JP3537709B2 - Liquid crystal alignment film and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide liquid crystal alignment layer manufactured with a new chemical adsorption substance with excellent productivity, being uniformly and toughly fixed to a substrate, being excellent in thermal stability and controllability of aligmnent, besides being transparent and realizing a wide viewing angle and having layer thickness of a nanometer level and a liquid crystal display device utilizing the same. SOLUTION: The liquid crystal alignment layer incorporated in the liquid crystal display device is composed of a monolayer thin film consisting of adsorptive molecules having a chemical bond unit expressed by the formula chemically adsorbed to the substrate surface on which electrodes are formed with a siloxane bond. Furthermore, the pretilt angle and/or the pretilt azimuth of the liquid crystal molecules contained inside the cell gap are/is controlled by the incline of the long axis of the adsorptive molecules with respect to the substrate surface and/or its orientation bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal alignment film using a chemically adsorbed substance capable of forming a monomolecular thin film and a liquid crystal display device using such a liquid crystal alignment film.

[0002]

2. Description of the Related Art In a liquid crystal display device, a pair of substrates having transparent electrodes arranged in a matrix and a liquid crystal alignment film formed on the transparent electrodes is provided with a fixed gap with the liquid crystal alignment film surface inside. And a liquid crystal is sealed in the gap. This general manufacturing method will be described using a color liquid crystal display device as an example. A first glass substrate on which a pixel electrode and a thin film transistor (TFT) array are formed, and a second glass substrate on which a red-blue-green color filter is formed and on which a common transparent electrode is formed are manufactured. . A liquid crystal alignment film is formed on the surfaces of the first and second substrates, and the film is rubbed to impart liquid crystal alignment. Next, the two substrate surfaces are opposed to each other with a spacer interposed with the coating surface inside, and the periphery of the substrate is bonded to form an empty cell (panel structure).

[0003] For example, twisted nematic (TN) liquid crystal is injected into the empty cell and sealed to form a liquid crystal cell. A polarizing plate is arranged on both outer surfaces of the cell, and a backlight is arranged outside the first electrode to complete a liquid crystal display device as an optical display device.

In the liquid crystal display device having the above-described structure, the inter-electrode voltage is controlled by the switching element TFT to change the alignment state of the liquid crystal, and the light transmission is turned on / off in pixel units.
FF to display any video. Therefore, the alignment film that regulates the alignment state of the liquid crystal when no voltage is applied plays an extremely important role that directly affects the display performance of the device.

As a coating material for a liquid crystal alignment film, a polyimide film has been widely used conventionally. This is because the polyimide film is excellent in affinity with liquid crystal, heat resistance, substrate adhesion, and the like. As a method for producing a polyimide film, a solution obtained by dissolving a polyamic acid, which is a precursor polymer of a polyimide, in an organic solvent such as xylene is spin-coated on a substrate, and then baked to imidize the polyamic acid to obtain a polyimide film. Method, and polyimide itself with DMF (N, N-dimethylformamide), DMAc
(Dimethylacetamide), butyl cellosolve acetate, N-methyl-2-pyrrolidone, or another solution dissolved in an organic solvent is spin-coated on a substrate, and the solvent is evaporated to form a film. However, the polyimide film thus manufactured has the following problems.

(1) The production method using a polyamic acid as a precursor substance requires a temperature of 250 ° C. to sufficiently perform imidization.
It is necessary to fire at the above high temperature. Also, in the production method using polyimide itself, since there is no suitable low boiling point solvent for dissolving the polyimide, a considerable temperature is required for removing the solvent. For example, organic solvents such as DMF, DMAc, butyl cellosolve acetate, and N-methyl-2-pyrrolidone described above can be used as the solvent for dissolving the polyimide, and all solvents have high boiling points (153 ° C., 165 ° C., and 192 ° C., respectively). , 202 ° C.) and flammable, so that it is necessary to evaporate and dry the solvent at a high temperature while taking into account explosion proof during film formation. From such a thing,
The production of the polyimide film requires a special apparatus for heating, and the production cost is accordingly increased. Further, a circuit such as a TFT may be damaged by the heating.

(2) Since polyimide has insufficient film-forming properties, it is difficult to form a thin and uniform film. For this reason, display unevenness occurs due to uneven film thickness, and a thick film acts as an insulating film. Therefore, it is difficult to realize a liquid crystal display device driven at low voltage.

(3) In addition to the above, the following problem occurs in a rubbing operation for imparting orientation. If the coating has irregularities, the concave portions do not rub, and especially if the panel has a large area, it does not rub uniformly. Therefore, problems such as generation of alignment defects, display unevenness, and display burn-in occur.

