Coating processes – Electrical product produced
Patent
1993-02-16
1994-07-12
Lusignan, Michael
Coating processes
Electrical product produced
4274301, 428 1, B05D 512
Patent
active
053287142
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a novel liquid crystal orientation film for orientating a liquid crystal used in liquid crystal devices.
BACKGROUND ART
In watches, TV sets et cetera, flat displays using liquid crystal devices are now widely employed and a liquid crystal orientation film is used in the liquid crystal device. The liquid crystal orientation film has hitherto been formed by, for example, the so-called oblique vapor deposition method in which SiO.sub.2, Au or the like is deposited obliquely, or the so-called rubbing method comprising the step of coating a substrate with a polymer film such as a polyimide type resin and the step of rubbing the polymer film in a given direction by cloth or the like.
Although the liquid crystal orientation film formed by the oblique vapor deposition method is highly advantageous for imparting a given pretilt angle, but because of a vacuum deposition method, it requires a high vacuum of ca. 10.sup.-5 torr and also it is necessary to tilt the substrate, thus the method has a drawback of lacking in mass-producibility.
A liquid crystal orientation film formed by the rubbing method has a drawback of its producibility being affected by dust and static electricity resulting from rubbing and the quality of film being adversely affected.
Hence, a liquid crystal orientation film which can be formed without relying on such conventional methods has been expected.
Recently, a novel type of a liquid crystal orientation film by the use of Langmuir-Blodgett (hereinafter referred to as LB) film which do not require rubbing treatment (Japanese Laid-open Patent Publication No. 209415/1987, Japanese Laid-open Patent Publication No. 23131/1988) are proposed. When the LB film is used as a liquid crystal orientation film, it is difficult to control the pretilt angle of liquid crystal and, depending on the kind of a LB film material used, the liquid crystals are sometimes completely aligned perpendicular or perfectly parallel to the substrate, this resulting in limitation of practicality as a liquid crystal element.
The present invention has been made for solving problems of such conventional arts and is aimed at provision of a liquid crystal orientation film whose liquid crystal pretilt angle is controllable and which is uniform and free from defects.
DISCLOSURE OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal orientation film comprising:
a step of preparing a thin film by laminating a monomolecular film on a substrate having an electrode formed thereon, said monomolecular film being formed by spreading on water surface an amphiphilic high molecular material having a repeating unit as represented by the following general formula (1): ##STR3## wherein R.sup.1 is a tetravalent group containing at least two carbon atoms, R.sup.2 is a divalent group containing at least two carbon atoms and each of R.sup.3 and R.sup.4 is an aliphatic, an alicyclic or an aromatic monovalent group having 1-30 carbon atoms or combinations thereof, which may be substituted by a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group or an acetoxy group, or a hydrogen atom, and at least one of R.sup.3 and R.sup.4 is an aliphatic, an alicyclic or an aromatic monovalent group having 12-30 carbon atoms or combinations thereof, which may be substituted by a halogen atom, a nitro group, an amino group, a cyano group, a methoxy group or an acetoxy group, and
a step of partially imidizing the resulting thin film to a polyimide represented by the following general formula (2): ##STR4## wherein R.sup.1 and R.sup.2 are the same as in the general formula (1), so that the monovalent group having 12-30 carbon atoms contained in the thin film remains at the ratio of 1.5-0.8 pieces per repeating unit as represented by the above general formula (1)
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic view showing an example of the present invention.
OPTIMUM MODE OF THE INVENTION
Explained below is a
Murata Makoto
Nakajima Yasushi
Uekita Masakazu
Casio Computer Co. Ltd. JP
Kanegafuchi Kagaku Kogyo & Kabushiki Kaisha
Lusignan Michael
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