Liquid crystal medium comprising polymerizable compounds

Abstract

The present invention relates to a liquid crystal (LC) medium comprising a polymerisable compound as further specified in the description or claims and a self-aligning additive for homeotropic alignment. The medium is suitable for use in LC displays, in particular in LC displays of the polymer-stabilised alignment type.

Description

Technical Field

[0001] The present invention relates to a liquid crystal (LC) medium comprising a polymerisable compound as further specified in the description or claims and a self-aligning additive for homeotropic alignment. The medium is suitable for use in LC displays, in particular LC displays of the polymerisation-stabilised alignment type. Background Art

[0002] One of the liquid crystal display (LCD) modes currently used is the TN (twisted nematic) mode. However, the TN LCD has a disadvantage of strong contrast dependence on viewing angle.

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

[0004] In addition, OCB ("Optically Compensated Bend") displays are known which are based on the birefringence effect and have an LC layer with a so-called "bend" alignment and a generally positive dielectric anisotropy. When a voltage is applied, a realignment of the LC molecules perpendicular to the electrode surfaces occurs. In addition, OCB displays usually contain one or more birefringent optical retardation films to prevent undesired light transmittance of the bend cell in the dark state. OCB displays have wider viewing angles and shorter response times relative to TN displays.

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

[0006] In addition, so-called FFS (fringe field switching) displays have been reported (see in particular SH Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which contain two electrodes on the same substrate, one of which is structured in a comb-like manner and the other is unstructured. This generates a strong so-called "fringe field", i.e. a strong electric field close to the edge of the electrode, and such an electric field in the entire box, which has both a strong vertical component and a strong horizontal component. FFS displays have a small viewing angle dependence of the contrast. FFS displays usually contain an LC medium with positive dielectric anisotropy, and an alignment layer, usually an alignment layer of polyimide, which provides a planar alignment of the molecules of the LC medium.

[0007] FFS displays can be operated as active matrix or passive matrix displays. In the case of active matrix displays, the individual pixels are typically addressed by integrated non-linear active elements such as transistors (e.g., thin film transistors or "TFTs"), while in the case of passive matrix displays, the individual pixels are typically addressed according to multiplexing methods as known in the art.

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

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

[0010] In the newer types of VA displays, the uniform alignment of the LC molecules is limited to a number of relatively small domains within the LC cell. There can be disclinations between these domains, also called tilted domains. VA displays with tilted domains have greater contrast and viewing angle independence of the grey scales relative to conventional VA displays. In addition, this type of display is easier to produce, since additional surface treatment of the electrodes (e.g. by rubbing) for uniform alignment of the molecules in the switched-on state is no longer necessary. Instead, the preferential orientation of the tilt angle or pretilt angle is controlled by a special design of the electrodes.

[0011] In so-called MVA (multi-domain vertical alignment) displays, this is usually achieved by electrodes having protrusions that cause local pretilt. As a result, the LC molecules are aligned parallel to the electrode surface in different directions in different, defined cell areas when a voltage is applied. "Controlled" switching is thus achieved and the formation of interfering disclination lines is prevented. Although this arrangement improves the viewing angle of the display, it leads to a reduction in its light transmittance. A further development of the MVA uses protrusions only on one electrode side, while the opposite electrode has a slit, which improves the light transmittance. The slit electrode generates an inhomogeneous electric field in the LC cell when a voltage is applied, meaning that controlled switching is still achieved. To further improve the light transmittance, the spacing between the slit and the protrusion can be enlarged, but this in turn leads to a longer response time. In so-called PVA ("patterned VA"), the protrusions are made completely superfluous, since the two electrodes are structured on opposite sides by slits, which leads to increased contrast and improved light transmission, but this is technically difficult and makes the display more sensitive to mechanical influences ("tapping" etc.). However, for many applications, such as monitors and especially TV screens, it is required to shorten the response time and to improve the contrast and brightness (transmittance) of the display.

[0012] Another development is the so-called PS ("polymer stabilized") or PSA ("polymer stabilized alignment") type displays, for which the term "polymer stabilized" is occasionally also used. In these, small amounts (e.g. 0.3% by weight, typically <1% by weight) of one or more polymerizable compounds, preferably polymerizable monomeric compounds, are added to the LC medium and, after the LC medium has been charged into the display, are polymerized or crosslinked in situ (generally by UV photopolymerization) while optionally applying a voltage to the electrodes of the display. The polymerization takes place at a temperature at which the LC medium exhibits a liquid-crystalline phase, generally at room temperature. The addition of polymerizable mesogens or liquid-crystalline compounds (also called reactive mesogens or "RMs") to the LC mixture has proven to be particularly suitable.

[0013] Unless otherwise stated, the term "PSA" is used hereinafter when referring to the general polymer stabilized alignment type of displays, and "PS" is used when referring to specific display modes (eg PS-VA, PS-TN, etc.).

[0014] Furthermore, unless otherwise stated, the term "RM" is used hereinafter when referring to polymerisable mesogenic or liquid crystal compounds.

[0015] At the same time, the PS(A) principle is being used in various conventional LC display modes. Thus, for example, PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS and PS-TN displays are known. The polymerization of the RMs preferably takes place under an applied voltage in the case of PS-VA and PS-OCB displays, and with or without, preferably without, an applied voltage in the case of PS-IPS displays. As can be verified in a test cell, the PS(A) method leads to a pre-tilt in the cell. In the case of a PS-OCB display, for example, the curved structure can be stabilized so that the offset voltage is not required or can be reduced. In the case of a PS-VA display, this pre-tilt has a positive effect on the response time. For PS-VA displays, standard MVA or PVA pixel and electrode layouts can be used. However, in addition, it is also possible, for example, to use only one structured electrode side without protrusions to manage, which significantly simplifies production and simultaneously produces excellent contrast and excellent light transmittance.

[0016] PS-VA displays are described, for example, in EP 1 170 626 A2, US 6,861 ,107, US 7,169,449, US 2004 / 0191428 A1 , US 2006 / 0066793 A1 and US 2006 / 0103804 A1 .

[0017] Below the layer formed by the phase separated and polymerized RMs (which induce the above-mentioned tilt angle), PSA displays usually contain an alignment layer, for example of polyimide, which provides an initial alignment of the LC molecules prior to the polymer stabilization step.

[0018] Rubbed polyimide layers have been used as alignment layers for a long time. However, the rubbing process causes many problems, such as color difference (mura), contamination, electrostatic discharge problems, debris, etc. Usually, the effort and cost of manufacturing such polyimide layers are relatively high. Therefore, it is suggested to use polyimide layers prepared by photoalignment, or to self-align by adding suitable additives to the LC medium to replace the rubbed polyimide layers.

[0019] Furthermore, it has been observed that unfavorable interactions of the polyimide alignment layer with certain compounds of the LC medium often result in a reduction in the resistance of the display. Thus, the number of suitable and usable LC compounds is significantly reduced at the expense of display parameters such as viewing angle dependency, contrast and response time, which are intended to be improved by using such LC compounds. It is therefore desirable to omit the polyimide alignment layer.

[0020] For some display modes, this is achieved by adding self-aligning agents or additives to the LC medium, which induce the desired alignment, such as homeotropic alignment, in situ by a self-assembly mechanism. Thus, alignment layers can be omitted on one or both substrates. These display modes are also called "self-aligned", "self-aligning" or "self-aligning" (SA) modes.

[0021] In SA displays, a small amount, typically 0.1-2.5%, of a self-aligning additive is added to the LC medium. Suitable self-aligning additives are, for example, compounds having an organic core group and one or more polar anchoring groups attached thereto, which are able to interact with the substrate surface, causing the additive to align on the substrate surface and also inducing the desired alignment in the LC molecules. Preferred self-aligning additives comprise, for example, a mesogenic group and a linear or branched alkyl side chain, which is terminated with one or more polar anchoring groups, which are, for example, selected from hydroxyl, carbonyl, amino or thiol groups. The self-aligning additive may also contain one or more polymerizable groups, which can be polymerized under similar conditions as the RMs used in the PSA process.

[0022] SA-VA (self-aligned VA) displays have been disclosed so far. Suitable self-aligned additives that induce homeotropic alignment, especially for VA mode displays, are disclosed in, for example, US 2013 / 0182202 A1, US 2014 / 0138581 A1, US 2015 / 0166890 A1 and US 2015 / 0252265 A1.

[0023] The SA mode can also be used in combination with the PSA mode.The LC medium for such a combined mode display thus contains both one or more RMs and one or more self-aligning additives.

[0024] Similar to the conventional LC displays described above, PSA displays can be operated as active matrix or passive matrix displays. In the case of active matrix displays, the individual pixels are typically addressed by integrated non-linear active elements such as transistors (e.g. thin film transistors "TFT"), while in the case of passive matrix displays, the individual pixels are typically addressed by multiplexing methods as known in the art.

[0025] Particularly for monitors and especially TV applications, there is a continuing demand for optimization of the response time of liquid crystal displays as well as of the contrast and brightness (and therefore also the transmittance). The PSA method can offer key advantages here. In particular in the case of PS-VA, PS-IPS, PS-FFS and PS-positive-VA displays, a reduction in the response time associated with the pretilt measurable in the test cell can be achieved without significant detrimental effects on other parameters.

[0026] The prior art has already proposed the use of optionally fluorinated biphenyl diacrylate or diphenyl dimethacrylate as RM in PSA displays.

[0027] However, the problem arises that not all combinations of LC mixtures and one or more RMs are suitable for PSA displays, because, for example, insufficient tilt or no tilt at all is established, or because, for example, the VHR is insufficient for TFT display applications. Furthermore, it has been found that the LC mixtures and RMs known from the prior art still have some disadvantages when used in PSA displays. Therefore, not every known RM that is soluble in an LC mixture is suitable for PSA displays. Furthermore, apart from the direct measurement of the pretilt in PSA displays, it is often difficult to find suitable selection criteria for the RMs. If it is desired to carry out the polymerization with the aid of UV light without the addition of photoinitiators, which may be advantageous for certain applications, the choice of suitable RMs becomes even smaller.

[0028] In addition, the selected LC host mixture / RM combination should have the lowest possible rotational viscosity and the best possible electrical properties. In particular it should have the highest possible VHR. In PSA displays, a high VHR after irradiation with UV light is particularly desirable, since UV exposure is an essential part of the display production process and also occurs as normal exposure during operation of the manufactured display.

[0029] In particular, it is desirable to make available novel materials for PSA displays which produce appropriately small pretilt angles. Preferred materials are those which, during polymerization, produce lower tilt angles for the same exposure time than hitherto known materials and / or by using them, the desired results can also be achieved after shorter exposure times. As a result, the production time ("takt time") of the display can be shortened and the costs of the production process can be reduced. However, in combination with other polymerizable components, such as self-aligning additives for homeotropic alignment, the tilt angle can also become too low. In this case, if the LC medium is desired, the tilt generation behavior is adjusted more.

[0030] Another problem in producing PSA displays is the presence or removal of residual amounts of unpolymerized RMs, particularly after the polymerization step used to create the pretilt angle in the display. For example, such unreacted RMs may adversely affect the properties of the display by polymerizing in an uncontrolled manner, for example, after the display is made, during operation.

[0031] Therefore, PSA displays known from the prior art often show the undesirable effect of so-called "image sticking" or "image burning", i.e. the image produced by brief addressing of individual pixels in an LC display remains visible even after the electric field in these pixels has been switched off or after other pixels have been addressed.

[0032] This "image sticking" can occur on the one hand if LC host mixtures with a low VHR are used. The UV components of sunlight or backlighting can trigger undesirable decomposition reactions of the LC molecules and thus the generation of ionic or free-radical impurities. These can accumulate, in particular at the electrodes or alignment layers, where they can reduce the effectively applied voltage. This effect can also be observed in conventional LC displays without polymer components.

[0033] In addition, additional "image sticking" effects due to the presence of unpolymerized RMs are often observed in PSA displays. Uncontrolled polymerization of residual RMs is initiated here by UV light from the environment or from the backlight. In the switched display area, this changes the tilt angle after a number of addressing cycles. As a result, a change in the transmittance can occur in the switched area, while it remains unchanged in the unswitched area.

[0034] It is therefore desirable that the polymerization of RMs during the production of PSA displays is carried out as completely as possible and that the presence of unpolymerized RMs in the display is excluded as much as possible or reduced to a minimum. Therefore, there is a need for RM and LC mixtures which enable or support highly efficient and complete polymerization of RMs. Furthermore, a controlled reaction of the residual RM amount is desirable. This would be simpler if the RMs could polymerize faster and more efficiently than the hitherto known materials.

[0035] Another problem observed in the operation of PSA displays is the stability of the pretilt angle. Thus, it is observed that the pretilt angle (which is generated during the manufacturing process of the display by polymerizing the RM as described above) does not remain constant, but deteriorates after the display is subjected to voltage stress during its operation. This can have a negative impact on the display performance, for example by increasing the black state transmittance and thus reducing the contrast.

[0036] Another problem to be addressed is that prior art RMs do often have high melting points and do show only limited solubility in many currently common LC mixtures and therefore often tend to crystallize out spontaneously from the mixture. Furthermore, the risk of spontaneous polymerization prevents the LC host mixture from being warmed in order to dissolve the polymerizable components, which means that the best solubility that can be achieved is even necessary at room temperature. Furthermore, there is a risk of separation, for example when the LC medium is introduced into an LC display (chromatographic effect), which can greatly impair the homogeneity of the display. This is further increased by the fact that the LC medium is usually introduced at low temperature to reduce the risk of spontaneous polymerization (see above), which in turn has an adverse effect on the solubility.

[0037] Another problem observed in the prior art is that the use of conventional LC media in LC displays, including but not limited to PSA type displays, often results in color aberrations in the display, especially when the LC media is filled in a display cell manufactured using a one drop filling (ODF) method. This phenomenon is also known as "ODF color aberration". It is therefore desirable to provide an LC medium that results in a small ODF color aberration.

[0038] Another problem observed in the prior art is that LC media used in PSA displays, including but not limited to displays of the PSA type, often exhibit high viscosities and, therefore, long switching times. In order to reduce the viscosity and switching times of the LC media, it has been proposed in the prior art to add LC compounds having alkenyl groups. However, it has been observed that LC media containing alkenyl compounds often show reduced reliability and stability, as well as a reduction in the VHR, especially after exposure to UV radiation. Especially for use in PSA displays, this is a considerable disadvantage, since in PSA displays the photopolymerization of the RMs is usually carried out by exposure to UV radiation, which can lead to a reduction in the VHR in the LC media.

[0039] There is therefore still a great need for PSA displays and for LC media and polymerizable compounds for use in such displays which do not exhibit the disadvantages mentioned above or exhibit these disadvantages only to a small extent and have improved properties.

[0040] In particular, there is a great need for PSA displays and LC media and polymerizable compounds for such PSA displays which enable high specific resistances over a large operating temperature range, short response times even at low temperatures and low threshold voltages, low pretilt angles, a large number of grayscale levels, high contrast and wide viewing angles, high reliability and high values ​​of VHR after UV exposure and, in the case of polymerizable compounds, low melting points and high solubility in LC host mixtures. In PSA displays for mobile applications, it is particularly desirable to have available LC media which exhibit low threshold voltages and high birefringence.

[0041] In the prior art, several classes of RMs have been reported for use in PSA displays, such as RMs having a biphenyl or terphenyl mesogenic core and two or three polymerizable acrylate or methacrylate groups attached thereto. Biphenyl RMs were shown to exhibit limited polymerization speeds, but good reliability parameters, such as high VHR or tilt stability, whereas terphenyl RMs were shown to exhibit fast polymerization speeds, but limited reliability parameters. It is therefore desirable to have available RMs that exhibit both fast polymerization speeds and good reliability parameters.

[0042] The present invention is based on the object of providing novel suitable materials for use in PSA displays, in particular RMs and LC media comprising them, which materials do not have the disadvantages mentioned above or have these disadvantages to a reduced extent.

[0043] In particular, the present invention is based on the object of providing RMs for PSA displays and LC media containing them which allow very high specific resistance values, high VHR values, high reliability, low threshold voltage, short response time, high birefringence, show good UV absorption (especially at longer wavelengths), allow rapid and complete polymerization of the RM, allow a suitable tilt angle to be generated preferably as quickly as possible, allow a high stability of the pretilt (even after longer times and / or after UV exposure), reduce or prevent the occurrence of "image sticking" and "ODF color shift" in the display, and in the case of RMs, polymerize as quickly and completely as possible and show high solubility in the LC medium, which usually serves as a host mixture in PSA displays.