[0009] Static electricity is generated on the alignment film, and this static electricity causes a decrease in the function of the TFT.

Further, dust is generated from the rubbing material (such as cotton cloth), and the dust causes display unevenness and changes in the substrate gap.

On the other hand, a non-contact type alignment method has been proposed for the purpose of solving the above-mentioned problems in the rubbing method. For example, in JP-A-5-53118, a layer of a photosensitive composition is formed on a substrate, and a groove having a predetermined pattern is formed in the composition layer by exposure and heat treatment.
There has been proposed a technique for imparting orientation by using the grooves. However, this technique requires a large amount of light energy for forming the groove. Further, since it is difficult to form a uniform groove, problems such as display unevenness occur. Further, the alignment regulating force is not sufficient.

In Japanese Patent Application Laid-Open No. 7-72483,
A technique has been proposed in which a compound layer for forming an alignment film containing polyimide or a polyimide precursor is irradiated with linearly polarized light to polymerize polyimide or the like, thereby imparting orientation. However, since this technique uses polyimide which is an organic polymer, it cannot solve the problem that a thick film thickness causes an increase in liquid crystal driving voltage. There is also a problem that the fixing force of the alignment film to the substrate is not sufficient.

In Japanese Patent Application Laid-Open No. 7-318942, an alignment film having a polymer structure is irradiated with light obliquely to cause a new bond or a decomposition reaction to occur in a molecular chain of the alignment film, thereby giving a molecular structure having an alignment property. Technology has been proposed.
However, this technique also targets an alignment film made of an organic polymer such as polyimide, polyvinyl alcohol, and polystyrene. Therefore, in this technique, the film thickness is large,
The above-mentioned problems, such as a small substrate fixing force, cannot be solved.
In addition, this technology irradiates the alignment film with light obliquely to give a pretilt angle, but requires a highly accurate light irradiator to accurately irradiate light obliquely. Rises.

Further, in addition to the various problems described above, in a liquid crystal display device such as a twisted nematic mode,
There is a problem that the viewing angle is narrow. To cope with this problem, for example, in Japanese Patent Application Laid-Open No. Hei 5-173135, a series of operations of rubbing the alignment film in a certain direction, coating the portion with a resist, and then rubbing in the opposite direction is repeated. A method has been proposed in which the alignment direction of the liquid crystal is made different for each minute region. However, in order to form a plurality of sections having different liquid crystal alignment directions in the rubbing method (contact type), a complicated operation of masking and rubbing each divided section must be repeated. For this reason, according to this technique, the production efficiency of the alignment film is greatly reduced, and troubles due to generation of dust and the like become more serious.

On the other hand, it is also possible to form a plurality of regions having different liquid crystal alignment directions by applying a non-contact type alignment system. However, each of the above techniques (Japanese Patent Laid-Open No. 5-53118)
However, as described above, there are problems such as a large film thickness and insufficient substrate fixing force. Therefore, even if these techniques are used, a liquid crystal alignment film that is sufficiently satisfactory cannot be provided.

Based on the above, the present inventors have previously proposed a technique for manufacturing a novel liquid crystal alignment film having a thickness of nanometer level (Japanese Patent Application Laid-Open No. 3-7913). This technology is
A monomolecular film obtained by chemically adsorbing a silane-based chemically adsorbed substance (also referred to as a surfactant) on a substrate surface is used as an alignment film. According to this technique, an extremely thin film bonded and fixed on a substrate is used. A transparent film can be easily and efficiently formed, and an alignment film having a certain degree of alignment control force on liquid crystal molecules without rubbing can be provided. However, this technique leaves room for improvement with respect to the thermal stability of the orientation and the strength of the orientation regulating force.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems at once, and an object of the present invention is to provide a very thin thin film of nanometer level which can be uniformly and strongly fixed to a substrate. Another object of the present invention is to provide a novel liquid crystal alignment film which has excellent thermal stability of alignment and alignment regulating power, has a wide viewing angle, and can be manufactured with high productivity, and a liquid crystal display device using such a liquid crystal alignment film.

[0018]

In order to achieve the above object, a liquid crystal alignment film of the present invention comprises an adsorbed molecule chemically adsorbed on a substrate surface on which an electrode is formed, directly or through another material layer by a siloxane bond. Wherein the adsorbed molecule is a liquid crystal alignment film comprising a characteristic group represented by the following formula 9 and-
And an O-Si bonding group.

