Liquid-crystal medium

Abstract

To provide a liquid-crystal medium.SOLUTION: The present invention relates to a liquid-crystal (LC) material as defined in claim 1, having negative dielectric anisotropy and to the use thereof for optical, electro-optical and electronic purposes, such as for example in LC displays, in particular energy saving displays based on the ECB, IPS or FFS effect.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] One of the currently used liquid crystal display (LCD) modes is the TN (“twisted nematic”) mode. However, TN LCDs have the disadvantage that the contrast strongly depends on the viewing angle.

[0003] In addition, so-called VA (“vertically aligned”) displays with a wider viewing angle are known. The LC cell of a VA display has an LC medium layer between two transparent electrodes, where the LC medium usually has negative dielectric anisotropy. In the switched-off state, the molecules of the LC layer are oriented perpendicular to the electrode surface (homeotropic) or have a tilted homeotropic orientation. When a voltage is applied to the two electrodes, reorientation of the LC molecules occurs parallel to the electrode surface.

[0004] Also known are so-called IPS (“in-plane switching”) displays having an LC layer between two substrates, where the two electrodes are arranged on only one of the two substrates and preferably have an intermeshed comb-shaped structure. When a voltage is applied to the electrodes, this generates an electric field having a significant component parallel to the LC layer between the electrodes. Thereby, reorientation of the LC molecules in the layer plane occurs.

[0005] Furthermore, so-called FFS (“fringe-field switching”) displays have been reported (see, in particular, S.H. Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, p. 1028 (Non-Patent Document 1)). This display has two electrodes on the same substrate, one of which is structured in a comb shape and the other is unstructured. As a result, a strong so-called “fringe field,” i.e., a strong electric field near the electrode ends, is generated, and an electric field having both a strong vertical component and a strong horizontal component is generated across the cell. The FFS display has a low viewing angle dependence of contrast. The FFS display usually contains an LC medium having a positive dielectric anisotropy and an alignment layer, usually a polyimide alignment layer, which provides a planar alignment to the molecules of the LC medium.

[0006] The FFS display can be operated as an active matrix display or a passive matrix display. In the case of an active matrix display, individual pixels are usually addressed by integrated non-linear active elements, such as transistors (e.g., thin-film transistors (“TFTs”)), while in the case of a passive matrix display, individual pixels are usually addressed by multiplexing methods known from the prior art.

[0007] An FFS display is disclosed that has an electrode design and layer thickness similar to an FFS display, but includes an LC medium layer having negative dielectric anisotropy instead of an LC medium layer having 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)). The LC medium having negative dielectric anisotropy exhibits a more preferable director orientation with a smaller tilt and a higher twist orientation compared to an LC medium having positive dielectric anisotropy. As a result, these displays have higher transmittance. This display further has 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 causes a planar alignment of the LC molecules of the LC medium. These displays are also known as "Ultra Brightness FFS (UB-FFS)" mode displays. These displays require an LC medium with high reliability. <> <>

[0008] <> In a more recent type of VA display, the uniform alignment of LC molecules is limited to a plurality of relatively small domains within the LC cell. There may be disclinations between these domains, which are also known as tilt domains. A VA display having tilt domains has a larger viewing angle independent of contrast and intermediate gradations compared to a conventional VA display. In addition, this type of display is easy to manufacture, and further processing of the electrode surface, such as rubbing, for uniformly aligning the molecules in the switched-on state is no longer necessary. Instead, the preferential direction of the tilt angle or pretilt angle is controlled by a special design of the electrodes. <> <>

[0009] <> In a so-called MVA ("multidomain vertical alignment") display, this is usually achieved by electrodes with protrusions, which causes local pretilt. As a result, when a voltage is applied, the LC molecules are oriented parallel to the electrode surface in various directions and in various defined regions of the cell. This achieves a "controlled" switch and prevents the formation of interfering disclination lines. Although this arrangement improves the viewing angle of the display, it results in a decrease in light transmittance. Further development of MVA uses protrusions only on one electrode side, while the opposite electrode has slits, thereby improving light transmittance. The electrode with slits generates a non-uniform electric field in the LC cell when a voltage is applied, which means that controlled switching is still achieved. The distance between the slits and the protrusions can be increased to further improve light transmittance, but this results in an increase in response time. In a so-called PVA ("patterned VA") display, the protrusions are completely redundant in that both electrodes are structured by slits on the opposite side, which results in an increase in contrast and an improvement in light transmittance, but is technically difficult and makes the display more sensitive to mechanical effects ("tapping", etc.). However, for many applications, such as monitors, especially TV screens, a reduction in response time and an improvement in the contrast and brightness (transmittance) of the display are required.

[0010] Further development is the so-called PS ("polymer sustained") or PSA ("polymer sustained alignment") type of display, for which the term "polymer stabilised" is also sometimes used. In these displays, a small amount (e.g., 0.3 wt%, typically less than 1 wt%) of one or more polymerizable compounds (one or more), preferably polymerizable monomer compounds (one or more), is added to the LC medium. After filling the LC medium into the display, it is polymerized or crosslinked in situ, usually by ultraviolet photopolymerization, optionally while applying a voltage to the electrodes of the display. This polymerization is carried out at a temperature at which the LC medium exhibits a liquid crystal phase, usually at room temperature. It has been demonstrated that adding a polymerizable mesogen or liquid crystal compound, also known as a reactive mesogen or "RM", to the LC mixture is particularly appropriate.

[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. The polymerization of RM is preferably carried out while applying a voltage in the case of PS-VA and PS-OCB displays, and in the case of PS-IPS displays, with or without applying a voltage, preferably without applying a charge. As demonstrable in a test cell, the PS(A) method results in a pretilt in the cell. In the case of a PS-VA display, the pretilt has a positive effect on the response time. For a PS-VA display, standard MVA or PVA pixels and electrode layouts can be used. However, in addition, it is also possible to match on the side of the electrode where only one is structured, without protrusions, which significantly simplifies the manufacturing and at the same time results in very good contrast and at the same time very good light transmittance.

[0012] PS-VA displays are described, for example, in European Patent Application Publication No. 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).

[0013] For monitors, especially for television applications, however, the response time of LC displays, as well as the optimization of contrast and brightness (and thus also transmissivity), continues to be required. Here, the PSA method can offer significant advantages. Especially in the case of PS-VA, PS-IPS, and PS-FFS displays, a reduction in response time that is correlated with the pretilt measurable in the test cell can be achieved without a significant adverse effect on other parameters.

[0014] Another problem observed in the prior art is that when using a conventional LC medium in an LC display including but not limited to PSA type displays, especially when the LC medium is filled into a display cell manufactured using the one drop filling (ODF) method, unevenness often occurs in the display. This phenomenon is also known as "ODF unevenness". Therefore, it is desirable to provide an LC medium that leads to a reduction in ODF unevenness.

[0015] Another problem observed in the prior art is that LC media for use in PSA displays, including but not limited to PSA-type displays, often exhibit high viscosities, and as a result, high switching times. To reduce the viscosity and switching time of the LC media, it has been suggested in the prior art to add LC compounds having alkenyl groups. However, it has been observed that LC media containing alkenyl compounds often exhibit a decrease in reliability and stability and, in particular, a decrease in VHR 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 decrease in VHR in the LC media, which is quite disadvantageous for use in PSA displays.

[0016] In addition, there is a great demand for PSA displays and for LC media and polymerizable compounds for use in such PSA displays that enable a large operating temperature range while at the same time having a high resistivity, a short response time even at low temperatures, and a low threshold voltage, a low pretilt angle, a large number of intermediate gradations, a high contrast and a wide viewing angle, a high reliability and a high value of VHR after UV exposure, and in the case of the polymerizable compounds, a low melting point and a high solubility in the LC host mixture. For PSA displays for mobile applications, it is particularly desirable to be able to utilize an LC media that exhibits a low threshold voltage and a high birefringence.

[0017] One of the trends in displays is to achieve the fastest possible response time to obtain the best video quality. In this regard, a medium with negative dielectric anisotropy is inherently disadvantaged compared to an LC medium with positive dielectric anisotropy. On the other hand, the use of a mixture with negative dielectric anisotropy enables high transmittance in a standard FFS cell layout, which has a positive impact on power consumption and the environment. In the art, it is necessary to achieve both fast response time and higher transmittance. Especially in the use in portable devices, there is a great demand for displays with high transmittance, which enables the use of a lower-intensity backlight, thus leading to a longer battery life and a more sustainable product. Alternatively, displays with improved contrast, especially under ambient light, and higher brightness can be realized. Also, due to the popularity of 8K and gaming monitors, there is an increasing demand for LC display panels with a higher refresh rate, and thus for LC media with a faster response time.

[0018] Another important trend in displays is to achieve a high contrast ratio. The contrast ratio is represented by the ratio of the bright state to the dark state of the display. Especially in LCDs with IPS / FFS technology, the dark state is strongly affected by the scattering parameter, which has a great impact on the contrast ratio. To improve the contrast ratio and reduce the scattering parameter, a liquid crystal mixture with a high elastic constant is required. However, current liquid crystal monomers and mixtures have limitations in achieving extremely high elastic constants. Therefore, the development of new materials is required to further increase the contrast ratio of future displays.

[0019] Therefore, there is still a great demand for an LC medium that may contain a polymerizable compound for use in VA, FFS, or PSA displays that do not show the above-mentioned drawbacks, or show only minor drawbacks and have improved properties, and for use in VA, FFS, or PSA displays.

Prior Art Documents

Patent Documents

[0020]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Non-Patent Document

[0021]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0022] The present invention is based on the object of providing a novel and suitable LC medium that does not have or has to a reduced extent the drawbacks shown above.

Means for Solving the Problems

[0023] Surprisingly, by using a liquid crystal medium containing a compound of formula I, it has been found that the disadvantages of the prior art materials are not shown, or at least shown to a significantly reduced extent, and a liquid crystal medium having an appropriately high negative Δε, an appropriate phase range and Δn, and a high LTS can be realized.

[0024] The present invention relates to a liquid crystal medium containing a compound of formula I.

[0025]

Chemical formula

Chemical formula

[0026] The medium preferably contains one or more compounds selected from the group of compounds of formulae IIA, IIB, IIC and IID.

Chemical formula

[0027] In the formula, R 2A 、R 2B 、R 2C and R 2D are the same or different and are H, a linear alkyl or alkoxy having 1 to 15 C atoms, a linear alkenyl or alkenyloxy having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy having 3 to 15 C atoms each, provided that one or more CH2 groups in these groups are, independently of one another, such that O atoms are not directly linked to one another,

Chemical formula

[0028] The present invention further relates to an LC display comprising an LC medium according to the invention, in particular a VA, IPS, FFS or UB-FFS or PSA display, particularly preferably an FFS, UB-FFS, VA or PS-VA display.

[0029] The present invention further relates to the use of the LC medium according to the invention in a PSA display, in particular, preferably for generating a tilt angle in the LC medium by in-situ polymerization of a polymerizable reactive mesogen (RM) in the PSA display in an electric or magnetic field, in a PSA display comprising an LC medium.

[0030] 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 formula I with one or more compounds of formulae IIA, IIB, IIC and / or IID, optionally with one or more chiral dopants, optionally with one or more polymerizable compounds, and optionally with further LC compounds and / or additives.

[0031] The present invention further relates to the use of the LC medium according to the invention in a polymer-stabilized SA-VA display and to a polymer-stabilized SA-VA display comprising the LC medium according to the invention.

[0032] The present invention further relates to a method for manufacturing an LC display as described above and below, comprising the step of filling or otherwise providing between the substrates of the display an LC medium which may comprise one or more polymerizable compounds as described above and below, and optionally the step of polymerizing the polymerizable compounds.

[0033] The LC medium according to the invention exhibits the following advantageous properties, particularly when used in an FFS display: · Excellent low-temperature stability (LTS), · Improved contrast ratio of the display, · High transparency of the display, · High clearing temperature, · High voltage holding ratio, · Low rotational viscosity, · Fast switching, · Fast response time enabling a low power consumption LCD to extend the battery life for portable devices, · When used especially outdoors, it has sufficient stability against heat and / or UV, · A high elastic constant.

Mode for Carrying Out the Invention

[0034] According to another aspect of the present invention, there is provided a compound of formula I as defined above, wherein the group L 11 and L 12 one of which represents H, and the groups L 11 and L 12 the other of which represents F, Cl, CF3 or CHF2.

[0035] According to another aspect of the present invention, there is provided a compound of formula (3) defined in Scheme 1 below.

[0036] The compounds of general formula I are prepared by methods known per se, exactly as described in the literature (for example, standard literature, such as Methoden der organischen Chemie [Methods of Organic Chemistry] by Houben-Weyl, Georg-Thieme-Verlag, Stuttgart), i.e., known and under reaction conditions suitable for said reactions. In this specification, variant methods which are known per se but not mentioned in more detail herein can also be used. If desired, the starting materials can also be generated in situ by not isolating them from the reaction mixture but instead reacting them directly further to give the compounds of general formula I.

