Claims
- 1. A liquid-crystalline medium comprising a mixture of polar compounds having positive dielectric anisotropy, wherein said mixture comprises one or more compounds of formula I: in which:R is straight-chain alkyl or alkoxy having 2 to 7 carbon atoms or alkenyl radical having 2 to 10 carbon atoms, A1 (a) is a trans-1,4-cyclohexylene radical in which, in addition, one or more non-adjacent CH2 groups may be replaced, in each case independently, by —O— or —S—, or a 1,4-cyclohexenylene radical, (b) is a 1,4-phenylene radical, in which, in addition, one or two CH groups may be replaced by N, (c) is a radical from the group consisting of 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydro-naphthalene-2,6-diyl and 1,2,3,4-tetrahydro-naphthalene-2,6-diyl, wherein the radicals (a) and (b) may be monosubstituted or polysubstituted by CN, CH3 or F, Z1 is —CO—O—, —O—CO—, —CH2—O—, —OCH2—, —CH2CH2—, —CF2O—, —OCF2—, —CH═CH—, —C≡C—, —(CH2)4—, —CH═CH—CH2CH2— or a single bond, Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms, or halogenated alkoxy having 1 to 6 carbon atoms, L is H or F, and m is 0 or 1; and wherein said mixture has a clearing point greater than 90° C.
- 2. A medium according to claim 1, wherein said mixture additionally comprises one or more compounds of formulae II to IX: in which the individual radicals have the following meanings:R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms, X0 is F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 carbon atoms, Y1 to Y4 are in each case, independently of one another, H or F, and r is 0 or 1.
- 3. A medium according to claim 2, wherein the proportion of compounds of the formulae I to IX together is at least 50% by weight in the total mixture.
- 4. A medium according to claim 2, wherein the proportion of compounds of the formula I is from 10 to 50% by weight in the total mixture.
- 5. A medium according to claim 2, wherein the proportion of compounds of the formulae II to IX is from 20 to 80% by weight in the total mixture.
- 6. A medium according to claim 1, wherein said mixture comprises a compound of formula I2: whereinR′ is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, it also being possible for one or more CH2 groups in these radicals to be replaced, in each case independently of one another by —O—, , —CO—, —CO—O—, —O—CO—, —S— or —O—CO—O— in such a way that O atoms are not linked directly to one another, and Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms or halogenated alkoxy having 1 to 6 carbon atoms.
- 7. A medium according to claim 6, wherein in formula I2 Y is F, OCHF2 or OCF3.
- 8. A medium according to claim 1, wherein said mixture additionally comprises one or more compounds of the formula: in which: R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms, and L1 is H or F.
- 9. A medium according to claim 1, wherein said mixture additionally comprises one or more compounds of formula XI: in which:R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms, X0 is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms or halogenated alkoxy having 1 to 6 carbon atoms, and Y1 and Y2 are in each case, independently of one another, H or F.
- 10. In an electrooptical display containing a liquid crystal medium, the improvement wherein said medium is a medium according to claim 1.
- 11. In a method of generating an electrooptical effect using a liquid crystal display, the improvement wherein said display is a display according to claim 10.
- 12. A medium according to claim 3, wherein the proportion of compounds of the formulae II to IX is from 20 to 80% by weight in the total mixture.
- 13. A medium according to claim 2, wherein said mixture comprises a compound of formula I2: wherein:R′ is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, it also being possible for one or more CH2 groups in these radicals to be replaced, in each case independently of one another by —O—, , —CO—, —CO—O—, —O—CO—, —S— or —O—CO—O— in such a way that O atoms are not linked directly to one another, and Y is F, Cl, halogenated alkyl having 1 to 6 carbon atoms, halogenated alkenyl having up to 6 carbon atoms or halogenated alkoxy having 1 to 6 carbon atoms.
- 14. A medium according to claim 13, wherein in formula I2 Y is F, OCHF2 or OCF3.
- 15. A medium according to claim 6, wherein said mixture additionally comprises one or more compounds of the formula: in which: R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, each having up to 9 carbon atoms, and L1 is H or F.
- 16. A medium according to claim 6, wherein said mixture additionally comprises one or more compounds of formula XI: in which:R0 is n-alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 9 carbon atoms, X0 is F, Cl, halogenated alkyl, alkenyl or alkoxy having 1 to 6 carbon atoms, and Y1 and Y2 are in each case, independently of one another, H or F.
- 17. In an electrooptical display containing a liquid crystal medium, the improvement wherein said medium is a medium according to claim 6.
- 18. In a method of generating an electrooptical effect using a liquid crystal display, the improvement wherein said display is a display according to claim 17.
Priority Claims (2)
Number |
Date |
Country |
Kind |
198 19 392 |
Apr 1998 |
DE |
|
198 43 582 |
Sep 1998 |
DE |
|
CROSS-REFERENCE TO RELATED APPLICATIONS
This is a divisional application of U.S. application Ser. No. 09/895,199 filed Jul. 2, 2001, which is a continuation of U.S. application Ser. No. 09/302,444, filed Apr. 30, 1999, now abandoned.
US Referenced Citations (18)
Continuations (1)
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Number |
Date |
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Parent |
09/302444 |
Apr 1999 |
US |
Child |
09/895199 |
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US |