Additives for liquid crystal mixtures

Abstract

The invention relates to liquid-crystal mixtures comprising polyfluorinated additives, and to liquid-crystal displays based on these mixtures.

Description

[0001] The invention relates to liquid-crystal mixtures comprising polyfluorinated additives and to liquid-crystal displays based on these mixtures.

[0002] Since the discovery of the first commercially available liquid crystal compounds about 40 years ago, liquid crystals have found a wide range of applications. Known fields of application today are simple digital displays, displays for portable and desktop computers, navigation systems and, in particular, also television sets. In particular, for displays that can play videos, high requirements are placed on the response time and the contrast of the image.

[0003] The spatial arrangement of the molecules in a liquid crystal has the effect that many of its properties are direction-dependent. Of particular importance for use in liquid crystal displays are the anisotropies in the optical, dielectric and elastomechanical behavior. Depending on whether the molecules are oriented with their longitudinal axis perpendicular or parallel to the two plates of the capacitor, they have different capacitances; in other words, the dielectric constant ε of the liquid crystal medium has different values ​​for the two orientations. A substance is said to be dielectrically positive if its dielectric constant is greater when the longitudinal axis of the molecules is oriented perpendicular to the capacitor plates than when they are oriented parallel. In other words, if the dielectric constant ε parallel to the longitudinal axis of the molecules is greater than the dielectric constant ε, the dielectric constant ε of the liquid crystal medium is greater than the dielectric constant ε of the liquid crystal medium. || Greater than the dielectric constant ε perpendicular to the molecular longitudinal axis ⊥ , then the dielectric anisotropy Δε=ε || -ε ⊥ Greater than 0. Most liquid crystals used in conventional displays belong to this category.

[0004] Both the polarizability and the permanent dipole moment of the molecules contribute to the dielectric anisotropy. When a voltage is applied to the display, the longitudinal axes of the molecules align themselves in the following way: the larger of the dielectric constants becomes effective. The strength of the interaction with the electric field depends here on the difference between these two constants. In the case of a smaller difference, a higher switching voltage is necessary than in the case of a larger difference. Incorporating appropriate polar groups (e.g. nitrile groups or fluorine) into the liquid crystal molecules enables a wide range of operating voltages to be achieved.

[0005] Very high-performance displays have been developed using liquid crystals in which the larger dipole moment is oriented parallel to the longitudinal axis of the molecule. Here, in most cases, a mixture of 5 to 20 components is used to strive to achieve a sufficiently wide temperature range of the mesomorphic phase and a short response time and a low threshold voltage. However, for liquid crystal displays such as those used in notebook computers, strong viewing angle dependence still poses difficulties. If the surface of the display is perpendicular to the viewing direction of the observer, the best imaging quality can be achieved. If the display is tilted relative to the viewing direction, the imaging quality deteriorates sharply in some cases. For better comfort, efforts are being made to maximize the angle at which the display can deviate from the viewing direction of the observer without significantly reducing the imaging quality. Recently, attempts have been made to use the following liquid crystal compounds to improve the viewing angle dependence, the dipole moment of the liquid crystal compound perpendicular to the longitudinal axis of the molecule is greater than the dipole moment parallel to the longitudinal axis of the molecule. In this case, the dielectric anisotropy Δε is negative. In the absence of an electric field, these molecules should be oriented with their longitudinal axis perpendicular to the glass surface of the display. By applying an electric field, they are more or less oriented parallel to the glass surface. In this way, improvements in viewing angle dependence can already be achieved. This type of display is known as a VA-TFT (“Vertically Aligned”) display or VA display for short.

[0006] Furthermore, so-called PS-VA displays based on VA displays are known. In these, polymerizable components are used in the LC medium to adjust the permanent pretilt angle by polymerization of the polymerizable components. Fast switching and high contrast can be achieved by appropriate adjustment of the magnitude and direction of the pretilt.

[0007] To switch the individual pixels on and off, most high-resolution displays are addressed by non-linear electronic elements, for example by thin-film transistors ("TFTs") Such displays are also referred to below as active-matrix displays (TFT displays).

[0008] A typical LCD device itself comprises two substrates with electrodes and a liquid crystal layer located in the space enclosed by the substrates. The image is displayed by changing the alignment of the liquid crystal by means of a voltage applied to the electrodes.

[0009] LCD displays are typically prepared by bonding a first substrate having pixel electrodes, thin film transistors (TFTs) and other components to a second substrate containing a common electrode using a sealant. Typically, the space enclosed by the substrates is filled with liquid crystals through a filling hole by means of capillary force or vacuum; the filling hole is then sealed with a sealant.

[0010] With the increase in the size of liquid crystal displays in recent years, the so-called "drop-injection" method (ODF method) has been proposed as a method for mass production of liquid crystal displays (see, for example, JPS63-179323 and JPH10-239694) in order to shorten the cycle time in the production process. This is a method for producing liquid crystal displays in which liquid crystals are dripped onto a substrate equipped with electrodes. A second substrate equipped with electrodes and / or color filters and a sealant around the edges are then installed in a vacuum, and the sealant is cured by UV radiation and heat treatment.

[0011] Today, filling active matrix liquid crystal devices by the ODF method is the preferred method for large-format displays. The skilled person is familiar with appropriate metering devices for filling liquid crystal displays by the ODF method. A prerequisite for the success of the ODF method is that the liquid crystal medium self-distributes after application to form a uniform film between the substrates. Insufficient flow behavior or the occurrence of concentration gradients may cause problems. A known problem when using conventional liquid crystal mixtures is the occurrence of so-called "ODF display mura" or "ODF drop display mura", which is characterized by, for example, periodic annular irregularities on the display surface along the droplet boundaries. Due to different flow conditions during droplet deposition and droplet convergence when the substrates are joined together, the ODF display mura occurs to different degrees, which is mainly manifested by an uneven distribution of display brightness. In the case of VA-type and MVA, PVA or PS-VA-type liquid crystal devices, the contour of the droplets is a typical problem. In addition, in the case of polymer-stabilized displays (such as PSA, PS-VA), this type of brightness difference is fixed. Conventional preventive measures, such as reducing polymer concentration, are often associated with other disadvantages, such as lower stability of tilt angle, etc. It is therefore desirable to provide liquid crystal mixtures that achieve good wetting (spreading) of substrates, have good flow properties and largely avoid the phenomenon of ODF display unevenness.

[0012] The effort to prepare the polyimide layer, to treat it and to improve it with protrusions or polymer layers is relatively large. Therefore, there is a need for a simplified technology that reduces production costs on the one hand and helps to optimize image quality (viewing angle dependence, contrast, response time) on the other hand.

[0013] Recently, an improved VA type display has been developed without a conventional polyimide alignment film by using so-called self-aligning additives for vertical alignment (WO 2012 / 038026; WO 2013 / 004372, US 2015 / 252265, WO 2017 / 041893). These displays are also called SA-VA displays. The spreading behavior of a mixture containing such an alignment additive for vertical alignment can cause a discontinuity in the concentration of the additive. In this case, areas with very low concentrations of the alignment additive may show incomplete vertical alignment in the edge areas of the display box or in certain parts of the dripping area of ​​the ODF process. A solution for making the distribution of the self-aligning additive more uniform can improve the performance of such SA-VA displays and enable lower concentrations of the additive.

[0014] The object of the present invention is therefore to improve the wetting behavior, uniform spreading and flow properties of liquid-crystal media for SA-VA displays in a targeted manner. The electro-optical and chemical properties of the mixture, which are optimized in various ways, must not be adversely affected in the process. A further object of the present invention is to provide a mixture and a process for producing such liquid-crystal displays, in which the above-described phenomena of uneven ODF display and incomplete homeotropic alignment do not occur or occur only to a tolerable extent.

[0015] There therefore continues to be a great demand for TFT displays having a very high specific resistance and at the same time a large operating temperature range, short response times even at low temperatures, and a low threshold voltage, which do not have these disadvantages or have them only to a lesser extent.

[0016] Until now, liquid crystal mixtures with a low tendency to form ODF display unevenness and incomplete alignment have attracted little attention. Publication KR 2011-0068303 proposes polysiloxane as an additive for reducing drip-type display unevenness.

[0017] It is an object of the present invention to provide liquid-crystalline media having improved properties with respect to processing and application, and to provide additives for use in liquid-crystalline media having advantageous properties.

