JPH04181922A - Liquid crystal display element and production thereof - Google Patents

Abstract

PURPOSE:To improve orientability and to eliminate the need for rubbing by using crystalline polyimide materials as oriented films on the surfaces of substrates in contact with a liquid crystal. CONSTITUTION:The liquid crystal 3 is sealed between two sheets of the substrates 2 disposed in such a manner that the surfaces having electrodes 1 face each other. The crystalline polyimide materials 4 are formed on the electrodes 1. Any polyimides are usable as the crystalline polyimide materials, insofar as the polyimides are crystalline. The crystalline polyimide used for the oriented films has the uniform high-polymer chains of the polyimide and, the liquid crystal is considered to orient along these high-polymer chains. The oriented films which have the good orientability and do not require rubbing are obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application Liquid crystal display elements requiring an alignment film, ie TN (twisted nematic) and 5TN (super twisted nematic) liquid crystal display elements.

SH (super homeotropic pink) liquid crystal display element and FL
It can be used for C (ferroelectric liquid crystal display element) and the like.

Conventional technology Conventionally, polyimide LBI was used as an alignment film without rubbing.
I is known. For example, it has been reported that a side chain alkyl type polyimide precursor LB film can be used as an alignment film for ferroelectric liquid crystals (15th Liquid Crystal Symposium 3AO
4 (1989) Proceedings, page 276).

Problems to be Solved by the Invention However, the alignment film as described above does not have sufficient alignment stability, and the alignment changes upon heating.

Therefore, in view of the above problems, an object of the present invention is to provide an alignment film that has good alignment properties and does not require rubbing.

Means for Solving the Problem In a liquid crystal display element in which liquid crystal is sandwiched between a pair of substrates with electrodes provided on the surfaces in contact with the liquid crystal, a crystalline polyimide material is used as an alignment film on the surface of the substrate in contact with the liquid crystal. This solved the problems of the present invention.

Function: Since the crystalline polyimide used for the alignment film of the liquid crystal display element of the present invention has aligned polyimide polymer chains, it is thought that the liquid crystal is oriented along the polymer chains.

Example The liquid crystal display element of the present invention will be explained using the drawings.

The drawing is a cross-sectional view of a liquid crystal display element according to one embodiment. A liquid crystal 3 is placed between two substrates 2 whose surfaces having electrodes 1 face each other.
Enclose. A crystalline polyimide material 4 is formed on the electrode 1 . The periphery of the upper and lower substrates 2 is bonded with a sealing material 5 so that the liquid crystal 3 does not leak from between the substrates 2. In addition, in order to maintain a constant distance between the upper and lower substrates 2, spacers 6 are placed between the substrates 2.
placed in between.

The crystalline polyimide material 4 of the present invention is formed on the electrode 1 on the substrate 2. The substrate 1 may be made of any transparent material such as glass, acrylic resin, polycarbonate resin, etc., but it is preferable to use glass from the viewpoint of environmental resistance. Further, if only one of the two opposing substrates 2 is used, a material that reflects light, such as a silicon wafer or aluminum, may be used. Electrode 1 is ITO (
A known transparent electrode such as indium tin oxide (indium tin oxide) or SnO2 can be used. In addition, two opposing boards 2
If only one of the upper electrodes 1 is used, a material that reflects light, such as semiconductor silicon or aluminum, may be used. Furthermore, the electrodes 1 may have a specific pattern for driving the liquid crystal 3, and driving transistors and diodes may be formed on the substrate 2.

As the crystalline polyimide material of the present invention, any polyimide can be used as long as it is crystalline.

Specifically, the crystallinity described in the present invention means that a thin film of a polyimide material has a diffraction peak by X-ray diffraction. Among these crystalline polyimide materials, polyimide containing an alkyl group in its main chain is preferred because of its high crystallinity.In this polyimide having an alkyl group in its main chain, the alkyl groups of adjacent polymer chains are arranged in a backing manner. Furthermore, it is most suitable that the alkyl group contained in the main chain of the crystalline polyimide contains a constitutional unit represented by 2N).

