Liquid-crystalline medium and high-frequency components comprising same

Abstract

The present invention relates to liquid-crystalline media comprising one or more chiral compounds and one or more compounds selected from the group of compounds of formulae I, II and III,

##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 chiral, preferably mesogenic, compounds one or more compounds selected from the group of compounds of formulae I, II and III ##STR00225## in which L.sup.11 denotes R.sup.11 or X.sup.11, L.sup.12 denotes R.sup.12 or X.sup.12, R.sup.11 and R.sup.12, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 15 C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15 C atoms, X.sup.11 and X.sup.12, independently of one another, denote H, F, Cl, CN, NCS, SF.sub.5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7 C atoms, and ##STR00226## to ##STR00227## independently of one another, denote ##STR00228## in which L.sup.21 denotes R.sup.21 and, in the case where Z.sup.21 and/or Z.sup.22 denote trans-CHCH or trans-CFCF, alternatively denotes X.sup.21, L.sup.22 denotes R.sup.22 and, in the case where Z.sup.21 and/or Z.sup.22 denote trans-CHCH or trans-CFCF, alternatively denotes X.sup.22, R.sup.21 and R.sup.22, independently of one another, denote H, unfluorinated alkyl or unfluorinated alkoxy having 1 to 17, preferably having 3 to 10, C atoms or unfluorinated alkenyl, unfluorinated alkenyloxy or unfluorinated alkoxyalkyl having 2 to 15, preferably 3 to 10, C atoms, X.sup.21 and X.sup.22, independently of one another, denote F or Cl, CN, NCS, SF.sub.5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, fluorinated alkenyloxy or fluorinated alkoxyalkyl having 2 to 7 C atoms, one of Z.sup.21 and Z.sup.22 denotes trans-CHCH, trans-CFCF or CC and the other, independently thereof, denotes trans-CHCH, trans-CFCF or a single bond, and ##STR00229## to ##STR00230## independently of one another, denote ##STR00231## in which L.sup.31 denotes R.sup.31 or X.sup.31, L.sup.32 denotes R.sup.32 or X.sup.32, R.sup.31 and R.sup.32, independently of one another, denote 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.31 and X.sup.32, independently of one another, denote H, F, Cl, CN, NCS, SF.sub.5, fluorinated alkyl or fluorinated alkoxy having 1 to 7 C atoms or fluorinated alkenyl, unfluorinated or fluorinated alkenyloxy or unfluorinated or fluorinated alkoxyalkyl having 2 to 7 C atoms, Z.sup.31 to Z.sup.33, independently of one another, denote trans-CHCH, trans CFCF, CC or a single bond, and ##STR00232## to ##STR00233## independently of one another, denote ##STR00234## and optionally one or more polymerisable, preferably mesogenic, compounds preferably of formula P
