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US-12624290-B2 - Method for reducing white flicker

US12624290B2US 12624290 B2US12624290 B2US 12624290B2US-12624290-B2

Abstract

A method for reducing white flicker by bringing together into a composition one or more compounds of formula G with one or more compounds of formula B and/or C to form a liquid crystal (LC) medium having negative dielectric anisotropy, wherein the reduction of white flicker is achieved compared to an otherwise identical composition, but which does not include either (i) a compound of formula G or (ii) a compound of formula B and/or C.

Inventors

  • Harald Hirschmann
  • Ewgenij Wakaresko

Assignees

  • MERCK PATENT GMBH

Dates

Publication Date
20260512
Application Date
20240904
Priority Date
20200107

Claims (18)

  1. 1 . A method for reducing white flicker induced by affecting a flexoelectric effect of a liquid crystal (LC) medium, wherein said LC medium has negative dielectric anisotropy, said method comprising adding to said LC medium one or more compounds of formula G and one or more compounds of formula B and/or C, and applying a voltage to the resultant LC medium containing the one or more compounds of formula G and the one or more compounds of formula B and/or C, leading to an effect that reduces white flicker, wherein the reduction of white flicker is achieved in said resultant LC medium containing the one or more compounds of formula G and the one or more compounds of formula B and/or C compared to the LC medium to which a compound of formula G has not been added: in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meanings: denotes R 0 , R 1 , R 2 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, L 1 , L 2 denote F or Cl, X 0 denotes F, Cl, CN, SF 5 , SCN, NCS, or a halogenated alkyl radical or a halogenated alkoxy radical having 1 to 6 C atoms, or a halogenated alkenyl radical or a halogenated alkenyloxy radical having 2 to 6 C atoms, Y 1 denotes O, S or CH 2 O, and Z 0 denotes a single bond, —C 2 H 4 —, —CH 2 O—, —CF 2 O—, or —CH═CH—; and wherein said resultant LC medium is not the following medium CCP-3-1 3.0% CCP-V-1 2.5% CLY-3-O2 8.0% CLY-4-O2 8.0% CLY-5-O2 7.0% CPY-3-O2 6.5% B(S)-2O-O4 4.0% B(S)-2O-O5 6.0% B(S)-2O-O6 3.0% CC-3-V1 8.0% CC-4-V1 20.0% CC-3-V 6.0% Y-4O-O4 10.0% CCG-V-F 8.0% Σ 100.0%.
  2. 2 . A method for reducing white flicker induced by affecting a flexoelectric effect of a liquid crystal (LC) medium, wherein said LC medium has negative dielectric anisotropy, wherein said LC medium contains one or more compounds of formula B and/or C, said method comprising adding to said LC medium one or more compounds of formula G, and applying a voltage to the resultant LC medium containing the one or more compounds of formula G, leading to an effect that reduces white flicker, wherein the reduction of white flicker is achieved in said resultant LC medium containing the one or more compounds of formula G compared to said LC medium to which a compound of formula G has not been added: in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meanings: denotes R 0 , R 1 , R 2 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, L 1 , L 2 denote F or Cl, X 0 denotes F, Cl, CN, SF 5 , SCN, NCS, or a halogenated alkyl radical or a halogenated alkoxy radical having 1 to 6 C atoms, or a halogenated alkenyl radical or a halogenated alkenyloxy radical having 2 to 6 C atoms, Y 1 denotes O, S or CH 2 O, and Z 0 denotes a single bond, —C 2 H 4 —, —CH 2 O—, —CF 2 O—, or —CH═CH—; and wherein said resultant LC medium is not the following medium CCP-3-1 3.0% CCP-V-1 2.5% CLY-3-O2 8.0% CLY-4-O2 8.0% CLY-5-O2 7.0% CPY-3-O2 6.5% B(S)-2O-O4 4.0% B(S)-2O-O5 6.0% B(S)-2O-O6 3.0% CC-3-V1 8.0% CC-4-V1 20.0% CC-3-V 6.0% Y-4O-O4 10.0% CCG-V-F 8.0% Σ 100.0%.
  3. 3 . The method according to claim 1 , wherein the one or more compounds of formula B are selected from the following formulae wherein R 1 and R 2 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen.
  4. 4 . The method according to claim 1 , wherein the one or more compounds of formula C are selected from the following formulae wherein R 1 and R 2 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen.
  5. 5 . The method according to claim 1 , wherein the one or more compounds of formula G are selected from the following formulae wherein R 0 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen.
  6. 6 . The method according to claim 1 , wherein the LC medium additionally comprises one or more compounds selected from formulae CY and PY: in which the individual radicals have the following meanings: a denotes 1 or 2, b denotes 0 or 1, denotes R 1 and R 2 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH 2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, Z x and Z y each, independently of one another, denotes —CH═CH—, —CH 2 O—, —OCH 2 —, —CF 2 O—, —OCF 2 —, —O—, —CH 2 —, —CH 2 CH 2 — or a single bond, L 1-4 each, independently of one another, denote F, Cl, OCF 3 , CF 3 , CH 3 , CH 2 F, or CHF 2 , and L 5 denotes H or CH 3 .
  7. 7 . The method according to claim 1 , wherein the LC medium additionally comprises one or more compounds selected from formula ZK and one or more compounds selected from formula DK in which the individual radicals on each occurrence, identically or differently, have the following meanings: denotes denotes denotes and R 3 and R 4 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH 2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, Z y denotes —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —COO—, —OCO—, —C 2 F 4 —, —CF═CF— or a single bond, R 5 and R 6 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH 2 groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, and e denotes 1 or 2.
  8. 8 . The method according to claim 1 , wherein the LC medium additionally comprises one or more compounds selected from the following formulae in which alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms, and alkenyl and alkenyl* each, independently of one another, denote a straight-chain alkenyl radical having 2-6° C. atoms.
  9. 9 . The method according to claim 1 , wherein the LC medium additionally comprises s one or more compounds of the following formula in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meaning R 1 , R 2 each, independently of one another, denote alkyl having 1 to 12 C atoms, in which one or two non-adjacent CH 2 groups may be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a way that O atoms are not linked directly to one another, and L T1 -L T6 denote H, F or Cl, with at least one of L T1 to L T6 being F or Cl.
  10. 10 . The method according to claim 1 , wherein the LC medium comprises one or more compounds of formula C1 wherein R 1 and R 2 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen.
  11. 11 . The method according to claim 1 , wherein the LC medium comprises one or more compounds of formula B in which the individual radicals, on each occurrence identically or differently, and each, independently of one another, have the following meanings: R 1 , R 2 denote a straight chain alkyl or alkoxy radical having 1 to 15 C atoms or a branched alkyl or alkoxy radical having 3 to 15 C atoms, in which one or more CH 2 groups may each be replaced, independently of one another, by —C≡C—, —CF 2 O—, —OCF 2 —, —CH═CH—, —O—, —CO—O— or —O—CO— in such a way that O atoms are not linked directly to one another, and in which one or more H atoms may be replaced by halogen, L 1 , L 2 denote F or Cl, and Y 1 denotes O, S or CH 2 O.
  12. 12 . The method according to claim 1 , wherein the resultant LC medium contains 2 to 20% by weight the one or more compounds of formula G.
  13. 13 . The method according to claim 1 , wherein the resultant LC medium contains 4 to 10% by weight the one or more compounds of formula G.
  14. 14 . The method according to claim 1 , wherein the resultant LC medium contains 2 to 20% by weight the one or more compounds of formula B.
  15. 15 . The method according to claim 1 , wherein the resultant LC medium contains 7 to 14% by weight the one or more compounds of formula B.
  16. 16 . The method according to claim 1 , wherein the resultant LC medium contains 2 to 20% by weight the one or more compounds of formula C.
  17. 17 . The method according to claim 1 , wherein the resultant LC medium contains 8 to 12% by weight the one or more compounds of formula C.
  18. 18 . The method according to claim 1 , wherein the resultant LC medium contains 4 to 10% by weight the one or more compounds of formula G and 7 to 14% by weight the one or more compounds of formula B and 8 to 12% by weight the one or more compounds of formula C.

