Liquid-crystalline medium

Patent metadata

Field	Value
Publication number	US-11466213-B2
Application number	US-201716343147-A
Country	US
Kind code	B2
Filing date	Oct 16, 2017
Priority date	Oct 19, 2016
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

The invention relates to a liquid-crystalline medium having negative dielectric anisotropy comprising one or more compounds of formula Iandone or more compounds selected from the group of the compounds of the formulae IIA, IIB and IIC,wherein the groups and parameters have the meanings indicated in claim 1, to a guest-host liquid crystal medium derived therefrom comprising one or more dichroic dyes and the use of said medium in devices such as light shutters, switchable windows, switchable mirrors and guest-host displays. The invention further relates to devices containing the liquid crystalline medium according to the invention.

First claim

The invention claimed is:

1. A liquid-crystalline medium, comprising one or more compounds
of formula I-1 or I-2

wherein
R 1 denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms,
A 12 denotes

A 11 denotes

L H and L 12 independently of one another, denote H or F, and
Z 1 denotes —CO—O—, —O—CO—, —CH 2 O—, —OCH 2 —, —CH 2 CH 2 —, —OCF 2 —, —CF 2 O—, or a single bond,
and
one or more compounds of formulae HA, IIB or IIC,

in which
R 2A , R 2B and R 2C each, independently of one another, denote H, an alkyl radical having 1 to 15 C atoms or alkenyl radical having 2 to 15 C atoms which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where one or more CH 2 groups in these radicals may be replaced by —O—, —S—, —C≡C—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another, or a cycloalkyl ring having 3 to 6 C atoms,
L 1-4 each, independently of one another, denote F, Cl, CF 3 or CHF 2 ,
Z 2 and Z 2′ each, independently of one another, denote a single bond, —CH 2 CH 2 —, —CH═CH—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —C(O)O—, —OC(O)—, —C 2 F 4 —, —CF═CF—, or —CH═CHCH 2 O—,
p denotes 1 or 2,
q denotes 0 or 1, and
denotes 1 to 6
and
one or more dichroic dyes selected from the following formulae

wherein said liquid-crystalline medium has a negative dielectric anisotropy and
wherein the proportion of the one or more compounds of formula I-1 or I-2 in the mixture as a whole is up to 20% by weight.

2. The liquid-crystalline medium according to claim 1 , wherein the one or more compounds is a compound of formula I-1.

3. The liquid-crystalline medium according to claim 1 , wherein the compound of formulae IIA, IIB or IIC is of the following formulae:

wherein
alkyl and alkyl* each, independently of one another, denote a straight-chain alkyl radical having 1-6 C atoms,
alkenyl denotes a straight chain alkenyl radical having 2 to 6 C atoms, and (O) denotes —O— or a single bond.

4. The liquid-crystalline medium according to claim 1 , wherein the one or more dichroic dyes is a compound of formulae

5. The liquid-crystalline medium according to claim 1 , wherein the concentration of the dichroic dye or dyes is 1% by weight or more.

6. The liquid-crystalline medium according to claim 1 , wherein the medium additionally comprises one or more terphenyls of formulae T-1 to T-21,

in which
R denotes a straight-chain alkyl or alkoxy radical having 1-7 C atoms or straight-chain alkenyl radical having 2-7 C atoms, and
m denotes 1-6.

7. The liquid-crystalline medium according to claim 1 , wherein the medium additionally comprises one or more compounds of formulae O-1 to O-16,

in which
R 1 and R 2 each, independently of one another, denote H, an alkyl radical having 1 to 15 C atoms or alkenyl radical having 2 to 15 C atoms which is un-substituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, where one or more CH 2 groups in these radicals may be replaced by —O—, —S—, —CF 2 O—, —OCF 2 —, —OC—O— or —O—CO— in such a way that O atoms are not linked directly to one another, or a cycloalkyl ring having 3 to 6 C atoms.

8. The liquid-crystalline medium according to claim 1 , wherein the proportion of the one or more compounds of formula I-1 or I-2 in the mixture as a whole is 5-10% by weight.

9. A process for the preparation of a liquid-crystalline medium according to claim 1 , wherein the one or more compounds of the formula I-1 or I-2 is mixed with one or more compounds of formulae IIA, IIB or IIC, and one or more of the dichroic dyes, and optionally one or more additives and optionally at least one polymerisable compound.

10. A method which comprises adding the liquid-crystalline medium according to claim 1 into a light shutter, switchable window, guest-host display or automotive mirror.

11. An electro-optical device, comprising as dielectric, a liquid-crystalline medium according to claim 1 .

12. The electro-optical device according to claim 11 , wherein the device is a light shutter, a switchable window, a guest-host display or a switchable mirror.

13. The liquid-crystalline medium according to claim 1 , wherein the proportion of the one or more compounds of formula I-1 or I-2 in the mixture as a whole is up to 15% by weight.

14. The liquid-crystalline medium according to claim 13 , wherein the proportion of the one or more compounds of formula I-1 or I-2 in the mixture as a whole is up to 12% by weight or less.

15. The liquid-crystalline medium according to claim 5 , wherein the concentration of the dichroic dye or dyes is 1.5% by weight or more.

16. The liquid-crystalline medium according to claim 15 , wherein the concentration of the dichroic dye or dyes is 2% by weight or more.

17. The liquid-crystalline medium according to claim 1 , wherein the one or more compounds is a compound of formula I-1, in which Z 1 denotes a single bond.

18. The liquid-crystalline medium according to claim 1 , wherein the one or more compounds is a compound of formula I-2.

Assignees

• Merck Patent Gmbh

Inventors

• Lee Jung-Min
• Bae Hyun-Woo
• Song Dong-Mee
• Yun Yong-Kuk

Classifications

• C09K2219/13

  used in the technical field of thermotropic switches · CPC title

• C09K2019/301

  Cy-Cy-Ph · CPC title

• C09K2019/122

  Ph-Ph · CPC title

• C09K19/601 Primary

  Azoic · CPC title

• C09K2019/3016

  Cy-Ph-Ph · CPC title