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US-12624291-B2 - Liquid-crystalline medium and liquid-crystal display comprising the same and compounds

US12624291B2US 12624291 B2US12624291 B2US 12624291B2US-12624291-B2

Abstract

A liquid-crystalline medium, preferably having a nematic phase, comprising one or more compounds of formula C the use thereof in an energy-efficient electro-optical display, particularly in an active-matrix display based on the IPS or FFS effect, displays of this type which contain a liquid-crystalline medium of this type, and the use of the compounds of formula C for improvement of the contrast and/or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.

Inventors

  • Sven Christian Laut
  • Martina Windhorst
  • Atsutaka Manabe
  • Constanze Brocke

Assignees

  • MERCK PATENT GMBH

Dates

Publication Date
20260512
Application Date
20211220
Priority Date
20201222

Claims (20)

  1. 1 . A liquid-crystalline medium, comprising one or more compounds of formula C: in which denotes denotes, in each occurrence independently of one another, R C1 and R C2 independently of one another, denote an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; and wherein the respective rings are each optionally substituted by one or two alkyl groups; one or more compounds of formula B: in which denotes denotes, in each occurrence independently of one another, n denotes 1 or 2; denotes an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; and X 1 denotes F, Cl, or a fluorinated alkyl, alkenyl, alkoxy, or alkenyloxy group having 1 to 4 C atoms; and one or more dielectrically neutral compounds of formula V: in which R 51 and R 52 independently of one another, denote an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; if present, each, independently of one another, denote Z 51 to Z 53 each, independently of one another, denote —CH 2 —CH 2 —, —CH 2 —O—, —CH═CH—, —C≡C—, —COO—, or a single bond; and i and i each, independently of one another, denote 0 or 1, wherein the respective rings are each optionally substituted by one or two alkyl groups; and wherein the liquid-crystalline medium has a positive dielectric anisotropy.
  2. 2 . The medium according to claim 1 , further comprising one or more compounds selected from the group consisting of compounds of formulae II and III: in which R 2 and R 3 independently of one another, denote an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; on each appearance, independently of one another, denote L 21 and L 22 denote H or F; X 2 denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms, or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms; m denotes 0, 1, 2, or 3; on each appearance, independently of one another, denote L 31 and L 32 independently of one another, denote H or F; X 3 denotes halogen, halogenated alkyl or alkoxy having 1 to 3 C atoms, or halogenated alkenyl or alkenyloxy having 2 or 3 C atoms, F, Cl, —OCF 3 , —OCHF 2 , —O—CH 2 CF 3 , —O—CH═CF 2 , —O—CH═CH 2 , or —CF 3 ; Z 3 denotes —CH 2 CH 2 —, —CF 2 CF 2 —, —COO—, trans-CH═CH—, trans —CF═CF—, —CH 2 O—, or a single bond; and n denotes 0, 1, 2, or 3, wherein the respective rings are each optionally substituted by one or two alkyl groups.
  3. 3 . The medium according to claim 1 , further comprising one or more dielectrically neutral compounds of formula IV: in which R 41 and R 42 independently of one another, denote an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; independently of one another and, if occurs twice, also these independently of one another, denote Z 41 and Z 42 independently of one another and, if Z 41 occurs twice, also these independently of one another, denote —CH 2 CH 2 —, —COO—, trans-CH═CH—, trans-CF═CF—, —CH 2 O—, —CF 2 O—, —C≡C—, or a single bond; p denotes 0, 1, or 2; R 51 and R 52 independently of one another, denote an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; wherein the respective rings are each optionally substituted by one or two alkyl groups.
  4. 4 . The medium according to claim 1 , in which in the one or more compounds of formula B: denotes
  5. 5 . The medium according to claim 1 , further comprising one or more compounds of formula I: in which denotes denotes n denotes 0 or 1; R 11 and R 12 independently of each other denotes an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen, or R 11 alternatively denotes R 1 and R 12 alternatively denotes X 1 ; R 1 denotes an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen; and X 1 denotes F, Cl, fluorinated alkyl, fluorinated alkenyl, fluorinated alkoxy, or fluorinated alkenyloxy, from which compounds of formulae B, VII, and IX are excluded: and wherein the respective rings, are each optionally substituted by one or two alkyl groups.
