Liquid-crystal medium comprising polymerizable compound

Abstract

To provide a liquid-crystal medium comprising a polymerizable compound.SOLUTION: The present invention relates to a liquid-crystal (LC) medium comprising a polymerizable compound, and to the use of the LC medium for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the PSA (polymer sustained alignment) or SA (self-aligning) mode, to an LC display of the PSA or SA mode comprising the LC medium, and to a process of manufacturing the LC display.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid-crystal (LC) medium comprising a polymerizable compound and to its use for optical, electro-optical and electronic purposes, in particular in LC displays, in particular in PSA (polymer sustained alignment) or SA (self-aligning) mode LC displays, to PSA or SA mode LC displays comprising said LC medium, and to a method for producing said LC displays. [Background technology]

[0002] The popularity of 8K monitors and gaming monitors has led to an increased demand for liquid crystal display (LCD) panels with higher refresh rates, and therefore faster response times. Many of these LCD panels use polymer-stabilized (PS) or polymer-sustained alignment (PSA) modes, such as PS-VA (vertically aligned), PS-IPS (in-plane switching), or PS-FFS (fringe-field switching) modes, or derivative modes, or self-aligned (SA) modes, such as polymer-stabilized SA-VA.

[0003] In the PS or PSA mode, small amounts, typically 0.1-1%, of one or more polymerizable mesogenic compounds, also known as RMs (reactive mesogens), are added to the LC medium. After the LC medium is filled into a display, the RMs are then polymerized in situ by UV photopolymerization while a voltage is applied to the display's electrodes. This creates a small tilt angle in the LC molecules of the LC medium, which is stabilized by the polymerized RMs. The UV polymerization process, also known as the "PSA process," is typically a two-step process, involving a first UV exposure step ("UV1 step") in which a voltage is applied to create the tilt angle, and a second UV exposure step ("UV2 step") in which no voltage is applied to complete the polymerization of the RMs.

[0004] In the SA-VA mode, alignment layers are omitted from the display. Instead, small amounts, typically 0.1-2.5%, of self-aligning (SA) additives are added to the LC medium, which induce the desired alignment, e.g., homeotropic or planar alignment, in situ through a self-assembly mechanism. SA additives typically contain an organic mesogenic core group to which one or more polar anchoring groups, such as hydroxy, carboxy, amino, or thiol groups, are attached, which can interact with the substrate surface, aligning the additive on the substrate surface and inducing the desired alignment in the LC molecules. SA additives may also contain one or more polymerizable groups that can polymerize under conditions similar to those of the RMs used in the PSA process. In addition to the SA additive, the LC medium may also contain one or more RMs.

[0005] One way to shorten the response time of LC media for PSA mode is to use compounds with alkenyl groups as components of the LC host mixture. However, this can lead to a decrease in the reliability of the mixture when exposed to the UV light required for the polymerization of the RM additives. This is thought to be due to the alkenyl compounds reacting with the polyimide in the alignment layer, which is particularly problematic when UV wavelengths shorter than 320 nm are used. Therefore, there is a trend toward using longer UV wavelengths in PSA processes.

[0006] Another way to shorten the response time of LC media for PSA mode is to adjust the cell gap to a higher / lower one. This can be achieved by adjusting the dielectric constant (ε) of highly polar LC compounds, especially those with a high dielectric constant perpendicular to the director. ⊥ ) may need to be used. However, these compounds can have a negative effect on the reliability of the LC medium. Therefore, to change the cell gap and thereby reduce the response time, it is important to find the right balance between sufficient polarity of the LC medium on the one hand and high reliability of the LC medium on the other hand.

[0007] There is therefore a need for polymerizable LC media for use in PSA or SA displays that have high resistivity, as well as a wide operating temperature range, short response times even at low temperatures, low threshold voltages, low tilt angles, high tilt stability, a large number of grey levels, high contrast, and wide viewing angles, high reliability after UV exposure and high values ​​of VHR, and, in the case of polymerizable compounds, low melting points and high solubility in LC host mixtures, and are polymerizable even at longer UV wavelengths. For displays intended for mobile applications, it is particularly desirable to have available LC media that exhibit low threshold voltages and high birefringence. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention is based on the object of providing new suitable materials, in particular RMs and LC media containing them, which do not have the above-mentioned disadvantages or have them to a reduced extent for use in PSA or SA displays.

[0009] In particular the present invention comprises RMs for use in PSA or SA displays, and is based on the objective of an LC medium which allows for very high resistivity, high VHR, high reliability, low threshold voltage, short response time, high birefringence, exhibits good UV absorption even at longer UV wavelengths, preferably in the range of 340-380 nm, allows for fast and complete polymerization of the RM, preferably produces low tilt angles as quickly as possible, allows for high tilt angle stability even over time and / or after UV exposure, reduces or prevents the occurrence of "image sticking" and "ODF mura" in the display, polymerizes as quickly and completely as possible in the case of the RM, and exhibits high solubility in LC media typically used as host mixtures in PSA or SA displays.

[0010] It is a further object of the present invention to provide an LC medium for use in PSA displays, wherein the RM exhibits both a fast polymerization rate and good reliability parameters such as high VHR or tilt stability.

[0011] It is a further object of the present invention to provide novel LC media containing RMs, in particular for optical, electro-optical and electronic applications, as well as suitable processes and intermediates for their preparation. [Means for solving the problem]

[0012] It has now been found that one or more of these objects can be achieved by providing the LC media disclosed and claimed hereinafter.

[0013] The invention therefore relates to an LC medium having negative dielectric anisotropy and comprising one or more polymerizable compounds, one or more compounds of the formula IA and one or more compounds of the formula IB.

[0014] [ka]

[0015] In the formula, the individual radicals, which are identical or different at each occurrence, each have the following meaning independently of one another: R 1 , R 2 is a linear, branched or cyclic alkyl having 1 to 25 carbon atoms (provided that one or more non-adjacent CH groups are not directly linked to each other by O atoms and / or S atoms, respectively, and are -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-, [ka] wherein one or more H atoms may be replaced by F or Cl, respectively), preferably alkyl or alkoxy having 1 to 6 C atoms, R 0 , R 00 is H or alkyl having 1 to 12 C atoms, L 1 , L 2 is F or Cl, preferably F.

[0016] The invention further relates to the use of an LC medium as described above and below in a PSA or SA mode LC display.

[0017] 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 polymerizable compounds with one or more compounds of formulae IA and IB, and optionally further LC compounds and / or additives.

[0018] The invention further relates to an LC display comprising an LC medium according to the invention as described above and below, which is a PSA or SA display, preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0019] The present invention further relates to an LC display comprising an LC medium as described above and below, in which the polymerizable compound is present in polymerized form, preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0020] The invention further relates to a PSA type LC display comprising two substrates, at least one of which is transparent to light, an electrode on each substrate or two electrodes on only one substrate, and a layer of an LC medium as described above and below, arranged between the substrates, wherein the polymerizable compound is polymerized between the substrates of the display by UV photopolymerization.

[0021] The present invention further relates to a method for producing an LC display as described above and below, which comprises the steps of filling or otherwise providing an LC medium as described above and below between the substrates of the display, and polymerizing the polymerizable compound, preferably while applying a voltage to the electrodes of the display.

[0022] The present invention further relates to a method for producing an LC display as described above and below, wherein the irradiation of the polymerizable compound is carried out using a UV-LED lamp.

[0023] The LC media according to the invention exhibit one or more of the following advantageous properties when used in PSA displays: High transmittance, High contrast ratio, Reduced image sticking, Reduced ODF unevenness, Reduced rotational viscosity, High reliability and high VHR values ​​after UV exposure and / or heat treatment, Fast response time, The ratio of rotational viscosity to splay elastic constant γ1 / K1 is advantageously small, which contributes to improved switching behavior, especially at low driving voltages, and is useful for realizing energy-saving displays. Low threshold voltage, which is useful for realizing energy-saving displays, Good UV photopolymerization even when using low-radiant UV light sources and / or long UV emission wavelengths such as UV LED lamps or green UV lamps, minimizing production costs and saving energy; Fast polymerization with minimal residual RM after UV processing Good tilt stability. DETAILED DESCRIPTION OF THE INVENTION

[0024] Alkenyl groups in the compounds of formula IA, IB, II as disclosed below or in other components of the LC medium are not considered to be within the meaning of the term "polymerizable group" as used herein. The polymerization conditions of the polymerizable compounds of the LC medium are preferably selected so that the alkenyl substituents do not participate in the polymerization reaction. Preferably, the LC media disclosed and claimed in this application do not contain additives that initiate or promote the participation of alkenyl groups in the polymerization reaction.

[0025] Unless otherwise specified, the polymerizable compound and the compound of formula II are preferably selected from achiral compounds.

[0026] As used herein, the expression "UV light having a wavelength of" followed by a predetermined wavelength range (in nm) or a predetermined lower or upper wavelength limit (in nm) means that the UV emission spectrum of the respective radiation source has an emission peak that is preferably the highest peak in the respective spectrum within the predetermined wavelength range or above the predetermined lower wavelength limit or below the predetermined upper wavelength limit, and / or that the UV absorption spectrum of the respective chemical has a long or short wavelength tail that extends within the predetermined wavelength range or above the predetermined lower wavelength limit or below the predetermined upper wavelength limit.

[0027] As used herein, the term "substantially transmit" means that the filter transmits a majority of incident light of a desired wavelength, preferably at least 50% intensity. As used herein, the term "substantially block" means that the filter does not transmit a majority of incident light of undesired wavelengths, preferably at least 50% intensity. As used herein, the term "desired (undesired) wavelength" means, for example, in the case of a bandpass filter, a wavelength within (outside) a given λ range, and in the case of a cutoff filter, a wavelength above (below) a given λ value.

[0028] As used herein, the terms "active layer" and "switchable layer" refer to a layer in an electro-optical display, e.g., an LC display, that contains one or more types of molecules with structural and optical anisotropy, e.g., LC molecules, that undergo a change in molecular orientation upon application of an external stimulus, such as an electric or magnetic field, resulting in a change in the transparency of the layer for polarized or unpolarized light.

[0029] As used herein, the terms "tilt" and "tilt angle" are understood to mean the tilted orientation of the LC molecules of the LC medium in an LC display (herein preferably a PSA display) relative to the cell surface. As used herein, tilt angle means the average angle (less than 90°) between the molecular long axis (LC director) of the LC molecules and the surfaces of the flat, parallel outer plates forming the LC cell. As used herein, low values ​​of tilt angle (i.e., large deviations from the 90° angle) correspond to large tilt. A suitable method for measuring tilt angle is given in the examples. Unless otherwise indicated, the tilt angle values ​​disclosed above and below refer to this measurement method.

[0030] As used herein, the terms "reactive mesogen" and "RM" are understood to mean a compound containing a mesogenic or liquid crystalline backbone and one or more functional groups attached to the backbone that are suitable for polymerization, which functional groups are also referred to as "polymerizable groups" or "P".

[0031] Unless otherwise stated, as used herein, the term "polymerizable compound" is understood to mean a polymerizable monomeric compound.

[0032] The SA-VA displays according to the present invention are polymer-stabilized mode displays that comprise or are produced using an LC medium comprising an RM such as those described below. Consequently, as used herein, the term "SA-VA display" when referring to a display according to the present invention is understood to refer to a polymer-stabilized SA-VA display, even if not explicitly stated otherwise.

[0033] As used herein, the term "low molecular weight compound" is understood as a term in contrast to "polymeric compound" or "polymer" to mean a compound that is monomeric and / or not prepared by a polymerization reaction.

[0034] As used herein, the term "non-polymerizable compound" is understood to mean a compound that does not contain functional groups suitable for polymerization under conditions normally applied for the polymerization of RMs.

[0035] As used herein, the term "mesogenic group" is known to those skilled in the art and described in the literature and refers to a group that, due to the anisotropy of its attractive and repulsive interactions, essentially contributes to the generation of a liquid crystal (LC) phase in low-molecular-weight or polymeric materials. A compound containing a mesogenic group (mesogenic compound) does not necessarily have an LC phase by itself. It is also possible for a mesogenic compound to exhibit LC phase behavior only after mixing with other compounds and / or polymerization. Typical mesogenic groups are, for example, rigid rod- or disc-shaped units. A review of terms and definitions used in connection with 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.

[0036] As used herein, the term "spacer group", hereinafter also referred to as "Sp", is known to those skilled in the art and described in the literature, see, for example, Pure Appl. Chem. 2001, vol. 73 (No. 5), p. 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, vol. 116, pp. 6340-6368. As used herein, the term "spacer group" or "spacer" refers to a flexible group, such as an alkylene group, that connects a mesogenic group and a polymerizable group(s) in a polymerizable mesogenic compound.

[0037] Above and below, [ka] represents a trans-1,4-cyclohexylene ring, [ka] represents a 1,4-phenylene ring.

[0038] basis [ka] The single bond shown between two ring atoms in can be attached to any free position on the benzene ring.

[0039] In the formulas shown above and below, the group R 1~12 , R QIf R or L represents an alkyl and / or alkoxy group, this may be linear or branched. It is preferably linear and has 2, 3, 4, 5, 6 or 7 C atoms and therefore preferably represents ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexyloxy or heptyloxy, furthermore methyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, methoxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.

[0040] In the formulas shown above and below, the group R 1~12 , R Q , when R or L represents an alkyl group in which one or more CH groups have been replaced by S, this may be linear or branched. It is preferably linear and has 2, 3, 4, 5, 6 or 7 C atoms and therefore preferably represents thiomethyl, thioethyl, thiopropyl, thiobutyl, thiopentyl, thiohexyl or thioheptyl.