[0044] It is a further object of the present invention to provide RMs for PSA displays which show a fast polymerization speed and good reliability parameters, such as high VHR or tilt stability.

[0045] It is a further object of the present invention to provide novel RMs, in particular for optical, electro-optical and electronic applications, and to provide suitable processes and intermediates for their preparation.

[0046] This object has been achieved according to the invention by means of materials and methods as described in the present application. In particular, it has surprisingly been found that the use of RMs of formula I as described below in combination with self-aligning additives of formula II allows to achieve the advantageous effects as described above. The compounds of formula I are characterized in that they contain a mesogenic core having one or more benzene or naphthalene rings, one or more polymerizable reactive groups attached thereto and one or more methoxymethyl substituents attached thereto.

[0047] Surprisingly, it has been found that the use of these RMs and LC media comprising them in PSA displays promotes fast and complete UV photopolymerization, especially at longer UV wavelengths in the range of 300-380 nm and especially above 320 nm (even without added photoinitiator), leads to the rapid generation of suitable and stable pretilt angles, reduces image stickiness and ODF color differences in the display, leads to high reliability and high VHR values ​​after UV photopolymerization, especially in the case of LC host mixtures containing LC compounds with alkenyl groups, and enables fast response times, low threshold voltages and high birefringence to be achieved.

[0048] Furthermore, the RMs according to the invention have a low melting point, good solubility in a wide range of LC media, especially in commercially available LC host mixtures for PSA applications, and a low tendency to crystallize. Furthermore, they show good absorption at longer UV wavelengths, especially in the range of 300-380 nm, and enable fast and complete polymerization with little residual unreacted RM in the cell.

[0049] It has also been surprisingly found that the RMs according to the invention combine fast polymerization speeds (which are similar to terphenyl RMs) with good reliability parameters similar to biphenyl RMs. This results in superior overall performance compared to prior art RMs.

[0050] WO 2014 / 142168 A1 discloses an LC alignment agent containing a crosslinkable compound having a photoreactive group, and specifically discloses the following compound:

[0051]

[0052] However, this document neither discloses nor mentions the RMs disclosed and claimed below, or their use in PSA displays and the advantages achieved thereby. Summary of the invention

[0053] The present invention relates to a liquid crystal medium comprising

[0054] a polymerizable component A) comprising, preferably consisting of, one or more polymerizable compounds, at least one of which is a compound of formula I,

[0055] a liquid crystal (LC) component B), hereinafter also referred to as "LC host mixture", which comprises, preferably consists of, one or more mesogenic or liquid crystal compounds, and

[0056] - one or more self-aligning additives for vertical alignment of formula II

[0057] Wherein formula I and II are defined as follows:

[0058] P-Sp-A 1 -(Z 1 -A 2 ) z -RI

[0059] where the individual radicals, independently of one another and identically or differently on each occurrence, have the following meanings:

[0060] P represents a polymerizable group,

[0061] Sp represents a spacer group or a single bond,

[0062] A 1 ,A 2 is independently benzene or naphthalene, which is optionally substituted by one or more groups L, L 11 or P-Sp-substituted, wherein at least one group A 1 or A 2 At least one substituent L 11 replace,

[0063] -Z 1 Represents -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -(CH2) n1 -, -CF2CH2-, -CH2CF2-, -(CF2) n1 -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH2-CH2-CO-O-, -O-CO-CH2-CH2-, -CR 0 R 00 - or single key,

[0064] R 0 ,R 00 are independently H or alkyl having 1-12 C atoms,

[0065] L 11represents -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7, preferably -CH2-O-CH3,

[0066] R stands for H, L, L 11 , P-Sp- or -Sp(P)2,

[0067] L represents F, Cl, -CN, P-Sp- or a straight-chain, branched or cyclic alkyl radical having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl,

[0068] z represents 0, 1, 2, or 3, and

[0069] n1 means 1, 2, 3 or 4;

[0070] MES-R a II

[0071] in

[0072] MES is a rod-shaped mesogenic group comprising two or more rings, which are directly or indirectly linked to one another or which are fused to one another, whose rings are optionally substituted and whose mesogenic groups are optionally additionally substituted by one or more polymerizable groups, which are linked directly or via a spacer to the MES, and

[0073] R a is a polar anchoring group, located at the terminal position of the rod-shaped mesogenic group MES and the anchoring group comprises at least one carbon atom and at least one group selected from -OH, -SH, -COOH, -CHO or a primary or secondary amine functional group, preferably one or two OH groups, and it optionally contains one or two polymerizable groups P.

[0074] The liquid-crystalline component B) of the liquid-crystalline media according to the invention is also referred to below as "LC host mixture" or "LC component B)" and preferably comprises one or more, preferably at least two, mesogenic or LC compounds selected from non-polymerizable, low molecular weight compounds.

[0075] The invention furthermore relates to a liquid-crystalline medium or an LC display as described above, in which the compound of the formula I or the polymerisable compound of component A) is polymerised.

[0076] Furthermore, the present invention relates to a process for preparing a liquid-crystalline medium as described above and below, comprising the step of mixing one or more mesogens or LC compounds, or an LC host mixture or LC component B), as described above and below, with one or more compounds of formula I and optionally further LC compounds and / or additives.

[0077] The present invention furthermore relates to the use of the LC media according to the invention in PSA displays, in particular in PSA displays containing a liquid-crystalline medium, for generating a tilt angle in the liquid-crystalline medium by in situ polymerization of the compound(s) of the formula I in the PSA display, preferably in an electric or magnetic field.

[0078] The invention furthermore relates to LC displays, in particular PSA displays, particularly preferably PS-VA, PS-UB-FFS or PS-positive-VA displays, comprising one or more compounds of the formulae I and II respectively or liquid-crystalline media according to the invention.

[0079] The invention furthermore relates to the use of compounds of the formula I and LC media according to the invention in polymer-stabilized SA-VA displays, and polymer-stabilized SA-VA displays comprising one or more compounds of the formula I or LC media according to the invention.

[0080] The invention furthermore relates to LC displays comprising polymers obtainable by polymerizing the LC media according to the invention, preferably PSA displays, very preferably PS-VA, PS-UB-FFS or polymer-stabilized SA-VA displays.

[0081] Furthermore, the present invention relates to an LC display of the PSA type comprising two substrates, at least one of which is optically transparent, one electrode provided on each substrate or two electrodes provided on only one substrate, and a layer of a liquid-crystalline medium located between the substrates, the liquid-crystalline medium comprising a liquid-crystalline medium as described above and below, wherein the polymerizable compounds are polymerized between the substrates of the display.

[0082] Furthermore, the invention relates to a method for producing an LC display as described above and below, comprising the steps of filling or otherwise providing a liquid-crystalline medium according to the invention as described above and below between substrates of the display, and polymerizing the polymerizable compounds.

[0083] The PSA displays according to the invention have two electrodes, preferably in the form of transparent layers, which are applied to one or both of the substrates. In some displays, for example in PS-VA or polymer-stabilized SA-VA displays, one electrode is applied to each of the two substrates. In other displays, for example in PS-positive-VA or PS-IPS displays, the two electrodes are applied to only one of the two substrates.

[0084] In a preferred embodiment, the polymerisable components polymerise in the LC display when a voltage is applied to the electrodes of the display.

[0085] The polymerizable compounds of the polymerizable component are preferably polymerized by photopolymerization, very preferably by UV-photopolymerization.

[0086] Prior art document WO2014 / 142168A1 discloses an LC alignment agent which is crosslinkable and photoreactive and contains a benzyloxymethyl group (which is designated as a crosslinkable group). However, in order to initiate the crosslinking reaction of this benzyloxymethyl group, similar to phenolic resins, a strong acid is required. However, this benzyloxymethyl group does not react under the polymerization conditions as used for the compounds of formula I according to the present invention. Therefore, the CH2OCH3 group in the present application is not considered to be within the meaning of the term "polymerizable group" as used herein.

[0087] The conditions for polymerizing the compound of formula I are preferably selected such that L 11 The (e.g. CH2OCH3) substituents do not participate in the polymerization reaction. Preferably, the LC media disclosed and claimed in the present application do not contain such that L 11 (eg CH2OCH3) groups can participate in the cross-linking reaction of photoacids or other additives.

[0088] Details

[0089] When used in vertically self-aligned PSA displays, the compounds of formula I exhibit the following advantageous properties:

[0090] - suitable tilt generation within a certain process window,

[0091] - Rapid polymerization after UV treatment, resulting in minimal RM residue,

[0092] -High voltage holding ratio after UV treatment,

[0093] - good tilt stability,

[0094] - sufficient stability against heat,

[0095] - Sufficient solubility in organic solvents commonly used in display manufacturing.

[0096] In particular, the compounds of formula I combine a fast polymerization speed similar to that of terphenyl RMs with good reliability parameters similar to those of biphenyl RMs. This results in superior overall performance of the compounds compared to prior art RMs when used in PSA displays.

[0097] In the compounds of formula I, one or more methoxymethylene substituents L are found on the phenyl ring or naphthylene ring. 11 It can enhance the excellent properties of the compound, such as fast polymerization speed and good reliability. However, the substituent L 11 A polymerizable or crosslinkable group that is not specified should participate in polymerization reactions of the compound.

[0098] Therefore, a preferred embodiment of the present invention relates to the use of compounds of formula I in polymerization reactions, wherein the polymerization conditions of the group P are selected such that the methoxymethylene substituent or the group L 11 Does not participate in polymerization reaction.

[0099] Unless otherwise indicated, compounds of the formula I are preferably selected from achiral compounds.

[0100] As used herein, the terms "active layer" and "switchable layer" mean in an electro-optical display, for example in an LC display, a layer comprising one or more molecules with structural and optical anisotropy (for example LC molecules), which molecules change their orientation when subjected to an external stimulus such as an electric or magnetic field, which results in a change in the transmittance of the layer for polarized or unpolarized light.

[0101] As used herein, the terms "tilt" and "tilt angle" are to be understood as meaning the tilted alignment of the LC molecules of the liquid-crystalline medium relative to the cell surface in an LC display, here preferably a PSA display. The tilt angle here denotes the average angle (<90°) between the longitudinal molecular axis of the LC molecules (LC director) and the plane-parallel outer plates forming the LC cell. Low values ​​of the tilt angle here (i.e. large deviations from an angle of 90°) correspond to large tilts. A suitable method for measuring the tilt angle is given in the examples. Unless otherwise stated, the values ​​of the tilt angle disclosed above and below relate to this method of measurement.

[0102] As used herein, the terms "reactive mesogen" and "RM" are understood to mean a compound comprising a mesogenic or liquid crystal backbone and attached thereto one or more functional groups suitable for polymerization, also referred to as "polymerizable groups" or "P".

[0103] Unless otherwise indicated, the term "polymerizable compound" as used herein is to be understood as a polymerizable monomeric compound.

[0104] A SA-VA display according to the invention will be of polymer-stabilized mode, since it contains a liquid-crystalline medium having an RM of formula I or is produced by using a liquid-crystalline medium containing an RM of formula I. Therefore, as used herein, the term "SA-VA display", when referring to a display according to the invention, will be understood to mean a polymer-stabilized SA-VA display, even if this is not explicitly mentioned.

[0105] As used herein, the term "low molecular weight compound" is understood to mean a compound that is monomeric and / or not prepared by polymerization, as opposed to a "polymeric compound" or "polymer."

[0106] As used herein, the term "non-polymerizable compound" is understood to mean a compound that does not contain functional groups suitable for polymerization under the conditions normally applied to RM polymerization.

[0107] As used herein, the term "mesogenic group" is known to those skilled in the art and is described in the literature and refers to a group that substantially contributes to the generation of a liquid crystal (LC) phase in a low molecular weight or polymeric substance due to its anisotropy of attraction and repulsion interactions. A compound containing a mesogenic group (mesogenic compound) does not necessarily have an LC phase per se. A mesogenic compound may also exhibit LC phase behavior only after mixing with other compounds and / or after polymerization. Typical mesogenic groups are, for example, rigid rod-shaped or disc-shaped units. Terms and definitions used in connection with mesogenic or LC compounds are given in Pure Appl. Chem. 2001, 73 (5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368.

[0108] As used herein, "rod-like" mesogenic groups are rod-like mesogenic groups, as opposed to disc-like (disc-like groups). It may have side substituents and terminal substituents on the rod-like core. Terminal substituents are those located at the tip of the rod-like shape. The rod-like core is usually composed of an organic group, and is usually preferably composed of a combination of two or more ring systems. In the case of three or more ring systems, these are connected in a substantially linear manner, which results in a rod-like shape (e.g., terphenyl). The rings may be connected by a single bond, connected by a small organic group (bridge), or may be condensed rings, wherein a single bond is preferred.

[0109] As used herein, the term "spacer" (hereinafter also referred to as "Sp") is known to those skilled in the art in the art and is described in the literature, see for example Pure Appl. Chem. 2001, 73 (5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. As used herein, the term "spacer" or "spacer" refers to a flexible group, for example an alkylene group, which is connected to the mesogenic group or polymerizable group (s) in the polymerizable mesogenic compound.

[0110] In context, represents a trans-1,4-cyclohexylene ring, and It represents a 1,4-phenylene ring.

[0111] In the group In, the single bond shown between two ring atoms can be attached to any free position of the benzene ring.

[0112] "Organic group" in this context means a carbon or hydrocarbon group.

[0113] "Carbon group" means a mono- or polyvalent organic group containing at least one carbon atom, wherein the group contains no other atoms (e.g. -C≡C-) or optionally contains one or more other atoms, such as N, O, S, B, P, Si, Se, As, Te or Ge (e.g. carbonyl, etc.). The term "hydrocarbyl group" means a carbon group which additionally contains one or more H atoms and optionally one or more heteroatoms, such as N, O, S, B, P, Si, Se, As, Te or Ge.

[0114] "Halogen" means F, Cl, Br or I, preferably F or Cl.

[0115] -CO-, -C(=O)- and -C(O)- represent carbonyl groups, i.e.

[0116] The carbon or hydrocarbon group can be a saturated or unsaturated group. Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. Carbon or hydrocarbon groups with more than 3 C atoms can be straight chain, branched and / or cyclic and can also contain spiro connections or condensed rings.

[0117] The terms "alkyl", "aryl", "heteroaryl" and the like also include polyvalent groups such as alkylene, arylene, heteroarylene and the like.

[0118] The term "aryl" refers to an aromatic carbon group or a group derived therefrom. The term "heteroaryl" refers to an "aryl" as defined above containing one or more heteroatoms (preferably selected from N, O, S, Se, Te, Si and Ge).

[0119] Preferred carbon and hydrocarbon radicals are optionally substituted, linear, branched or cyclic alkyl, alkenyl, alkynyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxy radicals having 1 to 40, preferably 1 to 20, very preferably 1 to 12 C atoms, optionally substituted aryl or aryloxy radicals having 5 to 30, preferably 6 to 25 C atoms, or optionally substituted alkylaryl, aralkyl, alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl, arylcarbonyloxy and aryloxycarbonyloxy radicals having 5 to 30, preferably 6 to 25 C atoms, where one or more C atoms may also be replaced by heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.

[0120] Further preferred carbon and hydrocarbon groups are C1-C 20 Alkyl, C2-C 20 Alkenyl, C2-C 20 Alkynyl, C3-C 20 Allyl, C4-C 20 Alkyldiene, C4-C 20 Polyene, C6-C 20 Cycloalkyl, C4-C 15 Cycloalkenyl, C6-C 30 Aryl, C6-C 30 Alkyl aryl, C6-C 30 Arylalkyl, C6-C 30 Alkyl aryloxy, C6-C 30 Arylalkoxy, C2-C 30 Heteroaryl, C2-C 30 Heteroaryloxy.

[0121] Particularly preferred is C1-C 12 Alkyl, C2-C 12 Alkenyl, C2-C 12 Alkynyl, C6-C 25 Aryl and C2-C 25 Heteroaryl.

[0122] Further preferred carbyl and hydrocarbon radicals are straight-chain, branched or cyclic alkyl radicals having 1 to 20, preferably 1 to 12 C atoms, which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I or CN, and in which one or more non-adjacent CH2 groups can each be replaced independently of one another by -C(R x )=C(R x )-、-C≡C-、-N(R x )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other.

[0123] R x Preferably it represents H, F, Cl, CN, a straight-chain, branched or cyclic alkyl chain having 1 to 25 C atoms, wherein, in addition, one or more non-adjacent C atoms may be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, and wherein one or more H atoms may be replaced by F or Cl, or an optionally substituted aryl or aryloxy group having 6 to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxy group having 2 to 30 C atoms.