[0019]

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The liquid crystal alignment film having the above structure has one end (-OS).
(i-bonding group side) is composed of a group of adsorbed molecules arranged along the substrate surface with the other end protruding away from the substrate surface while being chemically bonded to the substrate. Then, in the group of adsorbed molecules including the characteristic group represented by Chemical Formula 9 and the —O—Si bonding group,
Since each of the adsorbed molecules is firmly bound to the substrate by a chemical bond, a phenomenon such as peeling of the film does not occur. In this group of adsorbed molecules, liquid crystal molecules can enter gaps (valleys) between the adsorbed molecules. At this time, the tilt (pretilt angle) and orientation direction (pretilt direction) of the liquid crystal molecules with respect to the substrate are determined by the adsorbed molecule. Of the substrate with respect to the substrate and / or the orientation (hereinafter, these are collectively referred to as the orientation).

Therefore, according to the above configuration, a liquid crystal alignment film having a structure in which individual adsorbed molecules can exert an alignment regulating force on the liquid crystal molecules is formed. Such an alignment film has a relationship with the film thickness. Is extremely high in alignment efficiency, and is an extremely thin film, so that it has excellent light transmittance and durability. In addition, since the function as the electric resistance film is small, the electric field for driving the liquid crystal is not hindered. As described above, according to the above configuration, it is possible to increase the display characteristics of the liquid crystal display device, such as the luminance and the contrast ratio, and to realize a liquid crystal alignment film capable of driving the liquid crystal at a low voltage.

In the liquid crystal alignment film having the above structure, -O-Si
Examples of the adsorbed molecule containing the bonding group and the characteristic group represented by Chemical Formula 9 include those having a chemical structure represented by Chemical Formula 10. An adsorbed molecule consisting of the compound of formula 10
Since the molecular length is appropriate, it is convenient for regulating the alignment of the liquid crystal molecules. Further, since the substrate can be firmly bonded to the substrate via Si and the adsorbed molecules can be strongly bonded to each other via Si, an alignment film having excellent durability can be obtained.

[0023]

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Here, it is necessary that the adsorbed molecules have an appropriate molecular length in view of the liquid crystal orientation and cross-linking reactivity, but if n of hydrocarbon (CH ₂ ) n is 1 to 20, This is convenient in terms of liquid crystal alignment and crosslinking reactivity. However, from the viewpoint of crosslinking reactivity, n is preferably 3 to 16, and more preferably, n is 5 to 10. Because, in order for the cross-linking reaction to proceed efficiently, the positional relationship between the carbon-carbon double bond portions of the adsorbed molecules is important, and the light-sensitive portions need to be in contact with or close to each other. When it becomes smaller (for example, when it is less than 5), the rising ratio or the rising angle of the adsorbed molecules with respect to the substrate becomes smaller. That is, since the number of molecules lying on the base material increases, the degree of contact at the carbon-carbon double bond portion (photosensitive portion) decreases, and the crosslinking reaction rate decreases.

On the other hand, when n increases (for example, 10
Is exceeded), the degree of freedom of the molecules in relation to the substrate surface becomes too large, and in this case also, the degree of contact between the adsorbed molecules and the light-sensitive portion is reduced. Therefore, also in this case, the efficiency of the crosslinking reaction is reduced, and as a result, a film having a small crosslinking rate is formed.

The group of adsorbed molecules constituting the liquid crystal alignment film can be oriented in a predetermined direction, and by doing so, a uniform liquid crystal alignment can be obtained.

Further, in the above configuration, the inclination and / or the orientation of the long axis of the adsorbed molecules of the adjacent divided regions with respect to the substrate surface can be different. Here, the above-mentioned divided region refers to a minute region in which one pixel is divided into a plurality and in a pattern, and the orientation direction of the adsorbed molecules is changed in each of the minute regions in which a pixel is divided into a plurality and in a pattern. In the case of a controlled so-called multi-domain type liquid crystal alignment film, transmitted light in each pixel is composed of a plurality of light fluxes having different angles, so that the viewing angle dependency in display is reduced.

Further, in the above structure, the adsorbed molecules of the group of adsorbed molecules are cross-linked via a bond of carbon C ′ and / or carbon C ″ shown in the above chemical formula 9 or chemical formula 10. In an adsorbed molecule assembly in which adsorbed molecules are cross-linked, since the adsorbed molecules are firmly fixed by cross-linking, the tilt or orientation of the adsorbed molecules may be affected by external stimuli such as rubbing or heat. It does not change.
Therefore, a highly reliable liquid crystal alignment film can be obtained.

