Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified...
Reexamination Certificate
1998-12-01
2001-12-04
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
C252S299010, C252S299610, C252S299630, C252S299640, C252S299650, C252S299660, C252S299670, C544S298000, C544S334000, C544S335000
Reexamination Certificate
active
06326065
ABSTRACT:
TECHNICAL FIELD
The present invention relates to novel liquid crystalline compounds (hereinafter, the term “liquid crystalline compound” is used as a general name for compounds having liquid crystal phase and compounds which do not exhibit liquid crystal phase but are useful as component of liquid crystal compositions). Specifically, the invention relates to liquid crystalline compounds which are preferable for using as component of liquid crystal compositions for TFT type liquid crystal display devices; relates to liquid crystal compositions comprising the liquid crystalline compound; and relates to liquid crystal display devices fabricated by using the liquid crystal composition.
BACKGROUND ART
Liquid crystal display devices employ optical anisotropy and dielectric anisotropy of liquid crystal substances, and display mode of the devices includes TN (twisted nematic) mode, DS (dynamic scattering) mode, G.H (guest.host) mode, DAP (deformation of aligned phases) mode, and STN (super twisted nematic) mode. In order to cope with the request for higher display quality, the demand for display devices of active matrix type a typical example of which is thin film transistor (TFT) has recently been increased.
While properties required of liquid crystal substances are different from the mode to mode, liquid crystal substances are necessary to be stable against moisture, air, heat, and light in any display mode. Besides, the substances should exhibit liquid crystal phase in a temperature range as wide as possible with room temperature being its center, should have a low viscosity, excellent miscibility with other liquid crystalline compounds, large dielectric anisotropy value (&Dgr;&egr;), and most desirable optical anisotropy value (&Dgr;n), and should be chemically and electrically stable. Particularly, a high voltage holding ratio is required of display devices of active matrix type. However, compounds which completely satisfy such requirements as mentioned above by a single compound have not been found up to now, and thus it is an actual situation that liquid crystal compositions obtained by mixing several kind of liquid crystal compounds or liquid crystalline compounds are being used.
Recently, liquid crystal display devices which can be driven at a low voltage and have a high response speed are sought for TFT type liquid crystal devices. Accordingly, development of liquid crystal materials exhibiting a high voltage holding ratio, and having a high &Dgr;n and high &Dgr;&egr; is actively being carried out.
Heretofore, it is known that fluorine substituted liquid crystal materials exhibit a high voltage holding ratio, and that liquid crystalline compounds having a plural number of aromatic rings have a high &Dgr;n. It is also known that compounds in which aromatic ring is pyrimidine ring have a high &Dgr;&egr;. Based on these knowledge, it can be expected that liquid crystalline compounds which have pyrimidine ring and fluorinated phenyl ring have a high &Dgr;n and a high &Dgr;&egr;, and are also high in voltage holding ratio. In Laid-open Japanese Patent Publication No. Hei 2-233626, a liquid crystalline compound (compound expressed by the formula 10) having pyrimidine ring and partially being replaced by fluorine atom is disclosed.
Voltage holding ratio of the compound (formula 10) was 97.5% at 25° C. and 92.9% at 100° C., synthesis and determination of voltage holding ratio of which were carried out by the present inventors according to the description in Laid-open Japanese Patent Publication No. Hei 2-233626. Besides, physical properties of the compound (formula 10) which was calculated by extrapolation from physical properties both of (a) the composition obtained by dissolving the compound (formula 10) in a mother liquid crystal having nematic phase and (b) the mother liquid crystal itself, and their mixing ratio were as follows:
N-I transition point
83.7° C.
&Dgr;&egr;
18.7
&Dgr;n
0.204
Whereas this compound has a comparatively high voltage holding ratio, its &Dgr;&egr; value is insufficient for coping with the request for driving liquid crystal display devices at a low voltage. Besides, the compound (formula 10) has a defect, as shown in Comparative Examples described below, that miscibility with other liquid crystalline compounds at low temperatures is poor. Since the mixing ratio of liquid crystal compounds having a poor miscibility at low temperature in liquid crystal compositions can not be increased, it is impossible to make the characteristics of such compounds contribute to the improvement of characteristics of liquid crystal compositions even if the compounds had some other excellent characteristics.