→CH2ST (1) (In the formula, n represents an integer from 5 to I2.) If n is less than 5, the backing of the alkyl chain will be insufficient. Also, n is 1
If the length is longer than 2, the orientation of the backed alkyl chains tends to be inconsistent, resulting in poor liquid crystal alignment stability.

The crystalline polyimide material 4 of the present invention is produced on the surface of the substrate 2 on which the electrode 1 is formed. Crystalline polyimide material is
LB method, dip/pull method.

It may be created by any method such as vacuum evaporation.

The most suitable method is the vacuum coating method of diamine containing an alkyl group and tetracarboxylic dianhydride, or the L of polyamic acid.
B: A film of polyamic acid is formed on a substrate by the peritoneal method and then heated to form a crystalline polyimide material.

The crystalline polyimide material uses diamine and tetracarboxylic dianhydride as raw materials, and then creates polyamic acid.
It is generally produced by heating or chemically ring-closing the polyimide.

Among the diamines that can be used in the present invention, preferred are aliphatic diamines having a structural unit represented by formula (I).

-6CH2-)-7-...(1) (in the formula, n is 5
represents an integer from 12 to 12. ) Examples of the tetracarboxylic dianhydride that can be used in the present invention include pyromellitic acid, 3.3'
, 4.4'-biphenyltetracarboxylic acid, 2.3
．． 3°.

4′-Tetracarboquine biphenyl, 3,3″.

4.4゛-tetracarboquinobiphenyl ether, 2
．． 3.3', 4°-tetracarboxyhensiphenone, 3.3', 4.4'-tetracarboxyhensiphenone, 2,3.3', 4'-tetracarboxyhensiphenone, 2.3, 6.7-Titracarpoquinaphthalene, I, 4.5.7-Titracarpoquinaphthalene, I, 2.5.6-Titracarpoquinaphthalene, 3.
3", 4゜4゜-tetracarboxydiphenylmethane, 2゜2゛-bis(3,4-dicarboxyphenyl)propane, 3.3', 4.4"-tetracarboxydiphenylsulfone, 1,2,7 .8-Tetracarboxyperylene, 2,2-bis+4-(3,4-dicarpoquinphenoxy)phenyl)propane, 3.3", 4,4"
-dimethyldiphenylrantetracarboxylic acid, 3.
Dianhydrides of aromatic tetracarboxylic acids such as 3',4.4''-tetraphenylsilanetetracarboxylic acid, butanetetracarboxylic acid, 1,2.3.4-cyclobutanetetracarboxylic acid, 1,2,3. Examples include dianhydrides of aliphatic or alicyclic tetracarboxylic acids such as 4-cyclopentanetetracarboxylic acid, 2,3,4-furantetracarboxylic acid, and 2,3.4-furantetracarboxylic acid.

Among these tetracarboxylic M, aromatic tetracarboxylic dianhydrides are preferred, and particularly preferred are:
Pyromellitic dianhydride, 3°3°, 4.4'-tetracarpoquinohenzophenone dianhydride, 2,3.3°
, 4-tetracarpoxyhenzophenone dianhydride, 2.
They are 3.3',4'-tetracarpoxybiphenyl ether dianhydride and 3.3',4.4'-biphenyltetracarboxylic dianhydride.

In the vacuum deposition method, a diamine containing an alkyl group and a tetracarboxylic dianhydride are binary deposited. Vacuum level is 104 Torr
R or more is preferable. Diamines and tetracarboxylic dianhydrides are vapor-deposited by heating, but since diamines containing alkyl groups have a higher vapor pressure than tetracarboxylic dianhydrides, it is necessary to control the heating temperature of the vapor deposition source. The temperature can be easily controlled by heating the deposition source with a halogen lamp. The substrate is placed at an angle to the normal from the deposition source. The angle is determined by the pretilt angle of the liquid crystal in the liquid crystal display element to be manufactured.

Since it is not possible to directly accumulate a polyimide film using the LBWi method, it is most preferable to accumulate an amphiphilic polyamic acid salt on a substrate and then heat or chemically close the ring to form a polyimide. The vertical dipping method is optimal for accumulating the LB film on the substrate. At this time, the polyimide molecular chains align due to gravity.

