Liquid-crystalline medium, method for stabilizing same and liquid-crystalline display

Abstract

The present invention relates to a liquid-crystalline medium, to a method for stabilizing it and to a liquid-crystalline display. The invention relates to compounds of formula I and to a liquid-crystalline medium, preferably having a nematic phase and a negative dielectric anisotropy, comprising a) one or more compounds of formula I and b) one or more compounds of formula III-O wherein the parameters have the respective meanings indicated in claim 1; to the use thereof in electro-optical displays, in particular in active matrix displays based on the VA, ECB, PALC, FFS or IPS effect; to such displays comprising such a liquid-crystalline medium; and to the use of compounds of formula I for stabilizing a liquid-crystalline medium comprising one or more compounds of formula III-O.

Description

[0001] This application is a divisional application of Chinese patent application No. 201310756713.6, filed on October 18, 2013, entitled "Liquid Crystal Medium, Method for Stabilizing the Same and Liquid Crystal Display". Technical Field

[0002] This invention relates to novel compounds, particularly for use in liquid crystal media, and also to the use of such liquid crystal media in liquid crystal displays; and to such liquid crystal displays, particularly those utilizing the ECB (electro-controlled birefringence) effect of dielectric negative liquid crystals with perpendicular initial alignment. The liquid crystal media according to the invention are characterized by a particularly short response time and a high voltage retention rate (VHR, or may be abbreviated as HR) in displays according to the invention. Background Technology

[0003] The principle of electrically controlled birefringence, the ECB effect or DAP (distortion of phases) effect, was first described in 1971 (M. F. Chieckel and K. Fahrenschon, “Deformation of nematic liquid crystals with vertical orientation in electrical fields”, Appl. Phys. Lett. 19 (1971), 3912). This was followed by papers by J. F. Kahn (Appl. Phys. Lett. 20 (1972), 1193) and G. Labruinie and J. Robert (J. Appl. Phys. Lett. 44 (1973), 4869).

[0004] Papers by J. Robert and F. Clerc (SID 80 Digest Techn. Papers (1980), 30), J. Duchene (Displays 7 (1986), 3), and H. Schad (SID 82 Digest Techn. Papers (1982), 244) have shown that, for high-information display elements based on the ECB effect, the liquid crystal phase must have a high elastic constant ratio K3 / K1, a high optical anisotropy value Δn, and a dielectric anisotropy value ≤-0.5 Δε. Electro-optic display elements based on the ECB effect have vertical edge alignment (VA technology = vertical alignment). Dielectric-negative liquid crystal media can also be used in displays utilizing the so-called IPS (in-plane switching) effect.

[0005] This effect necessitates LC phases that meet a variety of requirements for industrial applications in electro-optic display elements. Of particular importance are resistance to moisture, air, and physical influences such as heat, radiation in the infrared, visible, and ultraviolet regions, as well as chemical resistance to DC and AC electric fields.

[0006] In addition, LC phases that can be used industrially need to have a liquid crystal mesocrystalline phase and low viscosity within a suitable temperature range.

[0007] None of the compounds disclosed to date that possess a liquid crystal mesocrystalline phase include a single compound that satisfies all these requirements. Therefore, mixtures of 2 to 25, preferably 3 to 18, compounds are typically prepared to obtain substances that can be used as LC phases.

[0008] Matrix liquid crystal displays (MLC displays) are known. Nonlinear elements, such as active elements (i.e., transistors), can be used to switch individual pixels individually. Thus, the term "active matrix" is used, which is typically made using thin-film transistors (TFTs) generally disposed on a glass plate serving as a substrate.

[0009] There is a distinction between the two technologies: TFTs that incorporate compound semiconductors (such as CdSe) or TFTs based on polycrystalline and, especially, amorphous silicon. The latter technology currently holds the greatest commercial importance worldwide.

[0010] A TFT matrix is ​​applied to the inside of one glass plate of the display, while another glass plate has a transparent counter electrode on its inside. Compared to the size of the pixel electrode, the TFT is very small and has virtually no negative impact on the image. This technology can also be extended to image displays with full-color capabilities, where mosaics of red, green, and blue filters are arranged such that the filter elements are opposite each switchable pixel.

[0011] To date, the most commonly used TFT displays typically operate with orthogonal polarizers in transmission mode and are backlit. For TV applications, IPS or ECB (or VAN) cells are used; however, monitors typically use IPS or TN (twisted nematic) cells, and laptops, mobile devices, and other applications often use TN cells.

[0012] Here, the term MLC display includes any matrix display with integrated nonlinear elements, that is, in addition to active matrices, it also includes displays with passive elements such as variable resistors or diodes (MIM = metal-insulator-metal).

[0013] This type of MLC display is particularly suitable for TV applications, monitors, and laptops, or for displays with high information density, such as those used in automobile manufacturing or aircraft construction. Besides issues concerning the angle dependence of contrast and response time, MLC displays also face many challenges due to the insufficient specific resistivity of the liquid crystal mixture [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E., SORIMACHI, K., TAJIMA, E., WATA-NABE, H., SHIMIZU, H., Proc. Eurodisplay 84, Sept. 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 ff., Paris; STROMER, M., Proc. Eurodisplay 84, Sept. 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145 ff., Paris]. As resistance decreases, the contrast of an MLC display deteriorates. Due to interaction with the internal surface of the display, the specific resistivity of the liquid crystal mixture typically decreases over the lifespan of an MLC display; therefore, high (initial) resistance is crucial for displays that must maintain acceptable resistance values ​​over long operating cycles.

[0014] Besides IPS displays (e.g., Yeo, SD, Paper 15.3: “An LC Display for the TV Application”, SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 758 and 759) and the long-known TN displays, displays utilizing the ECB effect have emerged as so-called VAN (Vertical Alignment Nematic) displays, which are currently one of the three most important new liquid crystal displays, especially for television applications.

[0015] The most important designs that can be mentioned here are: MVA (Multi-Area Vertical Alignment, e.g., Yoshide, H. et al., Paper 3.1: "MVA LCD for Notebook or Mobile PCs...", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book I, pp. 6-9; and Liu, CT et al., Paper 15.1: "A46-inch TFT-LCD HDTV Technology...", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 750-753), and PVA (Pattern Vertical Alignment, e.g., Kim, SangSoo, Paper 15.4: "Super PVA Sets New State-of-the-Art for LCD-TV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II). II, pp. 760-763) and ASV (Advanced Super Viewing Angle, e.g.: Shigeta, Mitzuhiro and Fukuoka, Hirofumi, Paper 15.2: "Development of High Quality LCDTV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 754-757).

[0016] These technologies are compared in their usual forms, such as in Souk, Jun, SID Seminar 2004, Seminar M-6: “Recent Advances in LCD Technology”, Seminar Lecture Notes, M-6 / 1 to M-6 / 26, and Miller, Ian, SID Seminar 2004, Seminar M-7: “LCD-Television”, Seminar Lecture Notes, M-7 / 1 to M-7 / 32. Although the response time of modern ECB displays has been significantly improved through overdrive addressing methods, for example, Kim, Hyeon Kyeong et al., Paper 9.1: “A 57-in. Wide UXGA TFT-LCD for HDTV Application”, SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book I, pp. 106-109, achieving a suitable response time for video, especially in grayscale switching, remains an unsatisfactory problem.

[0017] ECB displays, like ASV displays, use liquid crystal media with negative dielectric anisotropy (Δε), while TN displays and all traditional IPS displays to date use liquid crystal media with positive dielectric anisotropy.

[0018] In this type of liquid crystal display, liquid crystal is used as a dielectric, and its optical properties change reversibly when a voltage is applied.

[0019] Because the operating voltage in displays, specifically those exhibiting the effects mentioned above, should generally be as low as possible, liquid crystal media typically composed primarily of liquid crystal compounds, all of which have the same dielectric anisotropy sign and the highest possible dielectric anisotropy value, are used. Typically, a relatively small proportion of neutral compounds is used, and compounds with the opposite dielectric anisotropy sign to the medium are avoided as much as possible. In the case of liquid crystal media with negative dielectric anisotropy used in ECB displays, compounds with negative dielectric anisotropy are therefore primarily used. The liquid crystal media used generally consists primarily, and often even substantially, of liquid crystal compounds with negative dielectric anisotropy.

[0020] In the media used according to this application, at most a significant amount of dielectric neutral liquid crystal compound and usually only a very small amount or even no dielectric positive compound are generally used, because liquid crystal displays are generally intended to have the lowest possible addressing voltage.

[0021] JP 2006-37054(A) discloses a liquid crystal mixture comprising three compounds of the following formula.

[0022]

[0023] Where R represents C2H5, C3H7, or C4H9.

[0024] And also includes one or more compounds of the following formula

[0025]

[0026] Where (R,R') represents (C3H7,C2H5), (C5H 11 (CH3) or (C5H) 11 (C2H5).

[0027] However, for many practical applications of liquid crystal displays, known liquid crystal media are not stable enough. In particular, their instability to UV radiation and even to conventional backlight radiation leads to significant impairment in electrical properties. Thus, for example, conductivity increases significantly.

[0028] The use of so-called "hindered amine light stabilizers," or HALS for short, has been suggested for stabilizing liquid crystal mixtures.

[0029] For example, WO 2009 / 129911 A1 proposed a method containing a small amount of... 770, a compound of the following formula

[0030]

[0031] Nematic liquid crystal mixtures with negative dielectric anisotropy serve as stabilizers. However, the performance of these liquid crystal mixtures is insufficient for many practical applications. In particular, they are not stable enough for backlighting radiation from common CCFLs (cold cathode fluorescent lamps).

[0032] Similar liquid crystal mixtures are also known, such as EP 2 182 046 A1, WO 2008 / 009417 A1, WO2009 / 021671 A1 and WO 2009 / 115186 A1. However, the use of stabilizers is not mentioned in these.

[0033] According to the disclosures, these liquid crystal mixtures may optionally contain various types of stabilizers, such as phenols and hindered amines (hindered amine light stabilizers, or HALS for short). However, these liquid crystal mixtures are characterized by relatively high threshold voltages and at most moderate stability. In particular, their voltage retention decreases after exposure. Furthermore, yellowing of the color is frequently observed.

[0034] For example, different stabilizers are described in liquid crystal media in JP(S)55-023169(A), JP(H)05-117324(A), WO 02 / 18515 A1 and JP(H)09-291282(A).

[0035] For the purpose of stability, it was also proposed 123, compounds of the following formula.

[0036]

[0037] Mesocrystalline compounds containing one or two HALS units are disclosed in EP 1 1784 442 A1.

[0038] In Ohkatsu, Y., J. of Japan Petroleum Institute, 51, 2008, pp. 191-204, HALS with different substituents on the nitrogen atom are analyzed for their pK. B The values ​​were compared. The following types of structures are disclosed here.

[0039]

[0040]

[0041] The compound TEMPOL with the following formula is known;

[0042]

[0043] For example, it is mentioned in Miéville, P. et al., Angew. Chem. 2010, 122, pp. 6318-6321. It is available from various manufacturers and can be used, for example, as a polymerization inhibitor, and especially in conjunction with UV absorbers, as a light or UV protectant in polyethylene, polystyrene, polyamide precursors, coatings, and PVC.

[0044] In the prior art, liquid crystal media with correspondingly low addressing voltages have relatively low resistivity or low VHR, which often leads to undesirable flicker and / or insufficient transmittance in displays. Furthermore, they are not sufficiently stable to thermal and / or UV exposure, at least if they have correspondingly high polarity, as this is necessary for low addressing voltages.

[0045] On the other hand, the addressing voltage of displays with high VHR in the prior art is usually too high, especially for displays that are not directly or discontinuously connected to the power grid, such as displays for mobile applications.

