JPH0850293A - Treatment of oriented film for liquid crystal display element and production of liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide a treating method to decrease the surface energy of an oriented film, a production method of a liquid crystal display device without display irregularity, and a liquid crystal display device without display irregularity. CONSTITUTION:In a method, in which a transparent electrode is formed on each of a pair of transparent substrates, and an oriented film comprised of an org. polymer material is formed on the transparent electrode and ribbed and, after these substrates are assembled to face each other through a spacer, a liquid crystal material is sealed between the substrates, after the oriented film is rubbed, the film is irradiated with soft X-rays in a gas. By this method, gas ions produced by irradiating the oriented film having high surface activity with soft X-rays are adsorbed to the oriented film and suppresses display irregularity due to adsorption of foreign matter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an alignment film for a liquid crystal display device, a method for manufacturing a liquid crystal display device, and a liquid crystal display device manufactured by this method with extremely small display unevenness. More specifically, an alignment film used for a liquid crystal display device is subjected to an alignment treatment and then irradiated with a soft X-ray in a gas. And a liquid crystal manufactured by the manufacturing method, which includes a step of irradiating a soft X-ray in a gas after that to reduce display unevenness of the liquid crystal display element and improve quality and yield. Regarding display element.

[0002]

2. Description of the Related Art Since liquid crystal display devices have a low driving voltage, are lightweight and have high image quality, they are actively being introduced into the field of office automation equipment such as personal computers and word processors. Since liquid crystal display elements used for these purposes are required to display characters and drawings, it is inevitably necessary to manufacture high-quality liquid crystal display elements that are in the direction of large screens, large numbers of pixels, and high definition and have no display defects. A method is needed. As a liquid crystal display device, a twisted nematic mode device in which the alignment direction of nematic liquid crystal molecules is twisted by 90 degrees on the surface of a pair of upper and lower electrode substrates is generally used. The twist angle of the liquid crystal molecule is 180
A large one up to 300 degrees is also known as a super twisted nematic mode. In recent years, in order to perform matrix display, color display, etc., an active matrix type twist using an MIM (metal-insulation phase-metal) element or a TFT (field effect thin film transistor) element for turning on and off a large number of pixel electrodes. The development of nematic mode liquid crystal display devices has become popular.

[0003]

Organic materials such as polyimide and polyamide are mainly used for the alignment film used in such a liquid crystal display device. The polyimide-based alignment film is a material having a large surface polarity, and since the surface of the alignment film is activated particularly after the alignment treatment, it is easy to adsorb ionic or polar impurities. Then, in the portion where the impurities are adsorbed, the orientation ability of the alignment film is changed, the impurities act as a capacitor, or the state of the electric double layer that may be generated at the interface between the liquid crystal and the alignment film is changed. Then, it causes display unevenness of the liquid crystal display element for image display. The display unevenness of this liquid crystal display element is caused by unevenness in brightness, contrast or chromaticity present in a small part of the screen.
There is a wide variety of things, such as those that are spread over the entire screen. For example, (1) uneven dust generated around the minute dust mixed in the liquid crystal display element, (2) uneven seal agent around the seal agent of the liquid crystal display element, (3) liquid crystal injection port of the liquid crystal display element Examples include semi-circular irregularities that occur around the edge, and (4) irregular cleaning due to impurities mixed in during the cleaning of the liquid crystal display element.

In recent years, minute dust in the air, especially dust unevenness caused by fatty acids generated by the human body, has become a serious problem. With the progress of cleaning technology, it has become rare for large dust to be mixed in, but it is still difficult to completely remove minute dust. It is considered that even if a minute dust of about 1 micron enters, an ionic or polar impurity is eluted from the dust, which affects the surroundings and appears remarkably as visible unevenness. recently,
In order to remove this minute dust, cleaning treatment with pure water or an organic solvent is performed after the orientation treatment.
In order to increase the cleaning power, it is common to combine a physical cleaning method such as brushing, jet spray or ultrasonic cleaning, and it is effective for removing minute dust. However, a trace amount of impurities are also contained in the cleaning liquid, and it is still difficult to completely remove them. Then, uneven cleaning caused by impurities contained in the cleaning liquid has become a new problem. On the other hand, in addition to an attempt to reduce impurities mixed in the device, it has been proposed to control the adsorption ability of the alignment film to reduce the influence of impurities.
Japanese Patent Application Laid-Open No. 1-185617 discloses a method of preventing the display unevenness of a liquid crystal panel by suppressing the adsorption of impurities on the surface of the alignment film by fluorinating the surface of the alignment film. However, the method of the publication is effective in suppressing the adsorption of impurities, but since the surface state of the alignment film is extremely changed by the fluorination treatment, the alignment ability of the alignment film is also deteriorated. There was such a problem.

