Liquid-crystal medium and liquid-crystal display

Abstract

To provide a liquid-crystal medium with high polarities or high dielectric anisotropy, and suitable properties for practical applications.SOLUTION: The present invention relates to a liquid-crystal medium with positive dielectric anisotropy, comprising one or more stabilizers of formulae S1 and S2, and a stabilizer with a specific phenolic structure.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to liquid-crystalline media and to liquid-crystal displays containing these media, in particular active-matrix addressed displays, in particular twisted nematic ( t wisted n ematic;TN), in-plane switching ( i n- p LANE s switching (IPS) or fringe field switching ( f Ringe- f ield s This applies to FFS (false flip-flag) type displays. [Background technology]

[0002] LCD display ( l iquid- c rystal d LCDs are used in many fields to display information. LCDs are used for both direct-view and projection displays. The electro-optical modes used are, for example, twisted nematic (TN), supertwisted nematic (TNC), and LC-LCD. s Uper t wisted n ematic;STN), optical compensation bend ( o ptically c ompensated b end;OCB), electrically controlled birefringence ( e lectrically c ontrolled birefringence (ECB) mode, and various modifications thereof. All these modes utilize an electric field substantially perpendicular to the substrate or liquid crystal layer. In addition to these modes, there are also electro-optical modes that utilize an electric field substantially parallel to the substrate or liquid crystal layer, such as, for example, the in-plane switching (IPS) mode (disclosed, for example, in DE 4000451 and EP 0588568) and the fringe field switching (FFS) mode, in which there is a strong "fringe field", i.e. a strong electric field close to the edge of the electrode and an electric field with both a strong vertical component and a strong horizontal component throughout the cell. Especially the latter two electro-optical modes are used in LCDs of modern desktop monitors and are intended for use in displays for television and multimedia applications. The liquid crystals according to the invention are preferably used in this type of display. Generally, in FFS displays, dielectrically positive liquid crystal media with rather low values ​​of dielectric anisotropy are used, while in IPS displays, liquid crystal media with a dielectric anisotropy of about 3 or less may also be used.

[0003] These displays require new liquid crystal media with improved properties. In particular, for many types of applications, the address time needs to be improved. Therefore, liquid crystal media with low viscosity (η) and especially low rotational viscosity (γ1) are required. In particular for monitor applications, the rotational viscosity should be below 80 mPa·s, preferably below 60 mPa·s, in particular below 55 mPa·s. In addition to this parameter, the medium must have a nematic phase range of suitable width and position and a suitable birefringence (Δn). Furthermore, the dielectric anisotropy (Δε) should be high enough to allow a fairly low operating voltage. Δε should preferably be greater than 2, more preferably greater than 3, but preferably not greater than 20, in particular not exceeding 17, since this would prevent at least a fairly high resistivity.

[0004] For application as displays in notebooks or other mobile applications, the rotational viscosity should preferably be 120 mPa·s or less, particularly preferably 100 mPa·s or less, while the dielectric anisotropy (Δε) should preferably be greater than 8, particularly preferably greater than 12.

[0005] The display according to the present invention is an active matrix ( a active- m atrix LC D , abbreviated as AMD), preferably thin film transistors ( t hin- f ilm t The liquid crystals according to the invention are preferably addressed by a matrix of thin film transistors (TFTs), however they may also be used to advantage in displays having other known addressing means.

[0006] There are many different display modes that use composite systems of low molecular weight liquid crystal materials and polymer materials. These include, for example, polymer dispersed liquid crystals (PDLCs), as disclosed in WO 91 / 05029. p Olmer d ispersed l iquid c crystal;PDLC), nematic curvilinear alignment phase ( n ematic c urvilinearly a ligned p hase;NCAP) and polymer network ( p Olmer n network;PN) system, or axisymmetric microdomain ( a xiiially s Symmetric m, ASM (Anticrodomain) systems, etc. In contrast to these, a particularly preferred mode according to the invention uses the liquid crystal medium itself aligned on a surface. These surfaces are typically pre-treated to achieve uniform alignment of the liquid crystal material. The display mode according to the invention preferably uses an electric field substantially parallel to the composite layer.

[0007] Liquid crystal compositions suitable for LCDs, and in particular for IPS displays, are known, for example, from JP07-181439(A), EP0667555, EP0673986, DE19509410, DE19528106, DE19528107, WO96 / 23851 and WO96 / 28521. However, these compositions have significant drawbacks. Among other defects, most of them result in disadvantageously long address times, have insufficient resistivity values ​​and / or require excessively high operating voltages. Furthermore, there is a need to improve the low-temperature operation of LCDs. Both improved operating characteristics and improved shelf life, in particular stability to visible light and UV light, as well as to heat, in particular a combination of heat and light and / or UV light, are now required.

[0008] This concerns not only the normal life cycle of the display, but also the individual steps in the manufacture of the display, which may be subject to extreme stresses compared to normal operation. Thus, for example, in the manufacture of the frame bonds, processes are frequently used that cause very high thermal stresses of the display, which already contain liquid crystals. In order for the liquid crystals to withstand this high thermal stress as much as possible without being damaged, it is accordingly advantageous to add one or more heat stabilizers to the liquid crystal formulation. Then, in the subsequent daily operation of the display, the stress due to the light of the backlight and the stress due to the ambient light, typically daylight, and the temperature stress from the environment may arise as important stress factors. This means in particular that the combination of various stress amounts may be particularly important in practice.

[0009] These different combinations of loads can occur either in a sequential or parallel time sequence, so that for example a display used as an electronic advertising panel can be subject to strong heat and solar radiation simultaneously during operation and at rest, depending on its location.

[0010] In particular, EP 3246374 discloses a dielectrically positive LC mixture comprising:

[0011] [ka]

[0012] EP 3112441 also discloses dielectrically positive LC mixtures comprising:

[0013] [ka] [Prior art documents] [Patent documents]

[0014] [Patent Document 1] DE4000451 [Patent Document 2] EP0588568 [Patent Document 3] WO91 / 05029 [Patent Document 4] JP07-181439(A) [Patent Document 5] EP0667555 [Patent Document 6] EP0673986 [Patent Document 7] DE19509410 [Patent Document 8] DE19528106 [Patent Document 9] DE19528107 [Patent Document 10] WO96 / 23851 [Patent Document 11] WO96 / 28521 [Patent Document 12] European Patent No. 3246374 [Patent Document 13] EP3112441 Summary of the Invention [Problem to be solved by the invention]

[0015] Many liquid crystal media, especially those with large polarity or high dielectric anisotropy, do not fulfil the requirements for high stability necessary for practical applications.

[0016] There is therefore a considerable demand for liquid-crystalline media which have suitable properties for practical applications, such as a wide nematic phase range, an appropriate optical anisotropy Δn corresponding to the type of display used, a high Δε and a particularly low viscosity for particularly short response times. [Means for solving the problem]

[0017] Surprisingly, it has now been found that it is possible to achieve liquid-crystalline media which do not have the disadvantages of the materials from the prior art, or at least have them to a significantly reduced extent, and which have a suitably high Δε, an appropriate phase range and an appropriate Δn.

[0018] Surprisingly, it has now been found that compounds of the formulae S1 and S2 shown below bring about a considerable, in most cases sufficient, stabilization of liquid crystal mixtures. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention relates to a liquid-crystalline medium having a nematic phase and positive dielectric anisotropy, which comprises:

[0020] a) one or more compounds of formula S1 and one or more compounds of formula S2, each preferably at a concentration in the range of 1 ppm to 5,000 ppm, more preferably at a concentration in the range of 100 ppm to 2,000 ppm, respectively.