[0018] This is achieved by providing a liquid crystal medium comprising a liquid crystal component, characterised in that it comprises one or more self-aligning additives for homeotropic alignment and one or more polyfluorinated spreading additives of the following formula I:

[0019]

[0020] in

[0021] R 1represents a straight-chain or branched alkyl group having 1 to 20 C atoms or H, wherein in this group one or more CH 2 The groups may also be independently -C≡C-, -CH=CH-, -O-, -S-, -CO-O- or -O-CO- are replaced in such a way that the O / S atoms are not directly connected to each other,

[0022] R F represents a polyfluorinated alkyl group having 4 to 25 carbon atoms and at least 9 fluorine atoms, preferably selected from the formula -R 2 , The group, R 2 In each case independently

[0023] R 1 , Rf 3 Independently represents H, F, -CF 3 , -CF 2 CF 3 , -CF 2 CF 2 CF 3 or CF(CF 3 ) 2 , preferably -CF 3 , -CF 2 CF 3 , -CF 2 CF 2 CF 3 or CF(CF 3 ) 2 , especially preferably -CF 3 ,

[0024] R 2 independently represents an unbranched, branched or cyclic fluoroalkyl group having 3 to 15 fluorine atoms and 1 to 10 C atoms, wherein one or more non-adjacent CH 2 The group may be substituted by -O- and / or -S-, especially -CF 3 , -CF 2 CF 3 , -CF 2 CF 2 CF 3 、-CH 2 CF 2 CF 2 CF 3 、-CH 2 CF 2 CF 3 ,-CF(CF 3 )-O-CF2 CF 2 CF 3 、-S-CF 2 CHF-O-CF 2 CF 2 CF 3 or CF(CF 3 ) 2 , preferably -CF 3 , -CF 2 CF 3 , -CF 2 CF 2 CF 3 or CF(CF 3 ) 2 , especially preferably -CF 3 ,

[0025] Z 1 represents, independently in each case, a single bond, -CH 2 CH 2 -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH 2 O-、-CF 2 O- or -C≡C-, where the asymmetric bridging group can be oriented to both sides, and where there are no adjacent groups, the two O atoms are directly connected,

[0026] Sp 1 represents a single bond or -(CH 2 ) m -, where m = 1, 2, 3 or 4 and one or two of CH 2 The group may be substituted by -O- or -S- in such a way that the O / S atoms are not directly attached to each other,

[0027] Sp 2 represents a straight-chain or branched trivalent spacer group, preferably a trivalent alkylene group having 1 to 10 C atoms, which is straight-chain or branched, wherein one or more non-adjacent CH 2 The group may be replaced by -O-, and the structural part is particularly preferred One of

[0028] A 1 represents independently in each case a group selected from the following group:

[0029] a) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, wherein one or more non-adjacent CH 2 The group may also be replaced by -O- and / or -S-, and one or more H atoms may also be replaced by F or Cl,

[0030] b) 1,4-phenylene, in which one or two CH groups may also be replaced by N, and in which one or more H atoms may also be replaced by a group L or R 2 Alternative, and

[0031] c) the group consisting of 2,6-naphthylene, dibenzofuran-3,7-diyl, dibenzothiophene-3,7-diyl, 9H-fluorene-2,7-diyl, phenanthrene-2,7-diyl, 6H-benzo[c]chromene-3,8-diyl, anthracene-2,6-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, which may also be mono- or polysubstituted by radicals L,

[0032] A 2 represents a 6- or 5-membered saturated, unsaturated or aromatic, carbocyclic or heterocyclic ring system, preferably a cyclohexane ring or a benzene ring, which is optionally additionally substituted in each case by one or two radicals L,

[0033] L independently represents F, Cl, -CN, an alkyl group having 1 to 5 C atoms, an alkoxy group having 1 to 5 C atoms or an alkenyl group having 2 to 5 C atoms,

[0034] and

[0035] n represents 0, 1, 2, 3 or 4, preferably 0, 1, 2 or 3, particularly preferably 1, 2 or 3, very particularly preferably 1 or 2.

[0036] The self-aligning additive for vertical alignment is preferably selected from the formula:

[0037] MES-R a II

[0038] in

[0039] MES is a rod-shaped mesogenic group comprising two or more rings directly or indirectly connected to each other or fused to each other, and the mesogenic group is optionally substituted by one or more polymerizable groups connected to MES directly or through a spacer, and

[0040] R a is a polar anchoring group, which is located at the terminal position of the rod-like group MES, comprises at least one carbon atom and at least one group selected from -OH, -SH, -COOH, -CHO or a primary or secondary amine function, preferably one or two OH groups, and which optionally comprises one or two polymerizable groups P.

[0041] Preferably, the polar anchor group R ais a straight or branched chain alkyl group having 1 to 12 carbon atoms, wherein any CH 2 Optionally -O-, -S-, -CH=CH-, -C≡C-, -NR 0 - or -NH-, and is replaced by one, two or three selected from -OH, -SH, -NH 2 or -NR 0 H is substituted with a polar group, where R 0 is an alkyl group having 1 to 10 carbon atoms. More preferably, R 2 is a group R defined as follows a .

[0042] More preferably, the self-aligning additive for vertical alignment is selected from Formula IIa

[0043] R 1 -[A 2 -Z 2 ] m -A 1 -R a IIa

[0044] in

[0045] A 1 , A 2 each independently of one another represents an aromatic, heteroaromatic, alicyclic or heterocyclic radical which may also contain condensed rings and which may also be mono- or polysubstituted by radicals L or -Sp-P,

[0046] L in each case independently of one another denotes H, F, Cl, Br, I, -CN, -NO 2 ,-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, where in addition one or more H atoms may each be replaced by F or Cl,

[0047] P represents a polymerizable group,

[0048] Sp represents a spacer group or a single bond,

[0049] Z 2 represents, in each case independently of one another, a single bond, -O-, -S-, -CO-, -CO-O-, -OCO-, -O-CO-O-, -OCH 2 -,-CH 2 O-, -SCH2 -,-CH 2 S-, -CF 2 O-, -OCF 2 -, -CF 2 S-, -SCF 2 -,-(CH 2 ) n1 -, -CF 2 CH 2 -,-CH 2 CF 2 -,-(CF 2 ) n1 -, -CH=CH-, -CF=CF-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, -(CR 0 R 00 ) n1 -,-CH(-Sp-P)-,-CH 2 CH-(-Sp-P), or -CH(-Sp-P)CH(-Sp-P)-,

[0050] n1 means 1, 2, 3 or 4,

[0051] m represents 0, 1, 2, 3, 4, 5 or 6,

[0052] R 0 represents in each case independently of one another an alkyl radical having 1 to 12 C atoms,

[0053] R 00 in each case independently of one another represents H or alkyl having 1 to 12 C atoms,

[0054] R 1 independently of one another represent H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, where, in addition, one or more non-adjacent CH 2 groups may 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 may each be replaced by F or Cl, or a -Sp-P group, and

[0055] R a As defined above, preferably refers to a polar anchoring group further defined as having at least one selected from -OH, -NH 2 , -NHR 11 , C(O)OH and -CHO groups, where R 11 represents an alkyl group having 1 to 12 C atoms.

[0056] Anchoring group R of self-aligning additive a More preferably defined as

[0057] The anchoring groups

[0058] p means 1 or 2,

[0059] q means 2 or 3,

[0060] B represents a substituted or unsubstituted ring system or a condensed ring system, preferably selected from benzene, pyridine, cyclohexane, di an alkane or tetrahydropyran ring system,

[0061] Y independently represents O-, -S-, -C(O)-, -C(O)O-, -OC(O)-, -NR 11 - or single key,

[0062] o means 0 or 1,

[0063] X 1 independently represent H, alkyl, fluorinated alkyl, OH, NH 2 , NHR 11 , NR 11 2 , OR 11 , C(O)OH, or -CHO,

[0064] At least one group X 1 It represents a group consisting of -OH, -NH 2 , -NHR 11 , C(O)OH, and -CHO groups,

[0065] R 11 represents an alkyl group having 1 to 12 C atoms,

[0066] Sp a , Sp c , Sp d each independently of one another represents a spacer group or a single bond, and

[0067] Sp b represents a tri- or tetravalent group, preferably CH, N or C.

[0068] Formulae II and IIa optionally include polymerizable compounds. In the present application, "a medium comprising a compound of formula II / IIa" refers to both a medium comprising a compound of formula II / IIa and, alternatively, a medium comprising a polymerized form of said compound.

[0069] In the compounds of formula IIa and its subformulae, Z 1 and Z 2 Preferably represents a single bond, -C2 H 4 -, -CF 2 O- or -CH 2 In a particularly preferred embodiment, Z 1 and Z 2 Each independently represents a single bond.

[0070] In the compounds of the formula IIa, the radical L independently in each case preferably represents F or alkyl, preferably CH 3 , F, C 2 H 5 or C 3 H 7 .

[0071] Preferred compounds of formula II are illustrated by the following sub-formulae II-A to II-D

[0072]

[0073]

[0074]

[0075]

[0076] Where R 1 , R a , A 2 , Z 2 , Sp and P have the meanings defined above for formula IIa,

[0077] L 1 are independently as defined above for L in Formula IIa,

[0078] m is independently 1, 2, 3 or 4, and

[0079] r1 is independently 0, 1, 2, 3, or 4, preferably 0, 1 or 2.

[0080] In the compounds of formula II-A to II-D, L 1 Preferably represents F or alkyl, preferably CH 3 , F, C 2 H 5 or C 3 H 7 .

[0081] In a preferred embodiment, r2 represents 1 and / or r1 represents 0.

[0082] 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.

[0083] In the above and below, in formula IIa or II-A to II-D and their subformulae, Z 1 Preferably, each independently represents a single bond or -CH 2 CH 2 -, and very specifically represents a single bond.

