Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Reexamination Certificate
2000-03-13
2002-04-16
Wu, Shean C. (Department: 1756)
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
C252S299660, C252S299010, C570S127000, C570S129000, C570S144000
Reexamination Certificate
active
06372153
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a liquid crystalline compound and a liquid crystal composition. In more detail, the invention relates to a fluoroalkoxybenzene derivative having an ether linkage and being preferable as a component of liquid crystal composition, a liquid crystal composition comprising the derivative, and a liquid crystal display element fabricated by using the liquid crystal composition.
BACKGROUND ART
Liquid crystal display elements utilize optical anisotropy and dielectric anisotropy of liquid crystalline compounds. They are divided into modes such as twisted nematic (TN), super twisted nematic (STN), dynamic scattering (DS), guest-host (GH) and DAP type mode or so depending on their display modes on the electric optical effects, and also divided into driving modes such as static, time sharing addressing, active matrix and two-frequency addressing scheme.
Recently, particularly high quality display elements are required, and needs for display elements of active matrix types exemplified by a thin film transistor (TFT) type is increased. Furthermore, in order to improve response time against a change of an electric field or in order to lower a driving voltage, there are particularly required liquid crystal materials having higher dielectric anisotropy values (&Dgr;&egr;) and lower viscosity values. Liquid crystal materials used in said liquid crystal, display elements are required to exhibit a liquid crystal phase at temperatures in a wide range and to be stable against heat, light, moisture, air, electric field and electromagnetic radiation or so. However, no compounds are found at present which satisfy such requirements by a single compound, and thus it is a current situation that a plurality, often as much of 20 or more, of liquid crystalline compounds are mixed and used. In particular, since there are recently many cases that liquid crystal display elements are used under such severe conditions as a quite low temperature or so, improvement in miscibility at a low temperature is also required.
Since TFT type liquid crystal display element needs a holding of electric charge stored between electrodes of pixels during a flame period, liquid crystal materials therefor are required to have a particularly high voltage holding ratio. Liquid crystalline compounds having fluorine atoms in their molecules have been used hitherto as liquid crystal materials which satisfy such requirements and have relatively high &Dgr;&egr;.
For example, fluoroalkoxybenzene derivatives shown by the formulae (10) to (18)
wherein R denotes an alkyl group and Rf denotes a fluoroalkyl group, are now known.
However, compounds shown by the general formulae (10) or (11) which are disclosed in WO 94/26838 or DE 19528085 A1 have no or narrow liquid crystal temperature range, and furthermore their electric anisotropy values can never be said high enough.
As to compounds shown by the general formula (12) which are disclosed in Laid-open Japanese Patent Publication No. Hei 7-165656, their dielectric anisotropy values can also never be said high enough. Furthermore, compounds shown by the general formula (14) are disclosed in DE 4027840 A1, but there is no description about their electric characteristics. Furthermore, compounds shown by the general formulae (13), (15), (16) and (18) are disclosed in DE 4218614 A1, EP 640578 A1, DE 4223501 A1, DE 4222371 A1, WO 9213928 A1, DE 4142519 A1 and DE 4027840 A1 or so. But there is no description about their physical properties, so that it can never be said that the invention is disclosed.
In addition, compounds shown by (17) are disclosed without any information about electric characteristics in DE 4301700 A1, but said compounds are considered to have no sufficient &Dgr;&egr; value because dipolar moments thereof are offset by fluoroalkoxy groups at both terminals of the compounds.
We the inventors have studied eagerly to solve the above-mentioned problems and found a novel compound having improved characteristics compared to the known liquid crystalline compounds, and have completed the present invention.
As is clear from the above-mentioned description, an object of the present invention is to provide a liquid crystalline compound of fluoroalkoxybenzene derivatives having ether bond, having in particular large &Dgr;&egr; value, being excellent in miscibility with other liquid crystalline compounds, having a low viscosity and being stable chemically and physically, as well as a liquid crystal composition, and a liquid crystal display element comprising the compound.
DISCLOSURE OF THE INVENTION
Inventions to be claimed in the present application are as follows.
