JPH0792570B2 - Liquid crystal display device and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an alignment film used for a liquid crystal display element, and in particular,
The present invention relates to an alignment film formed by a water surface development film forming method suitable for a nematic liquid crystal display device and a ferroelectric liquid crystal display device.

[Conventional technology]

Liquid crystal display devices have been put to practical use in various displays.
In order to obtain good display quality, it is necessary to orient the liquid crystal molecules uniformly. The liquid crystal alignment film plays the role. Therefore, a lot of research and development have been conducted on the alignment film, and until now, an inorganic alignment film in which an inorganic compound such as SiO was obliquely vapor-deposited, an organic polymer film such as polyimide, and an organic alignment film rubbed with a cloth etc. 50-83051, 51-65960
No.) etc. have been put to practical use for liquid crystal display devices. In addition, recently, the alignment film of a liquid crystal display device is formed by a Langmuir-Proget method (hereinafter referred to as the LB method) to form a monomolecular layer of polyimide or the like or a film in which a large number of monomolecular layers are accumulated (Japanese Patent Laid-Open Nos. 62-209415 and 62-209415).
-211617 and 62-215928) are proposed.

[Problems to be Solved by the Invention]

However, each of the above alignment films has serious drawbacks. An inorganic alignment film formed by oblique vapor deposition requires a vacuum device such as a vapor deposition device to form the alignment film, and is not sufficient in terms of mass productivity.

On the other hand, in the case of an organic alignment film, it is extremely excellent in mass productivity, but a polymer film cannot be applied with a uniform film thickness. Further, there are problems such as static electricity being generated by rubbing with a cloth or the like and contamination of the surface of the alignment film. For example, a super twist liquid crystal element (ST
N) [SID International Symposium: p120-123,
(1985)], display unevenness occurs due to non-uniformity of the threshold voltage (Vth) due to the thickness of the alignment film, or non-lighted portions occur due to destruction of the ITO electrode due to static electricity. In addition, shorts between electrodes are likely to occur. Further, contamination of the surface of the alignment film causes non-uniformity of the frequency dependence of the threshold voltage of the device.
This leads to uneven display.

In an active matrix liquid crystal element, a switching element such as a thin film transistor (TFT) or a diode is damaged, or a lighting failure occurs due to a change in switching characteristic. Further, it is difficult to control the load during rubbing on the entire substrate, and there is a problem that scratches are caused by rubbing particularly in a large liquid crystal element.

The alignment film formed by the LB method does not have the above-mentioned problem due to static electricity, but the LB method has a problem in terms of mass productivity. That is, the polymer film formed by the LB method is a monomolecular film with a level of about 4Å, and it is too thin to be ITO.
It is not preferable from the viewpoint of display quality such as visible electrodes. Currently, the organic alignment film currently in practical use is about
A film thickness of 500Å or more is required. However, with the LB method, in order to form such an alignment film, for example, one layer of LB is about 4Å
To make the membrane 500 Å, 125 cumulative operations are required.
As described above, the workability of forming an alignment film by the LB method is extremely poor and is not suitable for actual production.

In view of the above circumstances, an object of the present invention is to provide an alignment film which does not require rubbing treatment and is excellent in mass productivity.

[Means for Solving the Problems]

Briefly describing the present invention, the first invention of the present invention relates to a liquid crystal display element, in which at least one liquid crystal layer and the liquid crystal molecule alignment film are sandwiched between a pair of translucent electrode substrates. In the liquid crystal display element, the thickness of the alignment film is 0.1 μm or less, and at least one of the alignment films is
It is characterized in that it is composed of a water-spreading film of an organic polymer having a thickness of 0.003 μm or more.

A second invention of the present invention is the invention relating to the method for producing a liquid crystal display element of the first invention, wherein in the method for producing a liquid crystal display element, an organic polymer solution is supplied onto the water surface, Is formed in one direction to form a film, and the resulting water surface development film is formed in close contact with a predetermined site on the electrode substrate, and liquid crystal is sealed in a liquid crystal cell created using the electrode substrate. And

The present inventors proceeded with research on an LB film that does not require treatment such as rubbing and has an alignment function for liquid crystal molecules, and arranged the molecular chains of an organic polymer by a water surface development film forming method described in detail later. The present invention was accomplished by succeeding in forming a film on a glass substrate and finding that the film aligns liquid crystal molecules.

