Stock material or miscellaneous articles – Liquid crystal optical display having layer of specified...
Utility Patent
1999-06-21
2001-01-02
Wu, Shean C. (Department: 1756)
Stock material or miscellaneous articles
Liquid crystal optical display having layer of specified...
C252S299630, C558S430000, C560S126000, C560S128000
Utility Patent
active
06168839
ABSTRACT:
TECHNICAL FIELD
The present invention relates to novel liquid crystalline compounds, liquid crystal compositions comprising the compound, and liquid crystal display devices fabricated by using the composition.
BACKGROUND ART
Display devices employing such characteristics as optical (refractive) anisotropy or dielectric anisotropy of liquid crystal substances have widely been utilized for watches, is tabletop calculators, or the likes. While the liquid crystal phase exhibited by the liquid crystal substances includes nematic liquid crystal phase, smectic liquid crystal phase, and cholesteric liquid crystal phase, nematic liquid crystal phase is most general in practical use. Display mode employing the nematic liquid crystal phase includes TN (twisted nematic) type, DS (dynamic scattering) type, guest-host type, and DAP (deformation of aligned phase) type.
As liquid crystalline compounds (including liquid crystal substances and compounds which do not exhibit liquid crystal phase but are effective as component of liquid crystal compositions) used for these display modes, many compounds have heretofore been developed. However, no compounds have been filled in display devices in a state of single component and actually used up to now. The reason is that whereas, as the liquid crystalline compounds expected to be used as liquid crystal materials for display devices, compounds which exhibit a liquid crystal phase at a temperature in a range as wide as possible with room temperature, at which display devices are used at a highest frequency, being its center are desired, the compounds must be sufficiently stable against environmental factors at the time of use and the compounds must have physical properties sufficient to make display devices be driven, liquid it crystalline compounds which satisfy these requirements as single compound have not yet been found.
Accordingly, at present, a plural number of liquid crystalline compounds are mixed to prepare compositions having such characteristics as described above and the compositions are put to practical use as liquid crystal material.
While it is generally considered to be necessary that these liquid crystal compositions are stable against moisture, light, heat, and air which usually exist under conditions wherein the compositions are used, that the compositions are stable against electric field and electromagnetic radiation, and that liquid crystalline compounds to be mixed to prepare the compositions are stable against each other, and are safe, the following characteristics are further desired depending on the purposes of the compositions.
For instance, liquid crystal compositions for liquid crystal display devices of TN mode which are most widely used are considered to be necessary to have a low viscosity, wide temperature range of liquid crystal phase, and large dielectric anisotropy value (&Dgr;&egr;) in addition to the characteristics described above. In order to satisfy the requirement, attempts in which liquid crystal compositions having each different characteristics are mixed have been made. However, when simple substances of liquid crystalline compound having varied characteristics are mixed, liquid crystal compositions to be obtained come to have a large dependency on frequency and temperature, and production of display devices which enable uniform display regardless of the changes in usage conditions becomes impossible.
As components of liquid crystal compositions for nematic display mode, liquid crystalline compounds having a rod-like molecular structure in which six-membered rings are linearly linked are ordinarily used, and characteristics such as temperature range of liquid crystal phase and viscosity of the compounds are known to be approximately determined by the number of the six-membered rings described above.
That is, as the number of six-membered ring decreases, the viscosity generally reduces but the temperature range of liquid crystal phase narrows. On the contrary, as the number of six-membered ring increases, the viscosity increases but the temperature range of liquid crystal phase widens. Particularly in the case where the number of six-membered ring is 4 or more the temperature range of liquid crystal phase remarkably widens. Thus, such case is desirable, but on the other side, the viscosity considerably increases.
Accordingly, liquid crystalline compounds which exhibit a low value as to the viscosity similar to that of the liquid crystalline compounds having a small number of the rings in spite of having such a wide temperature range of liquid crystal phase are desired, and several compounds have been developed heretofore. For instance, cyclohexanecarboxylic acid derivatives expressed by the formula (10) are known as the compound having a comparatively wide temperature range of liquid crystal phase and a low viscosity (Flussige Kristalle in Tabellen, VEB Deutscher Verlagfur Grundstoffindustrie (1974) 34 p and Laid-open Japanese Patent Publication No. Sho 54-151951). However, the derivatives have been found out to have acute toxicity (in this connection, it has been published that the derivatives are extremely high in toxicity such that their half lethal dose (LD
50
) caused by acute toxicity is 18 mg/kg, although it is a result of intravenous injection to mice), and thus it is not preferable from the aspect of environmental safety to fill the derivatives in practical panels and use them.
Further, whereas benzoic acid derivatives expressed by the formula (11) are known as the compounds having a low viscosity (Laid-open Japanese Patent Publication No. Hei 6-57252), the derivatives do not have a wide temperature range of liquid crystal phase such an extent as necessary to withstand practical use.
DISCLOSURE OF THE INVENTION
An object of the present invention is to solve the defects in conventional technology described above. Another object of the present invention is to provide cyclohexane derivatives of novel liquid crystalline compounds having a wide temperature range of liquid crystal phase, being excellent in miscibility with other liquid crystalline compounds, having a low viscosity, being low in toxicity, and being safe; to provide liquid crystal compositions comprising the compound, and to provide liquid crystal display devices fabricated by using the composition.
For achieving the objects described above, the present invention is summarized as follows:
(1) A cyclohexane derivative expressed by the general formula (1)
wherein R represents an alkylene chain having 2 to 10 carbon atoms in which alkylene chain ethylene group (—CH
2
CH
2
—) may be replaced by ethenylene group (—CH═CH—) or methylenoxy group (—OCH
2
—); and M represents COOH or CN group.
(2) The cyclohexane derivative recited in paragraph (1) above wherein M is COOH group.
(3) The cyclohexane derivative recited in paragraph (1) above wherein M is CN group.
(4) The cyclohexane derivative recited in paragraph (1) above wherein R is an alkylene chain having 2 to 10 carbon atoms.
(5) The cyclohexane derivative recited in paragraph (2) above wherein R is an alkylene chain having 2 to 10 carbon atoms.
(6) The cyclohexane derivative recited in paragraph (1) above wherein R is an alkenylene group having 2 to 10 carbon atoms.
(7) A liquid crystal composition comprising at least one cyclohexane derivative recited in any one of paragraphs (1) to (6) above.
(8) A liquid crystal composition comprising, as a first component, at least one cyclohexane derivative recited in any one of paragraphs (1) to (6) above, and comprising, as a second component, at least one compound selected from the group consisting of the compounds expressed by any one of the general formulas (2), (3), and (4)
wherein R
1
, X
1
, L
1
, L
2
, Z
4
, Z
5
may be the same or different among the formulas; R
1
represents an alkyl group having 1 to 10 carbon atoms in which alkyl group one or not adjacent two or more methylene groups may be replaced by oxygen atom or —CH═CH—, and any hydrogen atom may be replaced by fluorine atom; X
1
represents fluorine atom, chlo
Fujita Atsuko
Matsui Shuichi
Miyazawa Kazutoshi
Nakagawa Etsuo
Takeshita Fusayuki
Chisso Corporation
Wenderoth , Lind & Ponack, L.L.P.
Wu Shean C.
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