[0046] In addition, the phase range of the liquid crystal mixture must be wide enough for the desired application of the display.

[0047] The response time of liquid crystal media in displays must be improved, i.e., reduced. This is especially important for displays used in television or multimedia applications. In the past, optimizing the rotational viscosity (γ1) of the liquid crystal media has been repeatedly mentioned as a way to improve response time, i.e., to achieve a medium with the lowest possible rotational viscosity. However, the results achieved in this way are insufficient for many applications, thus it seems necessary to find further optimization methods.

[0048] Sufficient stability of the medium under extreme loads, especially under UV exposure and heating, is extremely important. This can be particularly critical in applications involving displays in mobile devices, such as mobile phones.

[0049] The shortcomings of MLC displays disclosed to date are due to their relatively low contrast ratio, relatively high viewing angle dependence and difficulty in producing grayscale in these displays, as well as their insufficient VHR and their inadequate lifespan.

[0050] Therefore, there remains a huge demand for MLC displays with very high specific resistance, a wide operating temperature range, short response time, and low threshold voltage, which can produce various gray levels and have particularly good and stable VHR. Summary of the Invention

[0051] The object of this invention is to provide MLC displays based on the ECB or IPS effect not only for monitor and TV applications but also for mobile phones and navigation systems. These displays do not have the disadvantages described above, or only have them to a lesser extent, while simultaneously possessing very high resistivity. In particular, for mobile phones and navigation systems, it is essential to ensure their operation at extremely high and extremely low temperatures.

[0052] Surprisingly, it has been found that if a nematic liquid crystal mixture is used in these display elements, the mixture comprising at least one compound of formula I and, in various cases, at least one compound of formula III-O, preferably sub-formula III-O-1 and / or III-O-2, and preferably at least one compound of formula II and / or at least one compound selected from formulas III-1 to III-4 (preferably formula III-3), then it is possible to achieve, especially in ECB displays, a liquid crystal display with a low threshold voltage, short response time, a sufficiently wide nematic phase, an advantageously relatively low birefringence (Δn), good stability against degradation by heat and UV exposure, and a stable high VHR.

[0053] These media are particularly suitable for use in electro-optic displays with active matrix addressing based on the ECB effect and for IPS (in-plane switching) displays.

[0054] Therefore, the present invention relates to liquid crystal media based on mixtures of polar compounds, comprising at least one compound of formula I and one or more compounds of formula III-O, and preferably also comprising one or more compounds of formula II and / or also comprising one or more compounds selected from formulas III-1 to III-4.

[0055] The mixtures according to the invention exhibit a very wide nematic phase range and a clearing point of ≥70°C, a value highly favorable for the capacitance threshold, relatively high retention, good low-temperature stability between -20°C and -30°C, and very low rotational viscosity. The mixtures according to the invention also feature a good clearing point to rotational viscosity ratio and high negative dielectric anisotropy.

[0056] Surprisingly, it has now been discovered that it is possible to realize liquid crystal media with suitable high Δε, suitable nematic phase range and Δn, which do not have the disadvantages of existing materials or at least have these disadvantages only to a significantly reduced extent.

[0057] Surprisingly, it has been found that compounds of formula I, even when used alone without other heat stabilizers, result in considerable, in many cases, sufficient stability of liquid crystal mixtures to UV exposure and heat. This is indeed true, especially in most cases, where the parameter R in the compound of formula I used... 11 O ● Therefore, R in it 11 O ● Compounds of formula I are particularly preferred, and their precise use in liquid crystal mixtures is particularly preferred.

[0058] However, in addition to compounds of Formula I or multiple compounds of Formula I, especially if one or more other compounds (preferably phenolic stabilizers) are added to the liquid crystal mixture, the stability of the liquid crystal mixture to UV exposure and to heat can also be achieved. These other compounds are suitable as heat stabilizers.

[0059] Therefore, the present invention relates to compounds of formula I and to liquid crystal media having a nematic phase and negative dielectric anisotropy, comprising

[0060] a) One or more compounds of formula I, preferably in a concentration range of 1 ppm to 1000 ppm, more preferably from 1 ppm to 500 ppm, and particularly preferably from 1 ppm to 250 ppm.

[0061]

[0062] in

[0063] n represents an integer from 1 to 4, preferably 1, 2, or 3, particularly preferably 1 or 2, and particularly preferably 2.

[0064] m represents (4-n),

[0065] This refers to an organic group having 4 bonding sites, preferably an alkane tetram unit having 1-20 carbon atoms, wherein, except for m groups R 12 It exists outside the molecule, but independently, another H atom can be reacted with R. 12 The substitution, or multiple other H atoms, can be replaced by R. 12 The substitution is preferably a straight-chain alkane tetramethyl unit with a monovalent charge on each of the two terminal C atoms, wherein one or more -CH2- groups can be substituted by -O- or -C(=O)- in such a way that the two O atoms are not directly bonded to each other, or it represents a substituted or unsubstituted aromatic or heteroaromatic hydrocarbon group with a 1-4 valence, wherein, except for m groups R 12 It exists outside the molecule, but independently, another H atom can be reacted with R. 12 The substitution, or multiple other H atoms, can be replaced by R. 12 Replacement

[0066] Z 11 and Z 12 Independently represented by -O-, -(C=O)-, -(NR-). 14 - or a single bond, but not simultaneously representing -O-.

[0067] r and s, independently representing 0 or 1,

[0068] Y 11 To Y14 Each independently represents an alkyl group having 1-4 carbon atoms, preferably methyl or ethyl, preferably both methyl or ethyl, and very particularly preferably methyl, and optionally, also independently, the group pairs (Y) 11 and Y 12 ) and (Y 13 and Y 14 One or two of these groups together represent 3-6 carbon atoms, preferably a divalent group having 5 carbon atoms, and particularly preferably 1,5-pentadiyl.

[0069] R 11 OR 13 O ● Or OH, preferably OR 13 Or O ● O is the preferred choice ● OH, isopropoxy, cyclohexyloxy, acetylphenoxy, phenoxy, and very particularly preferred OH,

[0070] R 12 Each occurrence independently represents H, F, and OR. 14 NR 14 R 15 A straight-chain or branched alkyl chain having 1-20 carbon atoms, wherein one or more -CH2- groups can be substituted with -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted with -O-; or a hydrocarbon group containing cycloalkyl or alkylcycloalkyl units, wherein one or more -CH2- groups can be substituted with -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted with -O-, and one or more H atoms can be substituted with OR 14 、N(R 14 (R) 15 ) or R 16 Substitution; or representing an aromatic or heteroaromatic hydrocarbon group, where one or more H atoms can be ORed. 14 、N(R 14 (R) 15 ) or R 16 Replacement

[0071] R 13Each time it appears, it independently represents a straight-chain or branched alkyl chain having 1-20 C atoms, where one or more -CH2- groups can be substituted with -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted with -O-; or it represents a hydrocarbon group containing cycloalkyl or alkylcycloalkyl units, where one or more -CH2- groups can be substituted with -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted with -O-, and one or more H atoms can be substituted with OR. 14 、N(R 14 (R) 15 ) or R 16 Substitution; or representing an aromatic or heteroaromatic hydrocarbon group, where one or more H atoms can be ORed. 14 、N(R 14 (R) 15 ) or R 16 Replacement

[0072] Or it could be

[0073] (1,4-cyclohexylene), wherein one or more -CH2- groups can be -O-, -CO- or -NR. 14 Substitute with acetylated phenyl, isopropyl, or 3-heptyl.

[0074] R 14 Each time it appears, it independently represents a straight-chain or branched alkyl or acyl group having 1-10 carbon atoms, preferably a n-alkyl group, or an aromatic hydrocarbon group or carboxyl group having 6-12 carbon atoms, preferably under the condition that, in N(R 14 (R) 15 In the case of ), at least one acyl group is present.

[0075] R 15 Each time it appears, it independently represents a straight-chain or branched alkyl or acyl group having 1-10 carbon atoms, preferably a n-alkyl group, or an aromatic hydrocarbon group or carboxyl group having 6-12 carbon atoms, preferably under the condition that, in N(R 14 (R) 15 In the case of ), at least one acyl group is present.

[0076] R 16 Each occurrence independently represents a straight-chain or branched alkyl group having 1-10 carbon atoms. One or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-.

[0077] The prerequisite is that,

[0078] When n=1, R 11 =O ● And -[Z 11 ] r -[Z 12 ] s -=-O-, -(CO)-O-, -O-(CO)-, -O-(CO)-O-, -NR 14 or -NR 14 In the case of -(CO)-,

[0079]

[0080] Not indicating

[0081] Straight-chain or branched alkyl groups having 1-10 carbon atoms, as well as cycloalkyl, cycloalkylalkyl, or alkylcycloalkyl groups, wherein in all these groups, one or more -CH2- groups can be replaced by -O- in such a way that the two O atoms are not directly bonded to each other in the molecule.

[0082] The following compounds are excluded from Formula I.

[0083]

[0084] as well as

[0085] In n=2 and R 11 =OR 13 In the case of R 13 Does not indicate positive C 1-9 -alkyl,

[0086] as well as

[0087] b) One or more compounds of formula III-O

[0088]

[0089] in

[0090] R 31 This refers to an unsubstituted alkyl group having 1-7 carbon atoms, preferably a n-alkyl group, and particularly preferably having 2-5 carbon atoms.

[0091] R 32 This refers to an unsubstituted alkyl group having 1-7 carbon atoms, preferably having 2-5 carbon atoms, or an unsubstituted alkoxy group having 1-6 carbon atoms, preferably having 1, 2, 3, or 4 carbon atoms, or an unsubstituted olefinic group having 2-6 carbon atoms, and...

[0092] i represents 1 or 2,

[0093] as well as

[0094] c) Optionally, and preferably mandatory, one or more compounds of formula II.

[0095]

[0096] in

[0097] R 21 This indicates an unsubstituted alkyl group having 1-7 carbon atoms or an unsubstituted alkenyl group having 2-7 carbon atoms, preferably a n-alkyl group, and particularly preferably having 3, 4, or 5 carbon atoms.

[0098] R 22 Unsubstituted alkenyl groups having 2-7 carbon atoms, preferably having 2, 3, or 4 carbon atoms, more preferably vinyl or 1-propenyl, and particularly vinyl.

[0099] as well as

[0100] d) Optionally, preferably mandatory, one or more compounds selected from formulas III-1 to III-4, preferably compounds of formula III-3.

[0101]

[0102] in

[0103] R 31 This refers to an unsubstituted alkyl group having 1-7 carbon atoms, preferably a n-alkyl group, and particularly preferably having 2-5 carbon atoms.

[0104] R 32 This indicates an unsubstituted alkyl group having 1-7 carbon atoms, preferably having 2-5 carbon atoms, or an unsubstituted alkoxy group having 1-6 carbon atoms, preferably having 2, 3, or 4 carbon atoms.

[0105] m, n, and o each, independently, represent 0 or 1.

[0106] The following implementation schemes are preferred:

[0107] express

[0108] (Benzene-1,2,4,5-tetrayl) or -CH2-(CH)-[CH2] q -(CH)-CH2- or

[0109] >CH-[CH2] p -CH<, (where p∈{0, 1, 2, 3, 4, 5 to 18} and q∈{0, 1, 2, 3 to 16}) or

[0110] express

[0111] >CH-[CH2] p -CH2- (where p∈{0, 1, 2, 3, 4, 5 to 18} or

[0112] express

[0113] -CH2-[CH2] p -CH2- (where p∈{0, 1, 2, 3, 4, 5 to 18}, propane-1,2-diyl, butane-1,2-diyl, ethane-1,2-diyl,

[0114] (1,4-Phenylidene)

[0115] (1,2-phenylene) or

[0116] (1,4-cyclohexylene).