Description

This application is a divisional of U.S. application Ser. No. 17/142,835, filed Jan. 6, 2021, which issued as U.S. Pat. No. 12,305,103 on May 20, 2025, and which claims priority to EP 20150435.4 filed Jan. 7, 2020. The invention relates to a liquid-crystalline medium, in particular based on a mixture of polar compounds, and to the use thereof for an active-matrix display, in particular based on the VA, SA-VA, IPS, PS—IPS, FFS, PS—FFS, UB—FFS or PS—UB—FFS effect. Media of this type can be used, in particular, for electro-optical displays having active-matrix addressing based on the ECB effect and for IPS (in-plane switching) displays or FFS (fringe field switching) displays. The principle of electrically controlled birefringence, the ECB effect or also DAP (deformation of aligned phases) effect, was described for the first time in 1971 (M. F. Schieckel 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. Labrunie and J. Robert (J. Appl. Phys. 44 (1973), 4869). The 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) showed that liquid-crystalline phases must have high values for the ratio of the elastic constants K3/K1, high values for the optical anisotropy Δn and values for the dielectric anisotropy of Δε≤−0.5 in order to be suitable for use in high-information display elements based on the ECB effect. Electro-optical display elements based on the ECB effect have a homeotropic edge alignment (VA technology=vertically aligned). Dielectrically negative liquid-crystal media can also be used in displays which use the so-called IPS or FFS effect. Displays which use the ECB effect, as so-called VAN (vertically aligned nematic) displays, for example in the MVA (multi-domain vertical alignment, for example: 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 to 9, and Liu, C. T. et al., paper 15.1: “A 46-inch TFT-LCD HDTV Technology . . . ”, SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 750 to 753), PVA (patterned vertical alignment, for example: 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, Book II, pp. 760 to 763), ASV (advanced super view, for example: 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 to 757) modes, have established themselves as one of the three more recent types of liquid-crystal display that are currently the most important, in particular for television applications, besides IPS (in-plane switching) displays (for example: Yeo, S. D., paper 15.3: “An LC Display for the TV Application”, SID 2004 International Symposium, Digest of Technical Papers, XXXV, Book II, pp. 758 & 759) and the long-known TN (twisted nematic) displays. The technologies are compared in general form, for example, 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 times of modern ECB displays have already been significantly improved by addressing methods with overdrive, 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 to 109, the achievement of video-compatible response times, in particular on switching of grey shades, is still a problem which has not yet been satisfactorily solved. Industrial application of this effect in electro-optical display elements requires LC phases, which have to satisfy a multiplicity of requirements. Particularly important here are chemical resistance to moisture, air and physical influences, such as heat, infrared, visible and ultraviolet radiation and direct and alternating electric fields. Furthermore, industrially usable LC phases are required to have a liquid-crystalline mesophase in a suitable temperature range and low viscosity. None of the hitherto-disclosed series of compounds having a liquid-crystalline mesophase includes a single compound which meets all these requirements. Mixtures of two to 25, preferably three to 18, compounds are therefore generally prepared in order to obtain substances which can be used as LC phases. However, it has not been possible to prepare optimum phases easily in this way since no liquid-crystal materials having significantly negative dielectric anisotropy and adequate long-term stabili