[0021] [ka]

[0022] in which the individual radicals, independently of one another and at each occurrence, have the following meanings, which are identical or different:

[0023] [ka]

[0024] R a-d denotes linear or branched alkyl having 1 to 10 C atoms, preferably having 1 to 6 C atoms, very preferably having 1 to 4 C atoms, most preferably having methyl, X is H, CH3, OH or O · , preferably H, A denotes an optionally substituted linear, branched or cyclic alkylene having 1 to 20 C atoms, preferably -(CH2)8-, and n is an integer of 1 to 6, preferably 3. And,

[0025] b) One or more compounds selected from the group of compounds of formula II and III.

[0026] [ka]

[0027] (In the formula, R 2 and R 3are each independently an alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, an alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, preferably R 2 and R 3 represents alkyl or alkenyl,

[0028] [ka]

[0029] L 21 , L 22 , L 31 and L 32 are each independently H or F, preferably L 21 and / or L 31 indicates F, X 2 and X 3 denote, independently of one another, halogen, a halogenated alkyl or alkoxy having 1 to 3 C atoms or a halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, preferably F, Cl, -OCF3 or -O-CH=CF2, -CF3, in particular F, -OCF3 or -O-CH=CF2, Z 3 denotes -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO- or a single bond, preferably -CH2CH2-, -COO-, trans-CH=CH- or a single bond, very preferably -COO-, trans-CH=CH- or a single bond, and m and n are each independently 0, 1, 2, or 3; m preferably represents 1, 2 or 3, and n is preferably 0, 1 or 2, particularly preferably 1 or 2. and / or

[0030] c) one or more compounds of formula IV. TIFF2024109688000007.tif18158

[0031] (In the formula, R 41 and R 42 are independently of each other R under formula II 2 has the meaning given above for R 41 represents alkyl, R 42 represents alkyl or alkoxy, or R 41 represents alkenyl, R 42 represents an alkyl group,

[0032] [ka]

[0033] Z 41 and Z 42 are independent of each other, and if Z 41 occur twice, they also independently of one another represent -CH2CH2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO-, -CF2O-, -C≡C-, or a single bond, preferably one or more of them represent a single bond, and p represents 0, 1 or 2, preferably 0 or 1. and / or

[0034] d) one or more compounds of formula VIII.

[0035] [ka]

[0036] (In the formula, R 81 and R 82 are independently of each other R under formula II 2 has the meaning given above for

[0037] [ka]

[0038] Z 81 and Z 82 are, independently of one another, -CHCH-, -C≡C-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO-, -CFO- or a single bond, preferably one or more of them denote a single bond and very preferably both denote a single bond, L 81 and L 82 are each independently CF or N, preferably L 81 and L 82 one or both of the following are CF, highly preferably both are CF, and s is 0 or 1, and L 81 and L 82 are each independently CF or N, preferably L 81 and L 82 one or both of the following are CF, highly preferably both are CF; and

[0039] [ka]

[0040] The invention further relates to the LC media described above and below, which further comprise one or more polymerizable compounds.

[0041] In this application, all elements include their respective isotopes.In particular, one or more H in the compound may be replaced by D, which is also particularly preferred in some embodiments.The corresponding high degree of deuteration of the corresponding compound allows, for example, the detection and recognition of the compound.This is very useful in some cases, especially in the case of the compounds of formula S1 and S2.

[0042] In this application, Alkyl is particularly preferably linear alkyl, in particular CH3-, C2H5-, n-C3H7-, n-C4H9- or n-C5H 11 - and Alkenyl particularly preferably denotes CH2=CH-, E-CH3-CH=CH-, CH2=CH-CH2-CH2-, E-CH3-CH=CH-CH2-CH2- or E-(n-C3H7)-CH=CH-.

[0043] The liquid-crystalline medium according to the present application preferably comprises in total 1 ppm to 25,000 ppm, preferably 50 ppm to 20,000 ppm, even more preferably 100 to 15,000 ppm, preferably up to 10,000 ppm and very particularly preferably 200 ppm to 10,000 ppm of compounds of the formulae S1 and S2. In a further preferred embodiment, the liquid-crystalline medium according to the present application comprises in total 1 ppm to 2,000 ppm, preferably 10 ppm to 1,000 ppm, even more preferably 20 to 600 ppm, preferably up to 500 ppm and very particularly preferably 50 ppm to 400 ppm of compounds of the formulae S1 and S2.

[0044] The compounds of the formulae S1 and S2 are eminently suitable as stabilizers of liquid crystal mixtures. In particular, they provide very efficient thermal stabilization of such mixtures. In contrast to these compounds, the compounds hitherto known to provide good thermal stability show more or less significant "voltage holding ratios ( v oltage h olding r This results in a considerable decrease in the viscosity of the mixture (VHR or simply HR for short). In comparison, the compounds of formulae S1 and S2 show a significant improvement. Although the HR of the mixtures after UV exposure often still decreases, this decrease in HR due to UV exposure is significantly reduced compared to what occurs in the case of previously known materials.

[0045] Preferred compounds of formula S1 are selected from the following subformulas:

[0046] [ka]

[0047] Most preferred is the compound of formula S1a.

[0048] Preferred compounds of formula S2 are selected from the following subformulas:

[0049] [ka]

[0050] Most preferred is the compound of formula S2a:

[0051] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds of formulae S1 and S2, preferably selected from the respective preferred sub-formulas, and One or more compounds of formula II, preferably selected from the preferred subformulas thereof, and / or One or more compounds of formula III, preferably selected from the preferred subformulas thereof, and / or One or more compounds of formula IV, preferably selected from the preferred subformulas thereof, and / or One or more compounds of formula VIII, preferably selected from the preferred subformulas thereof Includes.

[0052] In addition to the compounds of the formulae S1 and S2 or preferred sub-formulae thereof, the medium according to the invention preferably comprises one or more dielectrically neutral compounds of the formula Iv in a total concentration in the range from ≧5% to ≦90%, preferably from ≧10% to ≦80%, particularly preferably from ≧20% to ≦70%.

[0053] The compounds of formulae II and III are preferably dielectrically positive compounds, preferably having a dielectric anisotropy of greater than three.

[0054] The compound of formula IV is preferably a dielectrically neutral compound, preferably having a dielectric anisotropy in the range of -1.5 to 3.

[0055] The compounds of formula S1 and S2 are outstandingly suitable as stabilizers for liquid crystal mixtures. In particular, they provide very efficient thermal stabilization of the mixture. Previous materials that provide good thermal stability, more or less, result in a significant decrease in HR when exposed to UV. In comparison, the compounds of formula S1 and S2 show an improvement, i.e., a reduction in the decrease in HR when exposed to UV.

[0056] The individual compounds of formula II and / or III are used in a concentration of 1-20%, preferably 1-15%. These limitations apply in particular when in each case two or more homologous compounds, i.e. compounds of the same formula, are used. When only a single substance of a compound of formula, i.e. only one homolog, is used, its concentration can therefore be in the range of 2-20%, preferably 3-14%.

[0057] In addition to the compounds of the formulae S1 and S2 or their preferred subformulae, the medium according to the invention preferably comprises one or more dielectrically positive compounds having a dielectric anisotropy greater than 3 selected from the group of the formulae II and III.

[0058] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds selected from the group of compounds of the formulae II-1 to II-4, preferably of the formulae II-1 and / or II-2.