The force acting when the ionic or polar impurities are adsorbed on the surface of the alignment film may be hydrogen bond, dipole-dipole interaction, Coulomb-Coulomb interaction, or the like. In general, such interactions are greater between those having a larger polarity, and it is considered that the adsorption of impurities can be suppressed by reducing the polar component of the surface energy of the alignment film. As a method of reducing the surface energy of the alignment film, (1) a method of adjusting the molecular structure of the alignment film or adding an additive into the alignment film, (2) a treatment with a surface treatment agent after forming the alignment film And (3) a method of irradiating with ultraviolet light in an atmosphere containing oxygen or ozone after the orientation treatment. Among these, the methods (1) and (2) are not preferable because various characteristics of the alignment film itself, such as the alignment ability and the electrical characteristics, are significantly changed.
The method (3) is not preferable because the alignment film is deteriorated by ultraviolet irradiation.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and is a method for treating an alignment film for a liquid crystal display element, which reduces the surface energy of the alignment film. And a manufacturing method capable of preventing display unevenness of a liquid crystal display element by using the method for treating an alignment film, and a liquid crystal display element having no display unevenness manufactured by this method. . The method for treating an alignment film for a liquid crystal display device according to the present invention comprises: rubbing an alignment film made of an organic polymer material coated on a transparent substrate provided with a transparent electrode, and then soft X
The feature is that the line is irradiated for 2 seconds or more. That is,
When a soft X-ray having a long wavelength is irradiated, gas ions generated by the ionization action are adsorbed on the alignment film and the polar component of the surface energy of the alignment film is reduced, so that display unevenness of the liquid crystal display element can be prevented. This can be understood as a phenomenon in which the gas ions generated by the soft X-ray irradiation are adsorbed by the adsorption sites on the surface activated by the alignment treatment, and the surface cannot adsorb further impurities.

The atmosphere for irradiating the soft X-ray of the present invention is not limited as long as it is in a gas. Preferred gases include oxygen, nitrogen, carbon dioxide, water vapor, helium, neon, argon and mixed gases thereof. The effect of reducing the surface energy of the substance by the soft X-ray irradiation in the present invention is not limited to the surface treatment of the alignment film for a liquid crystal display element, but can be applied to essentially any substance. The long-wavelength soft X-ray used in the present invention has a low energy, and therefore has a very low substance permeability. This is a material that can be easily shielded with a transparent vinyl chloride plate or the like, does not pose a danger to the human body, and is preferable in terms of safety management. Furthermore, it is considered to be advantageous in that the alignment film is not deteriorated.

The soft X-ray irradiation apparatus used in the present invention has a soft X-ray energy of 4 to 9.5 kiloelectronvolts (ke).
V) is not particularly limited as long as the output can be stably controlled. The soft X-ray irradiation time is 2 seconds or more, preferably 5 to 300 seconds. If the irradiation time is less than 2 seconds, the effect of reducing the surface energy due to the soft X-ray irradiation becomes small. The soft X-ray irradiation distance is not particularly limited, but is usually adjusted to 1500 mm or less, preferably 10 to 400 mm.

In the method for producing a liquid crystal display device of the present invention, transparent electrodes are provided on a pair of transparent substrates, an alignment film made of an organic polymer substance is formed on the transparent electrodes, and the alignment film is rubbed. In a method for manufacturing a liquid crystal display device, which includes a step of assembling the substrates so as to face each other with a spacer interposed therebetween, a liquid crystal display device is rubbed, and then the alignment film is exposed to a soft X-ray in a gas for 2 seconds. It is characterized in that the above irradiation is performed. In the method for manufacturing a liquid crystal display element of the present invention, soft X
It is possible to perform a cleaning treatment with a cleaning liquid before the irradiation of the rays, or to perform a cleaning treatment after the irradiation of the soft X-rays. Examples of the cleaning method include brushing, jet spray, steam cleaning and ultrasonic cleaning. These methods may be used alone or in combination. As the cleaning liquid, pure water or various alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, aromatic hydrocarbons such as benzene, toluene and xylene, halogen solvents such as methylene chloride, ketones such as acetone and methyl ethyl ketone are used. It can be used, but is not limited thereto. Of course, as these cleaning liquids, those which are sufficiently purified and have few impurities are used.

In the present invention, a polyimide resin is preferably used as the material of the alignment film. As the polyimide, a polyimide represented by the general formula (1)

[0011]

[Chemical 3]

(In the formula, R ₁ represents a tetravalent, alicyclic, aromatic or heterocyclic hydrocarbon residue, which may have a group such as halogen in the group, and R ₂ represents a divalent group. Which has a structural unit represented by a hydrocarbon residue of, -O-, -S-, or a halogen atom or a cyano group can also be contained in the group). Used. That is, as the polyamic acid, a tetracarboxylic dianhydride having an aromatic ring such as pyromellitic dianhydride, or an alicyclic tetracarboxylic dianhydride such as cyclobutanoic acid tetracarboxylic dianhydride, and diamino A polyamic acid or the like obtained by reacting a compound is preferably used.

Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 2,2', 3,3'-biphenyltetracarboxylic acid. Acid dianhydride, 2,3,3 ', 4'
-Biphenyltetracarboxylic dianhydride, 3,3 ',
4,4'-benzophenone tetracarboxylic dianhydride,
2,3,3 ', 4'-benzophenone tetracarboxylic dianhydride, 2,2', 3,3'-benzophenone tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) sulfonic acid dianhydride And aromatic tetracarboxylic dianhydrides such as 1,2,5,6-naphthalene tetracarboxylic dianhydride and 2,3,6,7-naphthalene tetracarboxylic dianhydride, and alicyclic The formula tetracarboxylic acid includes cyclobutane, cyclohexane, cyclooctane,
Examples thereof include dianhydrides of alicyclic tetracarboxylic acids having a ring such as bicyclooctane and those having the following structural formula.

[0014]

[Chemical 4]

The diamino compound which is the other raw material of the polyamic acid is 1,1-bis [4- (4-
Aminophenoxy) phenyl] cyclohexane, 1,1
-Bis [4- (4-aminophenoxy) phenyl] -4
-Methylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-ethylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-propylcyclohexane, 1, 1-bis [4- (4-aminophenoxy) phenyl] -4-butylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-pentylcyclohexane,
1,1-bis [4- (4-aminophenoxy) phenyl] -4-hexylcyclohexane, 1,1-bis [4
-(4-aminophenoxy) phenyl] -4-heptylcyclohexane, 1,1-bis [4- (4-aminophenoxy) phenyl] -4-octylcyclohexane,

2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4]
-(4-aminophenoxy) phenyl] pentane, 2,
2-bis [4- (4-aminophenoxy) phenyl] hexane, 2,2-bis [4- (4-aminophenoxy)
Phenyl] heptane, 2,2-bis [4- (4-aminophenoxy) phenyl] octane, 2,2-bis [4-
(4-Aminophenoxy) phenyl] nonane, 2,2-
Bis [4- (4-aminophenoxy) phenyl] decane, 2,2-bis [4- (4-aminophenoxy) phenyl] dodecane, 1,1-bis [4- (4-aminobenzyl) phenyl] cyclohexane, 1,1-bis [4-
(4-Aminobenzyl) phenyl] -4-methylcyclohexane, 1,1-bis [4- (4-aminobenzyl)
Phenyl] -4-ethylcyclohexane, 1,1-bis [4- (4-aminobenzyl) phenyl] -4-propylcyclohexane, 1,1-bis [4- (4-aminobenzyl) phenyl] -4-butyl Cyclohexane, 1,
1-bis [4- (4-aminobenzyl) phenyl] -4
-Pentylcyclohexane, 1,1-bis [4- (4-
Aminobenzyl) phenyl] methane,

4,4'-diaminophenyl ether,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, 4,4'-di (meta-aminophenoxy) diphenyl sulfone, 4,4 '-(para-amino (Phenoxy) diphenyl sulfone, ortho-phenylenediamine, meta-phenylenediamine, para-phenylenediamine, benzidine, 2,2'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-
Diaminodiphenyl-2,2'-propane, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 2,
There are aromatic diamino compounds such as 2-bis [4- (4-aminophenoxy) phenyl] hexamethylpropane as well as alicyclic diamino compounds such as 1,4-diaminocyclohexane and 4,4′-diaminodicyclohexylmethane. However, the tetracarboxylic dianhydride and diamino compound, which are the raw materials for the alignment film used in the present invention, are not limited to these. Further, the acid anhydride and the diamino compound may be used in combination of two or more kinds thereof.

In order to provide the polyimide alignment film according to the present invention on a substrate, since the polyimide compound is generally insoluble in a solvent, a polyamic acid obtained by condensing the precursor tetracarboxylic dianhydride and the diamino compound. Is dissolved in a solvent, coated on a substrate, and then heated to imidize. Specifically, polyamic acid may be N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF), dimethylsulfoxide (DMSO), butylcellosolve (BC), ethylcarbitol, propylene glycol. It is dissolved in a solvent such as monobutyl ether or 3-methyl-3-methoxybutanol to prepare a 0.1 to 30 wt% solution, preferably 1 to 10 wt% solution, and this solution is applied by a brush coating method, a dipping method, A spin coating method, a spray method, a printing method or the like is applied to form a coating film on the substrate. After forming the coating film, 50 to 150 ° C., preferably 80 to 1
After evaporating the solvent at 20 ° C., heat treatment is performed at 150 ° C. to 400 ° C., preferably 180 ° C. to 280 ° C., and a dehydration ring closure reaction is performed to provide a liquid crystal alignment film made of a polybenzylimide polymer film. . When the adhesion of the obtained polymer film to the substrate is not good, the adhesion is improved by forming the polymer film after performing surface treatment with the silane coupling agent on the substrate surface in advance. . After the organic polymer film is provided on the substrate surface in this manner, the coated surface is rubbed with a cloth in a certain direction to obtain a liquid crystal alignment film.