[0084] R a Preferred representation

[0085]

[0086] where p = 1, 2, 3, 4, 5 or 6, and

[0087] R 22 is H, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl or -CH 2 CH 2 -tert-butyl

[0088] Especially -O(CH 2 ) 2 -OH, -O(CH 2 ) 3 -OH,

[0089]

[0090]

[0091] Where R 22 is H, methyl, ethyl, n-propyl, n-butyl or n-pentyl,

[0092]

[0093] In Formula IIa and subformulas of Formula IIa, R 1 Preferably, it represents a straight-chain alkyl group or a branched alkyl group having 1 to 8 C atoms, preferably a straight-chain alkyl group. 1 More preferably, CH 3 , C 2 H 5 , nC 3 H 7 , nC 4 H 9 , nC 5 H 11 , nC 6 H 13 or CH2 CH(C 2 H 5 )C 4 H 9 . R 1 It may also represent alkenyloxy, in particular OCH 2 CH=CH 2 , OCH 2 CH=CHCH 3 , OCH 2 CH=CHC 2 H 5 or alkoxy, especially OC 2 H 5 , O.C. 3 H 7 , O.C. 4 H 9 , O.C. 5 H 11 and OC 6 H 13 R is particularly preferred 1 represents a straight chain alkyl group, preferably C 5 H 11 .

[0094] In formula IIa and in subformulas of formula IIa, the number m is preferably 1, 2, 3 or 4, more preferably 2, 3 or 4. For m=0, ring A 1 Preference is given to ring elements having two or more rings, ie fused ring systems, such as 1,1′-biphenyl or dibenzofuran-3,7-diyl.

[0095] Particularly preferred compounds of formula IIa are compounds selected from sub-formulae II-1 to II-47,

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] Among them, R 1 , L 1 , L2 , Sp, P and R a has the meaning given above for formula II or IIa, and L 3 Such as L 2 Defined. 1 has the meanings given in formula IIa, preferably denotes a straight-chain alkyl radical having 1 to 8 carbon atoms, preferably C 2 H 5 , nC 3 H 7 , nC 4 H 9 , nC 5 H 11 , nC 6 H 13 or nC 7 H 15 , more preferably nC 5 H 11 .

[0105] Preferred LC mixtures according to the invention comprise at least one compound of the formula II, IIa or preferred subformulae thereof.

[0106] Preferred embodiments of the polyfluorinated additive are presented below. 1 represents a compound of the formula I having a straight-chain, unbranched alkyl radical with 1 to 20 C atoms, in which in each case one or more CH 2 The radicals may each independently of one another also be replaced by —CH═CH— or —C≡C—.

[0107] Ring A in Formula I 1 Preferably, independently in each case and in the case of multiple occurrences, represents a radical selected from the subgroups a) and b), which may also be mono- or polysubstituted by radicals L. 1 Particularly preferably it represents a cyclohexane ring, a cyclohexene ring or a benzene ring which is optionally additionally substituted by one or two L radicals.

[0108] The groups L preferably independently represent F, Cl, -CF 3 or an alkyl or alkoxy group having 1, 2 or 3 carbon atoms, particularly preferably F, Cl, methyl or ethyl.

[0109] Group Z 1 Preferably it represents a single bond.

[0110] The compound of formula I is preferably selected from the following compounds

[0111]

[0112]

[0113] Among them, the structures of formula IA, IB, IC, ID and IF are preferred, and the structures of formula IA, IC and IF are particularly preferred.

[0114] Group R F Preferably, it is selected from the formula in particular unit.

[0115] The following fraction for R F Particularly preferred are:

[0116]

[0117] The following formula is very particularly preferred:

[0118]

[0119] Ring A 2 represents a six-membered ring, preferably a benzene ring or a cyclohexane ring.

[0120] R 2 Particularly preferred is the formula The group.

[0121] Group Preferably represents the following group

[0122] Group Preferred representation

[0123] Group R F contains a total of at least 9 fluorine atoms, particularly preferably at least 12 fluorine atoms, also 18 or more, 28 or more and very particularly preferably 36 or more fluorine atoms. 2 The preferred number of fluorine atoms in the group R 2 The total number of fluorine atoms is preferably 60 or less.

[0124] Preference is given to compounds of the formula I and to liquid-crystalline media comprising additives of the formula I in which the radicals of the formula I have one of the preferred meanings indicated.

[0125]

[0126]

[0127] Among them, structures of the formulae I-1 and I-2 are particularly preferred, and structures of the formula I-2 are very particularly preferred.

[0128] In Formulas I and I-1 to I-5, part Preferably represents a moiety selected from the following formulae:

[0129]

[0130]

[0131] wherein the substituents are as defined above and below, the ring is optionally substituted by a group L, and corresponds to ring A in formulae I and I-1 to I-5 2 The right side ring is composed of one or two groups R 2 replaced.

[0132] Therefore, preferably the structure is selected from the following formula:

[0133]

[0134]

[0135] wherein the variables are as defined above and below. Most preferably, compounds of structure 1-2-1 are used as spreading additives.

[0136] The radical R in formula I and its subformulae 1 It preferably denotes an alkyl radical having 1 to 15 C atoms, in particular an alkyl radical having 2 to 6 C atoms. It is preferably an n-alkyl radical.

[0137] The compound according to the present invention is very soluble in the liquid crystal medium commonly used for display devices. The compound improves the wettability of the liquid crystal medium on the substrate and the flow properties on the surface. They especially cause the reduced surface tension, the reduced contact angle of the medium relative to the substrate and the excellent spreadability of the droplets on the surface. They are therefore good spreading agents or wetting agents particularly for liquid crystal media. Suitable substrates are surfaces consisting of glass, ITO (indium tin oxide), polyimide layers (alignment coatings) or a variety of plastics. As far as the compound according to the present invention is concerned as an additive, a stable nematic phase can be easily prepared in a wide temperature range. The ODF drop-down display unevenness and other display unevenness related to spreading are effectively significantly reduced.

[0138] Besides their excellent properties as liquid-crystal components, the compounds according to the invention are also characterized by very little influence on the already optimized physical properties of the medium, such as VHR ('voltage holding ratio'), long-term stability (reliability), low-temperature stability, response time, etc.

[0139] Halogen in the context of the present invention denotes fluorine, chlorine, bromine or iodine, in particular fluorine or chlorine, and very particularly fluorine.

[0140] For example, the following specific individual compounds are particularly preferred:

[0141]

[0142]

[0143] According to the invention, the compounds of formula I are used in a total concentration of 0.001% to 2%, more preferably 0.005% or more to 0.1% or less, particularly preferably 0.01% or more to 0.05% or less.

[0144] 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.

[0145] Aryl and heteroaryl groups can be monocyclic or polycyclic, ie, they can contain one ring (eg, phenyl) or two or more fused rings (eg, naphthyl).

[0146] Particularly preferred are mono-, bi- or tricyclic aryl radicals having 6 to 25 carbon atoms and mono-, bi- or tricyclic heteroaryl radicals having 5 to 25 ring atoms, which optionally contain fused rings and are optionally substituted. Furthermore 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 directly linked to one another.

[0147] Preferred aromatic ring systems (aryl) are, for example, phenyl, naphthyl, anthracene, binaphthyl, phenanthrene, 9,10-dihydrophenanthrene, pyrene, dihydropyrene, Perylene, tetracene, pentacene, benzopyrene, fluorene, indene, indenofluorene, spirobifluorene, etc.

[0148] A preferred unsaturated ring system is cyclohexene-1,4-diyl ring.

[0149] Preferred heterocyclic ring systems are di Alkane-2,5-diyl, tetrahydropyran-2,5-diyl, dibenzofuran-3,7-diyl, thiophene-2,5-diyl or selenophene-2,5-diyl. The heteroaryl group preferably includes, but is not limited to, thiophene-2,5-diyl, dibenzofuran-3,7-diyl, dibenzothiophene-3,7-diyl or selenophene-2,5-diyl.

[0150] The liquid crystal medium according to the invention is preferably polar, i.e. it has a positive or negative dielectric anisotropy. The medium is preferably nematic. More preferably, it has a negative dielectric anisotropy. In this case, it is advantageously suitable for nematic displays of the VA or ECB type.

[0151] The liquid-crystalline medium preferably further comprises a certain proportion of a polymerizable compound, which is preferably selected from the compounds in Table G and compounds of the formula II equipped with a polymerizable group P. The invention is particularly advantageous for polymer-stabilized media and display systems, since imperfect alignment and other defects are reduced, which otherwise become more or less permanent in the polymerization step. The LC medium according to the invention preferably comprises one or more compounds comprising methacrylate groups, acrylate groups or other kinds of acrylate derivative groups, most preferably methacrylate groups.