That is, the polymer film formed by the water surface development film forming method can form a polymer film having a film thickness of 30Å to 1000Å on a glass substrate in a very short time by a single treatment, and the film developed on the water surface is constant. It was found that a film in which the molecular arrangement of macromolecules is aligned in a certain direction can be prepared by the operation of pulling in the direction. It was also found that the film thus formed has an alignment effect on liquid crystal molecules.

The alignment film formed by the water surface development film formation method does not require rubbing treatment, does not generate static electricity, does not destroy electrodes or TFTs, does not contaminate the alignment film interface, and has a uniform film thickness. Since it can be set, display unevenness does not occur. Furthermore, since a thick polymer having a thickness of 30 liters or more can be formed in a single treatment, it is possible to achieve excellent mass productivity without deteriorating the display quality.

The water surface development film forming method is a method of forming a film using, for example, a device schematically shown in FIG.

That is, FIG. 1 is a schematic view of an example of a water surface development continuous film forming apparatus for manufacturing an alignment film used in the element of the present invention. In FIG. 1, reference numeral 1 is a nozzle, 2 is a water tank, 3 is a water surface, 4 is a film formed, 5 to 7 are rolls, and 8 is a film-shaped substrate.

As shown in FIG. 1, when the metering pump discharges the organic polymer solution from the nozzle 1 onto the water surface 3 in the water tank 2, the solution spontaneously develops on the water surface, and as shown in FIG. A film 4 is produced. That is, FIG. 2 is a development schematic view of an organic polymer solution on the water surface, FIG. 2-1 is a plan view thereof, and FIG. 2-2 is an enlarged side view. In FIG. 2, a means a solution part, b a gel part, and c a solid film part.

The film 4 thus generated is brought into contact with the film-shaped substrate 8 which is moved by the rolls 5 to 7, or the film is attached and transferred to the surface of the film-shaped substrate or a predetermined site on the substrate of the liquid crystal display element and taken out. At this time, the molecular orientation can be imparted by collecting the organic polymer solution at a speed higher than the spontaneous development speed on the water surface. The orientation film thus obtained has the effect of orienting in a fixed direction, and exhibits an infrared dichroic ratio of 1.05 or more due to molecular orientation.

Systems capable of exhibiting the effects of the present invention are all systems capable of forming a film by the water surface development film forming method. As the organic polymer substance, various polyimides and polyamic acids of their precursors, polyparaxylylene, polyester, polycarbonate,
Polyamide, melamine, urea resin, polybutene,
Olefin-based polymers such as polymethyl bentene, cellulose derivatives such as cellulose acetate, fluorine-containing polymers such as polyvinyl fluoride and vinylidene polyfluoride, acrylic polymers such as polymethyl methacrylate and the like can be used. The polyamic acid and polyimide used for forming a particularly suitable alignment film can be obtained by copolymerizing a diamine compound or a dibasic acid hydrazide compound with a tetracarboxylic acid dihydrate.

Examples of the tetracarboxylic acid dianhydride include pyromellitic acid dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride and 3,3', 4,4'-biphenyl tetraanhydride. Carboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, pyridinetetracarboxylic dianhydride, perylenetetracarboxylic dianhydride,
4,4′-disulfonyldiphthalic acid dianhydride, bis [dicarboxyphenoxy) phenyl] propanetetracarboxylic dianhydride, bis [dicarboxyphenoxy) diphenylethertetracarboxylic dianhydride, Examples thereof include bis [dicarboxyphenoxy) phenyl] hexafluoropropanetetracarboxylic acid dianhydride and butanetetracarboxylic acid dianhydride. These can be used alone or in combination of two or more.

