JPH09255956A5 - - Google Patents

Description

[0017]
wherein ^R5 is as defined for ^R1 and R1 ^' ;
A ⁷ and A ⁸ are each independently as defined for A ¹ , A ^1′ , A ² and A ^2′ ;
Z ⁷ and Z ⁸ are each independently as defined for Z ¹ , Z ^1′ , Z ² and Z ^2′ , and Q is a polyfluoroalkylene group represented by the formula:
−(O) _q −(CH ₂ ) _r −(CF ₂ ) _s −
(wherein q is 0 or 1,
r is 0 or an integer from 1 to 6, and s is an integer from 0 to 6).
Z is H, F or Cl and p is 0, 1 or 2.

[0018]
In the compounds of formula I and formula II, X and Y are preferably F, _OCF3 , _OCHF2 , CF3 , _OCHFCF3 , _OCF2CHFCF3 , _OC2F5 , _OC3F7 , OCH= _CF2 , _OCF = _CF2 , OCF= _CHF , _in particular _F , _OCF3 or _OCHF2 .
Preferred are IPS displays whose pixels are addressed by an active matrix.
The present invention also relates to a liquid-crystalline medium with positive dielectric anisotropy, which comprises:

[0030]
There is no limit to the total amount of compounds of formulae I to V in the novel mixtures according to the present invention. Thus, these mixtures may contain one or more additional components to optimize various properties. However, the effect observed on address time and threshold voltage is generally greater with increasing total concentration of compounds of formulae I and II.
In a particularly preferred embodiment, the novel media of the present invention contain compounds of formula I and formula II where X= OCF ₂ H and Y=OCF ₃ .

Claims (1)

6. Liquid crystal display according to claim 1, characterized in that the liquid crystal medium contains at least one compound of formula V:
wherein ^R5 is H or an alkyl or alkenyl group having 1 to 15 carbon atoms, which is unsubstituted or has one CN or _CF3 as a substituent, or has at least one halogen as a substituent, and wherein one or more _CH2 groups present in these groups are each independently such that no O atoms are directly bonded to each other;
may be replaced by —O—CO—O—,
^A7 and ^A8 each independently represent
(a) a trans-1,4-cyclohexylene group, in which one CH _group or two or more non-adjacent CH _groups may be replaced by —O— and/or —S—;
(b) a 1,4-phenylene group, in which one or two CH groups may be replaced by N, or (c) a group selected from the group consisting of 1,4-cyclohexenylene, 1,4-bicyclo(2.2.2)octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, and 1,2,3,4-tetrahydronaphthalene-2,6-diyl,
wherein the groups (a) and (b) may each have one or two fluorine atoms as a substituent;
^Z7 and ^Z8 are -CO-O-, -O-CO-, _-CH2O- , -OCH2-, _-CH2CH2- , -CH= _CH- , _-C≡C- or a single bond, or one of the groups ^Z7 and ^Z8 can also be -( _CH2 ) _4- or _-CH =CH- _CH2CH2- ,
Q is a polyfluoroalkylene group represented by the formula:
−(O) _q −(CH ₂ ) _r −(CF ₂ ) _s −
(wherein q is 0 or 1,
r is 0 or an integer from 0 to 6, and s is an integer from 0 to 6;
Z is H, F or Cl and p is 0, 1 or 2.