[0152] As a preferred embodiment, a medium having negative dielectric anisotropy is used and described below, which comprises

[0153] a) one or more compounds of formula III

[0154]

[0155] in

[0156] R 21 represents an unsubstituted alkyl group having 1 to 7 C atoms, an unsubstituted alkoxy group having 1 to 6 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms,

[0157] R 22 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkoxy group having 1 to 6 C atoms,

[0158]

[0159] p and q each independently represent 0, 1 or 2, and

[0160] (p+q) means 1, 2 or 3,

[0161] b) optionally one or more compounds of formula IV

[0162]

[0163] in

[0164] X represents O or S, preferably O, and

[0165] R 31 , R 32 independently of one another represent an unsubstituted alkyl radical having 1 to 7 C atoms, preferably an n-alkyl radical, particularly preferably having 2 to 5 C atoms, or represent an unsubstituted alkoxy radical having 2 to 7 C atoms, particularly preferably having 2 to 5 C atoms,

[0166] Among them, the group R 31 and R 32At least one of represents an alkoxy group,

[0167] and

[0168] c) optionally, preferably necessarily, one or more compounds selected from the group consisting of formulae V and VI, more preferably formula V,

[0169]

[0170] in

[0171] R 41 represents an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably an n-alkyl radical, which particularly preferably has 2, 3, 4 or 5 C atoms, and

[0172] R 42 denotes unsubstituted alkyl having 1 to 7 C atoms or unsubstituted alkoxy having 1 to 6 C atoms, both preferably having 2 to 5 C atoms, unsubstituted alkenyl having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably vinyl or 1-propenyl, and in particular vinyl,

[0173] R 51 and R 52 Independently of each other, they have 21 and R 22 alkyl, preferably n-alkyl, particularly preferably n-alkyl, having 1 to 5 C atoms, alkoxy, preferably n-alkoxy, particularly preferably n-alkoxy, having 1 to 7 C atoms, alkoxyalkyl, alkenyl or alkenyloxy, preferably alkenyloxy, having 2 to 7 C atoms, preferably 2 to 4 C atoms,

[0174] to If present, in each case independently of each other Best

[0175] Preferably,

[0176] express

[0177] and, if present,

[0178] Preferred representation

[0179] Z 51 To Z53 Each independently represents -CH 2 -CH 2 -、-CH 2 -O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH 2 -CH 2 -、-CH 2 -O- or a single bond, and a single bond is particularly preferred,

[0180] i and j each independently represent 0 or 1,

[0181] (i+j) preferably represents 0 or 1.

[0182] The liquid-crystalline media according to the invention preferably comprise one or more compounds of the formula III selected from the formulae III-1 to III-3, preferably III-1 and III-3,

[0183]

[0184] in

[0185] R 21 represents an unsubstituted alkyl radical having 1 to 7 C atoms, preferably an n-alkyl radical, which particularly preferably has 2 to 5 C atoms, or

[0186] unsubstituted alkenyl having 2 to 7 C atoms, preferably straight-chain alkenyl, particularly preferably having 2 to 5 C atoms,

[0187] R 22 represents an unsubstituted alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms, or an unsubstituted alkoxy radical having 1 to 6 C atoms, preferably having 2, 3 or 4 C atoms, and

[0188] m, n and o each independently represent 0 or 1.

[0189] The medium according to the invention preferably comprises one or more compounds selected from the formulae III-1 to III-3 in a total concentration of 10% or more to 80% or less, preferably 15% or more to 70% or less, particularly preferably 20% or more to 60% or less.

[0190] In another preferred embodiment, the medium according to the present invention, in addition to the compounds selected from formulae III-1 to III-3, also contains one or more compounds of formula IV-1 in a total concentration of 1% or more to 20% or less, preferably 2% or more to 15% or less, particularly preferably 3% or more to 10% or less.

[0191] The medium according to the invention, in addition to the compound of formula III or its preferred subformulae, preferably also contains one or more dielectrically neutral compounds of formula V in a total concentration of 5% or more to 90% or less, preferably 10% or more to 80% or less, particularly preferably 20% or more to 70% or less.

[0192] In a preferred embodiment of the present invention, the medium according to the invention comprises one or more compounds of the formula III-1, preferably one or more compounds selected from the group consisting of compounds of the formulae III-1-1 and III-1-2

[0193]

[0194] wherein the parameters have the meanings given above in the case of formula III-1, and preferably

[0195] R 21 represents an alkyl group having 2 to 5 C atoms, preferably having 3 to 5 C atoms, and

[0196] R 22 represents an alkyl or alkoxy group having 2 to 5 C atoms, preferably an alkoxy group having 2 to 4 C atoms, or an alkenyloxy group having 2 to 4 C atoms.

[0197] In a preferred embodiment of the present invention, the medium according to the invention comprises one or more compounds of the formula III-2, preferably one or more compounds selected from the group consisting of compounds of the formulae III-2-1 and III-2-2

[0198]

[0199] wherein the parameters have the meanings given above in the case of formula III-2, and preferably

[0200] R 21 represents an alkyl group having 2 to 5 C atoms, preferably having 3 to 5 C atoms, and

[0201] R 22 represents an alkyl or alkoxy group having 2 to 5 C atoms, preferably an alkoxy group having 2 to 4 C atoms, or an alkenyloxy group having 2 to 4 C atoms.

[0202] In a particularly preferred embodiment of the present invention, the medium according to the invention comprises one or more compounds of the formula III-3, preferably one or more compounds selected from the group consisting of compounds of the formulae III-3-1 and III-3-2, very particularly preferably compounds of the formula III-3-2,

[0203]

[0204] wherein the parameters have the meanings given above in the case of formula III-3, and preferably

[0205] R 21 represents an alkyl group having 2 to 5 C atoms, preferably having 3 to 5 C atoms, and

[0206] R 22 represents an alkyl or alkoxy group having 2 to 5 C atoms, preferably an alkoxy group having 2 to 4 C atoms, or an alkenyloxy group having 2 to 4 C atoms.

[0207] In another preferred embodiment, the medium comprises one or more compounds of formula IV-1 to IV-3

[0208]

[0209] in

[0210] Alkyl, Alkyl' denotes an alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0211] Alkoxy, Alkoxy′ denotes alkoxy having 1 to 7 C atoms, preferably having 2 to 5 C atoms.

[0212] The medium particularly preferably comprises one or more compounds of the formula IV-1.

[0213] In another preferred embodiment, the medium comprises one or more compounds of formula V

[0214]

[0215] in

[0216] R 41 represents an unsubstituted alkyl radical having 1 to 7 C atoms or an unsubstituted alkenyl radical having 2 to 7 C atoms, preferably an n-alkyl radical, which particularly preferably has 2, 3, 4 or 5 C atoms, and

[0217] R 42 represents unsubstituted alkyl having 1 to 7 C atoms or unsubstituted alkoxy having 1 to 6 C atoms, both preferably having 2 to 5 C atoms, unsubstituted alkenyl having 2 to 7 C atoms, preferably having 2, 3 or 4 C atoms, more preferably vinyl or 1-propenyl, and in particular vinyl.

[0218] In a particularly preferred embodiment, the medium comprises one or more compounds of the formula V selected from the compounds of the formulae V-1 to V-4, preferably selected from the compounds of the formulae V-1 and V-2,

[0219]

[0220]

[0221] Alkyl and Alkyl′ independently of one another denote an alkyl radical having 1 to 7 C atoms, preferably having 2 to 5 C atoms,

[0222] Alkenyl is an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably 2 C atoms,

[0223] Alkenyl′ denotes an alkenyl radical having 2 to 5 C atoms, preferably having 2 to 4 C atoms, particularly preferably having 2 to 3 C atoms, and

[0224] Alkoxy is an alkoxy group having 1 to 5 C atoms, preferably having 2 to 4 C atoms.

[0225] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds of the formula V-1 and / or one or more compounds of the formula V-2.

[0226] In another preferred embodiment, the medium comprises one or more compounds of formula VI

[0227]

[0228] in

[0229] R 51 and R 52 Independently of each other, they have 21 and R 22 alkyl, preferably n-alkyl, particularly preferably n-alkyl, having 1 to 5 C atoms, alkoxy, preferably n-alkoxy, particularly preferably n-alkoxy, having 1 to 7 C atoms, alkoxyalkyl, alkenyl or alkenyloxy, preferably alkenyloxy, having 2 to 7 C atoms, preferably 2 to 4 C atoms,

[0230] to If present, in each case independently of each other Best

[0231] Preferably

[0232] express

[0233] and, if present,

[0234] Preferred representation

[0235] Z 51 To Z 53 Each independently represents -CH 2 -CH 2 -、-CH 2 -O-, -CH=CH-, -C≡C-, -COO- or a single bond, preferably -CH 2 -CH 2 -、-CH 2 -O- or a single bond and particularly preferably a single bond,

[0236] i and j each independently represent 0 or 1,

[0237] (i+j) preferably represents 0 or 1.

[0238] The medium according to the invention preferably comprises the following compounds in the indicated total concentrations:

[0239] 5-60% by weight of one or more compounds selected from the compounds of formula III, and / or

[0240] 5-60% by weight of one or more compounds selected from the group consisting of compounds of formula III and IV, and / or

[0241] 10-60% by weight of one or more compounds selected from the compounds of formulae III-1 to III-3, and / or

[0242] 10-60% by weight of one or more compounds of formula V and / or VI,

[0243] The total content of all compounds in the medium is 100%.

