LIQUID-CRYSTALLINE MEDIUM

Abstract

The present invention relates to liquid-crystalline media comprising one or more compounds selected from the group of compounds of formula I

##STR00001##

in which the parameters have the meaning indicated in Claim 1, and to components comprising these media for high-frequency technology, in particular phase shifters and microwave array antennas.

Claims

1. Liquid-crystal medium, characterised in that it comprises one or more compounds of formula AN ##STR00261## in which R.sup.1 denotes alkyl or alkenyl having up to 15 C atoms, ##STR00262##  on each occurrence, independently of one another, denote ##STR00263##  alternatively denotes ##STR00264## L.sup.1 and L.sup.2 independently from one another, denote H or F, and n is 0, 1 or 2.

2. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more compounds selected from the group of compounds of the formulae AN-1 and AN-2 ##STR00265## in which the occurring groups and parameters have the meanings given in claim 1 for formula AN.

3. Liquid-crystal medium according to claim 2, characterised in that it comprises one or more compounds of formula AN-2 as indicated in claim 2, in which R.sup.2 denotes alkylen having up to 7 C atoms and n is 0.

4. Liquid-crystal medium according to claim 1, characterised in that it additionally comprises one or more compounds selected from the group of compounds of formula I ##STR00266## in which R.sup.1 denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, n is 0, 1 or 2, and ##STR00267##  independently of one another, denote ##STR00268##  where ##STR00269##  alternatively denotes ##STR00270##

5. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more compounds selected from the group of compounds of the formulae II and III ##STR00271## in which R.sup.2 denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, Z.sup.21 denotes trans-CH═CH—, trans-CF═CF— or —C≡C—, ##STR00272##  independently of one another, denote ##STR00273## R.sup.3 has the meaning given for R.sup.2 above, one of Z.sup.31 and Z.sup.32 denotes trans-CH═CH—, trans-CF═CF— or —C≡C—, and the other one of Z.sup.31 and Z.sup.32 denotes trans-CH═CH—, trans-CF═CF— or a single bond, ##STR00274##  independently of one another, denote ##STR00275##  alternatively independently denotes ##STR00276##

6. Medium according to claim 1, characterised in that it comprises one or more compounds of formula VI-5 ##STR00277## in which R.sup.61 denotes H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, C atoms, X.sup.62 denotes F or Cl, —CN, SF.sub.5, fluorinated alkyl or alkoxy having 1 to 7 C atoms or fluorinated alkenyl, alkenyloxy or alkoxyalkyl having 2 to 7 C atoms, ##STR00278##  independently of one another, denote ##STR00279##

7. Medium according to claim 1, characterised in that it comprises one or more compounds of formula AN, as indicated in claim 1, in a total concentration in the range of from 5% to 100%.

8. Medium according to claim 2, characterised in that it comprises one or more compounds of formula AN-2, as indicated in claim 2, in a total concentration of 5% or more.

9. A ended Medium according to claim 1, characterised in that it additionally comprises one or more chiral compounds.

10. Component for high-frequency technology, characterised in that it comprises a liquid crystal medium according to claim 1.

11. Component according to claim 10, where the component is suitable for operation in the microwave range.

12. Component according to claim 10, where the component is a phase shifter or an LC based antenna element operable in the microwave region.

13. A method which comprises including a liquid-crystal medium according to claim 1 in a component for high-frequency technology.

14. Process for the preparation of a liquid-crystal medium, characterised in that one or more compounds of formula AN are mixed with one or more compounds of formula AN or additional mesogenic compounds and optionally a chiral compound is added.

15. Microwave antenna array, characterised in that it comprises one or more components according to claim 10.

Description

EXAMPLES

[0433] The following examples illustrate the present invention without limiting it in any way.

[0434] However, it is clear to the person skilled in the art from the physical properties 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

[0435] Liquid-crystal mixtures M-1 and M-2 having the composition and properties as indicated in the following tables are prepared and characterized with respect to their general physical properties and their applicability in microwave components at 19 GHz.