[0041] Oxaalkyl preferably represents straight-chain 2-oxapropyl (= methoxymethyl), 2- (= ethoxymethyl) or 3-oxabutyl (= 2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3-, 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

[0042] In the formulas shown above and below, the group R 1~12 , R Q When R or L represents an alkoxy or oxaalkyl group, it may also contain one or more additional oxygen atoms, provided that the oxygen atoms are not directly linked to one another.

[0043] In another preferred embodiment, one or more R 1~12 , R Q , R or L is [ka] -S 1 -F, -OS 1 -F, -O-S1-O-S2 (S in the formula 1 is C 1~12 -Alkylene or C 2~12 -alkenylene, and S 2 is H, C 1~12 -Alkyl or C 2~12 -alkenyl), very preferably [ka] Selected from the group consisting of: -OCH2OCH3, -O(CH2)2OCH3, -O(CH2)3OCH3, -O(CH2)4OCH3, -O(CH2)2F, -O(CH2)3F, -O(CH2)4F.

[0044] In the formulas shown above and below, the group R 1~12 , R Q If R or L represents an alkyl group in which one or more CH groups have been replaced by -CH=CH-, this may be linear or branched. It is preferably linear and has 2 to 10 C atoms. It therefore stands in particular for vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl, oct-1-, -2-, -3-, -4-, -5-, -6- or -7-enyl, non-1-, -2-, -3-, -4-, -5-, -6-, -7- or -8-enyl, dec-1-, -2-, -3-, -4-, -5-, -6-, -7-, -8- or -9-enyl.

[0045] In the formulas shown above and below, the group R 1~12 , R QWhen R or L represents an alkyl or alkenyl group at least monosubstituted with a halogen, the group is preferably linear and the halogen is preferably F or Cl. In the case of polysubstitution, the halogen is preferably F. The resulting group also includes perfluoro groups. In the case of monosubstitution, the fluorine or chlorine substituent may be in any desired position, but is preferably in the ω-position.

[0046] Halogen is preferably F or Cl, very preferably F.

[0047] Group-CR 0 =CR 00 - is preferably -CH=CH-.

[0048] -CO-, -C(=O)- and -C(O)- are carbonyl groups, i.e. [ka] Represents.

[0049] Preferred substituents L 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, linear or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy each having 1 to 25 C atoms (wherein one or more H atoms may be replaced by F or Cl), optionally substituted silyl having 1 to 20 Si atoms, or optionally substituted aryl having 6 to 25, preferably 6 to 15, C atoms,

[0050] In the formula, R xrepresents H, F, Cl, CN, a linear, branched or cyclic alkyl chain having 1 to 25 C atoms, with the proviso that one or more non-adjacent CH groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S- atoms are not directly linked to one another, with the proviso that one or more H atoms may be replaced by F, Cl, P- or P-Sp-, respectively, and

[0051] Y 1 represents a halogen.

[0052] Particularly preferred substituents L are, for example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and also phenyl.

[0053] [ka] wherein L has one of the meanings given above.

[0054] The polymerizable group P is a group suitable for polymerization reactions, such as, for example, free-radical or ionic chain polymerization, polyaddition or polycondensation, or for polymer-analogous reactions, such as, for example, addition or condensation onto a polymer backbone. Groups for chain polymerization, especially those containing a C=C double bond or a C≡C triple bond, and groups suitable for ring-opening polymerization, such as, for example, oxetane or epoxide groups, are particularly preferred.

[0055] The preferred group P is CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, [ka] CH2=CW 2 -(O) k3 -, CW 1 =CH-CO-(O) k3 -, CW 1=CH-CO-NH-, CH2=CW 1 -CO-NH-, CH3-CH=CH-O-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, HO-CW 2 W 3 -, HS-CW 2 W 3 -, HW 2 N-, HO-CW 2 W 3 -NH-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH-, HOOC-, OCN- and W 4 W 5 W 6 Si—, 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 denotes H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 carbon atoms, W 7 and W 8 each independently 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 represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0056] A highly preferred group P is CH2=CW 1 -CO-O-, CH2=CW1 -CO-, [ka] CH2=CW 2 -O-, CH2=CW 2 -, CW 1 =CH-CO-(O) k3 -, CW 1 =CH-CO-NH-, CH2=CW 1 -CO-NH-, (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-, (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-, CH2=CH-(COO) k1 -Phe-(O) k2 -, CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH- and W 4 W 5 W 6 Si—, 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 denotes H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 carbon atoms, 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 of 1 to 10.

[0057] Very particularly preferred groups P are CH2=CW 1-CO-O-, in particular 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-, [ka] is selected from the group consisting of:

[0058] More preferably, the polymerizable group P is selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide groups, most preferably from acrylate and methacrylate.

[0059] Very preferably, all polymerizable groups in the polymerizable compound have the same meaning.

[0060] When the spacer group Sp is different from a single bond, it is preferably of the formula Sp"-X" such that each group P-Sp- corresponds to the formula R-Sp"-X"-, with the proviso that:

[0061] Sp" represents a linear or branched alkylene group having 1 to 20, preferably 1 to 12, C atoms, which may be mono- or polysubstituted by F, Cl, Br, I or CN, provided that in addition, one or more non-adjacent CH groups are each independently -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-, “X” is -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R0 )-, -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 represents -, -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 represents H, F, Cl or CN.

[0062] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, or -CO-NR 0 -, -NR 0 -CO-, -NR 0 -CO-NR 00 - or a single bond.

[0063] Exemplary spacer groups Sp and -Sp"-X"- include, 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 In the formula, p1 is an integer of 1 to 12, q1 is an integer of 1 to 3, and R 0 and R 00 has the meaning given above.

[0064] 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-, wherein p1 and q1 have the meanings given above.

[0065] Particularly preferred radicals Sp" are, in each case linear, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, undecylene, dodecylene, octadecylene, ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene, ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene, propenylene and butenylene.

[0066] In a preferred embodiment of the present invention, the polymerizable compound has the group Sp-P as Sp(P) s (where s is 2 or more) and contains a spacer group Sp (branched polymerizable group) substituted with one or more polymerizable groups P so as to correspond to the above.

[0067] Preferred polymerizable compounds according to this preferred embodiment are those in which s is 2, i.e. compounds containing the group Sp(P)2. Highly preferred polymerizable compounds according to this preferred embodiment contain a group selected from the following formulae:

[0068] [ka]

[0069] wherein P is as defined in Formula I; alkyl represents a single bond or a linear or branched alkylene having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN, provided that one or more non-adjacent CH groups are each independently connected to one another in such a way 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-, provided that R 0 has the meaning given above, aa and bb each independently represent 0, 1, 2, 3, 4, 5, or 6; X has one of the meanings given under X″ and is preferably O, CO, SO2, O—CO—, CO—O or a single bond.

[0070] Preferred spacer groups Sp(P)2 are selected from formulae S1, S2 and S3.

[0071] Highly preferred spacer groups Sp(P)2 are selected from the following sub-formulae:

[0072] [ka]

[0073] In the compounds of formula P and subformulas thereof as described above and below, P is preferably selected from the group consisting of vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxide, most preferably acrylate and methacrylate.

[0074] More preferably, all polymerizable groups P present in the compound have the same meaning, very preferably denoting acrylate or methacrylate, most preferably methacrylate.

[0075] Sp is a single bond or -(CH2)p1 -, -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 wherein p1 is 2, 3, 4, 5 or 6, preferably 2 or 3, p2 and p3 are each independently 0, 1, 2 or 3, and Sp is -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 In the case of , an O atom or a CO group is respectively connected to the benzene ring.

[0076] More preferably, at least one group Sp is a single bond.

[0077] More preferably, 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 wherein p1 is 2, 3, 4, 5 or 6, preferably 2 or 3, p2 and p3 are each independently 0, 1, 2 or 3, and Sp is -O-(CH2) p1 -, -O-CO-(CH2) p1 or -CO-O-(CH2) p1 In the case of , an O atom or a CO group is respectively connected to the benzene ring.

[0078] Highly preferably, Sp is different from a single bond and is selected from (CH2)2-, -(CH2)3-, -(CH2)4-, -O-(CH2)2-, -O-(CH2)3-, -O-CO-(CH2)2 and -CO-O-(CH)2-, where the O atom or CO group is linked to the benzene ring.

[0079] Preferred compounds of formula IA are selected from the group consisting of formulas IA-1 to IA-10:

[0080] [ka]

[0081] [ka]

[0082] In the formula, R 12 represents alkyl having 1 to 7 C atoms, preferably ethyl, n-propyl or n-butyl, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl.

[0083] Preferred compounds of formula IA are selected from the group consisting of formulae IA-1, IA-2, IA-3, IA4 and IA5, very preferably formulae IA-2 and IA-3, most preferably formula IA-2, and in all the foregoing formulae R 12 is preferably ethyl, n-propyl or n-butyl, very preferably n-butyl.

[0084] Preferably the LC medium comprises one, two or three compounds of formula IA or sub-formulas thereof.

[0085] Preferably the total proportion of compounds of formula IA and its subformulas in the LC medium is between 2 and 20% by weight, very preferably between 3 and 14% by weight, most preferably between 4 and 10% by weight.

[0086] Preferred compounds of formula IB are selected from the group consisting of the following subformulae:

[0087] [ka]

[0088] In the formula, alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms, preferably ethyl, n-propyl or n-butyl, and (O) represents an oxygen atom or a single bond, preferably an oxygen atom.

[0089] Compounds of formula IB-1 and IB-2 are very preferred, especially compounds of formula IB-1, in which alkyl represents ethyl, n-propyl or n-butyl, preferably n-propyl, (O) represents an oxygen atom, and alkyl * Most preferred is when represents ethyl, n-propyl or n-butyl, preferably ethyl.

[0090] Preferably the LC medium comprises one, two or three, very preferably one, compound of formula IB or a subformula thereof.

[0091] Preferably the total proportion of compounds of formula IB and its subformulas in the LC medium is between 0.5 and 5%, very preferably between 0.5 and 2% by weight, most preferably between 0.5 and 1.5% by weight.

[0092] Further preferred embodiments of the LC media according to the invention are listed below, including any combination thereof.

[0093] The LC medium comprises one or more compounds of formula II.

[0094] [ka]

[0095] In the formula, the individual radicals each independently of one another have the following meanings, which may be the same or different at each occurrence: R 1 and R 2 is a linear, branched or cyclic alkyl having 1 to 25 carbon atoms (provided that one or more non-adjacent CH groups are not directly linked to each other by O atoms and / or S atoms, respectively, and are -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR 0 =CR 00 -, -C≡C-, [ka] wherein one or more H atoms may be replaced by F or Cl), preferably alkyl or alkoxy having 1 to 6 C atoms, R 0 , R 00 is H or alkyl having 1 to 12 C atoms, A 1 and A 2 is obtained from the following formula: [ka] are preferably groups selected from the formulae A1, A2, A3, A4, A5, A6, A9 and A10, very preferably groups selected from the formulae A1, A2, A3, A4, A5, A9 and A10, Z 1 and Z 2 is —CH2CH2—, —CH═CH—, —CF2O—, —OCF2—, —CHO—, —OCH2—, —CO—O—, —O—CO—, —C2F4—, —CF═CF—, —CH═CH—CHO— or a single bond, preferably a single bond, L 1 , L 2 , L 3 and L 4 is F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F or Cl, very preferably F, Y is H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, very preferably H, L C is CH3 or OCH3, preferably CH3, a1 is 1 or 2, a2 is 0 or 1.

[0096] Preferably the LC medium comprises one or more compounds of formula II selected from the group consisting of compounds of formulae IIA, IIB, IIC and IID.

[0097] [ka]

[0098] During the ceremony R 2A and R 2B are each independently H, an alkyl or alkenyl group having up to 15 C atoms, which is unsubstituted, monosubstituted with CN or CF3, or at least monosubstituted with a halogen, provided that in addition one or more CH2 groups in these groups are -O-, -S-, ... [ka] may be replaced by -C≡C-, -CF2O-, -OCF2-, -CO-O- or -O-CO-; L 1 ~L 4 each independently represents F, Cl, CF3 or CHF2, Y represents H, F, Cl, CF3, CHF2 or CH3, preferably H or CH3, particularly preferably H, Z 2 , Z 2B and Z 2D each independently represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CHO-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, or -CH=CHCHO-; p represents 0, 1 or 2, and q may be the same or different and represents 0 or 1 in each occurrence.

[0099] Preferred compounds of formula IIA, IIB, IIC and IID are R 2B represents an alkyl or alkoxy group having 1 to 15 C atoms, very preferably (O)C v H 2v+1 wherein (O) is an oxygen atom or a single bond, and v is 1, 2, 3, 4, 5, or 6.

[0100] Further preferred compounds of formula IIA, IIB, IIC and IID are 2A or R 2Bis preferably [ka] (S in the formula 1 is C 1~5 -Alkylene or C 2~5 -alkenylene, and S 2 is H, C 1~7 -Alkyl or C 2~7 -alkenyl), and very preferably [ka] and represents or contains a cycloalkyl or cycloalkoxy group selected from the group consisting of:

[0101] More preferred compounds of formula IIA, IIB, IIC and IID are shown below.

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] [ka]

[0107] [ka]

[0108] [ka]

[0109] [ka]

[0110] [ka]

[0111] [ka]

[0112] In the formula, the parameter a represents 1 or 2, and alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 C atoms, alkenyl represents a linear alkenyl group having 2 to 6 C atoms, and (O) represents an oxygen atom or a single bond. Alkenyl preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH-, or CH3-CH=CH-(CH2)2-.