On this substrate, a transparent electrode, specifically IT
A transparent electrode such as O (indium oxide-tin oxide) is formed. Furthermore, an insulating film may be formed under this electrode for the purpose of preventing the elution of alkali from the substrate,
Further, a polarizing plate, a color filter film, a light transmission preventing film or the like may be provided in the cell. As these other cell constituents, any suitable one can be used according to the construction of the conventional liquid crystal element. A cell is formed using such a substrate, liquid crystal is injected, and then the injection port is sealed. Alternatively, the liquid crystal display element may be prepared by spraying the liquid crystal on the substrate, stacking the substrates and sealing the liquid crystal so as not to leak.
The liquid crystal used in the liquid crystal display element of the present invention, a liquid crystal added with a dichroic dye in addition to a normal nematic liquid crystal,
In addition to the ferroelectric liquid crystal, any liquid crystal that can be used for a normal display element can be used. As an example of the liquid crystal component that can be used in the present invention, a liquid crystal compound represented by the general formula (2) and a liquid crystal compound represented by the general formula (3) described below can be shown.

[0020]

Embedded image

(In the formula, R ₁ represents a linear alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and R ₂ represents a linear alkyl group having 1 to 10 carbon atoms. alkyl group or alkyloxy group, -CN, fluorine atom, chlorine atom, -CF _3, -CHF _2, represents -OCF ₃ or -OCHF _2, S ₁ and S ₂ represents a hydrogen atom, a fluorine atom, a chlorine atom, - CF _3, -CHF _2, represents -OCF ₃ or -OCHF _2, it may be the being the same or different, Z ₁ is, -COO -, - CH ₂
CH ₂ —, —C≡C— or a single bond, and A ₁ is

[0022]

[Chemical 6] Represents ),

[0023]

[Chemical 7]

(In the formula, R ₃ is R in the general formula (2).
₁ has the same meaning as R ₁ , R ₄ has the same meaning as R ₂ in the general formula (2), and S ₃ and S ₄ have the same meaning as S ₁ and S ₂ in the general formula (2) and are the same as each other. May be present or different, Z ₂ and Z ₃ may be the same or different from each other, and have the same meaning as Z _{1 in the} general formula (2), A ₂ and A ₃ are the same as those in the general formula (2). It has the same meaning as A _{1 in} (2), and these may be the same or different from each other. The components of these liquid crystal compositions may be a single component or a mixture of a plurality of components. As the liquid crystal mixture used in the liquid crystal display device of the present invention, compounds other than those described above can be used unless the object of the invention is impaired.

A more preferred embodiment of the present invention is as follows (a)
It is described in each item of (A) After rubbing a polyimide-based alignment film formed on a transparent substrate provided with a transparent electrode, the alignment film is soft X in air.
A method for treating an alignment film, which comprises irradiating a ray for a certain period of time between 5 and 300 seconds. (A) The method for treating an alignment film in which the energy of soft X-rays is 4 to 9.5 kiloelectronvolts (keV) in the preceding paragraph. (C) The method for treating an alignment film according to the item (A), wherein the distance between the alignment film and the soft X-ray source is 10 to 400 mm. (D) In the above item (a), the energy of the soft X-ray is 4
A method for treating an alignment film, which comprises irradiating a soft X-ray with an alignment film placed at a position 10 to 400 mm away from a radiation source of ˜9.5 keV. (E) A transparent electrode is provided on a pair of transparent substrates, a polyimide-based alignment film is formed on the transparent electrodes, the alignment film is subjected to a rubbing treatment, and the substrates are assembled to face each other via a spacer, and then a liquid crystal is formed. In a method of manufacturing a liquid crystal display element, which includes a step of encapsulating a material, after rubbing the alignment film, the alignment film is irradiated with soft X-rays for 5 to 300 seconds in the air. Production method. (F) In the preceding paragraph, the energy of soft X-ray is 4 to 9.5.
A method of manufacturing a liquid crystal display device having a kilo electron volt (keV). (G) In the above item (e), 10 to 40 from the soft X-ray source.
A method of manufacturing a liquid crystal display device, which comprises arranging an alignment film at a distance of 0 mm and irradiating with soft X-rays. (H) In the above item (e), the soft X-ray energy is 4
A method for manufacturing a liquid crystal display device, comprising arranging an alignment film at a position 10 to 400 mm away from a radiation source of ˜9.5 keV and irradiating with soft X-rays. (K) A transparent electrode is provided on a pair of transparent substrates, a polyimide-based alignment film is formed on the transparent electrodes, the alignment film is rubbed, and the substrates are assembled facing each other via a spacer. In a liquid crystal display device prepared by enclosing a liquid crystal mixture containing at least one compound represented by the general formula (1) or (2), the alignment film is softened for 5 to 300 seconds in air after rubbing treatment. A liquid crystal display device characterized by being irradiated with X-rays. (K) In the preceding paragraph, the energy of soft X-rays is 4 to 9.5.
A liquid crystal display element that has been irradiated with soft X-rays of kilo electron volts (keV). (S) In the above item (X), the energy of the soft X-ray is 4
10 from a source that is ~ 9.5 kiloelectronvolts (keV)
A liquid crystal display element that is exposed to soft X-rays with an alignment film at a distance of 400 mm.