  6. 6 . The medium according to claim 1 , further comprising one or more compounds selected from the group of compounds of formulae VI to IX: wherein R 61 , R 62 , R 71 , R 72 , R 81 , R 82 , R 91 , and R 92 independently of each other, denotes an alkyl radical having 1 to 15 C atoms, wherein one or more CH 2 groups in these radicals are each optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, 1,3-cyclopentenylene, 1,2-cyclopropyl, alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, in such a way that O atoms are not linked directly to one another, and in which one or more H atoms are optionally replaced by halogen I denotes 0 or 1; denotes denotes Z 8 denotes —(C═O)—O—, —CH 2 —O—, —CF 2 —O—, or —CH 2 —CH 2 —; o denotes 0 or 1; denotes p and q independently of each other, denote 0 or 1, wherein the respective rings are each optionally substituted by one or two alkyl groups, and the compounds of formula VII are excluded from the compounds of formula IX.
  7. 7 . The medium according to claim 1 , having a total concentration of the one or more compounds of formula B in the medium as a whole of 1% or more to 60% or less.
  8. 8 . The medium according to claim 1 , further comprising one or more chiral compounds and/or one or more stabilizers.
  9. 9 . An electro-optical display or electro-optical component, comprising the liquid-crystalline medium according to claim 1 .
  10. 10 . The electro-optical display according to claim 9 , wherein the electro-optical display is based on an IPS- or FFS mode.
  11. 11 . The electro-optical display according to claim 9 , wherein the electro-optical display comprises an active-matrix addressing device.
  12. 12 . A method of using the medium according to claim 1 , comprising incorporating the medium in an electro-optical display or in an electro-optical component.
  13. 13 . A process for preparing the liquid-crystalline medium according to claim 1 , comprising mixing one or more compounds of formula C and one or more compounds of formula B with one or more additional mesogenic compounds and optionally one or more additives.
  14. 14 . The liquid-crystalline medium according to claim 1 , wherein one or more CH 2 groups in R C1 and R C2 are each replaced, independently of one another, by 1,2-cyclopropyl, 1,3-cyclopentyl, 1,3-cyclopentenylene, or alkyl, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms.
  15. 15 . The liquid-crystalline medium according to claim 14 , wherein R C1 and R C2 are independently of one another alkyl or alkenyl having 2 to 7 C atoms, in which one —CH 2 — group is optionally replaced by cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, or 1,3-cyclo-pentenylene.
  16. 16 . The liquid-crystalline medium according to claim 15 , wherein R C1 and R C2 are independently of one another alkyl or alkenyl having 2 to 7 C atoms, in which one —CH 2 — group is optionally replaced by cyclopropylene or 1,3-cyclopentenylene.
  17. 17 . The liquid-crystalline medium according to claim 1 , wherein R 1 denotes an alkyl radical having 1 to 7 C atoms, wherein one or more CH 2 groups in this radical each is optionally replaced, independently of one another, by —CH═CH—, —C≡C—, —CF 2 O—, —OCF 2 —, —O—, —(CO)—O—, —O—(C═O)—, cyclopropylene, 1,3-cyclobutylene, 1,3-cyclopentylene, or 1,3-cyclo-pentenylene.
  18. 18 . The liquid-crystalline medium according to claim 2 , wherein R 2 and R 3 , independently of one another, denote alkyl, alkoxy, fluorinated alkyl, or fluorinated alkoxy having 1 to 7 C atoms, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms.
  19. 19 . The liquid-crystalline medium according to claim 4 , wherein R 1 denotes alkyl, alkoxy, fluorinated alkyl, fluorinated alkoxy, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl.
  20. 20 . The liquid-crystalline medium according to claim 5 , wherein R 11 and R 12 , independently of each other, denote alkyl, alkoxy, fluorinated alkyl having 1 to 7 C atoms, wherein one CH 2 group is optionally replaced by a 1,2-cyclopropyl group, by a 1,3-cyclopentyl group, or by a 1,3-cyclopentenylene group, or fluorinated alkoxy, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms, and R 1 denotes alkyl, alkoxy, fluorinated alkyl, or fluorinated alkoxy, wherein one CH 2 group is optionally replaced by a 1,2-cyclopropyl group, by a 1,3-cyclopentyl group, or by a 1,3-cyclopentenylene group, alkenyl, alkenyloxy, alkoxyalkyl, or fluorinated alkenyl having 2 to 7 C atoms.