[0244] As a preferred embodiment, a medium having positive dielectric anisotropy is described below, which comprises

[0245] One or more compounds of formula VII and VIII:

[0246]

[0247] in

[0248] R 0 represents an alkyl or alkoxy radical having 1 to 15 C atoms, wherein in addition, one or more CH 2 The groups may be optionally and independently of each other replaced by -C≡C-, -CF 2 O-, -CH=CH-, -O-, -(CO)-O- or -O(CO)- are replaced in such a way that the O atoms are not directly connected to one another, and wherein in addition, one or more H atoms may optionally be replaced by halogen,

[0249] Ring A represents

[0250] Ring B independently represents 1,4-phenylene, which is optionally substituted by one or two F or Cl,

[0251] X 0 Indicates F, Cl, CN, SF 5 , SCN, NCS, a haloalkyl group, a haloalkenyl group, a haloalkoxy group or a haloalkenyloxy group, which has in each case up to 6 C atoms,

[0252] Y 1-4 Each independently represents H or F,

[0253] Z 0 Indicates -CF 2 O-, -(CO)O- or a single bond, and

[0254] c represents 0, 1 or 2, preferably 1 or 2,

[0255] and

[0256] c) Optionally, preferably necessarily, one or more compounds selected from the group consisting of formula V and VI provided above, preferably formula V.

[0257] Some groups

[0258] Preferred representation

[0259]

[0260] R 0 preferably represents a straight-chain alkyl or alkenyl group having 2 to 7 C atoms;

[0261] X 0 Preferred representation: F, OCF 3 , Cl or CF 3 , especially F.

[0262] In another embodiment, preference is given to media with positive or negative dielectric anisotropy which comprise both dielectrically negative compounds selected from the group consisting of the formulae III and IV and additionally dielectrically positive compounds selected from the group consisting of the formulae VII and VIII. Dielectrically neutral compounds are also optionally present.

[0263] Quite generally, the combinations and examples of preferred embodiments of the invention given above and below are also to be regarded as particularly preferred, as long as they can be formally combined with one another. Further embodiments can be derived from the claims and their combinations.

[0264] The compounds of the formulae I to VIII are prepared by methods known per se, as described in the literature (e.g. in standard works, such as Houben-Weyl, Methoden der Organischen Chemie (Methods of Organic Chemistry), Georg-Thieme-Verlag, Stuttgart), more precisely under reaction conditions known and suitable for the reactions described. It is also possible to use variants known per se which are not mentioned in greater detail here. The compounds of the formula I can advantageously be prepared as can be seen from the synthesis illustrated below (Scheme 1).

[0265] A typical preparation method of a series of compounds according to the present invention comprises the following process steps, in which a polyfluorinated alcohol (e.g. C(CF 3 ) 3 OH) is etherified with another OH-functionalized compound having one or more ring systems (Scheme 1). The process is preferably condensed under Mitsunobu conditions. It is therefore preferably carried out in the presence of triphenylphosphine and an azodicarboxylic acid ester (e.g. DIAD, DEAD), preferably with diisopropyl azodicarboxylate. The reaction is typically carried out in THF at 20-50° C.

[0266]

[0267] Scheme 1. Exemplary preparation of compounds of formula I from polyfluorinated alcohols via ether formation.

[0268] A typical preparation method of another series of compounds according to the present invention comprises the following process steps, in which a polyfluorinated alkene (e.g. F 2 C=C(CF 3 ) 2 ) is linked to a halogenated (electrophilic) compound via a CC bond (Scheme 2).

[0269]

[0270] Scheme 2. Exemplary preparation of compounds of formula I via CC coupling from polyfluorinated nucleophiles.

[0271] As an exemplary reaction, the reaction according to Scheme 3 is shown, in which a perfluoroalkene is activated with the aid of cesium fluoride to give a carbanion and is linked to a benzyl bromide (see, for example, KN Makarov et al., Journal of Fluorine Chemistry, 10 (1977) 157-158).

[0272]

[0273] Scheme 3. Exemplary synthesis of additives without ether linkage

[0274] Suitable polyfluorinated starting materials (alcohols, alkenes) are commercially available. According to the structure R shown in Scheme 1 as a starting material 1 -[A 1 -Z 1 ] n -Sp 1 -OH or R 1 -[A 1 -Z 1 ] n -Sp 1 -(OH) 2 The alcohols are known in the literature or can be obtained analogously thereto, as are the analogous halide compounds according to Scheme 2.

[0275] The substituents of the compounds in Scheme 1 can be varied analogously to the general formula I by changing the building blocks used. In this way, very different compounds according to the invention are obtained.

[0276] The compounds of formula I are suitable for VA-TFT display systems of the SA-VA type and other self-aligned vertically aligned display systems. The person skilled in the art is familiar with further display types in which the combinations of additives of formulae I and II according to the invention can be advantageously used for vertically aligned displays in liquid crystal media.

[0277] The invention also provides an electro-optical display or electro-optical component containing a liquid-crystalline medium according to the invention.Preference is given to electro-optical displays based on the VA or ECB effect, and in particular those which are addressed by means of an active-matrix addressing device.

[0278] The present invention therefore likewise relates to the use of the liquid-crystalline media according to the invention in electro-optical displays or in electro-optical components.

[0279] The present invention likewise relates to a process for preparing a liquid-crystalline medium as described above and below, characterized in that one or more compounds of the formula I and II are mixed with one or more liquid-crystalline compounds and optionally further compounds and additives are added. Preference is given to a process for preparing a liquid-crystalline medium according to the invention, characterized in that one or more compounds of the formula I and II are mixed with one or more compounds of the formula III and with one or more further liquid-crystalline compounds and / or additives.

[0280] In the present application, the term "compound", which is also written as "one or more compounds", means both one compound and a plurality of compounds, unless explicitly stated otherwise.

[0281] In this application:

[0282] -alkyl particularly preferably denotes straight-chain alkyl, in particular CH 3 -、C 2 H 5 -、nC 3 H 7 、nC 4 H 9 - or nC 5 H 11 -,

[0283] -Alkenyl particularly preferably represents CH 2 =CH-, E-CH 3 -CH=CH-, CH 2 =CH-CH 2 -CH 2 -、E-CH 3 -CH=CH-CH 2 -CH 2 - or E-(nC 3 H 7 )-CH=CH-,

[0284] -alkoxy particularly preferably denotes straight-chain alkoxy, in particular CH 3 O-、C 2 H 5 O-、nC 3 H 7 O-、nC 4 H 9 O- or nC 5 H 11 O-.

[0285] For the present invention, the formula represents trans-1,4-cyclohexylene, and the subformula It represents 1,4-phenylene.

[0286] In the present application, the term "dielectrically positive" describes a compound or component with Δε>3.0, "dielectrically neutral" describes a compound or component with -1.5≤Δε≤3.0, and "dielectrically negative" describes a compound or component with Δε<-1.5. Δε is measured at a frequency of 1 kHz and at 20°C. The dielectric anisotropy of the corresponding compound is determined by the results of a 10% solution of the corresponding single compound in a nematic host mixture. If the solubility of the corresponding compound in the host mixture is less than 10%, the concentration is reduced to 5%. The capacitance of the test mixture is measured both in a liquid crystal cell with homeotropic alignment and in a liquid crystal cell with planar alignment. The cell thickness of these two liquid crystal cell types is about 20 μm. The applied voltage is a rectangular wave with a frequency of 1 kHz and an effective value of typically 0.5 V to 1.0 V, which is however always selected so that it is below the capacitance threshold of the corresponding test mixture.

[0287] Δε is defined as (ε || -ε ⊥ ), and ε 平均 Yes (ε || +2ε ⊥ ) / 3.

[0288] The host mixture for dielectrically positive compounds was mixture ZLI-4792, and the host mixture for dielectrically neutral and dielectrically negative compounds was mixture ZLI-3086, both from Merck KGaA, Germany. The absolute values ​​of the dielectric constants of the compounds were determined from the changes in the corresponding values ​​of the host mixtures when the compounds of interest were added. The values ​​were extrapolated to a concentration of 100% of the compounds of interest.

[0289] Components having a nematic phase at a measurement temperature of 20° C. were measured as they were, and all other substances were treated as compounds.

[0290] In both cases, unless otherwise expressly stated, the term "threshold voltage" in this application means the optical threshold and is the value for a 10% relative contrast ratio (V 10 ) indicates that the term "saturation voltage" refers to the optical saturation and is the value for 90% relative contrast (V 90 ) is also known as the Freedericks threshold V Fr The capacitance threshold voltage (V 0 ) is used only if it is explicitly mentioned.

[0291] The parameter ranges indicated in this application all include the limiting values, unless expressly indicated otherwise.

[0292] The different upper and lower value limits indicated for the various ranges of properties in combination with one another give rise to further preferred ranges.

[0293] Throughout the present application, the following conditions and definitions apply, unless expressly stated otherwise. All concentrations are stated in % by weight and in each case based on the entire mixture, all temperatures and all temperature differences are stated in degrees Celsius or differential degrees. All physical properties are determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", November 1997, Merck KGaA, Germany, and are quoted for a temperature of 20°C, unless expressly stated otherwise. The optical anisotropy (Δn) is determined at a wavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined at a frequency of 1 kHz. The threshold voltage and all other electro-optical properties are determined in a test box prepared by Merck. The test box for determining Δε has a box thickness of about 20 μm. The electrodes are 1.13 cm 2 The alignment layer, for the homeotropic alignment (ε || ), SE-1211 from Nissan Chemicals, Japan, and for the surface alignment (ε ⊥ ), is polyimide AL-1054 obtained from Japan Synthetic Rubber, Japan. The capacitance was measured using a Solatron 1260 frequency response analyzer using a 0.3V rms The light used in the electro-optical measurements is white light. Here, a device with a DMS instrument commercially available from the company Autronic-Melchers, Germany, is used. The characteristic voltage is determined under perpendicular observation. The threshold voltage (V 10 ), “mid-grey voltage” (V 50 ) and saturation voltage (V 90 ) are measured for 10%, 50% and 90% relative contrast, respectively.