[0026]

The present invention will be described in more detail below by showing Examples and Comparative Examples, but the present invention is not limited to these Examples. The method of measuring the surface energy used in these examples is as follows. The surface energy of the alignment film was measured by calculating the contact angle using two liquids whose polar component and dispersion component of the surface energy are known. The value of the contact angle is related to the surface energy from the following equation. The case where a liquid having a surface energy γ _L on the solid surface (the surface energy of the solid is γ _S ) is in equilibrium at the contact angle θ is shown. In this system, Y
The expression of oung is established. γ _S = γ _SL + γ _L cos θ where γ _SL is the energy between solid and liquid, and is related to the interaction force at the interface. The work of adhesion is represented by Wa = γ _S + γ _L − γ _SL , and when combined with the formula, Wa = γ _L (1 + cos θ). Here, when the surface energy is divided into the dispersion component (γ ^D ) and the polar component (γ ^P ) based on the idea of Forkes et al., Γ = γ ^D + γ ^P. Assuming that the dispersion component of the surface energy interacts only with the dispersion component and the polar component with the polar component, Wa = (γ _S ^D γ _L ^D ) ^1/2 + (γ _S ^P γ _L ^P ) ^1/2 From the formula, γ _L (1 + cos θ) = (γ _S ^D γ _L ^D ) ^1/2 + (γ _S ^P γ _L ^P ) ^1/2 From this, we use two types of liquids whose surface energy dispersion component and polar component are known. Then, by measuring the contact angle, the dispersion component and the polar component of the surface energy of the substrate can be calculated. In the following examples, pure water (H ₂ O) and ethylene glycol (E) with known surface energy values are used.
The surface energy was determined using G). The values of the dispersion component and the polar component of the surface energy used are as follows. γ _L ^D γ _L ^P γ _L H ₂ O 22.0 50.2 72.2 (ergcm ^-2 ) EG 29.3 19.0 48.3 (ergcm ^-2 )

Example 1 A polyamic acid solution was obtained by polymerizing 3.46 g of 4,4'-diaminophenyl ether, 4.36 g of pyromellitic dianhydride and 0.11 g of paraaminophenyltrimethoxysilane. Add butyl cellosolve (BC) to this solution.
And a N-methyl-2-pyrrolidone (NMP) mixture at a weight ratio of 1: 1 were added to dilute the polyamic acid to 3% by weight, and then this solution was placed on a transparent glass substrate having an ITO electrode on one side. It was applied by a spin coating method (spinner method). The coating conditions were 3000 rpm and 15 seconds. After the coating film is dried at 100 ° C. for 10 minutes, the temperature is raised to 200 ° C. in an air oven for 1 hour, and heat treatment is performed at 200 ° C. for 90 minutes, and a polyimide film having a film thickness of about 600 Å is formed on a transparent electrode. Obtained on the provided substrate. A total of 5 alignment films were obtained by the same operation, and used for the next test.
After the alignment treatment using a rubbing cloth on the obtained alignment film,
The four substrates were irradiated with soft X-rays from a position 50 mm in the direction perpendicular to the film surface using a soft X-ray irradiation device (C4870) manufactured by Hamamatsu Photonics KK. The soft X-ray irradiation time is 6
The test was conducted under the conditions of seconds, 15 seconds, 30 seconds, and 60 seconds. The energy of the soft X-ray irradiator was 6 keV, and its tube voltage and tube current were 9.5 kV and 0.2 mA, respectively. The surface energy of the film formed by this method was promptly measured at room temperature after the soft X-ray irradiation treatment. The surface energy of the film sharply decreased with the soft X-ray irradiation time. The contact angles of pure water and ethylene glycol of the film after the soft X-ray irradiation time of 60 seconds were 67.4 degrees and 51.8 degrees, respectively, and the value of the polar component of the surface energy was 23.7 ergcm ^-2 .