In the above configuration, the thickness of the liquid crystal alignment film can be set to 0.5 nm or more and less than 10 nm. When the film thickness is in this range, the orientation efficiency in relation to the film thickness is high, and the light transmission and the electric field are not unnecessarily hindered. Therefore, the usefulness as a liquid crystal alignment film is further enhanced.

In the above configuration, the liquid crystal alignment film may be formed of a monomolecular thin film. In the case of a monomolecular layer, each of the adsorbed molecules can directly contribute to the alignment of the liquid crystal molecules, so that the liquid crystal alignment efficiency is significantly improved in relation to the film thickness.

Next, a method for manufacturing the liquid crystal alignment film of the present invention will be described. In the method for producing a liquid crystal alignment film of the present invention, a chemisorption substance having a characteristic group represented by the following formula 11 and a —O—Si bonding group at a molecular terminal portion is dissolved in a nonaqueous solvent to prepare a chemisorption liquid. And a chemical adsorption step in which the chemical adsorption liquid is brought into contact with the substrate surface on which the pixel electrode is formed, and the chemical adsorption substance in the chemical adsorption liquid is siloxane-bonded to the substrate surface.
A step of cleaning the substrate surface to which the chemically adsorbed substance is bound with a non-aqueous solvent for cleaning, followed by draining and drying the cleaning liquid on the substrate in a predetermined direction.

[0032]

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In the above-mentioned production method, after the draining and drying step, the adsorbed molecules on the substrate surface are irradiated with ultraviolet polarized light, and the adsorbed molecules are bonded through the bond of the carbon-carbon double bond in the above formula (11). An ultraviolet polarized light irradiation step of cross-linking each other may be provided.

Further, a series of alignment treatment steps including the liquid drainage drying step and the ultraviolet polarized light irradiation step are repeated a plurality of times by a method of returning to the liquid drainage drying step after the ultraviolet polarized light irradiation step. By changing the draining direction and drying direction, and changing the irradiation area and irradiation direction of UV polarized light, or the irradiation area and irradiation angle, or the irradiation area and irradiation direction and irradiation angle, a plurality of areas corresponding to one pixel can be obtained. In addition, it is possible to adopt a configuration in which the inclination and / or the orientation of the long axis of the adsorbed molecule with respect to the substrate surface is different for each of the divided regions divided in a pattern. According to this configuration, a multi-domain liquid crystal alignment film can be manufactured reliably and with high productivity.

Further, an aprotic solvent may be used as the non-aqueous solvent for washing, and an unreacted chemically adsorbed substance may be washed and removed from the substrate surface to form a monomolecular thin film. .

As a non-aqueous solvent for washing, unreacted chemisorbed substances are washed and removed from the substrate surface using a mixed solution of an aprotic solvent and a protic solvent to form a monomolecular thin film. A configuration can be adopted. Mixing an aprotic solvent and a protic solvent is preferred in that the solubility and the evaporation rate for the chemically adsorbed substance can be adjusted appropriately.

The significance of each configuration described above will be described. When a solution of a chemically adsorbed substance having a characteristic group represented by the above formula (11) and a —O—Si bonding group at a molecular terminal portion is brought into contact with a substrate, the chemically adsorbed substance is bonded to a hydrophilic group on the substrate surface by a siloxane bond (chemical (Also referred to as adsorption) to form a thin film. This thin film is composed of a group of adsorbed molecules in which one end (-O-Si bonding group side) in the major axis direction of the adsorbed molecule is bonded to the substrate surface and the other end is oriented in a direction away from the substrate. When the thin film is composed of a group of molecular assemblies, liquid crystal molecules can enter gaps (valleys) between adsorbed molecules. Then, the inclination and the orientation of the liquid crystal molecules entering the gap with respect to the substrate (these are collectively referred to as the orientation directions) are regulated by the orientation of the adsorbed molecules with respect to the substrate. Therefore, by defining the orientation direction of the adsorbed molecules, the orientation direction of the liquid crystal molecules can be controlled.

On the other hand, the compound having the characteristic group represented by the above formula (11) is transparent in the visible light region and chemically stable, while the carbon-carbon double bond has high sensitivity to ultraviolet light. Having. Therefore, by adsorbing ultraviolet light after chemically adsorbing to the substrate, the adsorbed molecules can be cross-linked via the carbon-carbon double bond portion. At this time, the cross-linking is performed by using ultraviolet polarized light. The direction of coupling can be controlled to a fixed direction corresponding to the polarization direction of the polarized light. Then, the adsorbed molecules on the substrate surface are re-oriented by the irradiation of the polarized light, and since the re-orientation is formed by cross-linking of the molecules, it is hard to change by external stimuli such as heat and rubbing.

