LIQUID-CRYSTALLINE MEDIUM AND HIGH-FREQUENCY COMPONENTS COMPRISING SAME

Abstract

The present invention relates to liquid-crystalline media comprising—one or more compounds of formulae CC and/or CP and—one or more compounds selected from the group of compounds of formulae (I), (II) and (III), 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.

##STR00001##

Claims

1. Liquid-crystal medium, characterised in that it comprises one or more compounds selected from the group of compounds of formulae CC and CP ##STR00185## in which Alkenyl denotes unfluorinated alkenyl having 2 to 15 C atoms, R.sup.01 denotes unfluorinated alkyl having 1 to 17 C atoms or unfluorinated alkenyl having 2 to 15 C atoms, and R.sup.02 denotes unfluorinated alkyl having 1 to 17 C atoms or unfluorinated alkenyl having 2 to 15 C atoms, one or more compounds selected from the group of compounds of formulae I, II and III ##STR00186## 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 ##STR00187## independently of one another, denote ##STR00188## in which L.sup.21 denotes R.sup.21 and, in the case where Z.sup.21 and/or Z.sup.22 denote trans-CH═CH— or trans-CF═CF—, 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-CH═CH— or trans-CF═CF—, 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-CH═CH—, trans-CF═CF— or —C≡C— and the other, independently thereof, denotes trans-CH═CH—, trans-CF═CF— or a single bond, and ##STR00189## independently of one another, denote ##STR00190## 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-CH═CH—, trans-CF═CF—, —C≡C— or a single bond, and ##STR00191## independently of one another, denote ##STR00192## and optionally one or more polymerisable, preferably mesogenic, compounds preferably of formula P
P.sup.a—(Sp.sup.a).sub.s1-(A.sup.1Z.sup.1).sub.n1-A.sup.2-Q-A.sup.3-(Z.sup.4-A.sup.4).sub.n2-(Sp.sup.b).sub.s2-P.sup.b  P 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.2—CH.sub.2—, —CF.sub.2—CF.sub.2—, —CF.sub.2—CH.sub.2—, —CH.sub.2—CF.sub.2—, —CH═CH—, —CF═CF—, —CF═CH—, —(CH.sub.2).sub.3O—, —O(CH.sub.2).sub.3—, —CH═CF—, —C≡C—, —O—, —CH.sub.2—, —(CH.sub.2).sub.3—, CF.sub.2, preferably —CF.sub.2O—, Z.sup.1, Z.sup.4 each, independently of one another, 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.2—CH.sub.2—, —CF.sub.2—CF.sub.2—, —CF.sub.2—CH.sub.2—, —CH.sub.2—CF.sub.2—, —CH═CH—, —CF═CF—, —CF═CH—, —(CH.sub.2).sub.3O—, —O(CH.sub.2).sub.3—, —CH═CF—, —C≡C—, —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, ##STR00193## 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 compounds of formula CC.

3. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more compounds of formula CP as defined in claim 1.

4. 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 μm or more.

5. Liquid-crystal medium according to claim 1, characterised in that it comprises one or more chiral compounds selected from the group of compounds of formulae A-I to A-VI: ##STR00194## including the (R,S), (S,R), (R,R) and (S,S) enantiomers, which are not shown, ##STR00195## 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, ##STR00196## 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—, —S—CO—, —CO—S—, —CH═CH— or —C≡C— 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)m-R, and one of the two is alternatively R.sup.1 or A.sup.3, but both are not simultaneously H, or ##STR00197## 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 ##STR00198## both are a single bond, Z.sup.1 and Z.sup.2 are each, independently of one another, —O—, —S—, —CO—, —COO—, —OCO—, —O—OCO—, —CO—NR.sup.0—, —NR.sup.0—CO—, —O—CH.sub.2—, —CH.sub.2—O—, —S—CH.sub.2—, —CH.sub.2—S—, —CF.sub.2—O—, —O—CF.sub.2—, —CF.sub.2—S—, —S—CF.sub.2—, —CH.sub.2—CH.sub.2—, —CF.sub.2—CH.sub.2—, —CH.sub.2—CF.sub.2—, —CF.sub.2—CF.sub.2—, —CH═N—, —N═CH—, —N═N—, —CH═CH—, —CF═CH—, —CH═CF—, —CF═CF—, —C≡C—, 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—, —O— COO—, —S—CO—, —CO—S—, —CH═CH— or —C≡C—, where no two O and/or S atoms are bonded directly to one another, or a polymerisable group.

6. 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.

7. 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.

8. 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.

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

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

11. 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.