[0113] Particularly preferred LC media according to the invention comprise one or more compounds of the 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 and IID-4

[0114] The proportion of compounds of formula IIA and / or IIB in the overall mixture is preferably at least 20% by weight. In another preferred embodiment the LC medium comprises one or more compounds of formula III which are different from formula IA.

[0115] [ka]

[0116] During the ceremony R 11 and R 12 each independently represent H, an alkyl or alkoxy group having 1 to 15 C atoms, provided that one or more CH groups in these groups are connected in such a way that the O atoms are not directly linked to each other, [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; A 3 occur independently of each other, a) a 1,4-cyclohexenylene or 1,4-cyclohexylene group, in which one or two non-adjacent CH 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 consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl, and fluorene-2,7-diyl represents provided that groups a), b) and c) may be mono- or polysubstituted with halogen atoms; n represents 0, 1 or 2, preferably 0 or 1; Z 1represent, in each occurrence independently of one another, -CO-O-, -O-CO-, -CF2O-, -OCF2-, -C2O-, -OCH2-, -CH2-, -CH2CH2-, -(CH2)4-, -CH=CH-CHO-, -C2F4-, -CH2CF2-, -CF2CH2-, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, and L 11 and L 12 each independently represent F, Cl, CF or CHF, preferably H or F, most preferably F, and W represents O or S.

[0117] In a preferred embodiment of the invention the LC medium comprises one or more compounds of the formulae III-1 and / or III-2

[0118] [ka]

[0119] wherein the occurring radicals have the same meaning as given above in formula III, preferably R 11 and R 12 are each independently an alkyl, alkenyl or alkoxy group having up to 15 C atoms, more preferably one or both of them representing an alkoxy group, L 11 and L 12 each preferably represents F.

[0120] In another preferred embodiment the LC medium comprises one or more compounds of the formula III-1 selected from the group of the compounds of the formulae III-1-1 to III-1-10, preferably of the formula III-1-6:

[0121] [ka]

[0122] [ka]

[0123] In the formula, alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms, and alkenyl and alkenyl * each independently represent a linear alkenyl group having 2 to 6 carbon atoms, alkoxy and alkoxy * each independently represent a linear alkoxy group having 1 to 6 carbon atoms, and L 11 and L 12 each independently represents F or Cl, preferably both represent F.

[0124] In another preferred embodiment the LC medium comprises one or more compounds of the formula III-2 selected from the group of the compounds of the formulae III-2-1 to III-2-10, preferably III-2-6:

[0125] [ka]

[0126] [ka]

[0127] In the formula, alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms, and alkenyl and alkenyl * each independently represent a linear alkenyl group having 2 to 6 carbon atoms, alkoxy and alkoxy * each independently represent a linear alkoxy group having 1 to 6 carbon atoms, and L 11 and L 12 each independently represents F or Cl, preferably both represent F.

[0128] In another preferred embodiment of the invention the LC medium comprises one or more compounds of the formula III-3-1 and / or III-3-2

[0129] [ka]

[0130] In the formula, L 11 and L 12 has the same meaning as given in formula III, (O) represents O or a single bond, R IIIA is an alkyl or alkenyl group having up to 7 C atoms or a group Cy-C m H 2m+1 - represents m and n are the same or different and are 0, 1, 2, 3, 4, 5 or 6, preferably 1, 2 or 3, very preferably 1, Cy represents alkyl or alkenyl, each having up to 3 C atoms, or an alicyclic group having 3, 4 or 5 ring atoms, which may be substituted by halogen or CN, and preferably represents cyclopropyl, cyclobutyl or cyclopentyl.

[0131] The compounds of the formula III3-1 and / or III3-2 are contained in the LC medium alternatively or additionally, preferably additionally, to the compounds of the formula III.

[0132] Highly preferred compounds of formula III3-1 and III3-2 are:

[0133] [ka]

[0134] In the formula, alkoxy is a linear alkoxy group having 1 to 6 C atoms.

[0135] In another preferred embodiment of the invention the LC medium comprises one or more compounds of the formulae III-4 to III-6, preferably of the formula III-5.

[0136] [ka]

[0137] where the parameters have the meanings given above and R 11 preferably represents a linear alkyl, and R 12 preferably denotes alkoxy, each having 1 to 7 C atoms.

[0138] In another preferred embodiment the LC medium comprises one or more compounds of the formula I selected from the group of the compounds of the formulae III-7 to III-9, preferably of the formula III-8.

[0139] [ka]

[0140] where the parameters have the meanings given above and R 11 preferably represents a linear alkyl, and R 12 preferably denotes alkoxy, each having 1 to 7 C atoms.

[0141] In a preferred embodiment, the medium comprises one or more compounds of formula IV.

[0142] [ka]

[0143] During the ceremony, R 41 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, preferably an n-alkyl group, particularly preferably an n-alkyl group having 2, 3, 4 or 5 C atoms, R 42represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkoxy group having 1 to 6 C atoms (both preferably having 2 to 5 C atoms), an unsubstituted alkenyl group having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably a vinyl group or a 1-propenyl group, in particular a vinyl group.

[0144] The compound of formula IV is preferably selected from the group of compounds of formulae IV-1 to IV-4:

[0145] [ka]

[0146] During the ceremony, alkyl and alkyl' independently denote alkyl having 1 to 7 C atoms, preferably having 2 to 5 C atoms, alkenyl represents an alkenyl group having 2 to 5 C atoms, preferably 2 to 4 C atoms, particularly preferably 2 C atoms; alkenyl' represents an alkenyl group having 2 to 5 C atoms, preferably 2 to 4 C atoms, particularly preferably 2 to 3 C atoms, Alkoxy represents alkoxy having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0147] Preferably the LC medium comprises one or more compounds selected from the compounds of the formulae IV-1-1 to IV-1-4.

[0148] [ka]

[0149] Very preferably, the LC medium according to the invention comprises one or more compounds of the formulae IV-2-1 and / or IV-2-2.

[0150] [ka]

[0151] Very preferably, the LC medium according to the invention comprises a compound of the formula IV-3, in particular selected from the compounds of the formulae IV-3-1 to IV-3-4

[0152] [ka]

[0153] Very preferably, the LC medium according to the invention comprises a compound of the formula IV-4, in particular selected from the compounds of the formulae IV-4-1 and IV-4-2

[0154] [ka]

[0155] The LC medium preferably additionally comprises one or more compounds of the formula IVa.

[0156] [ka]

[0157] During the ceremony, R 41 and R 42 each independently represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy group having up to 12 C atoms, and [ka] Z 4 represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4-, -C4H8-, or -CF=CF-.

[0158] Preferred compounds of formula IVa are shown below.

[0159] [ka]

[0160] In the formula, alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms.

[0161] The LC media according to the invention preferably comprise at least one compound of the formula IVa-1 and / or IVa-2.

[0162] The proportion of compounds of formula IVa in the mixture as a whole is preferably at least 5% by weight.

[0163] Preferably the LC medium comprises one or more compounds of the formulae IVb-1 to IVb-3.

[0164] [ka]

[0165] During the ceremony, Alkyl and alkyl * each independently represent a linear alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 carbon atoms.

[0166] The proportion of biphenyls of the formulae IV-1 to IV-3 in the entire mixture is preferably at least 3% by weight, in particular 5% by weight or more.

[0167] Among the compounds of formulae IVb-1 to IVb-3, the compound of formula IVb-2 is particularly preferred.

[0168] Particularly preferred are biphenyls.

[0169] [ka]

[0170] In the formula, alkyl * represents an alkyl group having 1 to 6 C atoms, preferably n-propyl.

[0171] The LC media according to the invention particularly preferably comprise one or more compounds of the formulae IVb-1-1 and / or IVb-2-3.

[0172] In a particularly preferred embodiment the LC medium comprises one or more compounds of formula V

[0173] [ka]

[0174] During the ceremony, R 51 and R 52 are mutually independent R 41 and R 42 has one of the meanings given in the formula (I) and preferably denotes alkyl having 1 to 7 C atoms, preferably n-alkyl, particularly preferably n-alkyl having 1 to 5 C atoms, alkoxy having 1 to 7 C atoms, preferably n-alkoxy, particularly preferably n-alkoxy having 2 to 5 C atoms, alkoxyalkyl having 2 to 7 C atoms, preferably having 2 to 4 C atoms, alkenyl or alkenyloxy, preferably alkenyloxy, [ka] During the ceremony, [ka] Z 51 , Z 52 are each independently -CH-CH-, -CH-O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH-CH-, -CH-O- or a single bond, particularly preferably a single bond, n is 1 or 2.

[0175] The compound of formula V is preferably selected from the compounds of formulae V1 to V16.

[0176] [ka]

[0177] [ka]

[0178] In the formula, R 1 and R 2 is R above 2A R 1 and R 2 preferably each independently represent a straight-chain alkyl or alkenyl.

[0179] Preferred LC media comprise one or more compounds of the formula V-1, V-3, V-4, V-6, V-7, V-10, V-11, V-12, V-14, V-15 and / or V-16

[0180] The LC media according to the invention very particularly preferably comprise compounds of the formulae V-10, V-12, V-16 and / or IV-1, especially in amounts of 5 to 30%.

[0181] Preferred compounds of formula V-10 are shown below.

[0182] [ka]

[0183] The LC media according to the invention particularly preferably comprise tricyclic compounds of the formulae V-10a and / or V-10b in combination with one or more bicyclohexyl compounds of the formula IV-1. The total proportion of compounds of the formulae V-10a and / or V-10b in combination with one or more compounds selected from the bicyclohexyl compounds of the formula IV-1 is 5 to 40%, very particularly preferably 15 to 35%.

[0184] Very particularly preferred LC media comprise the compounds V-10a and IV-1-1.

[0185] [ka]

[0186] The compounds V-10a and IV-1-1 are preferably present in the mixture in a concentration of 15 to 35%, particularly preferably 15 to 25%, particularly preferably 18 to 22%, based on the mixture as a whole.

[0187] Very particularly preferred LC media comprise the compounds V-10b and IV-1-1.

[0188] [ka]

[0189] The compounds V-10b and IV-1-1 are preferably present in the mixture in a concentration of 15 to 35%, particularly preferably 15 to 25%, particularly preferably 18 to 22%, based on the mixture as a whole.

[0190] Very particularly preferred LC media comprise the following three classes of compounds:

[0191] [ka]

[0192] The compounds V-10a, V-10b and IV-1-1 are preferably present in the mixture in a concentration of 15 to 35%, particularly preferably 15 to 25%, particularly preferably 18 to 22%, based on the mixture as a whole.

[0193] Preferred LC media comprise at least one compound selected from the group of compounds below.

[0194] [ka]

[0195] In the formula, R 41 and R 42 and R 51 and R 52 has the meaning indicated above. Preferably, in compounds V-6, V-7 and IV-1, R 41 and R 51 represents alkyl or alkenyl having 1 to 6 or 2 to 6 C atoms, respectively, and R 42 and R 52 represents alkenyl having 2 to 6 C atoms.

[0196] Preferred LC media comprise at least one compound of the formulae V-6a, V-6b, V-7a, V-7b, IV-4-1, IV-4-2, IV-3a and IV-3b

[0197] [ka]

[0198] In the formula, alkyl represents an alkyl group having 1 to 6 C atoms, and alkenyl represents an alkenyl group having 2 to 6 C atoms.

[0199] The compounds of the formulae V-6a, V-6b, V-7a, V-7b, IV-4-1, IV-4-2, IV-3a and IV-3b are preferably present in the mixtures according to the invention in an amount of 1 to 40% by weight, preferably 5 to 35% by weight, very particularly preferably 10 to 30% by weight.

[0200] In a preferred embodiment of the invention, the LC medium additionally comprises one or more compounds of the formulae VI-1 to VI-9.

[0201] [ka]

[0202] [ka]

[0203] During the ceremony, R 7 are each independently a group represented by R in formula IIA. 2A has one of the meanings given in w and x each independently represent 1 to 6;

[0204] Particular preference is given to LC media which comprise at least one compound of the formula V-9.

[0205] In a preferred embodiment of the invention, the LC medium additionally comprises one or more compounds of the formulae VII-1 to VII-25.

[0206] [ka]

[0207] [ka]

[0208] [ka]

[0209] [ka]

[0210] During the ceremony, R represents a linear alkyl or alkoxy group having 1 to 6 C atoms, (O) represents -O- or a single bond, X represents F, Cl, OCF3 or OCHF2, L x represents H or F; m is 0, 1, 2, 3, 4, 5, or 6; and n is 1, 2, 3, or 4.

[0211] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentoxy.

[0212] X preferably represents F or OCH3, very preferably F.

[0213] The LC media according to the invention preferably contain terphenyls of the formulae VII-1 to VII-25 in an amount of 2 to 30% by weight, in particular 5 to 20% by weight.

[0214] Particularly preferred are compounds of formulae VII-1, VII-2, VII-4, VII-20, VII-21 and VII-22, in which X represents F. In these compounds, R preferably represents alkyl, furthermore alkoxy, each having 1 to 5 C atoms. In compounds of formula VII-20, R preferably represents alkyl or alkenyl, particularly alkyl. In compounds of formula VII-21, R preferably represents alkyl. In compounds of formulae VII-22 to VII-25, X preferably represents F.