P.sup.a(Sp.sup.a).sub.s1-(A.sup.1-Z.sup.1).sub.n1-A.sup.2-Q-A.sup.3-(Z.sup.4-A.sup.4).sub.n2-(Sp.sup.b).sub.s2P.sup.bP wherein the individual radicals have the following meanings: P.sup.a P.sup.b each, independently of one another, are a polymerisable group, Sp.sup.a, Sp.sup.b each, independently of one another, denote a spacer group, s1, s2 each, independently of one another, denote 0 or 1, n1, n2 each, independently of one another, denote 0 or 1, preferably 0, Q denotes a single bond, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, (CO)O, O(CO), (CH.sub.2).sub.4, CH.sub.2CH.sub.2, CF.sub.2CF.sub.2, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CHCH, CFCF, CFCH, (CH.sub.2).sub.3O, O(CH.sub.2).sub.3, CHCF, CC, O, CH.sub.2, (CH.sub.2).sub.3, CF.sub.2, preferably CF.sub.2O, Z.sup.1, Z.sup.4 denote a single bond, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, (CO)O, O(CO), (CH.sub.2).sub.4, CH.sub.2CH.sub.2, CF.sub.2CF.sub.2, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CHCH, CFCF, CFCH, (CH.sub.2).sub.3O, O(CH.sub.2).sub.3, CHCF, CC, O, CH.sub.2, (CH.sub.2).sub.3, CF.sub.2, where Z.sup.1 and Q or Z.sup.4 and Q do not simultaneously denote a group selected from CF.sub.2O and OCF.sub.2, A.sup.1, A.sup.2, A.sup.3, A.sup.4 each, independently of one another, denote a diradical group selected from the following groups: a) the group consisting of trans-1,4-cyclohexylene, 1,4-cyclohexenylene and 1,4-bicyclohexylene, in which, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S and in which, in addition, one or more H atoms may be replaced by F, b) the group consisting of 1,4-phenylene and 1,3-phenylene, in which, in addition, one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by L, c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by L, d) the group consisting of saturated, partially unsaturated or fully unsaturated, and optionally substituted, polycyclic radicals having 5 to 20 cyclic C atoms, one or more of which may, in addition, be replaced by heteroatoms, preferably selected from the group consisting of bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl, spiro[3.3]heptane-2,6-diyl, ##STR00235## where, in addition, one or more H atoms in these radicals may be replaced by L, and/or one or more double bonds may be replaced by single bonds, and/or one or more CH groups may be replaced by N, and A.sup.3, alternatively may be a single bond, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, R.sup.03, R.sup.04 each, independently of one another, denote H, F or straight-chain or branched alkyl having 1 to 12 C atoms, in which, in addition, one or more H atoms may be replaced by F, M denotes O, S, CH.sub.2, CHY.sup.1 or CY.sup.1Y.sup.2, and Y.sup.1 and Y.sup.2 each, independently of one another, have one of the meanings indicated above for R.sup.0, or denote Cl or CN, and one of the groups Y.sup.1 and Y.sup.2 alternatively denotes OCF.sub.3, preferably H, F, Cl, CN or CF.sub.3.

2. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more chiral compounds having an absolute value of the HTP of 10 m or more.

3. Liquid-crystal medium according to claim 2, characterised in that it comprises one or more chiral compounds selected from the group of compounds of formulae A-I to A-VI: ##STR00236## including the (R,S), (S,R), (R,R) and (S,S) enantiomers, which are not shown, ##STR00237## in which R.sup.a11 and R.sup.a12, independently of one another, are alkyl, oxaalkyl or alkenyl having from 2 to 9 carbon atoms, and R.sup.a11 is alternatively methyl or alkoxy having from 1 to 9 carbon atoms, R.sup.a21 and R.sup.a22, independently of one another, are alkyl or alkoxy having from 1 to 9 carbon atoms, oxaalkyl, alkenyl or alkenyloxy having from 2 to 9 carbon atoms, R.sup.a31 and R.sup.a32, independently of one another, are alkyl, oxaalkyl or alkenyl having from 2 to 9 carbon atoms, and R.sup.a11 is alternatively methyl or alkoxy having from 1 to 9 carbon atoms, ##STR00238## is ##STR00239## are each, independently of one another, 1,4-phenylene, which may also be mono-, di- or trisubstituted by L, or 1,4-cyclohexylene, L is H, F, Cl, CN or optionally halogenated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkoxycarbonyloxy having 1-7 carbon atoms, c is 0 or 1, Z.sup.0 is COO, OCO, CH.sub.2CH.sub.2 or a single bond, and R.sup.0 is alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkylcarbonyloxy having 1-12 carbon atoms. X.sup.1, X.sup.2, Y.sup.1 and Y.sup.2 are each, independently of one another, F, Cl, Br, I, CN, SCN, SF.sub.5, straight-chain or branched alkyl having from 1 to 25 carbon atoms, which may be monosubstituted or polysubstituted by F, Cl, Br, I or CN and in which, in addition, one or more non-adjacent CH.sub.2 groups may each, independently of one another, be replaced by O, S, NH, NR.sup.0, CO, COO, OCO, OCOO, SCO, COS, CHCH or CC in such a way that O and/or S atoms are not bonded directly to one another, a polymerisable group or cycloalkyl or aryl having up to 20 carbon atoms, which may optionally be monosubstituted or polysubstituted by halogen or by a polymerisable group, x.sup.1 and x.sup.2 are each, independently of one another, 0, 1 or 2, y.sup.1 and y.sup.2 are each, independently of one another, 0, 1, 2, 3 or 4, B.sup.1 and B.sup.2 are each, independently of one another, an aromatic or partially or fully saturated aliphatic six-membered ring in which one or more CH groups may be replaced by N atoms and one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S, W.sup.1 and W.sup.2 are each, independently of one another, Z.sup.1-A.sup.1-(Z.sup.2-A.sup.2).sub.m-R, and one of the two is alternatively R.sup.1 or A.sup.3, but both are not simultaneously H, or ##STR00240## is ##STR00241## U.sup.1 and U.sup.2 are each, independently of one another, CH.sub.2, O, S, CO or CS, V.sup.1 and V.sup.2 are each, independently of one another, (CH.sub.2).sub.n, in which from one to four non-adjacent CH.sub.2 groups may be replaced by O and/or S, and one of V.sup.1 and V.sup.2 and, in the case where ##STR00242## is ##STR00243## both are a single bond, Z.sup.1 and Z.sup.2 are each, independently of one another, O, S, CO, COO, OCO, OCOO, CONR.sup.0, NR.sup.0CO, OCH.sub.2, CH.sub.2O, SCH.sub.2, CH.sub.2S, CF.sub.2O, OCF.sub.2, CF.sub.2S, SCF.sub.2, CH.sub.2CH.sub.2, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CF.sub.2CF.sub.2, CHN, NCH, NN, CHCH, CFCH, CHCF, CFCF, CC, a combination of two of these groups, where no two O and/or S and/or N atoms are bonded directly to one another, or a single bond, A.sup.1, A.sup.2 and A.sup.3 are each, independently of one another, 1,4-phenylene, in which one or two non-adjacent CH groups may be replaced by N, 1,4-cyclohexylene, in which one or two non-adjacent CH.sub.2 groups may be replaced by O and/or S, 1,3-dioxolane-4,5-diyl, 1,4-cyclohexenylene, 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, where each of these groups may be monosubstituted or polysubstituted by L, and in addition A.sup.1 is a single bond, L is a halogen atom, CN, NO.sub.2, alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl or alkoxycarbonyloxy having 1-7 carbon atoms, in which one or more H atoms may be replaced by F or Cl, m is in each case, independently, 0, 1, 2 or 3, and R and R.sup.1 are each, independently of one another, H, F, Cl, Br, I, CN, SCN, SF.sub.5, straight-chain or branched alkyl having from 1 or 3 to 25 carbon atoms respectively, which may optionally be monosubstituted or polysubstituted by F, Cl, Br, I or CN, and in which one or more non-adjacent CH.sub.2 groups may be replaced by O, S, NH, NR.sup.0, CO, COO, OCO, OCOO, SCO, COS, CHCH or CC, where no two O and/or S atoms are bonded directly to one another, or a polymerisable group.

4. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more compounds of the formula I, as indicated in claim 1.

5. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more compounds of the formula II, as indicated in claim 1.

6. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more compounds of the formula III, as indicated in claim 1.

7. Liquid-crystal medium according to claim 1, characterised in that it additionally comprises a polymerisation initiator.

8. Method of improving the response time of a liquid-crystal medium according to claim 1 by using one or more chiral compounds.

9. Composite system comprising a polymer obtained or obtainable from the polymerisation of the polymerisable compounds according to claim 1, and a liquid-crystal medium comprising one or more compounds selected from the group of compounds of formulae I to III, as specified in claim 1.

