TWI757429B - Liquid-crystalline medium - Google Patents

Abstract

The present invention relates to a liquid-crystalline medium (LC medium) which comprises at least one compound of the formula I,

Description

liquid crystal medium

其中X為O或S且另一變數具有技術方案1中所表示之含義； 及作為用於穩定之添加劑的指定可聚合哌啶衍生物；係關於一種用途，其用於電光目的；以及係關於LC顯示器，其含有此介質，特定而言係關於利用介電負極液晶之使用IPS (共平面切換型)或FFS (邊緣場切換型)效應的液晶顯示器。The present invention relates to a liquid crystal medium (LC medium) comprising at least one compound of the formula I,

wherein X is O or S and the other variable has the meaning indicated in Scheme 1; and the designated polymerizable piperidine derivative as an additive for stabilization; relating to a use, which is used for electro-optical purposes; and relating to LC displays, which contain this medium, relate in particular to liquid crystal displays using IPS (In-Plane Switching) or FFS (Fringe Field Switching) effects using dielectric negative liquid crystals.

The principle of electrically controlled birefringence, the ECB effect or also the DAP (Deformation of Alignment Phase) effect was first described in 1971 (MF Schieckel and K. Fahrenschon, "Deformation of nematic liquid crystals with vertical orientation in electrical fields", Appl. Phys . Lett. 19 (1971), 3912). It is subsequently described in the paper by JF Kahn (Appl. Phys. Lett. 20 (1972), 1193) and in the paper by G. Labrunie and J. Robert (J. Appl. Phys. 44 (1973), 4869). 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) The paper shows that the liquid crystal phase must have high elastic constant K ₃ /K ₁ ratio, high optical anisotropy Δn value and dielectric anisotropy value De≤-0.5 in order to be suitable for high information display devices based on the ECB effect. Electro-optical display elements based on the ECB effect have vertical edge alignment (VA technology = vertically aligned). Dielectrically negative liquid crystal media can also be used in displays using the so-called IPS or FFS effect. Although FFS-type displays using a dielectric negative compound are commonly referred to as UB-FFS, IPS displays with a negative compound should be referred to herein as negative IPS (also sometimes U-IPS). Negative IPS displays have substantially the same electrode configuration as their IPS counterparts. However, the initial alignment of the liquid crystal director is not parallel to the electrodes in the off state, but is rectangular. The switching occurs by coplanar twisting of the director as in common IPS displays, resulting in an alignment that is nearly parallel to the electrodes. Except for in-plane switching (IPS) displays (eg Yeo, SD, Paper 15.3: "An LC Display for the TV Application", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Volume II, 758 and 759) and the already well-known twisted nematic (TN) displays, e.g. in multi-domain vertical alignment (MVA, 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, Volume I, pp. 6-9, and Liu, CT et al., Paper 15.1: " A 46-inch TFT-LCD HDTV Technology ...", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Vol. II, pp. 750-753), patterned vertical alignment (PVA) , eg: Kim, Sang Soo, Paper 15.4: "Super PVA Sets New State-of-the-Art for LCD-TV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, Volume II, pp. 760-pp. 763 pages), advanced super view (ASV, eg: Shigeta, Mitzuhiro and Fukuoka, Hirofumi, Paper 15.2: "Development of High Quality LCDTV", SID 2004 International Symposium, Digest of Technical Papers, XXXV, p. Volume II, pages 754 to 757) mode displays using the ECB effect, such as the so-called vertically aligned nematic type (ver tically aligned nematic; VAN) displays have established themselves as one of the three newer types of liquid crystal displays that are currently the most important, especially for television applications. Such techniques are described in general form in, for example, 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 for comparison. Although the response time of modern ECB displays has been significantly improved by addressing methods using overdrive overdrive, e.g. 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, Volume I, pp. 106 to 109, but the achievement of video-compatible response time, especially about grayscale conversion, is still an unsatisfactory problem. The industrial application of this effect in electro-optical display elements requires an LC phase that must meet various requirements. In this context, chemical resistance to moisture, air and physical influences such as heat, infrared, visible and ultraviolet radiation, and direct and alternating electric fields is particularly important. In addition, an industrially available LC phase is required to have a liquid crystal mesophase in a suitable temperature range and at a low viscosity. None of the series of compounds with liquid crystal mesophases disclosed so far includes a single compound that meets all of these requirements. Thus a mixture of two to 25, preferably three to 18, compounds is typically prepared to obtain material that can be used as the LC phase. However, it is not possible to easily prepare optimal phases in this way, since liquid crystal materials with significant negative dielectric anisotropy and sufficient long-term stability have so far not been obtained. Matrix liquid crystal displays (MLC displays) are known. Non-linear elements that can be used for the individual conversion of individual pixels are, for example, active elements (ie, transistors). The term "active matrix" is then used, where a distinction can be made between the following two types: 1. Metal-oxide-semiconductor (MOS) transistors on silicon wafers as substrates 2. Thin-film transistors (TFTs) on glass plates as a substrate. A distinction is made between two technologies: based on polycrystalline and especially amorphous silicon, TFTs contain compound semiconductors, such as CdSe, or TFTs. The latter technique is widely used all over the world. A TFT matrix is applied to the inside of one glass plate of the display, while the other glass plate carries a transparent counter electrode inside it. Compared to the size of the pixel electrode, the TFT is extremely small and has little adverse effect on the image. This technique can also be extended to a fully colour-capable display in which a mosaic of red, green and blue light filters is arranged with filter elements opposing each switchable pixel. The term MLC display herein covers any matrix display with integrated nonlinear elements, ie in addition to an active matrix, the display also has passive elements, such as varistors or diodes (MIM=metal-insulator-metal). This type of MLC display is especially suitable for TV applications (eg portable TV) or high information displays in automobile or aircraft construction. In addition to the issues regarding the angular dependence of contrast and response time, difficulties arise in MLC displays due to the insufficiently high specific resistance of the liquid crystal mixture [TOGASHI, S., SEKIGUCHI, K., TANABE, H., YAMAMOTO, E. , SORIMACHI, K., TAJIMA, E., WATANABE, H., SHIMIZU, H., Proc. Eurodisplay 84, September 1984: A 210-288 Matrix LCD Controlled by Double Stage Diode Rings, pp. 141 and below, Paris; STROMER, M., Proc. Eurodisplay 84, September 1984: Design of Thin Film Transistors for Matrix Addressing of Television Liquid Crystal Displays, pp. 145 et seq., Paris]. As the resistance decreases, the contrast ratio of the MLC display deteriorates. High (initial) resistance is extremely important for displays that must have acceptable resistance values over long periods of operation, as the specific resistance of liquid crystal mixtures typically declines with the life of an MLC display due to interaction with the inner surface of the display. There is still a great need for MLC displays with extremely high specific resistances while having large operating temperature ranges, short response times, and low threshold voltages, by means of which various grayscales can be produced. The disadvantages of commonly used MLC-TN displays are due to their relatively low contrast ratio, relatively high viewing angle dependence, and difficulty in producing grayscales in these displays.

其中 R¹ 及R^1* 各自彼此獨立地表示H、具有1至15個C原子之烷基或烷氧基，其中，另外，此等基團中之一或多個CH₂ 基團可各自彼此獨立地以O原子彼此不直接連接之方式由以下置換：-C≡C-、-CF₂ O-、-OCF₂ -、-CH=CH-、

、

、-O-、-CO-O-、-O-CO-，且其中另外，一或多個H原子可經鹵素置換， A¹ 及 A¹ * 各自彼此獨立地表示 a) 1,4-伸環己烯基或1,4-伸環己基，其中一或兩個不相鄰CH₂ 基團可由-O-或-S-置換， b) 1,4-伸苯基，其中一或兩個CH基團可由N置換， c) 來自哌啶-1,4-二基、1,4-雙環[2.2.2]伸辛基、萘-2,6-二基、十氫萘-2,6-二基、1,2,3,4-四氫萘-2,6-二基、菲-2,7-二基及茀-2,7-二基之基團， 其中基團a)、b)及c)可經鹵素原子單取代或多取代， Z¹ 及Z¹ * 各自彼此獨立地表示-CO-O-、-O-CO-、-CF₂ O-、-OCF₂ -、-CH₂ O-、-OCH₂ -、-CH₂ -、-CH₂ CH₂ -、-(CH₂ )₄ -、-CH=CH-CH₂ O-、-C₂ F₄ -、-CH₂ CF₂ -、-CF₂ CH₂ -、-CF=CF-、-CH=CF-、-CF=CH-、-CH=CH-、-C≡C-或單鍵， a、b 獨立為0或1， X 表示-S-或-O-，及 L¹ 及L² 各自彼此獨立地表示F、Cl、CF₃ 或CHF₂ ， 及如下至少一種式ST化合物，或包含其聚合形式之聚合物， P-Sp-(A² -Z² -A¹ )_m1 -Z¹ -Pip ST 其中個別基團彼此獨立地且在每次出現時相同或不同地具有以下含義： Pip 選自下式之基團

R^g H或具有1至10個C原子、較佳具有1至6個C原子、極佳具有1至4個C原子之直鏈或分支鏈烷基或烷氧基烷基，或苯甲基，最佳為H， R^a 、R^b 、R^c 、R^d 具有1至10個C原子、較佳具有1至6個C原子、極佳具有1至4個C原子之直鏈或分支鏈烷基， P 乙烯基氧基、丙烯酸酯基、甲基丙烯酸酯基、氟丙烯酸酯基、氯丙烯酸酯基、氧雜環丁烷基或環氧基，較佳地為丙烯酸酯基、甲基丙烯酸酯基、氟丙烯酸酯基、氯丙烯酸酯基，更佳地為丙烯酸酯基或甲基丙烯酸酯基，最佳為甲基丙烯酸酯基， Sp 間隔基團或單鍵， A¹ 、A² 具有4至30個環原子之脂環基、雜環基、芳族基或雜芳族基，其亦可含有稠環且視情況經一或多個基團L或R-(A³ -Z³ )_m2 -取代，且A¹ 及A² 中之一者亦可表示單鍵，A³ 具有4至30個環原子之脂環基、雜環基、芳族基或雜芳族基，其亦可含有稠環且視情況經一或多個基團L取代， Z¹ -O-、-S-、-CO-、-CO-O-、-O-CO-、-O-CO-O-、-OCH₂ -、-CH₂ O-、-SCH₂ -、-CH₂ S-、-CF₂ O-、-OCF₂ -、-CF₂ S-、-SCF₂ -、-(CH₂ )_n -、-CF₂ CH₂ -、-CH₂ CF₂ -、-(CF₂ )_n -、-CH=CH-、-CF=CF-、-CH=CF-、-CF=CH-、-C≡C-、-CH=CH-CO-O-、-O-CO-CH=CH-、-CH₂ -CH₂ -CO-O-、-O-CO-CH₂ -CH₂ -、-CR⁰⁰ R⁰⁰⁰ -或單鍵，其限制條件為，若m1為0，則Z¹ 為單鍵， Z² 、Z³ -O-、-S-、-CO-、-CO-O-、-O-CO-、-O-CO-O-、-OCH₂ -、-CH₂ O-、-SCH₂ -、-CH₂ S-、-CF₂ O-、-OCF₂ -、-CF₂ S-、-SCF₂ -、-(CH₂ )_n -、-CF₂ CH₂ -、-CH₂ CF₂ -、-(CF₂ )_n -、-CH=CH-、-CF=CF-、-CH=CF-、-CF=CH-、-C≡C-、-CH=CH-CO-O-、-O-CO-CH=CH-、-CH₂ -CH₂ -CO-O-、-O-CO-CH₂ -CH₂ -、-CR⁰⁰ R⁰⁰⁰ -或單鍵， R⁰⁰ 、R⁰⁰⁰ H或具有1至12個C原子之烷基， R P-Sp-、H、F、Cl、CN或具有1至25個C原子之直鏈、分支鏈烷基或環烷基，其中一或多個不相鄰CH₂ -基團視情況以O-及/或S-原子彼此不直接連接之方式經-O-、-S-、-CO-、-CO-O-、-O-CO-、-O-CO-O-置換，且其中一或多個H原子各自視情況經F、Cl或P-Sp-或基團Pip置換， L P-Sp-、F、Cl、CN、或具有1至25個C原子之直鏈、分支鏈烷基或環烷基，其中一或多個不相鄰CH₂ -基團視情況以O-及/或S-原子彼此不直接連接之方式經-O-、-S-、-CO-、-CO-O-、-O-CO-、-O-CO-O-置換，且其中一或多個H原子各自視情況經F、Cl或P-Sp-或選自式1、2及3之基團置換， m1 0、1、2、3或4， m2 0、1、2、3或4，及 n 1、2、3或4。 已經在WO 2016/116119 A1中提出式ST化合物作為可聚合液晶介質中之添加劑。 此類型介質可尤其用於基於ECB效應之具有主動矩陣定址之電光顯示器及IPS (共平面切換型)顯示器或FFS (邊緣場切換型)顯示器。The present invention relates to a liquid-crystalline medium comprising at least one compound of the formula I,

wherein R ¹ and R ^1* each independently of one another represent H, an alkyl group having from 1 to 15 C atoms or an alkoxy group, wherein, in addition, one or more CH ₂ groups of these groups can each independently of one another independently replaced by the following in such a way that the O atoms are not directly connected to each other: -C≡C-, -CF2O-, _-OCF2- , -CH= _CH- ,