[0215] Terphenyls are preferably employed in the LC media according to the invention if the mixture has a Δn value of 0.1 or more. Preferred LC media contain 2 to 20% by weight of one or more terphenyl compounds selected from the group of compounds VII-1 to VII-25.

[0216] Further preferred embodiments are listed below.

[0217] a) LC medium comprising at least one compound of the formulae Z-1 to Z-7.

[0218] [ka]

[0219] wherein R, (O) and alkyl have the meanings given above in Formula III.

[0220] b) Preferred LC media according to the invention comprise one or more substances which contain a tetrahydronaphthyl or naphthyl unit, such as, for example, compounds of the formulae N-1 to N-5.

[0221] [ka]

[0222] R in the formula 1N and R 2N are each independently R 2A and preferably represents straight-chain alkyl, straight-chain alkoxy or straight-chain alkenyl, Z 1 and Z 2 each independently represent -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CHCH2CH2-, -CH2CH2CH=CH-, -CHO-, -OCH2-, -COO-, -OCO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CF2O-, -OCF2-, -CH2- or a single bond.

[0223] c) Preferred LC media comprise one or more compounds selected from the group of the difluorodibenzochroman compounds of the formula BC, the chromans of the formula CR, the fluorinated phenanthrenes of the formulae PH-1 and PH-2.

[0224] [ka]

[0225] During the ceremony, R B1 , RB2 , R CR1 , R CR2 , R 1 , R 2 are each independently R 2A where c is 0, 1 or 2. R 1 and R 2 preferably independently of one another denote alkyl or alkoxy having 1 to 6 C atoms.

[0226] The LC media according to the invention preferably comprise compounds of the formulae BC, CR, PH-1, PH-2 in an amount of 3 to 20% by weight, in particular in an amount of 3 to 15% by weight.

[0227] Particularly preferred compounds of formulae BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5.

[0228] [ka]

[0229] [ka]

[0230] During the ceremony, Alkyl and alkyl * each independently represents a linear alkyl group having 1 to 6 carbon atoms, alkenyl and alkenyl * each independently represents a linear alkenyl group having 2 to 6 carbon atoms.

[0231] Very particular preference is given to LC media which comprise one, two or three compounds of the formulae BC-2, BF-1 and / or BF-2.

[0232] d) Preferred LC media comprise one or more indane compounds of the formula In

[0233] [ka]

[0234] During the ceremony, R 11 , R 12 , R 13 each independently represent a linear alkyl, alkoxy, alkoxyalkyl or alkenyl group having 1 to 6 C atoms, R 12 and R 13 represents an additional halogen, preferably F, [ka] represents i represents 0, 1 or 2.

[0235] Preferred compounds of formula In are compounds of formulae In-1 to In-16 shown below.

[0236] [ka]

[0237] [ka]

[0238] [ka]

[0239] Compounds of formulae In-1, In-2, In-3 and In-4 are particularly preferred.

[0240] The compounds of the formula In and the subformulae In-1 to In-16 are preferably employed in the LC media according to the invention in a concentration of 5% by weight or more, in particular 5 to 30% by weight, very particularly preferably 5 to 25% by weight.

[0241] e) Preferred LC media additionally comprise one or more compounds of the formulae L-1 to L-5.

[0242] [ka]

[0243] [ka]

[0244] During the ceremony, R and R 1 are each independently R in the above formula IIA. 2A where alkyl represents an alkyl group having 1 to 6 carbon atoms. The parameter s represents 1 or 2.

[0245] The compounds of the formulae L1 to L5 are preferably used in concentrations of 5 to 50% by weight, in particular 5 to 40% by weight, very particularly preferably 10 to 40% by weight.

[0246] f) Preferred LC media additionally comprise one or more compounds of the formulae IIA-Y.

[0247] [ka]

[0248] R in the formula 11 and R 12 is R in the above formula IIA 2A has one of the meanings given to L 1 and L 2 are the same or different and represent F or Cl.

[0249] Preferred compounds of formula IIA-Y are selected from the group consisting of the following subformulae:

[0250] [ka]

[0251] [ka]

[0252] In the formula, Alkyl and Alkyl * each independently represents a linear alkyl group having 1 to 6 C atoms, Alkoxy represents a linear alkoxy group having 1 to 6 C atoms, Alkenyl and Alkenyl * each independently represents a linear alkenyl group having 2 to 6 carbon atoms, and O represents an oxygen atom or a single bond. * preferably represents CH2=CH-, CH2=CHCH2CH2-, CH3-CH=CH-, CH3-CH2-CH=CH-, CH3-(CH2)2-CH=CH-, CH3-(CH2)3-CH=CH- or CH3-CH=CH-(CH2)2-.

[0253] Particularly preferred compounds of formula IIA-Y are selected from the group consisting of the following subformulae:

[0254] [ka]

[0255] In the formula, Alkoxy and Alkoxy * has the meaning defined above and preferably denotes methoxy, ethoxy, n-propyloxy, n-butyloxy or n-pentyloxy.

[0256] g) LC media additionally comprising one or more quaterphenyl compounds selected from the following formulae:

[0257] [ka]

[0258] During the ceremony, R Qis alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which groups may be fluorinated, X Q is F, Cl, a halogenated alkyl or alkoxy having 1 to 6 C atoms or a halogenated alkenyl or alkenyloxy having 2 to 6 C atoms, L Q1 ~L Q6 are each independently H or F, with the proviso that L Q1 ~L Q6 At least one of is F.

[0259] Preferred compounds of formula Q are Q is linear alkyl having 2 to 6 C atoms, very preferably ethyl, n-propyl or n-butyl.

[0260] Preferred compounds of formula Q are Q3 and L Q4 is F.

[0261] Further preferred compounds of formula Q are Q3 , L Q4 and L Q1 and L Q2 One or two of these are F.

[0262] Preferred compounds of formula Q are X Q represents F or OCF3, very preferably F.

[0263] The compounds of formula Q are preferably selected from the following sub-formulae:

[0264] [ka]

[0265] In the formula, R Qhas one of the meanings of formula Q or one of the preferred meanings given above and below, and is preferably ethyl, n-propyl or n-butyl.

[0266] Especially R Q Particularly preferred are compounds of formula Q1 wherein is n-propyl.

[0267] Preferably the proportion of compounds of formula Q in the LC host mixture is greater than 0 to 5% by weight, very preferably 0.05 to 2% by weight, more preferably 0.1 to 1% by weight, most preferably 0.1 to 0.8% by weight.

[0268] Preferably the LC medium comprises 1 to 5, preferably 1 or 2, compounds of formula Q.

[0269] The addition of quaterphenyl compounds of formula Q to the LC host mixture can reduce ODF unevenness while maintaining high UV absorption, enabling fast and complete polymerization, strong and fast tilt angle generation, and enhancing the UV stability of the LC medium.

[0270] In addition, the compound of formula Q with positive dielectric anisotropy can be added to an LC medium with negative dielectric anisotropy to increase the dielectric constant ε ∥ and ε ⊥ In particular, the dielectric constant ε can be controlled by keeping the dielectric anisotropy Δε constant. ∥ It is possible to achieve high values ​​of ρ, thereby reducing kickback voltage and image sticking.

[0271] The LC media according to the invention preferably have

[0272] one or more compounds of the formula IA or sub-formulas thereof, preferably of the formula IA1 or IA2, preferably in a concentration in the range of 2 to 20%, very preferably 3 to 14% by weight, most preferably 4 to 10%;

[0273] one or more compounds of the formula IB or a sub-formula thereof, preferably of the formula IB1 or IB2, preferably in a concentration in the range of 0.5-5%, very preferably 0.5-2%;

[0274] and / or one or more compounds of formula IIA and IIB, preferably in a total concentration ranging from 30% to 45%;

[0275] and / or one or more compounds of formula IV, preferably in a total concentration ranging from 35 to 60%, more preferably from 40 to 55%, particularly preferably from 45 to 50%;

[0276] and / or one or more compounds of the formulae IIA and IIB and III-2, preferably in a total concentration ranging from 30 to 65%, more preferably from 35% to 60%, particularly preferably from 40% to 55% Includes.

[0277] In particular, the media

[0278] one or more compounds CY-n-Om, in particular CY-3-O4, CY-5-O4 and / or CY-3-O2, preferably in a total concentration in the range of 5% to 30%, preferably 10% to 20%;

[0279] one or more compounds PY-n-Om, in particular PY-1-O2, PY-2-O2 and / or PY-3-O2, preferably in a total concentration in the range of 5% to 40%, preferably 10% to 30%;

[0280] and / or CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and / or CPY-5-O2, preferably in a concentration of more than 5%, in particular 7% to 20%, based on the total mixture;

[0281] and / or one or more compounds CCY-n-Om, preferably CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and / or CCY-5-O2, preferably in a concentration of more than 3%, in particular 5-15%, based on the total mixture;

[0282] and / or CPY-n-Om and CY-n-Om, preferably at a concentration of 10-80% based on the total mixture;

[0283] and / or CPY-n-Om and PY-n-Om, preferably CPY-2-O2 and / or CPY-3-O2 and PY-3-O2 or PY-1-O2, preferably in a concentration of 5 to 20%, more preferably 10 to 15%, based on the total mixture,

[0284] and / or Compounds CC-3-V1 and / or CC-4-V1 (one or more) in a total concentration ranging from 5 to 40%, more preferably from 15 to 35%, particularly preferably from 20 to 30%,

[0285] and / or one or more compounds of the formula B-nO-Om and / or B(S)-nO-Om, in particular the compound B(S)-2O-O5, preferably in a concentration ranging from 2 to 10%, and the compound CC-3-V1, in a total concentration ranging from 10 to 30%, preferably from 15 to 20%,

[0286] and / or 0.1% to 3% of the compound PPGU-3-F Includes.

[0287] The liquid crystal media according to the invention advantageously have a nematic phase preferably at temperatures from -20°C to 70°C, particularly preferably from -30°C to 80°C, very particularly preferably from -40°C to 90°C.

[0288] The medium according to the invention has a clearing temperature of 70°C or higher, preferably 74°C or higher.

[0289] The expression "having a nematic phase" in this specification means, on the one hand, that neither a smectic phase nor crystallization is observed at the corresponding low temperature, and, on the other hand, that clearing does not occur upon heating from the nematic phase. Low-temperature studies are carried out in a flow viscometer at the corresponding temperature and confirmed by storage for at least 100 hours in test cells with a layer thickness corresponding to the electro-optical application. A medium is considered stable at this temperature if the storage stability of the corresponding test cell at a temperature of -20°C is 1000 hours or more. At temperatures of -30°C and -40°C, the corresponding times are 500 hours and 250 hours, respectively. At higher temperatures, the clearing point is measured in a capillary tube by conventional methods.

[0290] The liquid crystal mixture preferably has a nematic phase range of at least 60 K and a maximum of 30 mm 2 ·s -1 Flow viscosity ν 20 It has.

[0291] The mixture is nematic at temperatures below -20°C, preferably below -30°C, and very preferably below -40°C.

[0292] The birefringence value Δn of the liquid crystal mixture is generally between 0.07 and 0.16, preferably between 0.08 and 0.15, very preferably between 0.09 and 0.14.

[0293] In a preferred embodiment of the present invention, the medium has a birefringence in the range of 0.090 to 0.110, preferably 0.095 to 0.108, especially 0.102 to 0.107.

[0294] In another preferred embodiment, the medium according to the present invention has a birefringence of 0.120 or more, preferably in the range of 0.125 to 0.145, more preferably 0.130 to 0.140.

[0295] The liquid crystal mixture according to the invention has a dielectric anisotropy Δε of −1.5 to −8.0, preferably of −2.0 to −4.0, in particular of −2.5 to −3.6.

[0296] The rotational viscosity γ1 at 20° C. is preferably 120 mPa·s or less, particularly preferably 105 mPa·s or less.

[0297] In a preferred embodiment, the rotational viscosity γ1 at 20° C. is 100 mPa·s or less, particularly 95 mPa·s or less.

[0298] The liquid-crystalline media according to the invention have relatively low values ​​of the threshold voltage (V0): they are preferably in the range from 1.7 V to 3.0 V, particularly preferably ≦2.7 V, very particularly preferably ≦2.5 V.

[0299] For the present invention, the term "threshold voltage" relates to the capacitive threshold (V0), also called the Freederickss threshold, unless otherwise specified.

[0300] In addition, the liquid-crystalline media according to the invention have high values ​​for the voltage holding ratio in liquid-crystal cells.

[0301] In general, liquid crystal media with a low addressing voltage or threshold voltage show a lower voltage holding ratio than those with a high addressing voltage or threshold voltage, and vice versa.

[0302] In the present invention, the term "dielectrically positive compound" refers to a compound with Δε > 1.5, the term "dielectrically neutral compound" refers to one with -1.5 ≦ Δε ≦ 1.5, and the term "dielectrically negative compound" refers to one with Δε < -1.5. The dielectric anisotropy of a compound is determined herein by dissolving 10% of the compound in a liquid crystal host and measuring the capacitance of the resulting mixture in at least one test cell with a layer thickness of 20 μm in each case and with homeotropic and homogeneous surface alignment at 1 kHz. The measurement voltage is typically between 0.5 V and 1.0 V, but is always below the capacitance threshold of each liquid crystal mixture under consideration.

[0303] All temperature values ​​given for this invention are in °C.

[0304] The LC media according to the invention are suitable for all VA-TFT (vertical alignment-thin film transistor) applications, such as, for example, VAN (vertically aligned nematic), MVA (multidomain VA), (S)-PVA (super patterned VA), ASV (advanced super view or axially symmetric VA), PSA (polymer sustained VA) and PS-VA (polymer stabilized VA). They are furthermore suitable for IPS (in-plane switching) and FFS (fringe field switching) applications with negative Δε.