[0037] The compounds of formula I can be synthesized in the same manner as the synthesis of structurally related chlorofluoro derivatives shown in European Patent Application Publication No. 1897928.

[0038] A preferred synthetic route for the compounds of formula I is shown in Scheme 1.

Chemical Formula

[0039] The compound of formula I is preferably selected from the compounds of formulas I-1 to I-3.

Chemical formula

[0040] In the formula, R 11 and R 12 have the meanings defined in formula I above, and preferably represent a linear alkyl having 1 to 7 C atoms or a linear alkenyl having 2 to 15 C atoms, and in the group, one or more CH2 groups are, independently of each other,

Chemical formula

[0041] More preferably, the medium according to the present invention contains one or more of the compounds of formula I-1, and very preferably is selected from the compounds of formulas I-1-1 to I-1-32.

Chemical formula

[0042]

Chemical formula

[0043]

Chemical formula

[0044]

Chemical formula

[0045] The compound of formula I-2 is preferably selected from the compounds of formulas I-2-1 to I-2-32.

[0046]

Chem.

[0047]

Chem.

[0048]

Chem.

[0049]

Chem.

[0050]

Chem.

[0051] The compound of formula I-3 is preferably selected from the compounds of formulas I-3-1 to I-3-32.

[0052]

Chem.

[0053]

Chem.

[0054]

Chem.

[0055]

Chem.

[0056]

Chem.

[0057] Preferred compounds of Formulas IIA, IIB, IIC and IID are shown below.

[0058]

Chem.

[0059]

Chem.

[0060]

Chem.

[0061]

Chem.

[0062]

Chem.

[0063]

Chem.

[0064]

Chem.

[0065]

Chem.

[0066]

Chem.

[0067]

Chem.

[0068]

Chem.

[0069]

Chem.

[0070]

Chem.

[0071]

Chem.

[0072] In the formula, parameter a represents 1 or 2, and alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 C atoms, alkenyl and alkenyl * represent a linear alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl and alkenyl * preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0073] Highly preferred compounds of formula IID are selected from the following sub-formulas.

[0074]

Chem.

[0075]

Chem.

[0076]

Chem.

[0077]

Chem.

[0078]

Chem.

[0079] In a preferred embodiment, the medium comprises one or more compounds of formula IID-10a.

[0080]

Chem.

[0081] wherein the groups and parameters that appear have the meanings given above under formula IID, and R 2 represents

Chem.

[0082] Preferred compounds of formula IID-10a are compounds IID-10a-1 to IID-10a-14.

[0083]

Chem.

[0084]

Chem.

[0085] [Chemistry]

[0086] Particularly preferred mixtures according to the invention comprise one or more compounds of formulae 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.

[0087] Particularly preferred media according to the invention comprise at least one compound of formula IIC-1.

[0088] [Chemistry]

[0089] wherein alkyl and alkyl * have the meanings given above.

[0090] In particular, the medium comprises one or more compounds of formula IIA-2 selected from the following sub-formulae.

[0091] [Chemistry]

[0092] Alternatively or 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.

[0093] [Chemistry]

[0094] In particular, the medium comprises one or more compounds of formula IIA-10 selected from the following sub-formulae.

[0095] [Chemistry]

[0096] Alternatively, 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.

[0097]

Chem.

[0098] In particular, the medium comprises one or more compounds of formula IIB-10 selected from the following sub-formulae.

[0099]

Chem.

[0100] Alternatively, 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.

[0101]

Chem.

[0102] Alternatively, preferably in addition to the compound of formula IIC-1, the medium comprises one or more compounds of formulae IIC-1a-1 and IIC-1a-2.

[0103]

Chem.

[0104] In the formula, alkyl represents a linear alkyl having 1 to 7 C atoms, preferably 2 to 5 C atoms, and very preferably represents ethyl.

[0105] The medium according to the invention preferably comprises one or more compounds of formula III.

[0106] [Chemical formula]

[0107] In the formula, R 31 and R 32 each independently represents H, an alkyl or alkoxy group having 1 to 15 carbon atoms, provided that one or more CH2 groups in these groups are arranged such that O atoms are not directly linked to each other, [Chemical formula] -CH=CH-, -C≡C-, -CF2O-, -OCF2-, -O-, -CO-O- or -O-CO-, and may each independently be replaced thereby, and one or more H atoms in the group may be replaced by halogen, A 3 each independently at each occurrence, a) a 1,4-cyclohexenylene or 1,4-cyclohexylene group (in which one or two non-adjacent CH2 groups may be replaced by -O- or -S-), b) a 1,4-phenylene group (in which one or two CH groups may be replaced by N), or c) a group from the group of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, provided that the groups a), b) and c) may be mono- or polysubstituted by halogen atoms, n represents 0, 1 or 2, preferably 0 or 1, Z 31represents, independently of each other at each occurrence, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CH2O-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, and L 31 and L 32 each independently represents F, Cl, CF3 or CHF2, preferably H or F, most preferably F, and W represents O or S.

[0108] The compound of formula III is preferably selected from the compounds of formula III-1 and / or III-2.

[0109]

Chemical formula

[0110] wherein the groups occurring have the same meaning as given above for formula III, preferably R 31 and R 32 each independently represents an alkyl, alkenyl or alkoxy group having up to 15 C atoms, more preferably one or both of them represent an alkoxy group, L 11 and L 12 each preferably represents F.

[0111] Preferably, the compound of formula III-1 is selected from the group of compounds of formula III-1-1 to III-1-11, preferably the compound of formula III-1-6.

[0112]

Chemical formula

[0113]

Chemical formula

[0114] wherein alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 carbon atoms, alkenyl and alkenyl * each independently represent a linear alkenyl group having 2 to 6 carbon atoms, alkoxy and alkoxy * each independently represent a linear alkoxyl group having 1 to 6 carbon atoms, L 31 and L 32 each independently represent F or Cl, preferably both F.

[0115] Preferably, the compound of formula III-2 is selected from the group consisting of compounds of formula III-2-1 to III-2-10, preferably the compound of formula III-2-6.

[0116]

Chemical formula

[0117]

Chemical formula

[0118] wherein alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 carbon atoms, alkenyl and alkenyl * each independently represent a linear alkenyl group having 2 to 6 carbon atoms, alkoxy and alkoxy * each independently represent a linear alkoxyl group having 1 to 6 carbon atoms, L 31 and L 32 each independently represent F or Cl, preferably both F.

[0119] The medium may contain one or more compounds of formula IIIA-1 and / or IIIA-2.

[0120]

Chemical formula

[0121] In the formula, L 31 and L 32 have the same meaning as given above in formula III, (O) represents O or a single bond, R IIIA represents an alkyl or alkenyl having up to 7 C atoms or the group Cy-C m H 2m+1 -, 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 an alicyclic group having 3, 4 or 5 ring atoms, which may be substituted with alkyl or alkenyl having up to 3 C atoms or halogen or CN, preferably represents cyclopropyl, cyclobutyl, cyclopentyl, cyclopent-1-enyl, cyclopent-2-enyl and cyclopent-3-enyl.

[0122] The compounds of formula IIIA-1 and / or IIIA-2 are either alternative or additional to the compounds of formula III and are preferably additionally included in the medium.

[0123] Very preferred compounds of formula IIIA-1 and IIIA-2 are the following.

[0124]

Chemical formula

[0125]

Chemical formula

[0126] In the formula, alkoxy represents a linear alkoxy group having 1 to 6 C atoms, or -(CH2) n F (where n is 2, 3, 4 or 5), preferably represents C2H4F.

[0127] In a preferred embodiment of the present invention, the medium contains one or more compounds of formula III-3.

[0128]

Chemical formula

[0129] In the formula 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 CH2 groups in these groups are such that O atoms are not directly connected to each other, -C≡C-, -CF2O-, -OCF2-, -CH=CH-,

Chemical formula

[0130] The compound of formula III-3 is preferably selected from the group of compounds of formula III-3-1 to III-3-10.

[0131]

Chemical formula

[0132]

Chemical formula

[0133] In the formula, R 32is 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 (where n is 2, 3, 4 or 5.), preferably represents C2H4F.

[0134] In a preferred embodiment of the present invention, the medium comprises one or more compounds of formulae III-4 to III-6, preferably of formula III-5.

[0135]

Chemical formula

[0136] wherein the parameters have the meanings given above, R 31 preferably represents a linear alkyl, R 32 preferably represents an alkoxy, each having 1 to 7 C atoms.

[0137] In a preferred embodiment, the medium 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.

[0138]

Chemical formula

[0139] wherein the parameters have the meanings given above, R 31 preferably represents a linear alkyl, R 32 preferably represents an alkoxy, each having 1 to 7 C atoms.

[0140] In a preferred embodiment, the medium comprises one or more compounds of formula IV.

[0141]

Chemical formula

[0142] In the formula, R 41 represents an alkyl group having 1 to 7 carbon atoms or an alkenyl group having 2 to 7 carbon atoms, preferably an n-alkyl group, particularly preferably having 2, 3, 4 or 5 carbon atoms, and R 42 represents an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 6 carbon atoms (both preferably having 2 to 5 carbon atoms), an alkenyl group having 2 to 7 carbon atoms, preferably having 2, 3 or 4 carbon atoms, more preferably a vinyl group or a 1-propenyl group, particularly a vinyl group.

[0143] The compound of formula IV is preferably selected from the group of compounds of formulae IV-1 to IV-4.

[0144]

Chemical formula

[0145] In the formula, alkyl and alkyl’ each independently represent an alkyl having 1 to 7 carbon atoms, preferably having 1 to 5 carbon atoms, alkenyl represents an alkenyl group having 2 to 5 carbon atoms, preferably having 2 to 4 carbon atoms, particularly preferably having 2 carbon atoms, alkenyl’ represents an alkenyl group having 2 to 5 carbon atoms, preferably having 2 to 4 carbon atoms, particularly preferably having 2 to 3 carbon atoms, alkoxy represents an alkoxy having 1 to 5 carbon atoms, preferably having 2 to 4 carbon atoms.

[0146] The compound of formula IV-1 is preferably selected from the group of compounds of formulae IV-1-1 to IV-1-6.

[0147]

Chemical formula

[0148] The compound of formula IV-2 is preferably selected from the compounds of formula IV-2-1 and IV-2-2.

[0149]

Chem.

[0150] The compound of formula IV-3 is preferably selected from the group consisting of the compounds of formula IV-3-1, IV-3-2 and IV-3-3.

[0151]

Chem.

[0152] Wherein alkyl has the meaning defined above, provided that the compound of formula I is excluded from formula IV-3-2.

[0153] The compounds of formula IV-3-1, IV-3-2 and IV-3-3 are preferably selected from the following compounds.

[0154]

Chem.

[0155] Very preferably, the medium according to the invention comprises a compound selected from the compounds of formula IV-4, in particular the compounds of formula IV-4-1 to IV-4-3.

[0156]

Chem.

[0157] The liquid crystal medium preferably additionally comprises one or more compounds of formula IVa.

[0158]

Chem.

[0159] In the formula, R 41 and R 42 each independently represent a linear alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy group having up to 12 carbon atoms, and

Chemical formula

[0160] Preferred compounds of formula IVa are shown below.

[0161]

Chemical formula

[0162] In the formula, alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 carbon atoms.

[0163] The medium according to the present invention preferably contains at least one compound of formula IVa-1 and / or formula IVa-2.

[0164] The proportion of the compound of formula IVa in the whole mixture is preferably less than 5% by weight, very preferably less than 2% by weight.

[0165] Preferably, the medium contains one or more compounds of formula IVb-1 to IVb-4, more preferably compounds of formula IVb-1 to IVb-3.

[0166]

Chemical formula

[0167] In the formula, alkyl and alkyl * each independently represents 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.

[0168] Among the compounds of Formulas IVb-1 to IVb-3, the compound of Formula IVb-2 is particularly preferred.

[0169] They are particularly preferred biphenyls.

[0170]

Chemical formula

[0171] In the formula, alkyl * represents an alkyl group having 1 to 6 C atoms, preferably n-propyl. The medium according to the present invention particularly preferably contains one or more compounds of Formulas IVb-1-1 and / or IVb-2-3.

[0172] In a particularly preferred embodiment, the medium according to the present invention contains one or more compounds of Formula V.

[0173]

Chemical formula

[0174] 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,

Chemical formula

[0175] The compound of formula V is preferably selected from the compounds of formula V-1, V-2 and V-3.

[0176]

Chemical formula

[0177] In the formula, the groups appearing have the meanings given above for formula V.

[0178] The compound of formula V-1 is preferably selected from the compounds of formula V-1-1 to V-1-8; The compound of formula V-2 is preferably selected from the compounds of formula V-2-1 to V-2-4; and The compound of formula V-3 is preferably selected from the compounds of formula V-3-1 to V-3-4.

[0179]

Chemical formula

[0180]

Chemical formula

[0181] In the formula, R 51 and R 52 have the meanings shown above for formula V. R 51 and R 52 preferably each independently represent a linear alkyl having 1 to 7 carbon atoms or an alkenyl having 2 to 7 carbon atoms.

