medium either alternatively or additionally, preferably additionally, to the compound of formula III.

[0112] Highly preferred compounds of formula IIIA-1 and IIIA-2 are:

[0113] [ka]

[0114] In the formula, alkoxy is a linear alkoxy group having 1 to 6 C atoms, or alternatively -(CH2) n F (wherein n is 2, 3, 4 or 5), preferably C2H4F.

[0115] In a preferred embodiment of the invention, the medium comprises one or more compounds of formula III-3.

[0116] [ka]

[0117] During the ceremony R 31 , R 32 are the same or different and represent H, an alkyl or alkoxy group having 1 to 15 C atoms, provided that one or more CH groups in these groups are not directly linked to O atoms, and are -C≡C-, -CF2O-, -OCF2-, -CH=CH-, [ka] It may be replaced by -O-, -CO-O- or -O-CO-, in which additionally one or more H atoms may be replaced by halogen.

[0118] The compound of formula III-3 is preferably selected from the group of compounds of formulae III-3-1 to III-3-10.

[0119] [ka]

[0120] [ka]

[0121] In the formula, R 32 is alkyl 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.

[0122] In a preferred embodiment of the invention the medium comprises one or more compounds of formulae III-4 to III-6, preferably of formula III-5.

[0123] [ka]

[0124] where the parameters have the meanings given above and R 31 preferably represents a linear alkyl having 1 to 7 C atoms, R 32 preferably denotes alkoxy having 1 to 7 C atoms.

[0125] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula III selected from the group of compounds of formulae III-7 to III-9, preferably of formula III-8.

[0126] [ka]

[0127] where the parameters have the meanings given above and R 31preferably represents a linear alkyl having 1 to 7 C atoms, R 32 preferably denotes alkoxy having 1 to 7 C atoms.

[0128] In a preferred embodiment, the medium comprises one or more compounds of formula IV.

[0129] [ka]

[0130] During the ceremony, R 41 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, preferably an n-alkyl group, particularly preferably having 2, 3, 4 or 5 C atoms, R 42 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkoxy group having 1 to 6 C atoms (both of which preferably have 2 to 5 C atoms), an unsubstituted alkenyl group having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably a vinyl group or a 1-propenyl group, in particular a vinyl group, However, compounds of formula I are excluded from formula IV and its subformulas.

[0131] The compound of formula IV is preferably selected from the group of compounds of formulae IV-1 to IV-4.

[0132] [ka]

[0133] During the ceremony, alkyl and alkyl' each independently represent an alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, alkenyl represents an alkenyl group having 2 to 5 C atoms, preferably 2 to 4 C atoms, particularly preferably 2 C atoms; alkenyl' represents an alkenyl group having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, Alkoxy represents alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0134] Preferably, the medium comprises one or more compounds selected from the compounds of formulae IV-1-1 to IV-1-4.

[0135] [ka]

[0136] Very preferably, the medium according to the invention comprises a compound of formula IV-1-1.

[0137] Very preferably, the medium according to the invention comprises one or more compounds of formula IV-2-1 and / or IV-2-2.

[0138] [ka]

[0139] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula IV-3:

[0140] [ka]

[0141] in which alkyl very preferably denotes an alkyl group having 1 to 7 C atoms, in particular n-ethyl or n-propyl, very particularly n-propyl, and alkenyl is [ka] wherein m is 0, 1 or 2, preferably 0; and n is 0, 1 or 2, preferably 0 or 1.

[0142] In particular it is selected from the compounds of the formulae IV-3-1 to IV-3-6, very particularly preferably of the formula IV-3-2.

[0143] [ka]

[0144] In a preferred embodiment, the medium comprises in particular, in addition to the compounds of the formulae IV-3-1 to IV-3-6, one or more compounds of the formulae IV-3-7 to IV-3-9.

[0145] [ka]

[0146] Preferably, the concentration of compounds of formulae IV-3-7 to IV-3-9 in the medium according to the invention is less than 5% or less than 4% or less than 3%, very preferably 0% to 1%, in particular 0%.

[0147] Highly preferably, the medium according to the invention comprises one or more compounds of formula IV-3 and one or more compounds of formula IV-1, with the proviso that the total concentration of compounds of formula IV-1 is in the range of 1% to 30%.

[0148] Very preferably, the medium according to the invention comprises a compound of the formula IV-4, in particular selected from the compounds of the formulae IV-4-1 to IV-4-3, in particular the compounds of the formula IV-4-3.

[0149] [ka]

[0150] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula I selected from the compounds of formulae I-1 to I-4 in combination with one or more compounds selected from the group of compounds of formulae IA-1 to IA-18.

[0151] [ka]

[0152] [ka]

[0153] In the formula, alkyl represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or n-pentyl.

[0154] The liquid crystal medium according to the invention preferably comprises one or more compounds of the formula IVa.

[0155] [ka]

[0156] During the ceremony, R 41 and R 42 each independently of one another represents a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkenyloxy group having up to 12 C atoms, and [ka] Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8-, or -CF=CF-.

[0157] Preferred compounds of formula IVa are shown below.

[0158] [ka]

[0159] During the ceremony, Alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 C atoms.

[0160] The medium according to the invention preferably comprises at least one compound of the formula IVa-1 and / or of the formula IVa-2, very preferably of the formula IVa-2, in particular alkyl, which is n-propyl and alkyl * represents methyl.

[0161] The proportion of compounds of formula IVa in the mixture as a whole is preferably less than 5% by weight, very preferably less than 2% by weight.

[0162] Preferably the medium comprises one or more compounds of formulae IVb-1 to IVb-3.

[0163] [ka]

[0164] During the ceremony, Alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 C atoms.

[0165] The proportion of compounds of the formulae IV-1 to IV-3 in the mixture as a whole is preferably less than 3% by weight, in particular less than 2% by weight.

[0166] Among the compounds of the formulae IVb-1 to IVb-3, the compound of the formula IVb-2 is particularly preferred.

[0167] Very particularly preferred are biphenyls.

[0168] [ka]

[0169] In the formula, alkyl *stands for an alkyl group having 1 to 6 C atoms, preferably for n-propyl or n-butyl. The medium according to the invention particularly preferably comprises one or more compounds of the formulae IVb-1-1 and / or IVb-2-3.

[0170] In the compounds of formula IVb-1-1, alkyl preferably represents propyl, butyl and pentyl, most preferably propyl.

[0171] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds of formula V

[0172] [ka]

[0173] During the ceremony, R 51 , R 52 represents an alkyl having 1 to 7 C atoms, an alkoxy having 1 to 7 C atoms, or an alkoxyalkyl, alkenyl, or alkenyloxy having 2 to 7 C atoms, [ka] represents Z 51 , Z 52 each independently represents -CH-CH-, -CH-O-, -CH=CH-, -C≡C-, -COO- or a single bond, and n is 1 or 2.

[0174] The compound of formula V is preferably selected from the compounds of formulae V-1 to V-17.

[0175] [ka]

[0176] [ka]

[0177] In the formula, R 51 and R 52 has the meaning given above in formula V. 51 and R 52 preferably, each independently represent a linear alkyl having 1 to 7 C atoms or an alkenyl having 2 to 7 C atoms.

[0178] Preferred media are one or more compounds of formula V-1, V-3, V-4, V-6, V-7, V-10, V-11, V-12, V-14, V-15, V-16 and / or V-17, very preferably V-16, in particular R 51 represents n-propyl, R 52 represents ethyl.

[0179] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of formula VI.

[0180] [ka]

[0181] In the formula, R 6 and R 62 is R as defined in claim 1 2A or R 62 represents F, Cl, CF3 or OCF3, preferably F; L 61 , L 62 , L 63 , L 64 , L 65 and L 66 each independently represents H or F, with the proviso that L 61 , L 62 , L 63 , L 64 , L 65 and L 66 At least one of the following represents F.

[0182] The compounds of formula VI are preferably selected from formulae VI-1 to VI-21, in particular formula VI-4.

[0183] [ka]

[0184] [ka]

[0185] [ka]

[0186] In the formula, R 6 represents a linear alkyl or alkoxy group having 1 to 6 C atoms, (O) represents -O- or a single bond, m is 0, 1, 2, 3, 4, 5 or 6, and n is 0, 1, 2, 3 or 4. R 6 preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.

[0187] Particularly preferred are the compounds of formulae VI-1, VI-2, VI-4, VI-20 and VI-21.

[0188] Very preferably, the medium according to the invention comprises a compound of formula IV-4, in particular a compound of formula IV-4-1.

[0189] [ka]

[0190] In the formula, R 6 and m has the meaning defined above, preferably R 6 represents methyl, ethyl, n-propyl, n-butyl or n-pentyl, and m is 2, 3, or 4.