[0059] [ka]

[0060] wherein the parameters have the respective meanings given above under Formula II, and L 23 and L 24 are each independently H or F, preferably L 23 indicates F,

[0061] [ka]

[0062] And in the case of formula II-1 and II-4, X 2 preferably denotes F or OCF3, particularly preferably F, and in the case of formula II-3,

[0063] [ka]

[0064] and / or selected from the group of compounds of formulae III-1 and III-2.

[0065] [ka]

[0066] (wherein the parameters have the meanings given under Formula III).

[0067] In a preferred embodiment, the medium according to the invention comprises, instead of or in addition to the compounds of formulae III-1 and / or III-2, one or more compounds of formula III-3.

[0068] [ka]

[0069] (wherein the parameters have the respective meanings given above, and the parameter L 31 and L 32 indicates H or F, independently of each other and other parameters.)

[0070] The medium according to the invention preferably comprises one or more compounds selected from the group of compounds of the formulae II-1 to II-4, in which L 21 and L22 and / or L 23 and L 24 Both indicate F.

[0071] In a preferred embodiment, the medium comprises one or more compounds selected from the group of compounds of formulae II-2 and II-4, where L is 21 , L 22 , L 23 and L 24 All indicate F.

[0072] The medium preferably comprises one or more compounds of formula II-1. The compounds of formula II-1 are preferably selected from the group of the compounds of formulae II-1a to II-1f:

[0073] [ka]

[0074] (wherein the parameters have the respective meanings given above, L 23 ~L 25 indicates H or F, independently of each other and other parameters, and Preferably In formulae II-1a and II-1b, L 21 and L 22 Both indicate F, In formulas II-1c and II-1d, L 21 and L 22 indicates both F and / or L 23 and L 24 both indicate F, In formula II-1e, L 21 , L 22 and L 25 denotes F, and in each case the other parameters have the respective meanings given above.

[0075] Particularly preferred compounds of formula II-1 are the following compounds, especially those of formula II-1a-2:

[0076] [ka]

[0077] (In the formula, R 2 has the meaning given above.)

[0078] The medium preferably comprises one or more compounds of formula II-2, which are preferably selected from the group of compounds of formulae II-2a to II-2k.

[0079] [ka] TIFF2024109688000022.tif193136

[0080] (wherein the parameters have the respective meanings given above, and L 25 ~L 28 are each independently H or F, preferably L 27 and L 28 Both represent H, and particularly preferably L 26 denotes H, and the other parameters have the respective meanings given above.)

[0081] The medium according to the invention preferably comprises one or more compounds selected from the group of compounds of the formulae II-2a to II-2k, in which L 21 and L 22 indicates both F and / or L 23 and L 24 both denote F, and the other parameters have the respective meanings given above.

[0082] In a preferred embodiment, the medium according to the invention comprises one or more compounds selected from the group of compounds of the formulae II-2a to II-2k, in which L 21 , L 22 , L 23 and L 24 all denote F, and the other parameters have the meanings given above.

[0083] Particularly preferred compounds of the formula II-2 are the compounds of the following formulae, particularly preferably the compounds of the formulae II-2a-1 and / or II-2h-1 and / or II-2j-1 and / or II-2k-1:

[0084] [ka] TIFF2024109688000024.tif150140

[0085] (In the formula, R 2 and X 2 has the meaning given above, and X 2 preferably represents F.

[0086] The medium according to the invention preferably comprises one or more compounds of the formula II-3, preferably selected from the group of the compounds of the formulae II-3a to II-3c.

[0087] [ka]

[0088] (wherein the parameters have the respective meanings given above, and L 21 and L 22 Preferably, both represent F.

[0089] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula II-4, preferably of formula II-4a, in which the parameters have the meanings given above, X 2 preferably denotes F or OCF3, particularly preferably F.

[0090] The medium according to the invention preferably comprises one or more compounds of the formula III-1, preferably selected from the group of the compounds of the formulae III-1a to III-1b.

[0091] [ka]

[0092] (wherein the parameters have the respective meanings given above, and the parameter L 33 and L 34 indicates H or F, independently of each other and other parameters.)

[0093] The medium according to the invention preferably comprises one or more compounds of the formula III-1a, preferably selected from the group of the compounds of the formulae III-1a-1 to III-1a-6.

[0094] [ka]

[0095] (In the formula, R 3 has the meaning given above.)

[0096] The medium according to the invention preferably comprises one or more compounds of the formula III-1b, preferably selected from the group of the compounds of the formulae III-1b-1 to III-1b-4, preferably of the formula III-1b-4.

[0097] [ka]

[0098] (In the formula, R 3 has the meaning given above.)

[0099] The medium according to the invention preferably comprises one or more compounds of the formula III-2, preferably selected from the group of the compounds of the formulae III-2a to III-2k.

[0100] [ka] TIFF2024109688000030.tif193138

[0101] where the parameters have the meanings given above, preferably the parameters have the respective meanings given above, and the parameter L 33 , L 34 , L 35 and L 36 indicates H or F, independently of each other and other parameters.)

[0102] The medium according to the invention preferably comprises one or more compounds of the formula III-2a, preferably selected from the group of the compounds of the formulae III-2a-1 to III-2a-5.

[0103] [ka]

[0104] (In the formula, R 3 has the meaning given above.)

[0105] The medium according to the invention preferably comprises one or more compounds of the formula III-2b, preferably selected from the group of compounds of the formulae III-2b-1 to III-2b-2, preferably of the formula III-2b-2.

[0106] [ka]

[0107] (In the formula, R 3 has the meaning given above.)

[0108] The medium according to the invention preferably comprises one or more compounds of the formula III-2c, preferably selected from the group of the compounds of the formulae III-2c-1 to III-2c-6, particularly preferably the compounds of the formulae III-2c-1 and / or III-2c-2 and / or III-2c-4.

[0109] [ka]

[0110] (In the formula, R 3 has the meaning given above.)

[0111] The medium according to the invention preferably comprises one or more compounds selected from the group of the compounds of the formulae III-2d and III-2e, preferably selected from the group of the compounds of the formulae III-2d-1 and III-2e-1.

[0112] [ka]

[0113] (In the formula, R 3 has the meaning given above.)

[0114] The medium according to the invention preferably comprises one or more compounds of the formula III-2f, preferably selected from the group of the compounds of the formulae III-2f-1 to III-2f-5.

[0115] [ka]

[0116] (In the formula, R 3 has the meaning given above.)

[0117] The medium according to the invention preferably comprises one or more compounds of the formula III-2g, preferably selected from the group of the compounds of the formulae III-2g-1 to III-2g-5.

[0118] [ka]

[0119] (In the formula, R 3 has the meaning given above.)

[0120] The medium according to the invention preferably comprises one or more compounds of the formula III-2h, preferably selected from the group of the compounds of the formulae III-2h-1 to III-2h-3, preferably of the formula III-2h-3.

[0121] [ka]

[0122] where the parameters have the meanings given above and X 3 preferably represents F.

[0123] The medium according to the invention preferably comprises one or more compounds of the formula III-2i, which are preferably selected from the group of the compounds of the formulae III-2i-1 to III-2i-2, particularly preferably III-2i-2.

[0124] [ka]

[0125] where the parameters have the meanings given above and X 3 preferably represents F or OCF3.

[0126] The medium according to the invention preferably comprises one or more compounds of the formula III-2j, which are preferably selected from the group of the compounds of the formulae III-2j-1 to III-2j-2, particularly preferably of the formula III-2j-1.

[0127] [ka]

[0128] where the parameters have the meanings given above.