[0117] In this application, all elements include their respective isotopes. In particular, one or more H atoms in a compound may be replaced by D atoms, and this is particularly preferred in some embodiments. The corresponding high degree of deuteration of the compounds enables, for example, the detection and identification of the compounds. This is very helpful in some cases, especially in the case of compounds of formula I.

[0118] In this application,

[0119] Alkyl groups are particularly preferred to be straight-chain alkyl groups, especially CH3-, C2H5-, n-C3H7-, n-C4H9- or n-C5H 11 -,as well as

[0120] Alkenyl is particularly preferred to represent CH2=CH-, E-CH3-CH=CH-, CH2=CH-CH2-CH2-, E-CH3-CH=CH-CH2-CH2-, or E-(n-C3H7)-CH=CH-.

[0121] The liquid crystal medium according to this application preferably contains a total of 1 ppm to 1000 ppm, more preferably 1 ppm to 500 ppm, even more preferably 1 ppm to 250 ppm, more preferably 200 ppm, and very particularly preferably 1 ppm to 100 ppm of a compound of formula I.

[0122] The concentration of the compound of Formula I in the liquid crystal medium according to the invention is preferably 90 ppm or less, particularly preferably 50 ppm or less. The concentration of the compound of Formula I in the liquid crystal medium according to the invention is very particularly preferably 10 ppm or more up to 80 ppm or less.

[0123] In a preferred embodiment of the invention, in the compound of formula I,

[0124] express (Benzene-1,2,4,5-tetramethyl) or

[0125] express (Benzene-1,3,5-trimethyl) or

[0126] This represents -(CH2-)2, -(CH2-)4, -(CH2-)6, -(CH2-)8,

[0127] Propane-1,2-diyl, Butane-1,2-diyl, Ethane-1,2-diyl

[0128] (1,4-phenylene)

[0129] (1,3-phenylene)

[0130] (1,2-phenylene) or

[0131] (trans-1,4-cyclohexylene) and / or

[0132] -[Z 11 -] r -[Z 12 -] s - Each time it appears, it independently represents -O-, -(C=O)-O- or -O-(C=O)-, -(NR 14 - or single bond, preferably -O- or -(C=O)-O- or -O-(C=O)-, and / or

[0133] R 11 Indicates -O ● OH or OR 13 Preferably:

[0134] -O ● , -O-CH(-CH3)2, -O-CH(-CH3)(-CH2)3-CH3, -O-CH(-C2H5)(-CH2)3-CH3,

[0135] and / or

[0136] R 12 If present, it indicates an alkyl or alkoxy group, and / or

[0137] R 13 It represents isopropyl or 3-heptyl, acetylphenyl or cyclohexyl.

[0138] In a preferred embodiment of the invention, in the compound of formula I, the group

[0139]

[0140] Each occurrence represents an independent entity.

[0141]

[0142] Preferred

[0143]

[0144] In a particularly preferred embodiment of the invention, all groups present in the compound of formula I...

[0145]

[0146] They have the same meaning.

[0147] These compounds are well-suited as stabilizers in liquid crystal mixtures. In particular, they stabilize the VHR of the mixture upon exposure to UV.

[0148] In a preferred embodiment of the invention, the medium according to the invention comprises, in various cases, one or more compounds selected from formulas I-1 to I-9, preferably one or more compounds of formula I selected from formulas I-1 to I-4.

[0149]

[0150]

[0151]

[0152] The parameters have the meanings shown in Equation I above, and

[0153] t represents 1 to 12 integers.

[0154] R 17This indicates a straight-chain or branched alkyl chain with 1-12 carbon atoms, where one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-. Alternatively, it can indicate an aromatic or heteroaromatic hydrocarbon group, where one or more H atoms can be replaced by OR. 14 、N(R 14 (R) 15 ) or R 16 Replacement.

[0155] In a more preferred embodiment of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formulas I-1a-1 to I-8a-1:

[0156]

[0157]

[0158]

[0159] In a more preferred embodiment of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formula I-2a-1 and I-2a-2:

[0160]

[0161] In an alternative preferred embodiment of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formula I-1b-1 and I-1b-2:

[0162]

[0163] In an alternative preferred embodiment of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formula I-1c-1 and I-1c-2:

[0164]

[0165] In other alternative preferred embodiments of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formula I-1d-1 to I-1d-4:

[0166]

[0167] In other alternative preferred embodiments of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formula I-3d-1 to I-3d-8:

[0168]

[0169]

[0170] In other alternative preferred embodiments of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formula I-4d-1 and I-4d-2:

[0171]

[0172] In other alternative preferred embodiments of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formulas I-1e-1 and I-1e-2:

[0173]

[0174] In other alternative preferred embodiments of the invention, the medium according to the invention comprises, in various cases, one or more compounds of formula I selected from compounds of formulas I-5e-1 to I-8e-1:

[0175]

[0176] In addition to compounds of Formula I or their preferred sub-forms, the medium according to the invention preferably comprises one or more dielectrically neutral compounds of Formula II, the total concentration of which preferably ranges from 5% or more to 90% or less, preferably from 10% or more to 80% or less, and particularly preferably from 20% or more to 70% or less.

[0177] The medium according to the invention preferably contains one or more compounds selected from formulas III-1 to III-4 in a total concentration ranging from 10% or more to 80% or less, preferably from 15% or more to 70% or less, and particularly preferably from 20% or more to 60% or less.

[0178] The medium according to the invention particularly preferably contains

[0179] Compounds comprising one or more of formula III-O in a total concentration ranging from 5% or more to 40% or less, preferably from 10% or more to 30% or less, and / or

[0180] Comprising compounds of formula III-1 in a total concentration ranging from 5% or more to 30% or less, and / or

[0181] Comprising compounds of formula III-2 in a total concentration ranging from 3% or more to 30% or less, and / or

[0182] Comprising compounds of formula III-3 in a total concentration ranging from 5% or more to 30% or less, and / or

[0183] Compounds containing one or more of formula III-4 in a total concentration ranging from 1% or more to 30% or less.

[0184] Preferred compounds of formula II are selected from formulas II-1 and II-2, with a preference for compounds of formula II-1.

[0185]

[0186] in

[0187] Alkyl refers to an alkyl group having 1-7 carbon atoms, preferably 2-5 carbon atoms.

[0188] alkenyl indicates an alkenyl group having 2-5 carbon atoms, preferably 2-4 carbon atoms, and particularly preferably 2 carbon atoms.

[0189] 'alkenyl' indicates an alkenyl group having 2-5 C atoms, preferably 2-4 C atoms, and particularly preferably 2-3 C atoms.

[0190] The medium according to the invention comprises one or more compounds of formula III-O-1 and III-O-2, preferably one or more compounds of each of formula III-O-1 and III-O-2.

[0191]

[0192] The parameters have the meanings given in Equation III-O above, and preferably...

[0193] R 31 This indicates an alkyl group having 2-5 carbon atoms, preferably 3-5 carbon atoms, and...

[0194] R 32 It indicates an alkyl or alkoxy group having 2-5 carbon atoms, preferably an alkoxy group having 1 carbon atom or having 2-4 carbon atoms, or an olefinic group having 2-4 carbon atoms.

[0195] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds of formula III-1, preferably one or more compounds selected from compounds of formulas III-1-1 and III-1-2.

[0196]

[0197] The parameters have the meanings given above for III-1, and are preferably...

[0198] R 31 This indicates an alkyl group having 2-5 carbon atoms, preferably 3-5 carbon atoms, and...

[0199] R 32 It indicates an alkyl or alkoxy group having 2-5 carbon atoms, preferably an alkoxy group having 2-4 carbon atoms, or an olefinic group having 2-4 carbon atoms.

[0200] The medium according to the invention preferably comprises one or more compounds of formula III-2, more preferably one or more compounds selected from compounds of formula III-2-1 and III-2-2.

[0201]

[0202] The parameters have the meanings given above for III-2, and are preferably...

[0203] R 31 This indicates an alkyl group having 2-5 carbon atoms, preferably 3-5 carbon atoms, and...

[0204] R 32 It indicates an alkyl or alkoxy group having 2-5 carbon atoms, preferably an alkoxy group having 2-4 carbon atoms, or an olefinic group having 2-4 carbon atoms.

[0205] In a particularly preferred embodiment of the invention, the medium according to the invention comprises one or more compounds of formula III-3, preferably one or more selected from formulas III-3-1 and III-3-2, and very particularly preferably compounds of formula III-3-2.

[0206]

[0207] The parameters have the meanings given above for III-3, and are preferably...

[0208] R 31 This indicates an alkyl group having 2-5 carbon atoms, preferably 3-5 carbon atoms, and...

[0209] R 32 It indicates an alkyl or alkoxy group having 2-5 carbon atoms, preferably an alkoxy group having 2-4 carbon atoms, or an olefinic group having 2-4 carbon atoms.

[0210] In a preferred embodiment, the medium according to the invention comprises one or more compounds of formula II selected from formula II-1 and II-2.

[0211] In a different preferred embodiment, the medium according to the invention does not contain compounds of formula II.

[0212] In a further preferred embodiment, the medium comprises one or more compounds of formula IV.

[0213]

[0214] in

[0215] R 41 This indicates an alkyl group having 1-7 carbon atoms, preferably having 2-5 carbon atoms, and

[0216] R 42 The term indicates an alkyl group having 1-7 carbon atoms or an alkoxy group having 1-6 carbon atoms, preferably having 2-5 carbon atoms.

[0217] In a further preferred embodiment, the medium comprises one or more compounds of formula V.

[0218]

[0219] in

[0220] R 51 and R 52 Independently, having R 21 and R 22 The given meaning, and preferably refers to alkyl groups having 1-7 carbon atoms, preferably n-alkyl groups, particularly preferably n-alkyl groups having 1-5 carbon atoms; alkoxy groups having 1-7 carbon atoms, preferably n-alkoxy groups, particularly preferably n-alkoxy groups having 2-5 carbon atoms; and alkoxyalkyl, alkenyl, or alkenyloxy groups having 2-7 carbon atoms, preferably 2-4 carbon atoms, preferably alkenyloxy groups.

[0221]

[0222] to

[0223]

[0224] If they exist, they are represented independently of each other.

[0225] Preferred

[0226]

[0227] Preferably,

[0228] express And, if it exists,

[0229] Preferred representation

[0230] Z 51 To Z 53 Each can independently represent -CH2-CH2-, -CH2-O-, -CH=CH-, -C≡C-, -COO-, or a single bond, preferably -CH2-CH2-, -CH2-O-, or a single bond, and particularly preferably a single bond.

[0231] p and q each represent 0 or 1 independently.

[0232] (p+q) preferably represents 0 or 1.

[0233] The medium according to the invention preferably comprises the following compounds in total concentration:

[0234] 10-60% by weight of one or more compounds selected from formulas III-O and III-1 to III-4 and / or

[0235] 30-80% by weight of one or more compounds of formula IV and / or V,

[0236] The total content of all compounds in the medium is 100%.

[0237] In a particularly preferred embodiment, the medium according to the invention comprises one or more compounds selected from those of formulas OH-1 to OH-6.

[0238]

[0239] These compounds are well-suited for the thermal stability of media.

[0240] In another preferred embodiment of the invention, the medium according to the invention comprises, in particular, one or more wherein R 11 Or at least one R 11 At least one of them represents O ● Compounds of formula I, if they do not contain phenolic compounds, especially those selected from formulas OH-1 to OH-6, also have sufficient stability in these media.

[0241] In a further preferred embodiment of the invention, the medium according to the invention comprises, in at least various cases, one or more groups R of a compound of formula I. 11Compounds of Formula I that have a different meaning from other compounds of Formula I.