Here, as the chemisorbing substance having the characteristic group represented by the above formula (11) and a —O—Si bonding group at a molecular terminal portion, a compound represented by the following formula (12) can be used. When the compound is represented by Chemical formula 12, the compound can be easily chemically adsorbed on the substrate surface, the bond is strong, and the photosensitivity of the carbon-carbon double bond portion is high. Further, a thin film obtained by chemically adsorbing this substance has excellent transparency and durability. In addition, this material has a molecular length that is convenient for aligning liquid crystal molecules. From the above,
In the production method using the compound of (1), a suitable liquid crystal alignment film can be produced with high productivity.

[0040]

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[0041]

The main part of the above manufacturing method will be further described. In the draining and drying step according to the production method of the present invention, first, an excessively unadsorbed chemically adsorbed substance is removed from the substrate surface by a cleaning operation, and the cleaning liquid is dried and removed by draining and drying. Through this series of operations, a monomolecular layer-like thin film in which the adsorbed molecules are oriented in the direction of drainage and drying can be formed. However, the orientation state of the adsorbed molecules due to draining and drying varies due to again draining and drying, and also easily changes due to an external stimulus (for example, heat or rubbing). Therefore, in this specification, this orientation is referred to as temporary orientation.

Here, examples of the draining method include a method of pulling up a substrate immersed in a cleaning liquid at a predetermined angle and a method of applying an air current to the substrate surface from a predetermined direction.

In the step of irradiating the ultraviolet polarized light, the surface of the thin film (adsorbed molecule group) which has been temporarily oriented is irradiated with ultraviolet polarized light. High. Therefore, by irradiation with ultraviolet polarized light, molecules react with each other at the carbon-carbon double bond portion, and the adsorbed molecules are cross-linked to each other via a bond of the carbon in a certain direction corresponding to the polarization direction. Here, the polarization direction may be the same as the above-mentioned temporary alignment direction, or may be a direction different from the temporary alignment direction. It can be oriented. However, the draining direction and the polarization direction do not completely intersect at 90 °, but may be shifted slightly, preferably several degrees or more. This is because if they completely cross each other at 90 °, individual molecules may be oriented in two random directions.

Although the reason has not been sufficiently clarified, when ultraviolet polarized light is irradiated after provisional alignment, cross-linking proceeds smoothly in a certain direction, and the alignment treatment effect by ultraviolet polarized light is enhanced. Has been confirmed experimentally.

In the present specification, the orientation by irradiation with ultraviolet polarized light is referred to as re-orientation in order to distinguish it from the above temporary orientation. Further, the compound molecules chemically adsorbed on the substrate are referred to as adsorbed molecules, and those before adsorption are referred to as chemisorbed substances. Furthermore, it has been experimentally confirmed that the thickness of the thin film obtained by chemically adsorbing the adsorbed molecules on the substrate surface is approximately the molecular length (nanometer level) of the adsorbed molecules.

The difference between the liquid crystal alignment film according to the present invention and the conventional liquid crystal alignment film is as follows. In a conventional liquid crystal alignment film (for example, a polymer film made of the above-mentioned polyamide) in which long main chains are entangled with each other, only the surface portion can contribute to the alignment of the liquid crystal. It is hard to gain strength. Further, in a conventional alignment film which imparts orientation by rubbing, the orientation changes or deteriorates when an external stimulus such as heat or rubbing is applied. Further, since a polymer film such as polyamide is thick and has high electric resistance, it becomes a hindrance factor in light transmission and liquid crystal driving.

On the other hand, even in the case of a liquid crystal alignment film composed of a monomolecular thin film, an alignment film in which adsorbed molecules are not cross-linked has insufficient alignment stability. For example, the chemisorbed substance described in JP-A-3-7913 described above does not have a photoreactive group and thus cannot chemically link the adsorbed molecules.
When heat of about ° C. is applied, the orientation characteristics are apt to deteriorate.

Next, a liquid crystal display device of the present invention using the above liquid crystal alignment film will be described. The liquid crystal display device of the present invention includes a pair of opposed substrates, a liquid crystal alignment film formed on a surface of at least an electrode substrate of the pair of substrates, and a cell gap provided between the opposed pair of substrates. And a liquid crystal accommodated in the liquid crystal display device, wherein the liquid crystal alignment film is a group of adsorbed molecules chemically adsorbed to the substrate surface on which electrodes are formed by siloxane bond directly or through another material layer. Wherein the group of adsorbed molecules includes a —O—Si bonding group and a characteristic group represented by Chemical Formula 13.