,

, -O-, -CO-O-, -O-CO-, and wherein, in addition, one or more H atoms may be replaced by halogen, A ¹ and A ¹ * each independently of one another represent a) 1,4-extended Cyclohexenyl or 1,4-cyclohexylene, wherein one or two non-adjacent _CH2 groups can be replaced by -O- or -S-, b) 1,4-phenylene, wherein one or both The CH group can be replaced by N, c) from piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]denooctyl, naphthalene-2,6-diyl, decalin-2,6 - groups of diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and perylene-2,7-diyl, wherein groups a), b) and c) may be mono- or polysubstituted by halogen atoms, and Z ¹ and Z ¹ * each independently represent -CO-O-, -O-CO-, -CF ₂ O-, -OCF ₂ -, - CH ₂ O-, -OCH ₂ -, -CH ₂ -, -CH ₂ CH ₂ -, -(CH ₂ ) ₄ -, -CH=CH-CH ₂ O-, -C ₂ F ₄ -, -CH ₂ CF ₂ -, -CF ₂ CH ₂ -, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or single bond, a and b are independently 0 or 1, X represents -S- or -O-, and L ¹ and L ² each independently of one another represent F, Cl, CF ₃ or CHF ₂ , and at least one compound of formula ST below, or a polymer comprising the polymerized form thereof , P-Sp-(A ² -Z ² -A ¹ ) _m1 -Z ¹ -Pip ST wherein the individual radicals, independently of one another and at each occurrence identically or differently, have the following meanings: Pip is selected from radicals of the formula group

R ^g H or straight or branched chain alkyl or alkoxyalkyl having 1 to 10 C atoms, preferably 1 to 6 C atoms, most preferably 1 to 4 C atoms, or benzyl , preferably H, R ^a , R ^b , R ^c , R ^d have 1 to 10 C atoms, preferably 1 to 6 C atoms, and most preferably a straight or branched chain with 1 to 4 C atoms Alkyl, P vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl or epoxy, preferably acrylate, methyl Acrylate group, fluoroacrylate group, chloroacrylate group, more preferably acrylate group or methacrylate group, most preferably methacrylate group, Sp spacer group or single bond, A ¹ , A ² Alicyclic, heterocyclic, aromatic or heteroaromatic radicals having 4 to 30 ring atoms, which may also contain fused rings and optionally via one or more groups L or R-(A ³ -Z ³ ) _m2 -substituted, and one of A ¹ and A ² may also represent a single bond, A ³ has an alicyclic group, a heterocyclic group, an aromatic group or a heteroaromatic group with 4 to 30 ring atoms, which It can also contain fused rings and is optionally substituted by one or more groups L, Z ¹ -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O -, -OCH ₂ -, -CH ₂ O-, -SCH ₂ -, -CH ₂ S-, -CF ₂ O-, -OCF ₂ -, -CF ₂ S-, -SCF ₂ -, -(CH ₂ ) _n -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ -, -(CF ₂ ) _n -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH ₂ -CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ -, -CR ⁰⁰ R ⁰⁰⁰ - or a single bond, the limitation is that if m1 is 0, then Z ¹ is a single bond, Z ² , Z ³ -O-, -S-, -CO-, -CO-O-, -O-CO-, -O- _CO - _O- , _-OCH2- , _-CH2O- , _-SCH2- , -CH2S-, -CF2O-, _-OCF2- , _-CF2 S-, -SCF ₂ -, -(CH ₂ ) _n -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ -, -(CF ₂ ) _n -, -CH=CH-, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH ₂ -CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ -, -CR ⁰⁰ R ⁰⁰⁰ - or single bond, R ^{0 0} , R ⁰⁰⁰ H or an alkyl group with 1 to 12 C atoms, R P-Sp-, H, F, Cl, CN or a straight chain, branched chain alkyl group or cycloalkyl group with 1 to 25 C atoms , wherein one or more non-adjacent CH ₂ -groups are optionally connected via -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- replacement, and one or more of the H atoms are each replaced as appropriate by F, Cl or P-Sp- or the group Pip, L P-Sp-, F, Cl , CN, or straight-chain, branched-chain alkyl or cycloalkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH ₂ -groups are optionally separated by O- and/or S- atoms Direct attachment is replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O-, and one or more H atoms are each optionally replaced by F, Cl or P-Sp- or group substitution selected from formulae 1, 2 and 3, m1 0, 1, 2, 3 or 4, m2 0, 1, 2, 3 or 4, and n 1, 2, 3 or 4. Compounds of the formula ST have been proposed as additives in polymerizable liquid-crystalline media in WO 2016/116119 A1. Media of this type can be used in particular for electro-optic displays with active matrix addressing based on the ECB effect and for IPS (Coplanar Switching) displays or FFS (Fringe Field Switching) displays.

其中 L¹ 、L² 獨立地為H或F，其中L¹ 及L² 中之至少一者為F， L³ 、L⁴ 獨立地為H或F，其中L³ 及L⁴ 中之至少一者為F， R 各自彼此獨立地表示H、具有1至15個C原子之烷基或烷氧基，其中，另外，此等基團中之一或多個CH₂ 基團可各自彼此獨立地以O原子不彼此直接連接之方式由以下置換：-C≡C-、-CF₂ O-、-OCF₂ -、-CH=CH-、

、

、-O-、-CO-O-、-O-CO-，且其中另外，一或多個H原子可經鹵素置換， 較佳為具有1至6個C原子之直鏈烷基或烷氧基， 烷基 具有1至6個C原子之直鏈或分支鏈，較佳地直鏈烷基， n 0或1，較佳地1，及 (O) 為-O-或單鍵，較佳地-O-。 在較佳實施例中，液晶介質包含至少一種式I化合物、至少一種式ST之化合物及一或多種式T化合物。 較佳地式T化合物係選自以下子式：

其中 R表示具有1至6個C原子之直鏈烷基或烷氧基，且m=0、1、2、3、4、5或6。在此等化合物中，R較佳地表示烷基，各自具有1至5個C原子。 R較佳表示甲基、乙基、丙基、丁基、戊基、己基、甲氧基、乙氧基、丙氧基、丁氧基或戊氧基。 根據本發明之介質較佳包含式T-1至T-5之聯三苯，其量為2-30重量%，尤其3-20重量%。 尤其較佳為式T-1至T-3之化合物，且更特定而言為式T-1之化合物。 若混合物之Δn值≥ 0.1，則聯三苯基較佳用於根據本發明之混合物中。較佳混合物包含2-20重量%的一或多種選自化合物T-1至T-5之群的聯三苯化合物。 根據本發明之混合物較佳展現極廣泛的向列型相範圍，其中澄清點≥ 70℃，較佳≥ 75℃，尤其≥ 80℃；相對較高之保持率值、極有利之電容臨限值及同時在-20℃及-30℃下極良好之低溫穩定性，以及極低旋轉黏度值及短回應時間。此外，藉由除旋轉黏度γ₁ 改良之外，亦可觀測到用於改良回應時間之相對較高的彈性常數K₃₃ 值之事實來區分根據本發明之混合物。在較佳具有負性介電各向異性之LC混合物中使用式I化合物，降低旋轉黏度γ₁ 及彈性常數K_i 之比率。 本發明亦係關於一種用於製備根據本發明之液晶介質之方法，其中至少一種式I化合物及至少一種式ST化合物與至少一種另外液晶化合物混合，且視情況添加一或多種添加劑。 以下指示根據本發明之混合物之一些較佳實施例。 式ST化合物較佳地用於濃度在0.0005重量%到2重量%範圍內，更佳地0.001重量%至1重量%範圍內，尤佳0.005重量%至0.05%範圍內之液晶介質中。 根據本發明之液晶介質中之可聚合或聚合組分之總含量較佳為低於0.1重量%，更佳為低於0.05重量%，且最佳小於0.02重量% (200 ppm)。 在一較佳實施例中，液晶介質包含至少一種式I化合物、至少一種式ST化合物及一或多種式L化合物。最佳地液晶介質包含至少一種式I化合物、至少一種式ST化合物、一或多種式T化合物及一或多種式L化合物。 較佳之式L化合物選自以下子式L-1及L-2：

其中 R 彼此獨立地表示H、具有至多15個C原子的未經取代、經CN或CF₃ 單取代或經鹵素至少單取代之烷基或烯基，此外其中，在此等基團中之一或多個CH₂ 基團可以O原子彼此不直接連接之方式經以下置換：-O-、-S-、

、-C≡C-、-CF₂ O-、-OCF₂ -、-OC-O-或-O-CO-，及 烷基表示具有1至6個C原子之烷基。 在式I化合物中，R¹ 及R^{1 *} 較佳各自彼此獨立地表示直鏈烷氧基，尤其OCH₃ 、正C₂ H₅ O、正OC₃ H₇ 、正OC₄ H₉ 、正OC₅ H₁₁ 、正OC₆ H₁₃ ；此外烯基，尤其CH₂ =CH₂ 、CH₂ CH=CH₂ 、CH₂ CH=CHCH₃ 、CH₂ CH=CHC₂ H₅ ；分支鏈烷氧基，尤其OC₃ H₆ CH(CH₃ )₂ ；及烯基氧基，尤其OCH=CH₂ 、OCH₂ CH=CH₂ 、OCH₂ CH=CHCH₃ 、OCH₂ CH=CHC₂ H₅ 。 R¹ 及R^{1 *} 尤其較佳各自彼此獨立地表示具有1至6個C原子之直鏈烷氧基，尤其甲氧基、乙氧基、丙氧基、丁氧基、戊氧基、己氧基。 A¹ 及A^{1 *} 較佳地表示1,4-環己烷或1,4-伸苯基。 較佳地參數a及b均為0，或替代地a為1且b為0。最佳地a=b=0。 式I中之L¹ 及L² 較佳地均表示F。 更佳地式I化合物為式I-1至式I-20之化合物，

其中 烷基及烷基*各自彼此獨立地表示具有1至6個C原子之直鏈烷基，烯基及烯基*各自彼此獨立地表示具有2至6個C原子之直鏈烯基，烷氧基及烷氧基*各自彼此獨立地表示具有1至6個C原子之直鏈烷氧基，且L¹ 及L² 各自彼此獨立地表示F或Cl。 在式I-1至I-20之化合物中，L¹ 及L² 較佳地各自彼此獨立地表示F或Cl，尤其L¹ =L² =F。尤其較佳為式I-2及I-6之化合物。在式I-2及I-6之化合物中，較佳為L¹ =L² =F。 根據本發明之混合物極其較佳地包含至少一種選自下文所展示之式I-1A、I-2A、I-4A、I-6A、I-6B、I-11A、I-12-A、I-14A及I-16A之化合物之群之化合物：

極尤其較佳之混合物包含至少一種選自以下式之化合物之群之化合物：

式I化合物可例如根據US 2015/0259602 A、US 9,512,102 B、US 2005/0258399 A或US 2004/124399 A中所描述而製備。 根據本發明之介質較佳包含一種、兩種、三種、四種或更多種，較佳一種、兩種或三種式I化合物。 以整體混合物計，式I化合物較佳以≥ 1重量%，較佳≥ 3重量%之量用於液晶介質中。尤其較佳為包含1-40重量%，極其較佳地2-30重量%之一或多種式I化合物之液晶介質。 式ST之化合物，尤其較佳其中Pip為選自以下式之基團之式之化合物

或

其中 R^a 、R^b 、R^c 、R^d 獨立地為具有1至10個C原子之直鏈或分支鏈烷基。 較佳地，式ST中之Z¹ 表示-CO-O-、-O-CO-或單鍵，極佳-CO-O-或單鍵。 較佳地，式ST中之Z² 及Z³ 表示-CO-O-、-O-CO-或單鍵，極佳為單鍵。 較佳地，式ST中之P為丙烯酸酯基或甲基丙烯酸酯基。 較佳地，式ST中之Sp為單鍵。 較佳地，式I中之R^g 為H。 較佳地，式ST中之A³ 表示具有6至24個環原子之亦可含有稠合環且視情況經一或多個基團L取代之芳族或雜芳族基團。 極佳地，式ST中之A³ 表示視情況經一或多個基團L取代之苯或萘。 較佳地，式ST中之A¹ 及A² 表示具有6到24個環原子之亦可含有稠合環且視情況經一或多個基團L或R-(A³ -Z³ )_m2 -取代之芳族或雜芳族基團，或A¹ 為單鍵。 極佳地，式ST中之A¹ 及A² 表示視情況經一或多個基團L或-(A³ -Z³ )_m2 -取代之苯、伸環己基、萘、菲或蒽，或A¹ 為單鍵。 較佳地，式ST中之-(A² -Z² -A¹ )_m1 -表示苯、聯伸二苯、對聯伸三苯(1,4-二苯基苯)、間聯伸三苯(1,3-二苯基苯)、伸萘基、2-苯基-伸萘基、菲或蒽，其所有視情況經一或多個基團L取代。 極佳地，-(A² -Z² -A¹ )_m1 -表示聯伸二苯、對聯伸三苯或間聯伸三苯，其所有視情況經一或多個基團L取代。 較佳基團-(A² -Z² -A¹ )_m1 -係選自下式

其中L如式ST中所定義或具有如上文及下文所描述之較佳含義中之一者，r為0、1、2、3或4，s為0、1、2或3，t為0、1或2，且u為0、1、2、3、4或5。 尤其較佳為式A1、A2、A3、A4及A5之基團。 根據本發明之極尤其較佳混合物包括選自以下子式之一或多種穩定劑

其中P、Sp、R^{a - d} 、Z¹ 、L及R如式ST中所定義或具有如上文及下文所描述之較佳含義中之一者， R^e 為具有1至12個C原子之烷基， r為0、1、2、3或4，及 s為0、1、2或3。 較佳地，式ST及ST-1至ST-45中之Z¹ 為-CO-O-、-O-CO-或單鍵，極佳-CO-O-或單鍵。 較佳地，式ST及ST-1至ST-45中之P為丙烯酸酯基或甲基丙烯酸酯基。 較佳地，式ST及ST-1至ST-45中之Sp為單鍵。 較佳地，式ST及ST-1至ST-45中之R^a 、R^b 、R^c 及R^d 為甲基。 較佳地，ST-1至ST-45中之結構為結構ST-1及ST-23。 更佳地，式ST及其子式ST-1至ST-45之化合物獨立地選自以下較佳實施例，包括其任何組合： - 該等化合物恰好含有一種可聚合基團(表示為基團P)， - 當不同於單鍵時，Sp選自-(CH₂ )_a -O-、-(CH₂ )_a -CO-O-、-(CH₂ )_a -及-(CH₂ )_a -O-CO-，其中a為2、3、4、5或6，且O-原子或CO-基團分別連接至下一環A² 或基團Pip，若適用， - R^e 為甲基、乙基、正丙基、異丙基、第三丁基、正丁基或正戊基， - m1為0、1或2， - m2為0、1或2， - Z¹ 表示-CO-O-、-O-CO-或單鍵，較佳-CO-O-， - Z² 表示-CO-O-、-O-CO-或單鍵，較佳單鍵， - L表示F、Cl、CN或具有1至6個C原子之視情況經氟化之烷基或烷氧基，極佳F、Cl、CN、CH₃ 、OCH₃ 、OCF₃ 、OCF₂ H或OCFH₂ ，最佳F， - L中之一或多者表示基團Pip， - r為0或1， - s為0， - t為0， - u為0、1或2。 本發明之液晶介質之較佳實施例如下所指示： a) 另外包含一或多種選自式IIA、式IIB及式IIC之化合物之群的化合物的液晶介質，