Diamine to be copolymerized with the above tetracarboxylic acid dianhydride, as the dibasic acid hydrazide, phenylenediamine, diphenylenediamine, triphenylenediamine,
formula: (Wherein X is a direct _{bond, -O -, - CH 2 -} , - SO 2 -, - CO
-, A compound represented by the following general formula I: A compound having a structure represented by, for example, the formula: A bis (aminophenoxy) diphenyl compound represented by the formula (wherein each X has the same meaning as defined above) is used. Specifically, p-phenylenediamine, m-phenylenediamine, 4,4 ″ -diaminoterphenyl, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 4,4 ′ -Diaminodiphenyl ether, 4,4'-diaminophenyl benzoate, 4,4'-diaminodiphenyl methane, 2,2- (4,4'-diaminodiphenyl) propane, 4,4'-bis (p -Aminophenyloxy) diphenyl sulfone, 4,4'-bis (m-aminophenyloxy) diphenyl sulfone, 4,4'-bis (p-aminophenoxy) diphenyl ether, 4,4'-bis (p-aminophenyloxy) diphenyl ketone, 4,4'-bis (p-aminophenyloxy) diphenylmethane, 2,2- [4,4'-bis (p-aminophenyloxy) diphenyl] propane, 2,2
-[4,4'-bis (p-aminophenoxy) diphenyl] hexafluoropropane, also of the formula: 4,4'-diamino-3-carbamoyldiphenyl ether represented by the following formula and the following diaminosiloxane compound.

Examples of the dibasic acid hydrazide compound include isophthalic acid dihydrazide, terephthalic acid dihydrazide, 4,
4'-dihydrazide diphenyl ether, 4,4'-dihydrazide diphenyl sulfone, 4,4'-dihydrazide diphenyl, 4,4'-dihydrazide diphenyl methane, 4,4 '
-Dihydrazide phenyl benzoate, 4,4'-dihydrazide diphenyl sulfide, 3,3'-dihydrazide diphenyl sulfone, 4,4'-bis (p-hydrazide phenoxy) diphenyl sulfone, 4,4 ' -Bis (m-hydrazidophenoxy) diphenyl sulfone, 4,4'-bis (p-hydrazidophenoxy) diphenyl ether, 2,
2- [4,4'-bis (p-hydrazidophenoxy) diphenyl] propane, 2,2- [4,4'-bis (p-hydrazidophenoxy) diphenyl] hexafluoropropane, oxalic acid dihydrazide, Malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide and the like can be mentioned. These may be used alone or in combination of two or more.

Furthermore, the above-mentioned diamine compound and dibasic acid hydrazide compound can be applied as an N-silylated diamine compound and an N-silylated dibasic acid hydrazide compound by silylation.

The polymerization solvent is not particularly limited as long as it can dissolve polyamic acid and polyimide. For example, N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethylsulfoxide, cresol, phenol, etc. may be used alone or in combination of two or more. Can be used. Further, when one type of solvent does not provide sufficient film development on the water surface, it is also effective to add a second organic solvent as a developing aid. As such a deployment aid,
Mention may be made of aliphatic, cycloaliphatic or aromatic ketones, esters, alcohols, amines, aldehydes, peroxides and mixtures thereof.

The alignment film of the present invention can be directly formed on a substrate provided with an electrode, but may also be provided with a film such as SiO ₂ , Al ₂ O _{3 and} TiO ₂ as an inorganic insulating film in the lower layer or the upper layer of the electrode. Can be used.

Further, in order to obtain a stronger alignment film, one or more kinds of epoxy-based and amino-based silane coupling agents can be used in combination.

The amic acid-based polymer and imide-based polymer used in the present invention may be of any type, but the intrinsic viscosity (concentration 0.5 g / 100 ml, measured at 30 ° C.) is preferably within the range of 0.3 to 5.0. . If the intrinsic viscosity is too low, the strength of the resulting polyimide alignment film will be low. On the other hand, if the intrinsic viscosity is too high, the flow of the polymer solution becomes poor and it becomes difficult to form a thin film.

Further, for the lamination of the alignment film on the substrate, the film on the water surface may be directly laminated, or a method of previously laminating the film on a film such as a separator onto a glass plate with a transparent electrode is used. Is also good. Attaching an alignment film on this substrate is
It may be either a single layer or a multi-layer. In the case of a multi-layer, it is preferable to completely dry the moisture adhering to the attached orientation thin film and then laminate the next layer. The polyamic acid-based alignment film obtained may be imidized by heating or chemical treatment, if necessary.