[0182] A highly preferred compound of formula V-2-1 is selected from the compounds of formula V-2-1a to V-2-1g.

[0183] [ka]

[0184] Highly preferred compounds of formula V-2-2 are selected from the compounds of formulae V-2-2a to V-2-2i:

[0185] [ka]

[0186] A preferred medium according to the invention comprises one or more compounds of formula CL.

[0187] [ka]

[0188] During the ceremony R L represents H, a linear or branched alkyl or alkoxy group having 1 to 15 C atoms, or a linear or branched alkenyl group having 2 to 15 C atoms, provided that one or more CH groups in these groups are not directly linked to O atoms, [ka] -C≡C-, -CF2O-, -OCF2-, -CH=CH-, -O-, -CO-O- or -O-CO-, each of which may be replaced independently of the other, in which additionally one or more H atoms may be replaced by halogen; X L represents F, Cl, CN, CHF2, CF3, OCF3, or the same or different R L has one of the meanings of Y L represents H, F, Cl or CH3.

[0189] The compound of formula CL is preferably selected from the group of compounds of formula CL-1, CL-2 and CL-3.

[0190]

Chemical formula

[0191] In the formula, R L1 and R L2 are the same or different and have the meanings given above for formula I, preferably represent alkyl or alkenyl having 1 to 7 or 2 to 7 C atoms each, in which the CH2 groups may be replaced by cyclopropane-1,2-diyl, or R L2 represents an alkoxy having 1 to 5 C atoms.

[0192] Very preferably, the compound of formula CL is selected from the compounds of formula CL-3-1 to CL-3-12.

[0193]

Chemical formula

[0194]

Chemical formula

[0195] In a particularly preferred embodiment, the medium according to the invention comprises the compound CL-3-1 or CLP-3-3.

[0196] In a preferred embodiment of the invention, the medium additionally comprises one or more compounds of formula VI.

[0197]

Chemical formula

[0198] In the formula, R 61 and R 62represents a linear alkyl or alkoxy having H, F, 1 to 15 C atoms, a linear alkenyl or alkenyloxy having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy each having 3 to 15 C atoms, provided that in these groups one or more CH2 groups are such that O atoms are not directly linked to each other, and each independently of one another,

Chemical formula

[0199] The compound of formula VI is preferably selected from formula VI-1 and VI-2.

[0200]

Chemical formula

[0201] In the formula, the groups appearing have the meanings given for formula VI.

[0202] The compound of formula VI-1 is preferably selected from formulas VI-1-1 to VI-1-21, and very preferably from formula VI-1-4.

[0203]

Chem.

[0204]

Chem.

[0205]

Chem.

[0206] 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 preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0207] In the compound of formula VI-1-4, (O) preferably represents -O-.

[0208] The compound of formula VI-2 is preferably selected from formulas VI-2-1 to VI-1-15, and very preferably from formula VI-2-1.

[0209]

Chem.

[0210]

Chem.

[0211]

Chem.

[0212] 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 preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy.

[0213] In a preferred embodiment of the present invention, the medium additionally contains one or more compounds of formulas VII-1 to VII-9.

[0214]

Chemical formula

[0215]

Chemical formula

[0216] In the formula, 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 w is an integer from 1 to 6.

[0217] Preferably, the medium according to the present invention contains one or more compounds of formula VIII.

[0218]

Chemical formula

[0219] In the formula, R 81 and R 82is the same or different and represents H, halogen, CN, SCN, a linear alkyl or alkoxy having 1 to 15 C atoms, a linear alkenyl or alkenyloxy having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy having 3 to 15 C atoms, provided that one or more CH2 groups in these groups are arranged such that O atoms are not directly linked to each other,

Chemical formula

[0220] A in formula I 81 and A 81 are preferably phenylene-1,4-diyl (and this group may be mono- or polysubstituted with F), further cyclohexane-1,4-diyl, cyclohexenylene-1,4-diyl, tetrahydropyran-2,5-diyl or 1,3-dioxane-2,5-diyl, very preferably phenylene-1,4-diyl (and this group may be mono- or polysubstituted with F) or cyclohexane-1,4-diyl.

[0221] Z in formula VIII 81 and Z 81 are preferably -CF2O-, -OCF2- or a single bond, very preferably a single bond.

[0222] A in formula VIII 81 and A 81 are particularly preferably

Chemical formula

[0223] R 81 and R 82 each independently of one another represent H, F or alkyl, alkoxy, alkenyl or alkynyl having 1 to 8, preferably 1 to 5 C atoms, and each of these groups may be replaced by halogen, particularly preferably F, in the compound of formula VIII.

[0224] R 81 and R 82Preferably represents H, a fluorinated alkyl or alkoxy having 1 to 7 C atoms, a fluorinated alkenyl or alkynyl having 2 to 7 C atoms, or a fluorinated cycloalkyl having 3 to 12 C atoms.

[0225] Preferably R 81 and R 82 at least one of which is not H, particularly preferably R 81 and R 82 both are not H. R 81 is very particularly preferably alkyl. R 82 is more preferably H, alkyl or fluorine. Very particularly preferably R 81 is alkyl, and R 82 is H or alkyl. R 81 、R 82 each independently very particularly preferably represents an unbranched alkyl having 1 to 5 C atoms. R 81 and R 82 When representing a substituted alkyl, alkoxy, alkenyl or alkynyl, the total number of C atoms in the two groups R 81 and R 82 is preferably less than 10.

[0226] Preferred compounds of formula VIII are selected from compounds of formula VIIIa.

[0227]

Chemical formula

[0228] In the formula, R 1 and R 2 are the same or different and represent a linear alkyl having 1 to 15 C atoms, a linear alkenyl having 2 to 15 C atoms, or a branched alkyl or alkenyl having 3 to 15 C atoms, provided that one or more CH2 groups in these groups are

Chemical formula

[0229] Highly preferred compounds of formula VIIIa are selected from the compounds of formulae VIIIa-1 to VIIIa-35.

[0230]

Chemical formula

[0231]

Chemical formula

[0232]

Chemical formula

[0233]

Chemical formula

[0234]

Chemical formula

[0235]

Chemical formula

[0236] wherein v is an integer from 1 to 6.

[0237] Even more preferred compounds of formula VIII are selected from the following sub-formulae.

[0238]

Chemical formula

[0239] In the formula, R 81 , R 82 and L have the meanings shown above, L preferably represents F, and r, s and t are independently 0, 1, 2, 3 or 4. r is preferably 1 or 2, very preferably 2, and s and t are independently preferably 0 or 1, very preferably 0. R 81 and R 82 each independently represents n-alkyl having 1 to 5 C atoms in particular.

[0240] In the first very preferred embodiment, the compounds of formulas VIII-1 to VIII-6 are selected from the compounds of formulas VIII-1a to VIII-6a, in particular the compound of formula VIII-3a.

[0241]

Chemical formula

[0242] In the formula, R 81 , R 82 , r and s have the meanings defined above.

[0243] In the second very preferred embodiment, the compounds of formulas VIII-1 to VIII-6 are selected from the compounds of formulas VIII-1b to VIII-6b, in particular the compound of formula VIII-3-b.

[0244]

Chemical formula

[0245] In the formula, R 81 , R 82 , L, r and s have the meanings defined above.

[0246] In the third very preferred embodiment, the compounds of formulas VIII-1 to III-6 are selected from the compounds of formulas III-1c to III-6c, in particular the compound of formula III-3-c.

[0247] [Chemical formula]

[0248] In the formula, R 81 , R 82 , L, r and s have the meanings defined above.

[0249] In a fourth highly preferred embodiment, the compounds of formulas VIII-1 to VIII-6 are selected from the compounds of formulas VIII-1d to VIII-6d, particularly the compound of formula VIII-3d.

[0250] [Chemical formula]

[0251] In the formula, R 81 , R 82 , L, r and s have the meanings defined above.

[0252] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from the group of compounds of formulas VIII-1a to VIII-6a and one or more compounds selected from the group of compounds of formulas VIII-1b to VIII-6b.

[0253] Very particularly preferably, the medium comprises one or more compounds selected from the group of compounds of formulas VIII-3a, VIII-3b, VIII-3c and VIII-3d.

[0254] [Chemical formula]

[0255] In the formula, R 81 , R 82 , L and r have the meanings defined above, and preferably r is 0.

[0256] The most preferred compounds of formula I include, in particular, one or more of the following.

[0257] [Chemistry]

[0258] [Chemistry]

[0259] [Chemistry]

[0260] Alternatively or additionally, compounds of formula I below may be used.

[0261] [Chemistry]

[0262] [Chemistry]

[0263] [Chemistry]

[0264] [Chemistry]

[0265] In a preferred embodiment, the medium comprises one or more compounds of formula IX.

[0266] [Chemistry]

[0267] wherein, R 1 and R 2is the same as or different from H, halogen, a linear alkyl or alkoxy having 1 to 15 C atoms, a linear alkenyl or alkenyloxy having 2 to 15 C atoms or a branched alkyl, alkoxy, alkenyl or alkenyloxy having 3 to 15 C atoms, provided that one or more CH2 groups in these groups are arranged such that O atoms are not directly linked to each other,

Chemical formula

[0268] When n is 0 and Y represents H or CH3, more preferably H, and L 11 and L 12 represent F, an LC medium containing a compound of formula IX is preferred.

[0269] Highly preferred compounds of formula IX are selected from the compounds of formulae IX-1 to IX-35.

[0270]

Chemical formula

[0271]

Chemical formula

[0272]

Chem.

[0273]

Chem.

[0274]

Chem.

[0275]

Chem.

[0276] In a preferred embodiment of the present invention, the medium contains one or more compounds of formula X.

[0277]

Chem.

[0278] In the formula,

Chem.

Chem.

Chem.

[0279] In the compound of formula X, R X preferably represents alkyl having 1 to 6 C atoms or alkenyl having 2 to 6 C atoms, and the group is preferably linear.

[0280] In the compound of formula X, X X is preferably F, Cl, or a monofluorinated or polyfluorinated alkyl or alkoxy group having 1, 2 or 3 C atoms or a monofluorinated or polyfluorinated alkenyl group having 2 or 3 C atoms. X X is more preferably F, Cl, CF3, CHF2, OCF3, OCHF2, OCFHCF3, OCFHCHF2, OCFHCHF2, OCF2CH3, OCF2CHF2, OCF2CHF2, OCF2CF2CHF2, OCF2CF2CHF2, OCFHCF2CF3, OCFHCF2CHF2, OCF2CF2CF3, OCF2CF2CClF2, OCClFCF2CF3, OCH=CF2 or CH=CF2, very preferably F or OCF3, further CF3, OCF=CF2, OCHF2 or OCH=CF2, very particularly preferably F, OCF3 or CF3, and most preferably F.

[0281] Preferred compounds of formula X are selected from the following sub-formulas.

[0282]

Chem.

[0283] In the formula, R X has one of the meanings given by formula X, preferably a linear alkyl having 1 to 6 C atoms, very preferably ethyl, propyl or butyl, or a linear alkenyl having 2 to 6 C atoms, very preferably vinyl or 1-propenyl, most preferably vinyl, and X X has one of the meanings given by formula X, preferably represents F, CF3 or OCF3, very preferably F.

[0284] Very preferred compounds of formula X are selected from the following sub-formulas.

[0285]

Chem.

[0286]

Chem.

[0287]

Chem.

[0288]

Chem.

[0289]

Chem.

[0290] Preferably, the LC medium contains one or more compounds selected from the group consisting of formulas X1-1, X1-3, X2-1 and X2-3.

[0291] Even more preferred embodiments are listed below.

[0292] a liquid crystal medium containing at least one compound of formulae Z-1 to Z-8, preferably formulae Z-2, Z-4 and Z-6, very preferably Z-4.

[0293]

Chemical formula

[0294] In the formula, R Z has the meaning of R shown above, preferably represents alkyl having 1 to 7 carbon atoms or alkenyl having 2 to 7 carbon atoms, 2A (O) represents O or a single bond, and alkyl represents alkyl having 1 to 7 carbon atoms.

[0295] b) Preferred liquid crystal media according to the invention contain one or more substances containing tetrahydronaphthyl or naphthyl units, such as compounds of formulae N-1 to N-5.

[0296]

Chemical formula

[0297] In the formula, R 1N and R 2N each independently have the meaning shown for R 2A and preferably represent linear alkyl, linear alkoxy or linear alkenyl, Z 1 and Z 2 each independently represent -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond.

[0298] ​c) A preferred mixture contains one or more compounds selected from the group consisting of difluorodibenzochroman compounds of formula BC, chromans of formula CR, and fluorinated phenanthrenes of formula PH-1 and PH-2.

[0299]

Chemical formula

[0300] In the formula, R B1 、R B2 、R CR1 、R CR2 、R P1 、R P2 each independently has the meaning of R 31 in formula III, and c is 0, 1, or 2. R 1 and R 2 preferably each independently represent alkyl or alkoxy having 1 to 6 carbon atoms.

