Liquid crystal displays and liquid crystalline media with homeotropic alignment

Patent metadata

Field	Value
Publication number	US-9868904-B2
Application number	US-201113825680-A
Country	US
Kind code	B2
Filing date	Aug 29, 2011
Priority date	Sep 25, 2010
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

The present invention relates to liquid-crystalline media (LC media) having negative or positive dielectric anisotropy comprising self-aligning mesogens (SAMs) which effect homeotropic (vertical) alignment of the LC media at a surface or the cell walls of a liquid-crystal display (LC display). The invention therefore also encompasses LC displays having homeotropic alignment of the liquid-crystalline medium (LC medium) without conventional imide alignment layers. The LC media may be supplemented by a polymerizable or polymerized component, which serves for stabilization of the alignment, for adjustment of the tilt angle and/or as passivation layer.

First claim

The invention claimed is:

1. A LC medium with negative dielectric anisotropy, said medium comprising a low-molecular-weight liquid-crystalline component and one or more organic compounds, where the organic compound contains at least one polar anchor group and at least one ring group, wherein the polar anchor group of the organic compound contains at least one OH structure or an N atom in a primary or secondary or tertiary amino group, and wherein the anchor group is not comprised of a OH group which is a screened OH group as in 2,6-di-tert-butylphenol, said LC medium additionally comprising a polymerizable or polymerized component, where the polymerized component is obtainable by polymerization of a polymerizable component.

2. The LC medium according to claim 1 , wherein the organic compound has a relative molar mass of greater than 100 g/mol.

3. The LC medium according to claim 1 , wherein the polar anchor group of the organic compound denotes a group of the formula R 2 , where
R 2 denotes straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may be replaced by —NR 0 —, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that N, O and/or S atoms are not linked directly to one another, and in which, in addition, one or more tertiary carbon atoms (CH groups) may be replaced by N, and in which, in addition, one or more H atoms may be replaced by F or Cl, with the proviso that the radical R 2 contains one or more hetero atoms N, S and/or O, and R 0 is H or C 1-12 -alkyl.

4. The LC medium according to claim 1 , wherein the organic compound encompasses a compound of the formula
MES-R 2 ,
in which
MES denotes a mesogenic group containing at least one ring system, and

R 2 denotes a polar anchor group.

5. The LC medium according to claim 1 , wherein the organic compound encompasses a compound of the formula I:
R 1 -A 1 -(Z 2 -A 2 ) m1 -R 2   (I)

in which

A 1 and A 2 each, independently of one another, denote an aromatic, heteroaromatic, alicyclic or heterocyclic group, which may also contain fused rings, and which may also be mono- or polysubstituted by a group L,
L in each case, independently of one another, denotes —OH, —(CH 2 ) n1 —OH, F, Cl, Br, I, —CN, —NO 2 , —NCO, —NCS, —OCN, —SCN, —C(═O)N(R 0 ) 2 , —C(═O)R 0 , —N(R 0 ) 2 , —(CH 2 ) n1 —N(R 0 ) 2 , optionally substituted silyl, optionally substituted aryl or cycloalkyl having 6 to 20 C atoms, or straight-chain or branched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 25 C atoms, in which, in addition, one or more H atoms may be replaced by F or Cl,
Z 2 in each case, independently of one another, denotes —O—, —S—, —CO—, —CO—O—, —OCO—, —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 ) n1 —, —CF 2 CH 2 —, —CH 2 CF 2 —, —(CF 2 ) n1 —, —CH═CH—, —CF═CF—, —C≡C—, —CH═CH—COO—, —OCO—CH═CH—, CR 0 R 00 or a single bond,
R 0 and R 00 each, independently of one another, denote H or alkyl having 1 to 12 C atoms,
R 1 , R 2 , independently of one another, denote H, halogen, straight-chain, branched or cyclic alkyl having 1 to 25 C atoms, in which, in addition, one or more non-adjacent CH 2 groups may be replaced by —NR 0 —, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that N, O and/or S atoms are not linked directly to one another, and in which, in addition, one or more tertiary carbon atoms (CH groups) may be replaced by N, and in which, in addition, one or more H atoms may be replaced by F or Cl,
with the proviso that at least the radical R 2 contains one or more heteroatoms selected from N, S and/or O,
m1 denotes 0, 1, 2, 3, 4 or 5, and
n1 denotes 1, 2, 3 or 4.