In addition, the infrared dichroic ratio of the liquid crystal molecular alignment film is shown in FIGS.
As shown, it is affected by the take-off speed. That is, Fig. 3 shows the infrared dichroic ratio of the alignment films prepared by changing the take-up speed, the take-off speed (m / min, horizontal axis) and the infrared dichroic ratio (Abs /
Abs ⊥, vertical axis) graph, Fig. 4 shows FT-IR
3 is a graph showing the infrared dichroism measurement spectrum of the alignment film measured in ^1. with the relationship between wave number (cm ⁻¹ , horizontal axis) and absorbance (vertical axis).

The infrared dichroic ratio of the liquid crystal molecular alignment film is obtained as follows. That is, an alignment thin film is used alone, or an infrared transparent substrate is used, for example, a sample in which an alignment thin film is laminated on a silicon wafer, and a polarizer is provided between this sample and an infrared beam to form an infrared absorption spectrum by a transmission method. To measure. Then, the absorbance (Abs) when the linear polarization axis of infrared rays is parallel to the film forming direction of the thin film and the absorbance (Abs) when it is vertical
⊥) is measured and the Abs / Abs⊥ ratio at a specific wavelength is determined as the infrared dichroic ratio.

The liquid crystals to be used are, for example, the liquid crystals (4) to (10) and the ferroelectric liquid crystals (11) to (15) represented by the following formulas, and the like, and a mixture thereof.

(In the formula, A and B are alkyl groups, alkoxy groups, cyano groups, fluorine, etc.) The liquid crystal layer in the liquid crystal display device of the present invention may contain one or more nematic liquid crystal substances. At that time, the element is
It may have a structure in which the orientation direction between both substrates is twisted by 80 to 280 degrees. In addition, a switching element such as a thin film transistor or a diode may be provided on one substrate.

Further, the liquid crystal layer is made of a ferroelectric liquid crystal substance [(11) to (1
5), etc.] may be contained.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Example 1 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 0.1
Mol and 2,2- [4,4'-bis (p-aminophenoxy) diphenyl] hexafluoropropane (0.1 mol) were stirred in a dimethylacetamide solution at room temperature for 4 hours to synthesize a polyamic acid solution having an intrinsic viscosity of 3.5. The obtained polyamic acid was diluted with dimethylacetamide / acetophenone (equal weight ratio) to 5% to prepare a polyamic acid varnish. This prepared solution was subjected to continuous film formation on the water surface at a film forming speed of 15 m / min, and the film thickness was 1000Å and the infrared dichroic ratio was 1.35. A polyamic acid alignment film of was obtained. The thin film was attached to a striped transparent electrode substrate (electrode width 200 μm, interval 50 μm), and the obtained substrate was coated with a phenylcyclohexane nematic liquid crystal composition through a spacer of 6 μm so that the film forming directions were orthogonal to each other. After injecting and sealing the outer periphery with epoxy resin,
A polarizing plate was attached to the liquid crystal display device so that the polarization axis was in the same direction as the film forming direction of the alignment film. The liquid crystal display device thus obtained shows uniform alignment without any unevenness in alignment. Moreover, as a result of measuring the response speed at a frequency of 32 Hz and an applied voltage of 5 V, the rise (Tr) was 5 ms and the fall (Td) was 20 ms. Furthermore, the voltage transmittance characteristic (γ = V ₉₀ / V ₁₀ ) shown in FIG. 5 of the electro-optical characteristic was 1.50. Note that FIG. 5 is a graph showing the threshold characteristic as a relationship between voltage (V, horizontal axis) and transmittance (%, vertical axis).

Further, the liquid crystal display device of the present invention did not generate static electricity, and neither short between electrodes nor electrode breakage was observed. Further, as a result of visual observation, it was found that there was no mess.