[0129] The medium according to the invention preferably comprises one or more compounds of the formula III-2k, preferably of the formula III-2k-1.

[0130] [ka]

[0131] where the parameters have the meanings given above and X 3 preferably represents F.

[0132] Instead of or in addition to the compounds of formula III-1 and / or III-2, the medium according to the invention may contain one or more compounds of formula III-3.

[0133] [ka]

[0134] (wherein the parameters have the respective meanings given above under Formula III).

[0135] These compounds are preferably selected from the group of formulae III-3a and III-3b.

[0136] [ka]

[0137] (In the formula, R 3 has the meaning given above.)

[0138] The liquid-crystalline media according to the invention preferably comprise a dielectrically neutral component, component C. This component has a dielectric anisotropy in the range from -1.5 to 3. It preferably comprises, more preferably consists mainly of, even more preferably consists essentially of and particularly preferably consists completely of dielectrically neutral compounds having a dielectric anisotropy in the range from -1.5 to 3. This component preferably comprises one or more dielectrically neutral compounds, more preferably consists mainly of, even more preferably consists essentially of and very preferably consists completely of compounds of formula IV having a dielectric anisotropy in the range from -1.5 to 3.

[0139] The dielectrically neutral component, component C, preferably comprises one or more compounds selected from the group of compounds of formulae IV-1 to IV-8.

[0140] [ka]

[0141] (In the formula, R 41 and R 42 has the respective meaning given above under formula IV, and in formulas IV-1, IV-6 and IV-7, R 41 preferably denotes alkyl or alkenyl, preferably alkenyl, R 42 preferably denotes alkyl or alkenyl, preferably alkyl, and in formula IV-2, R 41 and R 42 preferably denotes alkyl, and in formula IV-5, R 41 is preferably alkyl or alkenyl, more preferably alkyl; R 42 is preferably alkyl, alkenyl or alkoxy, more preferably alkenyl or alkoxy, and in formulae IV-4 and IV-8, R 41 preferably denotes alkyl, R 42 preferably represents alkyl or alkoxy, more preferably alkoxy.

[0142] The dielectrically neutral component, component C, preferably comprises one or more compounds selected from the group of compounds of formulae IV-1, IV-5, IV-6 and IV-7, preferably one or more compounds of formulae IV-1 and one or more compounds of formulae IV-5 and IV-6, more preferably one or more compounds of each of formulae IV-1, IV-5 and IV-6, very preferably one or more compounds selected from the group of one or more compounds of formulae IV-1, IV-5, IV-6 and IV-7.

[0143] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula IV-4, more preferably of the formulae CP-Vn and / or CP-nV-m and / or their respective sub-formulae of CP-Vn-m, more preferably of the formulae CP-Vn and / or CP-V2-n, and very preferably of the formulae CP-V-1 and CP-V2-1. The definitions of these abbreviations (acronyms) are given in Table D below or are evident from Tables A to C.

[0144] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula IV-5, more preferably of the respective sub-formulae of formula CCP-Vn and / or CCP-nV-m and / or CCP-Vn-m, more preferably of formula CCP-Vn and / or CCP-V2-n, and very preferably of formula CCP-V-1 and CCP-V2-1. The definitions of these abbreviations (acronyms) are given in Table D below or are evident from Tables A to C.

[0145] In an equally preferred embodiment, the medium according to the invention comprises one or more compounds of formula IV-1, more preferably the respective sub-formulae of formulae CC-nm, CC-nV, CC-n-Vm, CC-VV, CC-V-Vn and / or CC-n-Vm, more preferably the formulae CC-nV and / or CC-n-Vm, and very preferably a compound selected from the group of formulae CC-3-V, CC-4-V, CC-5-V, CC-3-V1, CC-4-V1, CC-5-V1, CC-3-V2 and CC-V-V1. The definitions of these abbreviations (acronyms) are likewise indicated in Table D below or are evident from Tables A-C.

[0146] In a further preferred embodiment of the present invention, which may be the same as or different from the previous ones, the liquid crystal mixture according to the present invention comprises a component C, which preferably consists mainly, and very preferably consists entirely, of compounds of formula IV selected from the group of the compounds of formulae IV-1 to IV-8 and optionally of the compounds of formulae IV-9 to IV-15 above.

[0147] [ka]

[0148] (In the formula, R 41 and R 42 denote, independently of one another, alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, and L 4 indicates H or F.)

[0149] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula IV-10, more preferably selected from the respective subformulae of formulae CPP-3-2, CPP-5-formula 2 and CGP-3-2, more preferably from formulae CPP-3-2 and / or CGP-3-2, and very particularly preferably from formula CPP-3-2. The definitions of these abbreviations (acronyms) are given in Table D below or are evident from Tables A to C.

[0150] The liquid crystal medium according to the invention preferably comprises one or more compounds of the formula V

[0151] [ka]

[0152] (In the formula, R 51 and R 52 are independently of each other R under formula II 2 has the meaning given above for R 51 represents alkyl, R 52 represents alkyl or alkoxy;

[0153] [ka] TIFF2024109688000047.tif163148

[0154] Z 51 and Z 52 are independent of each other, and if Z 51 occur twice, they also independently of one another represent -CH2CH2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO-, -CF2O-, or a single bond, preferably one or more of them represent a single bond, and r represents 0, 1 or 2, preferably 0 or 1, and particularly preferably 1.

[0155] The compound of formula V is preferably a dielectrically neutral compound having a dielectric anisotropy in the range of -1.5 to 3.

[0156] The medium according to the invention preferably comprises one or more compounds selected from the group of compounds of the formulae V-1 and V-2.

[0157] [ka]

[0158] R 51 and R 52 has the respective meaning given above under formula V, R 51 preferably represents alkyl, and in formula V-1, R 52 preferably represents alkenyl, preferably -(CH2)2-CH=CH-CH3, and in formula V-2, R 52 preferably denotes alkyl or alkenyl, preferably -CH=CH2, -(CH2)2-CH=CH2 or -(CH2)2-CH=CH-CH3.

[0159] The medium according to the invention preferably comprises one or more compounds selected from the group of compounds of the formulae V-1 and V-2, in which R 51 preferably denotes n-alkyl, and in formula V-1, R 52 preferably represents alkenyl, and in formula V-2, R 52preferably denotes n-alkyl.

[0160] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula V-1, more preferably of the sub-formula PP-n-2Vm, even more preferably of formula PP-1-2V1, the definitions of which are given in Table D below or are evident from Tables A to C.

[0161] In a preferred embodiment, the medium according to the invention comprises one or more compounds selected from the formula V-2, more preferably the sub-formulae PGP-nm, PGP-nV, PGP-n-2Vm, PGP-n-2V and PGP-n-2Vm, even more preferably the sub-formulae PGP-3-m, PGP-n-2V and PGP-n-V1, very preferably the formulae PGP-3-2, PGP-3-3, PGP-3-4, PGP-3-5, PGP-1-2V, PGP-2-2V and PGP-3-2V. The definitions of these abbreviations (acronyms) are likewise shown in Table D below or are evident from Tables A to C.

[0162] Alternatively or in addition to the compounds of formula II and / or III, the medium according to the invention may contain one or more dielectrically positive compounds of formula VI.

[0163] [ka]

[0164] (In the formula, R 6 represents an alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms, an alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 C atoms, preferably an alkyl or alkenyl,

[0165] [ka]

[0166] L61 and L 62 are each independently H or F, preferably L 61 indicates F, X 6 denotes a halogen, a halogenated alkyl or alkoxy having 1 to 3 C atoms or a halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, preferably F, Cl, -OCF3 or -CF3, very preferably F, Cl or -OCF3, Z 6 denotes -CH2CH2-, -CF2CF2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO- or -CF2O-, preferably -CH2CH2-, -COO-, trans-CH=CH- or a single bond, very preferably -COO- or trans-CH=CH-, and q represents 0 or 1.)