[0191] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of formula VIA.

[0192] [ka]

[0193] In the formula, R 6 and R 62 is R as defined in claim 1 2A or R 62 represents F, Cl, CF3 or OCF3, preferably F; L 61 , L 62 , L 63 , L 64 , L 65 and L 66 each independently represents H or F, with the proviso that L 61 , L 62 , L 63 , L 64 , L 65 and L 66 At least one of represents F, Z 61 and Z 62 independently represent a single bond, -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO- or -CF2-O-, but Z 61 and Z 62 is not the same.

[0194] Very preferably, the medium according to the invention comprises a compound of formula VIA-1 and / or formula X.

[0195] [ka]

[0196] In the formula, R 6 and m has the meaning defined above, preferably R 6 represents methyl, ethyl, n-propyl, n-butyl or n-pentyl, and m is 2, 3, or 4. In a particularly preferred embodiment, R 6 represents n-propyl, and m represents 2.

[0197] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of the formulae VII-1 to VII-9.

[0198] [ka]

[0199] [ka]

[0200] During the ceremony, R 7 represents a linear alkyl or alkoxy group having 1 to 6 C atoms or a linear alkenyl group having 2 to 6 C atoms, and and w is an integer from 1 to 6.

[0201] Particularly preferred are mixtures containing at least one compound of formula VII-9.

[0202] Further preferred embodiments are listed below.

[0203] a) A liquid-crystalline medium comprising at least one compound of the formulae Z-1 to Z-8.

[0204] [ka]

[0205] where R is R in formula IIA 2A where alkyl denotes a straight-chain alkyl group having 1 to 6 C atoms. In a preferred embodiment the liquid-crystalline medium according to the invention comprises at least one compound of the formula Z-8.

[0206] b) Preferred liquid crystal media according to the invention comprise one or more substances which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, the compounds of the formulae N-1 to N-5.

[0207] [ka]

[0208] R in the formula 1N and R 2N are each independently R 2A and preferably represents straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, Z 1 and Z 2 each independently represents -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH=CH-, -CHO-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond.

[0209] c) Preferred mixtures comprise one or more compounds selected from the group of the difluorodibenzochroman compounds of formula BC, the chromans of formula CR and the fluorinated phenanthrenes of formulae PH-1 and PH-2.

[0210] [ka]

[0211] During the ceremony, R B1 , R B2 , R CR1 , R CR2 , R 1 , R 2 are each independently R 2A where c is 0, 1 or 2. 1 and R 2 preferably each independently denote alkyl or alkoxy having 1 to 6 C atoms.

[0212] Particularly preferred compounds of formulae BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5.

[0213] [ka]

[0214] [ka]

[0215] During the ceremony, Alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 C atoms, alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 C atoms.

[0216] Very particular preference is given to mixtures comprising one, two or three compounds of the formulae BC-2, BF-1 and / or BF-2.

[0217] d) Preferred mixtures contain one or more indane compounds of formula In.

[0218] [ka]

[0219] During the ceremony, R 11 , R 12 and R 13 each independently represents a linear alkyl, alkoxy, alkoxyalkyl or alkenyl group having 1 to 6 C atoms, R 12 and R 13 represents a halogen, preferably F, [ka] represents i represents 0, 1 or 2.

[0220] Preferred compounds of formula In are compounds of formulae In-1 to In-16 shown below.

[0221] [ka]

[0222] [ka]

[0223] [ka]

[0224] Particularly preferred are the compounds of formulae In-1, In-2, In-3 and In-4.

[0225] e) Preferred mixtures additionally contain one or more compounds of the formulae L-1 to L-5.

[0226] [ka]

[0227] [ka]

[0228] [ka]

[0229] During the ceremony, R, R 1 and R 2 are each independently R in formula IIA above. 2A where alkyl represents an alkyl group having 1 to 6 C atoms. The parameter s represents 1 or 2.

[0230] The compounds of the formulae L1 to L9 are preferably used in concentrations of 5 to 15% by weight, in particular 5 to 12% by weight, very particularly preferably 8 to 10% by weight.

[0231] f) Preferred mixtures additionally contain one or more compounds of formula IIA-Y.

[0232] [ka]

[0233] R in the formula 11 and R 12 is the above formula IIA, R 2A has one of the meanings given to L 1 and L 2 are the same or different and represent F or Cl; L 3 represents H or CH3.

[0234] Preferred compounds of formula IIA-Y are selected from the group consisting of the following subformulae:

[0235] [ka]

[0236] [ka]

[0237] In the formula, alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 C atoms, alkoxy represents a linear alkoxy group having 1 to 6 C atoms, alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 C atoms, and O represents an oxygen atom or a single bond. *preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0238] Particularly preferred compounds of formula IIA-Y are selected from the group consisting of the following subformulae:

[0239] [ka]

[0240] In the formula, alkoxy and alkoxy * has the meaning defined above and preferably denotes methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy.

[0241] g) The medium additionally comprises one or more compounds selected from the compounds of formulae P-1 to P-4.

[0242] [ka]

[0243] During the ceremony, R P represents a linear alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms, X P represents linear alkyl having 1 to 6 C atoms, F, Cl, CF3, OCF2H, OCF3, OCHFCF3, OCF2CHFCF3, OCH=CF2, preferably F, OCF3 or CF3, CH3, L P1 , L P2 and L P3 each independently represents H or F.

[0244] Preferred compounds of formulae P1 to P4 are listed below.

[0245] [ka]

[0246] In the formula, R P has the meaning given above. Preferably R P represents alkyl or alkenyl, in particular ethyl, propyl, butyl, pentyl, 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-, and alkyl represents a straight-chain alkyl group having 1 to 6 carbon atoms.

[0247] h) In a preferred embodiment, the mixture according to claim 1 comprises at least one compound selected from the group of compounds of the formulae IIA-18, IIA-42, IIA-49, IIA-51, IIA-52, IID-4, IID-10, III-3, III-4, IIIA-1-3, IVb-1, IV-b-2, VIA-1, X, V-11, V-17, Z-8 and IIA-Y.

[0248] Preferably, the medium according to the invention comprises one compound of formula H.

[0249] [ka]

[0250] During the ceremony, Ar represents an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms, preferably having 6 to 30 C atoms; Sp represents a spacer group; R S represents H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms; Z S are -O-, -C(O)O-, -(CH2) z -or-(CH2) zO-, or a single bond; HA is [ka] represents; R H H, O · , CH3, OH or OR S , preferably H or O · represents; R S1 , R S2 , R S3 and R S4 are identical or different and represent alkyl having 1 to 6 C atoms, preferably having 1 to 3 C atoms, very preferably CH3; G is H or R S or group Z S - represents HA; z is an integer from 1 to 6; and q is 3 or 4.

[0251] In formula H, aryl preferably represents an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms, containing 1, 2, 3 or 4 aromatic rings, including fused rings which may be linked directly or via an alkylene linking group having 1 to 12 C atoms, with the proviso that one or more H atoms may be replaced by alkyl or alkoxy having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms, or CN, CF3 or halogen, with the proviso that one or more CH2 groups may be replaced by -O-, -S-, -NH-, -N(C1-C4-alkyl)-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C-, each independently of the other, such that the O or S atoms are not directly linked to each other.

[0252] Preferred aryl groups are benzene, naphthalene, anthracene, biphenyl, m-terphenyl, p-terphenyl and (phenylalkyl)benzene, where alkyl is a straight-chain alkyl having 1 to 12 C atoms.

[0253] Compounds of formula H are described in EP-A-3354710 and EP-A-3354709.

[0254] The compound of formula H is preferably selected from the compounds of formulae H-1, H-2 and H-3.

[0255] [ka]

[0256] [ka]

[0257] In the formula, R H has the meaning given above and is preferably H or O · represents n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7; Sp represents a spacer group, preferably an alkylene having 1 to 12 C atoms in which one or more non-adjacent -CH2- groups may be replaced by -O-.

[0258] Preferred compounds of formula H-1 are selected from compounds of formula H-1-1:

[0259] [ka]

[0260] In the formula, R H has the meaning given above, preferably H or O · where n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, and most preferably 7.

[0261] Preferred compounds of formula H-2 are selected from compounds of formula H-2-1:

[0262] [ka]

[0263] In the formula, R H has the meaning given above, preferably H or O · represents n2 is the same or different in each occurrence, preferably the same and an integer from 1 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3; R S is identical or different at each occurrence, preferably identical and represents alkyl having 1 to 6 C atoms, preferably n-butyl.