Example 2 The polyamic acid alignment film of the water-spreading film obtained in Example 1 was heat-treated at a temperature of 250 ° C. for 1 hour to be imidized [infrared dichroic ratio
1.30 (wavelength 1500 cm ^-1 )], the film thickness is 600 Å. Then, a liquid crystal display device was obtained in the same manner as in Example 1. The orientation of the obtained liquid crystal display device was good, and the electro-optical characteristics were measured at a frequency of 32 Hz and an applied voltage of 5 V. As a result, Tr was 8 m.
s and Td were 30 ms, and γ was 1.60. Also, the liquid crystal display element of the present invention did not generate static electricity, and neither short between electrodes nor electrode destruction was observed. Furthermore, as a result of visual observation, no messy appearance was observed.

Example 3 0.1 mol of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride and 0.1 mol of 4,4′-bis (m-aminophenoxy) diphenylsulfone were mixed in a mixed solution of cresol and toluene. A polyimide solution having an intrinsic viscosity of 5.0 was synthesized by stirring at 150 ° C. for 5 hours. The obtained polyimide solution was reprecipitated in alcohol, redissolved in 3% with N-methylpyrrolidone, and further mixed with 20% by weight of acetophenone. This preparation solution was subjected to continuous film formation on the water surface at a film forming speed of 10 m / min,
A polyimide alignment film with a film thickness of 300Å and an infrared dichroic ratio of 1.10 (wavelength 1500 cm ^-1 ) was obtained. The thin film was attached to a stripe-shaped transparent electrode substrate (electrode width 200 μm, interval 50 μm), and the substrate was phenylcyclohexane-based and ester-based liquid crystal composition through a spacer of 7 μm so that the film forming directions were orthogonal to each other. After injecting the substance and sealing the outer peripheral portion with an epoxy resin, a polarizing plate was attached in the same direction as the film-forming direction of the alignment film so that a polarization axis was obtained to obtain a liquid crystal display element. The liquid crystal display device thus obtained shows uniform alignment without any unevenness in alignment. Also,
As a result of measuring the response speed at a frequency of 32 Hz and an applied voltage of 5 V, Tr
Was 13 ms, Td was 35 ms, and γ was 1.65. Also, the liquid crystal display element of the present invention did not generate static electricity, and neither short between electrodes nor electrode destruction was observed. Furthermore, as a result of visual observation, no messy appearance was observed.

Example 4 0.05 mol of pyromellitic dianhydride, 0.05 mol of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride and 0.1 mol of isophthalic acid dihydrazide were stirred in a dimethylacetamide solution at room temperature for 6 hours. A polyhydrazide acid solution with an intrinsic viscosity of 2.4 was synthesized. The obtained polyhydrazide acid was diluted to 2%, and the following conditions were the same as in Example 3,
A polyhydrazide acid alignment film with a film thickness of 200Å and an infrared dichroic ratio of 1.20 (wavelength 1500 cm ^-1 ) was obtained. A phenylcyclohexane ester-based liquid crystal composition was injected into the obtained substrate through a 5 μm spacer so that the film forming directions were orthogonal to each other, and after sealing with an epoxy resin, a polarizing plate was attached to obtain a liquid crystal display element. . The liquid crystal display device thus obtained shows uniform alignment without any unevenness in alignment. Also, the frequency 32Hz,
As a result of measuring the response speed with an applied voltage of 5 V, Tr is 10 ms and Td is
It was 30 ms and γ was 1.48. Also, the liquid crystal display element of the present invention did not generate static electricity, and neither short between electrodes nor electrode destruction was observed. Furthermore, as a result of visual observation,
There is no appearance of Nesa.