[0301] Particularly preferred compounds of formula BC, CR, and PH-1 are compounds BC-1 to BC-7, CR-1 to CR-5, and BP-1 to BP-7.

[0302]

Chemical formula

[0303]

Chemical formula

[0304]

Chemical formula

[0305] In the formula, alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 carbon atoms, alkenyl and alkenyl *represents a linear alkenyl group having 2 to 6 C atoms each independently of one another.

[0306] A mixture containing one, two or three compounds of formula BC-2, BC-3, BP-2 and / or BP-3, very preferably BP-2 and / or BP-3, especially BP-3, is more preferred.

[0307] d) Preferred mixtures contain one or more indane compounds of formula In.

[0308]

Chemical formula

[0309] In the formula, R 11 、R 12 and R 13 each represent a linear alkyl, alkoxy, alkoxyalkyl or alkenyl group having 1 to 6 C atoms each independently of one another, R 12 and R 13 alternatively represent halogen, preferably F,

Chemical formula

[0310] Preferred compounds of formula In are the compounds of formulae In-1 to In-16 shown below.

[0311]

Chemical formula

[0312]

Chemical formula

[0313]

Chemical formula

[0314] Compounds of formulas In-1, In-2, In-3 and In-4 are particularly preferred.

[0315] e) Preferred mixtures additionally contain one or more compounds of formulas L-1 to L-5.

[0316]

Chemical formula

[0317]

Chemical formula

[0318]

Chemical formula

[0319] wherein R, R 1 and R 2 each independently have the meaning given for R 2A in formula IIA above, and alkyl represents an alkyl group having 1 to 6 C atoms. The parameter s represents 1 or 2.

[0320] Compounds of formulas L1 to L9 are preferably used at a concentration of 5 to 15% by weight, particularly 5 to 12% by weight, very particularly preferably 8 to 10% by weight.

[0321] f) Preferred mixtures additionally contain one or more compounds of formula IIA-Y.

[0322]

Chemical formula

[0323] where R 11 and R 12 have one of the meanings given for R 2A in formula IIA above, and L1 and L 2 are the same or different and represent F or Cl.

[0324] Preferred compounds of formula IIA-Y are selected from the group consisting of the following sub-formulas.

[0325]

Chemical formula

[0326]

Chemical formula

[0327] wherein Alkyl and Alkyl * each independently represent 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 represent a linear alkenyl group having 2 to 6 C atoms, O represents an oxygen atom or a single bond. Alkenyl and Alkenyl * preferably represent CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0328] Particularly preferred compounds of formula IIA-Y are selected from the group consisting of the following sub-formulas.

[0329]

Chemical formula

[0330] wherein Alkoxy and Alkoxy * have the meanings defined above and preferably represent methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy.

[0331] Preferably, the medium according to the present invention contains a compound selected from the group of compounds of formula ST-1 to formula ST-18, very preferably a compound of formula ST-3.

[0332]

Chemical formula

[0333]

Chemical formula

[0334]

Chemical formula

[0335] [[ID=z8]]

Chemical formula

[0336] wherein R ST represents H, an alkyl or alkoxy group having 1 to 15 C atoms, provided that in addition, one or more CH2 groups in these groups are such that O atoms are not directly linked to each other, -C≡C-, -CF2O-, -OCF2-, -CH=CH-,

Chemical formula

Chemical formula

Chemical formula

[0337] Among the compounds of formula ST, the compounds of the following formula are particularly preferred.

[0338]

Chemical formula

[0339]

Chemical formula

[0340]

Chemical formula

[0341] In the compounds of formula ST-3a and ST-3b, n preferably represents 3. In the compounds of formula ST-2a, n preferably represents 7.

[0342] A very particularly preferred mixture according to the present invention comprises one or more stabilizers from the group of compounds of formula ST-2a-1, ST-3a-1, ST-3b-1, ST-8-1, ST-9-1, ST-12.

[0343]

Chemical formula

[0344]

Chem.

[0345] Preferably, the medium contains one or more compounds of formula S.

[0346]

Chem.

[0347] wherein, Ar represents a methylene group, an aromatic hydrocarbon group having 6 to 40 C atoms, or a heteroaromatic hydrocarbon group having 4 to 40 C atoms; preferably represents an aromatic hydrocarbon group having 6 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 represents -O-, -C(O)O-, -(CH2) z - or -(CH2) z O-, or a single bond; HA is

Chem.

[0348] In formula S, aryl represents an aromatic or heteroaromatic hydrocarbon group having 4 to 40 carbon atoms, and may contain one, two, three or four aromatic rings including a condensed ring which may be bonded directly or via an alkylene linking group having 1 to 12 carbon atoms. In the group, one or more H atoms may be replaced by alkyl or alkoxy having 1 to 6 carbon atoms or alkenyl having 2 to 6 carbon atoms, or by CN, CF3 or halogen. In the group, one or more CH2 groups may each independently be replaced by -O-, -S-, -NH-, -N(C1-C4-alkyl)-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CH=CH- or -C≡C- such that O or S atoms are not directly bonded to each other.

[0349] Preferred aryl groups are benzene, naphthalene, anthracene, biphenyl, m-terphenyl, p-terphenyl and (phenylalkyl)benzene, wherein the alkyl in the group is a straight-chain alkyl having 1 to 12 carbon atoms.

[0350] In a preferred embodiment, the medium according to the invention comprises a compound of formula S in which parameter q is 3 and G is group Z S -HA.

[0351] In another preferred embodiment, the medium according to the invention comprises a compound of formula S in which parameter q is 4 and G is H or R S as defined.

[0352] The compounds of formula S are preferably selected from the compounds of formulae S-1, S-2 and S-3.

[0353]

Chemical formula

[0354]

Chemical formula

[0355] During the ceremony, R H has the meaning given above and is preferably H or O · represents; Sp, which may be the same or different in each occurrence, represents a spacer group; W represents a linear or branched, optionally unsubstituted alkylene having 1 to 12 C atoms, in which one or more non-adjacent -CH2- groups may be replaced by -O-.

[0356] Preferred compounds of formula S-1 are selected from compounds of formula S-1-1:

[0357] [ka]

[0358] In the formula, R H has the meaning given above, preferably H or O · and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, and very preferably 7.

[0359] Preferred compounds of formula S-2 are selected from compounds of formula S-2-1:

[0360] [ka]

[0361] In the formula, R H has the meaning given above, preferably H or O · and n2 is the same or different in each occurrence, preferably the same and an integer from 0 to 12, preferably 2, 3, 4, 5 or 6, very preferably 3, and R S are identical or different at each occurrence, preferably identical and denote alkyl having 1 to 6 C atoms, preferably n-butyl.

[0362] The preferred compounds of formula S-3 are selected from the compounds of formula S-3-1.

[0363]

Chemical formula

[0364] In the formula, R H has the meaning given above, preferably H or O · represents, and n is an integer from 0 to 12, preferably 5, 6, 7, 8 or 9, very preferably 7.

[0365] The compounds of formulas S and ST-1 to ST-18 are preferably present in the liquid crystal mixture according to the invention in an amount of 0.005 to 0.5% each, based on the mixture.

[0366] When the mixture according to the invention contains two or more compounds from the group of compounds of formulas S and ST-1 to ST-18, the concentration increases correspondingly to 0.01 to 1% for two compounds, based on the mixture.

[0367] However, the total proportion of the compounds of formulas S and ST-1 to ST-18, based on the mixture according to the invention, is preferably not more than 2%.

[0368] The liquid crystal medium according to the invention, also referred to herein as a liquid crystal host mixture, is suitable for use in polymer-stabilized displays. For this purpose, the medium according to the invention may contain one or more polymerizable compounds of formula P.

[0369]

Chemical formula

[0370] In the formula, each independently of the others, each occurrence being the same or different, P represents a polymerizable group, Sp represents a spacer group or a single bond, A 1 、A2 is an aromatic, heteroaromatic, alicyclic or heterocyclic group, preferably having 4 to 25 ring atoms, which group may also include fused rings, which group is unsubstituted or mono- or polysubstituted with L, Z 1 is -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH2-CH2-CO-O-, -O-CO-CH2-CH2-, -CR 0 R 00 - or represents a single bond, R 0 、R 00 represents H or alkyl having 1 to 12 C atoms, R represents H, L or P-Sp-, L represents F, Cl, -CN, P-Sp- or linear, branched or cyclic alkyl having 1 to 25 C atoms, provided that one or more non-adjacent CH2 groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- so that O and / or S atoms are not directly connected to each other independently, provided that one or more H atoms may be replaced by P-Sp-, F or Cl, respectively, z is 0, 1, 2 or 3, and n1 is 1, 2, 3 or 4.

[0371] As used in this specification, the term "reliability" means the quality of the performance of a display that, over time, consists of different stress loads such as light load, temperature, humidity, voltage, etc., and display effects such as image sticking (area and line image sticking), unevenness, and contamination, which are known to those skilled in the art of liquid crystal displays. As a standard parameter for classifying reliability, the voltage holding ratio (VHR) value is usually used, which is a measure for maintaining a constant electric voltage in a test display. A high VHR is a prerequisite for high reliability of the LC medium.

[0372] Hereinafter, unless otherwise specified, the term "PSA" is used when referring to polymer-stabilized alignment type displays in general, and the term "PS" is used when referring to specific display modes such as PS-VA and PS-TN.

[0373] As used in this specification, the terms "active layer" and "switchable layer" mean layers in an electro-optical display, such as an LC display, that contain one or more types of molecules having structural and optical anisotropy, such as LC molecules, whose molecular orientation changes upon external stimuli such as an electric or magnetic field, and as a result, the transmittance of the layer to polarized or non-polarized light changes.

[0374] As used in this specification, the terms "tilt" and "tilt angle" are understood to mean an orientation in which the LC molecules of the LC medium are tilted with respect to the cell surface in an LC display (preferably a PSA display in this specification). In this specification, the 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 and parallel outer plates forming the LC cell. In this specification, a low value of the tilt angle (i.e., significantly deviating from the angle of 90°) corresponds to a large tilt. An appropriate method for measuring the tilt angle is given in the examples. Unless otherwise indicated, the tilt angle values disclosed above and below relate to this measurement method.

[0375] As used herein, the terms "reactive mesogen" and "RM (reactive mesogen)" are understood to mean a compound containing a mesogen or liquid crystal backbone and one or more functional groups suitable for polymerization linked to the backbone, and the functional groups are also referred to as "polymerizable groups" or "P".

[0376] Unless otherwise stated, as used herein, the term "polymerizable compound" is understood to mean a polymerizable monomer compound.

[0377] As used herein, the term "low molecular weight compound" is a term relative to "polymer compound" or "polymer", meaning a monomer and / or a compound not prepared by a polymerization reaction.

[0378] As used herein, the term "non-polymerizable compound" is understood to mean a compound that does not contain a functional group suitable for polymerization under the conditions normally applied for the polymerization of RM.

[0379] As used herein, the term "mesogen group" is known to those skilled in the art and described in the literature, and means a group that essentially contributes to the generation of a liquid-crystalline (LC) phase in low molecular weight or high molecular weight substances due to the anisotropy of its attractive and repulsive interactions. A compound containing a mesogen group (mesogen compound) does not necessarily have an LC phase by itself. Also, it is possible for the mesogen compound to exhibit LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogen groups are, for example, units having a rigid rod-like or disc-like shape. An overview of the terms and definitions used for 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, pp. 6340 - 6368.

[0380] As used herein, the terms "optically active" and "chiral" are synonyms for materials capable of inducing a helical pitch in a nematic host material, and are also referred to as "chiral dopants".

[0381] As used herein, the term "spacer group", also referred to as "Sp" above and below, is known to those skilled in the art and described in the literature, for example, see Pure Appl. Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340 - 6368. As used herein, the term "spacer group" or "spacer" means a flexible group, such as an alkylene group, that links a mesogenic group and one or more polymerizable groups in a polymerizable mesogenic compound.

[0382] Similarly, in the compounds of formula I, the spacer group is linked to a central hydrocarbon group having optical activity to stabilize the hindered amine functional group.

[0383] Above and below,

Chemical formula

[0384] Group

Chemical formula

[0385] Above and below, "organic group" represents a carbon or hydrocarbon group.

[0386] "Carbon-based" represents a monovalent or polyvalent organic group containing at least one carbon atom, provided that this does not contain additional types of atoms (e.g., -C≡C-), or may contain one or more additional atoms such as, for example, N, O, S, B, P, Si, Se, As, Te, or Ge (e.g., carbonyl, etc.). The term "hydrocarbon group" additionally contains one or more H atoms and represents a carbon group that may contain one or more heteroatoms such as, for example, N, O, S, B, P, Si, Se, As, Te, or Ge.

[0387] "Halogen" represents F, Cl, Br, or I, preferably F or Cl.