其中 R^2A 、R^2B 及R^2C 各自彼此獨立地表示H、具有至多15個C原子的未經取代、經CN或CF₃ 單取代或經鹵素至少單取代之烷基或烯基，此外其中，在此等基團中之一或多個CH₂ 基團可以O原子彼此不直接連接之方式經以下置換：-O-、-S-、

、-C≡C-、-CF₂ O-、-OCF₂ -、-OC-O-或 -O-CO-， L^1-4 各自彼此獨立地表示F、Cl、CF₃ 或CHF₂ ， Z² 及Z^{2 '} 彼此獨立地各自表示單鍵、-CH₂ CH₂ -、-CH=CH-、-CF₂ O-、-OCF₂ -、-CH₂ O-、-OCH₂ -、-COO-、-OCO-、-C₂ F₄ -、-CF=CF-、-CH=CHCH₂ O-， -(O)C_v H_2v+1 表示-O-C_v H_2v+1 或-C_v H_2v+1 ， p 表示0、1或2， q 表示0或1，及 v 表示1至6。 在式IIA及IIB之化合物中，Z² 可具有相同或不同含義。在式IIB之化合物中，Z² 及Z^{2 '} 可具有相同或不同含義。 在式IIA、式IIB及式IIC之化合物中，R^2A 、R^2B 及R^2C 各自較佳表示具有1至6個C原子的烷基，尤其CH₃ 、C₂ H₅ 、正C₃ H₇ 、正C₄ H₉ 、正C₅ H₁₁ 。 在式IIA及IIB之化合物中，L¹ 、L² 、L³ 及L⁴ 較佳表示L¹ = L² = F，且L³ = L⁴ = F，另外L¹ = F，且L² = Cl，L¹ = Cl，且L² = F，L³ = F，且L⁴ = Cl，L³ = Cl，且L⁴ = F。式IIA及IIB中之Z² 及Z^{2 '} 較佳各自彼此獨立地表示單鍵，另外-C₂ H₄ -橋。 若在式IIB中，Z² = -C₂ H₄ -或-CH₂ O-，則Z^{2 '} 較佳為單鍵；或若Z^{2 '} = -C₂ H₄ -或-CH₂ O-，則Z² 較佳為單鍵。在式IIA及IIB之化合物中，(O)C_v H_{2v + 1} 較佳地表示OC_v H_{2v + 1} 。在式IIC化合物中，(O)C_v H_{2v + 1} 較佳表示C_v H_{2v + 1} 。在式IIC之化合物中，L³ 及L⁴ 較佳各自表示F。 較佳之式IIA、IIB及IIC之化合物如下所指示：

其中 烷基及烷基* 各自彼此獨立地表示具有1至6個C原子的直鏈烷基，及 烯基及烯基* 各自彼此獨立地表示具有2至6個C原子之直鏈烯基。 根據本發明之尤其較佳混合物包含一或多種式IIA-2、IIA-8、IIA-14、IIA-26、II-28、IIA-33、IIA-39、IIA-45、IIA-46、IIA-47、IIA-50、IIB-2、IIB-11、IIB-16及IIC-1之化合物。 式IIA及/或式IIB之化合物在整個混合物中之比例較佳為至少20重量%。 本發明之尤其較佳介質包含至少一種式IIC-1之化合物，

， 其中烷基及烷基*具有上文所指出之含義，其量較佳為＞3重量%，尤其＞5重量%且尤其較佳5-25重量%。 b) 液晶介質，其另外包含一或多種式III化合物，

其中 R³¹ 及R³² 各自彼此獨立地表示具有至多12個C原子之直鏈烷基、烷氧基、烯基、烷氧基烷基或烷氧基，且

表示

或

Z³ 表示單鍵、-CH₂ CH₂ -、-CH=CH-、-CF₂ O-、-OCF₂ -、-CH₂ O-、-OCH₂ -、-COO-、-OCO-、-C₂ F₄ -、-C₄ H₈ -、-CF=CF-。 較佳式III化合物如下所指示：

其中 烷基及烷基* 各自彼此獨立地表示具有1至6個C原子的直鏈烷基。 根據本發明之介質較佳包含至少一種式IIIa及/或式IIIb之化合物。 式III之化合物在整個混合物中之比例較佳為至少5重量%。 c) 液晶介質，其另外包含下式之化合物

， 較佳總量為≥ 5重量%、尤其≥ 10重量%。 此外，較佳為包含以下化合物(縮寫字：CC-3-V1)之本發明混合物

， 較佳地量為2-15重量%。 較佳混合物包含5-60重量%，較佳10-55重量%，尤其20-50重量%之下式化合物(縮寫字：CC-3-V)

。 另外，較佳為包含下式之化合物(縮寫字：CC-3-V)

及下式化合物(縮寫字：CC-3-V1)之混合物

， 其較佳量為10-60重量%。 d) 液晶介質，其另外包含一或多種下式之四環化合物：

其中 R^7-10 各彼此獨立地具有技術方案5中關於R^2A 所指示之含義中之一者，且 w及x 各自彼此獨立地表示1至6。 尤其較佳為包含至少一種式V-9化合物之混合物。 e) 液晶介質，其另外包含一或多種式Y-1至Y-6之化合物，

其中R¹⁴ 至R¹⁹ 各自彼此獨立地表示具有1至6個C原子之烷基或烷氧基；z及m各自彼此獨立地表示1至6；x表示0、1、2或3。 根據本發明之介質尤其較佳包含一或多種式Y-1至Y-6之化合物，其量較佳≥5重量%。 f) 液晶介質，其另外包含一或多種式TF-1至TF-21之氟化聯三苯基，

其中 R表示具有1至6個C原子之直鏈烷基或烷氧基，且m=0、1、2、3、4、5或6及n表示0、1、2、3或4。 R較佳表示甲基、乙基、丙基、丁基、戊基、己基、甲氧基、乙氧基、丙氧基、丁氧基、戊氧基。 根據本發明之介質較佳包含式TF-1至TF-21之聯三苯，其量為2-30重量%，尤其5-20重量%。 尤其較佳為式TF-1、TF-2、TF-4、TF-20及T-21化合物。在此等化合物中，R較佳表示烷基，此外表示烷氧基，其各自具有1至5個C原子。在式TF-20化合物中，R較佳表示烷基或烯基，尤其烷基。在式TF-21化合物中，R較佳表示烷基。 若混合物之Δn值≥ 0.1，則聯三苯基較佳用於根據本發明之混合物中。較佳混合物包含2-20重量%的一或多種選自化合物TF-1至TF-21之群的聯三苯化合物。 g) 液晶介質，其另外包含一或多種式PP-1至PP-3之聯苯基，

其中 烷基及烷基* 各自彼此獨立地表示具有1至6個C原子的直鏈烷基，及 烯基及烯基* 各自彼此獨立地表示具有2至6個C原子之直鏈烯基。 式PP-1至PP-3之聯苯基在整個混合物中之比例較佳為至少3重量%、尤其≥5重量%。 在式PP-1至PP-3之化合物中，式PP-2化合物為尤其較佳的。 尤佳地，聯苯基為

其中烷基*表示具有1至6個C原子之烷基。根據本發明之介質尤其較佳包含一或多種式PP-1a及/或PP-2c之化合物。 h) 液晶介質，其包含至少一種式Z-1至Z-7之化合物，

其中R及烷基具有上文所指示之含義。 i) 液晶介質，其另外包含至少一種式O-1至O-18之化合物，

其中R¹ 及R² 具有關於R^2A 所指示之含義。R¹ 及R² 較佳各彼此獨立地表示直鏈烷基或烯基。 較佳介質包含一或多種式O-1、O-3、O-4、O-6、O-7、O-10、O-11、O-12、O-14、O-15、O-16及/或O-17之化合物。 根據本發明之混合物極尤其較佳包含式O-10、O-12、O-16及/或O-17之化合物，尤其其量為5-50%。 較佳之式O-10及O-17之化合物如下所指示：

根據本發明之介質尤其較佳包含式O-10a及/或式O-10b之三環化合物以及一或多種式O-17a至O-17i之雙環化合物。式O-10a及/或O-10b之化合物以及一或多種選自式O-17a至O-17i之雙環化合物的化合物之總比例為5%至55%，極尤其較佳為15%至40%。 極尤其較佳混合物包含化合物O-10a及O-17a：

。 以整個混合物計，化合物O-10a及O-17a較佳以15至50%、尤其較佳25至45%且特別較佳25-35%之濃度存在於混合物中。 極尤其較佳混合物另外包含化合物O-17b及O-17i中之一或多者：

以兩個化合物之整個混合物計，化合物O-17b及O-17i較佳地以5至20%，尤佳8至15%之濃度存在於混合物中。 j) 根據本發明之較佳液晶介質包含一或多種含有四氫萘基或萘基單元之物質，諸如式N-1至N-5之化合物，

其中R^1N 及R^2N 各自彼此獨立地具有關於R^2A 所指示含義，較佳表示直鏈烷基、直鏈烷氧基或直鏈烯基，且 Z¹ 及Z² 各自彼此獨立地表示-C₂ H₄ -、-CH=CH-、-(CH₂ )₄ -、-(CH₂ )₃ O-、-O(CH₂ )₃ -、-CH=CHCH₂ CH₂ -、-CH₂ CH₂ CH=CH-、-CH₂ O-、-OCH₂ -、-COO-、-OCO-、-C₂ F₄ -、-CF=CF-、-CF=CH-、-CH=CF-、-CF₂ O-、-OCF₂ -、-CH₂ -或單鍵。 k) 較佳混合物包含一或多種選自式BC之二氟二苯并色滿化合物、式CR之色滿、式PH-1及PH-2之氟化菲、式BF-1及BF-2之氟化二苯并呋喃之群的化合物，

其中 R^B1 、R^B2 、R^CR1 、R^CR2 、R¹ 、R² 各自彼此獨立地具有R^2A 之含義。c為0、1或2且d表示1或2。R¹ 及R² 較佳地彼此獨立地表示具有1至6個C原子之烷基或烷氧基。式BF-1及BF-2之化合物不應等同於一或多種式I化合物。 根據本發明之混合物較佳包含呈3至20重量%之量、尤其呈3至15重量%之量之式BC、CR、PH-1、PH-2及/或BF之化合物。 尤其較佳式BC及CR之化合物為化合物BC-1至BC-7及CR-1至CR-5，

其中 烷基及烷基* 各自彼此獨立地表示具有1至6個C原子的直鏈烷基，及 烯基及烯基* 各自彼此獨立地表示具有2至6個C原子之直鏈烯基。 極尤其較佳為包含一種、兩種或三種式BC-2、BF-1及/或BF-2之化合物之混合物。 l) 較佳混合物包含一或多種式In之茚滿化合物，

其中 R¹¹ 、R¹² 、R¹³ 各自彼此獨立地表示具有1至6個C原子之直鏈烷基、烷氧基、烷氧基烷基或烯基， R¹² 及R¹³ 另外表示鹵素，較佳為F，

表示

， i 表示0、1或2。 較佳式In化合物為如下指示之式In-1至In-16之化合物：

。 尤其較佳為式In-1、式In-2、式In-3及式In-4之化合物。 式In及子式In-1至In-16之化合物較佳以≥5重量%，尤其是5-30重量%且極尤其較佳5-25重量%之濃度用於根據本發明之混合物中。 m) 較佳混合物另外包含一或多種式LY-1至LY-11之化合物，