[0124] Preferred alkyl groups are, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, dodecyl, trifluoromethyl, perfluoro-n-butyl, 2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, and the like.

[0125] Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl, pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl and the like.

[0126] Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl, pentynyl, hexynyl, octynyl and the like.

[0127] Preferred alkoxy groups are, for example, methoxy, ethoxy, 2-methoxyethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, 2-methylbutoxy, n-pentoxy, n-hexyloxy, n-heptyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, n-undecyloxy, n-dodecyloxy, and the like.

[0128] Preferred amino groups are, for example, dimethylamino, methylamino, methylphenylamino, phenylamino and the like.

[0129] Aryl and heteroaryl groups may be monocyclic or polycyclic, i.e. they may contain one ring (e.g. phenyl) or two or more rings, which may also be fused (e.g. naphthyl) or covalently bonded (e.g. biphenyl), or a combination of fused and linked rings. Heteroaryl contains one or more heteroatoms, preferably selected from O, N, S and Se.

[0130] Particularly preferred are mono-, bi- or tricyclic aryl radicals having 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl radicals having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6- or 7-membered aryl and heteroaryl radicals, in which, in addition, one or more CH groups may be replaced by N, S or O in such a way that the O atoms and / or S atoms are not directly connected to one another.

[0131] Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl, [1,1':3',1"]-terphenyl-2'-yl, naphthyl, anthracenyl, binaphthyl, phenanthrenyl, 9,10-dihydro-phenanthrenyl, pyrene, dihydropyrene, Perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, and the like.

[0132] Preferred heteroaryl groups are, for example, 5-membered rings such as pyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole, furan, thiophene, selenophene, Azoles, Isopropylamine Azoles, 1,2-thiazoles, 1,3-thiazoles, 1,2,3- Oxadiazole, 1,2,4- Oxadiazole, 1,2,5- Oxadiazole, 1,3,4- oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, a 6-membered ring such as pyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine or a fused group such as indole, isoindole, indolizine, indazole, benzimidazole, benzotriazole, purine, naphthyimidazole, phenanthimidazole, pyridimidazole, pyrazimidazole, quinoxalimidazole, benzotriazole, Azoles, naphtho Azoles, anthracenes Azoles, phenanthracenes Azoles, Isopropylamine azole, benzothiazole, benzofuran, isobenzofuran, dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, benzisoquinoline, acridine, phenothiazine, phen oxazine, benzopyridazine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthridine, phenanthroline, thieno[2,3b]thiophene, thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene, dibenzothiophene, benzothiophene, benzothiadiazolethiophene, or a combination of these groups.

[0133] The aryl and heteroaryl groups mentioned above and below may also be substituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl or other aryl or heteroaryl groups.

[0134] (Non-aromatic) alicyclic and heterocyclic groups include both saturated rings, i.e. rings containing only single bonds, and partially unsaturated rings, i.e. those which may also contain multiple bonds. The heterocyclic ring contains one or more heteroatoms, preferably selected from Si, O, N, S and Se.

[0135] (Non-aromatic) alicyclic groups and heterocyclic groups can be monocyclic, i.e. contain only one ring (e.g. cyclohexane), or polycyclic, i.e. contain multiple rings (e.g. decalin or bicyclooctane). Saturated groups are particularly preferred. In addition, mono-, bi- or tricyclic groups with 5-25 ring atoms are preferred, which optionally contain fused rings and are optionally substituted. Further preferred are 5-, 6-, 7- or 8-membered carbocyclic groups, wherein in addition, one or more C atoms may be replaced by Si and / or one or more CH groups may be replaced by N and / or one or more non-adjacent CH2 groups may be replaced by-O- and / or-S-.

[0136] Preferred alicyclic and heterocyclic groups are, for example, 5-membered groups such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran, pyrrolidine; 6-membered groups such as cyclohexane, silinane, cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dihydropyran, 1,4-dihydrothio ... alkane, 1,3-dithiane, piperidine; 7-membered groups such as cycloheptane; and fused groups such as tetralin, decalin, indane, bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindan-2,5-diyl.

[0137] Preferred substituents for the above-mentioned cyclic groups are, for example, solubility-promoting groups, such as alkyl or alkoxy groups; electron-withdrawing groups, such as fluorine, nitro or nitrile; or substituents for increasing the glass transition temperature (Tg) of the polymer, especially bulky groups, such as tert-butyl or optionally substituted aromatic groups.

[0138] The preferred substituents of the above cyclic groups are also referred to as "L S ", for example, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R x )2, -C(=O)Y 1 、-C(=O)R x 、-N(R x )2, a straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy group having 1 to 25 C atoms, in which one or more H atoms may be optionally replaced by F or Cl, an optionally substituted silyl group having 1 to 20 Si atoms, or an optionally substituted aryl group having 6 to 25, preferably 6 to 15 C atoms.

[0139] Where R xrepresents H, F, Cl, CN, or a straight-chain, branched or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by F, Cl, P- or P-Sp-, and

[0140] Y 1 Represents halogen.

[0141] "Substituted silyl or aryl" preferably means that it is replaced by halogen, -CN, R 0 、-OR 0 、-CO-R 0 、-CO-OR 0 、-O-CO-R 0 OR-O-CO-OR 0 Substitution, where R 0 represents H or an alkyl group having 1 to 20 C atoms.

[0142] Particularly preferred substituents L S For example, F, Cl, CN, NO2, CH3, C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5, and phenyl.

[0143] Preferably

[0144] wherein L has one of the meanings indicated above.

[0145] The polymerizable group P is a group suitable for polymerization reactions (e.g. free radical or ionic chain polymerization, addition polymerization or condensation polymerization), or a group suitable for polymer-analogous reactions (e.g. addition or condensation on the polymer backbone). Particularly preferred are groups for chain polymerization, in particular those containing a C=C double bond or a -C≡C- triple bond, and groups suitable for ring-opening polymerization, such as oxetane or epoxy groups.

[0146] Preferred groups P are selected from the group consisting of:

[0147] CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -(O) k3 -、CW1 =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-, where W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently represents Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms, W 7 and W 8 Each independently represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, which is optionally substituted by one or more groups L different from P-SP- as defined above, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 represents an integer from 1 to 10.

[0148] Very preferred groups P are selected from the group consisting of:

[0149] CH2=CW 1 -CO-O-, CH2=CW 1 -CO-, CH2=CW 2 -O-, CH2=CW 2 -、

[0150] CW 1 =CH-CO-(O) k3 -、CW 1 =CH-CO-NH-, CH2=CW 1 -CO-NH-,

[0151] (CH2=CH)2CH-OCO-, (CH2=CH-CH2)2CH-OCO-, (CH2=CH)2CH-O-,

[0152] (CH2=CH-CH2)2N-, (CH2=CH-CH2)2N-CO-, CH2=CW 1 -CO-NH-,

[0153] CH2=CH-(COO) k1 -Phe-(O) k2 -、CH2=CH-(CO) k1 -Phe-(O) k2 -, Phe-CH=CH- and W 4 W 5 W 6 Si-, where W 1 represents H, F, Cl, CN, CF3, phenyl or alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH3, W 2 and W 3 each independently of one another represents H or alkyl having 1 to 5 C atoms, in particular H, methyl, ethyl or n-propyl, W 4 , W 5 and W 6 each independently represents Cl, an oxaalkyl or oxacarbonylalkyl radical having 1 to 5 C atoms, W 7 and W 8 Each independently represents H, Cl or an alkyl group having 1 to 5 C atoms, Phe represents 1,4-phenylene, k1, k2 and k3 each independently represent 0 or 1, k3 preferably represents 1, and k4 represents an integer of 1 to 10.

[0154] Very particularly preferred radicals P are selected from the group consisting of:

[0155] CH2=CW 1-CO-O-, in particular CH2=CH-CO-O-, CH2=C(CH3)-CO-O- and CH2=CF-CO-O-, in addition CH2=CH-O-, (CH2=CH)2CH-O-CO-, (CH2=CH)2CH-O-, and

[0156] Other preferred polymerizable groups P are selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetane and epoxy groups, most preferably from acrylate and methacrylate groups.

[0157] If the spacer group Sp is different from a single bond, it is preferably of the formula Sp"-X", so that each group P-Sp- corresponds to the formula P-Sp"-X"-, where

[0158] Sp" denotes a straight-chain or branched alkylene radical having 1 to 20, preferably 1 to 12 C atoms, which is optionally mono- or polysubstituted by F, Cl, Br, I or CN, and in which, in addition, one or more non-adjacent CH2 groups are each independently substituted by -O-, -S-, -NH-, -N(R 0 )-、-Si(R 0 R 00 )-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -S-CO-, -CO-S-, -N(R 00 )-CO-O-、-O-CO-N(R 0 )-、-N(R 0 )-CO-N(R 00 )-, -CH=CH- or -C≡C- in such a way that the O and / or S atoms are not directly connected to each other,

[0159] X" means -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, -CO-N(R 0 )-、-N(R 0 )-CO-、-N(R 0 )-CO-N(R 00 )-, -OCH2-, -CH2O-, -SCH2-, -CH2S-, -CF2O-, -OCF2-, -CF2S-, -SCF2-, -CF2CH2-, -CH2CF2-, -CF2CF2-, -CH=N-, -N=CH-, -N=N-, -CH=CR 0 -、-CY 2 =CY 3-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH- or a single bond,

[0160] R 0 and R 00 each independently of one another represents H or an alkyl group having 1 to 20 C atoms, and

[0161] Y 2 and Y 3 Each independently of one another represents H, F, Cl or CN.

[0162] X" is preferably -O-, -S-, -CO-, -COO-, -OCO-, -O-COO-, -CO-NR 0 -、-NR 0 -CO-、-NR 0 -CO-NR 00 - or single key.

[0163] Typical spacer groups Sp and -Sp"-X"- are, for example, -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, -(CH2CH2O) q1 -CH2CH2-, -CH2CH2-S-CH2CH2-, -CH2CH2-NH-CH2CH2- or -(SiR 0 R 00 -O) p1 -, wherein p1 is an integer from 1 to 12, q1 is an integer from 1 to 3, and R 0 and R 00 has the meaning indicated above.

[0164] Particularly preferred groups Sp and -Sp"-X"- are -(CH2) p1 -、-(CH2) p1 -O-, -(CH2) p1 -O-CO-, -(CH2) p1 -CO-O-, -(CH2) p1 -O-CO-O-, wherein p1 and q1 have the meanings indicated above.

[0165] 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-methylimino-ethylene, 1-methylalkylene, vinylene, propenylene and butenylene.

[0166] In a preferred embodiment of the invention, the compounds of formula I and its subformulae contain a group R=Sp(P)2. According to this preferred embodiment, very preferred compounds of formula I contain a group R selected from the following formulae:

[0167] -X-alkyl-CHPP S1

[0168] -X-alkyl-CH((CH2) aa P)((CH2) bb P) S2

[0169] -XN((CH2) aa P)((CH2) bb P) S3

[0170] -X-alkyl-CHP-CH2-CH2P S4

[0171] -X-alkyl-C(CH2P)(CH2P)-C aa H 2aa+1 S5

[0172] -X-alkyl-CHP-CH2P S6

[0173] -X-alkyl-CPP-C aa H 2aa+1 S7

[0174] -X-alkyl-CHPCHP-C aa H 2aa+1 S8

[0175] wherein P is as defined in formula I,

[0176] Alkyl represents a single bond or a straight-chain or branched alkylene radical having 1 to 12 C atoms, which is unsubstituted or mono- or polysubstituted by F, Cl or CN, wherein one or more non-adjacent CH2 groups may each be replaced independently of one another by -C(R 0 )=C(R 0 )-、-C≡C-、-N(R 0)-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, wherein R 0 has the meaning as stated above.

[0177] aa and bb each independently represent 0, 1, 2, 3, 4, 5 or 6,

[0178] X has one of the meanings given for X" and is preferably O, CO, SO2, O-CO-, CO-O or a single bond.

[0179] Preferred spacer groups Sp(P)2 are selected from the group consisting of formulae S1, S2 and S3.

[0180] Very preferred spacer groups Sp(P)2 are selected from the following sub-formulae:

[0181] -CHPP S1a

[0182] -O-CHPP S1b

[0183] -CH2-CHPP S1c

[0184] -OCH2-CHPP S1d

[0185] -CH(CH2-P)(CH2-P) S2a

[0186] -OCH(CH2-P)(CH2-P) S2b

[0187] -CH2-CH(CH2-P)(CH2-P) S2c

[0188] -OCH2-CH(CH2-P)(CH2-P) S2d

[0189] -CO-NH((CH2)2P)((CH2)2P) S3a

[0190] In the compounds of formulae I and II and subformulae thereof as described above and below, P is preferably selected from vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl and epoxy, most preferably acrylate and methacrylate.

[0191] Further preferred are compounds of the formula I and subformulae thereof as described above and below, wherein all polymerizable groups P present in the compound have the same meaning and very preferably represent acrylate or methacrylate groups, most preferably methacrylate groups.

[0192] In the compounds of formula I and subformulae thereof as described above and below, R preferably represents P-Sp- or -Sp(P)2, most preferably -Sp-P.

[0193] Further preferred are compounds of formula I and subformulae thereof as described above and below, wherein Sp represents a single bond or -(CH2) p1 -、-O-(CH2) p1 、-O-CO-(CH2) p1 , or -CO-O-(CH2) p1 , wherein p1 is 2, 3, 4, 5 or 6, and if Sp is -O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , O-atom or CO-group is attached to the benzene ring respectively.

[0194] Further preferred are compounds of formula I and subformulae thereof as described above and below, wherein A 1 -(Z 1 -A 2 ) z denotes biphenyl and the compound contains two or more groups P-Sp-, then at least one group Sp present in the compound is a single bond. Further preferred are compounds of the general formula I and subformulae thereof as described above and below, wherein at least one group Sp is a single bond.

[0195] Further preferred are compounds of formula I and its subformulae as described above and below, wherein at least one group Sp is different from a single bond and is preferably selected from -(CH2) p1 -、-O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , wherein p1 is 2, 3, 4, 5 or 6, and if Sp is -O-(CH2) p1 -、-O-CO-(CH2) p1 or -CO-O-(CH2) p1 , O-atom or CO-group is attached to the benzene ring respectively.

[0196] In the compounds of formula and its subformulae, A 1 and A 2 Preferably selected from phenylene-1,4-diyl, phenylene-1,3-diyl and naphthalene-2,6-diyl, all of which are optionally substituted by one or more radicals L, L as defined in formula I 11 or P-Sp-substituted.

[0197] Preferred compounds of formula I and its subformulae are those wherein z is 1 and A1 and A 2 Those selected from phenylene-1,4-diyl and naphthalene-2,6-diyl, all of which are optionally substituted with one or more groups L, L as defined in formula I 11 or P-Sp-substituted.

[0198] Further preferred compounds of formula I and its subformulae are those wherein z is 2 and A 1 and A 2 Those selected from phenylene-1,4-diyl, phenylene-1,3-diyl and naphthalene-2,6-diyl, all of which are optionally substituted by one or more groups L, L as defined in formula I 11 or P-Sp-substituted.

[0199] A very preferred group in formula I, part of the group -A 1 -(ZA 2 ) z -Selected from the following formula

[0200]

[0201]

[0202] At least one ring is surrounded by at least one group L 11 The substituted and benzene rings are optionally further substituted with one or more groups L or P-Sp-.

[0203] Preferred compounds of formula I are selected from the following sub-formulae:

[0204]

[0205]

[0206] wherein P, Sp, R and L have the meanings given in formula I,

[0207] r1, r3 are independently 0, 1, 2 or 3,

[0208] r2 is 0, 1, 2, 3, or 4,

[0209] r4, r5 are independently 0, 1 or 2,

[0210] wherein r1+r6≥1, r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1 and at least one group L represents -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7, preferably -CH2-O-CH3, and

[0211] In formula I1, at least one group Sp is a single bond.

[0212] Preference is given to compounds of I1-I5 in which one of the two radicals R is H and the other is P-Sp.

[0213] Further preference is given to compounds of I1-I5 in which both radicals R represent H.

[0214] Further preference is given to compounds of I1 to I5 in which both radicals R represent P-Sp.

[0215] Very preferred are compounds of the formulae I1, I2 and I5.