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

11. The component according to claim 10, wherein said component is suitable for operation in the microwave range.

12. The component according to claim 10, wherein said component is a phase shifter or a LC based antenna element operable in the microwave region.

13. (canceled)

14. A process for the preparation of a liquid-crystal medium, said process comprising: mixing one or more polymerisable compounds with one or more compounds selected from the group of the compounds of formulae I, II and III, according to claim 1, and optionally with one or more further compounds and/or with one or more additives.

15. A microwave antenna array comprising one or more components according to claim 10.

16. Component for high-frequency technology, characterised in that said component comprises a composite system according to claim 9.

Description

EXAMPLES

[0485] The following examples illustrate the present invention without limiting it in any way.

[0486] 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.

Examples 1.1 to 1.10 and Comparative Example 1

Comparative Example 1

[0487] A liquid-crystal mixture C-1 having the composition and properties as indicated in the following table is prepared and characterized with respect to its general physical properties and its applicability in microwave components at 19 GHz.

TABLE-US-00007 Composition Compound Conc./ No. Abbreviation mass-% 1 PPTUI-3-2 20.0 2 PPTUI-3-4 36.0 3 GGP-3-CL 10.0 4 GGP-5-CL 20.0 5 CPGP-5-2 7.0 6 CPGP-5-3 7.0 100.0 Physical Properties T(N, I) = 173 C. n(20 C., 589.3 nm) = 0.335 (20 C., 1 kHz) = 4.6 .sub.1 (20 C.) = 746 mPa .Math. s tan .sub. r, (20 C., 19 GHz) = 0.0143 tan .sub. r, (20 C., 19 GHz) = 0.0038 (20 C., 19 GHz) = 0.252 (20 C., 19 GHz) = 17.6

[0488] This mixture is suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the micro wave (MW) region. In comparison to the Examples 1.1 and 1.2 this mixture clearly exhibits inferior response times.

Examples 1.1 and 1.2

[0489] The mixture C-1 is divided into three parts. To each one of these two parts a certain concentration of the chiral dopant S-2011 as shown in table F above, having a negative value of the HTP, is added.

[0490] To one each of these two parts alternatively 0.05% of S-2011 and 0.20% of S-2011 are added, respectively.

[0491] The two resultant mixtures are called M-1.1 and M-1.2. These two mixtures each are filled into test cells with antiparallel rubbed glass substrates covered by PI AI3046. The test cells have a cell gap of 50 m.

TABLE-US-00008 TABLE 1 Compositions of the mixtures investigated Material C-1 S-2011 Example Mixture Composition Number Concentration/mass-% C-1 100.00 0.00 1.1 99.95 0.05 1.2 99.80 0.20

TABLE-US-00009 TABLE 2 Physical Properties (at 20 C.) of the mixtures investigated Mixture C-1 M-1.1 M-1.2 Property Value T(N, I)/ C. 173 t.b.d. t.b.d. n(20 C., 589.3 nm) 0.335 t.b.d. t.b.d. (20 C., 1 kHz) 4.6 t.b.d. t.b.d. .sub.1 (20 C.)/mPa .Math. s 746 t.b.d. t.b.d. V.sub.0/V t.b.d. t.b.d. t.b.d. Remarks: t.b.d.: to be determined V.sub.0 in 50 um test cell, described above.

TABLE-US-00010 TABLE 3 Microwave characteristics and response times (at 20 C.) of the mixtures investigated Mixture C-1 M-1.1 M-1.2 Property Value tan .sub. r, (20 C., 19 GHz) 0.0143 t.b.d. t.b.d. tan .sub. r, (20 C., 19 GHz) 0.0038 t.b.d. t.b.d. (20 C., 19 GHz) 0.252 t.b.d. t.b.d. (20 C., 19 GHz) 17.6 t.b.d. t.b.d. .sub.on/ms t.b.d. t.b.d. t.b.d. .sub.off/ms t.b.d. 320 230 .sub.sum/ms t.b.d. t.b.d. t.b.d. Remarks: t.b.d.: to be determined and n.a.: not applicable.