[0294] The liquid crystal media according to the invention may contain further additives and chiral dopants in the usual concentrations. The total concentration of these further ingredients is in the range of 0% to 10%, preferably 0.1% to 6%, based on the overall mixture. The concentration of the individual compounds used is preferably in the range of 0.1% to 3% in each case. When quoting values ​​and concentration ranges for liquid crystal components and compounds in the liquid crystal media in the present application, the concentrations of these and similar additives are not taken into account.

[0295] The liquid crystal medium according to the invention consists of a plurality of compounds, preferably 3 to 30, more preferably 4 to 20, and very preferably 4 to 16 compounds. These compounds are mixed in a conventional manner. Usually, the required amount of the compound used in a smaller amount is dissolved in the compound used in a larger amount. If the temperature is above the clearing point of the compound used in a higher concentration, the completion of the dissolution process is particularly easy to observe. However, the medium can also be prepared by other conventional routes, for example using so-called premixes, which can be, for example, homologous or eutectic mixtures of compounds, or using a so-called "multi-bottle" system, the components of which are themselves ready-to-use mixtures.

[0296] By adding suitable additives, the LC media according to the invention can be modified so that they can be used in all known types of LC displays using homeotropic alignment or tilted-homeotropic alignment.

[0297] All temperatures, such as the melting point T(C,N) or T(C,S) of the liquid crystal, the transition point T(S,N) from the smectic (S) to the nematic (N) phase and the clearing point T(N,I), are given in degrees Celsius. All temperature differences are given in differential degrees.

[0298] In the present invention and in particular in the following examples, the structures of the mesogenic compounds are indicated with the aid of abbreviations, also known as acronyms. In these acronyms, the chemical formulae are abbreviated as described below using the following Tables A to C. All radicals 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, in each case respectively have n, m or 1 C atom.Table A shows the coding of the ring elements for the core structure of the compound, and Table B shows the linking group.Table C gives the meaning of the coding for the end group on the left hand or right hand side.Described acronym is by the coding for the ring elements with optional linking group, then connects the first hyphen, and the coding for the left hand end group, and the second hyphen and the coding for the right hand end group form.Table D compiles the exemplary structure of the compound with its respective abbreviation.

[0299] Table A: Ring elements

[0300]

[0301]

[0302]

[0303] Table B: Linking Groups

[0304]

[0305]

[0306] Table C: End Groups

[0307]

[0308]

[0309]

[0310] wherein n and m are each integers, and the three dots "..." are placeholders for other abbreviations taken from the table.

[0311] The following table shows exemplary structures together with their respective abbreviations. These are shown in order to demonstrate the regular meaning of the abbreviations. The mixtures according to the invention preferably contain, in addition to the compounds of formula I, one or more of the compounds mentioned below.

[0312] The following abbreviations are used:

[0313] (n, m and z each independently represent an integer, preferably 1 to 6).

[0314] Table D: Example Structure

[0315]

[0316]

[0317]

[0318]

[0319]

[0320]

[0321]

[0322]

[0323]

[0324]

[0325]

[0326]

[0327]

[0328]

[0329]

[0330]

[0331]

[0332]

[0333]

[0334]

[0335]

[0336]

[0337]

[0338] Table E below shows chiral dopants which can preferably be used in the mixtures according to the invention.

[0339] Table E

[0340]

[0341]

[0342]

[0343] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds selected from the compounds from Table E.

[0344] Table F shows stabilizers which can be used in the mixtures according to the invention. Here, the parameter n represents an integer in the range from 1 to 12.

[0345] Table F

[0346]

[0347]

[0348]

[0349]

[0350]

[0351]

[0352] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds selected from the compounds from Table F, in particular one or more compounds selected from the compounds of the following two formulae

[0353]

[0354] Table G

[0355] Table G lists exemplary compounds which can be preferably used as polymerisable compounds in the LC media according to the invention.

[0356]

[0357]

[0358]

[0359]

[0360]

[0361]

[0362]

[0363]

[0364]

[0365]

[0366]

[0367]

[0368]

[0369]

[0370]

[0371]

[0372]

[0373]

[0374] In a preferred embodiment of the present invention, the mesogenic medium comprises one or more compounds selected from the compounds from Table G.

[0375] Brief description of the drawings:

[0376] Figure 1 Represents images of two filled LC test cells observed between crossed polarizers (initial alignment images). The black areas represent the homeotropic alignment areas of the cell. The cell on the right is filled according to Example 1 with a polyfluorinated additive, the cell on the left contains a reference sample without a polyfluorinated additive.

[0377] Figure 2 express Figure 1 The cell on the right is filled according to Example 2 with a polyfluorinated additive, and the cell on the left contains a reference sample without a polyfluorinated additive. Example

[0378] The following examples are intended to illustrate the invention without limiting it. Above and below, percentage data represent weight percentages. All temperatures are given in degrees Celsius. In addition, C = crystalline state, N = nematic phase, Sm = smectic phase and I = isotropic phase. The data between these symbols represent transition temperatures. Δn represents optical anisotropy (589 nm, 20° C.), Δε represents dielectric anisotropy (1 kHz, 20° C.) and γ 1 It represents the rotational viscosity (in mPa·s).

[0379] The physical, physicochemical or electro-optical parameters are determined by generally known methods, as described in particular in the brochure "Merck Liquid Crystals - -Physical Properties of Liquid Crystals-Description of the Measurement Methods(Merck Liquid Crystals - Physical properties of liquid crystals - Description of the measurement methods)", 1998, Merck KGaA, Darmstadt.

[0380] In the above and below, Δn represents optical anisotropy (589 nm, 20° C.) and Δε represents dielectric anisotropy (1 kHz, 20° C.). The dielectric anisotropy Δε is measured at 20° C. and 1 kHz. The optical anisotropy Δn is measured at 20° C. and a wavelength of 589.3 nm.

[0381] The Δε and Δn values ​​and the rotational viscosity (γ 1 ) is obtained by mixing 5 to 10% of each compound according to the present invention and 90-95% of a commercially available liquid crystal mixture ZLI-4792 (for Δε>1, Δn, γ 1 The results are obtained by linear extrapolation of a liquid crystal mixture composed of ZLI-2857 (for Δε<1) (mixture, Merck KGaA, Darmstadt).

[0382] Synthesis Example:

[0383] Synthesis Example 1:

[0384]

[0385] 1c: Diisopropyl azodicarboxylate (4.70 ml, 23.9 mmol) was added dropwise to a solution of 1a (5.00 g, 20.3 mmol), 1b (5.53 g, 20.3 mmol) and triphenylphosphine (6.04 g, 23.0 mmol) in 50 ml of anhydrous tetrahydrofuran (THF), during which the reaction temperature was kept below 30° C. The reaction mixture was stirred at room temperature overnight. After the solvent was stripped off, the oily residue was purified by flash chromatography on silica gel with heptane / ethyl acetate to give 1c (5.8 g) as a colorless oil.

[0386] 1d: Palladium (5%) on activated carbon (2.5 g) was added to a solution of 1c (5.2 g, 10.4 mmol) in 50 ml THF and the mixture was hydrogenated under hydrogen for 19 hours. The catalyst was filtered off. After the solvent was removed, the residue was purified by flash chromatography on silica gel with dichloromethane / methanol. 1d (2.6 g) was obtained as a white solid.

[0387] 1: Diisopropyl azodicarboxylate (1.87 ml, 9.6 mmol) was added dropwise to a solution of 1d (1.03 g, 3.2 mmol) and triphenylphosphine (2.52 g, 9.6 mmol) in 25 ml of anhydrous THF at 0°C. After the mixture was stirred for 30 minutes, perfluorotert-butyl alcohol (2.27 g, 9.6 mmol) was added and the mixture was stirred overnight at 45°C. After the solvent was separated and removed, the residue was purified by flash chromatography on silica gel with heptane / ethyl acetate. 1 (1.0 g, mp 41°C) was obtained as white crystals.

[0388] Synthesis Example 2:

[0389]

[0390] 2c: Diisopropyl azodicarboxylate (3.70 ml, 18.8 mmol) was added dropwise to a solution of 2a (2.50 g, 13.5 mmol), 2b (7.60 g, 27.0 mmol) and triphenylphosphine (8.00 g, 30.0 mmol) in 60 ml THF, during which the reaction temperature was kept below 30 ° C. The reaction mixture was stirred at room temperature overnight. After the solvent was separated and removed, the oily residue was purified by flash chromatography on silica gel with heptane / ethyl acetate. 2d (2.1 g) was obtained as a colorless oil.