[0305] The nematic LC medium in the displays according to the invention generally comprises two components A and B which themselves consist of one or more individual compounds.

[0306] Component A has a significantly negative dielectric anisotropy, giving the nematic phase a dielectric anisotropy of -0.5 or less, and preferably comprises, in addition to one or more compounds of formulae IA and IB, compounds of formulae IIA, IIB and / or IIC, and also one or more compounds of formula IV-1.

[0307] The proportion of component A is preferably between 45 and 100%, in particular between 60 and 85%.

[0308] For component A, one (or more) individual compounds are preferably selected that have a Δε value of less than or equal to −0.8, this value having to be more negative the smaller the proportion of component A in the overall mixture.

[0309] Component B has pronounced nematogenicity and 30 mm 2 ·s -1 Less than 25mm, preferably 2 ·s -1 It has the following flow viscosity:

[0310] Many suitable materials are known to those skilled in the art from the literature. Compounds of formula O-17 are particularly preferred.

[0311] Particularly preferred individual compounds in component B have a viscosity of 18 mmHg at 20°C. 2 ·s -1 Less than 12mm, preferably 2 ·s -1 It is a very low viscosity nematic liquid crystal having the following flow viscosity:

[0312] Component B is unidirectionally or enantiomerically nematic, does not have a smectic phase, and can prevent the occurrence of smectic phases in LC media down to very low temperatures. For example, when various highly nematogenic materials are added to a smectic liquid crystal mixture, the nematogenicity of these materials can be compared through the degree of smectic phase suppression achieved.

[0313] The mixture may also contain a component C which comprises compounds having a dielectric anisotropy of Δε≧1.5. These so-called positive compounds are generally present in mixtures of negative dielectric anisotropy in amounts of up to 20% by weight, based on the entire mixture.

[0314] In addition to one or more compounds of the formulae IA and IB, the medium preferably comprises 4 to 15, in particular 5 to 12, particularly preferably less than 10, compounds of the formulae IIA, IIB and / or IIC, and optionally one or more compounds of the formula IV-1.

[0315] In addition to the compounds of formulae IA and IB and formulae IIA, IIB and / or IIC and optionally IV-1, other components may also be present, for example in amounts of up to 45%, preferably up to 35%, in particular up to 10% of the total mixture.

[0316] The other components are preferably selected from nematic or nematogenic substances, in particular known substances, from the classes of azoxybenzene, benzylideneaniline, biphenyl, terphenyl, phenyl or cyclohexylbenzoate, phenyl or cyclohexylcyclohexanecarboxylate, phenylcyclohexane, cyclohexylbiphenyl, cyclohexylcyclohexane, cyclohexylnaphthalene, 1,4-biscyclohexylbiphenyl or cyclohexylpyrimidine, phenyl or cyclohexyldioxane, optionally halogenated stilbenes, benzyl phenyl ethers, tolanes and substituted cinnamic acid esters.

[0317] The most important compounds suitable as components of this type of liquid crystal phase can be characterized by formula IV.

[0318] [ka]

[0319] wherein L and E each represent a carbocyclic or heterocyclic ring system from the group formed by 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted pyrimidine and 1,3-dioxane rings, 2,6-disubstituted naphthalene, di- and tetrahydronaphthalene, quinazoline and tetrahydroquinazoline, G is -CH=CH-, -N(O)=N-, -CH=CQ-, -CH=N(O)-, -C≡C-, -CH2-CH2-, -CO-O-, -CH2-O-, -CO-S-, -C Represents H2-S-, -CH=N-, -COO-Phe-COO-, -CF2O-, -CF=CF-, -OCF2-, -OCH2-, -(CH2)4-, -(CH2)3O-, or a CC single bond, Q represents a halogen, preferably chlorine, or represents -CN, and R 20 and R 21represents alkyl, alkenyl, alkoxy, alkoxyalkyl or alkoxycarbonyloxy, each having up to 18, preferably up to 8, carbon atoms, or one of these groups represents CN, NC, NO, NCS, CF, SF, OCF, F, Cl or Br.

[0320] In most of these compounds, R 20 and R 21 are different from each other, and one of these groups is usually an alkyl or alkoxy group. Other variations of the proposed substituents are also common. Many such substances or mixtures thereof are commercially available. All of these substances can be prepared by methods known from the literature.

[0321] It will be clear to those skilled in the art that the VA, IPS or FFS mixtures according to the invention may also comprise compounds in which, for example, H, N, O, Cl and F are replaced by the corresponding isotopes.

[0322] The LC medium preferably has a nematic LC phase.

[0323] Preferably the LC medium comprises one or more polymerisable compounds selected of formula M

[0324] [ka]

[0325] In the formula, the individual radicals, which are identical or different at each occurrence, each have the following meaning independently of one another: R a and R b is P, P-Sp-, H, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, SF5 or a linear or branched alkyl having 1 to 25 C atoms, provided that in addition one or more non-adjacent CH2 groups are each independently -C(R) such that the O and / or S atoms are not directly linked to each other; 0 )=C(R00 )-, -C≡C-, -N(R 00 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, provided that in addition one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, provided that B 1 and / or B. 2 contains saturated C atoms, and R a and / or R b may also represent a group that can be linked to this saturated C atom via a spiro bond, However, the group R a and R b at least one of which represents or contains the group P or P-Sp-, P is a polymerizable group, Sp is a spacer group or a single bond; B 1 and B 2 is preferably an aromatic, heteroaromatic, alicyclic or heterocyclic group having 4 to 25 ring atoms, which may also contain fused rings, and which may be mono- or polysubstituted by L; Z b is -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, CR 0 R 00 or a single bond, R 0 and R 00 are each independently H or alkyl having 1 to 12 C atoms, m represents 0, 1, 2, 3 or 4; n1 represents 1, 2, 3 or 4; L is P, P-Sp-, OH, CH2OH, 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, optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or linear or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, with the proviso that one or more H atoms may additionally be replaced by F, Cl, P or P-Sp-, P and Sp have the meanings indicated above, Y 1 represents a halogen, R x is P, P-Sp-, H, halogen, linear, branched or cyclic alkyl having 1 to 25 C atoms (provided that in addition, one or more non-adjacent CH groups may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, and in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-), an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

[0326] Preferred compounds of formula M are B 1 and B 2In each case, independently of one another, 1,4-phenylene, naphthalene-1,4-diyl, naphthalene-2,6-diyl, phenanthrene-2,7-diyl, anthracene-2,7-diyl, fluorene-2,7-diyl, coumarin, flavone (in addition, one or more CH groups in these groups may be replaced by N), cyclohexane-1,4-diyl (in addition, one or more non-adjacent CH groups may be replaced by O and / or S), 1,4-cyclohexenylene, bicyclo[1 and is selected from the group consisting of: bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, piperidine-1,4-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, indan-2,5-diyl or octahydro-4,7-methanoindan-2,5-diyl, all of which groups may be unsubstituted or mono- or polysubstituted by L as defined above.

[0327] Particularly preferred compounds of formula M are B 1 and B 2 in each case independently of one another denote 1,4-phenylene, 1,3-phenylene, naphthalene-1,4-diyl or naphthalene-2,6-diyl.

[0328] Highly preferred compounds of formula M are selected from the following formulae:

[0329] [ka]

[0330] [ka]

[0331] [ka]

[0332] [ka]

[0333] [ka]

[0334] [ka]

[0335] In the formulae, the individual radicals, which are identical or different at each occurrence, each have the following meanings independently of one another: P 1 , P 2 , P 3 is a polymerizable group, preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy; Sp 1 , Sp 2 , Sp 3 is a single bond or a spacer group, provided that in addition thereto one or more groups P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 - is R aa may represent, provided that any group P 1 -Sp 1 -, P 2 -Sp 2 - and P 3 -Sp 3 -At least one of the characters is R aa preferably -(CH2) p1 -, -(CH2) p1 -O-, -(CH2) p1 -CO-O- or -(CH2) p1 -O-CO-O-, wherein p1 is an integer of 1 to 12; R aais H, F, Cl, CN or a linear or branched alkyl having 1 to 25 C atoms (provided that in addition one or more non-adjacent CH groups may be present, in each case independently of one another, such that O and / or S atoms are not directly linked to one another) -C(R 0 )=C(R 00 )-, -C≡C-, -N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, provided that in addition one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 -), particularly preferably linear or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyl or alkylcarbonyloxy having 1 to 12 C atoms, with the proviso that alkenyl and alkynyl groups have at least 2 C atoms and branched groups have at least 3 C atoms, with the proviso that R aa is a base P 1 , P 2 or P 3 does not imply or include R 0 , R 00 is H or alkyl having 1 to 12 C atoms, R y and R z is H, F, CH3 or CF3, X 1 , X 2 , X 3 is -CO-O-, -O-CO- or a single bond, Z M1 -O-, -CO-, -C(R y R z )- or -CF2CF2-, Z M2 , Z M3 is -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or -(CH2) n where n is 2, 3 or 4; L is F, Cl, CN, or a linear or branched alkyl, alkoxy, thioalkyl, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy, or alkoxycarbonyloxy having 1 to 12 carbon atoms, which may be monofluorinated or polyfluorinated; L', L" are H, F or Cl; k is 0 or 1, r is 0, 1, 2, 3 or 4; s is 0, 1, 2 or 3; t is 0, 1, or 2; x is 0 or 1.

[0336] Compounds of formula M2, M13 and M33, in particular those containing only two polymerizable groups P 1 and P 2 Highly preferred are bireactive compounds comprising:

[0337] Compounds selected from the formulae M17 to M32, in particular from the formulae M20, M22, M24, M27, M30 and M32, in particular compounds having only three polymerizable groups P 1 , P 2 and P 3 Further preferred are trireactive compounds comprising:

[0338] In the compounds of formulae M1 to M33, [ka]

[0339] in which L, identically or differently, has one of the meanings given above and below in each occurrence, preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, CH=CH2, C(CH3)=CH2, SCH3, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, CH=CH2, C(CH3)=CH2, SCH3, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, CH=CH2, C(CH3)=CH2, SCH3, OCH3, COCH3 or OCF 3、 Most preferred is F, SCH3 or OCH3.

[0340] Preferred compounds of formulae M1 to M33 are P 1 , P 2 and P 3 represents an acrylate, methacrylate, oxetane or epoxy group, very preferably an acrylate or methacrylate group, most preferably a methacrylate group.

[0341] Further preferred compounds of formulae M1 to M33 are Sp 1 , Sp 2 and Sp 3 is a single bond.

[0342] Further preferred compounds of formulae M1 to M33 are Sp 1 , Sp 2 and Sp 3 represents a single bond, and Sp 1 , Sp 2 and Sp 3 The other one is different from a single bond.

[0343] Further preferred compounds of the formulae M1 to M33 are those which contain a group Sp different from a single bond 1 , Sp 2 and Sp 3 Ga-(CH2) s1represents -X"-, where s1 is an integer of 1 to 6, preferably 2, 3, 4, or 5, and X" is a bond to the adjacent benzene ring and is -O-, -O-CO-, -CO-O-, -O-CO-O-, or a single bond.

[0344] Further preferred compounds of formula M are selected from Table D, in particular selected from the group consisting of formulae RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-92, RM-102, RM-103, RM-109, RM-116, RM-117, RM-120, RM-121, RM-122, RM-139, RM-142, RM-153, RM-155, RM-158, RM-159, RM-162, RM-163, and RM-164 through RM-176.

[0345] Particular preference is given to LC media which comprise one, two or three polymerisable compounds of the formula M.

[0346] Further preference is given to LC media comprising two or more direactive polymerisable compounds of formula M, preferably selected from formulae M1 to M16 and M33, very preferably selected from formulae M2, M13 and M33.

[0347] Further preference is given to an LC medium comprising one or more direactive polymerisable compounds of formula M, preferably selected from the formulae M1 to M16 and M33, very preferably from the formulae M2, M13 and M33, and one or more trireactive polymerisable compounds of formula M, preferably selected from the formulae M17 to M32, very preferably from the formulae M20, M22, M24, M27, M30 and M32.

[0348] Further preferred are LC media comprising one or more polymerizable compounds of formula M, very preferably selected from the formulae M2, M13, M22, M24, M27, M30, M32 and M33, in which at least one r is not 0 or at least one of s and t is not 0, and in which L is selected from the preferred groups indicated above, most preferably from F, OCH3 and SCH3.

[0349] Further preference is given to LC media comprising one or more polymerisable compounds which are preferably selected from formula M, very preferably from formulae M1 to M33 and which exhibit absorption in the wavelength range from 320 to 380 nm.

[0350] Further preferred are LC media comprising one or more polymerizable compounds selected from Table D. 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-64, RM-74, RM-76, RM-88, RM-102, RM-103, RM-109, RM-117, RM-120, RM-121, RM-122, and RM-145 to RM-152, RM-162, RM-163, and RM-164 to RM-176 are particularly preferred.

[0351] Further preferred compounds of formulae M1 to M33 are those selected from Table D below, in particular those selected from the group consisting of formulae RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-92, 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-150, RM-152, RM-153, RM155 and RM-156, RM-162, RM-163 and RM-164 to RM-176.

[0352] Particular preference is given to LC media comprising one, two or three polymerisable compounds of the formula M or selected from the formulae M1 to M33.