[0167] The medium according to the invention preferably comprises one or more compounds of the formula VI, preferably selected from the group of compounds of the formulae VI-1 and VI-2:

[0168] [ka]

[0169] (wherein the parameters have the respective meanings given above, and the parameter L 63 and L 64 indicates H or F, independently of each other and other parameters, and Z 6 preferably represents -CH2-CH2-.

[0170] The compounds of formula VI-1 are preferably selected from the group of compounds of formulae VI-1a and VI-1b.

[0171] [ka]

[0172] (In the formula, R6 has the meaning given above.)

[0173] The compound of the formula VI-2 is preferably selected from the group of the compounds of the formulae VI-2a to VI-2d.

[0174] [ka]

[0175] (In the formula, R 6 has the meaning given above.)

[0176] Furthermore, the liquid crystal medium according to the invention may comprise one or more compounds of the formula VII.

[0177] [ka]

[0178] (In the formula, R 7 is represented by the formula II under R 2 has the meaning given above for

[0179] [ka] TIFF2024109688000056.tif109123

[0180] Z 71 and Z 72 represent, independently of one another, -CH2CH2-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO-, -CF2O- or a single bond, preferably one or more of them represent a single bond, very preferably both represent a single bond, t represents 0, 1 or 2, preferably 0 or 1, more preferably 1; and X 7 is represented by the formula II under X 2 or R 7Independently of R 7 (It may have one of the meanings given for

[0181] The compound of formula VII is preferably a dielectrically positive compound.

[0182] Furthermore, the liquid crystal medium according to the invention may comprise one or more compounds of the formula VIII.

[0183] [ka]

[0184] (In the formula, R 81 and R 82 are independently of each other R under formula II 2 has the meaning given above for

[0185] [ka]

[0186] Z 81 and Z 82 are, independently of one another, -CHCH-, -C≡C-, -COO-, trans-CH=CH-, trans-CF=CF-, -CHO-, -CFO- or a single bond, preferably one or more of them denote a single bond and very preferably both denote a single bond, s is 0 or 1, and L 81 and L 82 are each independently CF or N, preferably L 81 and L 82 one or both of the following are CF, highly preferably both are CF; and

[0187] [ka]

[0188] L 81 and L 82 Alternatively, one or both of the may represent CH.)

[0189] The compound of formula VIII is preferably a dielectrically negative compound. Preferably, the compound of formula VIII is selected from the following group of compounds of sub-formula VIII:

[0190] [ka]

[0191] in which the individual radicals, independently of one another and at each occurrence, have the following meanings, which are identical or different:

[0192] [ka]

[0193] At least one ring F is cyclohexenylene; R 1 and R 2 is alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH groups may be further replaced by -O-, -CH=CH-, -CO-, -OCO-, or -COO- in a form in which the O atoms are not directly bonded to each other, and is preferably alkyl or alkoxy having 1 to 6 C atoms; Z X and Z y is -CH2CH2-, -CH=CH-, -CF2O-, -OCF2-, -CH2O-, -OCH2-, -CO-O-, -O-CO-, -C2F4-, -CF=CF-, -CH=CH-CHO- or a single bond, preferably a single bond; L 1-4 are F, Cl, OCF3, CF3, CH3, CH2F, and CHF2, a is 1 or 2; b is 0 or 1, and f is 1 or 2.

[0194] The liquid crystal media according to the invention preferably comprise one or more compounds selected from the group of the compounds of the formulae I to VIII, preferably I to VII, more preferably I and II and / or III and / or IV and / or VI. They particularly preferably consist mainly of, even more preferably consist essentially of and very preferably consist entirely of, these compounds.

[0195] In this application, "comprise" in relation to a composition means that the entity, i.e., medium or component, in question contains the indicated component or components or compounds, preferably at a total concentration of 10% or more, highly preferably 20% or more.

[0196] In this context, "predominantly consist of" means that the entity in question contains 55% or more, preferably 60% or more, and very preferably 70% or more of the indicated component or components or compounds.

[0197] In this context, "essentially consist of" means that the entity in question contains 80% or more, preferably 90% or more, and very preferably 95% or more of the indicated component or components or compounds.

[0198] In this context, "virtually completely consist of" or "entirely consist of" means that the entity in question contains 98% or more, preferably 99% or more, and very preferably 100% of the indicated component or components or compounds.

[0199] Other mesogenic compounds not explicitly mentioned above may optionally be used advantageously in the media according to the invention. Such compounds are known to those skilled in the art.

[0200] The liquid-crystalline media according to the invention preferably have a clearing point of 70° C. or more, more preferably 75° C. or more, particularly preferably 80° C. or more and very particularly preferably 85° C. or more.

[0201] The nematic phase of the medium according to the present invention preferably ranges from at least 0°C or less to 70°C or more, more preferably from at least -20°C or less to 75°C or more, very preferably from at least -30°C or less to 75°C or more, in particular from at least -40°C or less to 80°C or more.

[0202] The Δε of the liquid-crystalline media according to the invention at 1 kHz and 20° C. is preferably greater than or equal to 2, more preferably greater than or equal to 3, even more preferably greater than or equal to 4 and very preferably greater than or equal to 6. Δε is preferably less than or equal to 30, and Δε is particularly preferably less than or equal to 20.

[0203] The Δn of the liquid-crystalline media according to the invention is D ) and at 20° C., preferably in the range from ≧0.060 to ≦0.300, preferably in the range from ≧0.070 to ≦0.150, more preferably in the range from ≧0.080 to ≦0.140, even more preferably in the range from ≧0.090 to ≦0.135, and very particularly preferably in the range from ≧0.100 to ≦0.130.

[0204] In a first preferred embodiment of the present application, Δn of the liquid-crystalline medium according to the present invention is preferably in the range from ≥ 0.080 to ≤ 0.120, more preferably from ≥ 0.090 to ≤ 0.110 and very particularly preferably in the range from ≥ 0.095 to ≤ 0.105, whereas Δε is preferably in the range from ≥ 6 to ≤ 11, preferably in the range from ≥ 7 to ≤ 10 and particularly preferably in the range from ≥ 8 to ≤ 9.

[0205] In this embodiment, the nematic phase of the medium according to the invention ranges from at least -20°C or less to 70°C or more, more preferably from at least -20°C or less to 70°C or more, very preferably from at least -30°C or less to 70°C or more, in particular from at least -40°C or less to 70°C or more.

[0206] In a second preferred embodiment of the present application, Δn of the liquid-crystalline medium according to the invention is preferably in the range from 0.060 to 0.300, preferably in the range from 0.100 to 0.140, more preferably in the range from 0.110 to 0.130 and very particularly preferably in the range from 0.115 to 0.125, while Δε is preferably in the range from 7 to 13, preferably in the range from 9 to 20 and particularly preferably in the range from 10 to 17.

[0207] In this embodiment, the nematic phase of the medium according to the invention preferably ranges from at least -20°C or less to 80°C or more, more preferably from at least -20°C or less to 85°C or more, very preferably from at least -30°C or less to 80°C or more, in particular from at least -40°C or less to 85°C or more.