Example 5 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 0.0
5 mol, 0.05 mol of pyromellitic dianhydride, 0.05 mol of 4,4'-diaminodiphenyl ether, 0.05 mol of 2,2- [4,4'-bis (p-hydrazidophenoxy) diphenyl] hexafluoropropane Was stirred in an N-methylpyrrolidone solution at room temperature for 8 hours to synthesize a polyamic acid-hydrazide acid solution having an intrinsic viscosity of 1.5. The obtained polyamic acid-hydrazide acid solution was diluted to 1% and adjusted to be N-methylpyrrolidone / acetophenone (equal weight ratio). The prepared solution was subjected to continuous film formation on the water surface at a film-forming speed of 10 m / min. The film thickness was about 30Å, the infrared dichroic ratio was 1.15 (wavelength 1500 cm.
^-1 ) Polyamic acid-hydrazide acid alignment film was obtained. The thin film was attached on a stripe-shaped transparent electrode substrate (electrode width 200 μm, interval 50 μm), and the obtained substrate was strengthened to exhibit the Sc ^* phase shown below through a spacer of 4 μm so that the film forming directions were orthogonal to each other. Dielectric liquid crystal composition Was injected and the outer peripheral portion was sealed with an epoxy resin, and then a polarizing plate was attached so that the polarization axis was in the same direction as the film forming direction of the alignment film to obtain a liquid crystal display element. The liquid crystal display device thus obtained shows uniform alignment without any unevenness in alignment. The electro-optical characteristics were also measured. Figure 6 shows this memory evaluation characteristic
It is a graph showing the relationship between time and brightness and applied voltage,
As shown in Fig. 6, the contrast ratio C _R = B ₄ when an electric field is applied.
/ B _1, when the contrast ratio _{^{C R M = B 3 / B}} 2 between memory 2 states, their ratio is M = a ^{_{(C R M -1) / (}} C R -1). That is, as a parameter showing the stability of the memory state, the result of measuring the memory characteristic M of the contrast ratio between the two states of the memory and the contrast ratio when an electric field is applied is M =
1, the contrast ratio was 15: 1, which was a good value.
Further, the liquid crystal display device of the present invention did not generate static electricity, and neither short between electrodes nor electrode breakage was observed.

Example 6 0.1 mol of 3,3 ', 4,4'-binzophenone tetracarboxylic acid dianhydride and 0.09 mol of 4,4'-bis (m-aminophenoxy) diphenyl sulfone, 4,4'-diaminodiphenyl Stirring 0.01 mol of ether-3-carbonamide in a dimethylacetamide solution at room temperature for 3 hours gives an intrinsic viscosity of 0.
A polyamic acid solution of 8 was synthesized. The obtained polyamic acid solution was diluted to 2%, and otherwise the same as in Example 5, and the film thickness was about 100Å and the infrared dichroic ratio was 1.40 (wavelength 1500 cm ^-1 ).
An alignment film obtained by the water-spreading method of polyamic acid in water was obtained. Then, it was heated at 200 ° C. for 1 hour to form a polyimide film.

Then, 3% by weight of a dichroic dye (LSB235 manufactured by Mitsubishi Kasei Co.) was mixed in the ferroelectric liquid crystal used in Example 5, and the orientation, memory and contrast ratio were evaluated. As a result, there was no unevenness in alignment, uniform alignment was exhibited, and the memory property (M) showed a good value of M = 1 and the contrast ratio was 1 as well.
It showed 2: 1. Further, the liquid crystal display device of the present invention did not generate static electricity, and neither short between electrodes nor electrode breakage was observed.

Example 7 0.1 mol of pyromellitic dianhydride, 0.08 mol of a silyl compound of 2,2- [4,4'-bis (p-aminophenoxy) diphenyl] propane, and 0.02 mol of sebacic acid dihydrazide were dissolved in a N-methylpyrrolidone solution. After stirring for 5 hours at room temperature, a polyamic acid-hydrazide acid solution having an intrinsic viscosity of 3.5 was synthesized. The obtained polyamic acid-hydrazide acid solution was added to 6
% And add acetophenone to N-methylpyrrolidone
On the amorphous silicon semiconductor substrate (the number of pixels: 20 × 20) mixed with 30 weights, an approximately 1000Å orientation film of the water surface development film forming method was formed under the same conditions as in Example 5, and after heating at 180 ° C. for 2 hours, Nematic liquid crystal composition shown below Was injected and the outer peripheral portion was sealed, and then a polarizing plate was attached in the same direction as the film-forming direction of the alignment film to obtain an active matrix liquid crystal display device. The liquid crystal display device thus obtained shows uniform alignment with no unevenness of alignment, and
As a result of performing the T operation, it was confirmed that all pixels were normally lighted. Therefore, the liquid crystal display device did not generate static electricity, and no TFT damage was observed.