The amphiphilic polyamic acid salt is prepared as follows. A polyamic acid is prepared from a diamine and a tetracarboxylic dianhydride, and a salt of the polyamic acid is obtained by adding N,N-dimethyloctadecylamine to the polyamic acid solution. The reaction solvent is usually an organic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylformamide, N,N-diethylacetamide, dimethylformhoquinde, or N-methyl-2-pyrrolidone. be. The reaction solvent may be used alone or in combination of two or more. Further, in order to obtain a high molecular weight resin, the solvent should be dehydrated before use.

Specific examples will be described below.

(Example 1) ITO electrodes were sputtered onto a Corning 47059 type glass substrate having a thickness of 1.1 m. The ITO forming side of the substrate was directed toward the evaporation source, and the angle between the perpendicular to the evaporation source and the substrate was set to 20 degrees. The substrate was placed into a deposition apparatus. At this time, arrows were drawn on the back side of the substrate from the part closest to the seeding source to the part farthest from it to indicate the direction of the polymer chains.

The distance from the evaporation source to the center of the substrate was set to 200 mm. While the inside of the chamber was kept under vacuum, the substrate was heated to 100 degrees with a heater, and diaminododecane and pyromellitic anhydride were vacuum-deposited. The degree of vacuum during vapor deposition was 5XIO4 Torr. When the film thickness reached 1100 nm, the shutter was closed and the vapor deposition was completed.

Next, the substrate with the deposited film was taken out and heated at 200°C for 2 hours to form a polyimide film. The formation of a polyimide film was confirmed by an infrared absorption spectrum showing that the out-of-plane stretching vibration of the imide ring was at 720 cr'.

Furthermore, when this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 4.2 degrees (planar spacing: 21.OA), indicating that the alkyl chains of the polyimide were backing. It was confirmed.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were set so that the arrow directions (that is, the polymer chain directions) were at 90 degrees. Rixon 9150 manufactured by Chisso Petrochemical Co., Ltd. is placed between these two bonded substrates.
A liquid crystal display element was created by injecting nematic liquid crystal.

When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 2) An ITO electrode was sputtered on a Corning 47059 type glass substrate having a thickness of 1.1 degrees. The fTo forming surface of the substrate was directed toward the evaporation source, and the angle between the perpendicular to the evaporation source and the substrate was set to 20 degrees. Then, the substrate was set in the vapor deposition apparatus. At this time, arrows were drawn on the back surface of the substrate from the part closest to the evaporation source to the part farthest from it to indicate the direction of the polymer chains.

The distance from the vapor deposition source to the center of the substrate was 200 mm. While the inside of the chamber was kept under vacuum, the substrate was heated to 100 degrees with a heater, and diaminodecane and pyromellitic anhydride were vacuum-deposited. The degree of vacuum during vapor deposition was 5×10'Torr. When the film thickness reached 1100 nm, the shutter was closed and the deposition was completed. Next, take out the substrate with the deposited film and
It was heated for 2 hours at 'C to form a polyimide film. It was confirmed from the infrared absorption spectrum that the polyimide film was formed, as the out-of-plane stretching vibration of the imide ring was at 7201°1.

Furthermore, when this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 5.5 degrees (planar spacing: 16.1 A), indicating that the alkyl chains of the polyimide were backing. I confirmed that there is.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were centered so that the direction of the arrow (that is, the polymer chain direction) was at 90 degrees. Rixon 9150 manufactured by Chisso Petrochemical Co., Ltd. is placed between these two bonded substrates.
A liquid crystal display element was created by injecting nematic liquid crystal.

When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 3) A 1-ft ITO pole was sputtered onto a Corning #7059 type glass substrate with a thickness of 1.1 mm.The ITO surface of the substrate was directed toward the evaporation source, and the angle between the perpendicular to the source and the substrate was 2
The temperature was set at 0 degrees and the substrate was set in a vapor deposition apparatus. At this time, arrows were drawn on the back surface of the substrate from the part closest to the evaporation source to the part farthest from it to indicate the direction of the polymer chains.