[0264] Preferred compounds of formula H-3 are selected from compounds of formula H-3-1:

[0265] [ka]

[0266] In the formula, R H has the meaning given above, preferably H or O · represents n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, and most preferably 7.

[0267] Preferably, the medium according to the invention comprises a compound selected from the group of compounds of formulae ST-1 to ST-18.

[0268] [ka]

[0269] [ka]

[0270] [ka]

[0271] [ka]

[0272] During the ceremony R ST represents H, an alkyl or alkoxy group having 1 to 15 C atoms, provided that in addition, one or more CH groups in these groups are not directly linked to O atoms, and are -C≡C-, -CF2O-, -OCF2-, -CH=CH-, [ka] -O-, -CO-O-, -O-CO-, each independently of the other, in which one or more H atoms may be replaced by halogen; [ka] may be the same or different in each occurrence, [ka] represents Z ST represent, independently of one another, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CHO-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-, -CHO-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond; L 1 and L 2 each independently represents F, Cl, CH3, CF3 or CHF2, p represents 0, 1 or 2; q represents 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0273] Of the compounds of formula ST, the compounds of formulae ST-1 and ST-3 and especially the following are particularly preferred:

[0274] [ka]

[0275] [ka]

[0276] [ka]

[0277] In the compounds of formulae ST-3a and ST-3b, n preferably represents 3. In the compounds of formula ST-2a, n preferably represents 7.

[0278] Very particularly preferred mixtures according to the invention comprise one or more stabilizers from the group of compounds of the formulae ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1, ST-12.

[0279] [ka]

[0280] [ka]

[0281] The compounds of the formulae S and ST-1 to ST-19 are preferably present in the liquid crystal mixtures according to the invention in an amount of 0.005 to 0.5%, respectively, based on the mixture.

[0282] If the mixture according to the invention comprises two or more compounds from the group of compounds of formulae ST-1 to ST-18, the concentrations increase correspondingly to 0.01 to 1% for two compounds, based on the mixture.

[0283] However, the total proportion of compounds of the formulae ST-1 to ST-18, based on the mixture according to the invention, preferably does not exceed 2%.

[0284] The medium according to the invention preferably has a negative dielectric anisotropy.In a preferred embodiment the medium additionally comprises one or more compounds.

[0285] The term "reliability" as used herein refers to the quality of a display's performance over time under different stress loads such as light load, temperature, humidity, voltage, and display effects such as image sticking (area and line image sticking), mura, smearing, etc., known to those skilled in the art of liquid crystal displays. As a standard parameter to classify reliability, the voltage holding ration (VHR) value is usually used, which is a measure of the maintenance of a constant electrical voltage in a test display. A high VHR is a prerequisite for a reliable LC medium.

[0286] Hereinafter, unless otherwise specified, the term "PSA" is used to refer to polymer-sustained alignment displays in general, and the term "PS" is used to refer to specific display modes such as PS-VA and PS-TN.

[0287] Unless otherwise indicated, the term "RM" is also used hereinafter to refer to a polymerizable mesogenic compound or a polymerizable liquid crystal compound.

[0288] As used herein, the terms "active layer" and "switchable layer" refer to a layer in an electro-optical display, e.g. an LC display, that contains one or more types of molecules with structural and optical anisotropy, e.g. LC molecules, that undergo a change in molecular orientation upon application of an external stimulus, such as an electric or magnetic field, resulting in a change in the transparency of the layer for polarized or unpolarized light.

[0289] As used herein, the terms "tilt" and "tilt angle" are understood to mean the tilted orientation of the LC molecules of the LC medium in an LC display (herein preferably a PSA display) relative to the cell surface. In this specification, tilt angle means the average angle (less than 90°) between the molecular long axis (LC director) of the LC molecules and the surface of the flat parallel outer plates forming the LC cell. In this specification, low values ​​of tilt angle (i.e., large deviation from the angle 90°) correspond to large tilt. A suitable method for measuring the tilt angle is given in the examples. Unless otherwise indicated, the values ​​of tilt angle disclosed above and below refer to this measurement method.

[0290] As used herein, the terms "reactive mesogen" and "RM" are understood to mean a compound containing a mesogenic or liquid crystal backbone and one or more functional groups attached to the backbone suitable for polymerization, which functional groups are also referred to as "polymerizable groups" or "P".

[0291] As used herein, unless otherwise stated, the term "polymerizable compound" is understood to mean a polymerizable monomeric compound.

[0292] As used herein, the term "low molecular weight compound" is understood as a term in contrast to "polymeric compound" or "polymer" to mean a compound that is monomeric and / or not prepared by a polymerization reaction.

[0293] As used herein, the term "non-polymerizable compound" is understood to mean a compound that does not contain any functional group suitable for polymerization under the conditions normally applied for the polymerization of RMs.

[0294] As used herein, the term "mesogenic group" refers to a group known to those skilled in the art and described in the literature, which essentially contributes to the generation of a liquid-crystalline (LC) phase in low molecular weight or polymeric substances due to the anisotropy of its attractive and repulsive interactions. A compound containing a mesogenic group (mesogenic compound) does not necessarily have an LC phase by itself. It is also possible that a mesogenic compound exhibits LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod-like or disc-like shaped units. A review of the terms and definitions used in relation to mesogens or LC compounds is given in Pure Appl.Chem. 2001, Vol. 73 (No. 5), p. 888 and C. Tschierske, G. Pelzl, S. Diele, Angew.Chem. 2004, Vol. 116, p. 6340-6368.

[0295] As used herein, the terms "optically active" and "chiral" are synonymous for a material that can induce a helical pitch in a nematic host material, also referred to as a "chiral dopant."

[0296] As used herein, the term "spacer group", hereafter also referred to as "Sp", is known to those skilled in the art and described in the literature, see for example Pure Appl.Chem. 2001, vol. 73 (no. 5), p. 888 and C. Tschierske, G. Pelzl, S. Diele, Angew.Chem. 2004, vol. 116, p. 6340-6368. As used herein, the term "spacer group" or "spacer" refers to a flexible group, such as an alkylene group, that connects the mesogenic group and the polymerizable group(s) in a polymerizable mesogenic compound.

[0297] Throughout this patent application, 1,4-cyclohexylene and 1,4-phenylene rings are represented as follows: [ka]

[0298] The cyclohexylene ring is a trans-1,4-cyclohexylene ring.

[0299] Above and below, [ka] represents a trans-1,4-cyclohexylene ring.

[0300] basis [ka] The single bond shown between two ring atoms in can be attached to any non-bonded position of the benzene ring.

[0301] Above and below, "organic group" represents a carbon or hydrocarbon group.

[0302] The term "carbon group" refers to a monovalent or polyvalent organic group containing at least one carbon atom, provided that it either does not contain any additional type of atom (e.g., -C≡C-, etc.) or it may contain one or more additional types of atoms, such as, for example, N, O, S, B, P, Si, Se, As, Te, or Ge (e.g., carbonyl, etc.). The term "hydrocarbon group" refers to a carbon group that additionally contains one or more H atoms and may contain one or more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Te, or Ge.

[0303] "Halogen" represents F, Cl, Br or I, preferably F or Cl.

[0304] -CO-, -C(=O)- and -C(O)- are carbonyl groups, i.e. [ka] Represents.

[0305] The carbon or hydrocarbon group may be saturated or unsaturated. The unsaturated group may be, for example, an aryl, alkenyl or alkynyl group. The carbon or hydrocarbon group having more than three C atoms may be linear, branched and / or cyclic, and may contain spiro-linked or fused rings.

[0306] The terms "alkyl", "aryl", "heteroaryl", etc. also include polyvalent groups, such as alkylene, arylene, heteroarylene, etc. 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).

[0307] In this specification, alkyl is linear or branched and has 1 to 15 C atoms, preferably linear and, unless otherwise indicated, has 1, 2, 3, 4, 5, 6 or 7 C atoms and is therefore preferably methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl.

[0308] As used herein, branched alkyl is alkyl having secondary and / or tertiary, preferably secondary, carbon atoms, and is preferably isopropyl, sec-butyl, isobutyl, isopentyl, 2-methylhexyl or 2-ethylhexyl, 2-methylpropyl, 2-pentyl, 3-pentyl, 2-methylbutyl, 3-methylbutyl.

[0309] In this specification, a cyclic alkyl group is intended to mean a cyclic aliphatic or alkyl group in which a methylene group is replaced by a cyclic aliphatic group (i.e., cycloalkylalkyl or alkylcycloalkylalkyl), which may be saturated or partially unsaturated, and preferably represents cyclopropyl, methylcyclopropyl, cyclobutyl, methylcyclobutyl, cyclopentyl, methylcyclopentyl, cyclopent-1-enyl, cyclopropylmethyl, cyclopropylethyl, cyclobutylmethyl, cyclobutylethyl, cyclopentylmethyl, cyclopentylethyl, cyclopent-1-enylmethyl.