[0242] The present invention also relates to an electro-optic display or electro-optic assembly comprising a liquid crystal medium according to the invention. Preferred are electro-optic displays based on the VA or ECB effect, and particularly preferred are displays addressed using an active matrix addressing device.

[0243] Therefore, the present invention also relates to the use of the liquid crystal medium according to the invention in electro-optic displays or electro-optic elements, and to a method for preparing the liquid crystal medium according to the invention, characterized in that: one or more compounds of formula I are mixed with one or more compounds of formula II, preferably one or more compounds of sub-formula II-1, and one or more other compounds, preferably selected from compounds of formulas III-1 to III-4 and IV and / or V.

[0244] Furthermore, the present invention relates to a method for stabilizing liquid crystal media, comprising one or more compounds of formula III-O, optionally one or more compounds of formula II and / or one or more compounds selected from formulas III-1 to III-4, characterized in that one or more compounds of formula I are added to the media.

[0245] In a further preferred embodiment, the medium comprises one or more compounds of formula IV, selected from compounds of formula IV-1 and IV-2.

[0246]

[0247] in

[0248] alkyl and alkyl', independently of each other, represent alkyl groups having 1-7 carbon atoms, preferably having 2-5 carbon atoms.

[0249] alkoxy means an alkoxy group having 1-5 carbon atoms, preferably 2-4 carbon atoms.

[0250] In a further preferred embodiment, the medium comprises one or more compounds of formula V, selected from compounds of formulas V-1 to V-7 and VI-1 to VI-3, preferably selected from compounds of formulas V-1 to V-5.

[0251]

[0252]

[0253] The parameters have the meanings given by equation V above, and

[0254] Y 5 Indicates H or F, and preferably

[0255] R51 Indicates an alkyl group having 1-7 carbon atoms or 2-7 carbon atoms, and

[0256] R 52 The term indicates an alkyl group having 1-7 carbon atoms, an alkenyl group having 2-7 carbon atoms, or an alkoxy group having 1-6 carbon atoms, preferably an alkyl or alkenyl group, with alkenyl group being particularly preferred.

[0257] In a further preferred embodiment, the medium comprises one or more compounds of formula V-1 selected from formulas V-1a and V-1b, preferably compounds of formula V-1b.

[0258]

[0259] in

[0260] alkyl and alkyl', independently of each other, represent alkyl groups having 1-7 carbon atoms, preferably having 2-5 carbon atoms.

[0261] alkoxy refers to an alkoxy group having 1-5 carbon atoms, preferably 2-4 carbon atoms.

[0262] In a further preferred embodiment, the medium comprises one or more compounds of formula V-3 selected from compounds of formula V-3a and V-3b.

[0263]

[0264] in

[0265] alkyl and alkyl', independently of each other, represent alkyl groups having 1-7 carbon atoms, preferably having 2-5 carbon atoms, and

[0266] alkenyl indicates an alkenyl group having 2-7 carbon atoms, preferably having 2-5 carbon atoms.

[0267] In a further preferred embodiment, the medium comprises one or more compounds of formula V-4 selected from compounds of formula V-4a and V-4b.

[0268]

[0269] in

[0270] alkyl and alkyl', independently of each other, represent alkyl groups having 1-7 carbon atoms, preferably having 2-5 carbon atoms.

[0271] In a further preferred embodiment, the medium comprises one or more compounds selected from formula III-4, preferably formula III-4-a.

[0272]

[0273] in

[0274] alkyl and alkyl', independently of each other, represent alkyl groups having 1-7 carbon atoms, preferably having 2-5 carbon atoms.

[0275] The liquid crystal medium according to the present invention may also contain one or more chiral compounds.

[0276] A particularly preferred embodiment of the present invention satisfies one or more of the following conditions:

[0277] The acronyms are explained in Tables A through C and illustrated in Table D.

[0278] i. The birefringence of the liquid crystal medium is 0.060 or higher, particularly preferably 0.070 or higher.

[0279] ii. The birefringence of the liquid crystal medium is 0.130 or lower, particularly preferably 0.120 or lower.

[0280] iii. The birefringence of the liquid crystal medium is in the range of 0.090 or higher to 0.120 or lower.

[0281] iv. The negative dielectric anisotropy value of the liquid crystal medium is 2.0 or higher, particularly preferably 3.0 or higher.

[0282] v. The negative dielectric anisotropy value of the liquid crystal medium is 5.5 or lower, particularly preferably 4.0 or lower.

[0283] vi. The negative dielectric anisotropy value of the liquid crystal medium is in the range of 2.5 or higher to 3.8 or lower.

[0284] vii. The liquid crystal medium comprises one or more compounds of Formula II, particularly preferably selected from the following subtypes:

[0285]

[0286] Wherein, alkyl has the meaning shown above, and preferably, in each case, it independently represents an alkyl group having 1-6 C atoms, more preferably having 2-5 C atoms, and particularly preferably a n-alkyl group.

[0287] viii. The total concentration of the compound of formula II in the entire mixture is 25% or more, preferably 30% or more, and preferably in the range of 25% or more to 49% or less, particularly preferably in the range of 29% or more to 47% or less, and very particularly preferably in the range of 37% or more to 44% or less.

[0288] ix. The liquid crystal medium comprises one or more compounds selected from the following formulas: CC-nV and / or CC-n-Vm, particularly preferably compounds of formula II such as CC-3-V, preferably at a concentration of up to 50% or less, particularly preferably at a concentration of up to 42% or less, and optionally also comprising CC-3-V1, preferably at a concentration of up to 15% or less, and / or CC-4-V, preferably at a concentration of up to 20% or less, particularly preferably at a concentration of up to 10% or less.

[0289] The total concentration of the x-type CC-3-V compound in the entire mixture is 20% or more, preferably 25% or more.

[0290] xi. The proportion of compounds of formula III-1 to III-4 in the overall mixture is 50% or more, and preferably 75% or less.

[0291] xii. The liquid crystal medium is substantially composed of compounds of formulas I, II, III-1 to III-4, IV and V, preferably substantially composed of compounds of formulas I, II and III-1 to III-4.

[0292] xiii. The liquid crystal medium contains one or more compounds of formula IV, preferably 5% or more of the total concentration, particularly 10% or more, and very particularly preferably 15% or more up to 40% or less.

[0293] The present invention relates to an electro-optic display with active matrix addressing based on the VA or ECB effect, characterized in that it comprises a liquid crystal medium according to the present invention as a dielectric.

[0294] The liquid crystal mixture preferably has a nematic phase range of at least 80 degrees and a maximum thickness of 30 mm at 20°C. 2 ·s -1 Flow viscosity ν 20 .

[0295] The liquid crystal mixture according to the invention has a Δε of -0.5 to -8.0, particularly -1.5 to -6.0, and very particularly preferably -2.0 to -5.0, where Δε represents dielectric anisotropy.

[0296] The rotational viscosity γ1 is preferably 120 mPa·s or less, especially 100 mPa·s or less.

[0297] The mixtures according to the invention are suitable for all VA-TFT applications, such as VAN, MVA, (S)-PVA, and ASV. They are further suitable for IPS (in-plane switching), FFS (edge ​​field switching), and PALC applications with negative Δε.

[0298] In the display according to the invention, the nematic liquid crystal mixture typically comprises two components A and B, each composed of one or more single compounds.

[0299] The liquid crystal medium according to the invention preferably comprises 4 to 15, particularly 5 to 12, and especially preferably 10 or fewer compounds. These compounds are preferably selected from compounds of formulas I, II and III-1 to III-4, and / or IV and / or V.

[0300] The liquid crystal medium according to the invention may optionally further include more than 18 compounds. In this case, they preferably contain 18 to 25 compounds.

[0301] In addition to the compounds of formulas I to V, other components may be present, for example, in a content of up to 45%, but preferably up to 35%, and especially up to 10%, of the entire mixture.

[0302] The liquid crystal medium according to the invention may optionally contain a dielectric positive component, the total concentration of which is preferably 10% or less based on the entire medium.

[0303] In a preferred embodiment, the liquid crystal medium according to the invention comprises, based on the total mixture: 10 ppm or more to 1000 ppm or less, preferably 50 ppm or more to 500 ppm or less, particularly preferably 100 ppm or more to 400 ppm or less, and very particularly preferably 150 ppm or more to 300 ppm or less of the compound of formula I.

[0304] 20% or more to 60% or less, preferably 25% or more to 50% or less, particularly preferably 30% or more to 45% or less of the compounds of formula II; and

[0305] 50% or more to 70% or less of compounds of formula III-1 to III-4.

[0306] In a preferred embodiment, the liquid crystal medium according to the invention comprises compounds selected from those of formulas I, II, III-1 to III-4, IV and V, preferably compounds selected from those of formulas I, II and III-1 to III-4; these compounds are preferably mainly, particularly preferably substantially and very particularly preferably almost entirely composed of compounds of the stated chemical formulas.

[0307] The liquid crystal medium according to the invention preferably has a nematic phase of at least -20°C or lower up to 70°C or higher in each case, particularly preferably -30°C or lower up to 80°C or higher, very particularly preferably -40°C or lower up to 85°C or higher, and most preferably -40°C or lower up to 90°C or higher.

[0308] Here, the term "having a nematic phase" means, on the one hand, that no smectic phase and crystallization are observed at the corresponding temperature at low temperatures, and on the other hand, that no clarification occurs upon heating from the nematic phase. Low-temperature studies are conducted in a flow viscometer at the corresponding temperature and verified by storing the medium in a test chamber with a chamber thickness corresponding to the electro-optic application for at least 100 hours. If the medium exhibits stability for 1000 hours or more at -20°C in the corresponding test chamber, it is considered stable at that temperature. The corresponding times are 500 hours and 250 hours at -30°C and -40°C, respectively. At high temperatures, the clearing point is measured in a capillary using conventional methods.

[0309] In a preferred embodiment, the liquid crystal medium according to the invention is characterized by an optical anisotropy value in the medium to low range. The birefringence value is preferably in the range of 0.065 or greater to 0.130 or less, particularly preferably in the range of 0.080 or greater to 0.120 or less, and very particularly preferably in the range of 0.085 or greater to 0.110 or less.

[0310] In this embodiment, the liquid crystal medium according to the invention has negative dielectric anisotropy and a relatively high absolute value of dielectric anisotropy (|Δε|), which is preferably in the range of 2.7 or greater to 5.3 or less, preferably to 4.5 or less, preferably 2.9 or greater to 4.5 or less, particularly preferably 3.0 or greater to 4.0 or less, and very particularly preferably 3.5 or greater to 3.9 or less.

[0311] The liquid crystal medium according to the invention has a relatively low threshold voltage value (V0), in the range of 1.7V or greater to 2.5V or less, preferably 1.8V or greater to 2.4V or less, particularly preferably 1.9V or greater to 2.3V or less, and very particularly preferably 1.95V or greater to 2.1V or less.

[0312] In a further preferred embodiment, the liquid crystal medium according to the invention preferably has a relatively low average dielectric anisotropy value (ε). 平均 ≡(ε || +2ε ⊥ ) / 3), which is preferably in the range of 5.0 or greater to 7.0 or less, more preferably from 5.5 or greater to 6.5 or less, more preferably from 5.7 or greater to 6.4 or less, particularly preferably from 5.8 or greater to 6.2 or less, and very particularly preferably from 5.9 or greater to 6.1 or less.

[0313] Furthermore, the liquid crystal medium according to the present invention has a high VHR value in the liquid crystal cell.