The distance from the vapor deposition source to the center of the substrate was 200 m. While the inside of the chamber was kept under vacuum, the substrate was heated to 100 degrees with a heater, and diaminobencune and pyromellitic anhydride were vacuum-deposited. The degree of vacuum during vapor deposition was 5×10'Torr. When the film thickness reached 00 nm, the shank was closed and the tea ceremony was completed.

Next, the substrate with the deposited film was taken out and heated at 200'C for 2 hours to form a polyimide film. The formation of a polyimide film was confirmed by an infrared absorption spectrum showing that the out-of-plane stretching vibration of the imide ring was at 720CIII+.

Furthermore, when this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 7.8 degrees (planar spacing: 11.3 A), indicating that the alkyl chains of the polyimide were backing. It was confirmed.

The two substrates having the polyimide films were bonded together using a sealant with the polyimide films facing each other with a gap of 5 microns.At this time, the upper and lower substrates were bonded in the direction of the arrow (i.e., in the direction of the polymer chain). ) made a 90 degree cent. Rixon 9150 ink-free liquid crystal manufactured by Chisso Petrochemical Co., Ltd. was injected between the two bonded substrates to produce a liquid crystal display element. When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 4) A +To electrode was sputtered on a Corning #7059 type glass substrate with a thickness of 1.1 mm. The ITO forming side of the substrate was directed toward the evaporation source, and the angle between the perpendicular to the evaporation source and the substrate was 20 degrees. The substrate was set in the vapor deposition apparatus. At this time, arrows were drawn on the back surface of the substrate from the part closest to the evaporation source to the part farthest from it to indicate the direction of the polymer chains.

The distance from the evaporation source to the center of the substrate was set to 200 mm. While the chamber was being evacuated, the substrate was heated to 100 degrees with a heater, and diaminododecane and 3°3°, 4.4°-tetracarpoxyhenzophenone dianhydride were vacuum-deposited. The degree of vacuum during vapor deposition was 5×10 4 Torr. When the film thickness reached 1100 nm, the shutter was closed and the vapor deposition was completed. Next, take out the substrate with the vapor-deposited film and heat it at 200°C for 2 hours.
It was heated for a period of time to form a polyimide film. It was confirmed from the infrared absorption spectrum that the polyimide film was formed by out-of-plane stretching vibration of the imide ring at 720 cm'l.

Furthermore, when this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 4.2 degrees (planar spacing: 21.OA), indicating that the alkyl chains of the polyimide were backing. After confirming this, the two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other and maintaining a gap of 5 microns.

At this time, the upper and lower substrates were set so that the arrow directions (that is, the polymer chain directions) were at 90 degrees. Rixon 915o manufactured by Chisso Petrochemical Co., Ltd. is placed between these two bonded substrates.
*A liquid crystal display element was created by injecting Machiic liquid crystal.

When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 5) First, diaminododecane was added to a round bottom flask with a capacity of 200 d.
1.0g, 5mmol) and N-methyl-2
- Pyrrolidone (NMP) 400 paper was added and dissolved. Pyromellitic anhydride (1
, 1g, 5mmol I) was added over approximately 15 minutes. The reaction mixture was further stirred at room temperature for 2 hours. Add this solution to 0.2
It was filtered with a μm membrane filter. In this solution, N
, N-dimethyloctadecylamine (4.5g,
15 mmol) to obtain a polyamic acid salt.

This was spread on pure water to create a monomolecular film on the air-water interface. Here, an ITO electrode was sputtered onto a Corning #7059 type glass substrate with a thickness of 1.11III11. After cleaning the surface of the substrate by irradiation with ultraviolet light, the substrate was immersed vertically in a trough to coat the monomolecular film on the substrate. Five layers were accumulated on top.

Thereafter, this substrate was heated at 200°C for 2 hours to imidize it.

When this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 4.2 degrees (planar spacing: 21.OA), indicating that the polyimide alkyl chain was backing. confirmed.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were set so that the direction in which the substrates were pulled up (ie, the direction of the polymer chains) at the time of creating the LB peritoneum was at 90 degrees. Rixon 915 (Inmatic liquid crystal manufactured by Chisso Petrochemical Co., Ltd.) was injected between the two bonded substrates to produce a liquid crystal display element.