Example 8 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 0.1
Mol and 2,2- [4,4'-bis (p-aminophenoxy) diphenyl] hexafluoropropane (0.09 mol) and diaminosiloxane (0.01 mol) in a dimethylacetamide solution.
A polyamic acid siloxane solution having an intrinsic viscosity of 3.2 was synthesized by stirring at room temperature for 10 hours. The obtained polyamic acid siloxane solution was diluted to 4% to prepare dimethylacetamide / acetophenone (equal weight ratio). This prepared solution was applied to a striped transparent electrode substrate (electrode width 200 μm,
Water-spreading continuous film formation was performed under the same conditions as in Example 5 at an interval of 50 μm, and the film thickness was about 400Å and the infrared dichroic ratio was 1.45 (wavelength 1500 cm).
^-1 ) Polyamic acid siloxane acid alignment film was obtained. Then, after heating at 250 ° C. for 1 hour to close the ring to the polyimide siloxane, the substrate and the absorption axis after polarization are adjusted so that the twist angle of the liquid crystal molecule is 220 degrees, and the nematic liquid crystal composition shown below is provided through a 6 μm spacer. Was injected and sealed. After that, as a result of examining the scanning domain (domain that scatters light) of the STN liquid crystal element, it was confirmed that no domain was generated and a stable lighting state was obtained in all pixel regions. In addition, the STN liquid crystal display element also did not generate static electricity, and neither a short between electrodes nor electrode destruction was observed. Furthermore, as a result of visual observation,
There is no appearance of Nesa.

Comparative Example 1 0.1 mol of pyromellitic dianhydride and 0.1 mol of 4,4'-diaminodiphenyl ether were stirred in a dimethylacetamide solution at room temperature for 5 hours to synthesize a polyamic acid solution. The obtained polyamic acid solution was diluted to 3% and spin-coated (3000 rpm, 60 seconds) to form an alignment film of about 500 Å on a stripe-shaped transparent electrode substrate (electrode width 200 μm, interval 50 μm). After that, the rotor wrapped with AB label cloth was heated and closed at 250 ° C for 1 hour (rotation speed 600 rpm, loading amount 0.4 m).
m) was rubbed to adjust the absorption axes of the substrate and the polarizing plate so that the twist angle of the liquid crystal molecules would be 220 degrees, the nematic liquid crystal used in Example 8 was injected, and the liquid crystal was sealed with an epoxy resin and evaluated. As a result, the generation of static electricity was observed, and a short between the electrodes and electrode destruction occurred, causing a lighting failure. In addition, the threshold (V _th ) characteristics are changed and lowered in each part of the liquid crystal element, and the stability of the entire element is poor.

Comparative Example 2 0.1 mol of 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride and 0.1 mol of 2,2- [4,4'-bis (p-aminophenoxy) diphenyl] propane were added to N-methyl. In a pyrrolidone solution, a stirred polyamic acid solution was synthesized at room temperature for 8 hours. The obtained polyamic acid solution was diluted to 7%, and the solution was placed on an amorphous silicon semiconductor substrate (pixel number 20 x 2
An alignment film having a thickness of about 1000Å was formed by using a printing machine at 0).
After that, the rotor was wrapped with AB label cloth heated at 200 ° C. for 2 hours and rotated (rotation speed 600 rpm, depth of cut 0.25 mm) for rubbing to inject nematic liquid crystal used in Example 7, and seal with epoxy resin. The electro-optical characteristics were evaluated.
As a result, when a TFT operation was performed on this liquid crystal display element, static electricity was found to occur, and lighting failure occurred at several pixels.
The display could not be stable.

〔The invention's effect〕

As described above, the liquid crystal molecular alignment film used in the present invention is particularly preferably an amic acid polymer and an imide polymer, and is formed with a film thickness of 30 to 1000Å in a very short time by one treatment, Since the infrared dichroic ratio due to the orientation is 1.05 or more, the molecules are well oriented as they are without a rubbing treatment step. Therefore, it can be directly used for various liquid crystal alignment elements. Further, as an effect, static electricity is not generated, no electrode breakage or transistor damage is observed, and the alignment film can be efficiently manufactured continuously, which is suitable for mass production.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a water surface continuous film forming apparatus for producing an alignment film used in the device of the present invention, and FIG. 2 is a schematic view showing a state in which an organic polymer solution is spread on the water surface. By the way, FIG. 2-1 is a plan view thereof, FIG. 2-2 is an enlarged side view, and FIG. 3 is a graph showing infrared dichroic ratios of alignment films produced by changing the take-up speed, and FIG. FIG. 5 is a graph showing the infrared dichroism measurement spectrum of the alignment film measured by FT-IR, FIG. 5 is a graph showing threshold characteristics, and FIG. 6 is a graph showing memory property evaluation characteristics. 1: Nozzle, 2: Water tank, 3: Water surface, 4: Formed film, 5-7: Roll, 8: Film-shaped substrate