[0353] The combination of the compounds of the preferred embodiments described above with the polymeric compounds described above and below results in a consistently high clearing point and high HR value, as well as a low threshold voltage, a low rotational viscosity and very good low-temperature stability in the LC media according to the invention, making it possible to rapidly establish particularly low tilt angles (i.e. large tilts) in PSA displays. In particular, the LC media also show significantly reduced response times, especially gray-scale response times, in PSA displays compared to LC media according to the prior art.

[0354] For use in PSA displays, the total proportion of polymerizable compounds such as those of formulae M or M1 to M33 in the LC medium is preferably 0.01 to 2.0%, very preferably 0.1 to 1.0%, most preferably 0.2 to 0.8%.

[0355] For use in SA-VA displays, the total proportion of polymerizable compounds such as those of formulae M or M1 to M33 in the LC medium is preferably from >0 to <3%, very preferably from >0 to <2%, more preferably from 0.05 to 2.0%, most preferably from 0.05 to 1.0%.

[0356] Compounds of formula M and its subformulas are known to those skilled in the art and can be prepared analogously to processes described in standard textbooks of organic chemistry such as, for example, Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart.

[0357] For example, acrylic or methacrylic esters can be prepared by esterifying the corresponding alcohol with an acid derivative, such as (meth)acryloyl chloride or (meth)acrylic anhydride, in the presence of a base, such as pyridine, triethylamine, or 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively, esters can be prepared by esterifying alcohols with (meth)acrylic acid in the presence of a dehydrating reagent, for example, according to Steglich, using dicyclohexylcarbodiimide (DCC), N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC), or N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and DMAP.

[0358] The invention further relates to an LC medium or an LC display as described above, in which the polymerizable compounds such as of formula M and its sub-formulas are present in polymerized form.

[0359] One or more initiators may be added to the LC medium. Suitable conditions for polymerization, as well as suitable types and amounts of initiators, are known to those skilled in the art and are described in the literature. For example, commercially available photoinitiators Irgacure 651®, Irgacure 184®, Irgacure 907®, Irgacure 369®, or Darocure 1173® (Ciba) are suitable for free-radical polymerization. If an initiator is used, its proportion in the overall mixture is preferably 0.001 to 5% by weight, particularly preferably 0.001 to 1% by weight.

[0360] The polymerizable compound according to the present invention is also suitable for polymerization without initiator, which has considerable advantages, such as lower material cost, especially the reduction of the contamination of LC medium due to the possible residual amount of initiator or its decomposition product.In this way, polymerization can be carried out without adding initiator.Therefore, in a preferred embodiment, LC medium does not contain polymerization initiator.

[0361] The polymerizable component of the cholesteric liquid crystal medium may also contain one or more stabilizers, for example to prevent undesired spontaneous polymerization of the RM during storage or transportation. Suitable types and amounts of stabilizers are known to those skilled in the art and are described in the literature. Commercially available stabilizers, such as those of the Irganox® series (Ciba), are particularly suitable, such as Irganox® 1076. When a stabilizer is used, its proportion, based on the RM or polymerizable component (component A), is preferably 10 to 50,000 ppm, particularly preferably 50 to 5,000 ppm.

[0362] In a preferred embodiment the LC medium comprises one or more chiral dopants, preferably in a concentration of 0.01 to 1% by weight, very preferably 0.05 to 0.5% by weight, which chiral dopants are preferably selected from the group consisting of the compounds from Table B below, very preferably from the group consisting of R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011 and R- or S-5011.

[0363] In another preferred embodiment the LC medium comprises a racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the previous paragraph.

[0364] In another preferred embodiment of the invention the LC medium comprises one or more further stabilizers, preferably selected from the group consisting of the following formulae:

[0365] [ka]

[0366] In the formula, the individual radicals each independently of one another have the following meanings, which may be the same or different at each occurrence: R a~d is linear or branched alkyl having 1 to 10, preferably 1 to 6, very preferably 1 to 4 C atoms, most preferably methyl, X S is H, CH3, OH or O ● and A S is an optionally substituted linear, branched or cyclic alkylene having 1 to 20 C atoms, n is an integer of 1 to 6, preferably 3.

[0367] Preferred stabilizers of formula S3 are selected from formula S3A:

[0368] [ka]

[0369] In the formula, n2 is an integer from 1 to 12, provided that the group (CH2) n2 One or more H atoms in may optionally be replaced by methyl, ethyl, propyl, butyl, pentyl or hexyl.

[0370] Highly preferred stabilizers are selected from the group consisting of the following formulae:

[0371] [ka]

[0372] [ka]

[0373] [ka]

[0374] [ka]

[0375] In a preferred embodiment the liquid crystal medium comprises one or more stabilizers selected from the group consisting of the formulae S1-1, S2-1, S3-1, S3-1 and S3-3.

[0376] In a preferred embodiment the liquid crystalline medium comprises one or more stabilizers selected from Table C below.

[0377] The proportion of stabilizers such as those of the formulae S1 to S3 in the liquid-crystalline medium is preferably between 10 and 500 ppm, very preferably between 20 and 100 ppm.

[0378] In another preferred embodiment the LC medium according to the invention comprises a self-aligning (SA) additive, preferably in a concentration of 0.1 to 2.5%.

[0379] In another preferred embodiment the LC medium according to the invention comprises a self-aligning (SA) additive, preferably in a concentration of 0.1 to 2.5%.

[0380] In a preferred embodiment, the SA-VA display according to the present invention does not include a polyimide alignment layer.In another preferred embodiment, the SA-VA display according to the preferred embodiment includes a polyimide alignment layer.

[0381] Preferred SA additives for use in this preferred embodiment are selected from compounds comprising a mesogenic group and a linear or branched alkyl side chain terminated with one or more polar anchor groups selected from hydroxy, carboxy, amino or thiol groups.

[0382] Further preferred SA additives comprise one or more polymerizable groups linked to a mesogenic group, optionally via a spacer group. These polymerizable SA additives can be polymerized in the LC medium under conditions similar to those applied to the RM in the PSA process.

[0383] Suitable SA additives for inducing homeotropic alignment, particularly for use in SA-VA mode displays, are disclosed, for example, in US Patent Application Publication Nos. 2013 / 0182202, 2014 / 0838581, 2015 / 0166890 and 2015 / 0252265.

[0384] In another preferred embodiment the LC medium or polymer stabilized SA-VA display according to the invention comprises one or more self-aligning additives selected from Table E below.

[0385] In another preferred embodiment the LC medium according to the invention comprises one or more SA additives, preferably selected from Table E, in a concentration of 0.1 to 5%, very preferably 0.2 to 3%, most preferably 0.2 to 1.5%.

[0386] The present invention further relates to an LC display comprising an LC medium according to the invention as described above and below, preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0387] The present invention further relates to an LC display comprising an LC medium as described above and below, in which the polymerizable compound is present in polymerized form, preferably a PSA or SA display, very preferably a PS-VA, PS-IPS, PS-FFS or SA-VA display.

[0388] For the production of PSA or polymer stabilized SA displays, the polymerizable compound contained in the LC medium is preferably polymerized by in situ polymerization in the LC medium between the substrates of the LC display while applying a voltage to the electrodes.

[0389] The structure of the display according to the invention corresponds to the usual geometry of a PSA display, as described in the prior art cited at the outset. A geometry without protrusions is preferred, in particular a geometry in which, in addition, the electrode on the color filter side is unstructured and only the electrode on the TFT side has slots. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US Patent Application Publication No. 2006 / 0066793.

[0390] A preferred PSA type liquid crystal display of the present invention is: a first substrate including pixel electrodes defining pixel areas, the pixel electrodes being connected to switch elements disposed in each pixel area, optionally including a micro-slit pattern; and optionally a first alignment layer disposed on the pixel electrodes; a second substrate including a common electrode layer, optionally disposed over the portion of the second substrate facing the first substrate, and optionally a second alignment layer; an LC layer disposed between a first substrate and a second substrate and comprising an LC medium as described above and below, wherein the polymerizable compound may be present in polymerized form; Includes.

[0391] The first and / or second alignment layers control the alignment direction of the LC molecules in the LC layer. For example, in a PS-VA display, the alignment layers are selected to impart homeotropic (or vertical) alignment (i.e., perpendicular to the surface) or tilted alignment to the LC molecules. Such alignment layers may comprise, for example, polyimide and may be rubbed or prepared by photoalignment methods.

[0392] The LC layer comprising the LC medium can be deposited between the substrates of the display by methods conventionally used by display manufacturers, such as the so-called one-drop-filling (ODF) method. The polymerizable components of the LC medium are then polymerized, for example by UV photopolymerization. Polymerization can be carried out in one step or in two or more steps.

[0393] PSA displays may include additional elements such as color filters, black matrices, passivation layers, optical retardation layers, transistor elements for addressing individual pixels, all of which are well known to those skilled in the art and can be employed without inventive skill.

[0394] The electrode structure can be designed by those skilled in the art depending on the type of display. For example, in the case of a PS-VA display, multi-domain alignment of LC molecules can be induced by providing electrodes with slits and / or bumps or protrusions to create two or more different tilt alignment directions.

[0395] Upon polymerization, the polymerizable compound forms a copolymer, which causes the LC molecules in the LC medium to have a certain tilt angle. Without wishing to be bound by any particular theory, it is believed that at least a portion of the cross-linked polymer formed by the polymerizable compound phase-separates or precipitates from the LC medium to form a polymer layer on the substrate or electrode, or on an alignment layer disposed thereon. Microscopy data (e.g., SEM and AFM) confirm that at least a portion of the formed polymer accumulates at the LC / substrate interface.

[0396] The polymerization can be carried out in one step, optionally with the application of a voltage, to generate the tilt angle, followed by a second polymerization step in which the unreacted compounds from the first step are polymerized or crosslinked ("final cure") without the application of a voltage.

[0397] Suitable and preferred methods of polymerization are, for example, thermal or photopolymerization, preferably photopolymerization, especially UV-induced photopolymerization, which can be achieved by exposing the polymerizable compound to UV radiation.

[0398] The polymerizable compounds of formula M and its sub-formulas exhibit good UV absorption and are therefore particularly suitable in the preparation process of PSA displays, in particular comprising one or more of the following features or any combination thereof:

[0399] The polymerizable medium is exposed to UV light within the display, including a two-step process in which a first UV exposure step with applied voltage ("UV1 step") generates a tilt angle, and a second UV exposure step without applied voltage ("UV2 step") completely polymerizes the polymerizable medium;

[0400] The polymerizable medium is exposed to UV light, preferably in at least the UV2 step, more preferably in both the UV1 and UV2 steps, in displays produced by UV-LED lamps;

[0401] The polymerizable medium is exposed to UV light in the display, generated by energy-saving UV lamps (also known as "green UV lamps"). These lamps are characterized by a relatively low intensity (1 / 100 to 1 / 10 of conventional UV1 lamps) in the absorption spectrum of 300 to 380 nm, and are preferably used in the UV2 process, but can also be used in the UV1 process if high intensity needs to be avoided.

[0402] The polymerizable medium is exposed to UV light in the display produced by a UV lamp with an emission spectrum shifted to longer wavelengths, preferably above 340 nm, more preferably below 350-370 nm, and very preferably 355-368 nm, to avoid short UV light exposure in the PS-VA process.

[0403] The UV shift to lower intensity and longer wavelengths protects the organic layers from damage that can be caused by UV light.

[0404] A preferred embodiment of the present invention relates to a method for preparing a PSA display as described above and below, comprising one or more of the following features or any desired combination thereof: Irradiating the polymerizable LC medium with UV light in two steps, including a first UV exposure step ("UV-1 step") in which a voltage is applied to generate a tilt angle, and a second UV exposure step ("UV-2 step") in which no voltage is applied to complete the polymerization, The polymerizable LC medium is preferably exposed to UV2 and optionally UV1 in the wavelength range of 300-380 nm at 0.5 mW / cm 2 ~10mW / cm 2 and irradiating the sample with UV light generated by a UV lamp having an intensity of irradiating the polymerizable LC medium with UV light having a wavelength of greater than or equal to 340 nm, preferably less than or equal to 420 nm, very preferably in the range from 340 to 380 nm, more preferably in the range from 350 to less than 370 nm, most preferably in the range from 355 to 368 nm, The polymerizable LC medium is irradiated with UV light while a voltage is applied to the electrodes of the display. -UV light is irradiated using a UV-LED lamp.

[0405] This preferred method can be carried out, for example, by using a desired UV lamp or a bandpass filter and / or cutoff filter that substantially transmits UV light having the desired wavelength and substantially blocks light having undesired wavelengths. For example, if irradiation with UV light having a wavelength λ of 300 to 400 nm is desired, UV irradiation can be carried out using a wide bandpass filter that substantially transmits wavelengths λ greater than 300 nm and less than 400 nm. If irradiation with UV light having a wavelength λ greater than 340 nm is desired, UV irradiation can be carried out using a cutoff filter that substantially transmits wavelengths λ greater than 340 nm.

[0406] Preferably, the UV irradiation is carried out using a UV-LED lamp.

[0407] The use of UV-LED lamps with only one narrow emission peak in the PSA process offers several advantages, such as more efficient light energy transfer to the polymerizable compound in the LC medium, depending on the selection of an appropriate polymerizable compound that absorbs at the emission wavelength of the LED lamp. This allows for a reduction in UV intensity and / or UV exposure time, thereby shortening cycle time and saving energy and manufacturing costs. Another advantage is that the narrow emission spectrum of the lamp makes it easier to select a wavelength suitable for photopolymerization.

