LIQUID CRYSTALLINE MEDIUM

Abstract

A liquid-crystalline medium having a nematic phase comprising one or more compounds of formula I

##STR00001## and a negative dielectric component. It can be used in liquid-crystal electrooptical elements, particularly in liquid-crystal lenses. The mixtures have high optical anisotropy and high refractive index, simultaneously they are suitable for fast switching combined with low power consumption using a dual frequency addressing.

Claims

1. A liquid-crystalline medium having a nematic phase, the medium comprising one or more compounds of formula I ##STR00251## in which R.sup.1 is an alkyl radical having 1 to 15 C atoms, wherein one or more CH.sub.2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by CC, CHCH, ##STR00252## O, S, (CO)O or O(CO) in such a way that O or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F or Cl, or H, ##STR00253## on each appearance, independently of one another, denotes ##STR00254## ##STR00255## denotes ##STR00256## Z.sup.1 denotes CC, (CO)O or CF.sub.2O, Z.sup.2 denotes a single bond, (CO)O or CF.sub.2O, L.sup.11, L.sup.12, independently H, F or Cl, L.sup.13 H, CH.sub.3 or CH.sub.2CH.sub.3, X.sup.1CN, SCN, OCF.sub.3 or F, n denotes 1 or 2, and one or more additional compounds selected from the group of formulae II, III and VI to IX: ##STR00257## in which R.sup.21 and R.sup.22 are independently of each other defined as R.sup.1, preferably alkyl or alkoxy with 1 to 7 C-atoms, alkenyl, alkenyloxy or alkoxyalkyl with 2 to 7 C-atoms or C.sub.3-5-cycloalkyl-(CH.sub.2).sub.0-1, ##STR00258## is ##STR00259## n independently 0 or 1, ##STR00260## denotes ##STR00261## in which L.sup.3 is CH.sub.3, OCH.sub.3 or CH.sub.2CH.sub.3, ##STR00262## denotes ##STR00263## R.sup.31 and R.sup.32 are independently of each other defined as R.sup.1, R.sup.61 is defined as R.sup.1, R.sup.62 is defined as R.sup.1, and L.sup.61, L.sup.62 are independently H or methyl, l denotes 0 or 1, R.sup.71 is defined as R.sup.1, R.sup.72 is defined as R.sup.1, and L.sup.71, L.sup.72 independently H or methyl, ##STR00264## independently denote ##STR00265## R.sup.81 is defined as R.sup.1, R.sup.82 is defined as R.sup.1, L.sup.81, L.sup.82 independently H or methyl, ##STR00266## denotes ##STR00267## Z.sup.8 denotes (CO)O, CH.sub.2O, CF.sub.2O or CH.sub.2CH.sub.2, o denotes 0 or 1, R.sup.91 and R.sup.92 independently of one another have the meaning given for R.sup.72, ##STR00268## denotes ##STR00269## and p is 0 or 1.

2. The liquid-crystalline medium according to claim 1, comprising one or more compounds of the formula III.

3. The liquid-crystalline medium according to claim 1, comprising one or more compounds of the formula II.

4. The liquid-crystalline medium according to claim 1, further comprising one or more dielectrically neutral compounds selected from the group of formulae IV and V: ##STR00270## in which R.sup.41 and R.sup.42 are independently of one another, an alkyl radical having 1 to 15 C atoms, wherein one or more CH.sub.2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by CC, CHCH, ##STR00271## O, S, (CO)O, O(CO) in such a way that O or S atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by F or Cl, ##STR00272## independently of one another and, if ##STR00273## occurs twice, also these independently of one another, denote ##STR00274## Z.sup.41 and Z.sup.42 are independently of one another and, if Z.sup.41 occurs twice, also these independently of one another, denote CH.sub.2CH.sub.2, COO, trans-CHCH, trans-CFCF, CH.sub.2O, CF.sub.2O, CC or a single bond, p denotes 0, 1 or 2, R.sup.51 and R.sup.52, independently of one another, are defined as R.sup.41 and R.sup.42 ##STR00275## to ##STR00276## if present, each, independently of one another, denote ##STR00277## Z.sup.51 to Z.sup.53 each, independently of one another, denote CH.sub.2CH.sub.2, CH.sub.2O, CHCH, CC, COO or a single bond, and i and j each, independently of one another, denote 0 or 1, wherein the respective rings optionally may each be substituted by one or two alkyl groups.