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Teruo Kitamura 4026 Kuji Town, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Akio Mukai 4026 Kuji Town, Hitachi City, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. (72) Inventor Yasuhiko Kando 3300 Hayano, Mobara-shi, Chiba Hitachi Ltd. Mobara factory (72) Inventor, Saji Ii, 1-2, Shimohozumi, Ibaraki-shi, Osaka Nitto Denki Kogyo Co., Ltd. Company Central Research Institute (72) Inventor Yasuo Fujimura 1-2-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Electric Industry Co., Ltd. Central Research Laboratory (72) Noboru Masutani 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Electric Industry Co., Ltd. Central Research Laboratory (72) Inventor Tsunetaka Matsumoto 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Electric Works Co., Ltd. center within the Institute (56) Reference Patent Sho 62-98325 (JP, A) JP Akira 62-180777 (JP, A) Tokuoyake Akira 58-35722 (JP, B1)

Claims (11)

[Claims] 1. A liquid crystal display element comprising a pair of electrode substrates, at least one of which is translucent, sandwiching at least a liquid crystal layer and the alignment film of the liquid crystal molecules, wherein the thickness of the alignment film is 0.1 μm.
m or less, at least one of the alignment films has a single layer thickness.
A liquid crystal display device comprising a water surface spread film of an organic polymer having a thickness of 0.003 μm or more. 2. A liquid crystal display device comprising at least a liquid crystal layer and a liquid crystal molecule alignment film sandwiched between a pair of transparent electrode substrates, at least one of which has a thickness of 0.1 μm.
m or less, in at least one of the alignment films, the organic polymer is aligned on the film surface in contact with the liquid crystal, and the thickness of the single layer is 0.003 μm.
A liquid crystal display device comprising the above water surface development film. 3. The liquid crystal layer is a nematic liquid crystal layer, and the major axis direction of liquid crystal molecules of the liquid crystal layer sandwiched between the upper and lower electrode substrates is twisted by 80 to 280 degrees between the upper and lower electrode substrates when the electric field is zero. The liquid crystal display element according to claim 1 or 2, wherein 4. The liquid crystal display device according to claim 1, wherein the liquid crystal layer is a ferroelectric liquid crystal composition layer. 5. The organic polymer alignment film is an alignment film made of an amic acid-based polymer, an imide-based polymer or a copolymer thereof, and the alignment film is any one of claims 1 to 4. Liquid crystal display element. 6. The liquid crystal display element according to claim 1, wherein the organic polymer alignment film is formed on an insulating layer and / or a coupling agent layer. . 7. The organic polymer alignment film is a film having a value of infrared dichroic ratio in the vertical direction and the horizontal direction of 1.05 or more, in any one of claims 1 to 6. The liquid crystal display element described. 8. A liquid crystal display device according to claim 1, wherein the electrode substrate is an electrode substrate which is a matrix type electrode. 9. An organic polymer solution is supplied on the surface of water, the solution is drawn in one direction to form a film, and the obtained water surface development film is formed in close contact with a predetermined site on the electrode substrate. A method for manufacturing a liquid crystal display element, which comprises the step of enclosing a liquid crystal in a liquid crystal cell created using. 10. The method for producing a liquid crystal display device according to claim 9, wherein the organic polymer solution is drawn at a drawing speed higher than the spontaneous development speed on the water surface to form a film. 11. A step of closely forming the film on the electrode substrate by a continuous operation in which a plurality of electrode substrates moving at the same speed as the take-up speed of the water surface development film are sequentially brought into contact with the film. 11. The method for manufacturing a liquid crystal display device according to claim 9, which is characterized in that.