[0050]

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In the above configuration, the pretilt angle and / or pretilt direction of the liquid crystal molecules accommodated in the cell gap is controlled by the inclination and / or orientation direction of the major axis of the adsorbed molecules with respect to the substrate surface.

In the liquid crystal display device having the above structure, the inclination and / or the orientation of the major axis of the adsorbed molecule with respect to the substrate surface can be determined by dividing the region corresponding to one pixel into a plurality of divided regions. The configuration may be different for each.

Further, in the in-plane switching type liquid crystal display device in which a pixel electrode and a counter electrode are arranged on the same substrate and a liquid crystal alignment film is formed on a surface of the substrate on which the electrodes are arranged, The alignment film is composed of a group of adsorbed molecules which are chemically adsorbed by a siloxane bond directly or through another material layer to the substrate surface on which the electrodes are formed, and the group of adsorbed molecules is formed by -O-Si bond. And a characteristic group represented by the above formula (13).

In the liquid crystal display device (including the in-plane switching type, the same applies hereinafter), the pretilt angle and / or the pretilt direction of the liquid crystal molecules accommodated in the cell gap is determined by the long axis of the adsorbed molecules. And / or an apparatus controlled by the orientation.

Further, the adsorbed molecules constituting the liquid crystal alignment film may be cross-linked via a bond of carbon C ′ and / or carbon C ″ shown in the above formula (13).

Further, the characteristic group represented by the above formula (13) and -OS
The adsorbed molecule having the i-bonding group may have the structure shown in Chemical formula 14.

[0057]

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The liquid crystal alignment film has a thickness of 0.5 n
m or more and less than 10 nm.

Further, the liquid crystal alignment film can be a monomolecular thin film. When the thin film is a monomolecular thin film, the degree of obstruction of the electric field for driving the liquid crystal is extremely small, and the light transmission is not impeded even if it is arranged in the light transmission path. Therefore, a liquid crystal display device which can be driven at a low voltage and has excellent luminance can be realized.

Incidentally, the ideal monomolecular layer means a layer in which individual constituent molecules are arranged along the substrate surface and there is no overlapping of the molecules. However, it is not practically easy to form a complete monolayer, and the subject of the present invention can be sufficiently achieved without a complete monolayer. Therefore, the monolayer-like thin film referred to in the present invention may be a thin film that can be recognized as a substantially monolayer. For example, there may be a part in which multiple molecules are formed by unadsorbed molecules riding on the adsorbed molecules adsorbed on the substrate, and themselves are not directly bonded and fixed to the substrate but are bonded to directly fixed molecules, Furthermore, a plurality of molecules may be connected in a form in which another molecule is bonded to the molecule that is not directly fixed, and a layer composed of a plurality of molecules may be formed.However, the monomolecular thin film according to the present invention includes: Also included are those that partially include such a layer composed of a plurality of molecules.

Although the above description has been made on the premise that an aggregate of adsorbed molecules is composed of only one kind of chemically adsorbed substance, the adsorbed molecule according to the present invention is mixed with another adsorbed substance. Is also good.

[0062]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described based on examples. (Example 1) First, a method for synthesizing a novel chemisorbed substance used in the present embodiment will be described. (1) Synthesis of a chemisorbed substance: a chalcone skeleton, a carbonyl group bonded to the 4'-position of the benzene ring of the chalcone skeleton, an alkyl group (CH ₂ ) ₆ bonded to the carbonyl group, and -OS bonded to a terminal of the alkyl group.
A chlorosilane-based chemisorbed substance represented by Chemical Formula 15 having an i-bonding group was synthesized according to the following reaction steps 1 to 4.

[0063]

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Reaction step 1: 5L reaction
Hyde 97 g (0.92 mol), 4-Acetylbenzoic acid 150.
0 g (0.92 mol), piperidine 22.5 g, acetic acid 22.5
Then, 2.3 L of toluene and 2.3 L of toluene were charged, and the components were reacted by stirring at 110 ° C. for 5 days.

After cooling the reaction solution to room temperature, the reaction solution was poured into 7.5 L of 1N hydrochloric acid to precipitate crystals. After the crystals were collected by filtration, the crystals were washed successively with water, toluene and chloroform.
Washing with heating was carried out with methanol = 10/1 solution. Thereafter, the crystals were dried to obtain 127.0 g of 4-Carboxychalcone.
Was obtained (yield: 55.1%). This reaction formula is shown in FIG.