5. Liquid-crystalline medium according to claim 1, wherein the one or more compounds of the formula I comprise one or more compounds selected from the group of the compounds of formulae I-1 to I-42: ##STR00278## ##STR00279## ##STR00280## ##STR00281## ##STR00282## ##STR00283## in which R.sup.1 is an alkyl radical having 1 to 15 C atoms, wherein one or more CH.sub.2 groups, including terminal C atoms, in this radical may each be replaced, independently of one another, by CC, CHCH, ##STR00284## O, S, (CO)O, O(CO) in such a way that O or S atoms are not linked directly to one another, and in which, in addition one or more H atoms may be replaced by F or Cl, or H, and L.sup.4 is F or H, L.sup.5 is H, CH.sub.3 or C.sub.3H.sub.7, and L.sup.6 is F or H.

6. The liquid-crystalline medium according to claim 1, wherein Z.sup.1 is CC and X.sup.1 is CN or SCN.

7. The liquid-crystalline medium according to claim 1, comprising one or more compounds of the formulae VI, VII, VIII, or IX.

8. The liquid-crystalline medium according to claim 1, wherein the total concentration of the compounds of formula I in the medium as a whole is 10% to 35% by weight of the medium.

9. The liquid-crystalline medium according to claim 1, wherein compounds of the formula V comprise one or more compounds selected from structures V-7 and/or V-8: ##STR00285## in which q is 0 or 1 R.sup.51 denotes alkyl having 1 to 7 C atoms or alkenyl having 2 to 7 C atoms, and R.sup.52 denotes alkyl having 1 to 7 C atoms, alkenyl having 2 to 7 C atoms or alkoxy having 1 to 6 C atoms.

10. An electro-optical lens or electro-optical display, comprising a liquid-crystalline medium according to claim 1.

11. An optical device comprising one or more electro-optical lenses according to claim 10, comprising a means to operate the lens by dual frequency addressing.

12. An electro-optical component comprising a medium according to claim 1 and having dual frequency addressing.

13. A process for the preparation of a liquid-crystalline medium according to claim 1, comprising mixing one or more compounds of formula I with one or more compounds selected from compounds of formulae II, III and VI to IX and optionally one or more additional mesogenic compounds and/or additives.

Description

EXAMPLES

[0344] The following examples explain the present invention without restricting it in any way. However, the physical properties make it clear to the person skilled in the art what properties can be achieved and in what ranges they can be modified. In particular, the combination of the various properties which can preferably be achieved is thus well defined for the person skilled in the art.

MIXTURE EXAMPLES

[0345] In the following exemplary mixtures are disclosed. AII %-values are % by weight.

[0346] The following mixtures are prepared and investigated.

TABLE-US-00007 Mixture Example 1 CPTU-5-S 22.0 T(N, I) [ C.]: 136.5 PPTU-5-S 10.0 n.sub.e [589 nm, 20 C.]: 1.8141 B(S)-2O-O4 5.0 n.sub.o [589 nm, 20 C.]: 1.5076 B(S)-2O-O5 5.0 n [589 nm, 20 C.]: 0.3065 B(S)-2O-O6 5.0 .sub. [1 kHz, 20 C.]: 10.6 PTY-5-O2 13.0 .sub. [1 kHz, 20 C.]: 8.2 CPTY-3-O2 12.0 [1 kHz, 20 C.]: 2.4 CPTY-5-O2 10.0 K.sub.1 [pN, 20 C.]: 24.4 PTP-3-O1 8.0 K.sub.3 [pN, 20 C.]: 28.2 CP-3-O2 10.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.15 100.0 V.sub.0 [V, 20 C.]: 3.40

[0347] The crossover frequency f.sub.CO of this mixture is 4.0 kHz.

