Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified...
Reexamination Certificate
2001-01-17
2002-12-17
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
C252S299620, C560S183000, C560S187000
Reexamination Certificate
active
06495220
ABSTRACT:
Phenanthrene derivatives for use in liquid-crystalline mixtures have already been disclosed in DE-A 19500768, WO 98/27043, WO 98/27035 or WO 99/24385.
However, since the development of liquid-crystal mixtures can in no way be regarded as complete, display manufacturers are interested in a wide variety of components for mixtures.
In particular, liquid-crystal mixtures are required which have a very broad operating temperature range, but also a very low threshold voltage, for example for use in automobiles, in which a temperature range from −40 to 100° C. can easily occur, but also for portable devices such as mobile telephones and notebook PCs. Moreover, it appears that the tendency toward moving images can be realized with nematic liquid crystals only when the electrode separation of such LCDs is reduced, since the response times are inversely proportional to the square of the electrode separation. This in turn inevitably results in a reduction in brightness and contrast, unless liquid-crystal mixtures having a high optical anisotropy (delta n) value are used. However, materials having a high optical anisotropy usually have high viscosities as well and are thus unfavorable for the objective intended.
There is thus a need for novel, suitable liquid-crystal mixtures and mixture components for these which have a high clearing point and a high optical anisotropy and at the same time have a relatively low rotational viscosity.
It is therefore the object of the present invention to provide novel components for use in nematic or cholesteric liquid-crystal mixtures which have positive dielectric anisotropy values combined with a favorable viscosity/clearing point ratio. Moreover, the compounds should have a high light and UV stability and thermal stability. They should furthermore be suitable for realizing high voltage holding ratios (VHR). They should also be readily obtainable synthetically and thus potentially inexpensive.
It has now been found that these requirements are satisfied in a particular manner by compounds of the formula (I)
R
1
—A—Z
1
(I)
in which:
R
1
is an alkyl radical having 1 to 8 carbon atoms or an alkenyl radical having 2 to 8 carbon atoms, where, in each case, one (nonterminal) —CH
2
— group may also be replaced by —O— or —C(═O)O— and/or one or more H may be replaced by F
A is phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl
Z
1
is F, OCH
x
F
3−x
or CH
x
F
3−x
, where, in each case, x is 0, 1 or 2, OC
2
H
z
F
5−z
or C
2
H
z
F
5−z
, where, in each case, z is 0, 1, 2, 3 or 4, CH═CF
2
or Cl,
with the proviso that 2-fluoro-7-methoxy-phenanthrene is excluded.
Preference is given to those compounds of the formula (I) in which
R
1
is an alkyl radical having 2 to 7 carbon atoms or an alkenyl radical having 2 to 7 carbon atoms, where, in each case, one (nonterminal) —CH
2
— group may also be replaced by —O— and/or one or more H may be replaced by F
A is phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl
Z
1
is F, OCF
3
, CF
3
, OCHF
2
, CHF
2
.
Particular preference is given to those compounds of the formula (I) in which
R
1
is an alkyl radical having 2 to 7 carbon atoms or an alkenyl radical having 2 to 7 carbon atoms or an alkyloxy radical having 2 to 6 carbon atoms or an alkenyloxy radical having 2 to 6 carbon atoms
A is phenanthrene-2,7-diyl or 9,10-dihydrophenanthrene-2,7-diyl
Z
1
is F, OCF
3
, CF
3
.
Very particular preference is given to those compounds of the formula (I) in which
R
1
is a linear alkyl radical having 2 to 7 carbon atoms or a linear alkyloxy radical having 2 to 6 carbon atoms
A is phenanthrene-2,7-diyl
Z
1
is F, OCF
3
, CF
3
.
Very particular preference is likewise given to those compounds of the formula (I) in which
R
1
is a linear alkyl radical having 2 to 7 carbon atoms or a linear alkyloxy radical having 2 to 6 carbon atoms
A is 9,10-dihydrophenanthrene-2,7-diyl
Z
1
is F, OCF
3
, CF
3
.
Special preference is given to
2-ethyl-7-fluoro-phenanthrene
2-fluoro-7-propyl-phenanthrene
2-butyl-7-fluoro-phenanthrene
2-fluoro-7-pentyl-phenanthrene
2-fluoro-7-hexyl-phenanthrene.
Special preference is likewise given to
2-ethyl-7-fluoro-9,10-dihydrophenanthrene
2-fluoro-7-propyl-9,10-dihydrophenanthrene
2-butyl-7-luoro-9,10-dihydrophenanthrene
2-fluoro-7-pentyl-9,10-dihydrophenanthrene
2-fluoro-7-hexyl-9,10-dihydrophenanthrene.
The compounds of the formula (I) are used in liquid-crystal mixtures, preferably in nematic or cholesteric liquid-crystal mixtures. The liquid-crystal mixtures of the invention comprise at least one compound of the formula (I), preferably in an amount of 1 to 40% by weight, based on the liquid-crystal mixture. They preferably comprise at least 3 further components. The invention also provides a liquid-crystal display comprising these liquid-crystal mixtures.
REFERENCES:
patent: 5648021 (1997-07-01), Wingen et al.
patent: 5888422 (1999-03-01), Manero et al.
patent: 6168838 (2001-01-01), Schmidt et al.
patent: 6171519 (2001-01-01), Nonaka et al.
patent: 195 00 768 (1995-09-01), None
patent: WO 98/27035 (1998-06-01), None
patent: WO 98/27043 (1998-06-01), None
patent: WO 99/24385 (1999-05-01), None
Dübal Hans-Rolf
Hornung Barbara
Schmidt Wolfgang
Wingen Rainer
Clariant International Ltd.
Frommer Lawrence & Haug
Wu Shean C.
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