[0388] -CO-, -C(=O)-, and -C(O)- represent a carbonyl group, i.e.,

Chemical formula

[0389] The carbon or hydrocarbon group may be either a saturated or unsaturated group. The unsaturated group is, for example, an aryl, alkenyl, or alkynyl group. A carbon or hydrocarbon group having more than three C atoms may be linear, branched, and / or cyclic, and may also contain spiro linkages or fused rings.

[0390] Also, terms such as "alkyl", "aryl", "heteroaryl", etc. also include polyvalent groups, such as alkylene, arylene, heteroarylene, etc.

[0391] The term "aryl" represents an aromatic carbon group or a group derived therefrom. The term "heteroaryl" contains one or more heteroatoms (preferably selected from N, O, S, Se, Te, Si, and Ge) and represents "aryl" as defined above.

[0392] Preferred carbon and hydrocarbon groups may be substituted and have 1 to 40, preferably 1 to 20, particularly preferably 1 to 12 C atoms, and are linear, branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy, may be substituted and have 5 to 30, preferably 6 to 25 C atoms of aryl or aryloxy, or may be substituted and have 5 to 30, preferably 6 to 25 C atoms of alkylaryl, arylalkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy, provided that one or more C atoms may preferably be replaced by heteroatoms selected from N, O, S, Se, Te, Si and Ge.

[0393] Even 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 arylalkyl, C6-C 30 alkylaryloxy, C6-C 30 arylalkyloxy, C2-C 30 heteroaryl, C2-C 30 heteroaryloxy.

[0394] C1-C 12 alkyl, C2-C 12 alkenyl, C2-C 12 alkynyl, C6-C 25 aryl and C2-C 25 heteroaryl are particularly preferred.

[0395] More preferred carbon and hydrocarbon groups are alkyl groups which are linear, branched or cyclic and have 1 to 20, preferably 1 to 12 C atoms, and the group is unsubstituted or mono- or polysubstituted with F, Cl, Br, I or CN, provided that one or more non-adjacent CH2 groups are each independently of one another such that O and / or S atoms are not directly linked to one another, -C(R x )=C(R x )-, -C≡C-, -N(R x )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- may be replaced.

[0396] R x preferably represents H, F, Cl, CN, an alkyl chain which is linear, branched or cyclic and has 1 to 25 C atoms (provided that in addition, one or more non-adjacent C atoms may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, provided that one or more H atoms may also be replaced by F or Cl), or an aryl or aryloxy group which may be substituted and has 6 to 30 C atoms, or a heteroaryl or heteroaryloxy group which may be substituted and has 2 to 30 C atoms.

[0397] 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.

[0398] Preferred alkenyl groups include, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, and the like.

[0399] Preferred alkynyl groups include, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl, and the like.

[0400] Preferred alkoxy groups include, 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-decox, n-undecoxy, n-dodecox, and the like.

[0401] Preferred amino groups include, for example, dimethylamino, methylamino, methylphenylamino, phenylamino, and the like.

[0402] Aryl and heteroaryl groups may be monocyclic or polycyclic, i.e., they may contain one ring (e.g., phenyl, etc.) or two or more rings, and the group may be fused (e.g., naphthyl, etc.) or linked by a covalent bond (e.g., biphenyl, etc.), 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.

[0403] 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 are particularly preferred, and these groups may contain fused rings and may be substituted. Further, 5-membered, 6-membered, 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 so that O atoms and / or S atoms are not directly linked to each other.

[0404] Preferred aryl groups include, 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.

[0405] Preferred heteroaryl groups include, for example, 5-membered rings such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole; 6-membered rings such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine; or fused groups such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthimidazole, phenanthroimidazole, pyridimidazole, 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, benzoisoquinoline, acridine, phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarbazole, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiadiazothiophene; or combinations of these groups.

[0406] Also, the aryl and heteroaryl groups described above and below may be substituted with alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or further aryl or heteroaryl groups.

[0407] (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 that may also contain multiple bonds. Heterocyclic rings preferably contain one or more heteroatoms selected from Si, O, N, S, and Se.

[0408] (Non-aromatic) alicyclic and heterocyclic groups may be monocyclic, i.e., contain only one ring (e.g., cyclohexane, etc.), or polycyclic, i.e., contain multiple rings (e.g., decahydronaphthalene or bicyclooctane, etc.). Saturated groups are particularly preferred. Further, groups that are monocyclic, bicyclic, or tricyclic and have 5 to 25 ring atoms are preferred, and the group may contain a fused ring and may be substituted. Further, 5-membered, 6-membered, 7-membered, 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-.

[0409] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups such as cyclopentane, tetrahydrofuran, tetrahydrothiophene, pyrrolidine, etc., 6-membered groups such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane, 1,3-dithiane, piperidine, etc., 7-membered groups such as cycloheptane, etc., 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-methanoindane-xylylene-2,5-diyl, etc.

[0410] Preferred substituents are, for example, solubilizing groups such as alkyl or alkoxy, electron-withdrawing groups such as fluorine, nitro or nitrile, or substituents for raising the glass transition temperature (Tg) in the polymer, in particular, bulky groups such as, for example, t-butyl or an optionally substituted aryl group.

[0411] Preferred substituents will hereinafter also be referred to as "L" S ", and are, for example, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 , -C(=O)R x , -N(R x )2, a linear or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 25 C atoms (provided that one or more H atoms may be replaced by F or Cl), a silyl optionally having 1 to 20 Si atoms, or an aryl optionally having 6 to 25, preferably 6 to 15 C atoms.

[0412] In the formula, R x represents H, F, Cl, CN, a linear, branched or cyclic alkyl chain having 1 to 25 C atoms, provided that one or more non-adjacent CH2 groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- so that O- and / S- atoms are not directly linked to each other, provided that one or more H atoms may each be replaced by F, Cl, P- or P-Sp-, and Y 1 represents halogen.

[0413] "Substituted silyl or aryl" is preferably halogen, -CN, R 0 , -OR 0 , -CO-R 0 , -CO-O-R 0 , -O-CO-R 0 or -O-CO-O-R 0means substitution by, provided that R 0 represents H or an alkyl having 1 to 20 C atoms.

[0414] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and further, phenyl.

[0415] A 1 and A 2 are very preferably [Chemical formula] represents, wherein L has one of the meanings shown above, r represents 0, 1, 2, 3 or 4, particularly [Chemical formula] represents.

[0416] The polymerizable group P is, for example, a group suitable for a polymerization reaction such as free radical or ionic chain polymerization, polyaddition or polycondensation, or a group suitable for a polymer-analogous reaction such as addition or condensation onto the polymer main chain. Groups for chain polymerization, particularly those containing a C=C double bond or a C≡C triple bond, and groups suitable for ring-opening polymerization such as, for example, an oxetane or epoxide group are particularly preferred.

[0417] Preferred groups P are CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, [Chemical formula] CH2=CW 2 -(O) k3 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH2=CW 1-CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -, HS-CW 2 W 3 -, HW 2 N-, HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 selected from the group consisting of Si-, wherein W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, and W 2 and W 3 each independently of one another represent H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, and W 4 , W 5 and W 6 each independently of one another represent Cl, oxaalkyl or oxocarbonylalkyl having 1 to 5 C atoms, and W 7 and W 8 each independently of one another represent H, Cl or alkyl having 1 to 5 C atoms, Phe represents 1,4-phenylene which may be substituted by one or more groups L as defined above other than P-Sp-, k1, k2 and k3 each independently of one another represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0418] A very preferred group P is CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, [Chemical] CH2=CW 2 -O-, CH2=CW 2 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH- and W 4 W 5 W 6 selected from the group consisting of Si-, wherein W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular, H, F, Cl or CH3, and W 2 and W 3 each independently represent H or alkyl having 1 to 5 C atoms, in particular, H, methyl, ethyl or n-propyl, and W 4 W 5 and W 6 each independently represent Cl, oxaalkyl or oxocarbonylalkyl having 1 to 5 C atoms, and W 7 and W 8 each independently represent H, Cl or alkyl having 1 to 5 C atoms, Phe represents 1,4-phenylene, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0419] A very particularly preferred group P is CH2=CW 1-CO-O-, especially, CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, further, CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-, [Chemical formula] is selected from the group consisting of.

[0420] A more preferred polymerizable group P is selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide groups, and most preferably is selected from acrylate and methacrylate.

[0421] When the spacer group Sp is different from a single bond, Sp is preferably of the formula Sp”-X” such that each group P-Sp- corresponds to the formula R-Sp”-X”-, where Sp” and X” have the following meanings.

[0422] Sp” represents a linear or branched alkylene having 1 to 20, preferably 1 to 12 C atoms, which group may be mono- or polysubstituted by F, Cl, Br, I or CN, provided that in addition, one or more non-adjacent CH2 groups are each independently of one another replaced by -O-, -S-, -NH-, -N(R 0 )-, -Si(R 0 R 00 )-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N(R 00 )-CO-O-, -O-CO-N(R 0 )-, -N(R 0 )-CO-N(R 00 )-, -CH=CH- or -C≡C- may be replaced, X” is -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 )-, -N(R 0 )-CO-, -N(R 0)-CO-N(R 00 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -, -CY 2 =CY 3 -, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond, R 0 and R 00 each independently represent H or alkyl having 1 to 20 C atoms, Y 2 and Y 3 each independently represent H, F, Cl or CN.

[0423] X” is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 00 - or a single bond.

[0424] Typical spacer groups Sp and -Sp”-X”- are, for example, -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, -(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 0 R 00 -O) p1 -, where p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 0 and R 00 have the meanings given above.

[0425] Particularly preferred spacer groups Sp and -Sp”-X”- are -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, provided that p1 and q1 have the meanings given above.

[0426] Particularly preferred groups Sp” are each linear and are ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methylenoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.

[0427] In a preferred embodiment of the present invention, the compounds of formula P and its sub-formulas contain a spacer group Sp (branched polymerizable group) substituted with one or more polymerizable groups P such that the group Sp-P is Sp(P) s (where s is 2 or more).

[0428] Preferred compounds of formula P according to this preferred embodiment are those in which s is 2, i.e., compounds containing the group Sp(P)2. Very preferred compounds of formula P according to this preferred embodiment contain a group selected from the following formulas.

[0429]

Chemical formula

[0430] In the formula, P is as defined by formula P, Alkyl represents a single bond or a straight-chain or branched alkylene having 1 to 12 carbon atoms, and the group is unsubstituted or mono- or polysubstituted with F, Cl or CN, provided that one or more non-adjacent CH2 groups are each independently of one another such that O and / or S atoms are not directly linked to one another, -C(R 0 )=C(R 0 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- may be replaced, provided that R 0 has the meaning given above, aa and bb each independently of one another represent 0, 1, 2, 3, 4, 5 or 6, X has one of the meanings indicated for X", and preferably is O, CO, SO2, O-CO-, CO-O or a single bond.

[0431] Preferred spacer group Sp(P)2 is selected from formulae S1, S2 and S3.

[0432] Very preferred spacer group Sp(P)2 is selected from the following sub-formulae.

Chemical formula

[0433] In the compounds of formula P and its sub-formulae as above and below, P is preferably selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably acrylate and methacrylate.

[0434] All polymerizable groups P present in the compound have the same meaning, and the compounds of formula P and its sub-formulae as above and below, which very preferably represent acrylate or methacrylate, most preferably methacrylate, are even more preferred.

[0435] In the compounds of formula P and its sub-formulas as described above and below, R preferably represents P-Sp.

[0436] Sp is a single bond or -(CH2) p1 -, -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 where p1 is 2, 3, 4, 5 or 6, and when Sp is -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 the compounds of formula P and its sub-formulas as described above and below, in which the O atom or CO group is respectively linked to the benzene ring, are more preferred.

[0437] The compounds of formula P and its sub-formulas as described above and below, in which at least one group Sp is a single bond, are more preferred.

[0438] At least one group Sp is different from a single bond, preferably -(CH2) p1 -, -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 selected from, where p1 is 2, 3, 4, 5 or 6, and when Sp is -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 the compounds of formula P and its sub-formulas as described above and below, in which the O atom or CO group is respectively linked to the benzene ring, are more preferred.

[0439] The very preferred group -A 1 -(Z-A 2 ) z - in formula P is selected from the following formulas.

[0440]

Chemical formula

[0441] In the formula, at least one benzene ring is substituted with at least one group L, and the benzene ring may be further substituted with one or more groups L or P-Sp-.