Reaction Step 2: 4-Carbox was placed in a 1 L reaction vessel.
80.0 g (0.32 mol) of ychalcone, thionyl chloride 37
7.7 g (3.17 mol) was charged and heated under reflux for 1 hour. Thereafter, thionyl chloride was distilled off, and 87.0 g of 4- (Chlor
ocarbonyl) -chalcone was obtained (101% yield). This reaction formula is shown in FIG.

Reaction step 3: Dry THF (dry tetrahydrofuran) 1.3 in a 5 L reaction vessel under an argon stream.
L, triethylamine 30.0 g (0.30 mol), 1,6-Hexa
70.0 g (0.60 mol) of nediol was charged and cooled to 5 ° C. or less. Then, 4- (Chlorocarbonyl) -chalcone 80.0
g (0.30 mol) in 300 ml of dry THF was added dropwise over 40 minutes while maintaining the temperature of the reaction solution at 5 ° C. or lower.

After stirring at the same temperature for another hour, the reaction mixture was poured into 1.5 L of ice water and adjusted to pH 3 with 1N hydrochloric acid. Next, the product was extracted with ethyl acetate, and the extract was washed with 1N hydrochloric acid and water in that order, and further dehydrated with magnesium sulfate. The thus obtained crude crystals were purified by a silica gel column (mobile phase: n-hexane / ethyl acetate = 2/1), and the crystals purified above were recrystallized from ethyl acetate.

By a series of these processes, 39.4 g of
(6-Hydroxyhexyl) chalcone-4-carboxylate was obtained. The yield was 37.3%. The purity of the product was determined by high performance liquid chromatography and found to be 99%. The reaction equation of this reaction is shown in FIG.

Reaction step 4: (6-Hydroxy
hexyl) chalcone-4-carboxylate 25.0 g (0.071 mol),
100 g (0.59 mol) of silicon tetrachloride was charged into a 300 mL reaction vessel, and stirred at room temperature for 2 hours. Thereafter, excess silicon tetrachloride was distilled off. This resulted in 34.0 g of the final product (98.6% yield). The reaction equation for this reaction is shown in FIG.

Each of the above products was analyzed by measuring its infrared absorption spectrum, MS spectrum and ¹ H NMR spectrum. As a result, the target compound (Chem. 1)
It was confirmed that 4) was obtained. Fig. 2 shows ¹ HNM
3 shows an R spectrum. Each peak in FIG. 2 confirms that the final product is the above-mentioned chemical formula 14.

The above final product is dissolved in chloroform,
Ultraviolet and visible absorption spectra were measured. The result is shown in FIG.
Shown in As shown in FIG. 3, the final product did not have an absorption peak in the visible light region, but had a first absorption peak in the ultraviolet light region at 312 nm and a second absorption peak in 264 nm. From this, it was found that the chlorosilane-based chemisorbed substance was a substance having low sensitivity to visible light and high sensitivity to ultraviolet light.

The ¹ HNMR spectrum analysis was performed using R-1200 manufactured by Hitachi, Ltd., the IR spectrum analysis was performed using FTIR4300 manufactured by Shimadzu Corporation, and the UV / VIS spectrum analysis was performed using UV-240 manufactured by Shimadzu Corporation.

(2) Production of Liquid Crystal Alignment Film A production method of the liquid crystal alignment film will be described with reference to FIGS. The surface of a glass substrate (containing a large number of hydroxyl groups) having a transparent electrode formed on the surface was thoroughly washed and degreased to obtain a glass substrate 1. On the other hand, about 1 part of the silane-based chemically adsorbed substance synthesized above was mixed with a mixed solvent of well-dehydrated siloxane-based solvent (KF96L, manufactured by Shin-Etsu Chemical Co., Ltd.) and chloroform.
Dissolved to a weight percent concentration. This solution was used as a chemical adsorption solution 2.

Then, as shown in FIG. 4, the substrate 1 was placed in the chemical adsorption solution 2 in a dry atmosphere having a relative humidity of 30% or less.
Was immersed for about 1 hour (Step A). Thereafter, as shown in FIG. 5, the substrate 1 was taken in and out of chloroform 3 (aprotic solvent) which had been well dehydrated to wash the substrate surface (step B). Thereafter, the substrate 1 was pulled up in the direction of arrow 4, and was erected vertically in this state in a dry atmosphere to drain and dry the cleaning liquid (Step C). Next, the surface of the substrate 1 was exposed to air containing humidity (50 to 80% relative humidity) (D
Process).