[0310] In the present specification, alkoxy groups are linear or branched and contain 1 to 15 C atoms, preferably linear and, unless otherwise indicated, have 1, 2, 3, 4, 5, 6 or 7 C atoms, and therefore are preferably methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexoxy or n-heptoxy.

[0311] In the present specification, an alkenyl group is preferably an alkenyl group having 2 to 15 C atoms, being linear or branched and containing at least one CC double bond. It is preferably linear and has 2 to 7 C atoms. It is therefore preferably vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl. If two C atoms of the CC double bond are substituted, the alkenyl group may be in the form of E and / or Z isomers (trans / cis). In general, the respective E isomer is preferred. Among the alkenyl groups, prop-2-enyl, but-2- and -3-enyl and pent-3- and -4-enyl are particularly preferred.

[0312] In the present specification, alkynyl is taken to mean an alkynyl group having 2 to 15 C atoms, which is linear or branched and contains at least one C-C triple bond. 1- and 2-propynyl and 1-, 2- and 3-butynyl are preferred.

[0313] Preferred carbon and hydrocarbon groups are optionally substituted linear, branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy having 1 to 40, preferably 1 to 20, particularly preferably 1 to 12 C atoms, optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to 25 C atoms, or optionally substituted alkylaryl, arylalkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to 25 C atoms, with the proviso that one or more C atoms may be replaced by a heteroatom, preferably selected from N, O, S, Se, Te, Si and Ge.

[0314] More preferred carbon and hydrocarbon groups are C1-C 20 Alkyl, C2-C 20 Alkenyl, C2-C 20 Alkynyl, C3-C 20 Allyl, C4~C 20 Alkyldienyl, C4-C 20 Polyenyl, C6-C 20 Cycloalkyl, C4-C 15 Cycloalkenyl, C6-C 30 Aryl, C6-C 30 Alkylaryl, C6-C 30 Aryl alkyl, C6-C 30 Alkylaryloxy, C6-C 30 Arylalkyloxy, C2-C 30 Heteroaryl, C2-C 30 It is heteroaryloxy.

[0315] C1~C 12 Alkyl, C2-C 12 Alkenyl, C2-C 12 Alkynyl, C6-C 25 Aryl and C2-C 25 Heteroaryl is especially preferred.

[0316] Further preferred carbon and hydrocarbon groups are alkyl, linear, branched or cyclic, having 1 to 20, preferably 1 to 12, C atoms, which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN, with the proviso that one or more non-adjacent CH groups are each independently of one another -C(R x )=C(R x )-, -C≡C-, -N(R x ) -, -O-, -S-, -CO-, -CO-O-, -O-CO-, or -O-CO-O-.

[0317] R x preferably represents H, F, Cl, CN, a linear, branched or cyclic alkyl chain having 1 to 25 C atoms (with the proviso that in addition, one or more non-adjacent C atoms may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, with the proviso that 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.

[0318] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl, s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, and the like.

[0319] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, and the like.

[0320] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl and the like.

[0321] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy, n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, and the like.

[0322] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, and the like.

[0323] Aryl and heteroaryl groups may be monocyclic or polycyclic, i.e., they may contain one ring (such as phenyl) or two or more rings, and the groups may be fused (such as naphthyl) or covalently linked (such as biphenyl) or may contain a combination of fused and linked rings. Heteroaryl groups preferably contain one or more heteroatoms selected from O, N, S and Se.

[0324] Particularly preferred are monocyclic, bicyclic or tricyclic aryl groups having 6 to 25 C atoms and monocyclic, bicyclic or tricyclic heteroaryl groups having 5 to 25 ring atoms, which may contain fused rings and may be substituted.Furthermore, 5-, 6- or 7-membered aryl and heteroaryl groups are preferred, provided that in addition, one or more CH groups may be replaced by N, S or O, in such a way that the O and / or S atoms are not directly linked to one another.

[0325] Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1,1':3',1"]terphenyl-2'-yl, naphthyl, anthracene, binaphthyl, phenanthrene, 9,10-dihydrophenanthrene, pyrene, dihydropyrene, chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, and the like.

[0326] Preferred heteroaryl groups are, for example, 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- Five-membered rings such as thiadiazole, 1,2,5-thiadiazole, and 1,3,4-thiadiazole; six-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, and 1,2,3,5-tetrazine; or indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, pristine, , naphthaimidazole, phenanthroimidazole, pyridaimidazole, pyrazineimidazole, quinoxalineimidazole, benzoxazole, naphthoxazole, anthroxazole, phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzoi Condensed groups such as isoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazothiophene, or a combination of these groups.

[0327] The aryl and heteroaryl groups mentioned above and below may also be substituted with alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or further aryl or heteroaryl groups.

[0328] (Non-aromatic) alicyclic and heterocyclic groups include both saturated rings, i.e. those containing exclusively single bonds, and also partially unsaturated rings, i.e. those which may also contain multiple bonds. Heterocyclic rings preferably contain one or more heteroatoms selected from Si, O, N, S and Se.

[0329] (Non-aromatic) alicyclic and heterocyclic groups may be monocyclic, i.e. containing only one ring (e.g. cyclohexane) or polycyclic, i.e. containing several rings (e.g. decahydronaphthalene or bicyclooctane). Saturated groups are particularly preferred. Furthermore, monocyclic, bicyclic or tricyclic groups having 5 to 25 ring atoms are preferred, which may contain fused rings and may be substituted. Furthermore, 5-, 6-, 7- or 8-membered carbocyclic groups are preferred, provided that in addition, one or more C atoms may be replaced by Si and / or one or more CH groups may be replaced by N and / or one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-.

[0330] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran, pyrrolidine, 6-membered groups such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine, 7-membered groups such as cycloheptane, and fused groups such as tetrahydronaphthalene, decahydronaphthalene, indane, bicyclo[1.1.1]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.

[0331] Preferred substituents are solubility-promoting groups such as, for example, alkyl or alkoxy, electron-withdrawing groups such as fluorine, nitro or nitrile, or substituents for increasing the glass transition temperature (Tg) in the polymer, especially bulky groups such as, for example, t-butyl or optionally substituted aryl groups.

[0332] Preferred substituents are also referred to hereinafter as "L" and include, for example, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, linear or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 25 C atoms (wherein one or more H atoms may be replaced by F or Cl), optionally substituted silyl having 1 to 20 Si atoms, or optionally substituted aryl having 6 to 25, preferably 6 to 15, C atoms.

[0333] In the formula, R x represents H, F, Cl, CN, a linear, branched or cyclic alkyl chain having 1 to 25 C atoms, with the proviso that one or more non-adjacent CH2 groups may be 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 linked to one another, with the proviso that one or more H atoms may be replaced by F, Cl, P- or P-Sp-, respectively;

[0334] and Y 1 represents a halogen.

[0335] The "substituted silyl or aryl" is preferably a halogen, -CN, R 0 , -OR 0 , -CO-R 0 , -CO-OR 0 , -O-CO-R 0OR-O-CO-OR 0 where R 0 represents H or alkyl having 1 to 20 C atoms.

[0336] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and also phenyl.

[0337] To produce a PSA display, polymerizable compounds contained in the LC medium are polymerized or crosslinked (if a compound contains more than one polymerizable group) by in situ polymerization in the LC medium between the substrates of the LC display, optionally with application of a voltage to the electrodes.

[0338] The structure of the PSA display according to the invention corresponds to the usual structure of the PSA display as described in the prior art cited at the beginning. A structure without protrusions is preferred, in particular in which the electrode on the color filter side is not structured and only the electrode on the TFT side has slits. A particularly suitable and preferred electrode structure for PS-VA displays is described, for example, in US 2006 / 0066793 A1.

[0339] The LC media according to the invention may additionally comprise one or more further components or additives selected without limitation from the following list: comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, hydrophobizing agents, adhesives, flow improvers, antifoaming agents, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0340] The LC medium according to the invention preferably comprises one, two or three chiral dopants, very preferably one chiral dopant.

[0341] Particularly preferred are LC media which comprise one, two or three polymerisable compounds, also called reactive mesogens (RM).

[0342] Further preferred is an LC medium having a chiral nematic LC phase.

[0343] Preferably the proportion of polymerizable compound (RM) in the LC medium is between >0% and <5%, very preferably between >0% and <1%, most preferably between 0.01 and 0.5%.