[0314] In a newly filled liquid crystal cell at 20°C, these values ​​are greater than or equal to 95%, preferably greater than or equal to 97%, particularly preferably greater than or equal to 98%, and very particularly preferably greater than or equal to 99% in the cell; and in a cell at 100°C, after 5 minutes in an oven, these values ​​are greater than or equal to 90%, preferably greater than or equal to 93%, particularly preferably greater than or equal to 96%, and very particularly preferably greater than or equal to 98%.

[0315] Typically, liquid crystal media with low addressing voltage or threshold voltage have a lower VHR than liquid crystal media with higher addressing voltage or threshold voltage, and vice versa.

[0316] These preferred values ​​of various physical properties are also preferably maintained in each case by being combined with each other through the medium according to the invention.

[0317] In this application, the term "compound" is also written as "(one or more) compounds" unless otherwise expressly stated, referring not only to one but also to multiple compounds.

[0318] Unless otherwise stated, in different cases, the individual compounds are generally used in the mixture at a concentration of 1% or more up to 30% or less, preferably 2% or more up to 30% or less, and particularly preferably 3% or more up to 16% or less.

[0319] In a preferred embodiment, the liquid crystal medium according to the present invention comprises:

[0320] Compounds of formula I,

[0321] One or more compounds of formula II, preferably selected from compounds of formula CC-nV and CC-n-Vm, preferably CC-3-V, CC-3-V1, CC-4-V and CC-5-V, particularly preferably selected from compounds CC-3-V, CC-3-V1 and CC-4-V, very particularly preferably compound CC-3-V, and optionally another (one or more) compounds CC-4-V and / or CC-3-V1,

[0322] One or more compounds of formula III-1-1, preferably of formula CY-n-Om, selected from compounds of formula CY-3-O2, CY-3-O4, CY-5-O2 and CY-5-O4.

[0323] One or more compounds of formula III-1-2, preferably selected from formulas CCY-nm and CCY-n-Om, more preferably compounds of formula CCY-n-Om, and more preferably compounds of formulas CCY-3-O2, CCY-2-O2, CCY-3-O1, CCY-3-O3, CCY-4-O2, CCY-3-O2, and CCY-5-O2.

[0324] Optionally, preferably mandatory, one or more compounds of formula III-2-2, preferably of formula CLY-n-Om, and more preferably compounds selected from formula CLY-2-O4, CLY-3-O2, and CLY-3-O3.

[0325] One or more compounds of formula III-3-2, preferably of formula CPY-n-Om, and more preferably compounds selected from formulas CPY-2-O2 and CPY-3-O2, CPY-4-O2 and CPY-5-O2.

[0326] One or more compounds of formula III-4, preferably of formula PYP-nm, and more preferably compounds selected from formulas PYP-2-3 and PYP-2-4.

[0327] For the purposes of this invention, the following definitions apply in connection with the description of the composition components, unless otherwise stated in separate instances:

[0328] - "Contains": The concentration of the component discussed in the composition is preferably 5% or more, particularly preferably 10% or more, and very particularly preferably 20% or more.

[0329] - "Mainly composed of": The concentration of the component discussed in the composition is preferably 50% or greater, particularly preferably 55% or greater, and very particularly preferably 60% or greater.

[0330] - "consisting essentially of": The concentration of the component discussed in the composition is preferably 80% or greater, particularly preferably 90% or greater, and very particularly preferably 95% or greater, and

[0331] - "consisting almost entirely of": The concentration of the component discussed in the composition is preferably 98% or greater, particularly preferably 99% or greater, and very particularly preferably 100.0%.

[0332] This applies both to a medium being a composition having its components, which can be ingredients and compounds, and to a component having its components, which are components of the compounds. The term "comprising" is used only with respect to the concentration of a single compound relative to the entire medium: the concentration of the compound in question is preferably 1% or greater, particularly preferably 2% or greater, and very particularly preferably 4% or greater.

[0333] For the purposes of this invention, “≤” means less than or equal to, preferably less than, and “≥” means greater than or equal to, preferably greater than.

[0334] For the purposes of this invention,

[0335]

[0336] Represents trans-1,4-cyclohexyl, and

[0337]

[0338] It represents 1,4-phenylene.

[0339] For the purposes of this invention, the term "positive dielectric compound" refers to a compound with Δε > 1.5, the term "neutral dielectric compound" refers to those wherein -1.5 ≤ Δε ≤ 1.5, and the term "negative dielectric compound" refers to those wherein Δε < -1.5. The dielectric anisotropy of the compounds is determined herein by dissolving 10% of the compound in a liquid crystal substrate and, in each case, measuring the capacitance of the resulting mixture at 1 kHz in at least one test cell with a cell thickness of 20 μm and having both vertical and horizontal surfaces arranged along the surface. The measurement voltage is typically from 0.5 V to 1.0 V, but is always below the capacitance threshold of the respective liquid crystal mixtures studied.

[0340] The host mixtures for the dielectric positive and dielectric neutral compounds were ZLI-4792, and the host mixture for the dielectric negative compounds was ZLI-2857, both from MerckKGaA, Germany. The values ​​for each compound under study were obtained by extrapolating the change in dielectric constant of the host mixture after the addition of the compound under study to 100% of the total compound used. The compound under study was dissolved in the host mixture at 10%. If the solubility of the substance was too low for this purpose, the concentration was gradually halved until the study could be carried out at the desired temperature.

[0341] The liquid crystal medium according to the invention may, if desired, contain other additives in conventional amounts, such as stabilizers and / or pleochroic dyes and / or chiral dopants. The total amount of these additives is preferably 0% or more to 10% or less based on the total amount of the mixture, particularly preferably 0.1% or more to 6% or less. The concentration of each compound used is preferably 0.1% or more to 3% or less. The concentrations of these and similar additives are generally not considered when describing the concentrations and concentration ranges of the liquid crystal compounds in the liquid crystal medium.

[0342] In a preferred embodiment, the liquid crystal medium according to the invention comprises a polymer precursor containing one or more reactive compounds, preferably reactive mesomorphs, and, if desired, other additives in conventional amounts, such as polymerization initiators and / or polymerization moderators. The total amount of these additives is used in quantities of 0% or more to 10% or less, preferably 0.1% or more to 2% or less, based on the total amount of the mixture. The concentrations of these and similar additives are not considered when describing the concentrations and concentration ranges of the liquid crystal compounds in the liquid crystal medium.

[0343] The composition comprises a variety of compounds, preferably 3 or more to 30 or fewer, particularly preferably 6 or more to 20 or fewer, and very particularly preferably 10 or more to 16 or fewer, which are mixed in a conventional manner. Typically, the desired amount of the component used in a small quantity is dissolved in the component constituting the main component of the mixture. This is advantageously carried out at elevated temperatures. If the selected temperature is above the clearing point of the main component, the completion of the dissolution operation can be observed particularly easily. However, liquid crystal mixtures can also be prepared in other conventional ways, such as using premixing or from a so-called "multi-bottle system".

[0344] The mixtures according to the invention exhibit a very wide nematic phase range with a clearing point of 65°C or higher, a very favorable capacitance threshold, a high retention value, and very good low-temperature stability at both -30°C and -40°C. Furthermore, the mixtures according to the invention are characterized by a low rotational viscosity γ1.

[0345] It will be apparent to those skilled in the art that the medium according to the invention for use in VA, IPS, FFS or PALC displays may also contain compounds in which, for example, H, N, O, Cl, F have been replaced by the corresponding isotopes.

[0346] The structure of the liquid crystal display according to the present invention corresponds to a conventional geometry, as described, for example, in EP-A 0240 379.

[0347] The liquid crystal phases according to the invention can be modified by means of suitable additives so that they can be used in any type of LCD display disclosed to date, such as ECB, VAN, IPS, GH or ASM-VA LCD displays.

[0348] Table E below shows possible dopants that can be added to the mixtures according to the invention. If the mixture contains one or more dopants, it(s) is used in an amount of 0.01-4%, preferably 0.1-1.0%.

[0349] Table F below shows stabilizers that can be added, for example, to mixtures according to the invention, preferably in amounts of 0.01-6%, particularly 0.1-3%.

[0350] For the purposes of this invention, all concentrations, unless otherwise expressly stated, are expressed as weight percentages and, unless otherwise expressly stated, are related to the respective mixtures or mixture components.

[0351] All temperature values ​​described in this application, such as melting point T(C,N), smectic phase (S) to nematic phase (N) transformation T(S,N) and clearing point T(N,I), are expressed in degrees Celsius (°C), and all temperature differences are expressed accordingly in degrees of difference (° or degrees), unless otherwise expressly stated.

[0352] For the purposes of this invention, the term “threshold voltage” refers to the capacitance threshold (V0), also known as the Freedericks threshold, unless otherwise explicitly stated.

[0353] All physical properties were determined according to and have been determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", status Nov. 1997, Merck KGaA, Germany, and applied to a temperature of 20°C, and Δn was determined at 589 nm, and Δε was determined at 1 kHz, unless otherwise explicitly stated in different cases.

[0354] Electro-optical properties, such as threshold voltage (V0) (capacitive measurement), which is a switching behavior, were determined in a test chamber manufactured by Merck Japan. The test chamber has a soda-lime glass substrate and is constructed using polyimide alignment layers (SE-1211 and diluent **26 (mixed ratio 1:1, both from Nissan Chemicals, Japan) in an ECB or VA configuration. These alignment layers have been rubbed perpendicularly to each other, resulting in vertical alignment of the liquid crystal. The transparent, substantially square ITO electrode has a surface area of ​​1 cm². 2 .

[0355] Unless otherwise stated, chiral dopants are not added to the liquid crystal mixture used, but the latter is particularly suitable for applications where such doping is required.

[0356] VHR was measured in a test chamber manufactured by Merck Japan. The chamber has a soda-lime glass substrate and is constructed using a 50 nm thick polyimide layer (AL-3046, from Japan Synthetic Rubber), which has been rubbed perpendicularly to each other. The layer thickness is a uniform 6.0 μm. The surface area of ​​the transparent ITO electrode is 1 cm². 2 .

[0357] At 20°C (VHR) 20 ) and after 5 minutes in an oven at 100°C (VHR) 100 VHR was measured using a commercially available Autronic Melchers instrument from Germany. The voltage used had a frequency of 60 Hz.

[0358] The accuracy of VHR measurements depends on the individual VHR values. Accuracy decreases as the value decreases. The deviations typically observed across different orders of magnitude are summarized in the table below.

[0359]

[0360] Stability to UV radiation was studied using the "Suntest CPS," a commercial instrument from Heraeus, Germany. The sealed test chamber was irradiated for 2.0 hours without additional heating. The irradiation power in the 300nm-800nm ​​wavelength range was 765W / m. 2 V. A UV “truncation” filter with a 310 nm edge wavelength was used to simulate the so-called window glass pattern. In each series of tests, at least four test boxes were studied for each condition, and the individual results are described as the average of the corresponding single measurements.

[0361] The decrease in voltage retention ratio (ΔVHR) typically formed by exposure (e.g., by UV radiation through LCD backlight) is determined according to the following equation (1):

[0362] ΔVHR(t)=VHR(t)-VHR(t=0) (1).

[0363] Besides VHR, another characteristic measure that can characterize the conductivity of liquid crystal mixtures is ion density. High ion density values ​​often lead to display malfunctions such as image retention and flicker. Ion density is preferably measured in a test chamber manufactured by Merck Japan Ltd. This test chamber has a substrate made of soda-lime glass and is designed with a polyimide alignment layer (AL-3046, obtained from Japan Synthetic Rubber) with a polyimide layer thickness of 40 nm. The liquid crystal mixture has a uniform layer thickness of 5.8 μm. Additionally, an annular transparent ITO electrode with a protective ring has an area of ​​1 cm². 2 The accuracy of the measurement method is approximately ±15%. Before filling with the relevant liquid crystal mixture, the box is dried overnight in an oven at 120°C.