[0391] 2d: Sodium carbonate (0.9 g, 8.5 mmol) and 4 ml of distilled water were added to a solution of 2c (2.00 g, 2.9 mmol) and 4-pentylphenylboronic acid (0.60 g, 3.1 mmol) in 20 ml of 1,4-dioxane. After the mixture was degassed with argon, [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (0.063 g, 0.09 mmol) was added. The reaction mixture was heated until reflux and stirred overnight. After conventional post-treatment, the collected organic phase was dried over sodium sulfate. After removal of the solvent, the residue was purified by flash chromatography on silica gel with heptane / ethyl acetate. 2d (2.0 g) was obtained.

[0392] 2e: Palladium (5%) on activated carbon (0.5 g) was added to a solution of 2d (2.0 g, 2.6 mmol) in 20 ml THF, and the mixture was hydrogenated under hydrogen for 16 hours. The catalyst was filtered off. After removing the solvent, the residue was purified by flash chromatography on silica gel with dichloromethane / methanol. 2e (1.0 g) was obtained as a colorless oil.

[0393] 2: Diisopropyl azodicarboxylate (2.43 ml, 12.4 mmol) was added dropwise to a solution of 2e (1.0 g, 2.5 mmol) and triphenylphosphine (2.72 ml, 12.4 mmol) in 50 ml of anhydrous THF at 0°C. After the mixture was stirred for 30 minutes, perfluorotert-butyl alcohol (3.5 g, 14.8 mmol) was added and the mixture was stirred overnight at 45°C. After the solvent was separated and removed, the residue was purified by flash chromatography on silica gel with heptane / ethyl acetate. The crude product obtained was recrystallized from ethanol to give product 2 (1.0 g, mp 46°C) as white crystals.

[0394] The following substances were prepared similarly to Examples 1 or 2:

[0395] Synthesis Example 3:

[0396]

[0397] Melting point 65°C (C 65 I).

[0398] Synthesis Example 4:

[0399]

[0400] Synthesis Example 5:

[0401]

[0402] Melting point 40℃(C 40SmA(23)I)

[0403] Synthesis Example 6:

[0404]

[0405] Melting point 36℃(C 36 I)

[0406] Synthesis Example 7:

[0407]

[0408] A mixture of isomers prepared by catalytic hydrogenation of the product obtained in Synthesis Example 2. Oil (main fraction: Tg-38°C I)

[0409] Synthesis Example 8:

[0410]

[0411] Oil (Tg-19℃I)

[0412] Synthesis Example 9:

[0413]

[0414] Synthesis Example 10:

[0415]

[0416] Synthesis Example 11:

[0417]

[0418] Synthesis Example 12:

[0419]

[0420] Synthesis Example 13:

[0421]

[0422] Synthesis Example 14:

[0423]

[0424] Oil.

[0425] 1 H NMR (500MHz, chloroform-d) δ7.55-7.41(m,2H),7.27(dd,J=7.7,5.9Hz,2H),6.84(d,J=2.2Hz,2H),6.56(t,J=2.2Hz,1H),4.59(p,J=4.8Hz ,2H),4.15-3.97(m,8H),3.95-3.85(m,8H),2.67(dd,J=8.7,6.9Hz,2H),1.74-1.63(m,2H),1.46-1.34(m,4H),0.97-0.87(m,3H).

[0426] Synthesis Example 15:

[0427]

[0428] Synthesis Example 16:

[0429]

[0430] Synthesis Example 17:

[0431]

[0432] Oil.

[0433] 1H NMR (chloroform-d) δ7.55-7.45(m,2H),7.27(dd,J=7.6,5.8Hz,2H),6.77(d,J=2.2Hz,2H),6.45(t,J=2.2Hz,1H),6.04(dt,J=54.4,3.8Hz,2H ), 4.27(t,J=6.5Hz,4H), 3.32(t,J=6.4Hz,4H), 2.71-2.61(m,2H), 1.73-1.62(m,2H), 1.46-1.20(m,4H), 0.93(td,J=6.7,4.3Hz,3H).

[0434] Synthesis Example 18:

[0435]

[0436] Oil.

[0437] 1 H NMR (chloroform-d) δ7.43-7.34(m,2H),7.17(dd,J=9.0,7.1Hz,2H),6.67(d,J=2.1Hz,2H),6.39(t,J=2.2Hz,1H),4.51(pd,J= 6.2,4.5Hz,2H),3.98(t,J=13.7Hz,4H),3.70(qd,J=10.5,5.0Hz,4H),2.63-2.52(m,2H),1.65-1.50(m,2H),1.28(app t,J=6.8Hz,10H),0.88-0.79(m,3H).

[0438] Synthesis Example 19:

[0439]

[0440] Oil.

[0441] 1 H NMR (chloroform-d) δ 7.51-7.40 (m, 2H), 7.27 (d, J = 8.0 Hz, 2H), 6.80 (d, J = 2.1 Hz, 2H), 6.48 (t, J = 2.3 Hz, 1H), 4.56 (p, J = 4.8 Hz, 2H), 4.18-4.04 (m, 8H), 3.93-3.81 (m, 8H), 2.73-2.62 (m, 2H), 1.72-1.61 (m, 2H), 1.44-1.33 (m, 4H), 0.97-0.86 (m, 3H).

[0442] Synthesis Example 20:

[0443]

[0444] Oil

[0445] 1 H NMR(chloroform-d)δ7.02(d,J=8.3Hz,2H),6.82-6.74(m,2H),4.41(p,J=4.9Hz,1H),3.94(h,J=12.9Hz,4H), 3.83-3.73(m,4H),2.52-2.43(m,2H),1.57-1.45(m,2H),1.31-1.13(m,12H),0.81(t,J=6.8Hz,3H).

[0446] Synthesis Example 21:

[0447]

[0448] Melting point 92°C (C 92 I).

[0449] Mixture Example: Liquid crystal medium with additives

[0450] The following additives were added to the liquid crystal medium:

[0451] Additive No. Structure of Additive

[0452] Additive No. Structure of Additive

[0453]

[0454] Additive No. Structure of Additive

[0455]

[0456] Mixture Example:

[0457] Use the following alignment additives:

[0458] (As described in EP 2918658 or prepared similarly)

[0459]

[0460]

[0461]

[0462] The following polymerizable compounds were used:

[0463]

[0464] The base mixtures (hosts) used were the following liquid-crystalline media H1 to H10 (data in % by weight).

[0465] H1: Nematic host mixture (Δε<0)

[0466]

[0467] H2: Nematic host mixture (Δε<0)

[0468]

[0469]

[0470] H3: Nematic host mixture (Δε<0)

[0471]

[0472] H4: Nematic host mixture (Δε<0)

[0473]

[0474]

[0475] H5: Nematic host mixture (Δε<0)

[0476]

[0477] H6: Nematic host mixture (Δε<0)

[0478] Main body H1 98.85%

[0479] RM-1 0.35%

[0480] H7: Nematic host mixture (Δε<0)

[0481] Main body H2 98.95%

[0482] RM-1 0.25%

[0483] H8: Nematic host mixture (Δε<0)

[0484] Main body H3 98.85%

[0485] RM-1 0.35%

[0486] H9: Nematic host mixture (Δε<0)

[0487] Body H4 98.85%

[0488] RM-1 0.35%

[0489] H10: Nematic host mixture (Δε<0)

[0490] Main body H5 99%

[0491] RM-1 0.2%

[0492] Various weight percentages of the exemplary additives and one or two alignment additives were added to the LC host mixture and then studied for various parameters (alignment, drop-type display unevenness, reliability).

[0493] For example, spreading additives No. 1 to 5 are added to these media H1 to H10 at a percentage of about 0.025 (±0.01) wt %, and one or more aligning additives II-A to II-K are added at an amount of about 0.5 (±0.3) wt %.

[0494] Test sample results

[0495] Table 1. Composition of the mixture examples (additives in wt %, LC host mixture accounts for the remaining percentage)

[0496]

[0497]

[0498] The manufacturing process of the test kit is

[0499] 1) Adding the polyfluorinated additive to the SA-VA LC mixture,

[0500] 2) Dispensing the LC mixture and sealant onto the substrate,

[0501] 3) Assemble the liquid crystal box,

[0502] 4) Sealant curing;

[0503] 5) PS-VA first and second UV process,

[0504] 6) Initial alignment confirmation and other evaluations.

[0505] To confirm the initial alignment, high quality cell images were collected using a DSLR camera (Nikon).

[0506] The results of Example 1 are provided in Figure 1 The initial alignment of the test cell was significantly improved in the edge region.

[0507] The results of Example 2 are provided in Figure 2 The initial alignment of the test cell was significantly improved in the edge region.

[0508] Overall, the additives of formula I improve the initial alignment.

[0509] Evaluation of ODF display unevenness

[0510] The ODF test enables the evaluation of additives under actual process conditions and shows whether the actually occurring ODF display irregularities can also be improved. The ODF test consists of a series of sub-processes.

[0511] a) Preparation of test display

[0512] Clean the substrate before further processing, whereby all adhering particles should be removed. This is carried out by machine in a multi-step process, where rinsing is carried out stepwise with a soap solution (distilled water and 0.5% detergent) and pure distilled water. After completion of the rinsing operation, the substrate is dried at 120°C for 30 minutes.

