Aromatic diamine derivatives, the preparation thereof and...

Details Aromatic diamine derivatives, the preparation thereof and... Aromatic diamine derivatives, the preparation thereof and...

2003-09-10

2004-09-28

Wu, Shean C. (Department: 1756)

Stock material or miscellaneous articles

Liquid crystal optical display having layer of specified...

Alignment layer of specified composition

C252S299400, C564S307000, C564S347000, C528S170000, C528S179000, C528S185000

Reexamination Certificate

active

06797344

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to new aromatic diamine monomer derivatives and to alignment film materials containing the diamine monomer derivatives for liquid crystal displays (LCDs). The alignment film materials are effective in allowing the liquid crystal molecules positioned between two substrates to have stable, high tilt angles.
(2) Description of the Prior Art
LCD is a liquid crystal photo-electric conversion device, which has advantages of having small size, lightweight, low power consumption, and good display quality, and has become more popular in the field of flat panel display in recent years.
A LCD device typically comprises a display element of twisted nematic (TN) type liquid crystal materials, which responds to electric fields and contain liquid crystal molecules having positive dielectric anisotropy. Normally, the liquid crystal molecules are positioned between a pair of substrates having electrodes, and the alignment directions of the substrates are perpendicular to each other. The alignments of the liquid crystal molecules are controlled by an electric field. For TN type LCDs, it is important to obtain uniform tilt angles between the long axes of the liquid crystal molecules and the inside surfaces of the substrates. The materials utilized to align liquid crystal molecules to have uniform pre-tilt angles are called alignment films.
There are two typical methods for preparing alignment films in industry.
In the first method, an inorganic film is formed from an inorganic material by vapor deposition. For example, a silicon dioxide film can be formed on a substrate by tilt vapor deposition. The liquid crystal molecules are aligned to the direction of the vapor deposition. This method allows the liquid crystal molecules to have a uniform alignment, but is not beneficial to industry.
The second method pertains to coating an organic film on the surface of a substrate and rubbing the coated surface by cotton cloth, nylon, or polyester fabric to align the surface of the organic film such that the liquid crystal molecules can be oriented to the rubbing direction. By this method, it is also easy to obtain uniform alignment. Due to the simplicity of this method, it is more suitable for industry-scale productions. Polymers which can be formed into organic films include, for example, polyvinyl alcohols, polyethylene oxides, polyamides, and polyimides, of which polyimides are the preferred ones due to their good chemical and thermal stabilities.
For different applications, the alignment film materials can be used in TN type, super-twisted nematic (STN) type, or thin film transistor (TFT) type LCDs. In addition to orientation ability and good coating properties, the pre-tile angle is also important for an alignment film. There are many documented methods for controlling the pre-tilt angle. For example, EP 0 604 885 A1 discloses utilizing siloxane copolymer materials as alignment film materials and controlling the pre-tilt angle of the alignment film by adjusting the amount of the siloxane. Nevertheless, the materials are merely suitable for wide viewing STN and TFT LCDs. JP 05313169-A discloses a method of controlling the tilt angle of an alignment film by controlling the degree of ring-closing reaction of a polyamic acid solution to form a polyimide. Nevertheless, the method is merely suitable for high pre-tilt angles. JP 07287235-A discloses a method of using a polyimide having a straight chain alkyl group at an end of the polyimide and a polyamic acid having an aliphatic tetracarboxylic acid structure in an alignment film to increase the pre-tilt angle of the alignment film. Nevertheless, this method is only suitable for STN LCD.
The tilt angle obtained by rubbing a polyimide resin is normally in the range from about 1° to 3° and it is difficult to obtain higher angles. In order to solve this problem, Japanese Laid-Open Patent Application No. 9-278724/1997 discloses a polyimide resin alignment film comprising a cyclohexane side chain containing a carbonaceous straight chain alkyl. Although the pre-tilt angle of the alignment film can be widely controlled, the cost for preparing the diamine monomers is high.
In order to obviate the above-mentioned drawbacks, the inventors of the application have developed new aromatic diamine monomer derivatives, which is useful in an alignment film to provide excellent orientation and stable and high tilt angles.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new aromatic diamine monomer derivative.
It is another object of the present invention to provide a method for preparing the aromatic diamine monomer derivative.
It is still another object of the present invention to provide an alignment film material containing the aromatic diamine monomer derivative for a liquid crystal display (LCD).
DETAILED DESCRIPTION OF THE INVENTION
The aromatic diamine monomer derivative according to the present invention has the structure of formula (I):
wherein,
each of R
1
, R
2
, R
3
, R
5
, and R
6
, independently, is hydrogen or a monovalent organic functional group, and
R
4
is C
4
-C
20
alkyl, CO
2
R
7
, CONR
7
, or (CH
2
)
n
CF
3
, wherein n is an integer of from 1 to 5, and R
7
is C
4
-C
20
alkyl.
In formula (I), preferably, each of R
1
, R
2
, R
3
, R
5
, and R
6
, independently, is hydrogen, C
1
-C
5
alkyl, R
4
is C
4
-C
20
alkyl, and the two amino groups are directly attached to the 2-position and the 4-position of the benzene ring. In a preferred embodiment of the present invention, the compound of formula (I) can be 1-[4-(2,4-diaminophenoxy)phenoxy]octane or 1-[4-(2,4-diaminophenoxy)phenoxy]dodecane.
Typically, the aromatic diamine monomer derivatives of formula (I) of the present invention can be synthesized according to the following scheme:
Therefore, the present invention also provides a method for preparing the aromatic diamine monomer derivatives of formula (I), the method comprising:
(a) reacting a dinitrobenzene compound of formula (II)
 with a hydroquinone compound of formula (III)
 in the presence of a base and an organic solvent to form a compound of formula (IV);
(b) reacting the compound of formula (IV) with a halide R
4
X in the presence of a base and an organic solvent to form a compound of formula (V),
 and
(c) hydrogenating the compound of formula (V) to form the compound of formula (I).
In the compounds of formula (I) to formula (V), R
1
, R
2
, R
3
, R
4
, R
5
, and R
6
are defined as aforementioned, and X is a halogen selected from the group consisting of F, Cl, and Br.
As used hereinbefore, the term “monovalent organic functional group” refers to an organic functional group having single bonding, which includes, but not limited to, substituted or unsubstituted C
1
-C
20
alkyl, preferably C
1
-C
5
alkyl.
As used hereinbefore, the term “alkyl” refers to straight or branched, saturated hydrocarbon chain of from 1 to 20 carbon atoms, which includes, but not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, and the like.
In the above method for preparing the inventive diamine monomer derivatives, the base added to the reactions is used as a catalyst to speed-up the reactions and lower the reaction temperatures. Suitable bases include, but not limited to, the alkaline compounds of IA and IIA metals, preferably the carbonates of IA and IIA metals, and tertiary amines, preferably trimethylamine, triethylamine, diisopropylethylamine, and the like. The organic solvent suitable for the synthesis method includes, but is not limited to, acetone, butanone, N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), and the like. The halides suitable for the synthesis method preferably are C
4
-C
20
alkyl fluoride, chloride, and bromide.
The above-mentioned reduction reaction (hydrogenation) can be performed by any conventionally known hydrogenation method. For instance, the hydrogenation can be performed by hydrogen in the pres

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