[0208] According to the invention, the compounds of formulae S1 and S2 together are preferably used in the medium in a total concentration of the entire mixture of 1 ppm to 5,000%, more preferably 10 ppm to 3,000 ppm, more preferably 100 ppm to 2,000 ppm, more preferably 200 ppm to 1500 ppm, very preferably 250 ppm to 1000 ppm.

[0209] The compounds selected from the group of formulae II and III are preferably used in a total concentration of 2% to 60%, more preferably 3% to 35%, even more preferably 4% to 20%, very preferably 5% to 15% of the total mixture.

[0210] The compound of formula IV is preferably used in a total concentration of from 5% to 70%, more preferably from 20% to 65%, even more preferably from 30% to 60%, very preferably from 40% to 55% of the total mixture.

[0211] The compound of formula V is preferably used in a total concentration of 0% to 30%, more preferably 0% to 15%, very preferably 1% to 10% of the total mixture.

[0212] The compound of formula VI is preferably used in a total concentration of 0% to 50%, more preferably 1% to 40%, even more preferably 5% to 30%, very preferably 10% to 20% of the total mixture.

[0213] The medium according to the invention may optionally contain further liquid crystal compounds to adjust the physical properties. Such compounds are known to those skilled in the art. Their concentration in the medium according to the invention is preferably 0% to 30%, more preferably 0.1% to 20%, very preferably 1% to 15%.

[0214] In a preferred embodiment, the concentration of the compound of formula CC-3-V in the medium according to the invention may be between 50% and 65%, particularly preferably between 55% and 60%.

[0215] The liquid-crystalline media preferably comprise in total 50 to 100%, more preferably 70 to 100%, very preferably 80 to 100%, in particular 90 to 100% of compounds of the formulae I to VII, preferably selected from the group of compounds of the formulae I-1, I-2 and II to VI, particularly preferably I to V, in particular the group of compounds of the formulae I-1, I-2, II, III, IV, V and VII, and very particularly preferably the group of compounds of the formulae I-1, I-2, II, III, IV and V. They preferably consist predominantly of these compounds, very preferably essentially completely of these compounds. In a preferred embodiment, the liquid-crystalline medium in each case comprises one or more compounds of each of these formulae.

[0216] In the present application, the expression dielectrically positive denotes compounds or components with Δε>3.0, dielectrically neutral denotes those with -1.5≦Δε≦3.0, and dielectrically negative denotes those with Δε<-1.5. Δε is measured at a frequency of 1 kHz and at 20°C. The dielectric anisotropy of each compound is determined from the results of a 10% solution of each individual compound in a nematic host mixture. If the solubility of the respective compound in the host mixture is less than 10%, the concentration is reduced to 5%. The capacitance of the test mixtures is determined both in cells with homeotropic alignment and in cells with homogeneous alignment. The cell thickness of both types of cells is about 20 μm. The voltage applied is a square wave with a frequency of 1 kHz and an effective value usually between 0.5 V and 1.0 V, but always chosen to be lower than the capacitance threshold of the respective test mixture.

[0217] Δε is (ε || -ε ⊥ ), while ε av. is (ε || +2ε ⊥ ) / 3.

[0218] The host mixture used for the dielectrically positive compounds is mixture ZLI-4792, and for the dielectrically neutral and dielectrically negative compounds is mixture ZLI-3086 (both from Merck KGaA, Germany). The absolute values ​​of the dielectric constants of the compounds are determined from the change in the respective values ​​of the host mixtures upon addition of the compound of interest. The values ​​are extrapolated to a concentration of the compound of interest of 100%.

[0219] Components that have a nematic phase at the measurement temperature of 20° C. are measured as is, all others are treated as compounds.

[0220] In this application, unless otherwise specified in either case, the expression threshold voltage refers to the optical threshold, which is the threshold voltage at which a relative contrast of 10% (V 10 ), and the expression saturation voltage refers to optical saturation, the voltage at which 90% relative contrast (V 90 ) is given by the Freedericks threshold (V FrThe capacitive threshold voltage (V0), also called the capacitive threshold voltage (V), is used only when explicitly mentioned.

[0221] All parameter ranges given in this application are inclusive of the limits unless otherwise stated.

[0222] The different upper and lower limits given for the various range properties may be combined with each other to create additional preferred ranges.

[0223] Throughout this application, the following conditions and definitions apply unless otherwise stated: All concentrations are given in weight percent and relate to the respective mixture as a whole, all temperatures are given in degrees Celsius, and all temperature differences are given in degrees Celsius. All physical properties are determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status Nov. 1997, Merck KGaA, Germany, and are given for a temperature of 20° C., unless otherwise stated. The optical anisotropy (Δn) is measured at a wavelength of 589.3 nm. The dielectric anisotropy (Δε) is determined at a frequency of 1 kHz. The threshold voltages, as well as all other electro-optical properties, are determined using test cells manufactured by Merck KGaA, Germany. The test cells for the measurement of Δε have a cell thickness of about 20 μm. The electrodes are 1.13 cm 2 The ITO electrodes are circular with an area of ​​10 μm and a guard ring. The alignment layer is Nissan Chemical's SE-1211 (ε || ), and polyimide AL-1054 (ε ⊥ ) The capacitance is 0.3V rms The characteristic voltages are determined using a Solatron 1260 frequency response analyzer using a sine wave of a voltage of 1000 V. The light used in the electro-optical measurements is white light. Here, a setup using a commercially available DMS instrument from Autronic-Melchers (Germany) is used. The characteristic voltages are determined with perpendicular observation. The threshold voltage (V 10 ), Mid Gray (V 50 ) and saturation (V90 ) voltages were determined at 10%, 50%, and 90% relative contrast, respectively.

[0224] The liquid-crystalline media according to the invention may contain further additives and chiral dopants in the usual concentrations. The total concentration of these further components ranges from 0% to 10%, preferably from 0.1% to 6%, based on the entire mixture. The concentrations of the individual compounds used are preferably in the range of 0.1% to 3%, respectively. In the present application, when values ​​and concentration ranges of the liquid-crystalline components and compounds of the liquid-crystalline media are given, the concentrations of these and similar additives are not taken into account.

[0225] The liquid crystal media according to the invention consist of a number of compounds, preferably 3 to 30, more preferably 4 to 20, very preferably 4 to 16. These compounds are mixed in a conventional manner. In general, the desired amount of the compound used in a smaller amount is dissolved in the compound used in a larger amount. It is particularly easy to observe the completion of the dissolution process if the temperature is above the clearing point of the compound used in a higher concentration. However, it is also possible to prepare the media in other conventional ways, for example using so-called premixes, which may be homologous or eutectic mixtures of compounds, or using the so-called "multi-bottle" system, in which the components are themselves ready-to-use mixtures.

[0226] By adding suitable additives the liquid crystal media according to the invention can be adapted for use in all known types of liquid crystal displays, either using the liquid crystal medium itself, like TN, TN-AMD, ECB-AMD, VAN-AMD, IPS-AMD, FFS-AMD LCDs, or composite systems like PDLC, NCAP, PN LCDs, in particular ASM-PA LCDs.

[0227] All temperatures, e.g. the melting point T(C,N) or T(C,S) of a liquid crystal, the transition from the smectic (S) to the nematic (N) phase T(S,N) and the clearing point T(N,I), are given in degrees Celsius. All temperature differences are given in differential degrees.