[0364] Ion density was measured using commercially available instruments from TOYO, Japan. The measurement method is essentially similar to the cyclic voltammetry method described in M. Inoue, “Recent Measurement of Liquid Crystal Material Characteristics”, Proceedings IDW 2006, LCT-7-1, 647. In this method, the applied DC voltage varies between positive and negative maximum values ​​according to a pre-defined triangular distribution. A measurement cycle is formed by the complete operation of this distribution. If the applied voltage is large enough to allow ions in the electric field to move to the corresponding electrode, an ion current is generated due to ion discharge. The amount of charge transferred here is typically several pC to several nC. This necessitates highly sensitive detection, which can be achieved using the aforementioned instrument. The results are described in the current / voltage curves. A peak appears at a voltage lower than the threshold voltage of the liquid crystal mixture, confirming the ion current. The ion density value of the studied mixture is obtained by integrating the peak area. Four test boxes were measured for each mixture. The repetition frequency of the triangular voltage is 0.033 Hz, the measurement temperature is 60 °C, and the maximum voltage is ±3 V to ±10 V, depending on the order of dielectric anisotropy of the relevant mixture.

[0365] Rotational viscosity was determined using the rotating permanent magnet method, and flow viscosity was determined in a modified Ubbelohde viscometer. For liquid crystal mixtures ZLI-2293, ZLI-4792, and MLC-6608, all products sourced from Merck KGaA, Darmstadt, Germany, rotational viscosities (ν) measured at 20°C were 161 mPa·s, 133 mPa·s, and 186 mPa·s, respectively, and flow viscosity (ν) was 21 mm·s, respectively. 2 ·s -1 14mm 2 ·s -1 and 27mm 2 ·s -1 .

[0366] Use the following symbols unless otherwise explicitly stated:

[0367] V0 Threshold voltage, capacitive, [V] at 20°C

[0368] n e Unusual optical refractive index measured at 20°C and 589 nm

[0369] n o Ordinary optical refractive index measured at 20℃ and 589nm.

[0370] Optical anisotropy of Δn measured at 20℃ and 589nm.

[0371] ε ⊥ Dielectric polarization perpendicular to the director at 20℃ and 1kHz

[0372] ε || Dielectric polarizability parallel to the director at 20℃ and 1kHz

[0373] Dielectric anisotropy of Δε at 20℃ and 1kHz

[0374] cl.p. or

[0375] T(N,I) Clear the light [°C],

[0376] ν Flow viscosity measured at 20℃ [mm 2 ·s -1 ],

[0377] The rotational viscosity [mPa·s] of γ1 measured at 20℃.

[0378] K1 is the elastic constant, and the "oblique expansion" deformation at 20℃ [pN].

[0379] K2 is the elastic constant, and the "torsional" deformation at 20°C [pN].

[0380] K3 is the elastic constant, the bending deformation at 20°C [pN], and

[0381] The low-temperature stability of the LTS phase was determined in a test kit.

[0382] VHR (Voltage Hold-up)

[0383] ΔVHR is the decrease in the voltage holding ratio.

[0384] S rel The relative stability of VHR.

[0385] The following examples are intended to explain the invention and not to limit it. However, these examples, using preferred compounds and their respective concentrations and combinations thereof, demonstrate to those skilled in the art the conception of preferred mixtures. Furthermore, the examples illustrate the available properties and combinations thereof.

[0386] For the purposes of this invention and in the embodiments described below, the structures of the liquid crystal compounds are described using acronyms, wherein chemical formula conversions are performed according to Tables A to C below. All groups C n H 2n+1 C m H 2m+1 and C lH 21+1 Or C n H 2n C m H 2m and C l H 2l The compounds are straight-chain alkyl or alkylene groups, having n, m, and l carbon atoms in each case. Table A shows the coding of the ring elements of the compound core, Table B lists the bridging units, and Table C lists the symbol meanings of the left-hand and right-hand end groups of the molecule. Acronyms consist of the coding of the ring element with an optional linking group, followed by the coding of the first hyphen and the left-hand end group, and the coding of the second hyphen and the right-hand end group. Table D shows the descriptive structures of the compounds and their respective abbreviations.

[0387] Table A: Ring Elements

[0388]

[0389]

[0390] Table B: Bridged Elements

[0391]

[0392] Table C: End bases

[0393]

[0394] Where n and m are integers, and the three dots “…” are placeholders for other abbreviations in this table.

[0395] In addition to the compound of formula I, the mixture according to the invention preferably also contains one or more of the compounds listed below.

[0396] Use the following abbreviations:

[0397] (n, m, and l are each independent integers, preferably 1 to 6)

[0398] Table D

[0399]

[0400]

[0401]

[0402]

[0403]

[0404]

[0405]

[0406] Table E shows the chiral dopants preferred for use in mixtures according to the invention.

[0407] Table E

[0408]

[0409]

[0410]

[0411] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds selected from the compounds in Table E.

[0412] Table F shows stabilizers, other than compounds of formula I, that are preferably used in mixtures according to the invention. Here, the parameter n represents an integer from 1 to 12. In particular, the phenolic derivatives shown can be used as other stabilizers because they act as antioxidants.

[0413] Table F

[0414]

[0415]

[0416]

[0417]

[0418] In a preferred embodiment of the invention, the medium according to the invention comprises one or more compounds selected from the compounds in Table F, particularly one or more compounds selected from the following two formulas.

[0419] Detailed Implementation Plan

[0420] The present invention also relates to the following embodiments:

[0421] 1. Liquid crystal medium, comprising,

[0422] c) One or more compounds of formula I

[0423]

[0424] in

[0425] n represents 1, 2, 3, or 4.

[0426] m represents (4-n),

[0427] This indicates an organic group with four bonding sites.

[0428] Z 11 and Z 12 Independently represented by -O-, -(C=O)-, -(NR-). 14 - or a single bond, but not simultaneously representing -O-.

[0429] r and s, independently representing 0 or 1,

[0430] Y 11 To Y 14 Each independently represents an alkyl group having 1-4 carbon atoms, and optionally, also independently, group pairs (Y 11 and Y 12 ) and (Y 13 and Y 14 One or two of them together represent a divalent group having 3-6 carbon atoms.

[0431] R 11 OR 13 O ● Or OH, preferably OR 13 Or O ● O is the preferred choice ● OH, isopropoxy, cyclohexyloxy, acetylphenoxy, phenoxy, and very particularly preferred OH,

[0432] R 12 Each occurrence independently represents H, F, and OR. 14 NR 14 R 15 A straight-chain or branched alkyl chain having 1-20 carbon atoms, wherein one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-, or representing a hydrocarbon group containing a cycloalkyl or alkylcycloalkyl unit, wherein one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-, and one or more H atoms can be replaced by OR 14 、N(R 14 (R) 15 ) or R 16 Substitution, or representing an aromatic or heteroaromatic hydrocarbon group, wherein one or more H atoms can be ORed. 14 、N(R14 (R) 15 ) or R 16 Replacement

[0433] R 13 Each time it appears, it independently represents a straight-chain or branched alkyl chain having 1-20 C atoms, where one or more -CH2- groups can be substituted with -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted with -O-. Alternatively, it represents a hydrocarbon group containing a cycloalkyl or alkylcycloalkyl unit, where one or more -CH2- groups can be substituted with -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted with -O-, and one or more H atoms can be substituted with OR. 14 、N(R 14 (R) 15 ) or R 16 Substitution, or representing an aromatic or heteroaromatic hydrocarbon group, wherein one or more H atoms can be ORed. 14 、N(R 14 (R) 15 ) or R 16 Replacement

[0434] Or it could be (1,4-cyclohexylene), wherein one or more -CH2- groups can be -O-, -CO- or -NR. 14 -Alternatives, or can be acetylated, isopropyl, or 3-heptyl.

[0435] R 14 Each time they appear independently, they represent a straight-chain or branched alkyl or acyl group having 1-10 carbon atoms, or an aromatic hydrocarbon or carboxyl group having 6-12 carbon atoms.

[0436] R 15 Each time they appear independently, they represent a straight-chain or branched alkyl or acyl group having 1-10 carbon atoms, or an aromatic hydrocarbon or carboxyl group having 6-12 carbon atoms.

[0437] R 16 Each occurrence of these terms is independent of the others, representing a straight-chain or branched alkyl group having 1-10 carbon atoms. One or more -CH2- groups may be substituted by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted by -O-.

[0438] The prerequisite is that,

[0439] When n=1, R 11 =O ● And -[Z11 ] r -[Z 12 ] s -=-O-, -(CO)-O-, -O-(CO)-, -O-(CO)-O-, -NR 14 -or-NR 14 In the case of -(CO)-,

[0440]

[0441] Not indicating

[0442] Straight-chain or branched alkyl groups having 1-10 carbon atoms, as well as cycloalkyl, cycloalkylalkyl, or alkylcycloalkyl groups, wherein in all these groups, one or more -CH2- groups can be replaced by -O- in such a way that the two O atoms are not directly bonded to each other in the molecule.

[0443] The following compounds are excluded from Formula I.

[0444]

[0445] as well as

[0446] In n=2 and R 11 =OR 13 In the case of R 13 Does not mean nC 1-9 -alkyl, and

[0447] d) One or more compounds of formula III-O

[0448]

[0449] in

[0450] R 31 This refers to unsubstituted alkyl groups having 1-7 carbon atoms.

[0451] R 32 This refers to an unsubstituted alkyl group having 1-7 carbon atoms, an unsubstituted alkoxy group having 1-6 carbon atoms, or an unsubstituted olefinic group having 2-6 carbon atoms, and...

[0452] i represents 0 or 1.

[0453] 2. The medium according to embodiment 1, characterized in that it comprises one or more compounds of formula I selected from compounds of formula I-1 to I-9.

[0454]

[0455]

[0456] The parameters have the meanings shown in Implementation Scheme 1, and

[0457] t represents an integer from 1 to 12.

[0458] R 17 This indicates a straight-chain or branched alkyl chain with 1-12 carbon atoms, where one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-. Alternatively, it can indicate an aromatic or heteroaromatic hydrocarbon group, where one or more H atoms can be replaced by OR. 14 、N(R 14 (R) 15 ) or R 16 Replacement.

[0459] 3. The medium according to embodiment 1 or 2, characterized in that it comprises one or more compounds of formula I selected from compounds of formula I-1a-1 to I-8a-1.

[0460]

[0461]

[0462]

[0463]

[0464] 4. A liquid crystal medium according to at least one of embodiments 1-3, characterized in that it further comprises

[0465] c) One or more compounds of formula II,

[0466]

[0467] in

[0468] R 21 This indicates an unsubstituted alkyl group having 1-7 carbon atoms or an unsubstituted alkenyl group having 2-7 carbon atoms, and

[0469] R 22 Unsubstituted alkenyl groups with 2-7 carbon atoms

[0470] and / or

[0471] d) One or more compounds selected from formulas III-1 to III-4

[0472]

[0473] in

[0474] R31 This refers to unsubstituted alkyl groups having 1-7 carbon atoms.

[0475] R 32 This indicates an unsubstituted alkyl group having 1-7 carbon atoms or an unsubstituted alkoxy group having 1-6 carbon atoms, and

[0476] m, n, and o each represent 0 or 1 independently.

[0477] 5. A medium according to at least one of embodiments 1-4, characterized in that the total concentration of the compound of formula I in the entire medium is 1 ppm or higher up to 1000 ppm or lower.

[0478] 6. A medium according to at least one of embodiments 1-5, characterized in that it comprises a compound of formula II, as shown in embodiment 4, wherein R 21 Represents n-propyl and R 22 It indicates vinyl.