When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 6) First, diamino octane (2.2 g + 15 mmol) was placed in a round bottom flask with a capacity of 2,001 d, and N-
100 m of methyl-2-pyrrolidone (NMP) was added and dissolved. While stirring the solution, pyromellitic anhydride (1.1 g, 5 mmol) purified by sublimation was added over about 15 minutes. The reaction mixture was further stirred at room temperature for 2 hours. This solution was filtered through a 0.2 μm membrane filter. In this 7 volume solution, N,N-dimethyloctadecylamine (4,
5 g, 15 mmol) to obtain a polyamic acid salt.

This was spread on pure water to create a monomolecular film on the air-water interface. Here, 47059 manufactured by Corning with a thickness of 1.1 mm
After cleaning the surface of a type glass substrate with an ITO electrode sputtered by irradiation with ultraviolet light, the substrate was immersed vertically in a trough to accumulate five monomolecular films on the substrate.

Thereafter, this substrate was heated at 200''C for 2 hours to imidize it.

When this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 6.4 degrees (planar spacing: 13.8 A), indicating that the polyimide alkyl chain was backing. It was confirmed.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were set so that the arrow directions (that is, the polymer chain directions) were at 90 degrees. Rixon 9150 manufactured by Chisso Petrochemical Co., Ltd. is placed between these two bonded substrates.
A liquid crystal display element was created by injecting nematic liquid crystal.

When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 7) First, diaminopenkune (0.51, g, 5 mmol) was placed in a round bottom flask with a capacity of 200 ml, and 100 IR of N-methyl-2-pyrrolidone (NMP) was added thereto.
was added and melted. While stirring the solution, add about 1.5 g of pyromellitic anhydride (1.1 g, 5 mmol) purified by sublimation.
I added it over a period of time. The reaction mixture was further stirred at room temperature for 2 hours. This solution was filtered through a 0.2 μm membrane filter. N,N-dimethyloctadecylamine (4.5 g, 15 mmol) was added to this solution to obtain a polyamic acid salt.

This was spread on pure water to create a monomolecular film on the air-water interface. Here, #7059 manufactured by Corning Co., Ltd. with a thickness of 1.1 m
After cleaning the surface of a type glass substrate with an ITO electrode sputtered by irradiation with ultraviolet light, the substrate was immersed vertically in a trough to accumulate 5N of a monomolecular film on the substrate.

Thereafter, this substrate was heated at 200°C for 2 hours to imidize it.

When this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 7.8 degrees (planar spacing: 11.3 A), indicating that the alkyl chains of the polyimide were backing. It was confirmed.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were set so that the directions of the arrows (that is, the direction of the polymer chains) were at 90 degrees. Rixon 915 manufactured by Chisso Petrochemical Co., Ltd. is placed between the two bonded substrates.
A liquid crystal display element was prepared by injecting zero nematic liquid crystal. When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Example 8) First, diaminododecane (1.0 g, 5 mmol) was placed in a round bottom flask with a capacity of 200 IRQ, and N-methyl-2-pyrrolidone (NMP) 100a+2 was added thereto and dissolved. While stirring the solution, pyromellitic anhydride (1.1 g, 5 mmol) purified by sublimation was added over about 15 minutes. The reaction mixture was further stirred at room temperature for 2 hours. This solution was filtered through a 0.2 μm membrane filter. In this solution, N,N-dimethyloctadecylamine (4,
5 g, 15 mmol) to obtain a polyamic acid salt.

This was spread on pure water to create a monomolecular film on the air-water interface. Here, #7059 manufactured by Corning Co., Ltd. with a thickness of 1.1 m
ITO on type glass substrate! After cleaning the surface of the substrate onto which the electrode was sputtered by irradiation with ultraviolet light, the substrate was immersed vertically into the trough to accumulate five monolayers on the substrate.

Thereafter, this substrate was heated at 200°C for 2 hours to imidize it.