[0344] Preferred embodiments, either alone or in combination with one another, are listed below. The medium according to the invention preferably comprises

[0345] a compound of formula I in a concentration ranging from 0.5% to 15%, preferably from 1% to 10%, very preferably from 2% to 7%;

[0346] one, two or more compounds of formula III, preferably of formula III-1 and / or III-2, more preferably of formula III-2, in a total concentration in the range from 2% to 15%, more preferably from 3% to 12%, very preferably from 4% to 10%, in particular from 5% to 8%;

[0347] one or more compounds of formula IIA in a total concentration in the range of 10% to 40%, more preferably 15% to 35%, very preferably 18% to 28% or 20% to 25%;

[0348] one or more compounds of formula IIA-2 in a total concentration in the range of 1% to 12%, more preferably 2% to 8%, very preferably 3% to 6%;

[0349] one or more compounds of formula IIA-10 in a total concentration in the range of 10% to 30%, more preferably 12% to 25%, very preferably 15% to 20%;

[0350] one or more compounds of formula IIB, preferably of formula IIB-2 and / or IIB-10, in a total concentration in the range from 10% to 30%, more preferably from 12% to 25%, very preferably from 14% to 19%;

[0351] one or more compounds of formula IIB-2 in a total concentration in the range of 1% to 12%, more preferably 2% to 8%, very preferably 3% to 6%;

[0352] one or more compounds of formula IIB-10 in a total concentration in the range of 5% to 25%, more preferably 8% to 18%, very preferably 10% to 15%;

[0353] one or more compounds of formula IIA and one or more compounds of formula IIB, preferably selected from formulae IIA-2, IIA-10, IIB-2 and IIB-10, in a total concentration preferably in the range of 25% to 55%, more preferably 32% to 50%, very preferably 35% to 42%;

[0354] one or more compounds of formula IIA-2 and one or more compounds of formula IIB-2 in a combined concentration in the range of 3% to 20%, more preferably 4% to 15%, very preferably 6% to 11%;

[0355] one or more compounds of formula III and one or more compounds selected from formulae IIA, IIB, IIC and IID in a total concentration in the range of 25% to 65%, more preferably 35% to 55%, very preferably 40% to 50%;

[0356] one or more compounds of formula IV-1, preferably compound IV-1-1, in a total concentration in the range of 5% to 40%, more preferably 10% to 30%, very preferably 15% to 23%;

[0357] one or more compounds of formula IV-3, preferably of formula IV-3-2 and / or IV-3-5, in a total concentration in the range of 5% to 25%, more preferably 10% to 20%, very preferably 12% to 16%;

[0358] one or more compounds of formula I and a compound of formula IV-3-2 in a total concentration in the range of 3% to 20%, more preferably 6% to 15%, very preferably 8% to 12%;

[0359] one or more compounds of formula I and compounds of formula IV-3-2 and compounds of formula IV-1-1 in a total concentration in the range from 15% to 45%, more preferably from 22% to 40%, very preferably from 26% to 34%, in particular from 28% to 32%;

[0360] Compound of formula IV-3-6 in a total concentration in the range of 0% to 5%, preferably 0%;

[0361] one or more compounds of formula I and one or more compounds selected from formulae IV and IVa in a total concentration in the range of 20% to 50%, more preferably 28% to 45%, very preferably 33% to 40%;

[0362] one or more compounds of formula I and one or more compounds selected from formulae IV and IVa and one or more compounds of formula V in a total concentration in the range of 35% to 60%, more preferably 38% to 52%, very preferably 40% to 48%;

[0363] one or more compounds of formula IVa and / or IVb in a total concentration in the range of 5% to 18%, more preferably 7% to 15%, very preferably 8% to 13%;

[0364] one or more compounds of formula V, preferably of formula V-16, in a total concentration in the range of 1% to 12%, more preferably 2% to 10%, even more preferably 3% to 10%, very preferably 4% to 8% Includes.

[0365] Particularly preferred mixture concepts are given below (the acronyms used are explained in Tables A to D, where n and m each independently represent 1 to 6):

[0366] The mixture according to the invention is preferably

[0367] PYP-nm, in particular PYP-2-3 and / or PYP-2-4, preferably in a concentration of more than 5%, in particular 8-30%, relative to the total mixture,

[0368] and / or CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably at a concentration of more than 5%, in particular 10-30%, relative to the total mixture,

[0369] and / or B-nO-Om and / or B(S)-nO-Om, preferably in a concentration of 1 to 15,

[0370] and / or CY-n-Om, preferably CY-3-O2, CY-3-O4, CY-5-O2 and / or CY-5-O4, preferably in a concentration of more than 5%, in particular 15-50%, relative to the total mixture,

[0371] and / or CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably in a concentration of more than 5% and in particular 10-30% relative to the total mixture,

[0372] and / or CLY-n-Om, preferably CLY-2-O4, CLY-3-O2 and / or CLY-3-O3, preferably at a concentration of more than 5%, in particular 10-30%, relative to the total mixture,

[0373] and / or LY-n-Om, preferably LY-3-O2, preferably at a concentration of more than 5%, in particular 10-30%, relative to the total mixture,

[0374] and / or CCOY-n-Om, preferably CCOY-3-O2, in a concentration of preferably more than 5%, in particular 10-30%, relative to the total mixture,

[0375] and / or CLOY-n-Om, preferably CLOY-3-O2, preferably at a concentration of more than 5%, in particular 10-30%, relative to the total mixture,

[0376] CK-nF, preferably CK-3-F, CK-4-F and / or CK-5-F, preferably at a concentration of more than 5%, in particular 5-25%, relative to the total mixture,

[0377] and / or at least two compounds of the formula PY-n-Om, preferably PY-1-O2 and PY-3-O2 Includes.

[0378] Further preferred are mixtures according to the invention which include the following mixture concepts: (n and m each independently represent 1 to 6.)

[0379] CPY-n-Om and CY-n-Om, preferably at a concentration of 10-80% relative to the total mixture,

[0380] and / or CPY-n-Om and CK-nF, preferably at a concentration of 10-70% relative to the total mixture,

[0381] and / or CPY-n-Om and PY-n-Om, preferably CPY-2-O2 and / or CPY-3-O2 and PY-3-O2, preferably in a concentration of 10-40% relative to the total mixture,

[0382] and / or CPY-n-Om and CLY-n-Om, preferably at a concentration of 10-80% relative to the total mixture,

[0383] and / or CC-3-V1, preferably in an amount of 3-15%,

[0384] and / or PGIY-n-Om, preferably in an amount of 3-15%,

[0385] and / or · CC-n-2V1 preferably in an amount of 3-20%.

[0386] The liquid crystal media according to the invention advantageously have a nematic phase preferably at temperatures from -20°C to 70°C, particularly preferably from -30°C to 71°C and very particularly preferably from -40°C to 72°C.

[0387] In a preferred embodiment the medium according to the invention has a clearing temperature of 70°C or more, more preferably 72°C or more, in particular 73°C or more.

[0388] The expression "having a nematic phase" at a given temperature in this document means that at low temperatures no smectic phases and no crystallization are observed, while at the given temperature no clearing (transition to an isotropic phase) occurs upon heating of the nematic phase. The low temperature studies are carried out with a flow viscometer at the corresponding temperature and are confirmed by storage for at least 100 hours in test cells with layer thicknesses corresponding to the electro-optical application. If the storage stability in test cells at a temperature of -20°C is more than 1000 hours, the medium is called stable at this temperature. For temperatures of -30°C and -40°C, the corresponding times are 500 hours and 250 hours, respectively. At high temperatures, the clearing point is measured in a capillary tube in the conventional manner.

[0389] The liquid crystal mixture preferably has a nematic phase range of at least 60K and a maximum of 30mm at 20°C. 2 ·Seconds -1 Flow viscosity ν 20 has.

[0390] The mixture is nematic at temperatures below -20°C, preferably below -30°C, very preferably below -40°C.

[0391] The medium according to the present invention has a birefringence in the range of 0.085 to 0.120, preferably 0.095 to 0.115, in particular 0.100 to 0.110.

[0392] In a preferred embodiment, the medium has a birefringence in the range of 0.1005 to 0.1080, preferably 0.1020 to 0.1075, in particular 0.1035 to 0.1060.

[0393] In a preferred embodiment, the medium has a dielectric anisotropy Δε of −2.4 to −5.0, preferably −2.6 to −4.5, in particular −2.7 to −4.0.

[0394] In a very preferred embodiment the liquid crystal mixture according to the invention has a dielectric anisotropy Δε of −2.9 to −3.3.

[0395] The rotational viscosity γ1 at 20° C. is within a range of 70 to 200 mPa·s, and more preferably 90 to 150 mPa·s.

[0396] The rotational viscosity γ1 at 20° C. is preferably 100 mPa·s or less.