其中 R、R¹ 及R² 各自彼此獨立地具有如技術方案5中R^2A 所指示之含義，且烷基表示具有1至6個C原子之烷基。s表示1或2。-(O)烷基表示-O-烷基或-烷基，較佳為-O-烷基。 尤其較佳混合物概念如下所指示：(在表A中闡述所用縮寫字。n及m在本文中各自彼此獨立地表示1至15，較佳1至6)。 根據本發明之混合物較佳包含 - 一或多種式I化合物，其中L¹ =L² =F且R¹ =R^{1 *} =烷氧基； - 一或多種式ST化合物，其中m為0或1； - 一或多種式L化合物，其中n為1； - 一或多種式CPY-n-Om，特定而言CPY-2-O2、CPY-3-O2及/或CPY-5-O2之化合物，以整個混合物計，較佳呈濃度＞5%，特定而言10-30%， 及 - 一或多種式CY-n-Om，較佳為CY-3-O2、CY-3-O4、CY-5-O2及/或CY-5-O4化合物，以整個混合物計，較佳呈濃度＞5%，特定而言5-25%， 及/或 - 一或多種式CCY-n-Om，較佳為CCY-4-O2、CCY-3-O2、CCY-3-O3、CCY-3-O1及/或CCY-5-O2化合物，以整個混合物計，較佳呈濃度＞5%，特定而言10-30%， 本發明另外係關於一種基於ECB、VA、PS-VA、PA-VA、IPS、PS-IPS、FFS或PS-FFS效應之具有主動式矩陣定址之電光顯示器，其中其含有根據技術方案中之一或多者之液晶介質作為介電質。 本發明之液晶介質較佳具有≤-20℃至≥70℃、尤其較佳≤-30℃至≥80℃、極尤其較佳≤-40℃至≥90℃之向列相。 表述「具有向列相」在本文中意謂：一方面，在相應溫度下在低溫下未觀察到近晶相及結晶，且另一方面，在加熱時自向列相仍不會出現清澈現象。低溫下之研究在相應溫度下於流量式黏度計中進行，且藉由儲存於層厚度對應於電光用途之測試單元中至少100小時來檢驗。若在相應測試單元中於-20℃溫度下之儲存穩定性為1000 h或更長時間，則稱該介質在此溫度下穩定。在-30℃及-40℃之溫度下，對應時間分別為500 h及250 h。在高溫下，利用習知方法在毛細管中量測澄清點。 液晶混合物較佳具有至少60 K之向列相範圍及在20℃下至多30 mm² · s^{- 1} 之流動黏度ν₂₀ 。 在液晶混合物中之雙折射Δn值一般在0.07與0.16之間，較佳在0.08與0.13之間。 根據本發明之液晶混合物具有-0.5至-8.0，尤其-2.5至-6.0之Δε，其中Δε表示介電各向異性。20℃下之旋轉黏度g₁ 較佳為≤150 mPa×s，特定而言≤120 mPa×s。 根據本發明之液晶介質具有相對較低之臨限電壓(V₀ )值。其較佳在1.7V至3.0V範圍內，尤其較佳為≤2.5V且極尤其較佳為≤2.3V。 對於本發明，除非另外明確指示，否則術語「臨限電壓」係指電容臨限值(V₀ )，亦稱為弗雷德里克臨限值(Freedericks threshold)。 另外，根據本發明之液晶介質在液晶單元中具有高電壓保持率值。 一般而言，相比於具有較高定址電壓或臨限電壓之液晶介質，具有低定址電壓或臨限電壓之液晶介質展現較低的電壓保持率，且反之亦然。 對於本發明，術語「正介電化合物」表示具有De ＞ 1.5之化合物，術語「中性介電化合物」表示具有-1.5 £ De £ 1.5之彼等化合物及術語「負介電化合物」表示具有De ＜ -1.5之彼等化合物。在本文中，化合物之介電各向異性藉由以下步驟測定：將10%化合物溶解於液晶主體中，且測定至少一個測試單元中所得混合物之電容，在各情形下該測試單元之層厚度為20 µm，且在1 kHz下具有垂直及均質表面配向。量測電壓通常為0.5 V至1.0 V，但總低於所研究之各別液晶混合物之電容臨限值。 對於本發明指示之所有溫度值均以℃為單位。 根據本發明之混合物適用於具有負De之IPS (共平面切換型)及UB-FFS (邊緣場切換型)應用。其另外適用於所有VA-TFT應用，諸如VAN、MVA、(S)-PVA、ASV、PSA (保持聚合物之VA)及PS-VA (穩定聚合物之VA)。 根據本發明之顯示器中之向列型液晶混合物一般包含兩種組分：A及B，其自身由一或多種個別化合物組成。 組分A具有顯著負介電各向異性且賦予向列相≤-0.5之介電各向異性。除一或多種式I化合物以外，其較佳包含式IIA、IIB及/或IIC之化合物，此外一或多種式T化合物。 組分A之比例較佳為45至100%，尤其60至100%。 對於組分A，較佳選擇具有De≤0.8之值的一種(或多種)個別化合物。必定為，此值愈負，在整個混合物中比例A愈少。 組分B具有明顯向列態，且在20℃下，流動黏度不大於30 mm² ·s^{- 1} 、較佳不大於25 mm² · s^{- 1} 。 自文獻，熟習此項技術者已知多種適合材料。尤其較佳為式O-17化合物。 在組分B中尤其較佳個別化合物為在20℃下流動黏度不大於18 mm² ·s^{- 1} 、較佳不大於12 mm² ·s^{- 1} 之極低黏度向列液晶。 組分B為單變性或互變性向列型，無近晶相且能夠在降至極低溫度時阻止液晶混合物中出現近晶相。舉例而言，若將各種高向列態材料添加至近晶液晶混合物中，則此等材料之向列態可經由所達成之近晶相的抑制程度進行比較。 對於熟習此項技術者不言而喻，根據本發明之IPS、FFS或VA混合物亦可包含例如H、N、O、Cl及F已經對應同位素置換之化合物。 根據本發明之混合物可另外包含習知添加劑，諸如穩定劑、抗氧化劑、UV吸收劑、奈米粒子、微米粒子等。 根據本發明之液晶顯示器之結構對應於常見幾何結構。舉例而言，較佳IPS顯示器在具有平面定向之兩個基板之間含有LC層，其中兩個電極配置於兩個基板中之僅一者上且較佳具有叉指形蜂巢形結構。在向電極施加電壓後，從而在其之間產生具有平行於LC層之顯著分量的電場。此導致層平面中之LC分子之再配向。對於負IPS，配向層之配向方向較佳垂直於交叉指電極。已報導所謂的FFS (「邊緣場切換」)顯示器(尤其參見S.H. Jung等人, Jpn. J. Appl. Phys., 第43卷, No. 3, 2004, 1028)，其在同一基板上含有兩個電極，該等電極中之一者以梳形方式經結構化且另一者為非結構化的。此外，已揭示FFS顯示器(參見S.H. Lee等人，Appl. Phys. Lett. 73(20), 1998, 2882-2883及S.H. Lee等人，Liquid Crystals 39(9), 2012, 1141-1148)，其具有與FFS顯示器相似的電極設計及層厚度，但包含具有負介電各向異性之LC介質層而非具有正介電各向異性之LC介質層。 上文及下文適用以下含義： 除非另外說明，否則如本文所用之術語「可聚合化合物」應理解為意謂可聚合單體化合物。 上文及下文之術語「間隔基團」或簡稱「間隔基」，亦稱為「Sp」為熟習此項技術者已知且描述於文獻中，參見例如Pure Appl. Chem. 73(5), 888 (2001)及C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. (2004), 116, 6340-6368中。除非另外指示，否則上文及下文之術語「間隔基團」或「間隔基」表示在可聚合液晶原基化合物中將液晶原基基團及可聚合基團彼此連接之可撓性基團。儘管液晶原基基團一般含有環，但間隔基團一般為無環系統，亦即呈鏈形式，其中鏈亦可為分支鏈。術語鏈係用於例如伸烷基。鏈上及鏈中一般包括例如由-O-或-COO-進行之取代。在官能性術語中，間隔基(間隔基團)為分子的官能性結構部分之間的鍵聯基團，其有助於此等部分之間的某種空間可撓性。在一較佳實施例中，間隔基表示伸烷基(如-(CH₂ )_{n -} 且n=1至10)或伸烷基氧基，其較佳具有2至5個碳原子。 術語「鹵素」係指氟、氯或溴，較佳為氟或氯且尤其係指氟。類似地使用術語鹵化。 在整個專利申請案中，1,4-伸環己基環及1,4-伸苯基環描繪如下：

；

。 1,4-經取代伸環己基環為反-1,4-伸環己基環。 以下實例旨在解釋本發明，而不對其進行限制。在上文及下文中，百分比資料表示重量百分比；所有溫度均以攝氏度表示。 在整個專利申請案及工作實例中，藉助於縮寫字指示液晶化合物之結構。除非另外指示，否則根據表1-3進行向化學式之轉化。所有基團C_n H_{2n + 1} 、C_m H_{2m + 1} 及C_{m '} H_{2m ' + 1} 或C_n H_2n 及C_m H_2m 為在各情況下分別具有n、m、m'或z個C原子之直鏈烷基或伸烷基。n、m、m'、z各自彼此獨立地表示1、2、3、4、5、6、7、8、9、10、11或12，較佳1、2、3、4、5或6。在表1中，將各別化合物之環要素編碼，在表2中，列出橋接成員，且在表3中，指示化合物之左側或右側側鏈之符號的含義。表 1 ：環要素

表 2 ：橋接成員

表 3 ：側鏈

除一或多種式I化合物外，根據本發明之混合物較佳包含如下自表A中所提及之化合物之一或多種化合物。表 A 使用以下縮寫： (n、m、m'、z：各自彼此獨立地為1、2、3、4、5或6； (O)C_m H_2m+1 意謂OC_m H_2m+1 或C_m H_2m+1 )

可根據本發明所使用之液晶混合物以本身習知之方式製備。一般而言，宜在高溫下將以較少量使用之所要量之組分溶解於構成主要成分之組分中。亦有可能在有機溶劑中，例如在丙酮、氯仿或甲醇中混合各組分之溶液，且有可能例如藉由在充分混合後蒸餾來再次移除溶劑。 藉助於適合添加劑，根據本發明之液晶相可經改質以使得其可用於迄今已揭示之任何類型(例如ECB、VAN、IPS、GH或ASM-VA LCD)顯示器中。 介電質亦可包含熟習此項技術者已知及文獻中所描述之其他添加劑，諸如UV吸收劑、抗氧化劑、奈米粒子及自由基清除劑。舉例而言，可添加0-15%的多色染料、穩定劑，諸如酚類、HALS (受阻胺光穩定劑)或對掌性摻雜劑。適合於根據本發明之混合物的穩定劑尤其為表C中所列的彼等物質。 舉例而言，可添加0-15%之多色染料，此外可添加導電鹽，較佳為4-己氧基苯甲酸乙基二甲基十二烷基銨、四苯基氫硼化四丁基銨或冠醚之複合鹽(參見例如Haller等人, Mol. Cryst. Liq. Cryst., 第24卷, 第249頁至第258頁(1973))以改良導電性，或可添加物質以改良向列相之介電各向異性、黏度及/或配向。此類型物質描述於(例如) DE-A 22 09 127、22 40 864、23 21 632、23 38 281、24 50 088、26 37 430及28 53 728中。表 B 表B指示可添加至根據本發明之混合物中之可能的摻雜劑。若混合物包含摻雜劑，則其以0.01至4重量%、較佳0.01至3重量%之量添加。

根據本發明之混合物包含來自下文給出表C之至少一種穩定劑。表 C 可以0至10重量%、較佳0.001至5重量%、尤其0.001至1重量%之量例如添加至根據本發明之混合物的穩定劑指示如下。

n = 1、2、4、5、6或7

n = 1、2、4、5、6或7

n = 2、3、4、5或6

工作實例 以下實例旨在解釋本發明，而不對其進行限制。在實例中，m.p.表示液晶物質之熔點(以攝氏度計)且C表示液晶物質之澄清點(以攝氏度計)；沸點溫度由m.p.表示。另外：C表示結晶固體狀態，S表示近晶相(指數表示相類型)，N表示向列狀態，Ch表示膽固醇狀液晶相，I表示各向同性相，T_g 表示玻璃轉移溫度。兩個符號之間的數字指示以攝氏度an表示之轉化溫度。 用於測定式I化合物之光學各向異性Δn的主體混合物為市售混合物ZLI-4792 (Merck KGaA)。使用市售混合物ZLI-2857測定介電各向異性Δε。待研究化合物之物理資料由在添加待研究化合物之後主體混合物之介電常數的變化且外推至100%所用化合物而獲得。一般而言，視溶解性而定，將10%之待研究化合物溶解於主體混合物中。 除非另外指示，否則份數或百分比資料表示重量份或重量百分比。 上文及下文： V_o 表示在20℃下之電容臨限電壓[V]， n_e 表示在20℃及589 nm下之異常折射率， n_o 表示在20℃及589 nm下之普通折射率， Dn 表示在20℃及589 nm下之光學各向異性， e_^ 表示在20℃及1 kHz下，垂直於引向器之介電電容率， e_÷÷ 表示在20℃及1 kHz下，與引向器平行之介電電容率， De 表示在20℃及1 kHz下之介電各向異性， cl.p., T(N,I) 表示澄清點[℃]， g₁ 表示在20℃下所量測之旋轉黏度[mPa∙s]，其藉由旋轉方法在磁場中測定， K₁ 表示彈性常數，在20℃下之「傾斜」變形[pN]， K₂ 表示彈性常數，在20℃下之「扭曲」變形[pN]， K₃ 表示彈性常數，在20℃下之「彎曲」變形[pN]， LTS 表示在測試單元中測定之低溫穩定性(向列相)。 除非另外明確指出，否則本申請案之所有指示值均針對溫度，諸如熔點T (C,N)、自近晶(S)至向列(N)相位T(S,N)之過渡及澄清點T (N,I)均以攝氏度(℃)指示。M.p.表示熔點，cl.p. =澄清點。此外，Tg =玻璃態，C =結晶態，N =向列相，S =近晶相且I =各向同性相。在此等符號之間的數字表示轉移溫度。 對於本發明，除非另外明確指示，否則術語「臨限電壓」係指電容臨限值(V₀ )，亦稱為弗雷德里克臨限值。在實例中，如一般常用，光學臨限值亦可針對10%相對對比度(V₁₀ )指示。 用於量測電容臨限電壓之顯示器由兩個間距20 µm之平面平行的玻璃外板組成，其各自在內側上具有電極層，且在頂部具有無摩擦之聚醯亞胺配向層，其實現液晶分子之垂直邊緣配向。 用於量測傾斜角之顯示器或測試單元由兩個間距為4 µm之平面平行的玻璃外板組成，其各在內側上具有電極層且在頂部具有聚醯亞胺配向層，其中兩個聚醯亞胺層彼此反向平行地摩擦，且實現液晶分子之垂直邊緣配向。 可聚合化合物在顯示器或測試單元中，藉由用限定強度之UVA光(通常365 nm)照射預先設定之時間來聚合，同時將電壓施加至顯示器(通常10 V至30 V交流電，1 kHz)。在實例中，除非另外指示，否則使用50 mW/cm² 汞蒸氣燈，且使用配有365 nm帶通濾光器之標準UV儀(製作Ushio UNI儀錶)量測強度。 由旋轉晶體實驗(Autronic-Melchers TBA-105)測定傾角。此處低值(亦即與90°角之大偏差)對應於大傾斜。 如下量測VHR值：將液晶介質引入至TN-VHR測試單元(如所指示之配向層)中。在60℃下5分鐘之後在1 V，60 Hz，64 µs脈衝下UV曝光之前及之後測定HR值(量測儀器：Autronic-Melchers VHRM-105)。 為了研究低溫穩定性，亦稱為「LTS」，亦即在低溫下LC混合物自發結晶出個別組分之穩定性，將含有1 g LC/RM混合物之瓶子儲存在-10℃下，且定期檢查混合物是否結晶出。 所謂的「HTP」表示在LC介質中光學活性或對掌性物質之螺旋扭轉力(以μm為單位)。除非另外指示，否則HTP係以在20℃之溫度下之市售可得向列LC主體混合物MLD-6260 (Merck KGaA)進行量測。 除非另外明確指出，否則本申請案中之所有濃度均以重量百分比指示，且係指包含所有固體或液晶組分之整個對應混合物(無溶劑)。除非另外明確指示，否則所有物理性質均根據「Merck Liquid Crystals, Physical Properties of Liquid Crystals」, Status 1997年11月, Merck KGaA, Germany測定，且適用於20℃之溫度。 使用以下可聚合穩定劑(可聚合哌啶衍生物)：