[0216] Very preferred compounds of formula I and I1-I5 are selected from the following sub-formulae:

[0217]

[0218]

[0219]

[0220] wherein P, Sp, P(Sp)2, L have the meanings given in formula I and above, r1-r6 have the meanings given in formulas I1-I5, and at least one group L, preferably one or two, more preferably one group L represents -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7, preferably -CH2-O-CH3.

[0221] Preferred compounds of the formulae I1-I5 and I1-1 to I5-5 are those in which all radicals Sp represent single bonds.

[0222] Very preferred compounds of formula I are selected from the following sub-formulae:

[0223]

[0224]

[0225]

[0226]

[0227]

[0228]

[0229]

[0230]

[0231]

[0232]

[0233]

[0234] Where L a is -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7, preferably -CH2-O-CH3, P, Sp and Sp(P)2 have the meanings given above and below, Sp is preferably different from a single bond, and L' has one of the meanings given above and below for L, which is preferably the same as L a L' preferably represents F.

[0235] Preferred compounds of formula I and their subformulae are selected from the following preferred embodiments, including any combination thereof:

[0236] - all groups P in the compound have the same meaning,

[0237] --A 1 -(ZA 2 ) z - is selected from the group consisting of formulae A1, A2 and A5,

[0238] - The compound contains one, two or three groups L 11 ,

[0239] - the compound contains exactly two polymerizable groups (represented by the group P),

[0240] - the compound contains exactly three polymerizable groups (represented by the group P),

[0241] - P is selected from acrylate, methacrylate and oxetanyl, very preferably acrylate or methacrylate,

[0242] -P is a methacrylate group,

[0243] - all groups Sp are single bonds,

[0244] - at least one group Sp is a single bond and at least one group Sp is different from a single bond,

[0245] -When different from a single bond, Sp is -(CH2) p2 -、-(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or CO-group is connected to the benzene ring,

[0246] -Sp is a single bond or represents -(CH2) p2 -、-(CH2)p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or CO-group is connected to the benzene ring,

[0247] -Sp(P)2 is selected from the group consisting of subformulas S11-S31,

[0248] -R means P-Sp-,

[0249] -R does not represent or contain a polymerizable group,

[0250] -R does not represent or contain a polymerizable group and represents a straight-chain, branched or cyclic alkyl group having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to each other, and wherein one or more H atoms are each optionally replaced by F, Cl or L a Instead,

[0251] -L or L', when with L 11 If different, it means F, Cl or CN.

[0252] -L' is F,

[0253] -r1, r2 and r3 represent 0 or 1,

[0254] -r1, r2, r3, r4, r5 and r6 represent 0 or 1,

[0255] - one of r1 and r6 is 0 and the other is 1,

[0256] -r1 is 1, and r2 and r3 are 0,

[0257] -r3 is 1 and r1 and r2 are 0,

[0258] - one of r4 and r5 is 0 and the other is 1,

[0259] -r1 and r4 are 0 and r3 is 1,

[0260] -r1 and r3 are 0 and r4 is 1,

[0261] -r3 and r4 are 0 and r1 is 1.

[0262] Particularly preferred compounds are selected from the following:

[0263]

[0264]

[0265]

[0266]

[0267]

[0268] The self-aligning additives can be polymerized in the liquid crystal medium under similar conditions as used for RMs in the PSA process.

[0269] Suitable SA additives for inducing homeotropic alignment, in particular for SA-VA mode displays, are disclosed in, for example, US2013 / 0182202A1, US2014 / 0838581A1, US2015 / 0166890A1 and US2015 / 0252265A1.

[0270] In formula II, the group MES preferably contains a ring selected from aromatic, alicyclic and heterocyclic groups as described above, including their preferred meanings. The most preferred ring is 1,4-phenylene, which can be replaced by L as defined below 1 and -Sp-P, or is 1,4-cyclohexylene.

[0271] In formula II, the group MES is preferably a group selected from the following structures, which may be substituted by a group L 1 and any one of mono- or poly-substituted -Sp-P:

[0272]

[0273]

[0274] in

[0275] L 1 represents, in each case independently of one another, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R 0 )2, -C(=O)R 0 , optionally substituted silyl, optionally substituted aryl or cycloalkyl having 3 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 25 C atoms, wherein, in addition, one or more H atoms may each be replaced by F or Cl,

[0276] P represents a polymerizable group, and

[0277] Sp represents a spacer group or a single bond,

[0278] and the dotted line represents the polar anchoring group R aconnection point.

[0279] Preferably, the self-aligning additive for vertical alignment is selected from Formula IIa

[0280] R 1 -[A 2 -Z 2 ] m -A 1 -R a IIa

[0281] in

[0282] A 1 ,A 2 each independently of one another represents an aromatic, heteroaromatic, alicyclic or heterocyclic group, which may also contain fused rings, and which may also be replaced by a group L 1 or -Sp-P is singly or polysubstituted,

[0283] L 1 represents, in each case independently of one another, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R 0 )2, -C(=O)R 0 , optionally substituted silyl, optionally substituted aryl or cycloalkyl having 3 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 25 C atoms, wherein, in addition, one or more H atoms may each be replaced by F or Cl,

[0284] P represents a polymerizable group,

[0285] Sp represents a spacer group or a single bond,

[0286] Z 2 represents, independently of one another, a single bond, -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 ) n1 -, -CH(-Sp-P)-, -CH2CH(-Sp-P)- or -CH(-Sp-P)CH(-Sp-P)-,

[0287] n1 means 1, 2, 3 or 4,

[0288] m represents 1, 2, 3, 4, 5 or 6,

[0289] R 0 represents in each case, independently of one another, an alkyl radical having 1 to 12 C atoms,

[0290] R 00 in each case independently of one another is H or alkyl having 1 to 12 C atoms,

[0291] R 1 independently of one another denotes H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein in addition one or more non-adjacent CH2 groups can each be replaced by -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, and wherein in addition one or more H atoms can each be replaced by F or Cl, or denotes the group -Sp-P, and

[0292] R a As defined above, preferably refers to a polar anchoring group which is further characterized by having at least one selected from -OH, -NH2, NHR 11 , C(O)OH and –CHO, where R 11 represents an alkyl group having 1 to 12 C atoms,

[0293] In a further preferred embodiment, the liquid-crystalline media or polymer-stabilized SA-VA displays according to the invention contain one or more self-aligning additives selected from Table G below.

[0294] Anchoring group R of self-aligning additive a More preferably defined as follows:

[0295] R a is an anchoring group having the formula

[0296]

[0297] in

[0298] p means 1 or 2,

[0299] q means 2 or 3,

[0300] B represents a substituted or unsubstituted ring system or a condensed ring system, preferably selected from benzene, pyridine, cyclohexane, dimethicone, an alkane or tetrahydropyran ring system,

[0301] Y independently represents -O-, -S-, -C(O)-, -C(O)O-, -OC(O)-, -NR 11 - or single key,

[0302] o means 0 or 1,

[0303] X 1 Each independently represents H, alkyl, fluoroalkyl, OH, NH2, NHR 11 NR 11 2. OR 11 , C(O)OH or -CHO, wherein at least one group X 1 It represents a compound selected from -OH, -NH2, NHR 11 , C(O)OH and -CHO groups,

[0304] R 11 represents an alkyl group having 1 to 12 C atoms,

[0305] Sp a ,Sp c ,Sp d each independently of one another represents a spacer group or a single bond, and

[0306] Sp b represents a trivalent or tetravalent group, preferably CH, N or C.

[0307] Formulae II and IIa optionally include polymerizable compounds. In the present disclosure, "a medium comprising a compound of formula II / IIa" refers to a medium comprising a compound of formula II / IIa, and alternatively refers to a medium comprising the compound in its polymerized form.

[0308] In the case where one or more compounds of the formula II are substituted with one or more polymerizable groups (—Sp—P), the liquid-crystalline media according to the invention comprise

[0309] a polymerizable component A) comprising, preferably consisting of, polymerizable compounds, at least one of which is a compound of formula I and at least one of which is a compound of formula II,

[0310] - The liquid-crystalline component B), hereinafter also referred to as "LC host mixture", comprises, preferably consists of, one or more mesogenic or liquid-crystalline compounds.

[0311] In the compounds of formula IIa and its subformulae, Z 1 and Z 2 Preferably, Z represents a single bond, -C2H4-, -CF2O- or -CH2O-. 1 and Z 2Each independently represents a single bond.

[0312] In the compounds of the formula IIa, the radical L independently in each case preferably represents F or alkyl, preferably CH3, C2H5 or C3H7.

[0313] Preferred compounds of formula IIa are illustrated by the following sub-formulae II-A to II-D

[0314]

[0315] Where R 1 ,R a ,A 2 ,Z 2 ,Sp,P and L 1 has the meaning as defined above for Formula IIa,

[0316] m is independently 1, 2 or 3, and

[0317] r1 is independently 0, 1, 2, 3, or 4, preferably 0, 1 or 2.

[0318] In the compounds of formula II-A to II-D, L 1 Preferably it represents F or alkyl, preferably CH3, C2H5 or C3H7.

[0319] In a preferred embodiment, r1 represents 0.

[0320] The polymerizable group P of formula II, IIa, II-A to II-D is preferably a methacrylate group, an acrylate group or other substituted acrylate groups, most preferably a methacrylate group.

[0321] In the above and below formulae IIa or II-A to II-D and subformulae thereof, Z 1 Preferably independently represents a single bond or -CH2CH2-, and very particularly a single bond.

[0322] R a Preferred representation

[0323]

[0324] Where p = 1, 2, 3, 4, 5 or 6,

[0325] x = 1 or 0, preferably 1, and

[0326] R 22 is H, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, or -CH2CH2-tert-butyl,

[0327] In particular

[0328] -O(CH2)2-OH, -O(CH2)3-OH,

[0329]

[0330]

[0331] Where R 22 is H, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, or -CH2CH2-tert-butyl,

[0332] or

[0333]

[0334] In Formula IIa and subformulas of Formula IIa, R 1 Preferably, it represents a straight-chain alkyl group or a branched-chain alkyl group having 1 to 8 C atoms, preferably a straight-chain alkyl group. 1 More preferably, it represents CH3, C2H5, n-C3H7, n-C4H9, n-C5H 11 ,n-C6H 13 Or CH2CH(C2H5)C4H9. 1 It may further represent alkenyloxy, in particular OCH2CH=CH2, OCH2CH=CHCH3, OCH2CH=CHC2H5 or alkoxy, in particular OC2H5, OC3H7, OC4H9, OC5H 11 and OC6H 13 . R 1 Particularly preferably, it represents a straight chain alkyl group, preferably C5H 11 .

[0335] In a preferred embodiment of the present invention, the liquid crystal medium comprises a compound of formula II which is polymerizable. Preference is given to combinations of the following polymerizable additives of formula I and II:

[0336] - a liquid-crystalline medium comprising one or more compounds of the formula II-1 and one or more compounds of the formula II;

[0337] - a liquid-crystalline medium comprising one or more compounds of the formula II-1-1 and one or more compounds of the formula II-A or II-B;

[0338] - a liquid-crystalline medium comprising one or more compounds of the formula I1-1-1 and one or more compounds of the formula II-B; or

[0339] - contains one or more compounds of the formula

[0340]

[0341] and one or more compounds of the formula II-A or II-B.

[0342] The compounds of the formulae I and II and their subformulae and the intermediates can be prepared analogously to the methods known to the person skilled in the art and described in standard texts of organic chemistry, for example Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Thieme-Verlag, Stuttgart.

[0343] For example, the compound of formula I can be synthesized by esterification or etherification of an intermediate, wherein both Sp-P groups at both ends represent OH, using the corresponding acid, acid derivative or halogenated compound containing a polymerizable group P.

[0344] For example, acrylates or methacrylates can be prepared by esterification of 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 or triethylamine, and 4-(N,N-dimethylamino)pyridine (DMAP). Alternatively, esters can be prepared by esterification of alcohols with (meth)acrylic acid in the presence of a dehydrating agent, such as dicyclohexylcarbodiimide (DCC), N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) or N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and DMAP according to Steglich.

[0345] Other suitable methods are shown in the Examples.

[0346] To produce PSA displays, the polymerizable compounds contained in the liquid-crystalline medium are polymerized or crosslinked (if one compound contains two or more polymerizable groups) by in situ polymerization in the liquid-crystalline medium between the substrates of the LC display, optionally while applying a voltage to the electrodes.

[0347] The structure of the PSA display according to the invention corresponds to the usual geometries for PSA displays, as described in the prior art cited at the outset. Geometries without protrusions are preferred, in particular those in which the electrode on the color filter side is also unstructured and only the electrode on the TFT side has grooves. Particularly suitable and preferred electrode structures for PS-VA displays are described, for example, in US 2006 / 0066793 A1.

[0348] Preferred LC displays of the PSA type according to the invention comprise:

[0349] a first substrate, comprising a pixel electrode defining a pixel area, the pixel electrode being connected to a switching element disposed in each pixel area and optionally comprising a micro-slit pattern, and optionally comprising a first alignment layer disposed on the pixel electrode,

[0350] - a second electrode, comprising a common electrode layer, which may be disposed over the entire portion of the second substrate facing the first substrate, and optionally a second alignment layer,

[0351] - an LC layer disposed between the first and the second substrate, which comprises the liquid-crystalline medium according to the invention as described above and below, wherein the polymerisable component (A) can also be polymerised.

[0352] The self-aligning additives contained in the medium induce homeotropic alignment (perpendicular to the surface) or tilted homeotropic alignment of the LC layer.

[0353] The LC layer with the liquid crystal medium can be deposited between the substrates of the display by methods conventionally used by display manufacturers, for example by the so-called one drop filling (ODF) method. The polymerizable components of the liquid crystal medium are subsequently polymerized, for example by UV photopolymerization. The polymerization can be carried out in one step or in two or more steps.

[0354] A PSA display may include further elements such as colour filters, a black matrix, a passivation layer, an optical retardation layer, transistor elements for addressing individual pixels etc., all of which are well known to those skilled in the art.

[0355] Those skilled in the art can design the electrode structure according to each display type. For example, for a PS-VA display, the multi-domain orientation of the LC molecules can be induced by providing electrodes with slits and / or bumps or protrusions to produce two, four or more different tilted alignment directions.

[0356] After polymerization, the polymerizable compound forms a cross-linked polymer, which causes a certain pre-tilt of the LC molecules in the liquid crystal medium. Without wishing to be bound by a particular theory, it is believed that at least a portion of the cross-linked polymer (which is formed by the polymerizable compound) will phase separate or precipitate from the liquid crystal medium and form a polymer layer on the substrate or electrode. Microscopic measurement data (such as SEM and AFM) have confirmed that at least a portion of the formed polymer accumulates at the LC / substrate interface.

[0357] It is also possible to firstly polymerize in a first step, optionally with simultaneous application of a voltage, in order to produce a pretilt angle, and then, in a second polymerization step without application of a voltage, polymerize or crosslink the unreacted compounds of the first step ("final curing").

[0358] Suitable and preferred polymerisation methods are, for example, thermal polymerisation or photopolymerisation, preferably photopolymerisation, in particular UV-induced photopolymerisation, which can be achieved by exposing the polymerisable compound to UV radiation.

[0359] Optionally, one or more polymerization initiators are added to the liquid crystal medium. Suitable conditions for polymerization and suitable types and amounts of initiators are known to the person skilled in the art and are described in the literature. Suitable for free-radical polymerization are, for example, commercially available photoinitiators or (Ciba AG). If a polymerization initiator is used, its proportion is preferably from 0.001 to 5% by weight, particularly preferably from 0.001 to 1% by weight.

[0360] The polymerizable compounds according to the invention are also suitable for polymerization without the use of initiators, which is accompanied by considerable advantages, for example, lower raw material costs and in particular less contamination of the liquid crystal medium by possible residual amounts of initiators or their degradation products. The polymerization can therefore also be carried out without the addition of initiators. In a preferred embodiment, the liquid crystal medium therefore does not contain a polymerization initiator.

[0361] The liquid crystal medium may also contain one or more stabilizers to prevent undesired spontaneous polymerization of the RM, for example during storage or transportation. Suitable types and amounts of stabilizers are known to the person skilled in the art and are described in the literature. Particularly suitable are stabilizers such as those from Commercially available stabilizers of the TUNA series (Ciba AG), for example 1076. If a stabilizer is used, its proportion is preferably 10 to 500,000 ppm, particularly preferably 50 to 50,000 ppm, based on the total amount of RM or polymerizable component (component A).