[0397] The medium according to the present invention has an elastic constant K1 in the range of 12 to 16 pN.

[0398] In a preferred embodiment, the medium according to the invention has a viscosity of 7.2 mPa·s·pN -1 The ratio of rotational viscosity to spray elastic constant γ1 / K1 is:

[0399] In a preferred embodiment, the medium according to the invention has a viscosity of 6.6 mPa·s·pN -1 ~7.4mPa·s·pN -1 , more preferably 6.9 mPa·s·pN -1 ~7.2 mPa s pN -1 The ratio of rotational viscosity to spray elastic constant γ1 / K1 is in the range of

[0400] The liquid-crystalline media according to the invention have relatively low values ​​of the threshold voltages (V0). They are preferably in the range from 1.7 V to 3.0 V, particularly preferably ≦2.6 V, very particularly preferably ≦2.4 V.

[0401] In the present invention, the term "threshold voltage" refers to the capacitive threshold (V0), also called the Friedericks threshold, unless otherwise specified.

[0402] In addition, the liquid-crystal media according to the invention have high values ​​of the voltage holding ratio in a liquid-crystal cell.

[0403] In general, liquid crystal media having a low addressing voltage or threshold voltage show a lower voltage holding ratio than those having a high addressing voltage or threshold voltage and vice versa.

[0404] In the present invention, the term "dielectrically positive compound" refers to a compound having a Δε greater than 1.5, the term "dielectrically neutral compound" refers to a Δε between -1.5 and 1.5, and the term "dielectrically negative compound" refers to a Δε smaller than -1.5. The dielectric anisotropy of the compound is determined by dissolving 10% of the compound in a liquid crystal host and measuring the capacitance of the resulting mixture at 1 kHz in at least one test cell with homeotropic and homogeneous surface alignment, respectively, with a layer thickness of 20 μm. The measuring voltage is typically between 0.5 V and 1.0 V, but always lower than the capacitance threshold of the respective liquid crystal mixture under consideration.

[0405] All temperature values ​​given in this invention are in °C.

[0406] The mixtures according to the invention are suitable for all VA-TFT applications, e.g. VAN, MVA, (S)-PVA, ASV, PSA (polymer sustained VA) and PS-VA (polymer stabilized VA). They are furthermore suitable for IPS (in-plane-switching) and FFS (fringe field switching) applications having a negative Δε.

[0407] It will be appreciated by those skilled in the art that the VA, IPS or FFS mixtures of the present invention may also contain compounds in which, for example, H, N, O, Cl and F are replaced by the corresponding isotopes.

[0408] The compounds according to the invention can be synthesized by known methods described in the literature (e.g. standard works such as Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart) or in a similar manner under known reaction conditions suitable for said reactions. Also, per se known variations can be used here, although not mentioned here. In particular, they can be prepared as described in the following reaction schemes or in a similar manner. Further methods for preparing the compounds of the invention can be taken from the examples.

[0409] Other mesogenic compounds not explicitly mentioned above can also be advantageously used in the medium according to the invention, such compounds being known to those skilled in the art.

[0410] In the present invention and the following examples, the structures of liquid crystal compounds are represented by acronyms, and the conversion to chemical formulas is performed according to the following Tables A to C. m H 2m+1 , C n H 2n+1 , and C l H 2l+1or C m H 2m-1 , C n H 2n-1 andC l H 2l-1 is a linear alkyl or alkylene radical with in each case n, m and l C atoms. Preferably, n, m and l are each independently 1, 2, 3, 4, 5, 6 or 7. Table A gives the codes of the ring elements of the nucleus of the compounds, Table B lists the bridging units and Table C lists the meaning of the symbols of the left and rightmost groups of the molecules. The acronyms consist of the code of the ring element with an optional linking group followed by the first hyphen and the code of the leftmost group and the second hyphen and the code of the rightmost group. Table D gives examples of the structures of the compounds with their respective abbreviations.

[0411] <Table A: Ring elements>

[0412] [Table 1]

[0413] [Table 2]

[0414] [Table 3]

[0415] <Table B: Cross-linking units>

[0416] [Table 4]

[0417] <Table C: Terminal group>

[0418] [Table 5]

[0419] In the table, n and m are each integers, and the three dots "..." are places for other abbreviations from this table.

[0420] Apart from the compounds of the formulae I, IIA, IIB, IIC and / or IID, IVa, IVb and V, the mixtures according to the invention preferably comprise one or more of the compounds mentioned below.

[0421] The following abbreviations are used: (n, m, k and l are each independently an integer, preferably 1 to 9, preferably 1 to 7, and k and l may be 0, preferably 0 to 4, more preferably 0 or 2, most preferably 2; n is preferably 1, 2, 3, 4 or 5; in the combination "-nO-", it is preferably 1, 2, 3 or 4, more 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".)

[0422]

[0423] [Table 6]

[0424] [Table 7]

[0425] [Table 8]

[0426] [Table 9]

[0427] [Table 10]

[0428]

Table 11

[0429]

Table 12

[0430]

Table 13

[0431]

Table 14

[0432]

Table 15

[0433]

Table 16

[0434]

Table 17

[0435]

Table 18

[0436]

Table 19

[0437]

Table 20

[0438] [Table 21]

[0439] [Table 22]

[0440] [Table 23]

[0441] Table E shows chiral dopants which are preferably employed in the mixtures according to the invention.

[0442]

[0443] [Table 24]

[0444] [Table 25]

[0445] [Table 26]

[0446] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds selected from the group of compounds from Table E.

[0447] Table F shows exemplary compounds which may preferably be used as reactive mesogenic compounds in the LC media according to the invention. If the mixture according to the invention comprises one or more reactive compounds, they are preferably employed in an amount of 0.01 to 5% by weight. It may also be necessary to add an initiator or a mixture of two or more initiators for the polymerization. The initiator or initiator mixture is preferably added in an amount of 0.001 to 2% by weight, based on the mixture. Suitable initiators are for example Irgacure (BASF) or Irganox (BASF).

[0448] [Table 27]

[0449] [Table 28]

[0450] [Table 29]

[0451] [Table 30]

[0452] [Table 31]

[0453] [Table 32]

[0454] [Table 33]

[0455] [Table 34]

[0456]

Table 35

[0457]

Table 36

[0458]

Table 37

[0459]

Table 38

[0460]

Table 39

[0461]

Table 40

[0462]

Table 41

[0463]

Table 42

[0464]

Table 43

[0465]

Table 44

[0466] [Table 45]

[0467] [Table 46]

[0468] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulae RM-1 to RM-102. This type of medium is particularly suitable for PS-FFS and PS-IPS applications. Among the reactive mesogens shown in table D, the compounds RM-1, RM-2, RM-3, RM-4, RM-5, RM-9, RM-17, RM-42, RM-48, RM-68, RM-87, RM-91, RM-98, RM-99 and RM-101 are particularly preferred.

[0469] The reactive mesogens or polymerizable compounds of the formula M and of the formulae RM-1 to RM-102 are furthermore suitable as stabilizers, in which case the polymerizable compounds are not polymerized but instead added to the liquid-crystalline medium in a concentration of more than 1%. EXAMPLES

[0470] The invention will now be described in detail by the following non-limiting examples.

[0471] The following abbreviations and symbols are used: V0 is the capacitance threshold voltage at 20°C [V]. n e is the extraordinary refractive index at 20°C and 589 nm, n0 is the normal refractive index at 20°C and 589 nm; Δn is the optical anisotropy at 20 °C and 589 nm; ε ⊥ is the dielectric constant perpendicular to the director at 20°C and 1 kHz, ε ∥ is the dielectric constant parallel to the director at 20°C and 1 kHz, Δε is the dielectric anisotropy at 20°C and 1 kHz. cl.p., T(N,I) is the clearing point [℃], γ1 is the rotational viscosity at 20℃ [mPa s], K1 is the elastic constant for "splay" deformation at 20°C [pN], K2 is the elastic constant for "twist" deformation at 20°C [pN], K3 is the elastic constant for "bend" deformation at 20°C [pN].

[0472] Unless expressly stated otherwise, all concentrations in this application are quoted in weight percent and refer to the corresponding mixture as a whole of all solid or liquid crystal components, without solvent.

[0473] Unless explicitly stated otherwise, all temperature values ​​given in this application, such as the melting point T(C,N), the transition from the smectic (S) phase to the nematic (N) phase T(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (°C). Mp is the melting point and cl.p. is the clearing point. Furthermore, C is the crystalline state, N is the nematic phase, S is the smectic phase and I is the isotropic phase. The data between these symbols represent the transition temperatures.

