Polymerizable compounds and optical compensators

Details Polymerizable compounds and optical compensators Polymerizable compounds and optical compensators

2003-02-21

2004-12-14

Gulakowski, Randy (Department: 1712)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

C428S001300, C428S413000, C428S523000, C252S299010, C349S117000, C560S076000, C560S083000, C570S129000

Reexamination Certificate

active

06830788

ABSTRACT:

TECHNICAL FIELD
The present invention relates to novel polymerizable compounds which are useful for liquid crystal cells, retardation films and the like. And the present invention also relates to optical compensators comprising polymerized the compounds.
RELATED ART
Liquid crystal compounds should meet some conditions such as having proper melting points and wide temperature ranges of liquid crystal phase for usage of liquid crystal displaying cells, optical compensators and so forth. Various compounds have been synthesized depending on such usage.
Some optical films produced by polymerization of liquid crystal compounds having a polymerizable group are disclosed in JP-A No.07-110469 (the term “JP-a” as used herein means an “unexamined published Japanese patent application), JP-A No. 11-80081, “J. Appl. Phys. Vol. 79(1996), No. 10, 80988105” and so forth. According to them, the optical films can be produced by a method comprising a step of melting a compound having a polymerizabble group on a substrate, a step of orienting the compound, and a step of polymerizing the oriented compound. However, since the compounds disclosed in them have so high melting points, it is often the case that the substrates (such as polymer film) having the compounds thereon would distort because of heat. Thus, it is difficult to produce the films through the orienting and polymerizing process.
The compounds, having a small wavelength dependence of refractive indices, disclosed in them also have strong tendencies to form smectic phases, in which the compounds are hard to be optically uniformly oriented, rather than to form a nematic phase, in which the compounds are easy to be optically uniformly oriented, due to a narrow temperature range of the nematic phase. Thus, it is difficult to produce the films having enough optical uniformity as optical compensator films. Providing polmerizable liquid compounds, which have a low melting point and a wide temperature range of a nematic phase, may benefit the technical field of producing optical compensators, like as the material of substrates are free from limitations.
SUMMARY OF THE INVENTION
The present invention, devised in light of the various above-described problems, has for its object to provide a polymerizable compound having a low melting point and a wide temperature range of nematic liquid phase. Another object of the present invention is to provide an optical compensator having uniform optical property such as uniform retardation.
In one aspect, the invention provides a compound represented by Formula (I):
where A
1
to A
4
are respectively hydrogen or substituents and one of A
1
to A
4
is halogen, alkyl group, alkoxy group, formyl or cyano a substituent; B
1
and B
2
are respectively substituents and at least one of them is a substituent containing acryloyloxy, methacryloyloxy or epoxy.
As preferred embodiment, there are provided the compound wherein both of B
1
and B
2
contain acrylate or methacrylate; the compound wherein at least one of A
1
to A
4
is fluorine, chlorine, or methyl; the compound wherein at least one of A
1
to A
4
is chlorine; the compound wherein both of A
1
and A
3
are hydrogen and both of A
2
and A
4
are substituents; the compound wherein the compound exhibits liquid crystallinity.
In one aspect, the present invention provides an optical compensator comprising a layer formed from a compound represented by Formula (I):
where A
1
to A
4
are respectively hydrogen or substituents and at least one of A
1
to A
4
is halogen, alkyl group, alkoxy group, formyl or cyano; B
1
and B
2
are respectively substituents and at least one of them is a substituent containing acryloyloxy, methacryloyloxy or epoxy.


REFERENCES:
patent: 6338902 (2002-01-01), Hsu et al.
patent: 2003/0072893 (2003-04-01), Nakano et al.
patent: 07-110469 (1995-04-01), None
patent: 08-184858 (1996-07-01), None
patent: 11-080081 (1999-03-01), None
Hikmet et al, “Anisotropic-network-stabilized ferroelectric gels for active matrix addressing”; 1996 American Institute of Physics,J. Appl. Phys. 79 (10), pp. 8098-8105, May 15, 1996.
Lub et al, “The synthesis of liquid-crystalline diacrylates derived from cyclohexane units”,Recl. Trav. Chim. Pays-Bas, 115/06, pp. 321-328, 1996.
Hsu et al, “Preparation of Anisotropic Films for Liquid Crystal Display Application”,Part of the SPIE Conference on Display Technologies II, Taipei, Taiwan, vol. 3421, pp. 46-52, Jul. 1998.
Hsu et al, “Synthesis of Anisotropic Polymer Films for Display Applications”,Polymer Preprints, 38(1), pp. 370-371, 1997.

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