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

13. Component according to claim 12, characterised in that it is suitable for operation in the microwave range.

14. Component according to claim 12, characterised in that it is a phase shifter or a LC based antenna element operable in the microwave region.

15. A method of including a liquid-crystal medium according to claim 1 in a component for high-frequency technology.

16. Process for the preparation of a liquid-crystal medium, characterised in that one or more polymerisable compounds are mixed with one or more compounds selected from the group of the compounds of the formulae CC, CP, I, II and III, as specified in claim 1, and optionally with one or more further compounds and/or with one or more additives.

17. Microwave antenna array, characterised in that it comprises one or more components according to claim 12.

Description

EXAMPLES

[0509] The following examples illustrate the present invention without limiting it in any way.

[0510] 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 and Comparative Examples

Comparative Example 1

[0511] 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 TABLE 1 Composition and properties of the mixture Composition Compound No. Abbreviation 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-5-2 7.0 Σ 100.0 Physical properties T(N, I) = 173° C. n.sub.e(20° C., 589.3 nm) = 1.855 Δn(20° C., 589.3 nm) = 0.335 ε.sub.|| (20° C., 1 kHz) = 8.1 Δε (20° C., 1 kHz) = 4.6 γ.sub.1 (20° C.) = 746 mPa .Math. s V.sub.0 = 2.42 V tan δ.sub.ε r,⊥ (20° C., 19 GHz) = 0.0143 tan δ.sub.ε r,|| (20° C., 19 GHz) = 0.0038 τ (20° C., 19 GHz) = 0.252 η (20° C., 19 GHz) = 17.6

[0512] 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 Example this mixture clearly exhibits inferior properties.

Examples 1.1 to 1.8

[0513] The mixture C-1 is divided in to several parts. To each one of them the compound CC-3-V is added in a specific concentration each. The concentrations used are 60, 50, 40, 30, 25, 20, 10 and 5%, respectively.

TABLE-US-00008 TABLE 2 Compositions of the mixtures Material C-1 CC-3-V Example Mixture Composition Number Concentration/mass-% C-1 100.0 0.0 1.1 40.0 60.0 1.2 50.0 50.0 1.3 60.0 40.0 1.4 70.0 30.0 1.5 75.0 25.0 1.6 80.0 20.0 1.7 90.0 10.0 1.8 95.0 5.0

TABLE-US-00009 TABLE 3a Physical Properties (at 20° C.) of the mixtures investigated Mixture C-1 M-1.1 M-1.2 GT3-23001 MDA-11-4466 MDA-11-4465 Property Value T(N, I)/° C. 173 85.5 97 Δn (20° C., 589.3 nm) 0.335 0.146 0.174 Δε (20° C., 1 kHz) 4.6 1.4 1.8 γ.sub.1 (20° C.)/mPa .Math. s 746 90 123 V.sub.0/V 2.42 3.22 2.99

TABLE-US-00010 TABLE 3b Physical Properties (at 20° C.) of the mixtures investigated Mixture M-1.3 M-1.4 M-1.5 Property Value T(N, I)/° C. 110 124 132 Δn (20° C., 589.3 nm) 0.203 0.236 0.250 Δε (20° C., 1 kHz) 2.2 2.7 3.0 γ.sub.1 (20° C.)/mPa .Math. s 168 231 271 V.sub.0/V 2.82 2.67 2.62

TABLE-US-00011 TABLE 3c Physical Properties (at 20° C.) of the mixtures investigated Mixture M-1.6 M-1.7 M-1.8 Property Value T(N, I)/° C. 139 t.b.d. t.b.d. Δn (20° C., 589.3 nm) 0.266 t.b.d. t.b.d. Δε (20° C., 1 kHz) 3.2 t.b.d. t.b.d. γ.sub.1 (20° C.)/mPa .Math. s 274 t.b.d. t.b.d. V.sub.0/V 2.56 t.b.d. t.b.d. Remarks: t.b.d.: to be determined V.sub.0 in 50 μm test cell, described above.

