JPS59200214A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To easily obtain a liquid crystal display element reduced in weight and thickness by using a specified aromatic polyetherimide for an orientation control film material and making it possible to obtain said film at low temp. in a short time. CONSTITUTION:A material to be used as an orientation control film is an aromatic polyetherimide polymer having repeating units of formula I in which R1- R4 are each H, lower alkyl, lower alkoxy, Cl, or Br; R5, R6 are each H, methyl, ethyl, propyl, CF3, or CCl3; and Ar is p-phenylene, m-phenylene, diphenylene, naphthylene, a group of formula II (X is a divalent group of O, SO2, formula III, S, formula IV, or CH2). The orientation control film is obtained at low temp. in a short time only by evaporating and drying a solvent after coating a substrate with a soln. of this polymer, thus permitting extremely easy and inexpensive fabrication of a liquid crystal display element, as compared with the conventional process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display element using a specific alignment control film.

BACKGROUND ART Conventionally, transparent conductors for liquid crystal display devices have been made of glass whose surface is made transparent and conductive. However, liquid crystal display elements are becoming increasingly lighter and thinner. In response to these demands, glass plates with transparent conductive surfaces cannot be made thinner than a certain level due to the mechanical strength of the glass and manufacturing constraints, so
l+ is said to be the limit. Therefore, there are limits to its applicability to the above-mentioned purposes, and furthermore, there is a problem that the device is damaged during the manufacturing process due to its vulnerability to impact. As a method to satisfy these drawbacks, it is conceivable to use resin instead of conventional glass. However, as described above, in order to make the alignment of the liquid crystal uniform, an additional layer is required to control the alignment.

In the case of conventional glass, the method of obtaining a layer for controlling this orientation is as follows.

A method of obliquely depositing a thin film made of an inorganic compound such as silicon dioxide, and a method of rubbing a thin film made of an organic compound such as polyimide (rubbing in a fixed direction with a cloth or the like) are known. However, all of the above methods require high temperature treatment during film formation. These are no particular problems in conventional glass substrates, but in the case of resin substrates, the substrates cannot withstand the above-mentioned processing temperatures and are deformed, making it impossible to obtain a normal liquid crystal display element.

For example, a resin film provided with a transparent electrode of indium oxide was used, and a polyimide resin was applied to the electrode side.

However, heat treatment at high temperatures for a long time caused thermal deformation of the resin film substrate, making it impossible to obtain a normal liquid crystal element. Therefore.

Temperature lower than the heat deformation temperature of the resin film substrate (100℃
) The polyimide was heat-treated. As a result, the thermosetting reaction of polyimide is insufficient.

During the rubbing process, there was a problem in that scratches or film peeling occurred.

Therefore, after coating the resin film, a thermoplastic resin that does not require a curing reaction, that is, an organic solvent solution of polystyrene, polymethacrylate, polysulfone, polyethersulfone, polycarbonate, etc., is coated on the resin film and dried, and then subjected to a prescribed rubbing process. When attempting to form a liquid crystal element by applying this method, it was not possible to align the liquid crystal display element.

None of these resins could be used as an alignment control film for liquid crystals. As a result of investigating the cause of this, it was found that these resins dissolve in the liquid crystal, and the effect of the rubbed surface disappears.

Therefore, we investigated polyvinyl alcohol and various celluloses as resins insoluble in liquid crystals. That is,
These resins were dissolved in water, the aqueous solution was applied to the resin film, dried, and rubbed, and then the device was assembled. As a result, it was found that the liquid crystal molecules were well aligned to form a liquid crystal alignment control film. However, upon detailed investigation, it was found that the device had poor moisture resistance reliability, and alignment defects occurred due to moisture.

That is, since the resin film has higher moisture permeability than the glass plate, moisture enters the element. However.

Because these alignment control films are water-soluble resins.

It is thought that the ability to orient liquid crystals was lost due to dissolution or swelling caused by water.

In addition, Japanese Patent Application Laid-open No. 55-9518 discloses a liquid crystal display panel using a polymer material (such as nylon) having an amide bond as an alignment treatment film, but this method requires a solution of the alignment control film material. It is necessary to carry out the preparation step 9 at a very high temperature, which is not always satisfactory.

The present invention solves these problems.

That is, 1. The present invention is based on the general formula (■) [However, in formula 2, R, , R2, Ra and lR,
is hydrogen.

Indicates a lower alkyl group, lower alkoxy group, chlorine or bromine, which may be the same or different from each other.
, Rs, 几61-1: hydrogen, methyl group, ethyl group, propyl group, trifluoromethyl group, or trichloromethyl group, which may be the same or different from each other, Ar is p- Phenylene group 9m-Phenylene group, diphenylene group, Sucombination 0, 8 (h,
The present invention relates to a liquid crystal display element containing an aromatic polyetherimide polymer having a repeating unit represented by C-, -8-, -C- or -CH2-C1-, etc.).

The above-mentioned aromatic polyetherimide polymer is insoluble or poorly soluble in liquid crystals and water, and this polymer is dissolved in a specific solvent and applied to a substrate having a transparent conductive film such as indium oxide at a low temperature. After drying by heating at (100 to 120°C), an alignment control film was obtained by rubbing. By arranging the alignment control films of the two substrates thus produced in parallel and facing each other, and sealing liquid crystal between them.

A resin substrate liquid crystal display element having satisfactory characteristics can be completed.

The liquid crystal display element of the present invention generally has good liquid crystal orientation and moisture resistance. Therefore.