來源：Santa Cruz Inc. (CAS 31582-45-3)

添加劑之合成實例 例示性式I化合物如下或根據WO 2016/116119 A1(實例)合成。合成實例 可如下製備化合物STF - 2 。

將4-羥基TEMPO (8.00 g，45.5 mmol)及4-(二甲胺基)吡啶(0.30 g，2.46 mmol)添加至100 ml DCM中。在冷卻至2℃之後，將三乙胺(25.00 ml，180.35 mmol)添加至以上溶液中，接著將3-溴-丙醯氯(6.00 ml，50.6 mmol)逐滴添加至50 ml DCM中。在完成添加之後，使反應混合物升溫至室溫。在完成藉由TLC指示之轉換之後，添加氯化銨水溶液。用DCM萃取水相。合併有機相且經無水硫酸鈉乾燥且過濾。在真空中移除溶劑之後，使用DCM/甲基第三丁基醚(MTBE) 95:5作為溶離劑藉由矽膠管柱層析純化固體殘餘物，且自庚烷/MTBE進一步再結晶以得到呈紅色晶體之STF - 2 (m.p.102℃)。 以下具有負性介電各向異性之混合物實例尤其適用於具有至少一個平面配向層之液晶顯示器，諸如IPS及FFS顯示器，尤其UB-FFS (=超亮FFS)，且適用於VA顯示器。混合物實例 實例 M1 以下液晶混合物

另外包含0.01%之STF-1 (實例1)及STF-2 (實例2)。 包含穩定劑之實例M1之混合物藉由應力測試之後極好可靠度及高VHR值來區分。比較實例 A 根據實例M1但省略穩定劑STF-1/2，來製備比較液晶混合物(實例A)。VHR 量測 ： 可聚合哌啶衍生物在背光負載下之效應 由具有摩擦聚醯亞胺表面之玻璃板所組成的測試單元充滿先前實例M1及比較實例A之介質。在充分光負載(120 min)前後量測測試單元之電壓保持率(VHR)。照射光等效於500 h之用於顯示器的典型白色CCFL背光。 表1：摩擦聚醯亞胺(OPTMER®AL16301,JSR Corp.) 之結果：

*BL = 背光負載測試；120 h加速的基於LED的背光The present invention is based on the aim of providing liquid crystal mixtures, especially for monitor and TV applications, which do not have the disadvantages indicated above, or have only a reduced degree of the above, based on the IPS or UB-FFS effect or the ECB effect Disadvantages of instructions. In particular, it must be ensured that monitors and TVs also operate at very high and very low temperatures, and at the same time have very short response times and at the same time have improved reliability behavior, especially after long operating times without exhibiting image sticking or exhibiting significant reductions image retention. Surprisingly, it is possible to obtain fast response times of LC mixtures with good reliability by using compounds of formula I with the addition of suitable stabilizers. A reliability parameter that may be particularly affected herein is the voltage retention after exposure, such as exposure to UV light (sunlight test) or exposure to the backlight of an LCD. Use of this type of stabilizer increases voltage retention after exposure. The invention therefore relates to a liquid-crystalline medium comprising at least one compound of the formula I, at least one compound of the formula ST, and optionally preferably one or more compounds necessarily derived from the formula T and the formula L

wherein L ¹ , L ² are independently H or F, wherein at least one of L ¹ and L ² is F, L ³ , L ⁴ are independently H or F, wherein at least one of L ³ and L ⁴ For F, R each independently of one another represents H, an alkyl group having 1 to 15 C atoms or an alkoxy group, wherein, in addition, one or more CH ₂ groups of these groups can each independently of one another be represented by The way in which the O atoms are not directly connected to each other is replaced by the following: -C≡C-, -CF2O-, _-OCF2- , -CH= _CH- ,

,

, -O-, -CO-O-, -O-CO-, and wherein in addition, one or more H atoms may be replaced by halogen, preferably straight chain alkyl or alkoxy having 1 to 6 C atoms Alkyl, straight or branched chain with 1 to 6 C atoms, preferably straight chain alkyl, n 0 or 1, preferably 1, and (O) is -O- or a single bond, preferably Ground -O-. In a preferred embodiment, the liquid-crystalline medium comprises at least one compound of formula I, at least one compound of formula ST and one or more compounds of formula T. Preferably the compound of formula T is selected from the following sub-formulas:

wherein R represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, and m=0, 1, 2, 3, 4, 5 or 6. In these compounds, R preferably represents an alkyl group, each having 1 to 5 C atoms. R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy or pentyloxy. The medium according to the invention preferably comprises triphenyls of the formulae T-1 to T-5 in an amount of 2-30% by weight, especially 3-20% by weight. Especially preferred are compounds of formulae T-1 to T-3, and more particularly compounds of formula T-1. Triphenyl is preferably used in the mixture according to the invention if the Δn value of the mixture is ≥ 0.1. Preferred mixtures contain 2-20% by weight of one or more triphenyl compounds selected from the group of compounds T-1 to T-5. The mixtures according to the invention preferably exhibit a very broad range of nematic phases, with a clearing point ≥ 70°C, preferably ≥ 75°C, especially ≥ 80°C; relatively high retention values, very favorable capacitance thresholds And at the same time at -20 ℃ and -30 ℃ very good low temperature stability, as well as very low rotational viscosity value and short response time. Furthermore, the mixtures according to the invention are distinguished by the fact that, in addition to the rotational viscosity γ ₁ improvement, a relatively high value of the elastic constant K ₃₃ for improving the response time is also observed. The use of compounds of formula I in LC mixtures, preferably with negative dielectric anisotropy, reduces the ratio of rotational viscosity _γ1 and elastic constant _Ki . The invention also relates to a process for the preparation of liquid-crystalline media according to the invention, wherein at least one compound of the formula I and at least one compound of the formula ST is mixed with at least one further liquid-crystalline compound, optionally with addition of one or more additives. Some preferred embodiments of the mixtures according to the invention are indicated below. The compounds of formula ST are preferably used in liquid crystal media in concentrations in the range from 0.0005% to 2% by weight, more preferably in the range from 0.001% to 1% by weight, particularly preferably in the range from 0.005% to 0.05% by weight. The total content of polymerizable or polymerizable components in the liquid-crystalline media according to the invention is preferably below 0.1% by weight, more preferably below 0.05% by weight and most preferably below 0.02% by weight (200 ppm). In a preferred embodiment, the liquid crystal medium comprises at least one compound of formula I, at least one compound of formula ST and one or more compounds of formula L. Optimally the liquid-crystalline medium comprises at least one compound of formula I, at least one compound of formula ST, one or more compounds of formula T and one or more compounds of formula L. Preferred compounds of formula L are selected from the following sub-formulas L-1 and L-2:

wherein _R independently of one another represents H, unsubstituted, CN or CF monosubstituted or at least monosubstituted alkyl or alkenyl having up to 15 C atoms, or at least monosubstituted halogen, and wherein, in addition, in one of these groups or more CH ₂ groups may be replaced by the following in such a way that the O atoms are not directly attached to each other: -O-, -S-,

, -C≡C-, -CF2O-, _-OCF2- , -OC- _O- or -O-CO-, and alkyl means an alkyl group having 1 to 6 C atoms. In the compounds of formula I, R ¹ and R ^{1 *} preferably each independently of one another represent a straight-chain alkoxy group, in particular OCH ₃ , n-C ₂ H ₅ O, n-OC ₃ H ₇ , n-OC ₄ H ₉ , n-OC _5H11 , n _{- OC6H13 ;} furthermore alkenyl, especially _CH2 = _CH2 , CH2CH= _CH2 , _{CH2CH = CHCH3} , _CH2CH = _{CHC2H5 ;} branched alkoxy, Especially _OC3H6CH ( _{CH3 ) 2 ;} and alkenyloxy, especially OCH= _CH2 , OCH2CH= _CH2 , _{OCH2CH = CHCH3} , _OCH2CH = _CHC2H5 . R ¹ and R ^{1 *} particularly preferably each independently of one another represent a straight-chain alkoxy group having 1 to 6 C atoms, especially methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy Oxygen. A ¹ and A ^{1 *} preferably represent 1,4-cyclohexane or 1,4-phenylene. Preferably parameters a and b are both 0, or alternatively a is 1 and b is 0. Optimally a=b=0. Both L ¹ and L ² in formula I preferably represent F. More preferably the compound of formula I is the compound of formula I-1 to formula I-20,

wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkane Oxy group and alkoxy group* each independently of each other represent a straight-chain alkoxy group having 1 to 6 C atoms, and L ¹ and L ² each independently of each other represent F or Cl. In the compounds of formulae I-1 to I-20, L ¹ and L ² preferably each independently of one another represent F or Cl, in particular L ¹ =L ² =F. Especially preferred are the compounds of formulae I-2 and I-6. In the compounds of formula I-2 and I-6, L ¹ =L ² =F is preferred. Very preferably the mixture according to the invention comprises at least one selected from the group consisting of formulae I-1A, I-2A, I-4A, I-6A, I-6B, I-11A, I-12-A, I-1 shown below Compounds of the group of compounds of -14A and I-16A:

Very particularly preferred mixtures comprise at least one compound selected from the group of compounds of the formula:

Compounds of formula I can be prepared, for example, as described in US 2015/0259602 A, US 9,512,102 B, US 2005/0258399 A or US 2004/124399 A. The medium according to the invention preferably comprises one, two, three, four or more, preferably one, two or three compounds of formula I. The compounds of the formula I are preferably used in the liquid-crystalline media in amounts of > 1% by weight, preferably > 3% by weight, based on the overall mixture. Particular preference is given to liquid-crystalline media comprising 1 to 40% by weight, very preferably 2 to 30% by weight, of one or more compounds of the formula I. Compounds of formula ST, particularly preferred wherein Pip is a compound of formula selected from groups of formula

or

wherein R ^a , R ^b , R ^c , and R ^d are independently straight or branched chain alkyl groups having 1 to 10 C atoms. Preferably, Z ¹ in the formula ST represents -CO-O-, -O-CO- or a single bond, very preferably -CO-O- or a single bond. Preferably, Z ² and Z ³ in formula ST represent -CO-O-, -O-CO- or a single bond, most preferably a single bond. Preferably, P in the formula ST is an acrylate group or a methacrylate group. Preferably, Sp in formula ST is a single bond. Preferably, R ^g in formula I is H. Preferably, A ³ in the formula ST represents an aromatic or heteroaromatic group having 6 to 24 ring atoms which may also contain a condensed ring and is optionally substituted with one or more groups L. Advantageously, A3 in ^formula ST represents benzene or naphthalene optionally substituted with one or more groups L. Preferably, A ¹ and A ² in formula ST represent those having 6 to 24 ring atoms, which may also contain condensed rings and, as the case may be, through one or more groups L or R-(A ³ -Z ³ ) _m2 - a substituted aromatic or heteroaromatic group, or A ¹ is a single bond. Preferably, A1 and A2 in ^formula ST represent benzene, cyclohexylene, naphthalene, phenanthrene or anthracene optionally substituted with ^one or more groups L or -(A3 ^- Z3 ⁾ _m2- , or A1 is ^a single bond. Preferably, -(A ² -Z ² -A ¹ ) _m1 - in formula ST represents benzene, biphenyl, paratriphenyl (1,4-diphenylbenzene), metatriphenyl (1,3 -diphenylbenzene), naphthylene, 2-phenyl-naphthylene, phenanthrene or anthracene, all of which are optionally substituted with one or more groups L. Very preferably, -(A ² -Z ² -A ¹ ) _m1 - represents biphenyl, paratriphenyl or metatriphenyl, all of which are optionally substituted with one or more groups L. Preferred groups -(A ² -Z ² -A ¹ ) _m1 - are selected from the formula

wherein L is as defined in formula ST or has one of the preferred meanings as described above and below, r is 0, 1, 2, 3 or 4, s is 0, 1, 2 or 3, and t is 0 , 1, or 2, and u is 0, 1, 2, 3, 4, or 5. Especially preferred are groups of formula A1, A2, A3, A4 and A5. Very particularly preferred mixtures according to the invention comprise one or more stabilizers selected from the following subformulae

wherein P, Sp, ^{Ra - d} , Z ¹ , L and R are as defined in formula ST or have one of the preferred meanings as described above and below, and ^Re is a group having 1 to 12 C atoms Alkyl, r is 0, 1, 2, 3, or 4, and s is 0, 1, 2, or 3. Preferably, Z ¹ in formula ST and ST-1 to ST-45 is -CO-O-, -O-CO- or a single bond, very preferably -CO-O- or a single bond. Preferably, P in formula ST and ST-1 to ST-45 is an acrylate group or a methacrylate group. Preferably, Sp in formula ST and ST-1 to ST-45 is a single bond. Preferably, R ^a , R ^b , R ^c and R ^d in formulae ST and ST-1 to ST-45 are methyl groups. Preferably, the structures in ST-1 to ST-45 are structures ST-1 and ST-23. More preferably, the compounds of formula ST and its sub-formulas ST-1 to ST-45 are independently selected from the following preferred embodiments, including any combination thereof: - These compounds contain exactly one polymerizable group (denoted as the group P), - when different from a single bond, Sp is selected from -(CH ₂ ) _a -O-, -(CH ₂ ) _a -CO-O-, -(CH ₂ ) _a - and -(CH ₂ ) _a -O-CO-, where a is 2, 3, 4, 5 or 6, and the O-atom or ^CO -group is attached to the next ring A2 or group Pip, respectively, if applicable, -R ^e is methyl, Ethyl, n-propyl, isopropyl, tert-butyl, n-butyl or n-pentyl, - m1 is 0, 1 or 2, - m2 is 0, 1 or 2, - Z ¹ represents -CO-O -, -O-CO- or single bond, preferably -CO-O-, - Z ² represents -CO-O-, -O-CO- or single bond, preferably single bond, - L represents F, Cl, CN or optionally fluorinated alkyl or alkoxy having ₁ to 6 C atoms, preferably F, Cl, CN, _CH3 , _OCH3 , OCF3, _OCF2H or _OCFH2 , optimal F One or more of , - L represents the group Pip, - r is 0 or 1, - s is 0, - t is 0, - u is 0, 1 or 2. Preferred embodiments of the liquid-crystalline media according to the invention are indicated below: a) liquid-crystalline media additionally comprising one or more compounds selected from the group of compounds of formula IIA, formula IIB and formula IIC,

wherein R ^2A , R ^2B and R ^2C each independently of one another represent H, an unsubstituted, CN or CF ₃ monosubstituted or at least monosubstituted alkyl or alkenyl group having up to 15 C atoms, and wherein, in addition, In these groups one or more _CH2 groups may be replaced by the following in such a way that the O atoms are not directly attached to each other: -O-, -S-,