[0228] In the present invention and in particular in the following examples, the structures of the mesogenic compounds are indicated by abbreviations, also called acronyms, in which the chemical formulae are abbreviated as follows, using the following tables A to 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 denotes linear alkyl or alkenyl, preferably 1E-alkenyl, with n, m and l C atoms, respectively. Table A lists the codes used for the ring elements of the core structure of the compounds, while Table B shows the linking groups. Table C shows the meaning of the codes for the left-hand or right-hand side groups. The acronyms consist of the code for the ring element with the optional linking group, followed by a first hyphen and the code for the left-hand terminal group, and a second hyphen and the code for the right-hand terminal group. Table D shows the respective abbreviations together with examples of the structures of the compounds.

[0229] [Table 1] TIFF2024109688000063.tif141152

[0230] [Table 2]

[0231] [Table 3]

[0232] Here, n and m each represent an integer, and the three dots "..." are placeholders for other abbreviations from this table.

[0233] The following table shows exemplary structures and their respective abbreviations, which are presented to illustrate the meaning of the abbreviation rules, which further represent the compounds that are preferably used:

[0234] [Table 4] TIFF2024109688000067.tif25194TIFF2024109688000068.tif25397TIFF20241096880 00069.tif252106TIFF2024109688000070.tif252103TIFF2024109688000071.tif25310 4TIFF2024109688000072.tif252111TIFF2024109688000073.tif25274TIFF2024109688 000074.tif25369TIFF2024109688000075.tif25289TIFF2024109688000076.tif25388T IFF2024109688000077.tif25395TIFF2024109688000078.tif25396TIFF2024109688000 079.tif253101TIFF2024109688000080.tif253113TIFF2024109688000081.tif253113T IFF2024109688000082.tif253113TIFF2024109688000083.tif253107TIFF20241096880 00084.tif253113TIFF2024109688000085.tif25388TIFF2024109688000086.tif127115

[0235] Here, n, m and l preferably each independently represent 1 to 7.

[0236] The following table, Table E, shows exemplary compounds which may be used as additional stabilizers in the mesogenic medium according to the present invention.

[0237] [Table 5] TIFF2024109688000088.tif247141

[0238] In a preferred embodiment of the invention the mesogenic medium comprises one or more compounds selected from the group of compounds from Table E.

[0239] Table F below shows exemplary compounds which may preferably be used as chiral dopants in the mesogenic media according to the present invention.

[0240] [Table 6] TIFF2024109688000090.tif254118

[0241] In a preferred embodiment of the invention the mesogenic medium comprises one or more compounds selected from the group of compounds from Table F.

[0242] A mesogenic medium according to the present application preferably comprises two or more, preferably four or more compounds selected from the group consisting of the compounds in the table above.

[0243] The liquid crystal media according to the invention preferably comprise 7 or more, preferably 8 or more individual compounds, preferably 3 or more, particularly preferably 4 or more different formulae selected from the group of compounds of table D. EXAMPLES

[0244] The following examples illustrate the invention without in any way limiting it.

[0245] However, the physical properties indicate to the skilled artisan what properties are achievable and to what extent they can be modified, so that the various property combinations which are particularly preferred and achievable are well defined for the skilled artisan.

[0246] Liquid crystal mixtures having the compositions and properties shown in the table below have been prepared and investigated.

[0247] Example 1 An LC mixture with positive dielectric anisotropy (M-1.0) is prepared as follows.

[0248] [Table 7]

[0249] The above mixture (M1-0) is divided into four portions. The first portion is investigated as is. To each of three further portions, either 300 ppm, 500 ppm or 1,000 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added (mixtures M-11 through M-1-3).

[0250] [ka]

[0251] Usage example LC media M1-1 to M-1-3 formulated as in Example 1 are filled into the VHR test cell as described above.

[0252] The test cell is subjected to thermal stress (100°C). The VHR is measured for various time intervals (t heat ) and then measured as described above. For comparison purposes, the measurement is repeated using a reference LC medium M1-0, prepared as in Example 1. The VHR values ​​are shown in Table 1 below.

[0253] [Table 8]

[0254] Another set of test cells is exposed to the backlight unit of the LCD. The VHR is then changed for various time intervals (t light ) and then measured as above. The VHR values ​​are shown in Table 2 below.

[0255] [Table 9]

[0256] It can be seen that LC media M1-1 to M-1-3 containing both stabilizers S1a and S2a1 show a significantly smaller decrease in VHR after prolonged heat exposure compared to LC medium M-1 which does not contain the compounds of formulae S1 and S2.

[0257] The absence of the additive results in a significant decrease in the HR of the mixture after heating and after backlight testing.

[0258] Example 2 An LC mixture with positive dielectric anisotropy (M-2.0) is prepared as follows.

[0259] [Table 10]

[0260] To the above mixture, 1,000 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added. The resulting mixture shows excellent stability against both thermal and backlight loads.

[0261] Example 3 An LC mixture with positive dielectric anisotropy (M-3.0) is prepared as follows.

[0262] [Table 11]

[0263] To the above mixture, 500 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added. The resulting mixture shows excellent stability against both thermal and backlight loads.

[0264] Example 4 An LC mixture with positive dielectric anisotropy (M-4.0) is prepared as follows.

[0265] [Table 12]

[0266] To each of the portions of each of the above mixtures, 500 ppm of stabilizer S2a1 is added, and either 100 ppm, 500 ppm, 1000 ppm or 1500 ppm of stabilizer S1a is added. The resulting mixtures show excellent stability against both thermal and backlight loads.

[0267] Example 5 An LC mixture with positive dielectric anisotropy (M-5.0) is prepared as follows.

[0268] [Table 13]

[0269] To the above mixture, 300 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added. The resulting mixture shows excellent stability against both thermal and backlight loads.

[0270] Example 6 An LC mixture with positive dielectric anisotropy (M-6.0) is prepared as follows.

[0271] [Table 14]

[0272] To the above mixture, 300 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added. The resulting mixture shows excellent stability against both thermal and backlight loads.

[0273] Example 7 An LC mixture with positive dielectric anisotropy (M-7.0) is prepared as follows.

[0274] [Table 15]

[0275] To each part of the above mixture, 300 ppm of stabilizer S1a and 200 ppm, 500 ppm or 800 ppm of stabilizer S2a1 are added respectively. The resulting mixtures show excellent stability against both thermal and backlight loads.

[0276] Example 8 An LC mixture with positive dielectric anisotropy (M-8.0) is prepared as follows.

[0277] [Table 16]

[0278] To each part of the above mixture, 600 ppm of stabilizer S2a1 and 300 ppm or 500 ppm of stabilizer S1a are added respectively. The resulting mixtures show excellent stability against both thermal and backlight loads.

[0279] Example 9 An LC mixture with positive dielectric anisotropy (M-9.0) is prepared as follows.

[0280] [Table 17]

[0281] To the above mixture, 500 ppm of stabilizer S1a and 500 ppm of stabilizer S2a1 are added. The resulting mixture shows excellent stability against both thermal and backlight loads.