TABLE-US-00012 TABLE 4a Microwave characteristics and response times (at 20° C.) of the mixtures investigated Mixture C-1 M-1.1 M-1.2 Property Value ε.sub.r,⊥ (20° C., 19 GHz) t.b.d. 2.28 2.31 ε.sub.r,|| (20° C., 19 GHz) t.b.d. 2.65 2.74 tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.0143 0.0087 0.0100 tan δ.sub.ε r,|| (20° C., 19 GHz) 0.0038 0.0030 0.0032 τ (20° C., 19 GHz) 0.252 0.140 0.158 η (20° C., 19 GHz) (FoM) 17.6 16.2 15.8

TABLE-US-00013 TABLE 4b Microwave characteristics and response times (at 20° C.) of the mixtures investigated Mixture M-1.3 M-1.4 M-1.5 Property Value ε.sub.r,⊥ (20° C., 19 GHz) 2.35 2.38 2.38 ε.sub.r,|| (20° C., 19 GHz) 2.85 2.94 2.99 tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.0112 0.0122 0.0127 tan δ.sub.ε r,|| (20° C., 19 GHz) 0.0035 0.0037 0.0038 τ (20° C., 19 GHz) 0.174 0.193 0.203 η (20° C., 19 GHz) (FoM) 15.6 15.9 15.9

TABLE-US-00014 TABLE 4c Microwave characteristics and response times (at 20° C.) of the mixtures investigated Mixture M-1.6 M-1.7 M-1.8 Property Value ε.sub.r,⊥ (20° C., 19 GHz) 2.42 t.b.d. t.b.d. ε.sub.r,|| (20° C., 19 GHz) 3.05 t.b.d. t.b.d. tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.0132 t.b.d. t.b.d. tan δ.sub.ε r,|| (20° C., 19 GHz) 0.0039 t.b.d. t.b.d. τ (20° C., 19 GHz) 0.210 t.b.d. t.b.d. η (20° C., 19 GHz) (FoM) 15.9 t.b.d. t.b.d. Remarks: t.b.d.: to be determined

Comparative Example 2

[0514] The liquid-crystal mixture C-2 Example 16 of DE 10 2010 025 572 A1 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00015 TABLE 5 Composition and properties of the mixture C-2 Composition Compound No. Abbreviation 1 GGP-5-CL 20.0 2 GGP-5-3 12.0 3 PPTUI-3-2 12.0 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 Σ 100.0 Physical properties T(N,I) = 159.5° C. ε.sub.|| (20° C., 1 kHz) = 7.9 Δε (20° C., 1 kHz) = 4.3 γ.sub.1 (20° C.) = 686 mPa .Math. s

[0515] 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 mixtures of the present invention 1 this mixture exhibits, amongst other draw backs, inferior response times.

Example 2

[0516] A liquid-crystal mixture M-2 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00016 TABLE 6 Composition of the mixture investigated (M-2) Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PPTUI-3-4 34.0 3 PGP-2-3 3.0 4 CPGP-5-2 6.0 5 CPGP-5-3 6.0 6 PGP-2-4 3.0 7 PGP-1-2V 3.0 8 PGP-2-2V 3.0 9 PGUQU-3-F 3.0 10  PGUQU-5-F 3.0 11  CC-3-V 12.0 12  CP-3-O1 4.0 Σ 100.0 Physical properties T(N, I) = 153° C. n.sub.e(20° C., 589.3 nm) = 1.799 Δn(20° C., 589.3 nm) = 0.289 ε.sub.|| (20° C., 1 kHz) = 7.9 Δε (20° C., 1 kHz) = 4.3 γ.sub.1 (20° C.) = 347 mPa .Math. s V.sub.0 = t.b.d. V

[0517] This mixture is 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 even in comparison to the Examples 1.1 to 1.8 these mixtures clearly exhibit superior, i.e. significantly smaller, response times. This mixture has an even more improved response behaviour.

[0518] The switching times are determined from the electro-optical response in test cells with antiparallel rubbed orientation layers, having a cell gap of 50 μm, in using an DMS 301 measuring instrument (Autronic Melcher, Germany) at an operating voltage in the range from 20-30 V

[0519] 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.

τ.sub.on≡t(10%)−t(90%)

τ.sub.off≡t(90%)−t(10%)

TABLE-US-00017 TABLE 7 Microwave characteristics and response times (at 20° C.) of the mixture investigated Mixture M-2 M-3 Property Value ε r, ⊥ (20° C., 19 GHz) 2.36 t.b.d. 2.43* ε r, || (20° C., 19 GHz) 3.02 t.b.d. 2.99* tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.0126 0.0160 0.0160* tan δ.sub.ε r,|| (20° C., 19 GHz) 0.0033 t.b.d. 0.0054* τ (20° C., 19 GHz) 0.218 0187 0.230* η (20° C., 19 GHz) 17.4 11.7 14.4* τ.sub.on/ms t.b.d. t.b.d. t.b.d. τ.sub.off/ms t.b.d. t.b.d. t.b.d. τ.sub.sum/ms t.b.d. t.b.d. t.b.d. Remarks: *values at 30 GHz, t.b.d.: to be determined.