Description

The present invention relates to novel liquid crystalline media, in particular for use in energy-efficient liquid-crystal displays, and to these liquid-crystal displays, particularly to liquid-crystal displays which use the IPS (in-plane switching) or, preferably, the FFS (fringe field switching) effect using dielectrically positive liquid crystals. The last one is also called XB-FFS (extra brightness FFS) effect occasionally. For this effect dielectrically positive liquid crystals are used, which comprise one or more compounds having at the same time a high dielectric constant parallel to the molecular director and perpendicular to the molecular director, leading to a large average dielectric constant and a high dielectric ratio and, preferably, to a relatively small dielectric anisotropy at the same time. The liquid crystalline media optionally additionally comprise dielectrically negative compounds, dielectrically neutral compounds or both. The liquid crystalline media are used in a homogeneous (i.e. planar) initial alignment. The liquid-crystal media according to the invention have a positive dielectric anisotropy and comprise compounds having at the same time large dielectric constants parallel and perpendicular to the molecular director. The media are distinguished by a particularly good representation of the black state, primarily attributable to their very low scattering. This in turn is brought about especially by their high elastic constants. High elastic constants may lead to higher values of the rotational viscosity (γ1), too. And consequently, to higher values of the ratio γ1/k22 of the rotational viscosity (γ1) to the elastic constant for the twist deformation (k22), which then leads to higher response times. Since k22 is approximately proportional to the elastic constant k11 for splay deformation (the value of k22 is typically about half the value of k11), this can easily and conveniently be approximated determining γ1 and k11. The contrast of an LC Display can be improved, on the one hand by a higher transmittance, which can be achieved by a higher ε⊥ in an FFS cell layout. And, on the other hand, it can be improved by a better dark state. The latter, i.e. the dark state, is strongly influenced, amongst others, by the scattering parameter. Here liquid crystalline media having high elastic constants lower the scattering and therefore improve the contrast of an LCD. This also leads to their excellent performance in the displays according to the invention. IPS and FFS displays using dielectrically positive liquid crystals are well known in the field and have been widely adopted for various types of displays like e.g. desk top monitors and TV sets, but also for mobile applications. However, recently, IPS and in particular FFS displays using dielectrically negative liquid crystals are widely adopted. The latter ones are sometimes also called or UB-FFS (ultra bright FFS). Such displays are disclosed e.g. in US 2013/0207038 A1. These displays are characterized by a markedly increased transmission compared to the previously used IPS- and FFS displays, which have been dielectrically positive liquid crystals. These displays using conventional, dielectrically negative liquid crystals, however, have the severe disadvantage of requiring a higher operation voltage than the respective displays using dielectrically positive liquid crystals. Liquid crystalline media used for UB-FFS have a dielectric anisotropy of −0.5 or less and preferably of −1.5 or less. Liquid crystalline media used for HB-FFS (high brightness FFS) have a dielectric anisotropy of 0.5 or more and preferably of 1.5 or more. Liquid crystalline media used for HB-FFS comprising both dielectrically negative and dielectrically positive liquid crystalline compounds, respectively mesogenic compounds are disclosed e.g. in US 2013/0207038 A1. These media feature rather large values of ε⊥ and of εav. already, however, their ratio of (ε⊥/Δε) is relatively small. According to the present invention, however, the IPS or the FFS effect with dielectrically positive liquid crystalline media in a homogeneous alignment are preferred. Industrial application of this effect in electro-optical display elements requires LC phases which have to meet a multiplicity of requirements. Particularly important here are chemical resistance to moisture, air and physical influences, such as heat, radiation in the infrared, visible and ultraviolet regions, and direct (DC) and alternating (AC) electric fields. Furthermore, LC phases which can be used industrially are required to have a liquid-crystalline mesophase in a suitable temperature range and low viscosity. None of the series of compounds having a liquid-crystalline mesophase that have been disclosed hitherto 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