[0362] The polymerizable compounds of the formula I do show good UV absorption, in particular in a process for producing a PSA display, and are therefore particularly suitable for use in such a process, which comprises one or more of the following features:

[0363] - the polymerizable medium is exposed to UV light in a two-step process in a display, comprising a first UV exposure step ("UV-1 step") to produce the tilt angle, and a second UV exposure step ("UV-2 step") to complete the polymerization,

[0364] The polymerizable medium is exposed in a display to UV light generated by energy-saving UV lamps (also called "green UV lamps"). These lamps are characterized by relatively low intensities in their absorption spectrum of 300-380 nm (1 / 100-1 / 10 of conventional UV1 lamps), and are preferably used in the UV2 step, but are optionally also used in the UV1 step when avoiding high intensities is necessary for the process.

[0365] The polymerizable medium is exposed in the display to UV light generated by a UV lamp having a radiation spectrum shifted to longer wavelengths, preferably 340 nm or more, in order to avoid exposure to short UV light in the PS-VA process.

[0366] Both using lower intensity and shifting the UV to longer wavelengths protects the organic layers from damage that might be caused by UV light.

[0367] A preferred embodiment of the present invention relates to a method for producing a PSA display as described above and below, comprising one or more of the following features:

[0368] - the polymerizable liquid crystal medium is exposed to UV light in a two-step process comprising a first UV exposure step ("UV-1 step") to produce the tilt angle, and a second UV exposure step ("UV-2 step") to complete the polymerization,

[0369] - the polymerizable liquid crystal medium is exposed to a 300-380 nm wavelength range with a power of 0.5 mW / cm 2 -10mW / cm 2 UV light generated by a UV lamp of a high intensity is preferably used in the UV2 step and is optionally also used in the UV1 step,

[0370] - the polymerizable liquid-crystalline medium is exposed to UV light having a wavelength of 340 nm or more, and preferably 400 nm or less.

[0371] This preferred method can be performed, for example, by using a desired UV lamp or by using a bandpass filter and / or a cutoff filter, which is substantially transparent to UV light of the respective desired wavelength and substantially blocks light of the respective undesired wavelength. For example, when the radiation requires UV light of a wavelength λ of 300-400nm, the UV exposure can be performed using a wide bandpass filter that is substantially transparent to a wavelength of 300nm<λ<400nm. When the radiation requires UV light of a wavelength λ greater than 340nm, the UV exposure can be performed using a cutoff filter that is substantially transparent to a wavelength of λ>340nm.

[0372] "Substantially transparent" means that the filter transmits a majority, preferably at least 50%, of the intensity of incident light of a desired wavelength. "Substantially blocking" means that the filter does not transmit a majority, preferably at least 50% of the intensity of incident light of an undesired wavelength. "Desired (undesired) wavelength" means, for example, a wavelength within (outside) a given λ range in the case of a bandpass filter, and a wavelength greater (less than) a given λ value in the case of a cutoff filter.

[0373] This preferred method enables the manufacture of displays by using longer UV wavelengths, thereby reducing or even avoiding the dangerous and damaging effects of the short UV light component.

[0374] Depending on the production process conditions, the UV radiation energy is usually 6-100J / cm 2 .

[0375] Preferably, the liquid crystal medium according to the present invention consists essentially of a polymerizable component A), and one or more polymerizable compounds of formula II, and an LC component B) or an LC host mixture as described above and below. However, the liquid crystal medium may additionally comprise one or more other components or additives, preferably selected from such a list including, but not limited to, comonomers, chiral dopants, polymerization initiators, inhibitors, stabilizers, surfactants, wetting agents, lubricants, dispersants, hydrophobic agents, binders, spreading agents, flow improvers, defoamers, deaerators, diluents, reactive diluents, auxiliaries, colorants, dyes, pigments and nanoparticles.

[0376] LC media which comprise one, two or three polymerisable compounds of the formula I are particularly preferred.

[0377] Preference is further given to LC media in which the polymerisable component A) comprises exclusively polymerisable compounds of the formula I.

[0378] Preference is further given to LC media in which the liquid-crystalline component B) or the LC host mixture has a nematic liquid-crystalline phase and preferably no chiral liquid-crystalline phase.

[0379] The LC component B), or the LC host mixture, is preferably a nematic LC mixture.

[0380] Further preference is given to achiral compounds of the formula I and LC media in which the compounds of component A and / or B are selected exclusively from achiral compounds.

[0381] Preferably, the proportion of the polymerizable component A) in the liquid-crystalline medium is from >0.3 to <5%, very preferably from >0.4 to <2%, most preferably from 0.5 to 2.5%.

[0382] Preferably, the proportion of compounds of the formula I in the liquid-crystalline medium is from >0 to <5%, very preferably from >0 to <1% and most preferably from 0.01 to 0.5%.

[0383] Preferably, the proportion of compounds of the formula II in the liquid-crystalline medium is from >0.1 to <5%, very preferably from >0.2 to <3%, most preferably from 0.2 to 1.5%.

[0384] Preferably, the proportion of LC component B) in the liquid-crystalline medium is from 95 to <100%, very preferably from 99 to <100%.

[0385] In a further preferred embodiment, the polymerizable component A) comprises, in addition to the compounds of the formula I and optionally the formula II, one or more further polymerizable compounds ("comonomers"), preferably selected from RMs.

[0386] Suitable and preferred mesogenic comonomers are selected from the following formula:

[0387]

[0388]

[0389]

[0390]

[0391]

[0392] The various groups have the following meanings:

[0393] P 1 ,P 2 and P 3 each independently of one another represents an acrylate or methacrylate group,

[0394] Sp 1 ,Sp 2 and Sp 3 each independently of one another represents a single bond or a spacer group having one of the meanings given above and below for Sp, and particularly preferably represents -(CH2) p1 -,-(CH2) p1 -O-,-(CH2) p1 -CO-O-,-(CH2) p1 -O-CO- or -(CH2) p1 -O-CO-O-, wherein p1 is an integer from 1 to 12, wherein in addition, the group P 1 -Sp 1 -,P 1 -Sp 2 - and P 3 -Sp 3 -One or more of which can represent R aa , the premise is that there exists P 1 -Sp 1 -,P 2 -Sp 2 and P 3 -Sp 3 - at least one group is different from R aa ,

[0395] R aarepresents H, F, Cl, CN or a straight-chain or branched alkyl radical having 1 to 25 C atoms, wherein in addition, one or more non-adjacent CH2 groups may each be replaced independently of one another by C(R 0 )=C(R 00 )-,-C≡C-,-N(R 0 )-, -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O and / or S atoms are not directly connected to each other, and wherein in addition, one or more H atoms may be replaced by F, Cl, CN or P 1 -Sp 1 - is replaced by, particularly preferably, a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms, where alkenyl and alkynyl have at least two C atoms and branched radicals have at least three C atoms,

[0396] R 0 ,R 00 each independently of one another and identically or differently from one another represents H or an alkyl radical having 1 to 12 C atoms,

[0397] R y and R z each independently represents H, F, CH3 or CF3,

[0398] X 1 ,X 2 and X 3 each independently represents -CO-O-, -O-CO- or a single bond,

[0399] Z 1 Indicates -O-, -CO-, -C(R y R z )- or -CF2CF2-,

[0400] Z 2 and Z 3 Each independently represents -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CF2O-, -OCF2- or (CH2) n -, where n is 2, 3 or 4,

[0401] L, on each occurrence, identically or differently, represents F, Cl, CN or a straight-chain or branched, optionally mono- or polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy radical having 1 to 12 C atoms, preferably F,

[0402] L' and L" each independently represent H, F or Cl,

[0403] k represents 0 or 1,

[0404] r represents 0, 1, 2, 3 or 4,

[0405] s represents 0, 1, 2, or 3,

[0406] t represents 0, 1 or 2,

[0407] x represents 0 or 1.

[0408] Particularly preferred are compounds of formulae M2, M13, M17, M22, M23, M24, M30, M31 and M32.

[0409] Further preference is given to trireactive compounds M15 to M30, in particular M17, M18, M19, M22, M23, M24, M25, M26, M30, M31 and M32.

[0410] In the compounds of formulae M1 to M32, the group

[0411] Preferably

[0412] in which L has, identically or differently on each occurrence, one of the meanings given above and below and is preferably F, Cl, CN, NO2, CH3, C2H5, C(CH3)3, CH(CH3)2, CH2CH(CH3)C2H5, OCH3, OC2H5, COCH3, COC2H5, COOCH3, COOC2H5, CF3, OCF3, OCHF2, OC2F5 or P-Sp-, very preferably F, Cl, CN, CH3, C2H5, OCH3, COCH3, OCF3 or P-Sp-, more preferably F, Cl, CH3, OCH3, COCH3 or OCF3 and in particular F or CH3.

[0413] In addition to the polymerisable compounds described above, the LC medium for use in the LC display according to the invention comprises an LC mixture ("host mixture") comprising one or more, preferably two or more, LC compounds selected from non-polymerisable low molecular weight compounds. These LC compounds are selected such that they are stable and / or unreactive towards polymerisation reactions under the polymerisation conditions applicable to the polymerisable compounds.

[0414] In principle, any LC mixture suitable for conventional displays is suitable as host mixture. Suitable LC mixtures are known to the person skilled in the art and are described in the literature, for example mixtures in VA displays in EP 1 378 557 A1.

[0415] In a preferred embodiment, the liquid crystal medium comprises an LC component B) or an LC host mixture based on a compound with negative dielectric anisotropy. The LC medium is particularly suitable for PS-VA and PS-UB-FFS displays. Particularly preferred embodiments of the liquid crystal medium are those of the following sections a) to z):

[0416] a) Liquid-crystalline media comprising LC component B) or LC host mixtures of one or more compounds of the formulae CY and PY:

[0417]

[0418] in

[0419] a means 1 or 2,

[0420] b represents 0 or 1,

[0421] express

[0422] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0423] Z x and Z y Each independently represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond,

[0424] L 1-4 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0425] Preferably, L 1 and L 2 Both represent F or L 1 and L 2 One of them represents F and the other represents Cl, or L 3 and L 4 Both represent F or L 3 and L 4 One represents F and the other represents Cl.

[0426] The compound of formula CY is preferably selected from the following sub-formulae:

[0427]

[0428]

[0429]

[0430]

[0431]

[0432] Where a represents 1 or 2, alkyl and alkyl * each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical 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-.

[0433] The compound of formula PY is preferably selected from the following sub-formulae:

[0434]

[0435]

[0436]

[0437] Among them, alkyl and alkyl * each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical 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-.

[0438] b) a liquid-crystalline medium comprising an LC component B) or an LC host mixture of one or more compounds of the following formulae:

[0439]

[0440] The various groups have the following meanings:

[0441] express express

[0442] R 3 and R 4 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another,

[0443] Z y It represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond.

[0444] The compounds of formula ZK are preferably selected from the following sub-formulae:

[0445]

[0446]

[0447] Among them, alkyl and alkyl * each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical having 2 to 6 C atoms. 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-.

[0448] The compounds of formula ZK1 are particularly preferred.

[0449] Particularly preferred compounds of formula ZK are selected from the following sub-formulae:

[0450]

[0451]

[0452] Among them, propyl, butyl and pentyl are straight-chain groups.

[0453] The compounds of formula ZK1a and ZK3b are most preferred.

[0454] c) LC components B) or LC host mixtures which additionally comprise one or more compounds of the following formulae:

[0455]

[0456] where the individual radicals have the following meanings on each occurrence, identically or differently:

[0457] R 5 and R 6 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0458] express express and e means 1 or 2.

[0459] The compound of formula DK is preferably selected from the following sub-formulae:

[0460]

[0461]

[0462] Among them, alkyl and alkyl * each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl represents a straight-chain alkenyl radical having 2 to 6 C atoms. 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-.

[0463] d) Liquid-crystalline media which additionally comprise an LC component B) or an LC host mixture of one or more compounds of the following formulae:

[0464]

[0465] The various groups have the following meanings:

[0466] express

[0467] wherein at least one ring F is different from cyclohexylene,

[0468] f means 1 or 2,

[0469] R 1 and R 2each independently of one another represents an alkyl group having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another,

[0470] Z x represents -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CH2O- or a single bond, preferably a single bond,

[0471] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0472] Preferably, the group L 1 and L 2 All represent F or group L 1 and L 2 One represents F and the other represents Cl.

[0473] The compound of formula LY is preferably selected from the following sub-formulae:

[0474]

[0475]

[0476]

[0477]

[0478] Where R 1 has the meanings given above, alkyl represents a straight-chain alkyl group having 1-6 C atoms, (O) represents an oxygen atom or a single bond, and v represents an integer of 1-6. 1 Preferably it represents a straight-chain alkyl radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, in particular CH3, C2H5, n-C3H7, n-C4H9, n-C5H 11 , 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-.

[0479] e) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures selected from the group consisting of compounds of the following formulae:

[0480]

[0481]

[0482] Where alkyl represents C 1-6 -alkyl, L x represents H or F, and X represents F, Cl, OCF3, OCHF2 or OCH=CF2. Particularly preferred are compounds of formula G1, wherein X represents F.

[0483] f) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures selected from the group consisting of compounds of the following formulae:

[0484]

[0485]

[0486]

[0487] Where R 5 With the above for R 1 One of the meanings, alkyl means C 1-6 -alkyl, d represents 0 or 1, and z and m each independently represent an integer of 1 to 6. In these compounds, R 5 C is particularly preferred 1-6 -alkyl or -alkoxy or C 2-6 -alkenyl, d is preferably 1. The liquid-crystalline media according to the invention preferably comprise one or more compounds of the formulae indicated above in an amount of ≥5% by weight.

[0488] g) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures selected from biphenyl compounds of the following formulae:

[0489]

[0490] Among them, alkyl and alkyl * each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, and alkenyl and alkenyl * Each independently of one another represents a straight-chain alkenyl radical having 2 to 6 C atoms. * Preferably it 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-.

[0491] The proportion of biphenyls of the formulae B1 to B3 in the LC host mixture is preferably at least 3% by weight, in particular ≥5% by weight.

[0492] Compounds of formula B2 are particularly preferred.

[0493] The compounds of formulae B1 to B3 are preferably selected from the following sub-formulae:

[0494]

[0495] Among them, alkyl * denotes an alkyl radical having 1 to 6 C atoms. The medium according to the invention particularly preferably comprises one or more compounds of the formula B1a and / or B2c.

[0496] h) a liquid-crystalline medium which additionally comprises the LC component B) or the LC host mixture of one or more terphenyl compounds of the following formulae:

[0497]

[0498] Where R 5 and R 6 Each independently has one of the above meanings, and

[0499]

[0500] Each independently expresses

[0501]

[0502] Where L 5 represents F or Cl, preferably F, and L 6 represents F, Cl, OCF3, CF3, CH3, CH2F or CHF2, preferably F.

[0503] The compound of formula T is preferably selected from the following sub-formulae:

[0504]

[0505]

[0506]

[0507] wherein R represents a straight chain alkyl or alkoxy group having 1 to 7 C atoms, R * R represents a straight-chain alkenyl group having 2 to 7 C atoms, (O) represents an oxygen atom or a single bond, and m represents an integer of 1 to 6. *Preferably it 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-.

[0508] R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentoxy.

[0509] The LC host mixture according to the invention preferably comprises the terphenyl of the formula T and preferred subformulae thereof in an amount of 0.5 to 30% by weight, in particular 1 to 20% by weight.

[0510] Particular preference is given to compounds of the formulae T1, T2, T3 and T21. In these compounds, R preferably represents alkyl, and also alkoxy, each having 1 to 5 C atoms.

[0511] Preference is given to using terphenyls in the mixtures according to the invention if the Δn value of the mixture is ≥ 0.1. Preferred LC media comprise 2 to 20% by weight of one or more terphenyl compounds of the formula T, preferably selected from compounds T1 to T22.

[0512] i) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures selected from quaterphenyl compounds of the following formulae:

[0513]

[0514] in

[0515] R Q is alkyl, alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of which are optionally fluorinated,

[0516] X Q is F, Cl, a haloalkyl or alkoxy group having 1 to 6 C atoms, or a haloalkenyl or alkenyloxy group having 2 to 6 C atoms,

[0517] L Q1 To L Q6 are independently H or F, wherein at least one L Q1 To L Q6 For F.

[0518] Preferred compounds of formula Q are those wherein R Q Those which represent straight-chain alkyl radicals having 2 to 6 C atoms, very preferably ethyl, n-propyl or n-butyl.

[0519] Preferred compounds of formula Q are those wherein L Q3 and LQ4 Those wherein L is F. Further preferred compounds of formula Q are those wherein L Q3 , L Q4 , and L Q1 and L Q2 Those in which one or both are F.