[0442] Preferred compounds of formula P and their sub-formulas are selected from the following preferred embodiments (including any combination thereof): · All groups P in the compound have the same meaning. · -A 1 -(Z-A 2 ) z - is selected from A1, A2 and A5. · The compound has exactly two polymerizable groups (represented by group P). · The compound has exactly three polymerizable groups (represented by group P). · P is selected from the group consisting of acrylate, methacrylate, and oxetane, and very preferably acrylate or methacrylate. · P is methacrylate. · All groups Sp are single bonds. · At least one of the groups Sp is a single bond, and at least one of the groups Sp is different from a single bond. · When Sp is different from a single bond, -(CH2) p2 -, -(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or CO group is each linked to the benzene ring. · Sp is a single bond or -(CH2) p2 -, -(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, where p2 is 2, 3, 4, 5 or 6, and the O atom or CO group is each linked to the benzene ring. · R represents P-Sp-. · R does not represent or does not contain a polymerizable group. ·R does not represent or contain a polymerizable group and represents an alkyl having 1 to 25 C atoms in a linear, branched or cyclic form, provided that one or more non-adjacent CH2 groups are each replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- so that O and / or S atoms are not directly linked to each other, and provided that one or more H atoms are each replaced by F, Cl or L a and may be replaced by L ·L or L’ represents F, Cl or CN ·L is F

[0443] Suitable and preferred compounds of formula P are selected from the following formulas

[0444]

Chemical formula

[0445]

Chemical formula

[0446]

Chemical formula

[0447]

Chemical formula

[0448]

Chemical formula

[0449]

Chemical formula

[0450] In the formula, each group has the following meanings: P 1 、P 2 、P3 each independently represents an acrylate or methacrylate group, Sp 1 Sp 2 Sp 3 each independently represents a single bond or a spacer group having one of the meanings shown for Sp above and below, particularly preferably -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO- or -(CH2) p1 -O-CO-O-, where p1 is an integer from 1 to 12, provided that any additional group P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - at least one of which is different from R aa subject to the condition that one or more groups P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - may represent R aa and R aa is H, F, Cl, CN or a linear or branched alkyl having 1 to 25 C atoms (provided that one or more non-adjacent CH2 groups are each independently -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- so that O and / or S atoms are not directly linked to each other, provided that one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1- may be replaced by), particularly preferably an alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyl or alkylcarbonyloxy having 1 to 12 C atoms which may be linear or branched and may be mono-fluorinated or poly-fluorinated (however, the alkenyl and alkynyl groups have at least 2 C atoms and the branched groups have at least 3 C atoms). R 0 、R 00 each independently of one another, in each occurrence, represents H or an alkyl having 1 to 12 C atoms, which may be the same or different. R y and R z each independently of one another represents H, F, CH3 or CF3. X 1 、X 2 and X 3 each independently of one another represents -CO-O-, -O-CO- or a single bond. Z 1 represents -O-, -CO-, -C(R y R z )- or -CF2CF2-. Z 2 and Z 3 each independently of one another represents -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n -, where n is 2, 3 or 4. L, in each occurrence, may be the same or different and represents F, Cl, CN or an alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms which may be linear or branched and may be mono-fluorinated or poly-fluorinated, preferably F. L’ and L” each independently of one another represent H, F or Cl. k represents 0 or 1. r represents 0, 1, 2, 3 or 4. s represents 0, 1, 2 or 3. t represents 0, 1 or 2, and x represents 0 or 1.

[0451] Compounds of formulas P2, P13, P17, P22, P23, P24, P30, P31 and P32 are particularly preferred.

[0452] Trifunctional compounds selected from formulas P15 - P30, particularly formulas P17, P18, P19, P22, P23, P24, P25, P26, P30, P31 and P32 are even more preferred.

[0453] In the compounds of formulas P1 - P32, [Chemical formula]

[0454] wherein L has, in each occurrence, the same or different meaning and has one of the meanings shown above and below, preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, OCH3, COCH3 or OCF 3、 Particularly F or CH3.

[0455] Highly particularly preferred compounds of formula P are selected from Table E below.

[0456] To manufacture a PSA display, while optionally applying a voltage to the electrodes, in the LC medium between the substrates of an LC display, the polymerizable compound contained in the LC medium is polymerized or crosslinked (when one compound contains two or more polymerizable groups) by in-situ polymerization.

[0457] The structure of the PSA display according to the present invention corresponds to the normal configuration of the PSA display as described in the prior art cited at the beginning. A configuration without protrusions is preferred. In particular, in addition, it is preferred that the electrodes on the color filter side are not structured and only the electrodes on the TFT side have slits. An electrode structure particularly suitable and preferred for a PS-VA display is described, for example, in U.S. Patent Application Publication No. 2006 / 0066793.

[0458] A preferred PSA type LC display of the present invention comprises · a pixel electrode defining a pixel region, the pixel electrode being connected to a switching element disposed in each pixel region and optionally having a microslit pattern, and a first substrate including a first alignment layer optionally disposed on the pixel electrode; · a second substrate including a common electrode layer optionally disposed on the entire portion of the second substrate facing the first substrate, and an optional second alignment layer; · an LC layer including an LC medium layer disposed between the first substrate and the second substrate, the LC medium layer including a polymerizable component including one or more compounds of formula R and a liquid crystal host including those described above and below (however, the polymerizable component may be polymerized). and comprises.

[0459] The first and / or second alignment layer controls the alignment direction of the LC molecules of the LC layer. For example, in a PS-VA display, the alignment layer is selected such that the alignment layer makes the LC molecules in a homeotropic (or perpendicular) alignment (i.e., perpendicular to the surface) or a tilted alignment. Such an alignment layer includes, for example, polyimide, and the polyimide may be rubbed or prepared by an optical alignment method.

[0460] The LC layer having the LC medium can be disposed between the substrates of the display by a method commonly used in the manufacture of displays, for example, the so-called one-drop-filling (ODF) method. Then, the polymerizable component of the LC medium is polymerized, for example, by UV photopolymerization. The polymerization can be carried out in one step or two or more steps.

[0461] The PSA display may include further elements such as color filters, black matrices, passivation layers, optical retardation layers, transistor elements for addressing individual pixels, etc., all of which are known to those skilled in the art and can be used without exercising patentable skills.

[0462] The electrode structure can be designed by those skilled in the art according to the type of each display. For example, for a PS-VA display, by providing electrodes having slits and / or ridges or protrusions to generate two, four or more different tilt orientation directions, the multi-domain orientation of LC molecules can be induced.

[0463] Upon polymerization, the polymerizable compound forms a crosslinked polymer, and a certain pretilt of LC molecules occurs in the LC medium. Although not wishing to be bound by a particular theory, it is considered that at least a part of the crosslinked polymer formed by the polymerizable compound phase-separates or precipitates from the LC medium and forms a polymer layer on the substrate or the electrode or the alignment layer provided thereon. Microscopic measurement data (such as SEM and AFM) confirmed that at least a part of the formed polymer accumulates at the LC / substrate interface.

[0464] The polymerization can be carried out in a single step. Also, first, polymerization can be carried out while optionally applying a voltage in a first step to generate a pretilt angle, and subsequently, in a second polymerization step, without applying a voltage, polymerize or crosslink the compounds that did not react in the first step ("final curing").

[0465] Suitable and preferred polymerization methods can be achieved, for example, by thermal or photopolymerization, preferably by photopolymerization, particularly by UV-induced photopolymerization, by exposing the polymerizable compound to UV irradiation.

[0466] One or more types of polymerization initiators can be added to the LC medium. Appropriate conditions for polymerization and the appropriate type and amount of initiator are known to those skilled in the art and are described in the literature. For example, commercially available photoinitiators such as Irgacure651®, Irgacure184®, Irgacure907®, Irgacure369® or Darocure1173® (Ciba) are suitable for free radical polymerization. When using a polymerization initiator, the proportion of the initiator is preferably 0.001 to 5% by weight, particularly preferably 0.001 to 1% by weight.

[0467] Also, the polymerizable compound according to the present invention is also suitable for polymerization without an initiator, which has notable advantages such as, for example, lower material costs and, in particular, less contamination of the LC medium by the amount of the initiator or its degradation products that can remain. Thus, polymerization can also be carried out without adding an initiator. Therefore, in a preferred embodiment, the LC medium does not contain a polymerization initiator.

[0468] Also, for example, in order to prevent undesirable spontaneous polymerization of the RM during storage or transportation, the LC medium may contain one or more stabilizers. Appropriate types and amounts of stabilizers are known to those skilled in the art and are described in the literature. For example, stabilizers commercially available from the Irganox® series (Ciba), such as Irganox® 1076, are particularly suitable. When using a stabilizer, the proportion of the stabilizer is preferably 10 to 500,000 ppm, particularly preferably 50 to 50,000 ppm, based on the total amount of the RM or the polymerizable component (component P).

[0469] The polymerizable compound of formula P exhibits particularly good UV absorbency in a method comprising one or more of the following features for preparing a PSA display and is thus particularly suitable for that method: · Exposing the polymerizable medium to UV light in the display in a two-step process comprising a first UV exposure step (the "UV-1 step") for generating a tilt angle and a second UV exposure step (the "UV-2 step") for completing the polymerization; · Expose the polymeric medium to UV light generated by an energy-saving UV lamp (also known as a "green UV lamp") within the display. These lamps are characterized by a relatively low intensity (1 / 100 to 1 / 10 of that of conventional UV lamps) in the absorption spectrum of 300 - 380 nm, and are preferably used in the UV2 process, but can also be used in the UV1 process if it is necessary to avoid high intensity; · To avoid exposing the polymeric medium to short-wavelength UV light in the PS-VA process, expose the polymeric medium to UV light generated by a UV lamp having an emission spectrum shifted to a longer wavelength (preferably 340 nm or more) within the display.

[0470] Protect the organic layer from damage that can be caused by UV light, either by using a lower intensity or shifting to a longer wavelength of UV.

[0471] Preferred embodiments of the present invention relate to a method of preparing a PSA display described above and below, and include one or more of the following features: · Expose the polymeric LC medium to UV light in two stages, including a first UV exposure step ("UV-1 step") for generating a tilt angle and a second UV exposure step ("UV-2 step") for completing polymerization; · Expose the polymeric LC medium to UV light generated by a UV lamp having an intensity in the wavelength range of 300 - 380 nm of 0.5 mW / cm 2 ~10 mW / cm 2 (preferably, use this UV lamp in the UV2 process and optionally also in the UV1 process); · Expose the polymeric LC medium to UV light having a wavelength of 340 nm or more, preferably 400 nm or less.

[0472] This preferred method can be implemented, for example, by using a desired UV lamp or by using a band-pass filter and / or a cut-off filter that substantially transmits UV light having a respective desired wavelength and substantially blocks light having a respective undesired wavelength. For example, when irradiation with UV light having a wavelength λ in the range of 300 to 400 nm is desired, UV exposure can be carried out using a wide-band pass filter that substantially transmits wavelengths where λ is greater than 300 nm and less than 400 nm. When it is desired to irradiate with UV light having a wavelength λ greater than 340 nm, UV exposure can be carried out using a cut-off filter that substantially transmits wavelengths where λ is greater than 340 nm.

[0473] "Substantially transmits" means that the filter transmits most, preferably at least 50% of the intensity of the incident light of the desired wavelength. "Substantially blocks" means that the filter does not transmit most, preferably at least 50% of the intensity of the incident light of the undesired wavelength. "Desired (undesired) wavelength" means, for example, in the case of a band-pass filter, wavelengths within (outside) the given range of λ, and in the case of a cut-off filter, wavelengths above (below) the given value of λ.

[0474] This preferred method enables the manufacture of displays using longer wavelength UV, thereby reducing or avoiding the harmful and damaging effects of the short wavelength components of UV light.

[0475] The UV irradiation energy is generally 6 to 100 J, depending on the conditions of the manufacturing process.

[0476] Preferably, the LC medium according to the present invention consists essentially of a polymerizable component (P) containing a polymerizable compound of formula R as described above and below, or one or more polymerizable compounds of formula P, an LC host mixture, and an optically active component containing one or more chiral dopants. However, the LC medium preferably further contains one or more additional components or additives selected without limitation from the list including comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, hydrophobizing agents, adhesives, fluidity improvers, defoamers, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0477] Particularly preferred are LC media containing one, two or three polymerizable compounds of formula P.

[0478] Preferably, the proportion of the compound of formula P in the LC medium is more than 0% and less than 5%, very preferably more than 0% and less than 1%, and most preferably 0.01 to 0.5%.

[0479] In a preferred embodiment, the medium according to the present invention contains one or more compounds of formula S, preferably at a total concentration in the range of 10 ppm to 2000 ppm, more preferably 100 ppm to 1000 ppm, even more preferably 150 ppm to 500 ppm, very preferably 200 ppm to 400 ppm, particularly 250 to 300 ppm.

[0480] In another preferred embodiment, the medium according to the present invention contains one or more compounds of formula S, preferably at a total concentration in the range of 1000 ppm to 5000 ppm, more preferably more than 1000 ppm and less than 5000 ppm, even more preferably 1200 ppm to 4500 ppm, very preferably 2000 ppm to 4000 ppm, particularly 2500 to 3500 ppm.

[0481] The medium according to the present invention preferably has a negative dielectric anisotropy.

[0482] The liquid crystal mixture according to the invention is preferably nematic at a temperature of -20 °C or lower, preferably -30 °C or lower, very preferably -40 °C or lower.