An object of the present invention is to provide liquid crystalline compounds which have a high voltage holding ratio, high &Dgr;n, and high &Dgr;&egr;, and are excellent in miscibility with other liquid crystalline compounds at low temperatures; to provide liquid crystal compositions comprising the liquid crystalline compound; and to provide liquid crystal display devices fabricated by using the liquid crystal composition.
DISCLOSURE OF THE INVENTION
As a result of diligent investigation by the present inventors, it has been found out that compounds having 1,4-phenylene group at least one hydrogen atom of which is replaced by fluorine atom at a lateral position, and pyrimidine-2,5-diyl group, and being expressed by the general formula (1) have expected properties as liquid crystalline compounds, leading to the achievement of the present invention. That is, the present invention is summarized as follows:
(1) A pyrimidine derivative expressed by the general formula (1)
wherein R represents hydrogen atom or an alkyl group having 1 to 20 carbon atoms, at least one hydrogen atom in the alkyl group may be replaced by a halogen atom, and at least one —CH
2
— in the alkyl group may be replaced by oxygen atom or —CH═CH— but in no case oxygen atoms adjoin to each other;
n1 and n2 are independently 0, 1, or 2 provided that the sum of n1 and n2 is 1 or 2;
ring A and ring B independently represent 1,4-phenylene, fluorine substituted 1,4-phenylene expressed by the formula (a)
or 1,4-cyclohexylene provided that at least one of ring A and ring B is fluorine substituted 1,4-phenylene expressed by the formula (a), and that when ring A and/or ring B is the fluorine substituted 1,4-phenylene, n1 and/or n2 is 1 or 2, at least one not-adjacent —CH
2
— in the 1,4-cyclohexylene may be replaced by oxygen atom, and at least one hydrogen atom in the 1,4-cyclohexylene may be replaced by a halogen atom;
Za, Zb, and Zc independently represent single bond, —CH
2
CH
2
—, —COO—, —CF
2
O—, or —CH
2
CH
2
CH
2
CH
2
—;
Q
1
, Q
2
, Q
3
, Q
4
, Q
5
, Q
6
, and Q
7
independently represent hydrogen atom, a halogen atom, or methyl group provided that when at least one of Za, Zb, and Zc is —CH
2
CH
2
—, Q
2
is fluorine atom;
Y represents hydrogen atom, a halogen atom, or a halogenated alkyl group having 1 to 5 carbon atoms, at least one not-adjacent methylene group in the halogenated alkyl group may be replaced by oxygen atom or sulfur atom; and
each atom constituting this compound may be replaced by its isotope.
(2) The pyrimidine derivative recited in paragraph (1) above wherein n1 is 0, n2 is 1, all of Za, Zb, and Zc are single bond, both of Q
1
and Q
3
are hydrogen atom, and Q
2
is fluorine atom in the general formula (1).
(3) The pyrimidine derivative recited in paragraph (1) above wherein n1 is 0, n2 is 1, all of Za, Zb, and Zc are single bond, and all of Q
1
, Q
2
, and Q
3
are hydrogen atom in the general formula (1).
(4) The pyrimidine derivative recited in paragraph (1) above wherein n1 is 1 and n2 is 0 in the general formula (1).
(5) The pyrimidine derivative recited in paragraph (1) above wherein n1 is 0, n2 is 1, both Za and Zb are single bond, and Zc is —COO— or —CF
2
O— in the general formula (1).
(6) The pyrimidine derivative recited in paragraph (1) above wherein n1 is 0, n2 is 1, both Za and Zc are single bond, and Zb is —COO— or —CF
2
O— in the general formula (1)
(7) The py
Haseba Yasuhiro
Matsui Shuichi
Miyazawa Kazutoshi
Nakagawa Etsuo
Takeshita Fusayuki
Chisso Corporation
Wenderoth , Lind & Ponack, L.L.P.
Wu Shean C.
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