[0520] Preferred compounds of formula Q are those wherein X Q Those representing F or OCF3, F being very preferred.

[0521] The compound of formula Q is preferably selected from the following sub-formula

[0522]

[0523]

[0524] Where R Q has one of the meanings given above and below for the formula Q or one of its preferred meanings and is preferably ethyl, n-propyl or n-butyl.

[0525] Particularly preferred are compounds of formula Q1, especially those wherein R Q Those which are n-propyl.

[0526] Preferably, the proportion of the compound of the formula Q in the LC host mixture is >0 to ≤5% by weight, very preferably 0.1-2% by weight, most preferably 0.2-1.5% by weight.

[0527] Preferably the LC host mixture contains 1 to 5, preferably 1 or 2, compounds of formula Q.

[0528] The addition of quaterphenyl compounds of formula Q to the LC host mixture can reduce the ODF color difference while maintaining high UV absorption, allowing fast and complete polymerization, allowing for strong and rapid tilt angles, and increasing the UV stability of the liquid crystal medium.

[0529] In addition, adding a compound of formula Q with positive dielectric anisotropy to a liquid crystal medium with negative dielectric anisotropy can better control the dielectric constants ε|| and ε ⊥ , in particular, the ability to achieve a high dielectric constant ε while keeping the dielectric anisotropy Δε constant || value, thereby reducing the kickback voltage and image sticking.

[0530] k) LC component B) or LC host mixture which additionally comprises one or more compounds of the formula C:

[0531]

[0532] in

[0533] R Crepresents an alkyl, alkoxy, oxaalkyl or alkoxyalkyl radical having 1 to 9 C atoms, or an alkenyl or alkenyloxy radical having 2 to 9 C atoms, all of which are optionally fluorinated,

[0534] X C represents F, Cl, a haloalkyl or alkoxy group having 1 to 6 C atoms, or a haloalkenyl or alkenyloxy group having 2 to 6 C atoms,

[0535] L C1 ,L C2 represents H or F independently of each other, where L C1 and L C2 At least one of them is F.

[0536] Preferred compounds of formula C are those wherein R C Those which represent straight-chain alkyl radicals having 2 to 6 C atoms, very preferably ethyl, n-propyl or n-butyl.

[0537] Preferred compounds of formula C are those wherein L C1 and L C2 Those for F.

[0538] Preferred compounds of formula C are those wherein X C Those representing F or OCF3, F being very preferred.

[0539] Preferred compounds of formula C are selected from the following

[0540]

[0541] Where R C has one of the meanings given above and below for the formula C or one of its preferred meanings and is preferably ethyl, n-propyl or n-butyl, very preferably n-propyl.

[0542] Preferably, the proportion of the compound of the formula C in the LC host mixture is >0 to ≤10% by weight, very preferably 0.1 to 8% by weight, most preferably 0.2 to 5% by weight.

[0543] Preferably the LC host mixture contains 1 to 5, preferably 1, 2 or 3 compounds of formula C.

[0544] Adding a compound of formula C with positive dielectric anisotropy to a liquid crystal medium with negative dielectric anisotropy can better control the dielectric constant ε || and ε ⊥ , in particular, the ability to achieve a high dielectric constant ε while keeping the dielectric anisotropy Δε constant || The value of formula C can reduce the recoil voltage and reduce image viscosity. In addition, the addition of the compound of formula C can reduce the viscosity and response time of the liquid crystal medium.

[0545] 1) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures selected from the group consisting of compounds of the following formulae:

[0546]

[0547]

[0548] Where R 1 and R 2 has the meanings given above and preferably each independently of one another denotes straight-chain alkyl having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

[0549] Preferred media comprise one or more compounds selected from the group consisting of formulae O1, O3 and O4.

[0550] m) a liquid-crystalline medium which additionally comprises an LC component B) or an LC host mixture of one or more compounds of the following formulae:

[0551]

[0552] in

[0553] express

[0554]

[0555] R 9 represents H, CH3, C2H5 or n-C3H7, (F) represents an optional fluorine substituent, and q represents 1, 2 or 3, and R 7 With respect to R 1 Within this meaning, preferred amounts are >3% by weight, in particular ≥5% by weight and very particularly preferably 5 to 30% by weight.

[0556] Particularly preferred compounds of formula FI are selected from the following sub-formulae:

[0557]

[0558]

[0559] Where R 7 Preferably represents a straight chain alkyl group, and R 9 represents CH3, C2H5 or n-C3H7. Particularly preferred are compounds of formula FI1, FI2 and FI3.

[0560] n) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures selected from the group consisting of compounds of the following formulae:

[0561]

[0562] Where R 8 With respect to R 1 The above meanings and alkyl represent straight-chain alkyl radicals having 1 to 6 C atoms.

[0563] o) a liquid-crystalline medium which additionally comprises one or more compounds containing tetrahydronaphthyl or naphthalene units, for example LC component B) or an LC host mixture selected from the group consisting of compounds of the following formulae:

[0564]

[0565]

[0566]

[0567] in

[0568] R 10 and R 11 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms, and

[0569] R 10 and R 11 preferably represents a straight-chain alkyl or alkoxy radical having 1 to 6 C atoms or a straight-chain alkenyl radical having 2 to 6 C atoms, and

[0570] Z 1 and Z 2 Each independently represents -C2H4-, -CH=CH-, -(CH2)4-, -(CH2)3O-, -O(CH2)3-, -CH=CH-CH2CH2-, -CH2CH2CH=CH-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CF=CH-, -CH=CF-, -CH2- or a single bond.

[0571] p) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures of difluorodibenzochromans and / or chromans of the following formulae:

[0572]

[0573] in

[0574] R 11 and R 12 Each independently has the above for R 11 One of the meanings,

[0575] Ring M is trans-1,4-cyclohexylene or 1,4-phenylene,

[0576] Z m is -C2H4-, -CH2O-, -OCH2-, -CO-O- or -O-CO-,

[0577] c is 0, 1, or 2,

[0578] Preferred amounts are 3-20% by weight, in particular 3-15% by weight.

[0579] Particularly preferred compounds of formula BC, CR and RC are selected from the following sub-formulae:

[0580]

[0581]

[0582]

[0583] Among them, alkyl and alkyl * each independently represents a straight-chain alkyl group having 1 to 6 C atoms, (O) represents an oxygen atom or a single bond, c is 1 or 2, and alkenyl and alkenyl * Each independently of one another represents a straight-chain alkenyl radical having 2 to 6 C atoms. * Preferably it 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-.

[0584] Very particular preference is given to LC host mixtures which comprise one, two or three compounds of the formula BC-2.

[0585] q) a liquid-crystalline medium which additionally comprises one or more LC components B) or LC host mixtures of the following formulae:

[0586]

[0587] Where R 11 and R 12 Each independently has the above for R 11 One of the meanings, b represents 0 or 1, L represents F, and r represents 1, 2 or 3.

[0588] Particularly preferred compounds of formula PH and BF are selected from the following sub-formulae:

[0589]

[0590]

[0591] wherein R and R' each independently represent a straight-chain alkyl or alkoxy group having 1 to 7 C atoms.

[0592] r) a liquid-crystalline medium which additionally comprises one or more LC components B) or a LC host mixture of monocyclic compounds of the formula

[0593]

[0594] in

[0595] R 1 and R 2 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -OCO- or -COO- in such a way that the O atoms are not directly connected to one another, preferably an alkyl radical or alkoxy radical having 1 to 6 C atoms,

[0596] L 1 and L 2 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

[0597] Preferably, L 1 and L 2 Both represent F or L 1 and L 2 One of them represents F and the other represents Cl,

[0598] The compound of formula Y is preferably selected from the following sub-formulae:

[0599]

[0600]

[0601] Among them, Alkyl and Alkyl * Each independently of one another represents a straight-chain alkyl radical having 1 to 6 C atoms, Alkoxy represents a straight-chain alkoxy radical having 1 to 6 C atoms, Alkenyl and Alkenyl * Each independently of one another represents a straight-chain alkenyl group having 2 to 6 C atoms, and O represents an oxygen atom or a single bond. *Preferably it 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-.

[0602] Particularly preferred compounds of formula Y are selected from the following sub-formulae:

[0603]

[0604] Alkoxy preferably denotes straight-chain alkoxy having 3, 4 or 5 C atoms.

[0605] s) Apart from the polymerisable compounds as described above and below, the liquid-crystalline medium comprises no compounds which contain terminal vinyloxy groups (—O—CH═CH 2 ).

[0606] t) a liquid-crystalline medium comprising LC component B) or an LC host mixture of 1 to 8, preferably 1 to 5, compounds of the formula CY1, CY2, PY1 and / or PY2. The proportion of these compounds in the entire LC host mixture is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%.

[0607] u) a liquid-crystalline medium comprising LC component B) or an LC host mixture of 1 to 8, preferably 1 to 5, compounds of the formula CY9, CY10, PY9 and / or PY10. The proportion of these compounds in the entire LC host mixture is preferably 5 to 60%, particularly preferably 10 to 35%. The content of these individual compounds is preferably in each case 2 to 20%.

[0608] v) a LC component B) or a LC host mixture comprising 1 to 10, preferably 1 to 8, compounds of the formula ZK, in particular compounds of the formula ZK1, ZK2 and / or ZK3. The proportion of these compounds in the entire LC host mixture is preferably 3 to 25%, particularly preferably 5 to 45%. The content of these individual compounds is preferably in each case 2 to 25%.

[0609] w) Liquid-crystalline media in which the proportion of compounds of the formulae CY, PY and ZK in the overall LC host mixture is greater than 70%, preferably greater than 80%.

[0610] x) a liquid-crystalline medium comprising one or more, preferably 1 to 5, LC component B) or an LC host mixture selected from compounds of the formulae PY1 to PY8, very preferably compounds of the formula PY2. The proportion of these compounds in the entire LC host mixture is preferably 1 to 30%, particularly preferably 2 to 20%. The content of these individual compounds is preferably in each case 1 to 20%.

[0611] y) LC component B) or LC host mixture comprising one or more, preferably 1, 2 or 3, compounds of the formulae T1, T2 and T5, very preferably compounds of the formula T2. The content of these compounds in the overall LC host mixture is preferably 1-20%.

[0612] z) a liquid crystal medium in which the LC host mixture contains one or more compounds selected from the group consisting of compounds of formulae CY and PY, one or more compounds selected from the group consisting of compounds of formulae ZK, and one or more compounds selected from the group consisting of compounds of formulae T and Q.

[0613] The combination of the compounds of the above preferred embodiments with the above polymeric compounds achieves in the LC media according to the invention low threshold voltages, low rotational viscosities and very good low temperature stability with constant high bright spots and high HR values ​​and allows particularly low pretilt angles to be established quickly in PSA displays. In particular, the LC media show significantly shortened response times, in particular also gray-to-gray response times, in PSA displays relative to the media of the prior art.

[0614] The LC media and LC host mixtures according to the invention preferably have a nematic phase range of at least 80 K, particularly preferably at least 100 K, and a rotational viscosity at 20° C. of ≤250 mPa·s, preferably ≤200 mPa·s.

[0615] In a VA display according to the invention, the molecules in the layer of the liquid-crystal medium are aligned perpendicularly to the electrode surface (homeotropically) or have a tilted homeotropic alignment in the off state. When a voltage is applied to the electrodes, a realignment of the LC molecules occurs with their longitudinal axes parallel to the electrode surface.

[0616] According to a first preferred embodiment, the LC media according to the invention based on compounds with negative dielectric anisotropy, in particular for use in displays of the PS-VA, PS-UB-FFS and SA-VA type, have a negative dielectric anisotropy Δε, preferably of -0.5 to -10, in particular -2.5 to -7.5 at 20° C. and 1 kHz.

[0617] In the LC media according to the invention for use in displays of the PS-VA, PS-UB-FFS and SA-VA type, the birefringence Δn is preferably below 0.16, particularly preferably in the range from 0.06 to 0.14, very particularly preferably in the range from 0.07 to 0.12.

[0618] The LC media according to the invention may also contain further additives known to the person skilled in the art and described in the literature, such as polymerization initiators, inhibitors, stabilizers, surface-active substances or chiral dopants. These may be polymerizable or non-polymerizable. Polymerizable additives are accordingly classified as polymerizable components or component A). Non-polymerizable additives are accordingly classified as non-polymerizable components or LC component B).

[0619] In a preferred embodiment, the LC medium contains one or more chiral dopants, preferably in a concentration of 0.01-1%, very preferably 0.05-0.5%. The chiral dopant is preferably selected from the compounds of Table E below, very preferably R- or S-1011, R- or S-2011, R- or S-3011, R- or S-4011 and R- or S-5011.

[0620] In a further preferred embodiment, the LC medium contains the racemate of one or more chiral dopants, which are preferably selected from the chiral dopants mentioned in the preceding paragraphs.

[0621] Furthermore, 0 to 15% by weight of pleochroic dyes can be added to the LC medium, as well as nanoparticles, conductive salts for improving the conductivity, preferably ethyldimethyldodecylammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylborate or complex salts of crown ethers (cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258 (1973)), or substances for modifying the dielectric anisotropy, viscosity and / or nematic alignment. Such substances are described, for example, in DE-A 22 09 127, 2240 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728.

[0622] The components of the preferred embodiments a) to z) of the LC media according to the invention are either known or the person skilled in the art can easily derive their preparation from the prior art, since they are based on standard processes described in the literature. The corresponding compounds of the formula CY are described, for example, in EP-A-0 364 538. The corresponding compounds of the formula ZK are described, for example, in DE-A-26 36 684 and DE-A-33 21 373.

[0623] The LC media which can be used according to the invention are prepared in a manner conventional per se, for example by mixing one or more of the abovementioned compounds with one or more polymerizable compounds as defined above, and optionally with further liquid-crystalline compounds and / or additives. Usually, the required amount of the component used in smaller amounts is dissolved in the component constituting the main constituent, advantageously at elevated temperature. It is also possible to mix solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again after thorough mixing, for example by distillation. The invention also relates to a process for preparing the LC media according to the invention.

[0624] It goes without saying for the person skilled in the art that the LC media according to the invention may also comprise compounds in which, for example, H, N, O, Cl, F have been replaced by corresponding isotopes, such as deuterium or the like.

[0625] The following examples illustrate the present invention, but are not intended to limit it. However, they show preferred mixture concepts with preferred compounds and their respective concentrations and combinations with each other for those skilled in the art. In addition, these examples illustrate what properties and property combinations can be obtained.

[0626] Preferred mixture compositions are shown in Table D below.

[0627] In the present invention and in particular in the following examples, the structures of the mesogenic compounds are represented by abbreviations, which are also referred to as acronyms. In these acronyms, the chemical formulae are abbreviated as follows using the following Tables A to C. All groups C n H 2n+1 , C m H 2m+1 and C l H 2l+1 or C n H 2n-1 , C m H 2m-1 and C l H 2l-1 Respectively represent straight chain alkyl or alkenyl, preferably 1-E-alkenyl, each having n, m or 1 C atoms in each case.Table A shows the code for the ring element of the compound core structure, while Table B shows the linking group.Table C represents the meaning of the left-hand side or right-hand side end group code.The acronym is composed of the following: the code of the ring element with optional linking base, followed by the first hyphen and the left-hand end group code and the second hyphen and the right-hand end group code.Table D shows the exemplary structure of the compound with each abbreviation.

[0628] Table A: Ring Elements

[0629]

[0630]

[0631]

[0632]

[0633] Table B: Linking Groups

[0634]

[0635] Table C: End Groups

[0636]

[0637]

[0638]

[0639] Where n and m are each integers and three dots "..." are placeholders for other abbreviations in this table.

[0640] The following table shows exemplary structures and their respective abbreviations. These are shown to demonstrate the meaning of the abbreviation rules. In addition to the compounds of formula I, the mixtures according to the invention preferably comprise one or more of the compounds described below.

[0641] The following abbreviations are used:

[0642] (n, m and z are in each case independently of one another an integer, preferably 1 to 6).

[0643] Table D: Illustrative Structure

[0644]

[0645]

[0646]

[0647]

[0648]

[0649]

[0650]

[0651]

[0652]

[0653]

[0654]

[0655]

[0656]

[0657]

[0658]

[0659]

[0660]

[0661]

[0662]

[0663]

[0664]

[0665]

[0666] In a preferred embodiment of the invention, the LC media according to the invention, in particular those having a negative dielectric anisotropy, comprise one or more compounds selected from the compounds of table D.

