Compositions – Liquid crystal compositions
Patent
1998-03-02
2000-10-24
Wu, Shean C.
Compositions
Liquid crystal compositions
25229964, 25229967, 106401, 560 24, 560 95, 560115, 564188, 526301, 526302, C09K 1920, C09K 1938, C07C 6976, C07C26100, C09D 500, C08F 2602
Patent
active
061362255
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This application is a 371 of PCT/EP96/03756, filed Aug. 26, 1996.
1. Field of the Invention
The present invention relates to novel polymerizable liquid-crystalline compounds of the formula I --Z.sup.2 I polymerization can be effected, --CO--O--, --O--CO--O--, --CO--NR--, --NR--CO--, --O--CO--NR--, --NR--CO--O-- or --NR--CO--NR--, where at least one of the groups Y.sup.3 and Y.sup.4 is --O--CO--O--, --O--CO--NR--, --NR--CO--O-- or --NR--CO--NR--, carbon chain may be interrupted by ether oxygen, thioether sulfur or by nonadjacent imino or C.sub.1 -C.sub.4 -alkylimino groups,
The present invention furthermore relates to liquid-crystal compositions comprising these compounds and possibly one or more chiral compounds, to a process for preparing the novel liquid-crystalline compounds, to a process for coating substrates with the novel compounds or liquid-crystal compositions, and to the use of the compounds or liquid-crystal compositions for producing optical display devices, as cholesteric liquid-crystalline colorants, and to pigments obtainable by polymerizing the liquid-crystal compositions and subsequently comminuting.
2. Description of the Background
Numerous compounds are not converted directly into the liquid, unordered state on warming from the crystalline state with a defined close and long-distance ordering of the molecules, but instead pass through a liquid-crystalline phase, in which, although the molecules are mobile, the molecule axes form an ordered structure. Elongate molecules frequently form nematic liquid-crystalline phases which are characterized by an alignment long-distance ordering owing to parallel arrangement of the long axes of the molecules. If a nematic phase of this type contains chiral compounds, a so-called cholesteric phase forms, which is characterized by a helical superstructure of the long axes of the molecules. The chiral compound here can be the liquid-crystalline compound itself or it can be added to a nematic liquid-crystalline phase as a chiral dope.
Liquid-crystalline materials have remarkable optical properties based on thier anisotropic ordered state. However, the liquid-crystalline ordered state only occurs in a limited temperature range. The temperature range in which liquid-crystalline phases occur is frequently far above the desired use temperature or extends only over a small temperature range.
There are various ways of obtaining and fixing the ordering structures desired for the material properties, even in the solid state. In addition to glass-like solidification on cooling from the liquid-crystalline state, there is also the possibility of copolymerization into polymeric networks or, if the liquid-crystalline compounds contain polymerizable groups, polymerization of the liquid-crystalline compounds themselves.
Polymerizable liquid-crystalline compounds are described, for example, in EP-A 261 712 and in WO 93/05436, WO 95/24453, WO 95/24454 and WO 95/24455. In polymeric form, these compounds usually have the requisite mechanical stabilities, but are in some cases unsatisfactory owing to the temperature level of their liquid-crystalline phases and the temperature range of these phases.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide polymerizable liquid-crystalline compounds or liquid-crystal compositions which have low liquid-crystalline phase temperatures, broad liquid-crystalline phase ranges and, in the polymeric state, good mechanical strength and fixing of the liquid-crystalline ordered state.
We have found that this object is achieved by the polymerizable liquid-crystalline compounds and liquid-crystal compositions comprising the latter described at the outset.
DETAILED DESCRIPTION OF THE INVENTION
For the purposes of the present invention, polymerization is taken to mean all reactions in which polymers are built up, ie. addition polymerization as a chain reaction, addition polymerization as a stepwise reaction and condensation polymerization.
Preferred radicals Z.sup.1 and Z.sup.2 are the foll
REFERENCES:
patent: 5798147 (1998-08-01), Beck et al.
patent: 5833880 (1998-11-01), Siemensmeyer et al.
Etzbach Karl-Heinz
Meyer Frank
Schuhmacher Peter
Siemensmeyer Karl
BASF - Aktiengesellschaft
Wu Shean C.
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