Mixture Examples 1.1

[0348] 0.03% of the compound of the formula

##STR00246## [0349] is added to the mixture M-1. The resultant mixture M-1.1 is characterized by an improved stability against severe conditions, especially against exposure to light.

Mixture Examples 1.2

[0350] 0.4% of the compound of the formula

##STR00247## [0351] is added to the mixture M-1. The resultant mixture M-1.2 is characterized by an improved stability against severe conditions, especially against exposure to light.

Mixture Examples 1.3

[0352] 0.05% of the compound of the formula

##STR00248## [0353] is added to the mixture M-1. The resultant mixture M-1.3 is characterized by an improved stability against severe conditions, especially against exposure to light.

[0354] Alternatively, 0.05% of the compounds of one of the formulae

##STR00249## [0355] wherein the two a atoms bonded to the N atoms indicate radicals, or

##STR00250## [0356] can be added to the mixture M-1 for the purpose of stabilization.

TABLE-US-00008 Comparative Mixture Example 1 Compound weight % Physical properties CPZG-5-N 14.0 T(N, I) [ C.]: 106.2 PTY-3-O2 10.0 n.sub.e [589 nm, 20 C.]: 1.7192 PTY-5-O2 13.0 n.sub.o [589 nm, 20 C.]: 1.4978 CPTY-3-O2 12.0 n [589 nm, 20 C.]: 0.2214 CPTY-5-O2 16.0 .sub. [1 kHz, 20 C.]: 10.6 PTP-3-O1 6.0 .sub. [1 kHz, 20 C.]: 7.3 PTP-5-O1 5.0 [1 kHz, 20 C.]: 3.2 CP-3-O1 16.0 K.sub.1 [pN, 20 C.]: 16.1 CP-3-O2 8.0 K.sub.3 [pN, 20 C.]: 22.4 100.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.39 V.sub.0 [V, 20 C.]: 2.40

[0357] The crossover frequency f.sub.CO of this mixture is 12.5 kHz.

TABLE-US-00009 Mixture Example 2 Compound weight % Physical properties CPZG-5-N 14.0 T(N, I) [ C.]: 115 B(S)-2O-O4 5.0 n.sub.e [589 nm, 20 C.]: 1.7254 B(S)-2O-O5 5.0 n.sub.o [589 nm, 20 C.]: 1.5008 B(S)-2O-O6 5.0 n [589 nm, 20 C.]: 0.2246 PTY-5-O2 13.0 .sub. [1 kHz, 20 C.]: 11.9 CPTY-3-O2 12.0 .sub. [1 kHz, 20 C.]: 8.8 CPTY-5-O2 10.0 [1 kHz, 20 C.]: 3.0 PPTUI-3-2 12.0 K.sub.1 [pN, 20 C.]: 17.5 CP-3-O1 16.0 K.sub.3 [pN, 20 C.]: 22.3 CP-3-O2 8.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.27 100.0 V.sub.0 [V, 20 C.]: 2.55

[0358] The crossover frequency f.sub.CO of this mixture is 6.0 kHz.

