Liquid-crystal medium, and electro-optical display containing the medium

• US 20020084443A1
• Filed: 03/26/2001
• Published: 07/04/2002
• Est. Priority Date: 03/24/2000
• Status: Active Grant

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Heckmeier, Michael, Bremer, Matthias, Klement, Dagmar
• Granted Patent: US 6,638,581 B2
• Time in Patent Office: Days
• US Class Current: 252/299.63
• CPC Class Codes: C09K 19/30 containing saturated or unsaturated non-aromatic rings, e.g. cyclohexane rings
• CPC Class Codes: C09K 19/3003 Compounds containing at least two rings in which the different rings are directly linked (covalent bond)
• CPC Class Codes: C09K 19/44 containing compounds with benzene rings directly linked
• CPC Class Codes: C09K 2019/3027 Compounds comprising 1,4-cyclohexylene and 2,3-difluoro-1,4-phenylene
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition

Abstract

A liquid-crystal medium comprising a) at least one compound of the formula I and b) at least one compound of the formula II

wherein R¹¹, R¹², R²¹, R²², A¹, A²¹, Z²¹, Z²², L²¹, L²² and I are as defined herein are suitable for use in ECB, VAN, IPS, GH and ASM-PA LCD displays.

Claims

1. A nematic liquid-crystal medium comprising:

a) one or more dielectrically negative compound(s) of formula I

in which

R¹¹ is alkoxy having 1 to 7 carbon atoms or alkenyloxy having 2 to 7 carbon atoms,

and, in the case where

R¹¹ can also be alkyl having 1 to 7 carbon atoms; and

R¹² is alkyl having 1 to 7 carbon atoms, alkoxy having 1 to 7 carbon atoms, alkenyloxy having 2 to 7 carbon atoms,

b) one or more dielectrically negative compound(s) of formula II

in which

R²¹ is alkyl having 1 to 7 carbon atoms, alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

R²² is alkyl having 1 to 7 carbon atoms, alkoxy having 1 to 7 carbon atoms, or alkenyloxy having 2 to 7 carbon atoms,

Z²¹ and Z²² are, in each case, independently, —

CH₂—

CH₂-, —

CH═

CH—

, —

C—

C—

, —

COO—

or a single bond,

are, in each case, independently,

L²¹ and L²² are both C—

F or one of the two is N and the other is C—

F, and

I is 0 or 1,

the compounds of the formulae I and III being excluded,

c) optionally one or more dielectrically negative compound(s) of the formula III

in which

R³¹ and R³² are each, independently, alkyl having 1 to 7 carbon atoms, alkoxy having 1 to 7 carbon atoms or alkenyloxy having 2 to 7 carbon atoms,

Z³¹ is —

CH₂—

CH₂—

, —

CH═

CH—

, —

C═

C—

, —

COO—

or a single bond,

L³¹ and L³² are both C—

F or one of the two is N and the other is C—

F, and

L³³ and L³⁴ are both C—

F or one of the two is N and the other is C—

F.

2. A liquid-crystal medium according to claim 1, wherein said medium contains one or more compounds of formulae I1 to I3;

3. A liquid-crystal medium according to claim 1, wherein said medium contains one or more compounds of formula III.

4. A liquid-crystal medium according to claim 1, wherein said medium contains one or more compounds of formulae II1a to II1 e

5. A liquid-crystal medium according to claim 3, wherein said medium contains one or more compounds of formulae III1 to III3

6. A liquid-crystal medium according to claim 1, further comprising one or more dielectrically neutral compounds of formula IV

7. A liquid-crystal medium according to claim 1, wherein said medium contains

5%-80% of compounds of the formula I,

5%-90% of compounds of the formula II, and

0%-40% of compounds of the formula III.

8. In an electro-optical display containing a liquid-crystal medium, the improvement wherein said display contains a medium according to claim 1.

9. A display according to claim 8, wherein said display is an active matrix display.

10. In a method of generating an electro-optical effect using an electro-optical display, the improvement wherein a display according to claim 8 is used to generate said effect.

11. A liquid crystal medium according to claim 1, wherein said medium contains one or more dielectrically positive compound(s) of formula V

12. A liquid-crystal medium according to claim 1, wherein said medium contains one or more compounds of formula II1

13. A liquid-crystal medium according to claim 6, wherein said medium contains one or more compounds of formulae IV1 to IV3:

14. A liquid-crystal medium according to claim 6, wherein said medium contains one or more compounds of formula IV1a to IV1d, IV2a to IV2e, IV3a to IV3c and IV4a:

15. A liquid-crystal medium according to claim 11, wherein said medium contains one or more compounds of formulae V1 to V4:

16. A liquid-crystal medium according to claim 7, wherein said medium contains:

10%-40% of compounds of the formula I,

50%-90% of compounds of the formula II and

0%-40% of compounds of the formula III.

17. A liquid crystal medium according to claim 16, wherein said medium contains

15%-35% of compounds of the formula I,

60%-80% of compounds of the formula II and

0%-4 5% of compounds of the formula III.

18. A liquid-crystal medium according to claim 1, wherein said medium exhibits a nematic phase at −

30°

C. to 70°

C.

19. A liquid-crystal medium according to claim 1, wherein said medium has a birefringence value of 0.070 to 0.120.

20. A liquid-crystal medium according to claim 1, where said medium has a threshold voltage value of ≦

2.0 V.