[0479] 7. A medium according to at least one of embodiments 1-6, characterized in that the total concentration of the compound of formula III-O in the entire medium is 5% or higher up to 40% or lower.

[0480] 8. A medium according to at least one of embodiments 1-7, characterized in that it comprises one or more compounds of formula III-O-1.

[0481]

[0482] Where R 31 and R 32 Each has its own meaning as given in Implementation Scheme 1 for Formula III-O.

[0483] 9. A medium according to at least one of embodiments 1-8, characterized in that it comprises one or more compounds of formula III-O-2.

[0484]

[0485] Where R 31 and R 32 Each has its own meaning as given in Implementation Scheme 1 for Formula III-O.

[0486] 10. A medium according to at least one of embodiments 1-9, characterized in that it further comprises one or more chiral compounds.

[0487] 11. An electro-optic display or electro-optic component, characterized in that it comprises a liquid crystal medium according to at least one of embodiments 1-10.

[0488] 12. The display according to embodiment 11 is characterized in that it is based on the VA or ECB effect.

[0489] 13. The display according to embodiment 11 or 12, characterized in that it includes an active matrix addressing device.

[0490] 14. Use of a medium according to at least one of embodiments 1-10 in an electro-optic display or electro-optic assembly.

[0491] 15. A method for preparing a liquid crystal medium according to at least one of embodiments 1-10, characterized in that one or more compounds of formula I are mixed with one or more compounds of formula III-O and / or one or more compounds of formula II and / or one or more compounds selected from formula III-1 to III-4.

[0492] 16. The method for stabilizing a liquid crystal medium according to embodiment 15, characterized in that the medium comprises one or more compounds of formula III-O, one or more compounds of formula I, and optionally one or more compounds selected from formulas OH-1 to OH-6 are added to the medium:

[0493]

[0494] Example

[0495] The following embodiments are used to explain the invention and not to limit it in any way. However, the physical properties described will make it clear to those skilled in the art what properties can be achieved and within what range such properties can be varied. In particular, the various combinations of properties that can be preferably achieved are thus well defined to those skilled in the art.

[0496] Material Examples

[0497] The following substances are preferred substances according to Formula I of this application or substances of Formula I preferred for use according to this application.

[0498]

[0499]

[0500]

[0501]

[0502]

[0503]

[0504]

[0505]

[0506]

[0507] Synthetic Example 1: Bis(2,2,6,6-tetramethyl-4-piperidinyl)-N,N'-dioxysuccinate (Material Example) Synthesis of Example 1)

[0508]

[0509] First, 2.15 g (12.26 mmol) of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy, 40 mg (0.33 mmol) of 4-(dimethylamino)pyridine, and 1 ml (12.4 mmol) of dry pyridine were added to 20 ml of dry dichloromethane. Then, 4 Å of activated molecular sieve was added, and the mixture was stirred at room temperature (RT; approximately 22 °C) for 90 minutes. The reaction solution was cooled to a temperature range of 7 to 10 °C, and 0.71 ml (6.13 mmol) of succinyl dichloride was slowly added, while the mixture was stirred at RT for 18 hours. Sufficient saturated NaHCO3 solution and dichloromethane were added to the reaction solution, and the organic phase was separated, washed with water and saturated NaCl solution, dried over Na2SO4, filtered, and evaporated. The crude product was purified on silica gel using dichloromethane / methyl tert-butyl ether (95:5) to give a white solid product with a purity >99.5%.

[0510] Synthetic Example 2: Bis(2,2,6,6-Tetramethylpiperidin-1-oxy-4-yl) sebacate (Substance Example 4) synthesis

[0511]

[0512] 28.5 g (166 mmol) of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy (free radical) and 250 mg (2.05 mmol) of 4-(dimethylamino)pyridine were dissolved in 300 mL of degassed dichloromethane, and 50.0 mL (361 mmol) of triethylamine were added. The mixture was then degassed and cooled to 0 °C. 10 g (41.4 mmol) of sebacate chloride dissolved in 100 mL of degassed dichloromethane was added dropwise at 0–5 °C, and the mixture was stirred at room temperature for 18 hours. After the reaction was complete, water and HCl (pH 4–5) were added under ice-cold conditions, and the mixture was stirred for another 30 minutes. The organic phase was separated, and the aqueous phase was subsequently extracted with dichloromethane. The combined organic phases were washed with saturated NaCl solution and dried with Na2SO4. The mixture was filtered and evaporated to give 24.4 g of a red liquid. This liquid was then passed through a glass filter with 100 g of basic Al2O3 and 500 g of silica gel along with dichloromethane / methyl tert-butyl ether (95 / 5) to give orange crystals. These crystals were dissolved in degassed acetonitrile at 50 °C and crystallized at -25 °C to give an orange crystalline product with 99.9% HPLC purity.

[0513] Synthesis Example 3: Bis(2,2,6,6-Tetramethyl-4-piperidinyl)-N,N'-dioxybutanediol (Material Example) 7) Synthesis

[0514]

[0515] Under a protective atmosphere, sufficient pentane was added to 15.0 g (60% in mineral oil, 375 mmol) of NaH, and the mixture was allowed to stand. The pentane supernatant was aspirated and carefully quenched with isopropanol under cooling conditions. Then, 100 mL of THF was carefully added to the washed NaH. The reaction mixture was heated to 55 °C, and 50.0 g (284 mmol) of a solution of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy in 400 mL of THF was carefully added dropwise. The generated hydrogen gas was released directly. When the solution addition was complete, stirring was continued at 60 °C overnight (16 h). The reaction mixture was then cooled to 5 °C, and 1,4-butanediol dimethylsulfonate was added fractionally. The mixture was then slowly heated to 60 °C and stirred at this temperature for 16 h. When the reaction was complete, the mixture was cooled to RT, and 200 mL of 6% ammonia solution was added under cooling conditions, and the mixture was stirred for 1 h. The organic phase was then separated, the aqueous phase was washed with methyl tert-butyl ether, the combined organic phases were washed with saturated NaCl solution, dried, and evaporated. The crude product was purified on silica gel with dichloromethane / methyl tert-butyl ether (8:2) and crystallized from acetonitrile at -20 °C to give a pink crystalline solid product with a purity of >99.5%.

[0516] Synthetic Example 4: Bis[2,2,6,6-Tetramethyl-1-(1-phenylethoxy)piperidin-4-yl]succinate (substance) Synthesis of Example 24)

[0517]

[0518] Step 4.1: Synthesis of 2,2,6,6-Tetramethyl-1-(1-phenylethoxy)piperidine-4-ol

[0519]

[0520] First, 5.0 g (29.03 mmol) of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy, 7.80 g (58.1 mmol) of 2-phenylpropanal, and 100.6 mg (1.02 mmol) of copper chloride (I) were added to 20 mL of tert-butanol. Then, 6.45 mL (58.06 mmol) of 35% hydrogen peroxide solution was carefully and slowly added dropwise at a rate that kept the internal temperature below 30 °C. Therefore, the mixture was cooled under ice-cold conditions during the addition. Oxygen is formed in the reaction and will be spontaneously released in large quantities if added too quickly and at too high a temperature. When the addition was complete, the reaction solution was stirred at RT for an additional 16 hours, followed by the addition of sufficient water / methyl tert-butyl ether, and the organic phase was separated. The organic phase was washed with 10% ascorbic acid until no peroxides were found and the peroxide content was checked. The mixture was then washed with 10% NaOH solution, water, and saturated NaCl solution, dried with Na2SO4, filtered, and evaporated. The crude product was purified on silica gel with heptane / methyl tert-butyl ether (1:1) to give a colorless crystalline product.

[0521] Step 4.2: Synthesis of [2,2,6,6-tetramethyl-1-(1-phenylethoxy)piperidin-4-yl]succinate

[0522] First, 1.52 g (5.5 mmol) of the product from the previous step, compound 2,2,6,6-tetramethyl-1-(1-phenylethoxy)piperidin-4-ol, 15.3 mg (0.125 mmol) of dimethylaminopyridine, and 1.02 mL (12.6 mmol) of dry pyridine were added to 10 mL of dichloromethane and cooled to a temperature range of 7–10 °C. Then, 0.255 mL (2.199 mmol) of succinyl dichloride was added dropwise as is, and if necessary, the hydroxyl compounds were still present. When the reaction was complete, the reaction mixture was filtered directly through silica gel with dichloromethane and then eluted with heptane / methyl tert-butyl ether (1:1) and pure methyl tert-butyl ether. The resulting product was dissolved in acetonitrile and purified by a pre-prepared HPLC system (two Chromolith columns, using acetonitrile at 50 mL / min) to give a yellow oil product with a purity >99.9%.

[0523] Synthetic Example 5: 2,2,6,6-Tetramethyl-1-(1-phenylethoxy)piperidin-4-yl]valerate (substance example) Synthesis of Example 31)

[0524]

[0525] 2.5 g (9.01 mmol) of compound 2,2,6,6-tetramethyl-1-(1-phenylethoxy)piperidin-4-ol from step 3.1 and 55.1 mg (0.45 mmol) of (4-dimethylaminopyridine) were dissolved in 50.0 mL of dry dichloromethane and cooled to 3 °C. At this temperature, 5.47 mL (27.03 mmol) of valeric anhydride was added, and the mixture was stirred at room temperature for 14 hours. When the reaction was complete, the mixture was carefully poured into ice water, adjusted to pH 6 with 2N HCl, and the organic phase was separated. The aqueous phase was extracted with dichloromethane and the combined organic phases were washed with a mixture of saturated NaCl solution, water, and triethylamine (300:50 mL), dried over MgSO4, filtered, and evaporated. The product was purified on silica gel with heptane / methyl tert-butyl ether (9:1) to give a colorless oil.

[0526] Synthetic Example 6: 1,4-bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl)succinate (Material Example) Synthesis of 49)

[0527]

[0528] 40 ml of water and 80 ml of dioxane were mixed and carefully degassed using an argon stream. 2.0 g (4.7 mmol) of the free radical from Material Example 1 (Synthetic Example 1) was dissolved in the solvent mixture, and 4.95 g (28.1 mmol) of ascorbic acid was added fractionally. The reaction mixture became colorless during the addition and was stirred at 40 °C for 18 hours under a protective atmosphere. The mixture was cooled to room temperature, and 100 ml of water was added. The mixture was briefly stirred and the resulting crystals were filtered. The crystals were dissolved in 50 ml of hot, degassed THF, and the insoluble components were filtered off. The filtrate was allowed to crystallize at -25 °C. The light pink crystals were then washed with acetonitrile at room temperature for 18 hours to obtain a light pink crystalline product of 100% HPLC purity.

[0529] Synthetic Example 7: 1,10-bis(1-hydroxy-2,2,6,6-tetramethyl-4-piperidinyl) sebacate (substance example) Synthesis of Example 50)

[0530]

[0531] All solvents used were thoroughly degassed beforehand by an argon stream. An amber glass apparatus must be used during the process. 1.70 g (3.32 mmol) of the free radical from Material Example 4 (Synthetic Example 2) was dissolved in 60 mL of dioxane. Then, 3.6 g (20 mmol) of ascorbic acid dissolved in 30 mL of water was added dropwise to the solution at room temperature. The reaction solution began to turn colorless during the addition and the reaction was complete after stirring at room temperature for 1 hour. The mixture was extracted with 100 mL of dichloromethane, and the organic phase was washed with water, dried with Na₂SO₄, filtered, and evaporated. The resulting yellow crystals were obtained at 160 °C and 10 °C.-2 Drying at mbar for 5 minutes yields a viscous, slowly crystallizing oil.

[0532] Liquid crystal mixtures with the compositions and properties shown in the table below were prepared and studied.

[0533] Examples 1.1 to 1.3 and Comparative Example 1

[0534] The following mixture (M-1) was prepared and studied, which contained a total of slightly more than 20% of a CH2O-bridged compound of formula III-O.