TABLE-US-00010 Mixture Example 3 Compound weight % Physical properties CPZG-5-N 14.0 T(N, I) [ C.]: 99.5 B(S)-2O-O4 5.0 n.sub.e [589 nm, 20 C.]: 1.7161 B(S)-2O-O5 5.0 n.sub.o [589 nm, 20 C.]: 1.5028 B(S)-2O-O6 5.0 n [589 nm, 20 C.]: 0.2133 PTY-5-O2 13.0 .sub. [1 kHz, 20 C.]: 11.4 CPTY-3-O2 12.0 .sub. [1 kHz, 20 C.]: 8.8 CPTY-5-O2 10.0 [1 kHz, 20 C.]: 2.6 PTP-3-O1 7.0 .sub.1 [mPa s, 20 C.]: 238 PTP-2-O1 5.0 K.sub.1 [pN, 20 C.]: 15.6 CP-3-O1 16.0 K.sub.3 [pN, 20 C.]: 20.5 CP-3-O2 8.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.31 100.0 V.sub.0 [V, 20 C.]: 2.59

[0359] The crossover frequency f.sub.CO of this mixture is 10 kHz.

TABLE-US-00011 Mixture Example 4 Compound weight % Physical properties CPZG-5-N 14.0 T(N, I) [ C.]: 102.5 B(S)-2O-O4 8.0 n.sub.e [589 nm, 20 C.]: 1.7276 B(S)-2O-O5 8.0 n.sub.o [589 nm, 20 C.]: 1.5046 B(S)-2O-O6 8.0 n [589 nm, 20 C.]: 0.2230 PTY-5-O2 13.0 .sub. [1 kHz, 20 C.]: 12.5 CPTY-3-O2 12.0 .sub. [1 kHz, 20 C.]: 9.9 PPTUI-3-2 14.0 [1 kHz, 20 C.]: 2.6 CP-3-O1 15.0 K.sub.1 [pN, 20 C.]: 16.5 CP-3-O2 8.0 K.sub.3 [pN, 20 C.]: 20.8 100.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.26 V.sub.0 [V, 20 C.]: 2.65

[0360] The crossover frequency f.sub.CO of this mixture is 7.0 kHz.

TABLE-US-00012 Mixture Example 5 Compound weight % Physical properties CPZG-5-N 14.0 T(N, I) [ C.]: 111 B(S)-2O-O4 7.0 n.sub.e [589 nm, 20 C.]: 1.7318 B(S)-2O-O5 8.0 n.sub.o [589 nm, 20 C.]: 1.5034 B(S)-2O-O6 5.0 n [589 nm, 20 C.]: 0.2284 PTY-5-O2 13.0 .sub. [1 kHz, 20 C.]: 12.2 CPTY-3-O2 12.0 .sub. [1 kHz, 20 C.]: 9.5 CPTY-5-O2 5.0 [1 kHz, 20 C.]: 2.8 PPTUI-3-2 14.0 K.sub.1 [pN, 20 C.]: 17.3 CP-3-O1 14.0 K.sub.3 [pN, 20 C.]: 22.1 CP-3-O2 8.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.27 100.0 V.sub.0 [V, 20 C.]: 2.65

[0361] The crossover frequency f.sub.CO of this mixture is 6.0 kHz.

TABLE-US-00013 Mixture Example 6 Compound weight % Physical properties CPZG-5-N 15.0 T(N, I) [ C.]: 109.5 B(S)-2O-O4 6.0 n.sub.e [589 nm, 20 C.]: 1.7273 B(S)-2O-O5 6.0 n.sub.o [589 nm, 20 C.]: 1.5046 B(S)-2O-O6 5.0 n [589 nm, 20 C.]: 0.2227 COB(S)-2-O4 8.0 .sub. [1 kHz, 20 C.]: 12.9 PTY-5-O2 12.0 .sub. [1 kHz, 20 C.]: 9.6 CPTY-3-O2 10.0 [1 kHz, 20 C.]: 3.3 PPTUI-3-2 16.0 K.sub.1 [pN, 20 C.]: 16.9 CP-3-O1 14.0 K.sub.3 [pN, 20 C.]: 19.6 CP-3-O2 8.0 K.sub.3/K.sub.1 [pN, 20 C.]: 1.16 100.0 V.sub.0 [V, 20 C.]: 2.39

[0362] The crossover frequency f.sub.CO of this mixture is 6.0 kHz.