[0513] Adhesive was then applied at the edges of the substrates (Sekisui) and the LC medium was applied dropwise (ODF) onto the substrates. The lower substrate with the adhesive and the LC medium was brought together with the upper substrate with ITO and photo-spacer (3.3 μm) by means of vacuum (5 Pa, 30 sec). The test display was then bonded by means of UV light (wherein only the adhesive edges were exposed) and a heating step was performed (according to the adhesive manufacturer's instructions).

[0514] The PS-VA process is then carried out to achieve the pre-tilt angle. For this purpose, a DC voltage of about 10 V is applied to the box under UV irradiation. The UV irradiation triggers the photopolymerization of the RMs. The desired tilt angle is adjusted via the RM concentration, the irradiation intensity, the irradiation duration or the strength of the applied field. When the desired pre-tilt angle is reached, the process is terminated. A second UV step is then carried out without voltage to remove the residual RMs.

[0515] b) Evaluation of uneven display of dripping type

[0516] ODF display heterogeneity can be described by visual inspection and alternatively by measuring the tilt angle in different areas.

[0517] Tilt measurement:

[0518] The pretilt angle was measured with positional resolution by means of a Mueller matrix polarimeter (Axometrics Axostep) in the area where the droplet was located before spreading during the vacuum treatment and in an area where no LC medium was placed before the treatment. The difference is a criterion for describing the ODF level. The smaller the difference, the less ODF display unevenness occurs.

[0519] The test display was operated for backlight at various grayscales (various drive voltages). With the aid of a DSLR camera, images of the display were recorded and analyzed with the aid of software. The grayscale was determined with the aid of electro-optical curves (transmittance versus voltage). For this purpose an LCD-5200 (Otsuka, JP) was used.

[0520] c) Results

[0521] Table 2. Results of ODF display unevenness

[0522] Mixture Example 1 Mixture Example 2 ODF dripping type shows unevenness none none

[0523] The media according to the invention show no visible drip-like unevenness.

[0524] Mixture Examples 3 to 6

[0525] Table 2. Composition of the mixture examples (additives in wt %, LC host mixture accounts for the remaining percentage)

[0526]

[0527]

[0528] Table 3. Composition of the mixture examples (additives in wt %, LC host mixture accounts for the remaining percentage)

[0529]

Claims

1. A liquid crystal medium comprising a liquid crystal component, characterized in that The liquid crystal medium comprises one or more self-aligning additives for homeotropic alignment and one or more compounds of the following formula I, wherein the total concentration of the compounds of formula I in the entire medium is from 0.001% by weight or more to 2% by weight or less: in R 1 represents a straight-chain or branched alkyl group having 1 to 20 C atoms or H, wherein in this group one or more CH2 groups can also be each independently of one another replaced by -C≡C-, -CH=CH-, -O-, -S-, -CO-O- or -O-CO- is replaced in such a way that the O or S atoms are not directly attached to each other, R F Indicates the selected formula The group, R 2 In each case independently R 1 , Rf 3 independently represent H, F, -CF3, -CF2CF3, -CF2CF2CF3 or CF(CF3)2, R 2 independently represent an unbranched, branched or cyclic fluoroalkyl group having 3 to 15 fluorine atoms and 1 to 10 C atoms, wherein one or more non-adjacent CH2 groups may be replaced by -O- and / or -S-, Z 1 independently represents a single bond, -CH2CH2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH2O-, -CF2O- or -C≡C-, wherein the asymmetric bridging group may be oriented to both sides, and wherein two O atoms without adjacent groups are directly connected, Sp 1 Represents a single bond or -(CH2) m -, wherein m=1, 2, 3 or 4 and one or both CH2 groups may be replaced by -O- or -S- in such a way that the O / S atoms are not directly connected to each other, Sp 2 represents a straight-chain or branched trivalent spacer group, A 1 represent independently of one another a group selected from the following group: a) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, in which one or more non-adjacent CH2 groups may also be replaced by -O- and / or -S-, and in which one or more H atoms may also be replaced by F or Cl, b) 1,4-phenylene, in which one or two CH groups may also be replaced by N, and in which one or more H atoms may also be replaced by a group L or R 2 Alternative, and c) the group consisting of 2,6-naphthylene, dibenzofuran-3,7-diyl, dibenzothiophene-3,7-diyl, 9H-fluorene-2,7-diyl, phenanthrene-2,7-diyl, 6H-benzo[c]chromene-3,8-diyl, anthracene-2,6-diyl, tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, which may also be mono- or polysubstituted by radicals L, A 2 denotes a 6- or 5-membered saturated, unsaturated or aromatic, carbocyclic or heterocyclic ring system which is optionally additionally substituted in each case by one or two radicals L, L independently represents F, Cl, -CN, an alkyl group having 1 to 5 C atoms, an alkoxy group having 1 to 5 C atoms or an alkenyl group having 2 to 5 C atoms, and n represents 0, 1, 2, 3 or 4.

2. Liquid-crystalline medium according to claim 1, characterized in that The compound of formula I is selected from: Among them, R 1 , R 2 , A 1 , A 2 , Z 1 and n have the meanings as defined in claim 1.

3. Liquid-crystalline medium according to claim 1 or 2, characterized in that The one or more self-aligning additives for vertical alignment comprise one or more non-polymerizable, polymerizable or polymerized compounds of formula II: MES-R a II in MES is a rod-shaped mesogenic group comprising two or more rings directly or indirectly connected to each other or fused to each other, and which is optionally substituted by one or more polymerizable groups connected to MES directly or via a spacer, and R a is a polar anchoring group which is located at the terminal position of the rod-like mesogenic group MES, comprises at least one carbon atom and at least one group selected from -OH, -SH, -COOH, -CHO or a primary or secondary amine function, and which optionally contains one or two polymerizable groups P.

4. A liquid crystal medium according to claim 3, 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 2each independently of one another represents an aromatic, heteroaromatic, alicyclic or heterocyclic radical, which may also contain fused rings and may also be mono- or polysubstituted by radicals L or -Sp-P, L in each case independently of one another representing H, 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, where in addition one or more H atoms may each be 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 represents 0, 1, 2, 3, 4, 5 or 6, 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 represent H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, wherein Furthermore, one or more non-adjacent CH2 groups may 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 furthermore, one or more H atoms may each be replaced by F or Cl, or a -Sp-P group, and R a represents a polar anchor group as defined in claim 3.

5. A liquid crystal medium according to claim 3, wherein the self-aligning additive has an anchor group R selected from the following formulaa 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 independently represent H, alkyl, fluorinated alkyl, OH, NH2, NHR 11 , NR 11 2.OR 11 , C(O)OH, or -CHO, At least one group X 1 represents a compound selected from -OH, -NH2, -NHR 11 , C(O)OH, and -CHO groups, R 11 denotes 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 tri- or tetravalent group.

6. A liquid-crystalline medium according to claim 3, 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 has the meaning defined in claim 4 for formula II, L 1 As defined in L in claim 4, m is 0, 1, 2 or 3, and r1 is 0, 1, 2, 3, or 4.

7. Liquid-crystalline medium according to claim 1 or 2, characterized in that It comprises one or more compounds of formula III in R 21 represents an unsubstituted alkyl group having 1 to 7 C atoms, an unsubstituted alkoxy group having 1 to 6 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, R 22 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkoxy group having 1 to 6 C atoms, express p and q each independently represent 0, 1 or 2, and (p+q) means 1, 2 or 3.

8. Liquid-crystalline medium according to claim 1 or 2, characterized in that It additionally comprises one or more compounds of formula V in R 41 represents an unsubstituted alkyl group having 1 to 7 C atoms or an unsubstituted alkenyl group having 2 to 7 C atoms, and R 42 represents an unsubstituted alkyl group having 1 to 7 C atoms, an unsubstituted alkoxy group having 1 to 6 C atoms, or an unsubstituted alkenyl group having 2 to 7 C atoms.

9. Liquid-crystalline medium according to claim 1 or 2, characterized in that The total concentration of the compound of formula I in the entire medium is 0.005 wt % or more and 0.1 wt % or less.

10. Liquid-crystalline medium according to claim 1 or 2, characterized in that In Formula I R F Indicates the selected formula The group, and n represents 0, 1 or 2.

11. A liquid-crystalline medium according to claim 1 or 2, wherein the one or more compounds of the formula I are selected from the compounds of the formulae IA to IF: The variables here independently have the meanings given in claim 1 or 2.

12. Liquid-crystalline medium according to claim 1 or 2, characterized in that It contains a certain proportion of polymerizable or polymerized compounds.

13. Use of a liquid-crystalline medium according to any one of claims 1 to 12 in electro-optical displays.

14. A method for producing a liquid crystal medium according to any one of claims 1 to 12, characterized in that One or more self-aligning additives for homeotropic alignment and one or more compounds of the formula I are mixed with one or more liquid crystal compounds, and optionally further compounds and additives are added.

15. An electro-optical display comprising a liquid-crystalline medium according to any one of claims 1 to 12.

16. Method for filling an electro-optical display with a liquid-crystalline medium according to any one of claims 1 to 12, characterized in that The medium comprises one or more compounds of formula I and a self-aligning additive for homeotropic alignment.

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