Mixture Example M-1

[0436]

TABLE-US-00007 Composition Compound Conc. No Abbreviation [mass-%] Physical Properties 1 PU-3-AN  5.0 T (N, I) [° C.] = 114 2 PU-5-AN  5.0 ε.sub.|| (20° C., 1 kHz) = 38.9 3 PG-3-AN  20.0 Δε (20° C., 1 kHz) = 32.9 4 CP-1V-AN  10.0 γ.sub.1 (20° C.)/mPa .Math. s = 324 5 CP-V-AN  20.0 K.sub.1 [pN] = 11.9 6 CP-4-AN  20.0 K.sub.3 [pN] = 33.6 7 CP-V2-AN  20.0 V.sub.0 [V] = 0.64 Σ 100.0 tan δ.sub.εr, ⊥ (20° C., = 0.0312 19 GHz) tan δ.sub.εr, | | (20° C., = 0.0088 19 GHz) τ (20° C., 19 GHz) = 0.186 ε.sub.r, | | (20° C., 19 GHz) = 3.1800 ε.sub.r, ⊥ (20° C., 19 GHz) = 2.5870 η (20° C., 19 GHz) = 6.0

[0437] This mixture is very well suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the micro wave (MW) region.

Mixture Example M-2

[0438]

TABLE-US-00008 Composition Compound Conc. No Abbreviation [mass-%] Physical Properties 1 PTU-3-S  10.0 T (N, I) [° C.] = 121.5 2 PTU-5-S  10.0 ε.sub.|| (20° C., 1 kHz) = 27.8 3 PGU-3-S  16.0 Δε (20° C., 1 kHz) = 23.1 4 PPTU-4-S  5.0 γ.sub.1 (20° C.)/mPa.Math. s = 502 5 PPTU-5-S  5.0 K.sub.1 [pN] = 12.8 6 CPU-2-S  18.0 K.sub.3 [pN] = 18.6 7 CPU-4-S  18.0 V.sub.0 [V] = 0.78 8 CP-V2-AN  12.0 9 PTU-V2-OT  6.0 tan δ.sub.εr, ⊥ (20° C., = 0.0114 Σ 100.0 19 GHz) tan δ.sub.εr, | | (20° C., = 0.0058 19 GHz) τ (20° C., 19 GHz) = 0.258 ε.sub.r, | | (20° C., 19 GHz) = 3.3471 ε.sub.r, ⊥ (20° C., 19 GHz) = 2.4846 η (20° C., 19 GHz) = 22.6

[0439] This mixture is very well suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the micro wave (MW) region.

[0440] In addition, for comparison the properties of the compound n-1-pentyl-4′-cyanobiphenyl (also called PP-5-N or CB15, Comparative Example C-1) and the liquid-crystal mixture ZLI-4792 (product from Merck KGaA, Darmstadt, Germany, Comparative Example C-2) were investigated at 19 GHz.

[0441] In the following table 1, the application-relevant properties of the comparative Examples C-1 and C-2, measured at 20° C. and 19 GHz, unless indicated otherwise, are summarised in comparison with the corresponding values of the mixture examples M-1 and M-2.

TABLE-US-00009 TABLE 1 Example Δε .sup..star-solid. ε.sub.r,∥ ε.sub.r,⊥ τ tan δ.sub.ε.sub.r,Max. η C-1 20.1 3.06 2.66 0.131 0.0273 4.8 C-2 5.2 2.57 2.29 0.107 0.0126 8.5 M-1 32.9 3.1800 2.5870 0.186 0.0312 6.0 M-2 23.1 3.3471 2.4846 0.258 0.0114 22.6 .sup..star-solid. measured at 1 kHz

[0442] As can be seen from the values given in table 1, the comparative example C-1 has a high dielectric anisotropy but a very high dielectric loss and, therefore a very low figure-of-merit. The comparative example C-2 is a commercial mixture with an acceptable figure of merit, but with a comparatively low dielectric anisotropy. On the contrary, surprisingly the mixture examples M-1 and M-2 according to the present invention exhibit a very high dielectric anisotropy and low threshold voltage resulting in very good switching behaviour and low switching voltages of a device, while showing high tunability, low dielectric loss and high figures-of-merit.