The polyimide film prepared in the same manner was irradiated with soft X-rays for 60 seconds, and the substrate was subjected to ultrasonic cleaning treatment in pure water and drying treatment. Using this substrate, a liquid crystal cell with a cell thickness of 6 microns and a twist angle of 240 ° was assembled, and liquid crystal for STN manufactured by Chisso Corporation (product name LIX
ON 4032-000XX) was enclosed. 12 after inclusion
Isotropic treatment was performed at 0 ° C. for 30 minutes, and the liquid crystal element was obtained by gradually cooling to room temperature. In the same manner, 10 liquid crystal elements were prepared, and the obtained elements were energized to examine the presence or absence of display unevenness. A slight display unevenness was observed in the three elements, but in the remaining seven elements. No display unevenness was observed.

Comparative Example 1 Ten liquid crystal display elements were prepared in the same manner as in Example 1 except that soft X-ray irradiation was not performed. The contact angles of pure water and ethylene glycol of the formed film were 64.6 degrees and 51.4 degrees, respectively, and the value of the polar component of the surface energy was 28.3 ergcm ^-2 .
Further, when the presence of display unevenness was examined by energizing the obtained 10 elements, display unevenness was observed in all the elements, and particularly noticeable display unevenness was observed in the 7 elements. 1 obtained from Example 1 and Comparative Example 1,
The relationship between the soft X-ray irradiation time and the polar component of surface energy is shown. It can be seen from FIG. 1 that the sample after the soft X-ray irradiation (Example 1) has a smaller surface energy than the sample before the soft X-ray irradiation (Comparative Example 1).

Example 2 Using 50 g of dehydrated and purified NMP as a solvent, 7.43 g of 1,1-bis [4- (4-aminobenzyl) phenyl] -4-cyclohexane and 3.69 of pyromellitic dianhydride were used.
g was reacted with cooling. After 1 hour, 0.11 g of para-aminophenyltrimethoxysilane was added, and the mixture was reacted at 20 ° C for 1 hour. After that, the reaction liquid was NMP 51.1 g.
A transparent solution containing 10% by weight of polyamic acid was obtained by diluting with. The viscosity of this solution at 25 ° C is 18
It was 70 centipoise. Using a mixed solvent of BC and NMP (1: 1), this solution contains 3% by weight of polyamic acid.
After diluting so as to have the above composition, a spin coating method (spinner method) was applied on a transparent glass substrate having an ITO electrode on one surface. The coating conditions were 4500 rpm and 15 seconds. After the coating film is dried at 100 ° C for 10 minutes, the temperature is raised to 200 ° C over 1 hour in an air oven, and heat treatment is performed at 200 ° C for 90 minutes to provide a glass having a polyimide film with a thickness of about 600 Å. Five substrates were obtained. After aligning the obtained alignment film with a rubbing cloth, a soft X-ray irradiator (C487 manufactured by Hamamatsu Photonics KK) was applied to the four substrates.
0) was used to irradiate soft X-rays from a position 50 mm in the direction perpendicular to the film surface. The soft X-ray irradiation time is 6 seconds, 15 seconds,
The test was conducted under each condition of 30 seconds and 60 seconds. The energy of the soft X-ray irradiator was 6 keV, and its tube voltage and tube current were 9.5 kV and 0.2 mA, respectively.

The surface energy of the film formed by this method was promptly measured at room temperature after the soft X-ray irradiation treatment. The surface energy of the film sharply decreased with the soft X-ray irradiation time. The contact angles of pure water and ethylene glycol of the film after the soft X-ray irradiation time of 60 seconds are 75.0 degrees and 54.2 degrees, respectively, and the value of the polar component of the surface energy is 1.
It was 3.8 ergcm ^-2 . The substrate obtained by irradiating the rubbing-treated polyimide film under the same conditions with soft X-rays for 60 seconds as described above was subjected to ultrasonic cleaning in pure water and dried. Using this substrate, 10 liquid crystal cells with a cell thickness of 6 μm and a twist angle of 240 ° were assembled, and liquid crystal for STN manufactured by Chisso Corporation (product name LIXON 4032-
000XX) was enclosed. After encapsulation, isotropic treatment was performed at 120 ° C. for 30 minutes, and the liquid crystal element was obtained by gradually cooling to room temperature. When the liquid crystal display elements thus obtained were energized and examined for display unevenness, no display unevenness was observed in any of the elements.

Comparative Example 2 Ten liquid crystal elements were prepared in the same manner as in Example 2 except that soft X-ray irradiation was not performed. The contact angles of pure water and ethylene glycol of the alignment film formed by this method were 73.4 degrees and 60.6 degrees, respectively, and the value of the polar component of the surface energy was 21.1 ergcm ^-2 . Moreover, when the presence of display unevenness was examined by energizing the obtained elements, display unevenness was observed in the eight elements,
In particular, remarkable uneven display was observed in the five elements.