[0408] Highly preferably, the UV light source is a UV-LED lamp emitting a wavelength in the range of 340 to 400 nm, more preferably in the range of 340 to 380 nm. A UV-LED lamp emitting UV light with a wavelength of 365 nm is especially preferred.

[0409] This preferred method allows for the manufacture of displays using longer wavelength UV, thereby reducing or avoiding the harmful and damaging effects of the short wavelength component of UV light.

[0410] The UV radiation energy is generally 6 to 100 J, depending on the conditions of the manufacturing process.

[0411] The LC media according to the present invention may additionally comprise one or more further components or additives, which are preferably selected, but not limited to, from the following list: comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, hydrophobizing agents, adhesives, flow improvers, antifoaming agents, degassing agents, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0412] Furthermore, the LC medium can contain, for example, 0 to 15% by weight of pleochroic dyes, nanoparticles, conductive salts, preferably ethyl dimethyldodecylammonium 4-hexoxybenzoate, tetrabutylammonium tetraphenylborate, or crown ether complex salts (e.g., Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258 (1973)), substances that improve the electrical conductivity, or substances that modify the dielectric anisotropy, viscosity, or alignment of the nematic phase. Substances of this type are described, for example, in German Patent Applications DE 22 09 127, DE 22 40 864, DE 23 21 632, DE 23 38 281, DE 24 50 088, DE 26 37 430, and DE 28 53 728.

[0413] The individual components of the preferred embodiments of the LC media according to the present invention listed above are either known or can be easily derived by those skilled in the art from the prior art, since their preparation methods are based on standard methods described in the literature.Corresponding compounds of formula CY are described, for example, in EP-A-0 364 538.Corresponding compounds of formula ZK are described, for example, in DE-A-26 36 684 and DE-A-33 21 373.

[0414] The LC media that can be used according to the present invention can be prepared in a conventional manner, for example by mixing one or more of the above-mentioned compounds with one or more polymerizable compounds as defined above, and optionally with further liquid crystal compounds and / or additives. Generally, the desired amount of the component used in the smaller amount is dissolved in the component that constitutes the main component, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, such as acetone, chloroform or methanol, and, after thorough mixing, remove the solvent again, for example by distillation. The present invention also relates to a method for preparing the LC media according to the present invention.

[0415] It goes without saying for those skilled in the art that the LC media according to the invention may also include compounds in which, for example, H, N, O, Cl, F are replaced by the corresponding isotopes, such as deuterium.

[0416] The following examples illustrate the present invention without limiting it. However, they provide those skilled in the art with preferred mixing ideas, along with the compounds preferably used, their respective concentrations and their combinations with one another. In addition, the examples illustrate what properties and property combinations are available.

[0417] Preferred mixture components are shown in Table A below.

[0418] In Table A, m and n are each independently an integer of 1 to 12, preferably 1, 2, 3, 4, 5, or 6; k is 0, 1, 2, 3, 4, 5, or 6; (O)C m H 2m+1 is C m H 2m+1 or O.C. m H 2m+1 means. In Table A, m and n are each independently an integer of 1 to 12, preferably 1, 2, 3, 4, 5, or 6; k is 0, 1, 2, 3, 4, 5, or 6; (O)C m H 2m+1 is C m H 2m+1 or O.C. m H 2m+1 means.

[0419] [Table 1]

[0420] [Table 2]

[0421] [Table 3]

[0422] Table 4

[0423] Table 5

[0424] Table 6

[0425] Table 7

[0426] Table 8

[0427] Table 9

[0428] Table 10

[0429] Table 11

[0430] Table 12

[0431] Table 13

[0432] [Table 14]

[0433] [Table 15]

[0434] [Table 16]

[0435] [Table 17]

[0436] [Table 18]

[0437] [Table 19]

[0438] In a preferred embodiment of the invention, the LC medium according to the invention comprises one or more compounds selected from the group consisting of the compounds from Table A.

[0439] In a first preferred embodiment of the invention, the LC media according to the invention, in particular those with positive dielectric anisotropy, comprise one or more compounds selected from the group consisting of the compounds from Table A1.

[0440] In a second preferred embodiment of the invention, the LC medium according to the invention, in particular one with negative dielectric anisotropy, comprises one or more compounds selected from the group consisting of the compounds from Table A2.

[0441] Table B shows possible chiral dopants which can be added to the LC media according to the invention.

[0442] [Table 20]

[0443] [Table 21]

[0444] The LC media preferably comprise 0 to 10% by weight, in particular 0.01 to 5% by weight, particularly preferably 0.1 to 3% by weight, of dopants. The LC media preferably comprise one or more dopants selected from the group consisting of the compounds from Table B.

[0445] Table C shows possible stabilizers that can be added to the LC media according to the invention, where n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and terminal methyl groups are not shown.

[0446] [Table 22]

[0447] [Table 23]

[0448] [Table 24]

[0449] [Table 25]

[0450] [Table 26]

[0451] [Table 27]

[0452] [Table 28]

[0453] [Table 29]

[0454] The LC medium preferably comprises 0 to 10% by weight, in particular 1 ppm to 5% by weight, particularly preferably 1 ppm to 1% by weight, of stabilizers. The LC medium preferably comprises one or more stabilizers selected from the group consisting of the compounds from Table C.

[0455] Table D shows exemplary reactive mesogenic compounds that can be used in the LC media according to the present invention.

[0456] [Table 30]

[0457] [Table 31]

[0458] [Table 32]

[0459] [Table 33]

[0460] [Table 34]

[0461] [Table 35]

[0462] Table 36

[0463] Table 37

[0464] Table 38

[0465] Table 39

[0466] Table 40

[0467] Table 41

[0468] Table 42

[0469] Table 43

[0470] Table 44

[0471] Table 45

[0472] [Table 46]

[0473] [Table 47]

[0474] [Table 48]

[0475] [Table 49]

[0476] In a preferred embodiment, the mixture according to the invention comprises one or more polymerizable compounds, preferably selected from the polymerizable compounds of formulae RM-1 to RM-176, of which the compounds RM-1, RM-4, RM-8, RM-17, RM-19, RM-35, RM-37, RM-39, RM-40, RM-41, RM-48, RM-52, RM-54, RM-57, RM-64, RM-74, RM-76, RM-88, RM-102, RM-103, RM-109, RM-117, RM-120, RM-121, RM-122, RM-139, RM-142, RM-143, RM-148 to RM-156, RM-162, RM-163 and RM-164 to RM-176 are particularly preferred.

[0477] Table E shows self-alignment additives for homeotropic alignment which can be used in the LC medium for SA-VA and SA-FFS displays according to the invention together with the polymerizable compounds of formula M.

[0478] [Table 50]

[0479] Table 51

[0480] Table 52

[0481] Table 53

[0482] Table 54

[0483] Table 55

[0484] Table 56

[0485] Table 57

[0486] Table 58

[0487] Table 59

[0488] Table 60

[0489] Table 61

[0490] [Table 62]

[0491] In a preferred embodiment, the LC media, SA-VA and SA-FFS displays according to the invention comprise one or more SA additives selected from the formulae SA-1 to SA-48, preferably from the formulae SA-14 to SA-48, very preferably from the formulae SA-20 to SA-34 and SA-44, in combination with one or more RMs of formula M. [Example]

[0492] The following examples illustrate the present invention without limiting it. However, they provide those skilled in the art with preferred mixing ideas, along with the compounds preferably used, their respective concentrations and their combinations with one another. In addition, the examples illustrate what properties and property combinations are available.

[0493] In addition, the following abbreviations and symbols are used: V0 is the capacitance threshold voltage [V] at 20°C, n e is the extraordinary refractive index at 20°C and 589 nm, n0 is the ordinary 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 at 20°C [mPa·s], K1 is the elastic constant for "splay" deformation at 20°C [pN], K2 is the elastic constant for "twist" deformation at 20°C [pN], K3 is the elastic constant for "bend" deformation [pN] at 20°C.

[0494] Unless otherwise specified, all concentrations in this application are given in weight percent and refer to the corresponding total mixture, including all solid or liquid crystal components, excluding solvent.

[0495] Unless otherwise specified, all temperature values ​​given in this application, such as the melting point T(C,N), the smectic (S) to nematic (N) phase transition T(S,N), and the clearing point T(N,I), are given in degrees Celsius (°C). mp denotes the melting point, cl.p. denotes the clearing point. Furthermore, C is the crystalline state, N is the nematic phase, S is the smectic phase, and I is the isotropic phase. The data between these symbols represent the transition temperatures.

[0496] All physical properties are or have been determined in accordance with "Merck Liquid Crystals, Physical Properties of Liquid Crystals", November 1997, Merck KGaA, Germany, and unless otherwise stated in each case, a temperature of 20°C applies, Δn is determined at 589 nm and Δε is determined at 1 kHz.

[0497] For the present invention, the term "threshold voltage" refers to the capacitive threshold (V), also known as the Freederickss threshold, unless otherwise specified. Also, in the examples, and as is generally usual, the threshold voltage is referred to as the 10% relative contrast (V 10 ) may also be given as the optical threshold.

[0498] Unless otherwise specified, the process of polymerizing the polymerizable compounds in the PSA displays, 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.

[0499] Unless otherwise specified, the methods for preparing the test cells and measuring their electro-optical and other properties are as or similar to those described hereinafter.

[0500] The display used for measuring the capacitive threshold voltage consisted of two flat, parallel glass outer plates separated by a gap of 25 μm, each with an inner electrode layer and an unrubbed polyimide alignment layer on top, which produces homeotropic edge alignment of the liquid crystal molecules.

[0501] Unless otherwise specified, a PSVA display or PSVA test cell used for tilt angle measurements consists of two flat, parallel glass outer plates separated by a 4 μm gap, each with an electrode layer on its inner side and a polyimide alignment layer on top, except that the two polyimide layers are rubbed antiparallel to each other to produce homeotropic edge alignment of the liquid crystal molecules. A PSVA display or test cell has the same structure but omits one or both polyimide layers.

[0502] The polymerizable compound is polymerized in the display or test cell by irradiation with UV light of a specified intensity for a specified time while simultaneously applying a voltage to the display (typically 10 V to 30 V AC, 1 kHz). In the examples, unless otherwise indicated, a metal halide lamp and an intensity of 100 mW / cm are used for polymerization. 2 The intensity is measured using a standard meter (high-pass Hoenle UV meter with UV sensor).

[0503] The tilt angle is determined using a Mueller matrix polarimeter "AxoScan" manufactured by Axometrics, Inc. Herein, low values ​​(i.e., large deviations from a 90° angle) correspond to large tilts. Unless otherwise stated, the term "tilt angle" refers to the angle between the LC director and the substrate, and "LC director" refers to the preferred orientation direction of the principal optical axes of the LC molecules in a layer of uniformly aligned LC molecules; in the case of calamitic, i.e., uniaxial, positively birefringent LC molecules, the "LC director" corresponds to the long molecular axis of the LC molecules.

[0504] <Comparative Example 1> The nematic LC host mixture C1 is formulated as follows:

[0505] [Table 63]

[0506] The mixture contains 1% of the compound of formula IB, CLY-3-O2, but no compound of formula IA.

[0507] <Comparative Example 2> The nematic LC host mixture C2 is formulated as follows:

[0508] [Table 64]

[0509] The mixture contains 9% of the compound of formula IA, COB(S)-2-O4, but no compound of formula IB.

[0510] <Example 1> The nematic LC host mixture N1 is formulated as follows:

[0511] [Table 65]

[0512] The mixture contains 5% of the compound of formula IA, COB(S)-2-O4, and 1% of the compound of formula IB, CLY-3-O2.

[0513] <Example 2> The nematic LC host mixture N2 is formulated as follows:

[0514] [Table 66]

[0515] The mixture contains 5% of the compound of formula IA, COB(S)-2-O4, and 1% of the compound of formula IB, CLY-3-O2.

[0516] <Example 3> The nematic LC host mixture N3 is formulated as follows:

[0517] [Table 67]

[0518] The mixture contains 5% of the compound of formula IA, COB(S)-2-O4, and 1% of the compound of formula IB, CLY-3-O2.

[0519] <Example 4> The nematic LC host mixture N4 is formulated as follows:

[0520] [Table 68]

[0521] The mixture contains 9% of the compound of formula IA, COB(S)-2-O4, and 1% of the compound of formula IB, CLY-3-O2.

[0522] <Polymerizable mixture> Polymerizable comparative mixtures PC1 and PC2 are prepared by adding 0.3% of polymerizable compound M1 and 0.015% of stabilizer S1 to the nematic LC host mixtures C1 or C2, respectively.

[0523] The polymerizable mixtures P1 to P4 according to the invention are prepared by adding 0.3% of polymerizable compound M1 and 0.015% of stabilizer S1 to the nematic LC host mixtures N1 to N4, respectively.

[0524] [ka]

[0525] <vhr> The VHR of the polymerizable mixture was measured in a TOYO 6254 instrument at 60 °C in a VA-VHR test cell before and after 40, 80, and 120 minutes of UV exposure at room temperature using a fluorescent UV lamp type C. The measurement cell had two substrates with a thickness of approximately 3 μm and an unrubbed polyimide layer JSR AL64101.

[0526] Light stress usually causes a decrease in the VHR of LC mixtures, so the smaller the absolute decrease in VHR value after stress, the better the performance for display applications. The results are shown in Table 1.

[0527]

[0528] [Table 69]

[0529] Table 1 shows that the VHR values ​​of the polymerizable mixtures P1 to P4 according to the invention are significantly higher compared to the polymerizable reference mixtures PC1 and PC2 which contain only one of the compounds of formula IA and formula IB.