Claims

1. A liquid crystal medium having positive dielectric anisotropy, characterized by including the following: a) One or more compounds of formulas S1 and S2 【Chemistry 1】 (In the formula, each base is independent of the others and, in each instance, identical or different, and has the following meanings: 【Chemistry 2】 R ａ ~R ｄ This represents a linear or branched alkyl group having 1 to 10 carbon atoms. X is H, CH ３ , indicates OH or O●, A represents a linear, branched, or cyclic alkylene having 1 to 20 C atoms which may be substituted, and n represents an integer between 1 and 6. Furthermore, b) One or more compounds selected from the group of compounds of formulas II and III. 【Transformation 3】 (In the formula, R ２ and R ３ These independently represent alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms, and alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 carbon atoms. 【Chemistry 4】 L ２１ 、L ２２ 、L ３１ and L ３２ each independently represents H or F, X ２ and X ３ These independently represent a halogen, an alkyl or alkoxy halide having 1 to 3 carbon atoms, or an alkenyl or alkenyloxy halide having 2 or 3 carbon atoms. Z ３ is, -CH ２ CH ２ -, -CF ２ CF ２ -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ It shows an O- or single bond, and m and n independently represent 0, 1, 2, or 3. Furthermore / or, c) One or more compounds of formula IV 【Transformation 5】 (In the formula, R ４１ and R ４２ These are independent of each other, and R is under Equation II. ２ The above has the meanings, 【Transformation 6】 Z ４１ and Z ４２ They are independent of each other, and if Z ４１ If it appears twice, these also appear independently of each other, -CH ２ CH ２ -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ O-, -CF ２ It shows O-, -C≡C-, or a single bond, and p represents 0, 1, or 2. Furthermore / or, d) One or more compounds of formula VIII 【Transformation 7】 (In the formula, R ８１ and R ８２ R is independent of each other. ２ It has meaning in relation to, and 【Transformation 8】 【Chemistry 9】 Z ８１ and Z ８２ They are independent of each other, -CH ２ CH ２ -, -C≡C-, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ O-, -CF ２ It shows O- or a single bond, s represents 0 or 1, and L ８１ and L ８２ These independently represent C-F or N, and 【Chemistry 10】 L ８１ and L ８２ One or both of these may alternatively represent C-H. However, the liquid crystal medium is a compound of formula IV, consisting of one or more compounds with the acronym CC-n-V, one or more compounds with the acronym CC-n-Vm, and one or more compounds with the acronym CC-n-mVl. 【Chemistry 11】 (In the formula, n, m, and l each independently represent numbers from 1 to 7. Includes.

2. The medium according to Claim 1, characterized in that the compound of the acronym CC-n-Vm is selected from the acronym CC-n-V1, and the compound of the acronym CC-n-mVl is selected from the acronym CC-n-2V1.

3. The medium according to claim 1 or 2, characterized in that in the acronyms CC-n-V, CC-n-Vm, and CC-n-mVl, n represents 3.

4. The medium according to any one of claims 1 to 3, characterized in that the total concentration of the compounds of the acronyms CC-n-V, CC-n-Vm, and CC-n-mVl is 40 to 55% by weight.

5. The medium according to any one of claims 1 to 4, characterized in that the compound of formula VIII includes one or more compounds selected from the group consisting of compounds of formula CY, PY, and LY. 【Chemistry 12】 (In the formula, each base is independent of the others and, in each instance, is the same or different, and has the following meanings: 【Chemistry 13】 However, at least one of the ring F is cyclohexenylene, R1 and R2 are alkyl groups having 1 to 12 carbon atoms, and here, one or two non-adjacent CH2 groups may further be substituted with -O-, -CH=CH-, -CO-, -OCO-, or -COO- in a manner in which the oxygen atoms are not directly bonded to each other. Z X and Z y are -CH 2 CH 2 -, -CH=CH -, -CF 2 O -, -OCF 2 -, -CH 2 O -, -OCH 2 -, -CO-O -, -O-CO -, -C 2 F 4 -, -CF=CF -, -CH=CH-CH 2 O - or single bonds. L1-4 are F, Cl, OCF3, CF3, CH3, CH2F, CHF2, a is either 1 or 2, b is 0 or 1, and f is either 1 or 2.

6. The medium according to any one of claims 1 to 5, characterized in that in formula S1, X represents H.

7. The medium according to any one of claims 1 to 6, characterized in that the compound of formula S1 is selected from formula S1a or S1b. 【Chemistry 14】

8. The medium according to any one of claims 1 to 7, characterized in that the compound of formula S2 is selected from formula S2a or S2b. 【Chemistry 15】 (In the formula, n represents an integer between 1 and 6.

9. The medium according to any one of claims 1 to 8, characterized in that it contains one or more compounds of formula II-2 as the compound of formula II. 【Chemistry 16】 (In the formula, the parameters have the respective meanings shown in formula II, and L 23 and L 24 independently represent H or F.)

10. The medium according to claim 9, characterized in that the compound of formula II-2 contains one or more compounds selected from the group consisting of compounds with the acronyms APUQU-n-F, PGUQU-n-F, or DGUQU-n-F. 【Chemistry 17】 (In the formula, n represents an integer between 1 and 7.

11. The medium according to claim 10, characterized in that the compound of formula II-2 comprises one or more compounds of the acronym APUQU-n-F, one or more compounds of the acronym PGUQU-n-F, and one or more compounds of the acronym DGUQU-n-F.

12. The medium according to any one of claims 1 to 11, characterized by including the following: - One or more compounds selected from the compound groups of formulas II and III (excluding the compound of formula II-2). [Chemistry 18] (In the formula, R ２ and R ３ These independently represent alkyl, alkoxy, fluorinated alkyl or fluorinated alkoxy having 1 to 7 carbon atoms, and alkenyl, alkenyloxy, alkoxyalkyl or fluorinated alkenyl having 2 to 7 carbon atoms. 【Chemistry 19】 L ２１ , L ２２ , L ３１ and L ３２ These independently represent either H or F. X ２ and X ３ These independently represent a halogen, an alkyl or alkoxy halide having 1 to 3 carbon atoms, or an alkenyl or alkenyloxy halide having 2 or 3 carbon atoms. Z ３ is, -CH ２ CH ２ -, -CF ２ CF ２ -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ It shows an O- or single bond, and m and n independently represent 0, 1, 2, or 3.

13. The medium according to any one of claims 1 to 12, characterized by including the following: - One or more compounds of formula IV (excluding compounds with the acronyms CC-n-V, CC-n-Vm, or CC-n-mVl). 【Chemistry 20】 (In the formula, R ４１ and R ４２ These are independent of each other, and under equation II, R ２ The above has the meanings, 【Chemistry 21】 Z ４１ and Z ４２ They are independent of each other, and if Z ４１ If it appears twice, these also appear independently of each other, -CH ２ CH ２ -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ O-, -CF ２ It shows O-, -C≡C-, or a single bond, and p represents 0, 1, or 2.

14. The medium according to any one of claims 1 to 13, characterized in that the total concentration of the compounds of formulas S1 and S2 in the medium is in the range of 1 ppm to 5,000 ppm.

15. The medium according to any one of claims 1 to 14, characterized by containing one or more dielectrically neutral compounds of formula V. 【Chemistry 22】 (In the formula, R ５１ and R ５２ These are independent of each other, and under equation II, R ２ It has the meaning shown in relation to, 【Chemistry 23】 Z ５１ and Z ５２ They are independent of each other, and if Z ５１ If it appears twice, these also appear independently of each other, -CH ２ CH ２ -, -COO-, trans-CH=CH-, trans-CF=CF-, -CH ２ O-, -CF ２ O-, or a single bond, and r represents 0, 1, or 2.

16. A liquid crystal display characterized by including the medium described in any one of claims 1 to 15.

17. The display according to claim 16, characterized in that it is addressed by an active matrix.

18. Use of the medium described in any one of claims 1 to 15 in a liquid crystal display.

19. A method for preparing a medium according to any one of claims 1 to 15, characterized in that one or more compounds of formulas S1 and S2 described in claim 1 are mixed with one or more compounds of the acronym CC-n-V, one or more compounds of the acronym CC-n-Vm, and one or more compounds of the acronym CC-n-mVl, and / or one or more further mesogenic compounds, and / or one or more additives.

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