[0483] The liquid crystal medium according to the invention advantageously has a nematic phase in the range of preferably -20 °C or lower to 90 °C or higher, particularly preferably -30 °C or lower to 100 °C or higher, very particularly preferably -40 °C or lower to 108 °C or higher.

[0484] In this specification, the expression "having a nematic phase" means that on the one hand no smectic phase and crystallization are observed at a lower temperature corresponding to the temperature in question, and on the other hand no transparency (transition to the isotropic phase) occurs during heating of the nematic phase at a given temperature. The examination at low temperatures is carried out using a flow viscosimeter at the corresponding temperature and is confirmed by storing in a test cell having a layer thickness corresponding to electro-optical applications for at least 100 hours. If the storage stability in the test cell at a temperature of -20 °C is 1000 hours or more, the medium is said to be stable at this temperature. In the case of 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 by a conventional method.

[0485] In a first preferred embodiment, the medium according to the invention has a clearing temperature of 90 °C or higher, preferably 100 °C or higher, more preferably 105 °C or higher, in particular 108 °C or higher.

[0486] In a preferred embodiment, the liquid crystal mixture according to the invention has a dielectric anisotropy Δε of -2.0 to -6.0, preferably -2.2 to -5.0, in particular -2.4 to -4.3.

[0487] The rotational viscosity γ at 20 °C 1 is preferably in the range of 100 to 250 mPas, more preferably in the range of 120 to 230 mPa·s.

[0488] The medium according to the present invention contains a compound of formula I at a concentration in the range of 0.1% to 10%, preferably 0.5% to 8%, more preferably 1% to 7%, and most preferably 1.5% to 6%.

[0489] Preferred embodiments are as follows, either alone or in combination.

[0490] The medium preferably is:

[0491] ·One or more compounds of formula IIA, preferably IIA-10, more preferably one or more compounds CCY-n-Om, especially CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, at a total concentration preferably in the range of 3% to 25%, more preferably 6% to 20%, and particularly preferably 8% to 15%; and / or

[0492] ·A compound selected from one or more compounds of formula IID, preferably compounds of formula IID-4 and IID-10, at a total concentration preferably in the range of 2% to 40%, more preferably 15% to 35%, and particularly preferably 20% to 30%; and / or

[0493] ·One or more compounds of formula IID-4, preferably CLY-n-Om, especially CLY-2-O4, CLY-3-O2 and / or CLY-3-O3, at a total concentration preferably in the range of 3% to 38%, more preferably 8% to 25%, and particularly preferably 10% to 20%; and / or

[0494] ·One or more compounds of formula IID-10, preferably CLOY-n-Om, especially CLOY-3-O2, at a total concentration preferably in the range of 2% to 35%, more preferably 4% to 30%, and particularly preferably 6% to 26%; and / or

[0495] ·One or more compounds of formula IIB less than 5%, more preferably less than 3%, and very preferably less than 1%; and / or

[0496] ·One or more compounds of formula IIC of less than 5%, more preferably less than 3%, and most preferably less than 1%; and / or

[0497] ·One or more compounds of formula III, preferably formula III-2 and / or III-3, more preferably formula III-2-6 and / or III-3, particularly the compounds B(S)-nO-Om and / or COB(S)-n-Om, most particularly B(S)-2O-O4, B(S)-2O-O5, B(S)-2O-O6, and / or COB(S)-2-O4, at a total concentration preferably in the range of 1% to 20%, more preferably 2% to 17%, and most preferably 4% to 15%; and / or

[0498] ·One or more compounds selected from formula III and / or PH-1, preferably formula III-2 and / or BP-3, more preferably formula III-2-6, particularly B(S)-2O-O4, B(S)-2O-O5, and B(S)-2O-O6, at a total concentration preferably in the range of 1% to 12%, more preferably 2% to 11%, and most preferably 3% to 10%; and / or

[0499] ·One or more compounds of formula III, preferably formula III-2 and III-3, more preferably formula III-2-6 and III-3, particularly one or more compounds B(S)-nO-Om and COB(S)-n-Om, most particularly B(S)-2O-O4, B(S)-2O-O5, B(S)-2O-O6, and COB(S)-2-O4, at a total concentration preferably in the range of 4% to 20%, more preferably 6% to 14%, and most preferably 8% to 12%; and / or

[0500] ·One or more compounds of formula IV at a total concentration preferably in the range of 25% to 70%, more preferably 30% to 60%, and particularly preferably 35% to 55%; and / or

[0501] ·One or more compounds of formula VI-1, preferably formula IV-1-6, preferably at a total concentration in the range of 1% to 20%, more preferably 2% to 18%, very preferably 3% to 15%; and / or

[0502] ·One or more compounds of formula CC-3-V1 and / or CC-4-V1 at a total concentration in the range of 5% to 35%, more preferably 10% to 28%, particularly preferably 12% to 26%; and / or

[0503] ·One or more compounds of formula IV-3-1, preferably CC-3-V and / or CC-4-V, preferably at a total concentration in the range of 1% to 25%, more preferably 2% to 22%, very preferably 3% to 20%; and / or

[0504] ·One or more compounds of formula IVa, more preferably formula IVa-2, particularly the compound CP-3-O2, at a total concentration in the range of 0.5% to 8%, more preferably 1% to 6%, very preferably 2% to 5%; and / or

[0505] ·One or more compounds selected from compounds of formula V, more preferably formula V-2-1 and V-2-2, particularly selected from the group consisting of CCP-n-m and / or CCP-Vn-m and / or CPP-n-m, very particularly CCP-3-1, CCP-V-1, CCP-V2-1 and CPP-3-2, preferably at a total concentration in the range of 1% to 20%, more preferably 2% to 17%, very preferably 3% to 14%; and / or

[0506] ·A compound selected from one or more compounds of formula V-1-1 and V-1-6, particularly CCC-n-m and / or CCC-n-V, very particularly CCC-3-V and / or CCC-V-V, preferably at a total concentration in the range of 1% to 20%, more preferably 2% to 17%, extremely preferably 3% to 14%; and / or

[0507] ·One or more compounds selected from the group consisting of formula CL, more preferably formula CL-3, and particularly preferably compounds CLP-V-m, CLP-V-Om, CLP-n-m, and CLP-n-Om (wherein n and m are independently 1, 2, 3, 4, or 5), preferably in a total concentration in the range of 1% to 12%, more preferably 2% to 10%, and very preferably 3% to 7%; and / or

[0508] ·One or more compounds of formula COYOIC-n-m; and / or

[0509] ·One or more compounds of formula CCOY-n-Om; and / or

[0510] ·Contains 0.1% to 3% of compound PPGU-3-F.

[0511] The liquid crystal medium according to the present invention has a high voltage holding ratio in a liquid crystal cell.

[0512] Generally, a liquid crystal medium having a low address voltage or threshold voltage exhibits a lower voltage holding ratio than one having a high address voltage or threshold voltage, and vice versa.

[0513] As used herein, the term "dielectrically positive compound" refers to a compound having a Δε greater than 1.5, the term "dielectrically neutral compound" refers to one having a Δε between -1.5 and 1.5, and the term "dielectrically negative compound" refers to one having a Δε less than -1.5. The dielectric anisotropy of a compound is determined by measuring the capacitance of a mixture obtained by dissolving 10% of the compound in a liquid crystal host at 1 kHz in at least one test cell having a homeotropic and a homogeneous surface alignment each having a layer thickness of 20 μm. The measurement voltage is typically 0.5 V to 1.0 V, but is always lower than the capacitance threshold of the liquid crystal mixture being considered.

[0514] All temperature values shown in the present invention are in °C.

[0515] The mixtures according to the present invention are suitable for all VA-TFT applications, such as VAN, MVA, (S)-PVA, ASV, PSA (polymer sustained VA), and PS-VA (polymer stabilized VA). They are further suitable for IPS (in-plane-switching) and FFS (fringe field switching) applications having a negative Δε, particularly UB-FFS.

[0516] It goes without saying for those skilled in the art that the VA, IPS, or FFS mixtures of the present invention may also include compounds in which H, N, O, Cl, and F are substituted with the corresponding isotopes.

[0517] The compounds according to the present 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 by methods similar thereto under known reaction conditions suitable for the said reactions. Although not mentioned herein, variations known per se can be used in the present specification. In particular, they can be prepared by methods described in or similar to the following reaction schemes. Further methods for preparing the compounds of the present invention can be obtained from the examples.

[0518] Other mesogenic compounds not explicitly mentioned above can also advantageously be used in the media according to the present invention. Such compounds are known to those skilled in the art.

[0519] In the present invention and the following examples, the structures of the liquid crystal compounds are indicated by acronyms, and the conversion to chemical formulas is carried out according to Tables A to C below. All groups Cm H 2m+1 、C n H 2n+1 、およびC l H 2l+1 またはC m H 2m-1 、C n H 2n-1 およびandC l H 2l-1 is a linear alkyl group or alkylene group having n, m, and l carbon atoms, respectively, in each case. Preferably, n, m, and l are each independently 1, 2, 3, 4, 5, 6, or 7. Table A shows the codes of the ring elements of the nucleus of the compound, Table B lists the cross-linking units, and Table C lists the meanings of the symbols of the left and right end groups of the molecule. The acronym is composed of the code of the ring element having any linking group followed by the first hyphen and the code of the left end group, and the second hyphen and the code of the right end group. Table D shows examples of the structures of the compounds together with their respective abbreviations.

[0520] <Table A: Ring Elements>

[0521]

Table 1

[0522]

Table 2

[0523]

Table 3

[0524] <Table B: Cross-Linking Units>

[0525]

Table 4

[0526] <Table C: Terminal Groups>

[0527] [Table 5]

[0528] [Table 6] In the table, n and m are each integers, and the three dots "..." are places for other abbreviations from this table.

[0529] Apart from the compounds of formula I, IIA, IIB, IIC and / or IID, IVa, IVb and V, the mixtures according to the invention may comprise one or more compounds of the compounds mentioned below.

[0530] The following abbreviations are used: (n, m, k and l are each independently an integer, preferably 1 to 9, preferably 1 to 7; 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".)

[0531]

[0532] [Table 7]

[0533] [Table 8]

[0534] [Table 9]

[0535]

Table 10

[0536]

Table 11

[0537]

Table 12

[0538]

Table 13

[0539]

Table 14

[0540]

Table 15

[0541]

Table 16

[0542]

Table 17

[0543]

Table 18

[0544]

Table 19

[0545]

Table 20

[0546]

Table 21

[0547]

Table 22

[0548]

Table 23

[0549]

Table 24

[0550]

Table 25

[0551]

Table 26

[0552]

Table 27

[0553]

Table 28

[0554]

Table 29

[0555]

Table 30

[0556]

Table 31

[0557] Table E shows exemplary reactive mesogen compounds that can be used in the LC medium according to the present invention.

[0558]

Table 32

[0559]

Table 33

[0560]

Table 34

[0561]

Table 35

[0562]

Table 36

[0563]

Table 37

[0564]

Table 38

[0565]

Table 39

[0566]

Table 40

[0567]

Table 41

[0568]

Table 42

[0569]

Table 43

[0570]

Table 44

[0571]

Table 45

[0572]

Table 46

[0573]

Table 47

[0574]

Table 48

[0575]

Table 49

[0576]

Table 50

[0577]

Table 51

[0578]

Table 52

[0579] In a preferred embodiment, the mixture according to the present invention preferably contains one or more polymerizable compounds selected from the polymerizable compounds of formulas RM-1 to RM-182. Among these, compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-58, RM-64, RM-74, RM-76, RM-88, RM-91, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-140, RM-142, RM-143, RM-145, RM-146, RM-147, RM-149, RM-156 to RM-163, RM-169, RM-170 and RM-171 to RM-184 are particularly preferred.

Examples

[0580] The present invention will be described in detail by the following non-limiting examples.

[0581] The following abbreviations and symbols are used: V0 is the capacitance threshold voltage [V] at 20 °C, n e is the abnormal 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 [°C], γ1 is the rotational viscosity [mPa·s] at 20 °C, K1 is the elastic constant [pN] for the "splay" deformation at 20 °C, K2 is the elastic constant [pN] for the "twist" deformation at 20 °C, K3 is the elastic constant [pN] for the "bend" deformation at 20 °C, K av is K at 20 °C av = 1 / 3(1.5K1 + K3) represents the average elastic constant [pN] defined as such.

[0582] Unless otherwise explicitly stated, all concentrations in this application are quoted in weight percent and relate to the corresponding mixture consisting of all solid or liquid crystal components without solvent.

[0583] Unless otherwise explicitly stated, all temperature values shown in this application, such as the melting point T(C,N), the transition T(S,N) from the smectic (S) phase to the nematic (N) phase, and the clearing point T(N,I), are quoted in degrees Celsius (°C). M.p. 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 temperature.

[0584] All physical properties are determined or have been determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", November 1997 issue, Merck, Germany, applied for a temperature of 20 °C, and Δn is determined at 589 nm and Δε is determined at 1 kHz unless explicitly indicated otherwise in each case.