[0492] These two mixtures are very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the micro wave (MW) region. Additionally in comparison to the Examples 1.1 and 1.2 these mixtures clearly exhibit superior, i.e. significantly smaller, response times. Mixture M-1.2, which comprising the higher concentration of the chiral compound compared to M-1.1, has an even more improved response behaviour.

[0493] The switching times are determined from the electro-optical response in test cells with antiparallel rubbed orientation layers, having a cell gap of 50 m, in using an DMS 301 measuring instrument (Autronic Melcher, Germany) at an operating voltage in the range from 20-30 V

[0494] The response times or switching on and for switching off are determined for the time required to change the relative transmission from 10% to 90% and vice versa, respectively.

.sub.ont(10%)t(90%)

.sub.offt(90%)t(10%)

Examples 1.3 to 1.6

[0495] The mixture C-1 is again prepared and divided into four parts. To each one of these four parts a certain concentration again of the chiral dopant S-5011 HTP is added.

[0496] To one each of these two parts alternatively 0.1%, 0.3%, 0.5% and 1.0%, respectively of S-2011 are added.

[0497] The four resultant mixtures are called M-1.3 to M-1.6. These four mixtures investigated with respect to their performance in microwave applications.

TABLE-US-00011 TABLE 4 Compositions of the mixtures investigated Material C-1 S-2011 Example Mixture Composition Number Concentration/mass-% C-1 100.00 0.00 1.3 99.90 0.10 1.4 99.70 0.30 1.5 99.50 0.50 1.6 99.00 1.00

TABLE-US-00012 TABLE 5 Physical Properties (at 20 C.) of the mixtures investigated Mixture C-1 M-1.3 M-1.4 M-1.5 M-1.6 Property Value T(N, I)/ C. 172.7* 172.6 172.3 172.1 171.5 n(20 C., 589.3 nm) 0.335 t.b.d. t.b.d. t.b.d. t.b.d. (20 C., 1 kHz) 4.6 t.b.d. t.b.d. t.b.d. t.b.d. .sub.1 (20 C.)/mPa .Math. s 746 t.b.d. t.b.d. t.b.d. t.b.d. V.sub.0/V t.b.d. t.b.d. t.b.d. t.b.d. t.b.d. Remarks: *re-measured here t.b.d.: to be determined V.sub.0 in 50 m test cell, described above.

TABLE-US-00013 TABLE 6 Microwave characteristics and response times (at 20 C.) of the mixtures investigated Mixture C-1* M-1.3 M-1.4 M-1.5 M-1.6 Property Value tan .sub. .sub.r, (20 C., 0.0136* 0.0138 0.0103 0.0107 0.0108 19 GHz) tan .sub. .sub.r, (20 C., 0.0038* t.b.d. t.b.d. t.b.d. t.b.d. 19 GHz) (20 C., 19 GHz) 0.247* 0.245 t.b.d. t.b.d. t.b.d. (20 C., 19 GHz) 18.2* 17.8 t.b.d. t.b.d. t.b.d. .sub.on/ms t.b.d. t.b.d. t.b.d. t.b.d. t.b.d. .sub.off/ms t.b.d. 320 230 t.b.d. t.b.d. .sub.sum/ms t.b.d. t.b.d. t.b.d. t.b.d. t.b.d. Remarks: *): re-measured here t.b.d.: to be determined and n.a.: not applicable.

[0498] Remarkably, the dielectric loss of the materials is reduced by increased concentration of the chiral dopant.

Examples 1.7 to 1.10

[0499] The mixture C-1 is again prepared and again divided into four parts. To each one of these four parts a certain concentration now of the chiral dopant R-5011 (also Merck KGaA) as shown in table F above, having a positive value of the HTP and high value at the same time, is added.

[0500] To one each of these two parts alternatively 0.1%, 0.3%, 0.5% and 1.0%, respectively of R-5011 are added.