[0667] Table E

[0668] Table E shows possible chiral dopants which can be added to the LC media according to the invention.

[0669]

[0670]

[0671] The LC medium preferably comprises 0 to 10% by weight, in particular 0.01 to 5% by weight, particularly preferably 0.1 to 3% by weight, of dopant. The LC medium preferably comprises one or more dopants selected from the compounds of Table B.

[0672] Table F

[0673] Table F shows possible stabilizers which can be added to the LC media according to the invention. Here n represents an integer from 1 to 12, preferably 1, 2, 3, 4, 5, 6, 7 or 8, and the terminal methyl groups are not shown.

[0674]

[0675]

[0676]

[0677]

[0678]

[0679]

[0680] 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 stabilizer. The LC medium preferably comprises one or more stabilizers selected from the compounds of Table F.

[0681] Table G

[0682] Table G shows self-aligning additives for homeotropic alignment which can be used together with the polymerisable compounds of the formula I in the LC media according to the invention:

[0683]

[0684]

[0685]

[0686]

[0687]

[0688]

[0689]

[0690]

[0691] In a preferred embodiment, the LC media and displays according to the invention comprise one or more SA additives selected from the group consisting of formulae SA-1 to SA-34, preferably formulae SA-14 to SA-34, very preferably formulae SA-20 to SA-28, most preferably formula SA-20, and one or more RMs of formula I. Very preferred is the combination of polymerisable compounds 1, 2 or 3 of Example 1 below, very preferably polymerisable compound 3 of Example 1, with an SA additive of formulae SA-20 to SA-28, very preferably formula SA-20. Example

[0692] The following examples illustrate the present invention, but are not intended to limit it. However, they show preferred mixture concepts with preferred compounds and their respective concentrations and combinations with each other for those skilled in the art. In addition, these examples illustrate what properties and combinations of properties can be obtained.

[0693] In addition, the following abbreviations and symbols are used:

[0694] V0 is the threshold voltage, capacitive [V], at 20°C,

[0695] n e Indicates the extraordinary refractive index at 20°C and 589nm,

[0696] n o It represents the ordinary refractive index at 20℃ and 589nm.

[0697] Δn represents the optical anisotropy at 20°C and 589 nm,

[0698] ε ⊥ represents the dielectric constant perpendicular to the director at 20°C and 1kHz,

[0699] ε || represents the dielectric constant parallel to the director at 20°C and 1kHz,

[0700] Δε represents the dielectric anisotropy at 20°C and 1kHz,

[0701] cl.p.,T(N,I) represents the clearing point [℃],

[0702] γ1 represents the rotational viscosity at 20°C [mPa·s],

[0703] K1 is the elastic constant, the "slant extension" deformation at 20°C [pN],

[0704] K2 is the elastic constant, the "twist" deformation at 20°C [pN],

[0705] K3 represents the elastic constant, the "bending" deformation at 20°C [pN].

[0706] Unless expressly stated otherwise, all concentrations in the present application are percentages by weight and are based on the corresponding entire mixture comprising all solid or liquid-crystalline components without solvent.

[0707] Unless expressly stated otherwise, all temperature values ​​indicated in this application, such as melting point T(C,N), transition from smectic (S) phase to nematic (N) phase T(S,N) and clearing point T(N,I), are expressed in degrees Celsius (°C). Mp stands for melting point, cl.p. = clearing point. In addition, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent transition temperatures.

[0708] All physical properties were determined in accordance with “Merck Liquid Crystals, Physical Properties of Liquid Crystals”, Status November 1997, Merck KGaA (Germany) and apply to a temperature of 20° C., with Δn at 589 nm and Δε at 1 kHz, unless expressly stated otherwise in each case.

[0709] For the present invention, the term "threshold voltage" refers to the capacitive threshold (V0), also known as the Freedericks threshold, unless otherwise expressly stated. In the embodiments, as is generally the case, the relative contrast ratio (V 10 ).

[0710] Unless otherwise stated, the process for polymerizing the polymerizable compounds in a PSA display as described above and below is carried out at a temperature at which the liquid-crystalline medium exhibits a liquid-crystalline phase, preferably a nematic phase, most preferably at room temperature.

[0711] Unless otherwise stated, the methods for preparing the test cells and measuring their electro-optical and other properties were carried out by the methods described below or by methods analogous thereto.

[0712] The display used to measure the capacitive threshold voltage consisted of two plane-parallel glass outer plates separated by 25 μm, each of which had an electrode layer on the inside and an unrubbed polyimide alignment layer on top, which resulted in homeotropic edge alignment of the liquid crystal molecules.

[0713] The display or test cell used to measure the tilt angle consists of two plane-parallel glass outer plates separated by 4 μm, each of which has an electrode layer on the inside and a polyimide alignment layer on top, wherein the two polyimide layers are rubbed antiparallel to each other and cause homeotropic edge alignment of the liquid crystal molecules.

[0714] The polymerizable compound is polymerized in the display or test box by irradiating with UV light of a certain intensity for a predetermined time while applying a voltage (usually 10V-30V AC, 1kHz) to the display. In the examples, unless otherwise stated, a metal halide lamp and 100mW / cm2 The intensity was measured using a standard instrument (Hoenle UV-meter high end with UV sensor).

[0715] The tilt angle was determined using the Mueller Matrix Polarimeter "AxoScan" from Axometrics. Small values ​​(ie large deviations from an angle of 90°) correspond here to large tilts.

[0716] Unless otherwise specified, 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 optical principal axes of the LC molecules in a LC molecule layer having uniform orientation, which in the case of rod-shaped uniaxial positively birefringent LC molecules corresponds to their molecular long axes.

[0717] Example 1: Polymerizable compounds

[0718] A polymerizable compound (or "RM") RM-1 was prepared as follows

[0719]

[0720] 1.4: At 0°C, a sodium hydride suspension (5.4 g, 60% in mineral oil, 135.6 mmol) was added to a stirred solution of benzyl alcohol 1.3 (20.0 g, 113.0 mmol) in THF (20 mL). The resulting mixture was stirred at the same temperature for 10 minutes and then treated with methyl iodide (8.7 mL, 135.6 mmol). The reaction mixture was stirred at ambient temperature for 4 hours, carefully quenched with water and extracted with ethyl acetate. The aqueous phase was separated and extracted with ethyl acetate (2 times). The combined organic phases were washed with saturated NaCl solution, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by flash chromatography (heptane) to give 1.4 as a colorless oil. (21.0 g, 97%; GC: 99.9%).

[0721]

[0722] 1.6: Hydrazine hydrate (0.2 mL, 80%, 0.004 mol) was added to a stirred solution of sodium metaborate tetrahydrate (43.3 g, 0.314 mol) and PdCl2[P(cy)3]2 (3.1 g, 0.004 mol) in THF (5 mL) / water (60 mL) at room temperature. The resulting mixture was stirred at ambient temperature for 5 minutes and then treated with a solution of 1.4 (20.0 g, 0.105 mol) and 1.5 (74.9 g, 0.199 mol) in THF (520 mL). The reaction mixture was stirred at 70°C overnight, the phases were separated, and the aqueous phase was extracted with methyl tert-butyl ether (2 times). The combined organics were washed with water, dried over Na2SO4, filtered and concentrated in vacuo. The residue (67.0 g, 103%) was used in the next step without further purification.

[0723]

[0724] 1.7: A solution of TBAF (1.0 M in THF, 158 mL, 158 mmol) was added dropwise to a stirred solution of 1.6 (42.0 g, 67.8 mmol) in THF (500 mL) at 5°C. The resulting mixture was stirred at 3°C ​​for 30 minutes and then at ambient temperature for 1 hour before being poured onto 40 mL of ice, acidified to pH=6 with HCl (2.0 M) and extracted with ethyl acetate (3 times). The combined organic phases were washed with saturated NaCl solution, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by flash chromatography (dichloromethane / methanol) to give 1.7 (9.6 g, 46%) as white crystals.

[0725]

[0726] RM-1: Methacrylic acid (6.7 g, 78.3 mmol) and 4-dimethylaminopyridine (DMAP, 0.38 g, 3.1 mmol) were added to a stirred solution of biphenol 1.7 (9.6 g, 31.1 mmol) in dichloromethane (150 mL) at room temperature. The resulting mixture was cooled to 3°C and then a solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (12.2 g, 78.3 mmol) in dichloromethane (20 mL) was added dropwise. The reaction mixture was warmed to room temperature and stirred overnight and then concentrated in vacuo. The residue was purified by flash chromatography (heptane / ethyl acetate) and recrystallized from heptane / ethanol (2:1) to give 1 (10.2 g, 74%; HPLC: 99.7%) as white crystals.

[0727] 1H NMR(CDCl3):2.12–2.13(m,6H),3.41(s,3H),4.43(s,2H),5.80–5.82(m,2H),6.41–6.42(m,2H),7.27–7.21(m,4H),7.40 (d,J=7.9Hz,1H),7.45–7.49(m,2H),7.60(dd,J=7.9,2.0Hz,1H),7.74–7.65(m,2H),7.78(d,J=1.9Hz,1H); EI-MS: 442.0.

[0728] DSC:Tg 0 K 117 I.

[0729] Similar to polymerizable compound RM-1, the following compounds were synthesized:

[0730] Example 2: RM-2

[0731]

[0732] RM-2: Melting point: 117°C. 1 H NMR(CDCl3): δ7.76(d,J=2.3Hz,1H),7.72–7.66(m,6H),7.62(dd,J=8.3,2.4Hz,1H),7.27–7.22(m,3H),6.42(dt,J=8.0,1. 2Hz,2H),5.82(dp,J=7.9,1.6Hz,2H),4.51(s,2H),3.43(s,3H),2.13(t,J=1.2Hz,3H),2.12(t,J=1.3Hz,3H).EI-MS:442.2

[0733] Example 3: RM-3

[0734]

[0735] RM-3: Melting point: 74°C. 1 H NMR (CDCl3): δ7.69(d,J=2.3Hz,1H),7.65–7.61(m,2H),7.55(dd,J=8.3,2.4Hz,1H),7.26–7.19(m,3H),6.41(dt,J=8.3,1. 2Hz,2H),5.81(dt,J=8.3,1.6Hz,2H),4.49(s,2H),3.42(s,3H),2.12(t,J=1.3Hz,3H),2.11(t,J=1.2Hz,3H).EI-MS: 366.0

[0736] Example 4: RM-4

[0737]

[0738] 4a: To a solution of (2-bromo-5-iodo-phenyl)-methanol (100.0 g, 0.32 mol) in 250 ml THF was added sodium hydride (15.3 g, 0.38 mol) at 0°C in several portions. The reaction mixture was stirred at 0°C for 30 minutes, methyl iodide (24.5 ml, 0.38 mol) was added dropwise thereto, and then stirred at room temperature for 1 hour. The reaction mixture was carefully treated with ice water and extracted with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate and filtered. After removing the solvent in vacuo, the crude product obtained was purified by silica gel column chromatography to give 4a (85.5 g) as a yellow oil.

[0739] 4b: Add 4a (9.5 g, 29.0 mmol) and 2-fluoro-4-hydroxyphenylboronic acid (4.8 g, 30.5 mmol) to 50 ml of 1,4-dihydroquinone. Sodium carbonate (6.5 g, 61 mmol) and 13 ml of distilled water were added to the oxane solution. After careful degassing with argon, [1,1'-bis(diphenylphosphino)ferrocene]dichloro-palladium(II) (0.85 g, 1.2 mmol) was added. The reaction mixture was heated to reflux and stirred overnight. After cooling to room temperature, the reaction mixture was carefully neutralized with 2M HCl. The aqueous phase was separated and extracted with ethyl acetate. The organic phases were combined, dried over anhydrous sodium sulfate and filtered. After removing the solvent in vacuo, the obtained crude product was purified by silica gel column chromatography to obtain 4b (5.6 g) as a white solid.

[0740] 4c: Add 4b (5.6 g, 18 mmol) to 125 ml of 1,4-dihydro To a mixture of oxane and KOH (2.2 g, 39 mmol) in 3 ml of distilled water was added Pd2(dba)3 (0.56 g, 0.61 mmol) and t Bu-X-Phos (0.97 g, 2.23 mmol). The reaction mixture was heated to reflux and stirred overnight. After cooling to room temperature, the reaction mixture was carefully neutralized with 2M HCl. The aqueous phase was separated and extracted with toluene. The organic phases were combined, dried over anhydrous sodium sulfate, and filtered. After removing the solvent in vacuo, the resulting crude product was purified by silica gel column chromatography using a heptane / ethyl acetate mixture as eluent to give 4c (1.0 g) as a brown oil.

[0741] RM-4: Methacrylic acid (0.78 ml, 9.3 mmol) and 4-(dimethylamino)pyridine (0.049 g, 0.4 mmol) were added to a solution of 1c (1.0 g, 4.0 mmol) in dichloromethane. The reaction mixture was dropwise treated with a DCM solution of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (1.5 g, 9.7 mmol) at 0°C and stirred at room temperature for 2 hours. The reaction mixture was concentrated in vacuo and the oily residue was purified by silica gel column chromatography using a heptane / ethyl acetate mixture as eluent to give RM-4 (0.69 g) as a white solid.

[0742] Similar to Example 4, the following polymerizable compounds were synthesized:

[0743] Example 5: RM-5

[0744]

[0745] Example 6: RM-6

[0746]

[0747] Mixture Examples

[0748] The LC media according to the invention are prepared using the following liquid-crystal mixtures consisting of the low molecular weight components in the indicated percentages by weight (for acronyms see the table above).

[0749] H1: Nematic host mixture (Δε<0)

[0750]

[0751] H2: Nematic host mixture (Δε<0)

[0752]

[0753]

[0754] H3: Nematic host mixture (Δε<0)

[0755]

[0756] H4: Nematic host mixture (Δε<0)

[0757]

[0758] H5: Nematic host mixture (Δε<0)

[0759]

[0760] H6: Nematic host mixture (Δε<0)

[0761]

[0762] H7: Nematic host mixture (Δε<0)

[0763]

[0764]

[0765] H8: Nematic host mixture (Δε<0)

[0766]

[0767] H9: Nematic host mixture (Δε<0)

[0768]

[0769]

[0770] H10: Nematic host mixture (Δε<0)

[0771]

[0772] H11: Nematic host mixture (Δε<0)

[0773]

[0774] H12: Nematic host mixture (Δε<0)

[0775]

[0776]

[0777] H13: Nematic host mixture (Δε<0)

[0778]

[0779] H14: Nematic host mixture (Δε<0)

[0780]

[0781]

[0782] H15: Nematic host mixture (Δε<0)

[0783]

[0784] H16: Nematic host mixture (Δε<0)

[0785]

[0786]

[0787] H17: Nematic host mixture (Δε<0)

[0788]

[0789] H18: Nematic host mixture (Δε<0)

[0790]

[0791]

[0792] H19: Nematic host mixture (Δε>0)

[0793]

[0794] H20: Nematic host mixture (Δε>0)

[0795]

[0796] H21: Nematic host mixture (Δε>0)

[0797]

[0798] H22: Nematic host mixture (Δε>0)

[0799]

[0800] H23: Nematic host mixture (Δε>0)

[0801]

[0802]

[0803] H24: Nematic host mixture (Δε>0)

[0804]

[0805] H25: Nematic host mixture (Δε<0)

[0806]

[0807]

[0808] H26: Nematic host mixture (Δε<0)

[0809]

[0810] H27: Nematic host mixture (Δε<0)

[0811]

[0812]

[0813] H28: Nematic host mixture (Δε<0)

[0814]

[0815] H29: Nematic host mixture (Δε<0)

[0816]

[0817]

[0818] H30: Nematic host mixture (Δε<0)

[0819]

[0820] H31: Nematic host mixture (Δε<0)

[0821]

[0822] H32: Nematic host mixture (Δε<0)

[0823]

[0824] H33: Nematic host mixture (Δε<0)

[0825]

[0826]

[0827] H34: Nematic host mixture (Δε<0)

[0828]

[0829] H35: Nematic host mixture (Δε<0)

[0830]

[0831]

[0832] H36: Nematic host mixture (Δε<0)

[0833]

[0834] H37: Nematic host mixture (Δε<0)

[0835]

[0836]

[0837] H38: Nematic host mixture (Δε<0)

[0838]

[0839] H39: Nematic host mixture (Δε<0)

[0840]

[0841]

[0842] H40: Nematic host mixture (Δε<0)

[0843]

[0844] H41: Nematic host mixture (Δε<0)

[0845]

[0846]

[0847] H42: Nematic host mixture (Δε<0)

[0848]

[0849] H43: Nematic host mixture (Δε<0)

[0850]

[0851] H44: Nematic host mixture (Δε<0)

[0852]

[0853] H45: Nematic host mixture (Δε<0)

[0854]

[0855] H46: Nematic host mixture (Δε<0)

[0856]

[0857]

[0858] H47: Nematic host mixture (Δε<0)

[0859]

[0860] General Procedure for Mixture Examples

[0861] A polymerizable mixture is prepared by adding the polymerizable compound of Synthesis Examples 1 to 6 (e.g., RM-3, 0.3%) and one or more homeotropically aligned self-aligning additives selected from Table G (e.g., SA-20, 1.0%) to any of the above nematic host mixtures H1 to H47.