[0535]

[0536] Note: tbd: to be determined.

[0537] The mixture M-1 was divided into five portions, and the following study was conducted.

[0538] Comparative Example 1

[0539] First, the stability of the voltage retention rate of the mixture (M-1) itself was determined. The stability of the mixture M-1 itself to illumination was studied by means of cold cathode ((CCFL)-LCD backlight) illumination in a test chamber with alignment materials for vertical alignment and planar ITO electrodes. For this purpose, the corresponding test chamber was exposed to illumination conditions for 1056 hours. Then, the voltage retention rate was measured after 5 minutes at 100°C under different conditions. The results are summarized in Table 1 below. Here, as described below, for each individual mixture, six test chambers were filled and studied. The values ​​shown are the average of the six individual values ​​and their standard deviation (σ), including cases where the standard deviation is less than the accuracy of the above measurements.

[0540] Examples 1.1 to 1.3:

[0541] Then, optionally, 250 ppm of the compound of Example 1 (i.e., Material Example 1) was synthesized.

[0542]

[0543] Alternatively, synthesize the compound of Example 2 (i.e., Material Example 4) at 250 ppm.

[0544]

[0545] Alternatively, synthesize the compound of Example 7 (i.e., Material Example 50) at 250 ppm.

[0546]

[0547] Add to mixture M-1. The stability of the resulting mixtures (M-1-1 to M-1-3) was studied according to the method described above. The results are shown in Table 1 below.

[0548] In different measurement series, the relative deviation of the “voltage retention rate value” is usually in the range of at most about 2%, and in exceptional cases it can be at a maximum of about 3 to 4%.

[0549] The reduction in voltage retention rate (ΔVHR) caused by exposure is usually measured as described above.

[0550] Table 1

[0551]

[0552] Note: I(1)*: Compound from Synthesis Example 1

[0553] I(2)*: Compound synthesized in Example 2

[0554] I(3)*: Synthetic compound of Example 7

[0555] tbd: To be determined

[0556] It is evident here that the compound of Synthetic Example 1 exhibits significantly stabilizing properties. The starting mixture without a stabilizer shows a considerable decrease in VHR after backlight exposure and is therefore unsuitable for most modern LCD applications. The mixture according to the invention, containing compound of formula I, shows a VHR value after exposure that is not only superior to that of the starting mixture but also superior to that of the mixture of the comparative examples.

[0557] All the stabilizers used significantly improved the VHR value before backlight exposure. The unstabilized reference showed a significant decrease in VHR after backlight exposure. The stabilizers used almost completely prevented this phenomenon. The best results were obtained using I(1). The use of the compounds shown, especially those of formula I, also makes the studied mixtures suitable for modern, demanding LCD applications.

[0558] The compound from Synthetic Example 1, at a concentration of 250 ppm, exhibited superior stabilizing activity compared to all other stabilizers studied herein. This resulted in a reduced probability of image delay occurring after backlighting.

[0559] Example 2 (Examples 2.1 to 2.3 and Comparative Example 2)

[0560] The following mixture (M-2) was prepared and studied, which contained a total of 13.5% of two CH2O-bridged compounds of formula III-O-2.

[0561]

[0562] The mixture M-2 was divided into four portions as described in Example 1, and processed and subjected to the studies described therein. The results are shown in the table below.

[0563] Table 2

[0564]

[0565] Note: I(1)*: Compound from Synthesis Example 1

[0566] I(2)*: Compound synthesized in Example 2

[0567] I(3)*: Synthetic compound of Example 7

[0568] All compounds of Formula I used here significantly improve the stability of the mixtures used. In particular, this applies to the values ​​after exposure testing. (The values ​​before exposure testing are almost indistinguishable within the range of measurement accuracy). Even at a concentration of only 100 ppm, stabilizer I (2) exhibits particularly high activity here and a high VHR after backlighting. Mixture M-2 is used only to a limited extent in LCDs without the use of stabilizers. The use of compounds of Formula I results in an increase in VHR to a value that is usable in most corresponding LCDs.

[0569] Even at a concentration of 100 ppm, the compounds of Synthetic Example 2, and those of Synthetic Example 7 at a concentration of 250 ppm, exhibited superior stabilizing activity relative to all other stabilizers studied herein. Even at a concentration of only 100 ppm, the compounds of Synthetic Example 1 yielded very good results. Here, for compounds I(2) and I(3), or considering the respective concentrations used, the best absolute effect was observed for compound I(2).

[0570] Example 3 (Examples 3.1 to 3.3 and Comparative Example 3)

[0571] The following mixture (M-3) was prepared and studied, which contained a total of 11% of a CH2O-bridged compound of formula III-O-1.

[0572]

[0573] The mixture M-3 was divided into four portions as described in Example 1, and the processes and studies described therein were performed. The results are shown in the table below.

[0574] Table 3

[0575]

[0576] Note: I(1)*: Compound from Synthesis Example 1

[0577] I(2)*: Compound synthesized in Example 2

[0578] I(3)*: Synthetic compound of Example 7

[0579] Compared to mixture M-2 in Example 2, mixture M-3 itself has a slightly higher VHR, both before and after exposure.

[0580] As in Example 2, all compounds of Formula I used here also exhibit improved VHR after exposure. Here, stabilizer I (3) shows particularly high activity after backlight exposure. Mixture M-3 is used only to a limited extent in LCDs without the use of stabilizers. The use of the stabilizers, especially the compounds of Formula I, results in an increase in VHR to a value that can be used in most corresponding LCDs.

[0581] Similarly, as described in Example 2, even at a concentration of 100 ppm, the compounds of Synthetic Examples 1 and 2, and the compound of Synthetic Example 7 at a concentration of 250 ppm, exhibited superior stabilizing activity relative to all other stabilizers studied herein. The best effect was observed with compound I(3) of Synthetic Example 7 used at a concentration of 250 ppm.

Claims

1. Liquid crystal medium, comprising, a) One or more compounds of formula I in n represents 2, 3, or 4. m represents (4-n), represents an organic group having 4 bonding sites, Z 11 and Z 12 , independently of one another, denote -O-, -(C=0)-, -(N-R 14 )- or a single bond, but not simultaneously -O-, r and s, independently representing 0 or 1, Y 11 to Y 14 each, independently of one another, denote alkyl having 1-4 C atoms, and, alternatively, also, independently of one another, the pair of radicals (Y 11 and Y 12 ) and (Y 13 and Y 14 ) together denote a divalent radical having 3-6 C atoms, R 11 represents O ● , R 12 Each occurrence independently represents H, F, and OR. 14 NR 14 R 15 A straight-chain or branched alkyl chain having 1-20 carbon atoms, wherein one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-, or representing a hydrocarbon group containing a cycloalkyl or alkylcycloalkyl unit, wherein one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-, and one or more H atoms can be replaced by OR 14 、N(R 14 (R) 15 ) or R 16 Substitution, or representing an aromatic or heteroaromatic hydrocarbon group, wherein one or more H atoms can be ORed. 14 、N(R 14 (R) 15 ) or R 16 Replacement R 14 independently of one another on each occurrence, denotes a straight-chain or branched alkyl or acyl radical having 1 -10 C atoms, or an aromatic hydrocarbon radical or carboxyl radical having 6-12 C atoms, R 15 independently of one another on each occurrence, denotes a straight-chain or branched alkyl or acyl radical having 1 -10 C atoms, or an aromatic hydrocarbon radical or carboxyl radical having 6-12 C atoms, R 16 Each occurrence of these terms is independent of the others, representing a straight-chain or branched alkyl group having 1-10 carbon atoms. One or more -CH2- groups may be substituted by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be substituted by -O-. The following compounds are excluded from Formula I. as well as b) One or more compounds of formula III-O in R 31 represents unsubstituted alkyl having 1-7 C atoms, R 32 denotes unsubstituted alkyl having 1 -7 C atoms or unsubstituted alkoxy having 1 -6 C atoms, or unsubstituted alkenyloxy having 2-6 C atoms, and i represents 0 or 1, The liquid crystal medium comprises one or more compounds of formula IV-1. in alkyl and alkyl', independently of each other, represent alkyl groups having 1-7 carbon atoms.

2. The medium according to claim 1, characterized in that it comprises one or more compounds of formula I selected from compounds of formula I-1 to I-9. wherein, The parameters have the meaning shown in claim 1, and t represents an integer from 1 to 12. R 17 This indicates a straight-chain or branched alkyl chain with 1-12 carbon atoms, where one or more -CH2- groups can be replaced by -O- or -C(=O)-, but two adjacent -CH2- groups cannot be replaced by -O-. Alternatively, it can indicate an aromatic or heteroaromatic hydrocarbon group, where one or more H atoms can be replaced by OR. 14 、N(R 14 (R) 15 ) or R 16 Replacement.

3. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds of formula I selected from compounds of formula I-1a-1 to I-8a-1.

4. The liquid crystal medium according to claim 1 or 2, characterized in that it further comprises c) One or more compounds of formula II, in R 21 denotes unsubstituted alkyl having 1-7 C atoms or unsubstituted alkenyl having 2-7 C atoms, and R 22 R represents unsubstituted alkyl having 1-7 C atoms, and / or d) One or more compounds selected from formulas III-1 to III-4 in R 31 represents unsubstituted alkyl having 1-7 C atoms, R 32 denotes unsubstituted alkyl having 1-7 C atoms or unsubstituted alkoxy having 1-6 C atoms, and m, n, and o each represent 0 or 1 independently.

5. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds selected from formulas I-1a-1 to I-2a-2.

6. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds selected from formulas I-1a-1 to I-1a-5.

7. The medium according to claim 1 or 2, characterized in that it comprises a compound of formula I-1a-1.

8. The medium according to claim 1 or 2, characterized in that it comprises a compound of formula I-1a-5.

9. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds of formula I, wherein n represents 3.

10. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds of formula I, wherein n represents 4.

11. The medium according to claim 1 or 2, characterized in that the total concentration of the compound of formula I in the entire medium is 1 ppm or higher up to 1000 ppm or lower.

12. Medium according to claim 1 or 2, characterized in that it comprises a compound of formula II as indicated in claim 4, wherein R 21 represents n-propyl and R 22 represents vinyl.

13. The medium according to claim 1 or 2, characterized in that the total concentration of the compound of formula III-O in the entire medium is 5% or higher up to 40% or lower.

14. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds of formula III-O-1. wherein R 31 and R 32 have the respective meanings given for formula III-O according to claim 1.

15. The medium according to claim 1 or 2, characterized in that it comprises one or more compounds of formula III-O-2. wherein R 31 and R 32 have the respective meanings given in claim 1 for formula III-O.

16. The medium according to claim 1 or 2, characterized in that it further comprises one or more chiral compounds.

17. An electro-optic display or electro-optic assembly, characterized in that it comprises a liquid crystal medium according to any one of claims 1-16.

18. The display according to claim 17, characterized in that it is based on the VA or ECB effect.

19. The display according to claim 17 or 18, characterized in that it comprises an active matrix addressing device.

20. Use of the liquid crystal medium according to any one of claims 1-16 in an electro-optic display or electro-optic assembly.

21. A method for preparing a liquid crystal medium according to claim 16, characterized in that one or more compounds of formula I are mixed with one or more compounds of formula IV-1, one or more compounds of formula III-O and / or one or more compounds of formula II and / or one or more compounds selected from formulas III-1 to III-4.

22. The method for stabilizing the liquid crystal medium prepared according to claim 21, characterized in that the medium comprises one or more compounds of formula III-O, one or more compounds of formula I, and optionally one or more compounds selected from formulas OH-1 to OH-6 are added to the medium:

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