FIG. 2 shows the relationship between the soft X-ray irradiation time and the polar component of the surface energy obtained in Example 2 and Comparative Example 2. From FIG. 2, the sample after soft X-ray irradiation (Example 2)
It can be seen that the surface energy is smaller than that of the sample not irradiated with soft X-ray (Comparative Example 2).

Example 3 8.06-g 2,2-bis [4- (4-aminophenoxy) phenyl] propane and pyromellitic dianhydride 4.
36 g and para-aminophenyltrimethoxysilane.
11 g was polymerized to obtain a polyamic acid solution. A 1: 1 mixed solution of butyl cellosolve and NMP was added to this solution to dilute the polyamic acid to 3% by weight, and then applied by spin coating (spinner method) on a transparent glass substrate having an ITO electrode on one side. . The coating conditions are 3000 rpm,
It was 15 seconds. After drying at 100 ° C for 10 minutes after coating,
The temperature is raised to 200 ° C over 1 hour in an air oven, and heat treatment is performed at 200 ° C for 90 minutes to obtain a film thickness of about 600.
Glass substrate 5 with angstrom polyimide film
Got a piece. The alignment film obtained was subjected to an alignment treatment using a rubbing cloth, and then soft X-rays were applied to the four substrates using a soft X-ray irradiation device (C4870) manufactured by Hamamatsu Photonics Co., Ltd. from a position of 50 mm in a direction perpendicular to the film surface. Irradiated for 2 seconds. The energy of the soft X-ray irradiator was 6 keV, and its tube voltage and tube current were 9.5 kV and 0.2 mA, respectively. The surface energy of the film formed by this method was promptly measured at room temperature after the soft X-ray irradiation treatment. The surface energy of the film sharply decreased with the soft X-ray irradiation time. Soft X
The contact angles of pure water and ethylene glycol of the film after the irradiation time of 60 seconds are 71.0 degrees and 55.2 degrees, respectively, and the value of the polar component of the surface energy is 20.5 ergc.
m ^-2 . The obtained polyimide film was subjected to ultrasonic cleaning treatment in pure water and drying treatment. Using this substrate, a liquid crystal cell with a cell thickness of 6 microns and a twist angle of 240 ° was assembled, and a liquid crystal for STN manufactured by Chisso Co. (product name LIX
ON 4032-00XX) was enclosed. 120 after encapsulation
An isotropic treatment was performed at 30 ° C. for 30 minutes, and the liquid crystal display device was obtained by gradually cooling to room temperature. Similarly, 10 liquid crystal elements were prepared at the same time, and the obtained elements were energized to examine the presence or absence of display unevenness. A slight display unevenness was observed in the two elements, but the remaining 8 elements were observed. No display unevenness was observed in.

Comparative Example 3 Ten liquid crystal elements were prepared in the same manner as in Example 3 except that soft X-ray irradiation was not performed. The contact angles of pure water and ethylene glycol of the formed film were 65.6 degrees and 50.4 degrees, respectively, and the value of the polar component of the surface energy was 25.6 ergcm ^-2 . Also,
When the presence of display unevenness was examined by energizing the obtained elements, display unevenness was observed in all the elements.
Significant display unevenness was observed in the one element.

Example 4 1,1-Bis [4- (4-aminophenoxy) phenyl] -4-trans-4-ethylcyclohexane 7.0
5 g, pyromellitic dianhydride 2.18 g, cyclobutanetetracarboxylic acid 0.65 g and para-aminophenyltrimethoxysilane 0.09 g were polymerized to obtain a polyamic acid solution. To this solution was added a mixed solution of butyl cellosolve and NMP in a weight ratio of 1: 1 to add polyamic acid to the solution.
After diluting to a weight percentage, it was applied by spin coating (spinner method) on a transparent glass substrate having an ITO electrode on one side.
The coating conditions were 3000 rpm and 15 seconds. After coating 1
After drying at 00 ° C for 10 minutes, the temperature was raised to 200 ° C over 1 hour in an air oven, and heat treatment was performed at 200 ° C for 90 minutes to obtain a glass substrate provided with a polyimide film having a thickness of about 600 Å. It was The obtained alignment film was subjected to an alignment treatment using a rubbing cloth, and then a soft X-ray irradiation device (C4870) manufactured by Hamamatsu Photonics K.K. . The energy of the soft X-ray irradiator was 6 keV, and its tube voltage and tube current were 9.5 kV and 0.2 mA, respectively. The surface energy of the film formed by this method was promptly measured at room temperature after the soft X-ray irradiation treatment. The contact angles of pure water and ethylene glycol of this film were 69.8 degrees and 54.9 degrees, respectively, and the value of the polar component of the surface energy was 22.3 ergcm ^-2 .