[0520] Remarkably, the dielectric loss of the materials is reduced by increased concentration of the chiral dopant.

Example 3

[0521] A liquid-crystal mixture M-3 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00018 TABLE 8 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PZG-5-N 10.0 2 PPTUI-3-2 10.0 3 PPTUI-3-4 15.0 4 PPTUI-4-4 25.0 5 PTP-3-5 10.0 6 PTP-4-5 10.0 7 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 87.5° C. n.sub.e(20° C., 589.3 nm) = 1.746 Δn(20° C., 589.3 nm) = 0.239 ε.sub.|| (20° C., 1 kHz) = 8.4 Δε (20° C., 1 kHz) = 5.2 γ.sub.1 (20° C.) = 156 mPa .Math. s V.sub.0 = 1.67 V

Example 4

[0522] A liquid-crystal mixture M-4 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00019 TABLE 9 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PTP-2-O1 8.0 3 PTP-3-O1 8.0 4 PGP-2-2V 20.0 5 PGUQU-3-F 4.0 6 PGUQU-5-F 5.0 7 PPGUQU-4-F 5.0 7 CC-3-V 30.0 Σ 100.0 Physical properties T(N, I) = 98° C. n.sub.e(20° C., 589.3 nm) = 1.729 Δn(20° C., 589.3 nm) = 0.220 ε.sub.|| (20° C., 1 kHz) = 7.4 Δε (20° C., 1 kHz) = 4.3 γ.sub.1 (20° C.) = 89 mPa .Math. s V.sub.0 = 1.94 V

TABLE-US-00020 TABLE 10 Microwave characteristics (at 20° C.) of the mixtures investigated Mixture M-4 M-5 M-6 Property Value ε r, ⊥ (20° C., 19 GHz) 2.26 2.30 t.b.d. ε r, || (20° C., 19 GHz) 2.69 2.79 t.b.d. tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.0156 0.0175 0.0089 tan δ.sub.ε r,|| (20° C., 19 GHz) 0.0049 0.0054 0.0032 τ (20° C., 19 GHz) 0160 0.176 0.161 η (20° C., 19 GHz) (FoM) 10.2 10.0 18.1 Remarks: t.b.d.: to be determined.

Example 5

[0523] A liquid-crystal mixture M-5 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00021 TABLE 11 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PTP-2-O1 10.0 3 PTP-3-O1 10.0 4 PGP-2-2V 24.0 5 PGUQU-3-F 3.0 6 PGUQU-4-F 3.0 7 PGUQU-5-F 5.0 8 PPGUQU-4-F 5.0 9 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 104.5° C. n.sub.e(20° C., 589.3 nm) = 1.762 Δn(20° C., 589.3 nm) = 0.246 ε.sub.|| (20° C., 1 kHz) = 8.3 Δε (20° C., 1 kHz) = 5.0 γ.sub.1 (20° C.) = 105 mPa .Math. s V.sub.0 = 1.84 V

Example 6

[0524] A liquid-crystal mixture M-6 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00022 TABLE 12 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-4 28.0 2 PTP-4-5 10.0 3 PGP-2-2V 5.0 4 PGP-3-2V 5.0 5 PGUQU-3-F 2.0 6 PGUQU-4-F 2.0 7 PGUQU-5-F 3.0 8 CC-3-V 45.0 Σ 100.0 Physical properties T(N, I) = 84° C. n.sub.e(20° C., 589.3 nm) = 1.673 Δn(20° C., 589.3 nm) = 0.1776 ε.sub.|| (20° C., 1 kHz) = 4.8 Δε (20° C., 1 kHz) = 2.2 γ.sub.1 (20° C.) = 101 mPa .Math. s V.sub.0 = 2.57 V

Example 7

[0525] A liquid-crystal mixture M-7 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00023 TABLE 13 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PPTUI-3-4 30.0 3 PTP-3-5 10.0 4 PTP-4-5 10.0 5 PGUQU-3-F 3.0 6 PGUQU-5-F 7.0 7 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 102° C. n.sub.e(20° C., 589.3 nm) = 1.763 Δn(20° C., 589.3 nm) = 0.237 ε.sub.|| (20° C., 1 kHz) = 6.2 Δε (20° C., 1 kHz) = 3.5 γ.sub.1 (20° C.) = 172 mPa .Math. s V.sub.0 = 2.13 V

TABLE-US-00024 TABLE 14 Microwave characteristics (at 20° C.) of the mixture investigated Mixture M-7 M-8 M-9 Property Value ε r, ⊥ (20° C., 19 GHz) t.b.d. t.b.d. t.b.d. ε r, || (20° C., 19 GHz) t.b.d. t.b.d. t.b.d. tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.0110 t.b.d. 0.0174 tan δ.sub.ε r,|| (20° C., 19 GHz) t.b.d. t.b.d. t.b.d. τ (20° C., 19 GHz) 0.202 t.b.d. 0.200 η (20° C., 19 GHz) (FoM) 19.0 t.b.d. 11.5 Remarks: t.b.d.: to be determined.