[0501] The four resultant mixtures are called M-1.7 to M-1.10. These four mixtures investigated with respect to their performance in microwave applications.

TABLE-US-00014 TABLE 7 Compositions of the mixtures investigated Material C-1 R-5011 Example Mixture Composition Number Concentration/mass-% C-1 100.00 0.00 1.7 99.90 0.10 1.8 99.70 0.30 1.9 99.50 0.50 1.10 99.00 1.00

TABLE-US-00015 TABLE 8 Physical Properties (at 20 C.) of the mixtures investigated Mixture C-1 M-1.7 M-1.8 M-1.9 M-1.10 Property Value T(N, I)/ C. 172.7* 172.4 172.2 172.1 171.1 n(20 C., 589.3 nm) 0.335 t.b.d. t.b.d. t.b.d. t.b.d. (20 C., 1 kHz) 4.6 t.b.d. t.b.d. t.b.d. t.b.d. .sub.1 (20 C.)/mPa .Math. s 746 t.b.d. t.b.d. t.b.d. t.b.d. V.sub.0/V t.b.d. t.b.d. t.b.d. t.b.d. t.b.d. Remarks: *): re-measured here t.b.d.: to be determined V.sub.0 in 50 m test cell, described above.

TABLE-US-00016 TABLE 9 Microwave characteristics and response times (at 20 C.) of the mixtures investigated Mixture C-1 M-1.7 M-1.8 M-1.9 M-1.10 Property Value tan .sub. .sub.r, (20 C., 19 GHz) 0.0136* 0.0106 0.0105 0.0105 0.0105 tan .sub. .sub.r, (20 C., 19 GHz) 0.0038* t.b.d. t.b.d. t.b.d. t.b.d. (20 C., 19 GHz) 0.247* t.b.d. t.b.d. t.b.d. t.b.d. (20 C., 19 GHz) 18.2* t.b.d. t.b.d. t.b.d. t.b.d. .sub.on/ms t.b.d. t.b.d. t.b.d. t.b.d. t.b.d. .sub.off/ms t.b.d. 320 230 .sub.sum/ms t.b.d. t.b.d. t.b.d. Remarks: *): re-measured here t.b.d.: to be determined and n.a.: not applicable.

[0502] Strikingly, also here, like in examples 1.3 to 1.6, the dielectric loss of the materials is reduced by increased concentration of the chiral dopant.

[0503] It has to be noticed here, however, that the positive HTP of R-5011 is about five times that of the absolute value of S.2011. Consequently the samples having the a given concentration of the chiral dopant R-5011 are much more densely twisted than those comprising the same concentration of S-2011. As a first approximation, the sample comprising 0.1% of R-5011 is twisted to almost the same pitch like the sample with 0.5% of S-2011. Only the twisting sense is reversed. The same approximate relation would holds for a sample comprising 0.2% of R-5011, i.e. the concentration in the exact middle between those of mixture M-1.7 and M-1.8 and Mixture M-1.6 comprising 1.0% of S-2011.

Comparative Example 2

[0504] For comparison, the well known compound 4-pentyl-4-cyanobiphenyl (also called 5CB or K15, Merck KGaA) gives tan .sub.r,=0.026 and =4.3 at 20 C.

TABLE-US-00017 TABLE 10 Comparison of the properties at 19 GHz and 20 C. Example Liquid crystal .sub.r .sub.r, 1 M-1 0.56 0.013 14.5 Comparison 5CB 0.026 4.3

Example 2

[0505] A liquid-crystal mixture M-2 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00018 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 170.1 C. 1 GGP-3-CL 10.0 n.sub.e (20 C., 589.3 nm) = 1.5267 2 GGP-5-CL 20.0 n (20 C., 589.3 nm) = 0.2918 3 PPTUI-3-2 20.0 .sub. (20 C., 1 kHz) = 7.8 4 PPTUI-3-4 20.0 (20 C., 1 kHz) = 4.4 5 PPTUI-4-4 16.0 .sub.1 (20 C.) = 698 mPa .Math. s 6 CPGP-5-2 7.0 7 CPGP-5-3 7.0 100.0

[0506] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the MW region.