Any conventionally known material may be used for the substrate material. For example, a commercially available film or sheet made of epoxy acrylate resin or polyethylene terephthalate having a transparent conductive film can be used. Any film or sheet that has been treated can be used, and there is no particular limitation. Note that in the present invention, of course, a glass substrate may be used.

In the present invention, since it is sufficient to simply evaporate and dry the solvent after coating a substrate with a specific aromatic polyetherimide polymer solution, an alignment control film can be obtained at a low temperature and in a short time. For example, since the formed film is very thin, about 500 to 2000 A, it can be sufficiently dried even below the boiling point.

Therefore, compared to the conventional method of obliquely depositing a thin film made of silicon dioxide or the like on a substrate (mainly a glass plate) or the method of forming a polyimide film, it is possible to obtain a liquid crystal display element that is extremely easy to manufacture and inexpensive. .

Compounds represented by the general formula (U) include para-phenylene diamine, metaphenylene diamine, 4゜4'-diaminodiphenylene, 1,5-diaminonaph py,
4.4'-') aminodiphenyl ether, 4゜4'-
diaminophenyl sulfone, 4.4'-diaminodiphenyl sulfide), 4.4'-diaminodiphenylmethane, 4.4'-diaminopanphenylpropane,
64.4'-diaminodiphenylketone, etc.

Moreover, as a compound represented by the general formula (1111).

Examples include 2.21-bis(4-(2,3-dicarboxyphenoxy)phenyl)-propanedic anhydride, 4.4'-his(2,3-dicarboxyphenoxy)diphenylmethane, and the like.

The compound represented by the general formula (III) is preferably used in an amount of 0.5 to 2 mol, particularly preferably about 1 mol, per 1 mol of the compound represented by the general formula (II).

The above aromatic polyetherimide polymer is.

General light ■) &N-Ar -NH2CI[1 (However, in formula 1, Ar is a compound represented by the general formula (j, which means the same as in the case of Il, and -4<, CIL')
(However, in formula 2, R+, R2, R3, R4, Rs
and R6 have the same meanings as in general formula (I)). The reaction method is melt heating (
(approximately 250 to 300°C).

As a solvent for the alignment control film, dimethyl sulfoxide,
Single or mixed solvents such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and cyclohexanone, and furthermore.

A mixture of the above-mentioned aromatic polyetherimide polymers within a soluble range can be used. For example, even if the above solvents are used alone, a mixed solvent containing appropriate amounts of cellosolves, toluene, xylene, etc. may yield a better film, and aromatic polyetherimide polymers can be dissolved using solvents other than the above. There is no particular limitation as long as it is.

Furthermore, in the present invention, in order to improve film formability, etc.,
Other polymers may also be present.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited to these in any way.

The orientation of the liquid crystal display element was evaluated based on the angle between the long axis direction of the liquid crystal molecules and the surface of the substrate, that is, the inclination (tilt angle θ) between the long axis of the substrate and the liquid crystal molecules. For good orientation, a tilt angle of 1.5 to 3.0 is desirable, and thereby the absolute value of the contrast ratio can be increased. [Tilt angles and their measurement methods can be found in Journal of Appl.
ied Physics) Volume 19 (1980), Boiled 10. It is described on pages 2013-4.

Example 1 It has a repeating unit divided by the formula % formula % and has a heat distortion temperature of 205°C
It is! A 3.5 weight 1N-methylpyrrolidone solution of an aromatic polyetherimide polymer (GE's product name, Ultem) was applied onto a well-washed ethylene terephthalate film having a transparent conductive film using a spinner.
After applying evenly at rpm.

The solvent (N-methylpyrrolidone) was evaporated by drying at 120° C. for 10 minutes to form an orientation control film with a thickness of 850 Å. This film was rubbed in a certain direction with felt to produce a substrate film having an orientation control film.

The alignment control films of the two films produced in this way were placed facing each other, and these films were adhered with a sealing agent such as a polyester adhesive to produce a liquid crystal display element. Note that the sealant was cured at 120° C. for 5 minutes. between the alignment control films of this element.

Phenylcyclohexane liquid crystal (manufactured by Merck & Co.).

ZLI-1132) was placed and the alignment of the liquid crystal was examined between two orthogonal polarizing plates, which showed good alignment. (
Tilt angle: 2.7 degrees) Note that in the device of the present invention, color display is also possible by arranging a guest-host type liquid crystal.

Furthermore, the durability of the liquid crystal display element of the present invention is practical.

There were no particular problems.

As explained above, according to one aspect of the present invention, a transparent conductive substrate pasted with a resin sheet or film is used as a transparent substrate, and a specific alignment control film that can be processed at a temperature below the deformation temperature of this substrate is used. A lightweight and thin liquid crystal display element can be provided.

Furthermore, even in the case of a glass substrate, it is possible to easily obtain a liquid crystal display element that is cheaper than the conventional method.

Claims (1)

[Claims] 1. The alignment control film of the liquid crystal display element has a general formula (11% formula% (
11 [However, in formula 1, + Rt , R2, R3 and R4 are hydrogen. It represents a lower alkyl group, a lower alkyl group, chlorine or bromine, which may be the same or different, and R5 and R6 are hydrogen and a methyl group. Ethyl group, propyl group, trifluoromethyl group. or a trichloromethyl group, which may be the same or different from each other (Ar is a p-phenylene group, a p-phenylene group, a diphenylene group, a naphthylene group, or a trichloromethyl group (where, o CH3 11 is a bond -〇-, -802, C, S, -C- or R
A liquid crystal display element comprising an aromatic polyetherimide polymer having a repeating unit represented by 3 CH2-.