6. The LC medium according to claim 5 , wherein
Z 2 denotes a single bond.

7. The LC medium according to claim 4 , wherein R 2 encompasses a group of the sub-formula (A1)
-Sp-[X 2 —Z 3 —] k X 1   (A1)

in which
Sp denotes a spacer group or a single bond,
X 1 denotes a group —NH 2 , —NHR 11 , —NR 11 2 , —OH, —(CO)OH or a group of the formula

R 0 denotes H or alkyl having 1 to 12 C atoms,
X 2 in each case independently denotes —NH—, —NR 11 —, —O— or a single bond,
Z 3 in each case independently denotes an alkylene group having 1-15 C atoms, carbocyclic rings having 5 or 6 C atoms, or combinations of one or more rings and alkylene groups, in each of which hydrogen may be replaced by —OH, —OR 11 , —(CO)OH, —NH 2 , —NHR 11 , —NR 11 2 or halogen,
R 11 in each case independently denotes a halogenated or unsubstituted alkyl radical having 1 to 15 C atoms, where, in addition, one or more CH 2 groups in this radical may each be replaced, independently of one another, by —C≡C—, —CH═CH—, —(CO)O—, —O(CO)—, —(CO)— or —O— in such a way that O atoms are not linked directly to one another, and where two radicals R 11 may be linked to one another to form a ring, and
k denotes 0, 1, 2 or 3.

8. The LC medium according to claim 5 , comprising the compounds of the formula I in a concentration of less than 10% by weight.

9. The LC medium according to claim 1 , wherein the polymerizable or polymerized component is one or more polymerizable compounds of the formula M or a polymerized component which comprises one or more compounds of the formula M in polymerised form:
P a -(Sp a ) s1 -A 2 -(Z 1 -A 1 ) n -(Sp b ) s2 -P b   M

in which the individual radicals have the following meanings:

P a , P b each, independently of one another, denote a polymerizable group,
Sp a , Sp b on each occurrence, identically or differently, denote a spacer group,
s1, s2 each, independently of one another, denote 0 or 1,
A 1 , A 2 each, independently of one another, denote a radical selected from the following groups:
a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 4,4′-bicyclohexylene, in which, in addition, one or more non-adjacent CH 2 groups may be replaced by —O— and/or —S— and in which, in addition, one or more H atoms may be replaced by F,
b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which, in addition, one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L,
c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L,
d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals having 5 to 20 cyclic C atoms, one or more of which may, in addition, be replaced by heteroatoms,

n denotes 0, 1, 2 or 3,
Z 1 in each case, independently of one another, denotes —CO—O—, —O—CO—, —CH 2 O—, —OCH 2 —, —CF 2 O—, —OCF 2 —, or where n′ is 2, 3 or 4, —O—, —CO—, —C(R c R d )—, —CH 2 CF 2 —, —CF 2 CF 2 — or a single bond,
and R c R d are H or C 1-6 -alkyl.

10. The LC medium according to claim 5 , wherein the compound of the formula I contains one or more polymerizable groups.

11. A LC display comprising an LC cell having two substrates and at least two electrodes, where at least one substrate is transparent to light and at least one substrate has one or two electrodes, and a layer of an LC medium according to claim 5 located between the substrates,
where the organic compound or the compound of the formula I i

Assignees

• Graziano Archetti
• Taugerbeck Andreas
• Merck Patent Gmbh

Inventors

• Graziano Archetti
• Taugerbeck Andreas

Classifications

• C09K19/3003

  Compounds containing at least two rings in which the different rings are directly linked (covalent bond) · CPC title

• G02F1/133711

  by organic films, e.g. polymeric films · CPC title

• C09K19/0403

  the structure containing one or more specific, optionally substituted ring or ring systems · CPC title

• C09K19/42 Primary

  Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40 · CPC title

• C07J9/00

  Normal steroids containing carbon, hydrogen, halogen or oxygen substituted in position 17 beta by a chain of more than two carbon atoms, e.g. cholane, cholestane, coprostane · CPC title