[0474] All physical properties are determined or have been determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", November 1997, Merck KGaA, Germany, and apply for a temperature of 20° C., with Δn being determined at 589 nm and Δε at 1 kHz, unless explicitly indicated otherwise in each case.

[0475] The term "threshold voltage" for the present invention, unless otherwise specified, relates to the capacitive threshold (V0), also known as the Freedericks threshold. Also, in the examples, and as is generally customary, the threshold voltage is set to 10% relative contrast (V 10 ) may also be indicated.

[0476] Unless otherwise specified, the method for preparing the test cells and the method for measuring the electro-optical properties, etc. are carried out according to the method described below or a similar method.

[0477] The display used to measure the capacitive threshold voltage consists of two plane-parallel glass outer plates spaced 25 μm apart, each with an electrode layer on its inner side and an unrubbed polyimide alignment layer on top that provides homeotropic alignment of the liquid crystal molecules.

[0478] Unless otherwise indicated, VHR is at 20°C (VHR 20 ) and after 5 min in a 100°C oven (VHR 100 ) on an instrument model LCM-1 (O0004) commercially available from Toyo Corporation, Japan. Unless expressly stated more precisely, the voltages used have frequencies within the range of 1 Hz to 60 Hz.

[0479] The stability against UV irradiation is investigated with "Suntest CPS+" by Heraeus GmbH, Germany, using a xenon lamp NXE1500B. The sealed test cells are irradiated for 2.0 h without additional heating unless explicitly stated. The irradiation power in the wavelength range from 300 nm to 800 nm is 765 W / m 2 V. To simulate the so-called window pane mode, a UV "cut-off" filter with an edge wavelength of 310 nm is used. For each condition in each experimental series, at least four test cells are considered and each result is presented as the average value of the corresponding individual measurements.

[0480] To study low-temperature stability, also known as "LTS" (low-temperature stability), i.e. the stability of LC mixtures in bulk against spontaneous crystallization of the individual components or the development of smectic phases at low temperatures, several sealed bottles, each containing about 1 g of material, are stored at one or more defined temperatures, typically -10°C, -20°C, -30°C and / or -40°C, and visually inspected at regular intervals to see if a phase transition is observed. The time is recorded when the first single sample at a defined temperature shows a change. The time until the last inspection, at which no change is observed, is recorded as the respective LTS.

[0481] The ion density for calculating resistivity is measured using a commercially available LC Material Property Measurement System Model 6254 from Toyo Corporation, Japan, using a VHR test cell with AL16301 polyimide (JSR Corporation, Japan) and a cell gap of 3.2 μm. Measurements are taken after storage in an oven at 60°C or 100°C for 5 min.

[0482] The clearing point is measured using a Mettler Thermosystem FP900. The optical anisotropy (n) is measured using an Abbe refractometer H005 (sodium spectrum lamp Na10, 589 nm, at 20°C). The dielectric anisotropy (Δε) is measured using an LCR meter E4980A / Agilent (G005) at 20°C (ε-parallel cell with JALS2096-R1). The starting voltage (V0) is measured using an LCR meter E4980A / Agilent (G005) at 20°C (ε-parallel cell with JALS2096-R1). The rotational viscosity (γ1) is measured using a Toyo Corporation LCM-2 (0002) at 20°C (gamma 1 negative cell with JALS-2096-R1). Elastic constant (K1, splay) is measured at 20°C using LCR meter E4980A / Agilent (G005) (ε-parallel cell with JALS2096-R1). K3: Elastic constant (K3, bend) is measured at 20°C using LCR meter E4980A / Agilent (G005) (ε-parallel cell with JALS2096-R1).

[0483] The following example mixtures with negative dielectric anisotropy are particularly suitable for liquid crystal displays with at least one planar alignment layer, such as, for example, IPS and FFS displays, in particular UB-FFS (: Ultra Bright FFS), and also VA displays.

[0484] <Mixture example> The nematic LC host mixtures M1-M9 have the compositions and physical properties given in the table below.

[0485] <Mixture M1>

[0486] [Table 47]

[0487] <Mixture M2>

[0488] [Table 48]

[0489] <Mixture M3>

[0490] [Table 49]

[0491] Mixture M4 contains compound B(S)-2O-O1(c5).

[0492] [ka]

[0493] <Mixture M4>

[0494] [Table 50]

[0495] Mixture M5 contains the following compound CPY-(c3)2-O2:

[0496] [ka]

[0497] <Mixture M5>

[0498] [Table 51]

[0499] <Mixture M6> Mixture M6 consists of 98.87% of mixture M1, 0.03% of compound ST-3a-1 and 0.10% of compound H-1-1.

[0500] [ka]

[0501] <Mixture M7> Mixture M7 consists of 98.965% of mixture M1, 0.03% of compound ST-3a-1 and 0.005% of compound H-1-1.

[0502] [ka]

[0503] <Mixture M8>

[0504] [Table 52]

[0505] <Mixture M9>

[0506] [Table 53]

[0507] <Mixture M10>

[0508] [Table 54]

[0509] <Mixture example P3> The example mixture P3 consists of 99.595% mixture M3, 0.40% compound RM-1 and 0.005% compound ST-3a-1.

[0510] <Mixture M11>

[0511] [Table 55]

[0512] <Mixture M12>

[0513] [Table 56]

[0514] <Mixture M13>

[0515] [Table 57]

[0516] <Mixture M14>

[0517] [Table 58]

[0518] <Mixture M15>

[0519] [Table 59]

[0520] <Mixture M16>

[0521]

Table 60

[0522] <Mixture M17>

[0523]

Table 61

[0524] <Mixture M18>

[0525]

Table 62

[0526] <Mixture M19>

[0527]

Table 63

[0528] <Mixture M20>

[0529]

Table 64

[0530] <Mixture M21>

[0531]

Table 65

[0532] <Mixture M22>

[0533]

Table 66

[0534] <Mixture M23>

[0535]

Table 67

[0536] <Mixture M24>

[0537]

Table 68

[0538] <Mixture M25>

[0539]

Table 69

[0540] <Mixture M26>

[0541]

Table 70

[0542] <Mixture M27>

[0543]

Table 71

[0544] <Mixture M28>

[0545]

Table 72

[0546] <Mixture M29>

[0547]

Table 73

[0548] <Mixture M30>

[0549]

Table 74

[0550] <Mixture M31>

[0551]

Table 75

[0552] <Mixture M32>

[0553]

Table 76

[0554] <Mixture M33>

[0555]

Table 77

[0556] <Mixture M34>

[0557]

Table 78

[0558] <Mixture M35>

[0559]

Table 79

[0560] <Mixture M36>

[0561]

Table 80

[0562] To improve reliability, the mixtures according to examples M11 to M36 may be additionally stabilized with one, two or three stabilizers selected from the group of compounds a) to h) described below, in each case the stabilizers being added in an amount of 0.01 to 0.04% based on the total mixture.

[0563] [ka]

[0564] [ka]

[0565] [ka]

[0566] [ka]

[0567] [ka]

[0568] [ka]

[0569] [ka]

[0570] [ka]

[0571] [ka]

[0572] <Example of polymerizable mixture>

[0573] <Mixture example P1> The example mixture P1 consists of 99.595% of the mixture M1, 0.40% of the compound RM-1 and 0.005% of the compound ST-3a-1.

[0574] [ka]

[0575] <Mixture example P2> The example mixture P2 consists of 99.595% mixture M2, 0.40% compound RM-1 and 0.005% compound ST-3a-1.

[0576] <Mixture example P3> The example mixture P3 consists of 99.595% mixture M3, 0.40% compound RM-1 and 0.005% compound ST-3a-1.

[0577] <Mixture example P4> The example mixture P4 consists of 99.595% mixture M4, 0.40% compound RM-1 and 0.005% compound ST-3a-1.

[0578] <Mixture example P5> The example mixture P5 consists of 99.595% mixture M5, 0.40% compound RM-1 and 0.005% compound ST-3a-1.

[0579] <Mixture example P6> The example mixture P6 consists of 99.595% of mixture M1, 0.40% of compound RM-19 and 0.005% of compound ST-3a-1.

[0580] [ka]

[0581] <Mixture example P7> The example mixture P7 consists of 99.595% mixture M2, 0.40% compound RM-19 and 0.005% compound ST-3b-1.

[0582] [ka]

[0583] <Mixture example P8> The example mixture P8 consists of 99.595% mixture M3, 0.40% compound RM-35 and 0.005% compound ST-3a-1.

[0584] [ka]

[0585] <Mixture example P9> The example mixture P9 consists of 99.595% mixture M4, 0.40% compound RM-156 and 0.005% compound ST-3a-1.