Example 8

[0526] A liquid-crystal mixture M-8 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00025 TABLE 15 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PPTUI-3-4 30.0 3 PGP-2-3 10.0 4 PGP-2-2V 10.0 5 PGUQU-3-F 3.0 6 PGUQU-5-F 7.0 7 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 128.5° C. n.sub.e(20° C., 589.3 nm) = 1.780 Δn(20° C., 589.3 nm) = 0.270 ε.sub.|| (20° C., 1 kHz) = 6.7 Δε (20° C., 1 kHz) = 3.7 γ.sub.1 (20° C.) = 220 mPa .Math. s V.sub.0 = 2.27 V

Example 9

[0527] A liquid-crystal mixture M-9 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00026 TABLE 16 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PZG-4-N 10.0 2 PPTUI-3-2 20.0 3 PPTUI-3-4 30.0 4 PGP-2-3 10.0 5 PGP-2-2V 10.0 6 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 116° C. n.sub.e(20° C., 589.3 nm) = 1.772 Δn(20° C., 589.3 nm) = 0.260 ε.sub.|| (20° C., 1 kHz) = 9.4 Δε (20° C., 1 kHz) = 6.0 γ.sub.1 (20° C.) = 197 mPa .Math. s V.sub.0 = 2.13 V

Example 10

[0528] A liquid-crystal mixture M-10 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00027 TABLE 17 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PZG-4-N 10.0 2 PPTUI-3-2 20.0 3 PPTUI-3-4 30.0 4 PTP-3-5 10.0 5 PTP-4-5 10.0 6 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 89.5° C. n.sub.e(20° C., 589.3 nm) = 1.754 Δn(20° C., 589.3 nm) = 0.245 ε.sub.|| (20° C., 1 kHz) = 8.7 Δε (20° C., 1 kHz) = 5.5 γ.sub.1 (20° C.) = 154 mPa .Math. s V.sub.0 = 1.63 V

TABLE-US-00028 TABLE 18 Microwave characteristics (at 20° C.) of the mixture investigated Mixture M-10 M-11 M-12 Property Value ε r, ⊥ (20° C., 19 GHz) t.b.d. t.b.d. t.b.d. ε r, || (20° C., 19 GHz) t.b.d. t.b.d. t.b.d. tan δ.sub.ε r,⊥ (20° C., 19 GHz) 0.01165 t.b.d. t.b.d. tan δ.sub.ε r,|| (20° C., 19 GHz) t.b.d. t.b.d. t.b.d. τ (20° C., 19 GHz) 0.193 t.b.d. t.b.d. η (20° C., 19 GHz) (FoM) 11.6 t.b.d. t.b.d. Remarks: t.b.d.: to be determined.

Example 11

[0529] A liquid-crystal mixture M-11 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00029 TABLE 19 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PPTUI-3-4 35.0 3 GGP-3-CL 5.0 4 GGP-5-CL 20.0 5 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 124° C. n.sub.e(20° C., 589.3 nm) = 1.785 Δn(20° C., 589.3 nm) = 0.275 ε.sub.|| (20° C., 1 kHz) = 6.4 Δε (20° C., 1 kHz) = 3.3 γ.sub.1 (20° C.) = 241 mPa .Math. s V.sub.0 = 2.36 V

Example 12

[0530] A liquid-crystal mixture M-12 having the composition and properties as indicated in the following table is prepared.

TABLE-US-00030 TABLE 20 Composition of the mixture investigated Composition Compound No. Abbreviation 1 PPTUI-3-2 20.0 2 PPTUI-3-4 37.0 3 GGP-3-CL 21.0 4 PGUQU-5-F 2.0 5 CC-3-V 20.0 Σ 100.0 Physical properties T(N, I) = 126° C. n.sub.e(20° C., 589.3 nm) = 1.785 Δn(20° C., 589.3 nm) = 0.276 ε.sub.|| (20° C., 1 kHz) = 6.5 Δε (20° C., 1 kHz) = 3.5 γ.sub.1 (20° C.) = 244 mPa .Math. s V.sub.0 = 2.34 V