Claims
- 1. Liquid-crystalline medium essentially nitrile-free based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR71## in which Hal is fluorine or chlorine and R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms and additionally contains one or more compounds selected from the group comprising the general formulae II, III and IV: ##STR72## in which the individual radicals are as defined below: R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms;
- X is F, Cl, CF.sub.3, OCF.sub.3 or OCHF.sub.2 ;
- y.sup.1 and y.sup.2 are each F; and
- r is 0 or 1;
- characterized in that it contains one or more compounds selected from the group comprising the general formulae IX to XIV: ##STR73## in which R and X are each, independently of one another, as defined above and Y.sup.1 and Y.sup.2 are each, independently of one another H or F.
- 2. Liquid-crystalline medium essentially nitride-free based on a mixture of polar compounds having positive dielectric anisotropy, characterized in that it contains one or more compounds of the general formula I ##STR74## in which Hal is fluorine or chlorine and R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms and additionally contains one or more compounds selected from the group comprising the general formulae II, III and IV: ##STR75## in which the individual radicals are as defined below: R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms;
- X is F, Cl, CF.sub.3, OCF.sub.3 or OCHF.sub.2 ;
- Y.sup.1 and Y.sup.2 are each F, and
- r is 0 or 1.
- 3. Medium according to claim 2, characterized in that it additionally contains one or more compounds selected from the group comprising the general formulae V to VIII: ##STR76## in which R, r, X, Y.sup.1 and Y.sup.2 are each, independently of one another, as defined in claim 2.
- 4. Medium according to claim 2, characterized in that the proportion of compounds of the formulae I to IV together is at least 50% by weight in the total mixture.
- 5. Medium according to claim 2, characterized in that the proportion of compounds of the formula I is from 10 to 50% by weight in the total mixture.
- 6. Medium according to claim 2, characterized in that the proportion of compounds of the formulae II to IV is from 30 to 70% by weight in the total mixture.
- 7. Medium according to claim 2, characterized in that it essentially comprises compounds selected from the group comprising the general formulae I to XIV; ##STR77##
- 8. The method of using a liquid-crystalline medium according to claim 2 for electrooptical purposes which comprises incorporating a liquid crystal medium according to claim 2 in an electrooptical device.
- 9. Electrooptical liquid-crystal display containing a liquid-crystalline medium according to claim 2.
- 10. Medium according to claim 2 which additionally contains a component A comprising one or more compounds of the general formula I' having a dielectric anisotropy of from -1.5 to +1.5 ##STR78## in which R.sup.1 and R.sup.2 are each, independently of one another, n-alkyl, n-alkoxy, .omega.-fluoroalkyl or n-alkenyl having up to 9 carbon atoms, the rings A.sup.1, A.sup.2 and A.sup.3 are each, independently of one another, 1,4-phenylene, 2- or 3-fluoro-1,4-phenylene, trans-1,4-cyclohexylene or 1,4-cyclohexenylene,
- Z.sup.1 and Z.sup.2 are each, independently of one another, --CH.sub.2 CH.sub.2 --, --C.dbd.C--, --CO--O--, --O--CO-- or a single bond,
- and
- m is 0, 1 or 2.
- 11. A liquid-crystalline medium essentially nitrile-free comprising a mixture of polar compounds having positive dielectric anisotropy, which contains one or more compounds of the general formula I ##STR79## in which Hal is fluorine or chlorine and R is alkyl oxaalkyl- fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms and additionally contains one or more compounds selected from the group consisting of general formulae II, III and IV; ##STR80## in which the individual radicals are as defined below: R is alkyl, oxaalkyl, fluoroalkyl or alkenyl, in each case having up to 7 carbon atoms;
- X is F, Cl, CF.sub.3, OCF.sub.3 or OCHF.sub.2 ;
- Y.sup.1 and Y.sup.2 are each F; and
- V is 0 or 1,
- which additionally contains a compound of the formula II6, ##STR81## in which R.sup.1 and R.sup.2 are each, independently of one another, n-alkyl, n-alkoxy, .omega.-fluoroalkyl or n-alkenyl having up to 9 carbon atoms.
- 12. Medium according to claim 11 which additionally contains one or more compounds of the formula I", ##STR82## in which R.sup.0, Q.sup.1, Q.sup.2, Z.sup.1, Z.sup.2, Y, X' and m are as follows:
- R.sup.0 is n-alkyl, n-alkenyl, n-alkoxy or n-oxaalkyl, in each case having up to 9 carbon atoms,
- Q.sup.1 and Q.sup.2 are each, independently of one another, 1,4-phenylene, trans-1,4-cyclohexylene or 3-fluoro-1,4-phenylene-, and one of the radicals Q.sup.1 and Q.sup.2 is alternatively trans-1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl or 1,4-cyclohexenylene, Z.sup.1, Z.sup.2 are each, independently of one another, --CH.sub.2--, --C.dbd.C--, --CO--O--, --O--CO-- or a single bond,
- Y is H or F, a single bond,
- X' is, halogen, CF.sub.3, OCF.sub.3 or OCHF.sub.2, and
- m is 0, 1 or 2.
Priority Claims (1)
Number |
Date |
Country |
Kind |
40 12 025.2 |
Apr 1990 |
DEX |
|
Parent Case Info
This application is a continuation of application Ser. No. 07/721,502, filed Jul. 5, 1991 now abandoned.
US Referenced Citations (5)
Continuations (1)
|
Number |
Date |
Country |
Parent |
721502 |
Jul 1991 |
|