Example 3

[0507] A liquid-crystal mixture M-3 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00019 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 183.5 C. 1 GGP-3-CL 10.0 n (20 C., 589.3 nm) = 0.283 2 GGP-5-CL 19.0 .sub. (20 C., 1 kHz) = 8.0 3 PPTUI-3-2 18.0 (20 C., 1 kHz) = 3.5 4 PPTUI-3-4 18.0 .sub.1 (20 C.) = 753 mPa .Math. s 5 PPTUI-4-4 10.0 6 PGIGP-3-5 6.00 7 PPGU-3-F 3.00 8 CPGP-5-2 8.0 9 CPGP-5-3 8.0 100.0

[0508] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters.

Example 4

[0509] A liquid-crystal mixture M-4 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00020 Composition Physical properties hz Compound No. Abbreviation T(N,I) >200 C. 1 GGP-3-CL 10.0 2 GGP-5-CL 17.0 3 PPTUI-3-2 13.0 4 PPTUI-3-4 13.0 5 PPTUI-4-4 10.0 6 PPGU-3-F 3.0 7 PPGU-4-F 3.0 8 PPGU-V2-F 3.0 9 PGIGP-3-5 7.0 10 PGIGP-5-5 7.0 11 CPGP-5-2 7.0 12 CPGP-5-3 7.0 100.0

[0510] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the MW region.

Example 5

[0511] A liquid-crystal mixture M-5 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00021 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 134.5 C. 1 GGP-3-F 10.0 n.sub.e (20 C., 589.3 nm) = 1.8036 2 GGP-5-F 10.0 n (20 C., 589.3 nm) = 0.2774 3 GGP-3-CL 10.0 .sub. (20 C., 1 kHz) = 15.2 4 GGP-4-CL 20.0 (20 C., 1 kHz) = 10.2 5 GGP-5-CL 20.0 .sub.1 (20 C.) = 758 mPa .Math. s 6 GGP-6-CL 10.0 7 GGPP-5-3 5.0 8 PGGP-3-5 5.0 9 PGGP-3-6 5.0 10 PGGP-5-3 5.0 100.0

[0512] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the MW region.

Example 6

[0513] A liquid-crystal mixture M-6 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00022 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 134.7 C. 1 GGP-3-F 5.0 n.sub.e (20 C., 589.3 nm) = 1.7885 2 GGP-3-CL 10.0 n (20 C., 589.3 nm) = 0.2640 3 GGP-4-CL 10.0 .sub. (20 C., 1 kHz) = 8.8 4 GGP-5-CL 15.0 (20 C., 1 kHz) = 4.7 5 GGP-5-3 20.0 .sub.1 (20 C.) = 660 mPa .Math. s 6 PGP-2-5 10.0 7 PGP-3-7 15.0 8 PGP-2-2V 10.0 9 PGGP-3-5 5.0 100.0

[0514] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the MW region.

Example 7

[0515] A liquid-crystal mixture M-7 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00023 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 124.5 C. 1 GGP-3-CL 10.0 n.sub.e (20 C., 589.3 nm) = 1.7951 2 GGP-4-CL 20.0 n (20 C., 589.3 nm) = 0.2709 3 GGP-5-CL 20.0 .sub. (20 C., 1 kHz) = 11.6 4 GGP-6-CL 10.0 (20 C., 1 kHz) = 6.8 5 GGP-5-3 25.0 .sub.1 (20 C.) = 895 mPa .Math. s 6 PGGP-3-5 5.0 7 PGGP-3-6 5.0 8 PGGP-5-3 5.0 100.0

[0516] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the MW region.