(1) A fluoroalkoxybenzene derivative expressed by the general formula (1)
wherein A
1
, A
2
and A
3
each independently denote trans-1,4-cyclohexylene,1,4-phenylene in which one or more hydrogen atoms may optionally be substituted with a fluorine atom(s), 1,3-dioxane-2,5-diyl, pyrimidine-2,5-diyl or 1-sila-1,4-cyclohexylene; B
1
, B
2
and B
3
each independently denote a single bond, 1,2-ethylene, 1,2-ethenylene, 1,2-ethynylene, oxymethylene, methyleneoxy, carbonyloxy or 1,4-butylene group; R denotes an alkyl group having 1 to 15 carbon atoms optionally substitutable with a halogen atom(s), wherein one or more non-adjacent ethylene groups may be replaced by 1,2-ethenylene group(s); Rf denotes a fluoroalkyl group having 1 to 3 carbon atoms substitutable with two or more fluorine atoms; k, m, and n each independently denote 0 or 1, with the proviso that when k=0 is a case, then one of B
1
, B
2
and B
3
is a methyleneoxy or oxymethylene bond, and that when m+n≧1 is a case, then A
1
or/and A
2
and A
3
are not 1,4-phenylene at the same time, and further when A
1
or/and A
2
and A
3
are trans-1, 4-cyclohexylene or 1,4-phenylene and B
1
or/and B
2
and B
3
are all single bonds, then Rf is never C
2
F
5
, CH
2
CF
3
or CH
2
CF
2
CF
3
, and that when m+n=1 is a case, A
1
or A
2
and A
3
are trans-1, 4-cyclohexylene at the same time, B
1
or B
2
is a single bond and B
3
is 1,2-ethylene, then Rf is never CH
2
CF
2
CF
3
.
(2) A compound recited in paragraph (1) above wherein k=1.
(3) A compound recited in paragraph (1) above wherein one of B
1
, B
2
or B3 is a methyleneoxy or oxymethylene bond.
(4) A compound recited in paragraph (2) above wherein m=0, n=1, A
2
and A
3
are 1, 4-cyclohexylene, and B
2
and B
3
are single bonds.
(5) A compound recited in paragraph (2) above wherein m=0, n=1, A
2
is 1, 4-cyclohexylene, A
3
is 1, 4-cyclohexylene optionally substitutable with a fluorine atom(s), and B
2
and B
3
are both single bonds.
(6) A compound recited in paragraph (2) above wherein m+n=1, A
1
or A
2
and A
3
are both trans-1, 4-cyclohexylenes, B
1
or B
2
is 1, 2-ethylene, and B
3
is a single bond.
(7) A compound recited in paragraph (2) above wherein m+n=1, A
1
or A
2
and A
3
are both trans-1, 4-cyclohexylenes, B
1
or B
2
is a single bond, and B
3
is 1,2-ethylene.
(8) A compound recited in paragraph (2) above wherein m=n=1, and A
1
and A
2
are both trans-1, 4-cyclohexylenes.
(9) A compound recited in paragraph (8) above wherein m=n=1, A
1
and A
2
are both trans-1, 4-cyclohexylenes, A
3
is 1, 4-phenylene one or two hydrogen atoms of which may optionally be substituted with a fluorine atom(s), B
1
and B
3
are single bonds, and B
2
is 1,2-ethylene.
(10) A liquid crystal composition comprising at least one liquid crystalline compound recited in any one of paragraphs (1) to (9).
(11) A liquid crystal composition comprising, as a first component, at least one liquid crystalline compound recited in any one of paragraphs (1) to (9), and as a second component, at least one compound selected from the group of compounds expressed by any one of general formulae (2), (3), and (4)
wherein R
3
denotes an alkyl group having 1 to 10 carbon atoms in which alkyl group any optional non-adjacent ethylene group may be replaced by an oxygen atom or —CH═CH
Hisatsune Yasusuke
Matsui Shuichi
Miyazawa Kazutoshi
Nakagawa Etsuo
Takeshita Fusayuki
Chisso Corporation
Wu Shean C.
LandOfFree
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