[0585] For the present invention, unless otherwise specified, the term "threshold voltage" relates to the capacitance threshold (V0), also known as the Frederiks threshold. Also, in the examples, although generally normal, the optical threshold for 10% relative contrast (V 10 ) may also be shown.

[0586] Unless otherwise stated, the polymerization process of the polymerizable compound in the PSA display as described above and below is carried out at a temperature at which the LC medium exhibits a liquid crystal phase, preferably a nematic phase, and most preferably at room temperature.

[0587] Unless otherwise stated, the method for preparing test cells and the method for measuring their electro-optical and other properties are carried out in a manner as described hereinafter or similar thereto.

[0588] The display used for measuring the capacitance threshold voltage consists of two plane-parallel glass outer plates with a 25 μm gap, each having an electrode layer on the inner side and an unrubbed polyimide alignment layer on the upper side that provides a homeotropic alignment of liquid crystal molecules.

[0589] The display or test cell used for measuring the tilt angle consists of two plane-parallel glass outer plates with a 4 μm gap, each having an electrode layer on the inner side and a polyimide alignment layer on the upper side, provided that the two polyimide layers are rubbed antiparallel to each other, resulting in a homeotropic edge alignment of liquid crystal molecules.

[0590] The polymerizable compound is polymerized by irradiating it with UV light of a specified intensity in the display or test cell for a predetermined time while a voltage is applied to the display (usually 10 V - 30 V AC, 1 kHz). Unless otherwise indicated in the examples, a fluorescent lamp and an intensity of 0 - 20 mW / cm 2 are used for polymerization. The intensity is measured using a standard meter (Ushio Accumulate UV meter with a central wavelength of 313 nm).

[0591] The transmittance measurement is carried out in a test cell having a fishbone electrode layout (manufactured by Merck KGaA, Japan; 1-pixel fishbone electrode (ITO, 10×10 mm, fishbone angle 47.7° with 3 μm line / 3 μm space), 3.2 μm cell gap, AF glass, tilt angle 1°).

[0592] The storage stability (LTS bulk ) in the bulk of the medium according to the present invention at a predetermined temperature T is determined by visual inspection. 2 g of the target medium is filled into a sealed glass container (bottle) of appropriate size and placed in a refrigerator at a predetermined temperature. The bottle is checked at defined time intervals for the occurrence of a smectic phase or crystallization. For all materials and for each temperature, two bottles are stored. If crystallization or the appearance of a smectic phase is observed in at least one of the two corresponding bottles, the test is terminated and the time of the last inspection before the occurrence of a higher-order phase is observed is recorded as the respective storage stability.

[0593] <Compound Example 1> 1-(4-Ethylcyclohexyl)-4-[4-(4-propylcyclohexyl)cyclohex-1-en-1-yl]benzene

[0594]

Chemical Structure

[0595] 1-(4-Ethylcyclohexyl)-4-[4-(4-propylcyclohexyl)cyclohex-1-en-1-yl]benzene is prepared by adding [4-(4-ethylcyclohexyl)phenyl]magnesium bromide to 4'-propyl-[1,1'-bi(cyclohexane)]-4-one to obtain the intermediate 4-[4-(4-ethylcyclohexyl)phenyl]-4'-propyl-[1,1'-bi(cyclohexane)]-4-ol, and then eliminating water. Phase series: K239N290I Δε = 0.5 Δn = 0.1352

[0596] <Compound Example 2> 1-(4-Ethylcyclohexyl)-2-fluoro-4-[4-(4-propylcyclohexyl)cyclohex-1-en-1-yl]benzene

[0597]

Chemical Structure

[0598] <Mixture Example> Comparative Example C1 and Mixtures M1 to M15 and P1 to P10 have the compositions and physical properties shown in the following table. The amounts in the table are shown in weight percent.

[0599] <Comparative Mixture Example C1>

[0600]

Table 53

[0601] <Mixture Example M1>

[0602]

Table 54

[0603] The following table summarizes the main parameters of Mixtures C1 and M1.

[0604]

Table 55

[0605] Surprisingly, by using the compound of formula I of Mixture Example 1, despite the higher clearing temperature, a preferably low rotational viscosity (γ 1 ) is achieved simultaneously with a very low specific γ 1 / K1, and it has been found that the response time of the display is improved.

[0606] <Mixture Example M2>

[0607]

Table 56

[0608] <Mixture Example M3>

[0609]

Table 57

[0610] <Mixture Example M4>

[0611]

Table 58

[0612] <Mixture Example M5>

[0613]

Table 59

[0614] <Mixture Example M6>

[0615]

Table 60

[0616] <Mixture Example M7>

[0617]

Table 61

[0618] <Mixture Example M8>

[0619]

Table 62

[0620] <Mixture Example M9>

[0621]

Table 63

[0622] <Mixture Example M10>

[0623]

Table 64

[0624] <Mixture Example M11>

[0625]

Table 65

[0626] <Mixture Example M12>

[0627]

Table 66

[0628] <Mixture Example M13>

[0629]

Table 67

[0630] <Mixture Example M14>

[0631]

Table 68

[0632] <Mixture Example M15>

[0633]

Table 69

[0634] <Mixture Example M16>

[0635]

Table 70

[0636] <Polymerizable Mixture> The polymerizable mixtures P1 to P9 are prepared from the nematic mixtures given in Table 1 by adding a reactive mesogen (RM) selected from the group of compounds of the formulas RM-1, RM-17, RM-35, RM-64 and RM-171 in the amounts (%RM) given in Table 1.

[0637]

Table 71

[0638] <Table 1: Polymerizable Mixture>

[0639]

Table 72

[0640] <Mixture Example P11> The polymerizable mixture P11 consists of 99.434% of mixture example M1, 0.300% of RM-1, 0.200% of RM-145, 0.050% of RM-163, 0.001% of Irganox® 1076 and 0.015% of compound ST-3a-1.

[0641]

Chemical Formula

[0642]

Chem.

Claims

1. A liquid crystal medium containing one or more compounds of formula I. 【Chemical 1】 (In the formula, R １１ and R １２ are, independently of one another, identical or different and represent H, a straight-chain alkyl or alkoxy having 1 to 15 C atoms, a straight-chain alkenyl or alkenyloxy having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy each having 3 to 15 C atoms, where one or more CH ２ groups in these groups are, independently of one another, such that O atoms are not directly linked to one another 【Chemical 2】 -CH=CH-, -C≡C-, -CF ２ O-, -OCF ２ -,-O-,-CO-O- or -O-CO- and may be substituted, and one or more H atoms in the group may be replaced by halogen atoms, L １１ and L １２ One of them represents H, and L １１ and L １２ The other represents H, F, Cl, CF ３ or CHF ２ .)

2. The liquid crystal medium according to claim 1, wherein the medium contains one or more compounds selected from the group of compounds of formulae IIA, IIB, IIC and IID. [Chemical Formula 3] (In the formula, R ２Ａ , R ２Ｂ , R ２Ｃ and R ２Ｄ are, independently of one another, the same or different and represent H, a linear alkyl or alkoxy having 1 to 15 C atoms, a linear alkenyl or alkenyloxy having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy each having 3 to 15 C atoms, provided that one or more CH ２ groups are, independently of one another, such that O atoms are not directly linked to one another 【Chemical 4】 -CH=CH-, -C≡C-, -CF ２ O-, -OCF ２ -,-O-,-CO-O- or -O-CO- and may be substituted, and one or more H atoms in the group may be replaced by a halogen atom, L １ and L ２ are, independently of each other, F, Cl, CF ３ or CHF ２ and represent Y represents H, F, Cl, CF ３ , CHF ２ or CH ３ and Z ２ 、Z ２Ｂ and Z ２Ｄ each independently represents 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 -, -CF=CF- or -CH=CHCH ２ O-; (O) represents O or a single bond, p represents 0, 1 or 2, q represents 0 or 1, and v represents an integer from 1 to 6.)

3. The liquid crystal medium according to claim 1 or 2, wherein the medium contains one, two or more of the compounds of formula IID as defined in claim 2.

4. The liquid crystal medium according to any one of claims 1 to 3, wherein the medium contains one or more compounds of formula III. 【Chemical Formula 5】 (In the formula, R ３１ and R ３２ each independently represents H, an alkyl or alkoxy group having 1 to 15 C atoms, provided that one or more CH ２ groups in these groups are arranged such that O atoms are not directly linked to each other 【Chemical Formula 6】 -CH=CH-, -C≡C-, -CF ２ O-, -OCF ２ -, -O-, -CO-O- or -O-CO-, may each be independently replaced with each other, and one or more H atoms in the group may be replaced with halogen, A ３１ is, in each occurrence, independent of each other a) a 1,4-cyclohexenylene or 1,4-cyclohexylene group, in which one or two non-adjacent CH ２ groups may be replaced by -O- or -S-. b) a 1,4-phenylene group (in which one or two CH groups may be replaced by N), or c) a group selected from the group of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, provided that the groups a), b) and c) may be mono- or polysubstituted by halogen atoms, Z ３１ is, independently of each other at each occurrence, -CO-O-, -O-CO-, -CF ２ O-, -OCF ２ -, -CH ２ O-, -OCH ２ -, -CH ２ -, -CH ２ CH ２ -, -(CH ２ ) ４ -, -CH=CH-CH ２ O-, -C ２ F ４ -, -CH ２ CF ２ -, -CF ２ CH ２ -, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, L ３１ and L ３２ each independently represents F, Cl, CF ３ or CHF ２ and W represents O or S, and n is 0, 1 or 2.)

5. The liquid crystal medium according to any one of claims 1 to 4, wherein the medium contains one or more compounds selected from the group of compounds of formulae BC, CR, PH-1 and PH-2. [Chemical Formula 7] (In the formula, R Ｂ１ 、 R Ｂ２ 、 R ＣＲ１ 、 R ＣＲ２ 、 R Ｐ１ and R Ｐ２ each independently represents an alkyl or alkoxy group having H, 1 to 15 C atoms, provided that one or more CH ２ groups in these groups are arranged so that O atoms are not directly linked to each other. 【Chemical 8】 -CH=CH-, -C≡C-, -CF ２ O-, -OCF ２ -, -O-, -CO-O- or -O-CO-, may each be independently replaced with each other, and one or more H atoms in the group may be replaced with halogen, c is 0, 1 or 2.)

6. The liquid crystal medium according to any one of claims 1 to 5, wherein the medium contains one or more compounds of formula IV. 【Chemical Formula 9】 (In the formula, R ４１ represents alkyl having 1 to 7 carbon atoms or alkenyl having 2 to 7 carbon atoms, R ４２ represents alkyl having 1 to 7 carbon atoms, alkoxy having 1 to 6 carbon atoms, or alkenyl having 2 to 7 carbon atoms.)

7. The liquid crystal medium according to any one of claims 1 to 6, wherein the medium contains one or more compounds of formula V. 【Chemical 10】 (In the formula, R ５１ 、R ５２ are the same or different and represent 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, 【Chemical 11】 represents, Z ５１ and Z ５２ are the same or different and are —CH ２ —CH ２ —, —CH ２ —O—, —CH═CH—, —C≡C—, —COO— or a single bond, and n is 1 or 2, provided that the compound of formula I of claim 1 is excluded.)

8. The liquid crystal medium according to any one of claims 1 to 7, wherein the medium contains a polymerizable compound.

9. The liquid crystal medium according to any one of claims 1 to 8, wherein the medium has a clearing temperature of 100 °C or higher.

10. A method for producing a liquid crystal medium according to any one of claims 1 to 9, comprising the step of mixing one or more compounds of formula I with one or more compounds selected from the group of formulae IIA, IIB, IIC and IID, and optionally a polymerizable compound or a further liquid crystal compound or additive.

11. A liquid crystal display comprising the liquid crystal medium according to any one of claims 1 to 9.

12. The liquid crystal display according to claim 11, wherein the display is a VA, IPS, FFS, PS-VA, PS-IPS or PS-FFS type display.

13. A compound of formula I. 【Chemical Formula 12】 (wherein, R １１ and R １２ are, independently of one another, H, a linear alkyl, alkoxy having 1 to 15 C atoms or a linear alkenyl or alkenyloxy having 2 to 15 C atoms, or a branched alkyl, alkoxy, alkenyl or alkenyloxy each having 3 to 15 C atoms, provided that one or more CH ２ groups, independently of one another, are such that O atoms are not directly linked to one another 【Chemical 13】 -CH=CH-, -C≡C-, -CF ２ O-, -OCF ２ -,-O-,-CO-O- or -O-CO- and may be substituted, and one or more H atoms in the group may be replaced by a halogen atom, L １１ and L １２ One of them represents H, and L １１ and L １２ The other represents F, Cl, CF ３ or CHF ２ .)

14. A process for preparing a compound of formula I according to claim 13, which comprises a step of removing water from at least the compound of formula (3). 【Chemical 14】 (wherein, R １１ 、 R １２ 、 L １１ and L １２ have the meaning of formula I according to claim 13.

15. A compound of formula (3) as defined in claim 14.

Images