Example 8

[0517] A liquid-crystal mixture M-8 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00024 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 184.5 C. 1 GGP-3-CL 5.0 2 GGP-5-CL 19.0 3 PGU-7-F 2.0 4 PPTUI-3-2 18.0 5 PPTUI-3-4 18.0 6 PPTUI-4-4 10.0 7 PPGU-7-F 2.0 8 PGIGP-3-5 6.0 9 DPGU-3-F 2.0 10 DPGU-3-OT 2.0 11 CPGP-5-2 8.0 12 CPGP-5-3 8.0 100.0

TABLE-US-00025 TABLE 11 Properties of mixture M-8 at 30 GHz T/ C. .sub.r, .sub.r,|| tan .sub. r, tan .sub. r,|| .sub. r 9.47 2.51 2.92 0.0094 0.0035 0.140 15.0 19.67 2.51 2.92 0.0115 0.0041 0.139 12.1 30.07 2.49 2.94 0.0135 0.0046 0.152 11.2 40.52 2.44 2.96 0.0169 0.0046 0.175 10.3 50.17 2.36 2.96 0.0214 0.0050 0.204 9.48 59.99 2.34 2.94 0.0246 0.0056 0.204 8.24 70.41 2.34 2.93 0.0276 0.0061 0.199 7.22 79.74 2.35 2.91 0.0291 0.0067 0.195 6.69 84.52 2.35 2.91 0.0295 0.0071 0.192 6.51 Note: at 20 C., the following is obtained approximately by intrapolation: .sub.r = 2.51, tan .sub. r, = 0.0115, .sub. r = 0.140 and = 14.5.

[0518] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters or LC based antenna elements in the MW region.

Example 9

[0519] A liquid-crystal mixture M-9 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00026 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 178 C. 1 GGP-5-CL 10.0 2 GGP-6-CL 5.0 3 PGP-3-2V 3.0 4 PGP-2-2V 3.0 5 PPTUI-3-2 15.0 6 PPTUI-3-4 18.0 7 PPTUI-4-4 21.0 8 PPGU-7-F 2.0 9 PPGU-V2-F 2.0 10 PGIGP-3-5 7.0 11 CPTP-3-2 4.0 12 CPGU-3-OT 2.0 13 CPGU-4-OT 2.0 14 DPGU-3-OT 2.0 15 CPGP-5-2 4.0 100.0

[0520] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters and for antenna elements.

Example 10

[0521] A liquid-crystal mixture M-10 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00027 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 159.5 C. 1 GGP-5-CL 20.0 .sub. (20 C., 1 kHz) = 7.9 2 GGP-5-3 12.0 (20 C., 1 kHz) = 4.3 3 PPTUI-3-2 12.0 .sub.1 (20 C.) = 686 mPa .Math. s 4 PPTUI-3-4 16.0 5 PPTUI-4-4 20.0 6 PGUQU-5-F 5.0 7 PGGP-3-5 5.0 8 PGGP-3-6 4.0 9 APGP-3-3 3.0 10 APGP-3-4 3.0 100.0

[0522] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters and for antenna elements.

Example 11

[0523] A liquid-crystal mixture M-11 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00028 Composition Physical properties hz Compound No. Abbreviation T(N,I) = 169 C. 1 GGP-5-3 10.0 2 PPTUI-3-F 8.0 3 PPTUI-4-F 8.0 4 PPTUI-3-2 12.0 5 PPTUI-3-4 16.0 6 PPTUI-4-4 20.0 7 PPTUI-3-A4 5.0 8 PGUQU-5-F 7.0 9 PGGP-3-5 4.0 10 PGGP-3-6 4.0 11 APGP-3-3 3.0 12 APGP-3-4 3.0 100.0

[0524] This mixture is very highly suitable for applications in the microwave range, in particular for phase shifters and for antenna elements.

[0525] The mixtures of examples 2 to 11 are treated and investigated as described under example 1. The resultant mixtures comprising the chiral compound in the respective concentrations show similarly improved properties. They are especially characterized in particular by improved response times.