When this polyimide film was measured by X-ray diffraction (CuKα rays), it had a diffraction peak at 4.2 degrees (planar spacing: 21.OA), indicating that the polyimide alkyl chain was backing. confirmed.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were set so that the direction in which the substrates were pulled up (ie, the direction of the polymer chains) at the time of creating the LB peritoneum was at 90 degrees. A liquid crystal display element was prepared by injecting Rixon 9150 Nemati liquid crystal manufactured by Chisso Petrochemical Co., Ltd. between the two bonded substrates.

When this liquid crystal display element was observed under a polarizing microscope while being driven, good alignment was obtained.

(Comparative example) IT of a substrate in which ITO electrodes were sputtered on a Corning 47059 type glass substrate with a thickness of 1.111111 mm.
The substrate was set in the vapor deposition apparatus with the O-forming surface facing the vapor deposition source and the angle between the perpendicular to the vapor deposition source and the substrate being 20 degrees. At this time, arrows were drawn on the back surface of the substrate from the part closest to the evaporation source to the part farthest from it to indicate the direction of the polymer chains.

The distance from the vapor deposition source to the center of the substrate was 200 m. While creating a vacuum inside the chamber, heat the substrate to 100 degrees G with a heater.
This was heated to vacuum deposit diaminobutane and pyromellitic anhydride. The degree of vacuum during vapor deposition was 5×10'Torr. When the film thickness reached 1100 nm, the shank was closed and the deposition was completed. Next, take out the substrate with the deposited film and
It was heated at °C for 2 hours to form a polyimide film.

When this polyimide film was measured by X-ray diffraction (CuKα rays), no diffraction peak was observed.

The two substrates having the polyimide films were bonded together using a sealing material with the polyimide films facing each other with a gap of 5 microns maintained.

At this time, the upper and lower substrates were set so that the arrow directions (that is, the polymer chain directions) were at 90 degrees. Rixon 9150 manufactured by Chisso Petrochemical Co., Ltd. is placed between these two bonded substrates.
A liquid crystal display element was created by injecting nematic liquid crystal.

However, this liquid crystal display element had non-uniform alignment.

Effects of the Invention By using the manufacturing method of the present invention with the crystalline polyimide of the present invention, it was possible to provide an oriented film with good orientation and no need for rubbing.

[Brief explanation of the drawing]

The figure is a cross-sectional view of one embodiment of a liquid crystal display element using the liquid crystal alignment film of the present invention. ]... Electrode, 2... Substrate, 3...
...Liquid crystal, 4...Liquid crystal alignment film, 5...
Sole material, 6...Spacer. Name of agent: Patent attorney Haruaki Ogata and 2 others +---1? -9 Maku dry 3-E return formula 4--Riseki parrot tsukiri back 5--Se rL class 6--S X-ke

Claims (6)

[Claims] (1) A liquid crystal display element in which a liquid crystal is sandwiched between a pair of substrates with electrodes provided on the surfaces in contact with the liquid crystal, characterized in that a crystalline polyimide material is used as an alignment film on the surface of the substrate in contact with the liquid crystal. Liquid crystal display element. (2) In a liquid crystal display element in which a liquid crystal is sandwiched between a pair of substrates with electrodes provided on the surfaces in contact with the liquid crystal, the alignment film material provided on the surface of the substrate in contact with the liquid crystal contains an alkyl group in the main chain. A liquid crystal display element. (3) The liquid crystal display element according to claim (2), wherein the alkyl group contained in the main chain contains a structural unit represented by formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, n represents an integer from 5 to 12.) (4) A method for producing a liquid crystal display element, which comprises vacuum-depositing a diamine containing an alkyl group and a tetracarboxylic dianhydride on a substrate and then heating the substrate to create an alignment film made of a crystalline polyimide material. . (5) The method for producing a liquid crystal display element according to claim (4), wherein the diamine containing an alkyl group has a structural unit represented by formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, n represents an integer from 5 to 12.) (6) A method for manufacturing a liquid crystal display element, which comprises forming polyamic acid on a substrate by the LB method and then heating it to form an alignment film made of a crystalline polyimide material.