[0586] [ka]

[0587] <Mixture example P10> The example mixture P10 consists of 99.595% of mixture M5, 0.40% of compound RM-157 and 0.005% of compound ST-3b-1.

[0588] [ka]

Claims

1. Liquid-crystalline medium comprising a) one or more compounds of the formula I, b) one or more compounds selected from the group of the formulae IIA, IIB, IIC and IID and c) one or more compounds of the formula III. 【Chemical 1】 (In the formula, R １ represents n-butyl or n-pentyl. 【Chemistry 2】 (In the formula, R ２Ａ , R ２Ｂ , R ２Ｃ and R ２Ｄ each independently represent H, an alkyl group having 1 to 7 carbon atoms, or an alkenyl group having 2 to 7 carbon atoms, each of which is unsubstituted or at least monosubstituted with a halogen, provided that one or more CH ２ The groups are formed by -O-, -S-, etc. so that the O atoms are not directly linked to each other. 【Chemistry 3】 -C≡C-, -CF ２ O-, -OCF ２ may be replaced by —, —OC—O— or —O—CO—; L １ and L ２ are each independently F, Cl, CF ３ or CHF ２ represents Y is H, F, Cl, CF ３ , CHF ２ or CH ３ represents Z ２ , Z ２Ｂ and Z ２Ｄ are each independently a single bond, —CH ２ CH ２ -, -CF ２ O-, -OCF ２ -, -CH ２ O-, -OCH ２ represents -, -COO-, or -OCO-; p represents 0, 1 or 2; q represents 0 or 1, and v represents 1, 2, 3, 4, 5 or 6. 【Chemistry 4】 (In the formula, R ３１ and R ３２ each independently represent H, an alkyl or alkoxy group having 1 to 7 C atoms, provided that one or more CH ２ The group is formed so that the O atoms are not directly connected to each other. 【Chemistry 5】 -C≡C-, -CF ２ O-, -OCF ２ each independently being replaced by -, -CH=CH-, -O-, -CO-O- or -O-CO-, in which one or more H atoms may be replaced by halogen; A ３ are, in each occurrence independently of one another, a 1,4-phenylene group in which one or two CH groups may be replaced by N, or a 1,4-cyclohexenylene or 1,4-cyclohexylene group in which one or two non-adjacent CH groups may be replaced by N. ２ The group may be substituted by —O— or —S—, provided that the group may be mono- or polysubstituted by halogen atoms, Z ３ are each independently of each other in their occurrences, -CF ２ O-, -OCF ２ -, -CH ２ O-, -OCH ２ -, -CH ２ -, -CH ２ CH ２ represents -, -CH=CH-, -C≡C- or a single bond, L ３１ and L ３２ are each independently F, Cl, CF ３ or CHF ２ represents W represents O or S, and n represents 0, 1 or 2.

2. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of the formula IIB-2 【Chemistry 6】 (Wherein alkyl and alkyl ＊ each independently represents a linear alkyl group having 1 to 6 carbon atoms, and (O) represents an oxygen atom or a single bond.

3. The medium comprises one or more compounds of formula IIB-2, wherein alkyl represents methyl or propyl; ＊ 3. The liquid-crystalline medium according to claim 2, wherein denotes ethyl.

4. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of the formula IV-3 【Chemistry 7】 (wherein alkyl represents an alkyl group having 1 to 7 carbon atoms, and alkenyl represents 【Chemistry 8】 wherein m is 0, 1 or 2, and n is 0, 1 or 2.

5. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of the formula IV-1 in a total amount in the range from 1% to 30%. 【Chemistry 9】 (In the formula, alkyl and alkyl' are the same or different and represent alkyl having 1 to 7 C atoms; However, compounds of formula I are excluded.

6. 6. The liquid-crystalline medium according to claim 5, wherein alkyl in formula IV-1 is methyl and alkyl' is n-propyl.

7. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of the formula IVa 【Chemistry 10】 (In the formula, R ４１ and R ４２ each independently represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy group having up to 12 C atoms, and 【Chemistry 11】 Z ４ is a single bond, -CH ２ CH ２ -, -CH=CH-, -CF ２ O-, -OCF ２ -, -CH ２ O-, -OCH ２ -, -COO-, -OCO-, -C ２ F ４ -, -C ４ H ８ - or -CF=CF-.)

8. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of formula V 【Chemistry 12】 (In the formula, R ５１ , R ５２ represents alkyl having 1 to 7 C atoms, alkoxy having 1 to 7 C atoms or alkoxyalkyl, alkenyl or alkenyloxy having 2 to 7 C atoms, 【Chemistry 13】 represents Z ５１ , Z ５２ are each independently —CH ２ -CH ２ -, -CH ２ represents —O—, —CH═CH—, —C≡C—, —COO— or a single bond, and n is 1 or 2.

9. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of formula VI 【Chemistry 14】 (In the formula, R ６ and R ６２ is R as defined in claim 1 ２Ａ or R ６２ are F, Cl, and CF ３ or OCF ３ represents L ６１ , L ６２ , L ６３ , L ６４ , L ６５ and L ６６ independently represent H or F, with the proviso that L ６１ , L ６２ , L ６３ , L ６４ , L ６５ and L ６６ At least one of represents F.

10. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of the formulae P1 to P4 【Chemistry 15】 (R Ｐ represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms or an alkenyl group having 2 to 6 C atoms, X Ｐ is a linear alkyl having 1 to 6 carbon atoms, F, Cl, CF ３ , OCF ２ H, OCF ３ , OCHFCF ３ , OCF ２ CHFCF ３ or OCH=CF ２ represents L Ｐ１ , L Ｐ２ and L Ｐ３ each independently represents H or F.

11. 10. Liquid-crystalline medium according to claim 1, 8 or 9, wherein the medium comprises one or more compounds selected from the group of compounds of the following formulae: 【Chemistry 16】 【Chemistry 17】 【Chemistry 18】 where the parameters are as defined in claims 1, 8 and 9, and alkyl and alkyl ＊ each independently represent a linear alkyl group having 1 to 6 carbon atoms, Alkenyl and alkenyl ＊ each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, (O) alkyl ＊ Or (O)-alkyl is alkyl ＊ or O-alkyl ＊ represents m represents 0, 1, 2, 3, 4, 5 or 6; R is R in formula IIA ２Ａ It means R １１ and R １２ are each independently R in formula IIA ２Ａ has one of the meanings of L １ and L ２ each independently represents F or Cl, L ３ is H or CH ３ represents (O) represents O or a single bond; R ＩＩＩＡ is an alkyl or alkenyl group having up to 7 C atoms or a group Cy-C ｍ H ２ｍ＋１ represents m and n are the same or different and each represents 0, 1, 2, 3, 4, 5, or 6; Cy represents an alicyclic group having 3, 4 or 5 ring atoms, which may be substituted with alkyl or alkenyl, each having up to 3 C atoms, or halogen or CN.

12. 2. Liquid-crystalline medium according to claim 1, wherein the medium comprises one or more compounds of formula H 【Chemistry 19】 (In the formula, Ar represents an aromatic or heteroaromatic hydrocarbon group having 4 to 40 C atoms; Sp represents a spacer group; R Ｓ represents H, alkyl having 1 to 12 C atoms or alkenyl having 2 to 12 C atoms; Z Ｓ is -O-, -C(O)O-, -(CH ２ ) ｚ - or - (CH ２ ) ｚ O— or a single bond; HA is, 【Chemistry 20】 represents; R Ｈ H, O ・ , C.H. ３ , OH or OR Ｓ represents; R Ｓ１ , R Ｓ２ , R Ｓ３ and R Ｓ４ are the same or different and represent alkyl having 1 to 6 C atoms; G is H or R Ｓ or group Z Ｓ - represents HA; z is an integer from 1 to 6; and q is 3 or 4.

13. 2. The liquid crystal medium according to claim 1, wherein the medium comprises one or more additives selected from the group consisting of dyes, dopants and reactive mesogens.

14. 10. A liquid crystal display comprising a liquid crystal medium according to claim 1.

15. 15. The display of claim 14, wherein the display is a VA, IPS, FFS, PS-VA, PS-IPS or PS-FFS display.

16. 2. Use of a liquid-crystalline medium according to claim 1 in a VA, IPS, FFS, PS-VA, PS-IPS or PS-FFS display.

17. 10. Use of a liquid-crystalline medium according to claim 1 for energy-saving liquid-crystal displays.

18. 10. A method for preparing a liquid crystal medium according to claim 1, comprising the step of mixing one or more compounds of formulae I and III with one or more compounds selected from formulae IIA, IIB, IIC and IID, optionally with one or more polymerizable mesogens and optionally with further LC compounds and / or additives.

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