, -C≡C-, -CF ₂ O-, -OCF ₂ -, -OC-O- or -O-CO-, L ^1-4 each independently represent F, Cl, CF ₃ or CHF ₂ , Z ² and Z ^{2 '} each independently represent a single bond, -CH ₂ CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, -CH ₂ O-, -OCH ₂ -, -COO -, -OCO-, -C ₂ F ₄ -, -CF=CF-, -CH=CHCH ₂ O-, -(O)C _v H _2v+1 means -OC _v H _2v+1 or -C _v H _2v+1 , p represents 0, 1 or 2, q represents 0 or 1, and v represents 1 to 6. In the compounds of formula IIA and IIB, Z ² may have the same or different meanings. In ^compounds of ^formula IIB, Z2 and Z2 ^' may have the same or different meanings. In the compounds of formula IIA, formula IIB and formula IIC, R ^2A , R ^2B and R ^2C each preferably represent an alkyl group having 1 to 6 C atoms, especially CH ₃ , C ₂ H ₅ , n-C ₃ H ₇ , normal C ₄ H ₉ , normal C ₅ H ₁₁ . In the compounds of formulae IIA and IIB, L ¹ , L ² , L ³ and L ⁴ preferably represent L ¹ =L ² =F, and L ³ =L ⁴ =F, in addition L ¹ =F, and L ² = Cl, L1 ⁼ Cl, and ^L2 =F, L3 ⁼ F, and ^L4 =Cl, L3 ⁼ Cl, and L4=F ^. Z ² and Z ^{2 ′} in formulae IIA and IIB preferably each independently of the other represent a single bond, additionally a -C ₂ H ₄ - bridge. If in Formula IIB, Z ² = -C ₂ H ₄ - or -CH ₂ O-, then Z ^{2 '} is preferably a single bond; or if Z ^{2 '} = -C ₂ H ₄ - or -CH ₂ O- , then Z ² is preferably a single bond. In the compounds of formula IIA and IIB, (O)C _v H _{2v + 1} preferably represents OC _v H _{2v + 1} . In compounds of formula IIC, (O)C _v H _{2v + 1} preferably represents C _v H _{2v + 1} . ^In the compound of ^formula IIC, L3 and L4 preferably each represent F. Preferred compounds of formula IIA, IIB and IIC are indicated below:

wherein alkyl and alkyl* each independently of each other represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl* each independently of each other represent a straight-chain alkenyl group having 2 to 6 C atoms. Particularly preferred mixtures according to the invention comprise one or more of formulae IIA-2, IIA-8, IIA-14, IIA-26, II-28, IIA-33, IIA-39, IIA-45, IIA-46, IIA Compounds of -47, IIA-50, IIB-2, IIB-11, IIB-16 and IIC-1. The proportion of the compound of formula IIA and/or formula IIB in the entire mixture is preferably at least 20% by weight. A particularly preferred medium of the present invention comprises at least one compound of formula IIC-1,

, wherein alkyl and alkyl* have the meanings indicated above, preferably in an amount >3% by weight, especially >5% by weight and especially preferably 5-25% by weight. b) liquid-crystalline media, which additionally comprise one or more compounds of the formula III,

wherein R ³¹ and R ³² each independently of one another represent a straight-chain alkyl, alkoxy, alkenyl, alkoxyalkyl or alkoxy group having up to 12 C atoms, and

express

or

Z ³ represents a single bond, -CH ₂ CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, - C ₂ F ₄ -, -C ₄ H ₈ -, -CF=CF-. Preferred compounds of formula III are indicated below:

wherein alkyl and alkyl* each independently of one another represent a straight-chain alkyl group having 1 to 6 C atoms. The medium according to the invention preferably comprises at least one compound of formula IIIa and/or formula IIIb. The proportion of the compound of formula III in the entire mixture is preferably at least 5% by weight. c) Liquid-crystalline media, which additionally comprise compounds of the formula

, the preferred total amount is ≥ 5 wt %, especially ≥ 10 wt %. Furthermore, preference is given to the mixture of the present invention comprising the following compound (abbreviation: CC-3-V1)

, the preferred amount is 2-15% by weight. Preferred mixtures comprise 5-60% by weight, preferably 10-55% by weight, especially 20-50% by weight of a compound of the formula (abbreviation: CC-3-V)

. In addition, preferred is a compound comprising the following formula (abbreviation: CC-3-V)

and a mixture of compounds of the following formula (abbreviation: CC-3-V1)

, and its preferred amount is 10-60% by weight. d) Liquid-crystalline media, which additionally comprise one or more tetracyclic compounds of the formula:

wherein each of R ^7-10 independently of each other has one of the meanings indicated for R ^2A in Solution 5, and w and x each independently of each other represent 1 to 6. Especially preferred are mixtures comprising at least one compound of formula V-9. e) liquid-crystalline media, which additionally comprise one or more compounds of the formulae Y-1 to Y-6,

wherein R ¹⁴ to R ¹⁹ each independently of each other represent an alkyl or alkoxy group having 1 to 6 C atoms; z and m each independently of each other represent 1 to 6; x represents 0, 1, 2 or 3. The medium according to the invention especially preferably comprises one or more compounds of the formulae Y-1 to Y-6, preferably in an amount of ≧5% by weight. f) liquid-crystalline media, which additionally comprise one or more fluorinated triphenyl groups of the formulae TF-1 to TF-21,

wherein R represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, and m=0, 1, 2, 3, 4, 5 or 6 and n represents 0, 1, 2, 3 or 4. R preferably represents methyl, ethyl, propyl, butyl, pentyl, hexyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy. The medium according to the invention preferably comprises triphenyls of the formulae TF-1 to TF-21 in an amount of 2-30% by weight, especially 5-20% by weight. Especially preferred are compounds of formulae TF-1, TF-2, TF-4, TF-20 and T-21. In these compounds, R preferably represents an alkyl group, furthermore an alkoxy group, each of which has 1 to 5 C atoms. In the compounds of formula TF-20, R preferably represents alkyl or alkenyl, especially alkyl. In the compound of formula TF-21, R preferably represents an alkyl group. Triphenyl is preferably used in the mixture according to the invention if the Δn value of the mixture is ≥ 0.1. Preferred mixtures contain 2-20% by weight of one or more triphenyl compounds selected from the group of compounds TF-1 to TF-21. g) liquid-crystalline media, which additionally comprise one or more biphenyl groups of the formulae PP-1 to PP-3,

wherein alkyl and alkyl* each independently of each other represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl* each independently of each other represent a straight-chain alkenyl group having 2 to 6 C atoms. The proportion of biphenyl groups of the formulae PP-1 to PP-3 in the entire mixture is preferably at least 3% by weight, in particular > 5% by weight. Among the compounds of formula PP-1 to PP-3, the compound of formula PP-2 is especially preferred. More preferably, the biphenyl group is

wherein alkyl* represents an alkyl group having 1 to 6 C atoms. The medium according to the invention especially preferably comprises one or more compounds of the formulae PP-1a and/or PP-2c. h) liquid-crystalline media comprising at least one compound of the formulae Z-1 to Z-7,

wherein R and alkyl have the meanings indicated above. i) liquid-crystalline media, which additionally comprise at least one compound of the formulae O-1 to O-18,

wherein R ¹ and R ² have the meanings indicated for R ^2A . R ¹ and R ² preferably each independently represent a straight-chain alkyl or alkenyl group. Preferred media comprise one or more of formulae O-1, O-3, O-4, O-6, O-7, O-10, O-11, O-12, O-14, O-15, O- Compounds of 16 and/or O-17. The mixtures according to the invention very particularly preferably comprise compounds of the formulae O-10, O-12, O-16 and/or O-17, especially in amounts of 5-50%. Preferred compounds of formula O-10 and O-17 are indicated below:

The medium according to the invention particularly preferably comprises a tricyclic compound of formula O-10a and/or formula O-10b and one or more bicyclic compounds of formula O-17a to O-17i. The total proportion of compounds of formula O-10a and/or O-10b and one or more compounds selected from bicyclic compounds of formulae O-17a to O-17i is 5% to 55%, very particularly preferably 15% to 40% %. Very particularly preferred mixtures comprise compounds O-10a and O-17a:

. Compounds O-10a and O-17a are preferably present in the mixture in a concentration of 15 to 50%, particularly preferably 25 to 45% and particularly preferably 25 to 35%, based on the entire mixture. Very particularly preferred mixtures additionally comprise one or more of compounds O-17b and O-17i:

Compounds O-17b and O-17i are preferably present in the mixture at a concentration of 5 to 20%, especially preferably 8 to 15%, based on the entire mixture of the two compounds. j) Preferred liquid-crystalline media according to the invention comprise one or more substances containing tetrahydronaphthyl or naphthyl units, such as compounds of formulae N-1 to N-5,

wherein R ^1N and R ^2N each independently of each other have the meaning indicated for R ^2A , preferably a straight-chain alkyl group, a straight-chain alkoxy group or a straight-chain alkenyl group, and Z ¹ and Z ² each independently of each other represent -C ₂ H ₄ -, -CH=CH-, -(CH ₂ ) ₄ -, -(CH ₂ ) ₃ O-, -O(CH ₂ ) ₃ -, -CH=CHCH ₂ CH ₂ -, -CH ₂ CH ₂ CH=CH-, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -C ₂ F ₄ -, -CF=CF-, -CF=CH-, -CH=CF-, -CF ₂ O-, -OCF ₂ -, -CH ₂ - or a single bond. k) Preferred mixtures comprise one or more compounds selected from the group consisting of difluorodibenzochroman compounds of formula BC, chroman of formula CR, fluorinated phenanthrenes of formula PH-1 and PH-2, formula BF-1 and BF-2 compounds of the group of fluorinated dibenzofurans,

wherein R ^B1 , R ^B2 , R ^CR1 , R ^CR2 , R ¹ , R ² each independently of one another have the meaning of R ^2A . c is 0, 1 or 2 and d represents 1 or 2. R ¹ and R ² preferably independently of each other represent an alkyl or alkoxy group having 1 to 6 C atoms. Compounds of formula BF-1 and BF-2 should not be equivalent to one or more compounds of formula I. The mixtures according to the invention preferably comprise compounds of the formulae BC, CR, PH-1, PH-2 and/or BF in amounts of 3 to 20% by weight, especially in amounts of 3 to 15% by weight. Especially preferred compounds of formula BC and CR are compounds BC-1 to BC-7 and CR-1 to CR-5,

wherein alkyl and alkyl* each independently of each other represent a straight-chain alkyl group having 1 to 6 C atoms, and alkenyl and alkenyl* each independently of each other represent a straight-chain alkenyl group having 2 to 6 C atoms. Very particularly preferred are mixtures comprising one, two or three compounds of the formulae BC-2, BF-1 and/or BF-2. l) A preferred mixture comprises one or more indan compounds of formula In,

wherein R ¹¹ , R ¹² , R ¹³ each independently of one another represent a straight-chain alkyl, alkoxy, alkoxyalkyl or alkenyl group having 1 to 6 C atoms, R ¹² and R ¹³ additionally represent halogen, and preferably F,

express

, i represents 0, 1 or 2. Preferred compounds of formula In are those of formula In-1 to In-16 indicated below:

. Especially preferred are compounds of formula In-1, formula In-2, formula In-3 and formula In-4. The compounds of the formula In and of the subformulas In-1 to In-16 are preferably used in the mixtures according to the invention in concentrations of ≧5% by weight, in particular 5-30% by weight and very particularly preferably 5-25% by weight. m) preferred mixtures additionally comprise one or more compounds of formulae LY-1 to LY-11,

wherein R, R ¹ and R ² each independently of each other have the meaning as indicated by R ^2A in Scheme 5, and the alkyl group represents an alkyl group having 1 to 6 C atoms. s means 1 or 2. -(O)Alkyl represents -O-alkyl or -alkyl, preferably -O-alkyl. Particularly preferred mixture concepts are indicated as follows: (The abbreviations used are set forth in Table A. n and m each independently of each other herein represent 1 to 15, preferably 1 to 6). The mixture according to the invention preferably comprises - one or more compounds of formula I, in which L ¹ =L ² =F and R ¹ =R ^{1 *} =alkoxy; - one or more compounds of formula ST in which m is 0 or 1 ; - one or more compounds of formula L, wherein n is 1; - one or more compounds of formula CPY-n-Om, in particular CPY-2-O2, CPY-3-O2 and/or CPY-5-O2, Based on the entire mixture, preferably in a concentration of >5%, in particular 10-30%, and - one or more formulae CY-n-Om, preferably CY-3-O2, CY-3-O4, CY- 5-O2 and/or CY-5-O4 compounds, based on the entire mixture, preferably in a concentration of >5%, in particular 5-25%, and/or - one or more formulae CCY-n-Om, preferably is a CCY-4-O2, CCY-3-O2, CCY-3-O3, CCY-3-O1 and/or CCY-5-O2 compound, preferably at a concentration of >5% based on the entire mixture, in particular 10-30%, the present invention further relates to an electro-optical display with active matrix addressing based on the ECB, VA, PS-VA, PA-VA, IPS, PS-IPS, FFS or PS-FFS effect, which contains The liquid crystal medium in one or more of the technical solutions is used as the dielectric. The liquid crystal medium of the present invention preferably has a nematic phase of ≤-20°C to ≥70°C, particularly preferably ≤-30°C to ≥80°C, very particularly preferably ≤-40°C to ≥90°C. The expression "having a nematic phase" means in this context that, on the one hand, no smectic phase and no crystallization are observed at low temperatures at the corresponding temperature, and, on the other hand, that the self-nematic phase still does not appear clear on heating. The studies at low temperatures were carried out in a flow viscometer at the corresponding temperature and checked by storage in a test cell with layer thickness corresponding to the electro-optical use for at least 100 hours. A medium is said to be stable at this temperature if its storage stability at -20°C in the corresponding test unit is 1000 h or longer. At -30°C and -40°C, the corresponding times were 500 h and 250 h, respectively. At high temperature, the clearing point is measured in a capillary using known methods. The liquid crystal mixture preferably has a nematic phase range of at least 60 K ^and a flow viscosity ν ₂₀ at 20° C. of at most 30 mm ² ·s ⁻¹ . The birefringence Δn value in the liquid crystal mixture is generally between 0.07 and 0.16, preferably between 0.08 and 0.13. The liquid crystal mixture according to the invention has a Δε of -0.5 to -8.0, especially -2.5 to -6.0, wherein Δε represents the dielectric anisotropy. The rotational viscosity g ₁ at 20° C. is preferably ≤150 mPa×s, specifically ≤120 mPa×s. The liquid-crystalline media according to the invention have relatively low threshold voltage (V ₀ ) values. It is preferably in the range of 1.7V to 3.0V, especially preferably ≤2.5V and very especially preferably ≤2.3V. For purposes of the present invention, unless expressly indicated otherwise, the term "threshold voltage" refers to the capacitance threshold (V ₀ ), also known as the Freedericks threshold. In addition, the liquid-crystalline media according to the invention have high voltage retention values in liquid-crystalline cells. In general, liquid crystal media with low addressing or threshold voltages exhibit lower voltage retention than liquid crystal media with higher addressing or threshold voltages, and vice versa. For the purposes of the present invention, the term "positive dielectric compound" refers to compounds with De > 1.5, the term "neutral dielectric compound" refers to those compounds with -1.5 £ De £ 1.5 and the term "negative dielectric compound" refers to compounds with De <-1.5 of those compounds. Herein, the dielectric anisotropy of a compound is determined by dissolving 10% of the compound in a liquid crystal host and determining the capacitance of the resulting mixture in at least one test cell, in each case the layer thickness of the test cell being 20 µm with vertical and homogeneous surface alignment at 1 kHz. The measurement voltage is typically 0.5 V to 1.0 V, but is always below the capacitance threshold for the individual liquid crystal mixtures studied. All temperature values indicated for the present invention are in °C. The mixtures according to the invention are suitable for IPS (Coplanar Switching) and UB-FFS (Fringe Field Switching) applications with negative De. It is additionally suitable for all VA-TFT applications, such as VAN, MVA, (S)-PVA, ASV, PSA (VA of Retaining Polymer) and PS-VA (VA of Stabilizing Polymer). Nematic liquid crystal mixtures in displays according to the invention generally comprise two components: A and B, which themselves consist of one or more individual compounds. Component A has a markedly negative dielectric anisotropy and imparts a nematic phase with a dielectric anisotropy of ≦−0.5. In addition to one or more compounds of formula I, it preferably comprises compounds of formula IIA, IIB and/or IIC, in addition one or more compounds of formula T. The proportion of component A is preferably 45 to 100%, especially 60 to 100%. For component A, one (or more) individual compounds having a value of De≦0.8 are preferably selected. It must be that the more negative this value is, the less the proportion A is in the whole mixture. Component B has a distinct nematic state, and at 20°C, the flow viscosity is not more than 30 mm ² ·s ^{- 1} , preferably not more than 25 mm ² ·s ^{- 1} . From the literature, a variety of suitable materials are known to those skilled in the art. Especially preferred are compounds of formula O-17. Particularly preferred individual compounds in component B are very low viscosity nematic liquid crystals having a flow viscosity of not more than 18 mm ² ·s ^{- 1} , preferably not more than 12 mm ² ·s ^{- 1} at 20°C. Component B is monotropic or tautomeric nematic, has no smectic phase and is capable of preventing the appearance of smectic phases in liquid crystal mixtures when lowered to very low temperatures. For example, if various high nematic materials are added to a smectic liquid crystal mixture, the nematic states of these materials can be compared via the degree of smectic phase suppression achieved. It is self-evident to those skilled in the art that the IPS, FFS or VA mixtures according to the invention may also comprise compounds such as H, N, O, Cl and F which have been isotopically substituted for the corresponding ones. The mixture according to the invention may additionally contain known additives such as stabilizers, antioxidants, UV absorbers, nanoparticles, microparticles and the like. The structure of the liquid crystal display according to the invention corresponds to the usual geometry. For example, preferred IPS displays contain an LC layer between two substrates with a planar orientation, wherein the two electrodes are disposed on only one of the two substrates and preferably have an interdigitated honeycomb structure. After a voltage is applied to the electrodes, an electric field is thus generated between them with a significant component parallel to the LC layer. This results in a realignment of the LC molecules in the layer plane. For negative IPS, the alignment direction of the alignment layer is preferably perpendicular to the interdigitated electrodes. So-called FFS ("Fringe Field Switching") displays have been reported (see in particular SH Jung et al., Jpn. J. Appl. Phys., Vol. 43, No. 3, 2004, 1028), which contain two electrodes, one of which is structured in a comb-like manner and the other is unstructured. In addition, FFS displays have been disclosed (see SH Lee et al, Appl. Phys. Lett. 73(20), 1998, 2882-2883 and SH Lee et al, Liquid Crystals 39(9), 2012, 1141-1148), which Has a similar electrode design and layer thickness to FFS displays, but includes an LC dielectric layer with negative dielectric anisotropy instead of an LC dielectric layer with positive dielectric anisotropy. The following meanings apply above and below: Unless otherwise stated, the term "polymerizable compound" as used herein shall be understood to mean a polymerizable monomeric compound. The term "spacer" or simply "spacer", also referred to as "Sp", above and below, is known to those skilled in the art and described in the literature, see for example Pure Appl. Chem. 73(5), 888 (2001) and in C. Tschierske, G. Pelzl, S. Diele, Angew. Chem. (2004), 116, 6340-6368. Unless otherwise indicated, the terms "spacer group" or "spacer" above and below refer to a flexible group in a polymerizable mesogen compound that connects the mesogen group and the polymerizable group to each other. While mesogen groups generally contain rings, spacer groups are generally acyclic systems, ie in the form of chains, where the chains may also be branched. The term chain system is used, for example, for alkylene. Substitutions such as by -O- or -COO- are typically included on and in the chain. In functional terms, a spacer (spacer group) is a linking group between functional moieties of a molecule that contributes to some steric flexibility between these moieties. In a preferred embodiment, the spacer represents an alkylene group (eg _- ( _CH2 ) _n- and n=1 to 10) or an alkyleneoxy group, which preferably has 2 to 5 carbon atoms. The term "halogen" means fluorine, chlorine or bromine, preferably fluorine or chlorine and especially fluorine. The term halogenated is used analogously. Throughout the patent application, the 1,4-cyclohexylene and 1,4-phenylene rings are depicted as follows:

;

. The 1,4-substituted cyclohexylene ring is a trans-1,4-cyclohexylene ring. The following examples are intended to illustrate the invention without limiting it. In the above and below, percentage data are expressed as weight percent; all temperatures are expressed in degrees Celsius. Throughout the patent application and working examples, the structure of the liquid crystal compounds is indicated by means of abbreviations. Conversions to formulae were performed according to Tables 1-3 unless otherwise indicated. All groups _{CnH2n + 1} , _{CmH2m + 1} and _{Cm'H2m ' + 1} or _{CnH2n and CmH2m are in} each case _n , _m , _{m '} or z respectively A straight-chain alkyl or alkylene group with one C atom. n, m, m', z each independently represent 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, preferably 1, 2, 3, 4, 5 or 6 . In Table 1, the ring elements of the respective compounds are coded, in Table 2, the bridging members are listed, and in Table 3, the meaning of the symbols for the left or right side chains of the compounds is indicated. Table 1 : Ring Elements

Table 2 : Bridge Members

Table 3 : Sidechains

In addition to one or more compounds of formula I, the mixtures according to the invention preferably comprise one or more of the compounds mentioned in Table A below. Table A uses the following abbreviations: (n, m, m', z: each independently of one another is 1, 2, 3, 4, 5 or 6; (O)C _m H _2m+1 means OC _m H _2m+1 or C _m H _2m+1 )

The liquid crystal mixtures used according to the invention can be prepared in a manner known per se. In general, it is preferable to dissolve the desired amount of the component, which is used in a smaller amount, in the component constituting the main component at a high temperature. It is also possible to mix the solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and it is possible to remove the solvent again, for example by distillation after thorough mixing. With the aid of suitable additives, the liquid crystal phase according to the present invention can be modified so that it can be used in any type of displays disclosed so far (eg ECB, VAN, IPS, GH or ASM-VA LCD). The dielectric may also contain other additives known to those skilled in the art and described in the literature, such as UV absorbers, antioxidants, nanoparticles and free radical scavengers. For example, 0-15% of pleochroic dyes, stabilizers such as phenols, HALS (Hindered Amine Light Stabilizers) or chiral dopants can be added. Stabilizers suitable for the mixtures according to the invention are in particular those listed in Table C. For example, 0-15% of pleochroic dyes can be added, and conductive salts can be added, preferably 4-hexyloxybenzoate ethyldimethyldodecylammonium, tetraphenyl borohydride tetrabutyl Complex salts of base ammonium or crown ethers (see eg Haller et al., Mol. Cryst. Liq. Cryst., Vol. 24, pp. 249-258 (1973)) to improve conductivity, or substances can be added to improve conductivity Dielectric anisotropy, viscosity and/or orientation of the nematic phase. Substances of this type are described, for example, in DE-A 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53 728. Table B Table B indicates possible dopants that can be added to the mixtures according to the invention. If the mixture contains a dopant, it is added in an amount of 0.01 to 4% by weight, preferably 0.01 to 3% by weight.

The mixtures according to the invention comprise at least one stabilizer from Table C given below. Table C indicates below which stabilizers may be added, for example, to the mixtures according to the invention in amounts of 0 to 10% by weight, preferably 0.001 to 5% by weight, especially 0.001 to 1% by weight.

n = 1, 2, 4, 5, 6 or 7

n = 1, 2, 4, 5, 6 or 7

n = 2, 3, 4, 5 or 6

Working Examples The following examples are intended to illustrate the invention without limiting it. In the examples, mp represents the melting point (in degrees Celsius) of the liquid crystal substance and C represents the clearing point (in degrees Celsius) of the liquid crystal substance; the boiling temperature is represented by mp. In addition: C represents crystalline solid state, S represents smectic phase (index represents phase type), N represents nematic state, Ch represents cholesteric liquid crystal phase, I represents isotropic phase, and T _g represents glass transition temperature. The number between the two symbols indicates the transformation temperature in degrees Celsius an. The host mixture used for the determination of the optical anisotropy Δn of the compounds of formula I was the commercially available mixture ZLI-4792 (Merck KGaA). The dielectric anisotropy Δε was determined using the commercially available mixture ZLI-2857. Physical data for the compounds under investigation were obtained from the change in the dielectric constant of the host mixture after addition of the compounds under investigation and extrapolation to 100% of the compounds used. In general, depending on solubility, 10% of the compound to be investigated is dissolved in the host mixture. Unless otherwise indicated, parts or percentage data refer to parts or percentages by weight. Above and below: V _o denotes capacitance threshold voltage [V] at 20°C, _ne denotes extraordinary refractive index at 20 _° C and 589 nm, no denotes ordinary refractive index at 20°C and 589 nm , Dn represents the optical anisotropy at 20°C and 589 nm, e _^ represents the dielectric permittivity perpendicular to the director at 20°C and 1 kHz, e _÷÷ represents the dielectric permittivity at 20°C and 1 kHz, Dielectric permittivity parallel to director, De denotes dielectric anisotropy at 20°C and 1 kHz, cl.p., T(N,I) denotes clearing point [°C], g ₁ denotes at 20 Rotational viscosity measured at ℃ [mPa∙s], which is determined by the rotational method in a magnetic field, K ₁ represents the elastic constant, "tilted" deformation at 20 ℃ [pN], K ₂ represents the elastic constant, at "Twisting" deformation at ₂₀ °C [pN], K3 denotes elastic constant, "bending" deformation at 20°C [pN], LTS denotes low temperature stability (nematic phase) measured in the test cell. Unless expressly stated otherwise, all indicated values in this application are for temperatures such as melting point T(C,N), transition from smectic (S) to nematic (N) phase T(S,N) and clarification points T(N,I) are all indicated in degrees Celsius (°C). Mp means melting point, cl.p. = clearing point. Furthermore, Tg = glassy state, C = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The numbers between these symbols indicate the transfer temperature. For purposes of the present invention, unless expressly indicated otherwise, the term "threshold voltage" refers to the capacitance threshold value (V ₀ ), also known as the Frederick threshold value. In an example, an optical threshold value may also be indicated for 10% relative contrast (V ₁₀ ), as is commonly used. The display used to measure the capacitance threshold voltage consists of two plane-parallel glass outer plates with a distance of 20 µm, each of which has an electrode layer on the inner side and a friction-free polyimide alignment layer on the top, which realizes Vertical edge alignment of liquid crystal molecules. The display or test cell for measuring the tilt angle consists of two plane-parallel glass outer plates with a distance of 4 µm, each with an electrode layer on the inner side and a polyimide alignment layer on the top, two of which are polymerized. The imide layers are rubbed antiparallel to each other and achieve vertical edge alignment of the liquid crystal molecules. The polymerizable compound is polymerized in a display or test cell by irradiating it with UVA light of defined intensity (usually 365 nm) for a predetermined time while a voltage is applied to the display (usually 10 V to 30 V AC, 1 kHz). In the examples, unless otherwise indicated, a 50 mW/ ^cm2 mercury vapor lamp was used, and the intensity was measured using a standard UV meter (Made Ushio UNI meter) equipped with a 365 nm bandpass filter. The tilt angle was determined from a rotating crystal experiment (Autronic-Melchers TBA-105). A low value here (ie a large deviation from an angle of 90°) corresponds to a large tilt. The VHR values were measured as follows: The liquid crystal medium was introduced into a TN-VHR test cell (alignment layer as indicated). HR values were determined before and after UV exposure at 1 V, 60 Hz, 64 μs pulses after 5 min at 60° C. (measuring instrument: Autronic-Melchers VHRM-105). To study low temperature stability, also known as "LTS", i.e. the stability of the LC mixture spontaneously crystallizing out of individual components at low temperatures, bottles containing 1 g of the LC/RM mixture were stored at -10°C and checked regularly Whether the mixture crystallized out. The so-called "HTP" means the optically active or helical twisting force (in μm) on chiral species in LC media. Unless otherwise indicated, HTP was measured with a commercially available nematic LC host mixture MLD-6260 (Merck KGaA) at a temperature of 20°C. Unless expressly stated otherwise, all concentrations in this application are indicated in weight percent and refer to the entire corresponding mixture (solvent free) comprising all solid or liquid crystal components. Unless expressly indicated otherwise, all physical properties are determined according to "Merck Liquid Crystals, Physical Properties of Liquid Crystals", Status November 1997, Merck KGaA, Germany and apply to a temperature of 20°C. The following polymerizable stabilizers (polymerizable piperidine derivatives) were used:

Source: Santa Cruz Inc. (CAS 31582-45-3)

Synthesis Examples of Additives Exemplary compounds of formula I are synthesized as follows or according to WO 2016/116119 A1 (Examples). Synthesis Example Compound STF - 2 can be prepared as follows.

4-HydroxyTEMPO (8.00 g, 45.5 mmol) and 4-(dimethylamino)pyridine (0.30 g, 2.46 mmol) were added to 100 ml of DCM. After cooling to 2°C, triethylamine (25.00 ml, 180.35 mmol) was added to the above solution, followed by 3-bromo-propionyl chloride (6.00 ml, 50.6 mmol) dropwise to 50 ml DCM. After the addition was complete, the reaction mixture was allowed to warm to room temperature. After completion of the conversion indicated by TLC, aqueous ammonium chloride was added. The aqueous phase was extracted with DCM. The organic phases were combined and dried over anhydrous sodium sulfate and filtered. After removing the solvent in vacuo, the solid residue was purified by silica gel column chromatography using DCM/methyl tertiary butyl ether (MTBE) 95:5 as eluent and further recrystallized from heptane/MTBE to give STF - 2 as red crystals (mp102°C). The following examples of mixtures with negative dielectric anisotropy are particularly suitable for liquid crystal displays with at least one planar alignment layer, such as IPS and FFS displays, especially UB-FFS (=ultra-bright FFS), and for VA displays. Mixture Examples Example M1 Following Liquid Crystal Mixtures

Additionally included 0.01% of STF-1 (Example 1) and STF-2 (Example 2). The mixture of Example M1 containing the stabilizer was distinguished by excellent reliability and high VHR values after stress testing. Comparative Example A A comparative liquid crystal mixture (Example A) was prepared according to Example M1 but omitting the stabilizer STF-1/2. VHR Measurements : Effect of Polymerizable Piperidine Derivatives under Backlight Loading Test cells consisting of glass plates with rubbed polyimide surfaces were filled with the media of previous example M1 and comparative example A. The voltage holding ratio (VHR) of the test cell was measured before and after full light loading (120 min). The illumination light is equivalent to 500 h of a typical white CCFL backlight for a display. Table 1: Results of rubbing polyimide (OPTMER® AL16301, JSR Corp.):

*BL = Backlight Load Test; 120 h accelerated LED-based backlight

Claims (14)

A liquid-crystalline medium, wherein it comprises at least one compound of the formula I,

wherein R ¹ and R ^1* each independently of one another represent H, an alkyl group having from 1 to 15 C atoms or an alkoxy group, wherein, in addition, one or more CH ₂ groups of these groups can each independently of one another independently replaced by the following in such a way that the O atoms are not directly connected to each other: -C≡C-, -CF2O-, _-OCF2- , -CH= _CH- ,

,

, -O-, -CO-O-, -O-CO-, and wherein, in addition, one or more H atoms may be replaced by halogen, A ¹ and A ^1* each independently of one another represent a) 1,4-extended Cyclohexenyl or 1,4-cyclohexylene, in which one or two non-adjacent _CH2 groups can be replaced by -O- or -S-, b) 1,4-phenylene, in which one or two The CH group can be replaced by N, c) from piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]denooctyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6 - Groups of diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and perylene-2,7-diyl, wherein group a), b) and c) may be mono- or polysubstituted by halogen atoms, and Z ¹ and Z ^1* each independently represent -CO-O-, -O-CO-, -CF ₂ O-, -OCF ₂ -, - CH ₂ O-, -OCH ₂ -, -CH ₂ -, -CH ₂ CH ₂ -, -(CH ₂ ) ₄ -, -CH=CH-CH ₂ O-, -C ₂ F ₄ -, -CH ₂ CF ₂ -, -CF ₂ CH ₂ -, -CF=CF-, -CH=CF-, -CF=CH-, -CH=CH-, -C≡C- or single bond, a and b represent independently 0 or 1, X represents -S-, and L ¹ and L ² each independently of one another represent F, Cl, CF ₃ or CHF ₂ , and at least one compound of the formula ST below, or a polymer comprising the polymerized form thereof, P- Sp-(A ² -Z ² -A ¹ ) _m1 -Z ¹ -Pip ST wherein the individual groups independently of one another and at each occurrence the same or different have the following meanings: Pip is selected from groups of the formula

R ^g H or straight or branched chain alkyl or alkoxyalkyl having 1 to 10 C atoms, or benzyl, R ^a , R ^b , R ^c , R ^d having 1 to 10 C atoms Linear or branched alkyl, P vinyloxy, acrylate, methacrylate, fluoroacrylate, chloroacrylate, oxetanyl or epoxy, Sp spacer or Single bond, A ¹ , A ² have 4 to 30 alicyclic groups, heterocyclic groups, aromatic groups or heteroaromatic groups of ring atoms, which may also contain condensed rings and are optionally connected to one or more groups L Or R-(A ³ -Z ³ ) _{m 2} -substituted, and one of A ¹ and A ² may also represent a single bond, A ³ has 4 to 30 ring atoms of alicyclic, heterocyclic, aromatic or heteroaromatic groups, which may also contain fused rings and are optionally substituted with one or more groups L, Z ¹ -O-, -S-, -CO-, -CO-O-, -O-CO -, -O-CO-O-, -OCH ₂ -, -CH ₂ O-, -SCH ₂ -, -CH ₂ S-, -CF ₂ O-, -OCF ₂ -, -CF ₂ S-, - SCF ₂ -, -(CH ₂ ) _n -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ -, -(CF ₂ ) _n -, -CH=CH-, -CF=CF-, -CH=CF -, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH ₂ -CH ₂ -CO-O-, -O-CO -CH ₂ -CH ₂ -, -CR ⁰⁰ R ⁰⁰⁰ - or single bond, the limitation is that if m1 is 0, then Z ¹ is a single bond, Z ² , Z ³ -O-, -S-, -CO -, -CO-O-, -O-CO-, -O-CO- _O- , _-OCH2- , _-CH2O- , _-SCH2- , _-CH2S- , -CF2O-, -OCF ₂ -, -CF ₂ S-, -SCF ₂ -, -(CH ₂ ) _n -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ -, -(CF ₂ ) _n -, -CH=CH -, -CF=CF-, -CH=CF-, -CF=CH-, -C≡C-, -CH=CH-CO-O-, -O-CO-CH=CH-, -CH ₂ - CH ₂ -CO-O-, -O-CO-CH ₂ -CH ₂ -, -CR ⁰⁰ R ⁰⁰⁰ - or single bond, R ⁰⁰ , R ⁰⁰⁰ H or alkyl with 1 to 12 C atoms, R P -Sp-, H, F, Cl, CN, or straight-chain, branched-chain, or cycloalkyl having 1 to 25 C atoms, wherein one or more non-adjacent _CH2 -groups optionally end with O - and/or S- atoms are not directly connected to each other via -O-, -S-, -CO -, -CO-O-, -O-CO-, -O-CO-O- are replaced, and one or more of the H atoms are each optionally replaced by F, Cl or P-Sp- or the group Pip, L P-Sp-, F, Cl, CN or straight-chain, branched-chain alkyl or cycloalkyl having 1 to 25 C atoms, wherein one or more non-adjacent CH2- groups are optionally _O- and /or S- atoms are replaced by -O-, -S-, -CO-, -CO-O-, -O-CO-, -O-CO-O- in such a way that they are not directly connected to each other, and one or more of them Each of the H atoms is optionally replaced by F, Cl or P-Sp- or a group selected from formulae 1, 2 and 3, m1 0, 1, 2, 3 or 4, m2 0, 1, 2, 3 or 4 , and n 1, 2, 3, or 4. A liquid-crystalline medium as claimed in claim 1, wherein the medium comprises at least one compound of formula I-1 to formula I-20,

wherein alkyl and alkyl* each independently represent a straight-chain alkyl group having 1 to 6 C atoms, alkenyl and alkenyl* each independently represent a straight-chain alkenyl group having 2 to 6 C atoms, alkane Oxy group and alkoxy group* each independently of each other represent a straight-chain alkoxy group having 1 to 6 C atoms, and L ¹ and L ² each independently of each other represent F, Cl, CF ₃ or CHF ₂ . The liquid crystal medium of claim 1, wherein L ¹ and L ² in the formula I each represent F. The liquid-crystalline medium of claim 1, wherein it comprises one or more compounds selected from the group consisting of formulae T and L

wherein L ¹ and L ² are independently H or F, wherein at least one of L ¹ and L ² is F, and L ³ and L ⁴ are independently H or F, wherein at least one of L ³ and L ⁴ For F, R each independently of one another represents H, an alkyl group having 1 to 15 C atoms or an alkoxy group, wherein, in addition, one or more CH ₂ groups of these groups can each independently of one another be represented by The way in which the O atoms are not directly connected to each other is replaced by the following: -C≡C-, -CF2O-, _-OCF2- , -CH= _CH- ,

,

, -O-, -CO-O-, -O-CO-, and wherein in addition, one or more H atoms may be replaced by halogen, alkyl has a straight or branched chain of 1 to 6 C atoms, n 0 or 1, and (O) is -O- or a single bond. A liquid-crystalline medium as claimed in any one of claims 1 to 4, wherein it additionally comprises one or more compounds selected from the group of compounds of the formulae IIA, IIB and IIC,

wherein R ^2A , R ^2B and R ^2C each independently of one another represent H, an unsubstituted, CN or CF ₃ monosubstituted or at least monosubstituted alkyl or alkenyl group having up to 15 C atoms, and wherein, in addition, In these groups one or more _CH2 groups may be replaced by the following in such a way that the O atoms are not directly attached to each other: -O-, -S-,

, -C≡C-, -CF ₂ O-, -OCF ₂ -, -OC-O- or -O-CO-, L ^1-4 independently represent F or Cl, Z ² and Z ^2' each independently refer independently of each other to single bonds, _-CH2CH2- , -CH= _CH- , _-CF2O- , _-OCF2- , _-CH2O- , _-OCH2- , -COO-, -OCO- , -C ₂ F ₄ -, -CF=CF-, -CH=CHCH ₂ O-, -(O)C _v H _2v+1 means -OC _v H _2v+1 or -C _v H _2v+1 , p represents 0, 1 or 2, q represents 0 or 1, and v represents 1 to 6. The liquid-crystalline medium of any one of claims 1 to 4, wherein the medium additionally comprises one or more Compounds of formula L as defined in claim 4. A liquid-crystalline medium as claimed in any one of claims 1 to 4, wherein the medium comprises one or more compounds of formula T-1,

wherein R represents a straight-chain alkyl or alkoxy group having 1 to 6 C atoms, and m is 0, 1, 2, 3, 4, 5 or 6. A liquid-crystalline medium as claimed in any one of claims 1 to 4, wherein the medium additionally comprises one or more compounds of the formulae O-1 to O-18:

wherein R ¹ and R ² each independently of one another represent H, an alkyl group having 1 to 15 C atoms or an alkoxy group, wherein, in addition, one or more CH ₂ groups of these groups may each independently of one another The ground is replaced by the following in such a way that the O atoms are not directly connected to each other: -C≡C-, -CF ₂ O-, -OCF ₂ -, -CH=CH-,

,

, -O-, -CO-O-, -O-CO-, and wherein in addition, one or more H atoms may be replaced by halogen. The liquid-crystalline medium of any one of claims 1 to 4, wherein the medium additionally comprises one or more compounds selected from the group of compounds of the formulae O-10a to O-17i:

A liquid-crystalline medium as claimed in any one of claims 1 to 4, wherein the medium additionally comprises one or more compounds of the formulae O-10a to O-17a:

The liquid-crystalline medium as claimed in any one of claims 1 to 4, wherein the proportion of the compound of formula I in the entire medium is from 1% by weight to 40% by weight. A use of a liquid crystal medium as claimed in any one of claims 1 to 11 in an electro-optical display. An electro-optical display with active matrix addressing, wherein it contains a liquid crystal medium as in any one of claims 1 to 11 as dielectric. An electro-optic display as claimed in claim 13, wherein it is a negative IPS, U-IPS or UB-FFS display.