[0862] Mixture Example 1: Polymerizable Mixture P1

[0863] The polymerizable mixture P1 according to the present invention was prepared by adding the polymerizable compound 3 (0.30%) and the self-aligning additive SA-20 to the nematic LC host mixture H1.

[0864]

[0865] Comparative Mixture Example: Polymerizable Mixture C1

[0866] For comparative purposes, polymerizable mixture C1 was prepared by replacing the polymerizable compound with compound RM-C1 having a biphenyl core without pendant substituents.

[0867]

[0868] The concentration of RM in the polymerizable mixture was 0.3% by weight each. The composition of each polymerizable mixture is shown in Table 1.

[0869] Table 1. Liquid crystal components (LC component B) (LC host), polymerizable compounds (RM) and self-aligning additives (SA, polymerizable A mixture of:

[0870] Mixture No. C1 P1 LC body H1 H1 RM RM-C1 RM-3 wt.%RM 0.30 0.30 S SA-20 SA-20 wt.%SA 1.0 1.0

[0871] Application Examples

[0872] Each polymerizable mixture was filled into a PSA test cell, the RM was polymerized under applied voltage, and several properties such as residual RM content, VHR under backlight stress, tilt angle generation, and tilt angle stability were measured.

[0873] Residual RM measurement

[0874] The content of residual, unpolymerized RM in the mixture after UV exposure was determined (in wt%). The UV treatment was similar to the process conditions in panel manufacturing (first UV cure for 2 minutes; second UV final cure for 120 minutes).

[0875] For this purpose, the polymerizable mixture was filled into an electro-optical test cell made of soda-lime glass coated with an approximately 200 nm thick ITO layer with a cell gap of 6-7 μm.

[0876] The test box was irradiated by MH lamp (UV-Cube2000) for 2 minutes using 320 nm long pass filter (N-WG320) and 100 mW / cm2 light intensity, resulting in polymerization of RM. Final curing was performed using C-type light source for 120 minutes.

[0877] After polymerization, the test box was opened, the mixture was dissolved and washed out of the test box with 2 ml of ethyl methyl ketone, and analyzed by high performance liquid chromatography (HPLC).

[0878] Table 2. Residual RM content:

[0879]

[0880] For the polymerizable mixture according to the invention, no residual RM was detected within a detection limit of about 0.001%. In the comparative mixture, 0.004% of RM-C1 could be detected.

[0881] As can be seen from Table 2, for the polymerizable mixture with RM-3 according to the present invention, the amount of residual RM is significantly lower compared to the polymerizable mixture with conventional RM-C1.

[0882] Voltage Holding Ratio (VHR)

[0883] To measure the VHR, the polymerizable mixture was filled into an electro-optical test cell consisting of two AF glass substrates and an approximately 20 nm thick ITO layer.

[0884] VHR was measured by applying 1 V / 60 Hz voltage at 60 °C before and after illumination. VHR was determined before and after UV treatment and after 6 days of backlight stress. UV treatment for VHR measurement: Metal halide lamp (100 mW / cm 3 , with 320 nm cut-off filter for 120 min); Backlight stress: stored at 40°C under high power backlight.

[0885] The difference in VHR between different RMs (based on RM-C1) is expressed as follows:

[0886] ΔVHR=VHR RM -VHR RM-C1

[0887] Positive values ​​correspond to an improvement in VHR relative to the reference RM-C1 and negative values ​​indicate a decrease in VHR relative to the reference.

[0888] The results are shown in Table 3.

[0889] Table 3. Differences in VHR values ​​between reference RM-C1 mixture and samples:

[0890]

[0891] It can be seen from Table 3 that the RM according to the present invention is able to maintain the VHR level of the reference RM-C1.

[0892] Tilt Angle Generation

[0893] To measure the tilt angle generation, the polymerizable mixture was filled into an electro-optical test cell made of two soda-lime glass substrates coated with an ITO electrode layer of about 200 nm thickness, without a VA-polyimide alignment layer. The cell gap was about 4 μm.

[0894] The test box was illuminated by a MH-lamp (UV-Cube 2000) using a 320nm long pass filter (N-WG320), with a light intensity of 100mW / cm2, a temperature of 20°C, and an applied square wave voltage of 24V RMS (AC, 1 kHz), resulting in polymerization of RM and generation of tilt angle. Irradiation times are given in the tables. The resulting tilt was measured after a period of 12 hours using a Mueller Matrix Polarimeter "AxoScan" from Axometrics. The results are shown in Table 4.

[0895] Table 4. Tilt angle generation:

[0896]

[0897] As can be seen from Table 4, in the LC host H1 having the RM according to the present invention, the tilt angle generation results in a desired tilt angle of 85° (5° from vertical), while the comparative tilt angle is 8° from vertical, which is somewhat beyond the optimal range.

[0898] Tilt stability

[0899] The mixture was filled into a test cell made of soda lime glass coated with a 200 nm layer of ITO and a 30 nm layer of polyimide (JALS-2096-R1). The polyimide layers were rubbed antiparallel to each other. The cell gap was about 4 μm.

[0900] Irradiation was performed by a metal halide lamp (UV-Cube 2000) with a 320 nm long pass filter (N-WG320) at a light intensity of 100 mW / cm2, a temperature of 20 °C, and an applied square wave voltage of 10 V. RMS (1 khz), resulting in a tilt. The resulting tilt was measured after a period of 12 hours using a Mueller Matrix Polarimeter "AxoScan" from Axometrics.

[0901] For RM-C1, a pre-tilt of 84.8° was generated in N3; and for RM, a tilt angle of 87.5° was generated in N3. Then, a 10V at a frequency of 1kHz was used. RMS The cell was electrically stressed at 40°C for 168 hours with a square wave of . After a relaxation time of 10-20 minutes, the tilt angle was measured again. The results are shown in Table 5 below according to the following equation:

[0902] Tilt 在应力之后 –tilt 在倾斜产生之后 =Δ-tilt

[0903] The closer the value is to 0, the more stable the tilt generated. High tilt stability is also an indication for reducing image sticking in the display.

[0904] Table 5. Tilt stability:

[0905] mixture ΔTilt / ° P1 0.5 C1 0.5

[0906] As can be seen from Table 5, the tilt produced using RM-3 is as stable as that produced by the comparative RM-C1.

[0907] Overall, the above results indicate that the RMs according to the present invention are able to achieve fast UV curing and complete polymerization while maintaining low ion content and high VHR in the mixture after UV treatment, and are able to produce tuned tilt angles with high tilt stability after electrical stress.

[0908] Therefore, the RM according to the present invention shows superior overall performance relative to the RM of the prior art.

Claims

1. Liquid crystal (LC) medium, including - a polymerizable component A) comprising one or more polymerizable compounds of formula I, a liquid crystal LC component B) comprising one or more mesogenic or liquid crystal compounds, and - one or more self-aligning additives for vertical alignment of formula II Wherein formula I and II are defined as follows: P-Sp-A 1 -(Z 1 -A 2 ) z -R I where the individual radicals, independently of one another and identically or differently on each occurrence, have the following meanings: P represents a polymerizable group, Sp represents a spacer group or a single bond, A 1 ,A 2 represents benzene or naphthalene, which is optionally substituted by one or more groups L, L 11 or P-Sp-substituted, wherein at least one group A 1 or A 2 At least one substituent L 11 replace, L 11 represents -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7, Z 1 Represents -O-,-S-,-CO-,-CO-O-,-O-CO-,-O-CO-O-,-OCH2-,-CH2O-,-SCH2-,-CH2S-,-CF2O-,-OCF2-,-CF2S-,-SCF2-,-(CH2) n1 -,-CF2CH2-,-CH2CF2-,-(CF2) n1 -,-CH=CH-,-CF=CF-,-CH=CF-,-CF=CH-,-C≡C-,-CH=CH-CO-O-,-O-CO-CH=CH-,-CH2-CH2-CO-O-,-O-CO-CH2-CH2-,-CR 0 R 00 - or single key, R 0 ,R 00 represents H or an alkyl group having 1 to 12 C atoms, R stands for H, L, L 11 or P-Sp-, L represents F, Cl, -CN, P-Sp- or a straight-chain, branched or cyclic alkyl radical having 1 to 25 C atoms, wherein one or more non-adjacent CH2-groups are optionally replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that the O- and / or S-atoms are not directly connected to one another, and wherein one or more H atoms are each optionally replaced by P-Sp-, F or Cl, z represents 1, 2, or 3, and n1 means 1, 2, 3 or 4; MES-R a II in MES is a rod-shaped mesogenic group comprising two or more rings, which are directly or indirectly linked to one another or which are fused to one another, whose rings are optionally substituted and the mesogenic group is optionally additionally substituted by one or more polymerizable groups, which are linked directly or via a spacer to the MES, and R a is a polar anchoring group located at the terminal position of the rod-shaped mesogen group MES, the anchoring group comprising at least one carbon atom and at least one group selected from -OH, -SH, -COOH, -CHO or a primary or secondary amine functional group, and the anchoring group optionally comprises one or two polymerizable groups P.

2. A liquid crystal medium according to claim 1, wherein in formula I, -A 1 -(ZA 2 ) z - is selected from the following formula, At least one ring is surrounded by at least one group L 11 The phenyl ring is optionally further substituted by one or more groups L or P-Sp- as defined in claim 1.

3. A liquid-crystalline medium according to claim 1 or 2, wherein formula I is selected from the following subformulae: in, r1, r3, r6 are independently 0, 1, 2 or 3, r2 is 0, 1, 2, 3, or 4, r4, r5 are independently 0, 1 or 2, wherein r1+r6≥1, r1+r2+r3≥1, r4+r5≥1, r1+r3+r4≥1 and at least one group L represents -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7, and In formula I1, at least one group Sp is a single bond.

4. A liquid-crystalline medium according to claim 1 or 2, wherein formula I is selected from the following subformulae: wherein P, Sp, L, r1-r6 have the meanings given in claim 3, and at least one group L represents -CH2-O-CH3, -CH2-O-C2H5 or -CH2-O-C3H7. 5 . The liquid-crystalline medium according to claim 1 , wherein in formula I, P represents an acrylate group or a methacrylate group.

6. A liquid crystal medium according to claim 1 or 2, wherein in formula I, Sp is a single bond or represents -(CH2) p2 -、-(CH2) p2 -O-, -(CH2) p2 -CO-O-, -(CH2) p2 -O-CO-, wherein p2 is 2, 3, 4, 5 or 6, and the O-atom or CO-group is connected to the benzene ring, respectively.

7. A liquid crystal medium according to claim 1 or 2, wherein the self-aligning additive for vertical alignment is of the formula IIa R 1 -[A 2 -Z 2 ] m -A 1 -R a IIa in, A 1 ,A 2 each independently of one another represents an aromatic, heteroaromatic, alicyclic or heterocyclic radical, which may also contain fused rings and which may also be substituted by a radical L 1 or -Sp-P is singly or polysubstituted, L 1 represents, in each case independently of one another, F, Cl, Br, I, -CN, -NO2, -NCO, -NCS, -OCN, -SCN, -C(=O)N(R 0 )2, -C(=O)R 0 , optionally substituted silyl, optionally substituted aryl or cycloalkyl having 3 to 20 C atoms, or linear or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having up to 25 C atoms, wherein, in addition, one or more H atoms are optionally each replaced by F or Cl, P represents a polymerizable group, Sp represents a spacer group or a single bond, Z 2 represents, independently of one another, a single bond, -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 ) n1 -, -CH(-Sp-P)-, -CH2CH-(-Sp-P)- or -CH(-Sp-P)CH(-Sp-P)-, n1 means 1, 2, 3 or 4, m means 1, 2, 3, 4 or 5, R 0 represents in each case, independently of one another, an alkyl radical having 1 to 12 C atoms, R 00 in each case independently of one another represents H or alkyl having 1 to 12 C atoms, R 1 independently of one another denotes H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein in addition, one or more non-adjacent CH2 groups are optionally each replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, or -O-CO-O- in such a way that the O and / or S atoms are not directly connected to one another, and wherein in addition, one or more H atoms are optionally each replaced by F or Cl, or independently of one another denotes the group -Sp-P, and R a represents a polar anchoring group as defined in claim 1.

8. A liquid-crystalline medium according to claim 1 or 2, wherein the self-aligning additive has an anchoring group R selected from the following formula a in p means 1 or 2, q means 2 or 3, B represents a substituted or unsubstituted ring system or a condensed ring system, Y independently represents -O-, -S-, -C(O)-, -C(O)O-, -OC(O)-, -NR 11 - or single key, o means 0 or 1, X 1 Each independently represents H, alkyl, fluoroalkyl, OH, NH2, NHR 11 NR 11 2. OR 11 , C(O)OH or -CHO, At least one group X 1 It represents a compound selected from -OH, -NH2, NHR 11 , C(O)OH and -CHO groups, R 11 represents an alkyl group having 1 to 12 C atoms, Sp a ,Sp c ,Sp d each independently of one another represents a spacer group or a single bond, and Sp b represents a trivalent or tetravalent group.

9. A liquid-crystalline medium according to claim 1 or 2, wherein the self-aligning additive for homeotropic alignment is a compound selected from the group consisting of the formulae II-A to II-D, Where R 1 , R a , A 2 , Z 2 , Sp, P and L 1 has the meaning as defined in formula IIa of claim 7, m is 1, 2, 3, or 4, and r1 is 0, 1, 2, 3, or 4.

10. Liquid-crystalline medium according to claim 1 or 2, characterized in that It comprises one or more compounds of formula CY and / or PY: The various groups have the following meanings: a means 1 or 2, b represents 0 or 1, express R 1 and R 2 each independently of one another represents an alkyl group having 1 to 12 C atoms, wherein, in addition, one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another, Z x Indicates -CH=CH-, -CH2O-, -OCH2-, -CF2O-, -OCF2-, -O-, -CH2-, -CH2CH2- or a single bond, L 1-4 Each independently represents F, Cl, OCF3, CF3, CH3, CH2F, CHF2.

11. Liquid-crystalline medium according to claim 1 or 2, characterized in that It contains one or more compounds of the following formula: The various groups have the following meanings: express express R 3 and R 4 each independently of one another represents an alkyl radical having 1 to 12 C atoms, wherein in addition one or two non-adjacent CH2 groups may be replaced by -O-, -CH=CH-, -CO-, -O-CO- or -CO-O- in such a way that the O atoms are not directly connected to one another, Z y Represents a single bond, -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -COO-, -OCO-, -C2F4- or -CF=CF-.

12. Liquid-crystalline medium according to claim 1 or 2, characterized in that The polymerizable compound of formula I has been polymerized.

13. A method for preparing a liquid crystal medium according to any one of claims 1 to 12, comprising the following steps: A liquid-crystalline component B) as defined in claim 1 is mixed with one or more compounds of the formula I as defined in any one of claims 1 to 6, one or more compounds of the formula II and optionally further liquid-crystalline compounds and / or additives.

14. An LC display comprising a liquid-crystalline medium as defined in any of claims 1 to 12.

15. An LC display according to claim 14 which is a PSA display.

16. LC display according to claim 15 which is PS-VA, PS-UB-FFS, PS-positive-VA, polymer-stabilised SA-VA.

17. An LC display according to claim 15 or 16, characterised in that It comprises two substrates, at least one of which is light-transmissive, an electrode provided on each substrate or two electrodes provided on only one substrate, and a layer of a liquid crystal medium as defined in any of claims 1 to 12 located between the two substrates, wherein the polymerizable compound is polymerized between the substrates of the display.

18. A method for producing an LC display according to any one of claims 14 to 16, comprising the following steps: Providing a liquid crystal medium as defined in any one of claims 1 to 12 between substrates of a display and polymerizing the polymerizable compound.

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