Liquid-crystal displays having homeotropic alignment

Patent metadata

Field	Value
Publication number	US-9249355-B2
Application number	US-201213983312-A
Country	US
Kind code	B2
Filing date	Jan 9, 2012
Priority date	Feb 5, 2011
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

The present invention relates to liquid-crystalline media (LC media) comprising self-aligning additives 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 are optionally supplemented by a polymerisable or polymerised component, which serves for stabilisation of the alignment, for adjustment of the tilt angle and/or as passivation layer.

First claim

The invention claimed is:

1. 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 a layer of an LC medium located between the substrates, which LC medium comprises
a low-molecular-weight liquid-crystalline component and
an organic compound, which contains at least one polar anchor group and at least one long-chain non-polar radical having at least 8 C atoms,
where the organic compound is suitable for effecting homeotropic alignment of the LC medium with respect to the substrate surfaces, and
which LC display is a VA-IPS display containing an LC medium having positive dielectric anisotropy and interdigital electrodes arranged on at least one substrate.

2. The LC display according to claim 1 , wherein the LC medium further comprises a polymerizable or polymerized component, which is not identical to said organic compound containing at least one polar anchor group and at least one long-chain non-polar radical having at least 8 C atoms, where the polymerized component has been obtained by polymerization of a polymerizable component.

3. The LC display according to claim 1 , wherein in the LC medium the organic compound is a compound of formula (I)
(R 1 ) n —R 2   (I)

in which
R 1 denotes a straight-chain or branched alkyl having 8 to 20 C atoms, in which one or more non-adjacent CH 2 groups are optionally replaced by —CH═CH—, —CF═CH—, —CH═CF— or —C≡C—, in which one CH 2 group is optionally replaced by a cycloalkylene group having 3 to 8 C atoms and in which one or more H atoms are optionally replaced by F or Cl,
R 2 denotes the polar anchor group, and
n denotes 1 or 2.

4. The LC display according to claim 1 , wherein in the LC medium the organic compound is a compound of formula (I)
(R 1 ) n —R 2   (I)

in which
n denotes 1 or 2,
R 1 denotes a straight-chain or branched alkyl having 8 to 20 C atoms, in which one or more non-adjacent CH 2 groups are optionally replaced by —CH═CH—, —CF═CH—, —CH═CF— or —C═C—, in which one CH 2 group is optionally replaced by a cycloalkylene group having 3 to 8 C atoms and in which one or more H atoms are optionally replaced by F or Cl, and
R 2 is of 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 —NH 2 , —NHR 11 , —NR 11 2 , —OR 11 , —OH,

R 0 denotes H or alkyl having 1 to 12 C atoms,
X 2 denotes —NH—, —NR 11 —, —O— or a single bond,
Z 3 in each case, independently of one another, 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 are optionally replaced by —OH, —OR 11 , —(CO)OH, —NH 2 , —NHR 11 , —NR 11 2 or halogen,
R 11 denotes a halogenated or unsubstituted alkyl radical having 1 to 15 C atoms, in which one or more CH 2 groups are each optionally 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 are optionally linked to one another to form a ring, or H, and k denotes 0, 1, 2 or 3.

5. A LC medium comprising
A) a low-molecular-weight liquid-crystalline component and
B) an organic compound of formula (I)
(R 1 ) n —R 2   (I)

in which
n denotes 1 or 2,
R 1 denotes a straight-chain or branched alkyl having 8 to 20 C atoms, in which one or more non-adjacent CH 2 groups are optionally replaced by —CH═CH—, —CF═CH—, —CH═CF— or —C═C—, in which one CH 2 group is optionally replaced by a cycloalkylene group having 3 to 8 C atoms and in which one or more H atoms are optionally replaced by F or Cl, and
R 2 is of 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 —NH 2 , —NHR 11 , —NR 11 2 , —OR 11 , —OH,

R 0 denotes H or alkyl having 1 to 12 C atoms,
X 2 denotes —NH—, —NR 11 —, —O— or a single bond,
Z 3 in each case, independently of one another, 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 are optionally replaced by —OH, —OR 11 , —(CO)OH, —NH 2 , —NHR 11 , —NR 11 2 or halogen,
R 11 denotes a halogenated or unsubstituted alkyl radical having 1 to 15 C atoms, in which one or more CH 2 groups are each optionally 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 are optionally linked to one another to form a ring, or H, and k denotes 0, 1, 2 or 3,
and
C) a polymerizable or polymerized component, which is not identical to said organic compound, where the polymerized component has been obtained by polymerization of a polymerizable component.

6. The LC medium according to claim 5 , wherein the organic compound is a compound of formula (I')
R 1 —R 2   (I')

in which R 1 and R 2 are as defined for the compound of formula (I).

7. The LC medium according to claim 5 , wherein in the compound of formula (I),
R 1 denotes an alkyl group having 8 to 20 C atoms.

8. A LC medium comprising
A) a low-molecular-weight liquid-crystalline component and
B) an organic compound, and
C) a polymerizable or polymerized component, which is not identical to said organic compound, where the polymerized component has been obtained by polymerization of a polymerizable component,
wherein the organic compound is a compound of formula I-1 to I-128 or I-140 to I-143

9. The LC medium according to claim 5 , which comprises the organic compound at a concentration of less than 10% by weight.

10. The LC medium according to claim 5 , wherein the polymerizable component is a compound of formula M or the polymerized component comprises one or more compounds of formula M in polymerized form
P a -(Sp a ) s1 -A 2 -(Z 1 -A 1 ) n -(Sp b ) s2 -P b   M

in which
P a , P b each, independently of one another, denote a polymerisable 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

Assignees

• Archetti Graziano
• Taugerbeck Andreas
• Merck Patent Gmbh

Inventors

• Archetti Graziano
• Taugerbeck Andreas

Classifications

• C09K19/44

  containing compounds with benzene rings directly linked · CPC title

• C09K2019/0466

  the linking chain being a -CF2O- chain · CPC title

• C09K19/3003 Primary

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

• C09K19/56 Primary

  Aligning agents · CPC title

• C09K19/54 Primary

  Additives having no specific mesophase {characterised by their chemical composition} · CPC title