The obtained polyimide film was subjected to ultrasonic cleaning treatment in pure water and drying treatment. Using this substrate, a liquid crystal cell with a cell thickness of 6 microns and a twist angle of 240 ° was assembled, and a liquid crystal for STN manufactured by Chisso Co. (product name LIX
ON 4032000XX) was enclosed. 12 after inclusion
Isotropic treatment was performed at 0 ° C. for 30 minutes, and the liquid crystal element was obtained by gradually cooling to room temperature. When 10 liquid crystal display elements were prepared for the same purpose and the resulting elements were energized to examine the presence or absence of display unevenness, a slight display unevenness was observed in the three elements, but the remaining 7 No display unevenness was observed in the device.

Comparative Example 4 Ten liquid crystal elements were prepared in the same manner as in Example 4 except that soft X-ray irradiation was not performed. The contact angles of pure water and ethylene glycol of the film formed by this method were 65.0 degrees and 50.9 degrees, respectively, and the value of the polar component of the surface energy was 27.1 ergcm ^-2 .
When the liquid crystal display device thus obtained was energized to examine the presence or absence of display unevenness, display unevenness was observed in all the devices, and particularly in eight devices, remarkable display unevenness was observed.

[0039]

As described above, according to the method of irradiating the alignment film with the soft X-ray in the gas after performing the alignment treatment,
It is possible to reduce the display unevenness of the liquid crystal display element, improve the display quality of the liquid crystal display device, and improve the product yield.

[Brief description of drawings]

1 shows the relationship between the soft X-ray irradiation time and the polar component of surface energy obtained from Example 1 and Comparative Example 1. FIG.

FIG. 2 shows the relationship between the soft X-ray irradiation time and the polar component of surface energy obtained in Example 2 and Comparative Example 2.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 2, 1995

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title: Method for treating alignment film for liquid crystal display device and method for manufacturing liquid crystal display device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C09K 19/34 G02F 1/13 101 (72) Inventor Naruo Murata 545-9 Shiizu, Ichihara-shi, Chiba ( 72) Inventor Makoto Kono 11400-1078 Harayama, Tamagawa, Chino City, Nagano Prefecture Inside the Iinuma Gauge Manufacturing Co., Ltd.

Claims (8)

[Claims] 1. An alignment film made of an organic polymer material formed on a transparent substrate provided with a transparent electrode is rubbed, and then the alignment film is irradiated with a soft X-ray for 2 seconds or more in a gas. And a method for treating an alignment film for a liquid crystal display device. 2. The soft X-ray energy is 4 to 9.5 keV.
The method for treating an alignment film for a liquid crystal display device according to claim 1, wherein 3. The distance from the alignment film to the soft X-ray source is 150.
It is 0 mm or less, The processing method of the alignment film for liquid crystal display elements of Claim 1 characterized by the above-mentioned. 4. A transparent electrode is provided on a pair of transparent substrates, and an alignment film made of an organic polymer substance is formed on the transparent electrodes.
In a method of manufacturing a liquid crystal display device, which comprises a step of rubbing the alignment film, assembling the substrates so as to face each other with a spacer interposed therebetween, and then encapsulating a liquid crystal material, the alignment film is rubbed and then aligned in a gas. A method for manufacturing a liquid crystal display device, which comprises irradiating the film with soft X-rays for 2 seconds or more. 5. The soft X-ray energy is 4 to 9.5 keV.
The method for manufacturing a liquid crystal display element according to claim 4, wherein 6. The distance from the alignment film to the soft X-ray source is 150.
It is 0 mm or less, The manufacturing method of the liquid crystal display element of Claim 4 characterized by the above-mentioned. 7. A transparent electrode is provided on a pair of transparent substrates, and an alignment film made of an organic polymer substance is formed on the transparent electrodes,
In the liquid crystal display device produced by rubbing the alignment film and facing the substrates with spacers in between, and assembling the liquid crystal material, the alignment film is subjected to the soft X-ray irradiation after the rubbing process. A liquid crystal display device characterized in that 8. The liquid crystal material is represented by the general formula (2) or the general formula (3): (In these formulas, R ₁ and R ₃ are each independently a linear alkyl group having 1 to 10 carbon atoms or 2-1 to 2 carbon atoms.
0 alkenyl group, R ₂ and R ₄ are each independently a linear alkyl group or alkyloxy group having 1 to 10 carbon atoms, —CN, fluorine atom, chlorine atom, —CF ₃ , —
CHF ₂ , —OCF ₃ or —OCHF ₂ is replaced with S ₁ , S ₂ ,
S ₃ and S ₄ are each independently a hydrogen atom, a fluorine atom,
Chlorine _{atom, -CF 3, -CHF 2, -OCF} 3 or -O
CHF ₂ , Z ₁ , Z ₂ and Z ₃ are independently -CO
_{O -, - CH 2 CH 2} -, - C≡C- or represents a single bond, respectively, A _1, A ₂ and A ₃ each independently embedded image A liquid crystal display device according to claim 7, which is a liquid crystal mixture containing at least one compound represented by