[0530] <Tilt angle> UV photopolymerization was performed in a VA tilt test cell with a cell thickness of approximately 4 μm and two substrates with antiparallel rubbed polyimide layers (JALS-2096-R1) using a high-pressure Hg lamp at 50 mW / cm at room temperature. 2 The reaction was carried out at room temperature with 6 J of UV exposure.

[0531] The test cells were allowed to relax for at least 12 hours, after which the final tilt angles were measured and calculated using an Axometrics AxoScan®. The results are shown in Table 2.

[0532]

[0533] [Table 70]

[0534] It can be seen that the tilt angles produced in the polymerizable mixtures P1 to P4 according to the invention are as good as those in the polymerizable reference mixtures PC1 and PC2.

[0535] <Residual RM> After UV photopolymerization, the residual content (wt%) of unpolymerized RM in the mixture was measured. The lower the residual RM content after a certain time, the faster the polymerization rate. For this purpose, the polymerizable mixture was filled into a test cell and polymerized by UV exposure for 80 minutes at room temperature using a fluorescent UV lamp type C. After photopolymerization, the test cell was opened, and the mixture was dissolved in methyl ethyl ketone, washed out of the test cell, and analyzed by ultra-performance liquid chromatography (UPLC).

[0536] The results are shown in Table 3.

[0537]

[0538] [Table 71]

[0539] It can be seen that the residual RM content after polymerization in the polymerizable mixtures P1 to P4 according to the invention is as good as in the polymerizable reference mixtures PC1 and PC2.

[0540] In conclusion, the polymerizable mixtures P1-P4 according to the invention, which contain compounds of formulae IA and IB, allow for a significant increase in VHR and reliability after UV exposure, without adversely affecting other properties such as tilt generation or completeness of polymerization. This can be achieved even when using only small amounts of 1% of the compound of formula IB. These mixtures are therefore particularly suitable for use in PS-VA displays.< / vhr>

Claims

1. LC medium having negative dielectric anisotropy and comprising one or more polymerizable compounds, one or more compounds of the formula IA and one or more compounds of the formula IB. 【Chemistry 1】 wherein the individual radicals, which are identical or different at each occurrence, each have the following meaning independently of one another: R １ , R ２ is a linear, branched or cyclic alkyl group having 1 to 25 carbon atoms (provided that there are one or more non-adjacent CH ２ The groups are each formed by combining -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR ０ =CR ００ -, -C≡C-, 【Chemistry 2】 wherein one or more H atoms may be replaced by F or Cl, R ０ , R ００ is H or alkyl having 1 to 12 C atoms, L １ , L ２ is F or Cl.

2. LC medium according to claim 1, characterized in that the compound of the formula IA is selected from the group consisting of the formulae IA-1 to IA-10. 【Transformation 3】 【Chemistry 4】 (In the formula, R １２ represents alkyl having 1 to 7 C atoms, or alternatively cyclopropylmethyl, cyclobutylmethyl or cyclopentylmethyl.

3. LC medium according to claim 1, characterized in that the compound of the formula IB is selected from the group consisting of the following subformulae: 【Transformation 5】 (Wherein alkyl and alkyl ＊ each independently represents a linear alkyl group having 1 to 6 carbon atoms, and (O) represents an oxygen atom or a single bond.

4. LC medium according to claim 1, characterized in that the total proportion of compounds of the formula IB in the LC medium is 0.5 to 5% by weight.

5. LC medium according to claim 1, characterized in that it additionally comprises one or more compounds of the formula II 【Transformation 6】 wherein the individual radicals, each independently of one another, have the following meanings at each occurrence, which may be the same or different: R １ and R ２ is a linear, branched or cyclic alkyl group having 1 to 25 carbon atoms (provided that there are one or more non-adjacent CH ２ The groups are each formed by combining -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, CR ０ =CR ００ -, -C≡C-, 【Transformation 7】 wherein one or more H atoms may be replaced by F or Cl, R ０ , R ００ is H or alkyl having 1 to 12 C atoms, A １ and A ２ is obtained from the following formula: 【Transformation 8】 is a group selected from Z １ and Z ２ is -CH ２ CH ２ -, -CH=CH-, -CF ２ O-, -OCF ２ -, -CH ２ O-, -OCH ２ -, -CO-O-, -O-CO-, -C ２ F ４ -, -CF=CF-, -CH=CH-CH ２ O— or a single bond, L １ , L ２ , L ３ and L ４ are F, Cl, OCF ３ , C.F. ３ , C.H. ３ , C.H. ２ F or CHF2, Y is H, F, Cl, CF ３ , CHF ２ or CH3, L Ｃ is CH ３ or OCH3, a1 is 1 or 2; a2 is 0 or 1.

6. 6. LC medium according to claim 5, characterized in that it comprises one or more compounds of the formula II selected from the group consisting of the compounds of the formulae IIA, IIB, IIC and IID. 【Chemistry 9】 (In the ceremony R ２Ａ and R ２Ｂ are each independently H, an alkyl or alkenyl group having up to 15 C atoms, which group is unsubstituted or is CN or CF ３ or at least monosubstituted with halogen, provided that in addition, one or more CH ２ The groups are formed by -O-, -S-, etc. so that the O atoms are not directly linked to each other. 【Chemistry 10】 -C≡C-, -CF ２ O-, -OCF ２ may be replaced by —, —CO—O— or —O—CO—, L １ ~L ４ are each independently F, Cl, CF ３ or CHF ２ represents Y is H, F, Cl, CF ３ , CHF ２ or CH3, Z ２ , Z ２Ｂ , Z ２Ｄ are each independently 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-, -CH=CHCH ２ represents O-, p represents 0, 1 or 2, and q is the same or different and represents 0 or 1 in each occurrence.

7. LC medium according to claim 1, characterized in that it additionally comprises one or more compounds of the formula III. 【Chemistry 11】 (In the ceremony R １１ and R １２ each independently represent H, an alkyl or alkoxy group having 1 to 15 C atoms, provided that one or more CH ２ The group is formed so that the O atoms are not directly connected to each other. 【Chemistry 12】 -C≡C-, -CF ２ O-, -OCF ２ -, -CH=CH-, -O-, -CO-O- or -O-CO-, each of which may be replaced independently, in which one or more H atoms may additionally be replaced by halogen; A ３ occur independently 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 consisting of spiro[3.3]heptane-2,6-diyl, 1,4-bicyclo[2.2.2]octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl, and fluorene-2,7-diyl. represents provided that groups a), b) and c) may be mono- or polysubstituted with halogen atoms; n represents 0, 1 or 2; Z １ are each independently -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 represents -, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or a single bond, L １１ and L １２ are each independently F, Cl, CF ３ or CHF2, and W represents O or S.

8. LC medium according to claim 1, characterized in that it additionally comprises one or more compounds of the formula IV 【Chemistry 13】 (In the formula, R ４１ represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, R ４２ represents an unsubstituted alkyl group having 1 to 7 carbon atoms, an unsubstituted alkoxy group having 1 to 6 carbon atoms, or an unsubstituted alkenyl group having 2 to 7 carbon atoms.

9. LC medium according to claim 1, characterized in that it additionally comprises one or more compounds of the formula V 【Chemistry 14】 (In the formula, R 51 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms; R 52 represents an unsubstituted alkyl group having 1 to 7 C atoms, an unsubstituted alkoxy group having 1 to 6 C atoms, or an unsubstituted alkenyl group having 2 to 7 C atoms; 【Chemistry 15】 Z ５１ , Z ５２ are each independently —CH ２ -CH ２ -, -CH ２ represents —O—, —CH═CH—, —C≡C—, —COO— or a single bond; n is 1 or 2.

10. LC medium according to claim 1, characterized in that it additionally comprises one or more additives selected from the group consisting of stabilizers, chiral dopants, polymerization initiators and self-aligning additives.

11. LC medium according to claim 1, characterized in that it comprises one or more polymerizable compounds selected from the formula M. 【Chemistry 17】 wherein the individual radicals, which are identical or different at each occurrence, each have the following meaning independently of one another: R ａ and R ｂ are P, P-Sp-, H, F, Cl, Br, I, -CN, -NO ２ , -NCO, -NCS, -OCN, -SCN, SF ５ or a straight-chain or branched alkyl having 1 to 25 C atoms, provided that in addition there are one or more non-adjacent CH ２ The groups are each independently —C(R ０ ) = C(R ００ )-, -C≡C-, -N(R ００ )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, provided that in addition one or more H atoms may be replaced by F, Cl, Br, I, CN, P or P-Sp-, provided that B １ and / or B ２ contains saturated C atoms, and R ａ and / or R ｂ may also represent a group which can be linked to this saturated C atom via a spiro bond, where the group R ａ and R ｂ at least one of which represents or contains a group P or P-Sp-, P is a polymerizable group, Sp is a spacer group or a single bond; B １ and B ２ is an aromatic, heteroaromatic, alicyclic or heterocyclic group having 4 to 25 ring atoms, which may also contain fused rings, which group is unsubstituted or mono- or polysubstituted by L; Z ｂ is -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH ２ -, -CH ２ O-, -SCH ２ -, -CH ２ S-, -CF ２ O-, -OCF ２ -, -CF ２ S-, -SCF ２ -, -(CH ２ ) ｎ１ -, -CF ２ CH ２ -, -CH ２ CF ２ -, - (CF ２ ) ｎ１ -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, CR ０ R ００ or a single bond, R ０ and R ００ is H or alkyl having 1 to 12 C atoms, m is 0, 1, 2, 3 or 4; n1 is 1, 2, 3 or 4; L is P, P-Sp-, OH, CH ２ OH, F, Cl, Br, I, -CN, -NO ２ , -NCO, -NCS, -OCN, -SCN, -C(=O)N(R ｘ ) ２ , -C(=O)Y １ , -C(=O)R ｘ , -N(R ｘ ) ２ , optionally substituted silyl, optionally substituted aryl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, provided that in addition one or more H atoms may be replaced by F, Cl, P or P-Sp-, Y １ is a halogen, R ｘ is P, P-Sp-, H, halogen, linear, branched or cyclic alkyl having 1 to 25 C atoms (but in addition, one or more non-adjacent CH ２ The group may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that O and / or S atoms are not directly linked to one another, and in addition, one or more H atoms may be replaced by F, Cl, P or P-Sp-; an optionally substituted aryl or aryloxy group having 6 to 40 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 40 C atoms.

12. LC medium according to claim 1, characterized in that it comprises one or more polymerizable compounds selected from the following formulae: [Chemistry 18] 【Chemistry 19】 【Chemistry 20】 【Chemistry 21】 【Chemistry 22】 【Chemistry 23】 wherein the individual radicals, which are the same or different at each occurrence, each have the following meaning independently of one another: P １ , P ２ , P ３ is a vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane or epoxy group; Sp １ , Sp ２ , Sp ３ is a single bond or a spacer group, provided that in addition thereto one or more groups P １ -Sp １ -, P ２ -Sp ２ - and P ３ -Sp ３ - is R ａａ may also represent, provided that any group P １ -Sp １ -, P ２ -Sp ２ - and P ３ -Sp ３ At least one of - is R ａａ provided that it is different from R ａａ is H, F, Cl, CN or a linear or branched alkyl having 1 to 25 C atoms, provided that in addition there are one or more non-adjacent CH ２ The groups may each independently be —C(R ０ ) = C(R ００ )-, -C≡C-, -N(R ０ )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, provided that in addition one or more H atoms may be replaced by F, Cl, CN or P １ -Sp １ -, with the proviso that alkenyl and alkynyl groups have at least 2 C atoms and branched groups have at least 3 C atoms, R ０ , R ００ is H or alkyl having 1 to 12 C atoms, R ｙ and R ｚ are H, F, and CH ３ or CF ３ and X １ , X ２ , X ３ is —CO—O—, —O—CO— or a single bond, Z １ is -O-, -CO-, -C(R ｙ R ｚ ) - or -CF ２ CF ２ - and Z ２ , Z ３ is -CO-O-, -O-CO-, -CH ２ O-, -OCH ２ -, -CF ２ O-, -OCF ２ - or - (CH ２ ) ｎ -, where n is 2, 3 or 4; L is F, Cl, CN or a linear or branched, optionally monofluorinated or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, L', L" are H, F or Cl; r is 0, 1, 2, 3 or 4; s is 0, 1, 2 or 3; t is 0, 1 or 2; x is 0 or 1.

13. LC medium according to claim 1, characterized in that the polymerizable compound is present in polymerized form.

14. 10. A method for preparing an LC medium according to claim 1, comprising the steps of mixing one or more compounds of formulae IA and IB as defined in claim 1 with one or more polymerizable compounds as defined in claim 1, optionally with one or more further liquid crystal compounds and / or additives, and optionally polymerizing the polymerizable compounds.

15. LC display comprising an LC medium as defined in claim 1.

16. 16. An LC display according to claim 15, characterized in that it is a PS-VA, PS-IPS, PS-FFS or SA-VA display.

17. 1. An LC display comprising two substrates, at least one of which is transparent to light, an electrode on each substrate or two electrodes on only one of the substrates, and a layer of the LC medium according to claim 1 arranged between the substrates, wherein the polymerizable compound is polymerized between the substrates of the display by UV photopolymerization.

18. 18. A method for manufacturing an LC display according to claim 17, comprising the steps of providing an LC medium according to claim 1 between substrates of the display and polymerising the polymerisable compound by irradiating with UV light whilst applying a voltage to the electrodes of the display.

19. 10. Use of an LC medium according to claim 1 in an energy-saving LC display.

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