The chemical significance of the above steps is as follows.
The step A of immersing the substrate 1 in the chemical adsorption liquid 2 is a step of dehydrochlorinating the SiCl group of the chlorosilane-based chemical adsorption substance with the hydroxyl group on the substrate surface. By this step, the chlorosilane-based chemically adsorbed substance is firmly bonded to the surface of the substrate 1. Step B, in which the substrate 1 pulled up from the chemical adsorption liquid 2 is washed with chloroform 3, is a step for removing unreacted chemical adsorption substances from the substrate surface. This step is necessary for forming a monomolecular thin film.

Further, the draining and drying step (C
Step) is a step of orienting the adsorbed molecules in a certain direction. When the substrate with the cleaning liquid remaining on the surface of the thin film is set up in a certain direction and the cleaning liquid is drained and dried, the adsorbed molecules are temporarily oriented along the drain drying direction. In addition, when the substrate 1 pulled up after the cleaning in FIG.

Step D of exposing the substrate surface after draining and drying to air containing humidity is a dehydrochlorination reaction step of reacting the remaining Cl of the SiCl group with moisture in the air. This reaction causes the adsorbed molecules to form siloxane bonds.

By the above series of processing steps, a monomolecular film 9 (provisionally oriented state) in which a chlorosilane-based chemically adsorbed substance is siloxane-bonded to hydroxyl groups on the substrate surface was formed. This monomolecular film 9 is a monomolecular thin film composed of the chemical bond units shown in Chemical Formula 16. Instead of immersing the substrate 1 in the chemical adsorption liquid 2, a method of applying the chemical adsorption liquid 2 to the surface of the substrate 1 may be adopted.

[0080]

Embedded image

The thickness of the monomolecular film 9 produced above was measured using an ellipsometer (with a refractive index of 1.45), and was about 2.5 nm.

The orientation state of the monomolecular film 9 was examined using a test cell. The test cell was prepared by fabricating two substrates with the monomolecular film 9, each with the film surface inside, and the liquid draining direction being opposite (antiparallel state).
After overlapping with a gap of μm and sealing the periphery, a nematic liquid crystal (ZL14 manufactured by Merck Ltd.) is filled in the gap.
792). Then, polarizing plates were arranged on both outer surfaces of the cell, and visible light was transmitted from one surface, and the orientation of liquid crystal molecules was examined by a method of observing the transmitted light on the other surface. As a result, it was confirmed that the liquid crystal molecules were oriented along the draining and drying direction.

[Polarized Light Irradiation Step] The polarized light irradiation step will be described with reference to FIG. In FIG. 6, reference numeral 5 denotes the direction of the drain-drying method, 6 denotes ultraviolet polarized light, 7 denotes the polarization direction, 8 denotes a transparent electrode, and 9 denotes a group of adsorbed molecules (monomolecular film). The reorientation treatment for the monomolecular film 9 was performed as shown in FIG. That is, a grantler-type polarizer is set so that the polarization direction 6 of the monomolecular film 9 is oriented substantially in parallel with the draining direction 5, and the UV light 8 of 365 nm from a 500 W high-pressure mercury lamp (2. 1mW / cm2) to 480m
J irradiation was performed.

Next, the chemical properties of the monomolecular film irradiated with the ultraviolet light 8 were measured by FT-IR (Fourier transform in Fourier transform).
frared spectroscopy). As a result, a difference was observed in the IR absorption between the polarization direction and the direction perpendicular thereto, and it was recognized that the IR absorption in the polarization direction was significantly reduced as compared with the direction perpendicular thereto. The decrease in IR absorption is due to the photosensitive group of the chalcone skeleton (carbon-carbon double bond)
Means cross-linking by receiving light energy in the direction of polarization. From this result, it was confirmed that cross-linking was possible by irradiation with ultraviolet polarized light.

Although the direction of bonding between molecules could not be clarified by FT-IR analysis, the cross-linking of the adsorbed molecules does not make the relationship between the adsorbed molecules sterically stable. It is obvious. Therefore, it is considered that the monomolecular film (liquid crystal alignment film) after the realignment treatment is in a more stable alignment state than the temporary alignment state.

Further, a liquid crystal cell was prepared using the substrate with a liquid crystal alignment film after realignment in the same manner as in the above test cell, and a liquid crystal alignment test was performed using this liquid crystal cell. As a result, sufficient light was transmitted through the cell when no voltage was applied, but light transmission was blocked when a voltage of 3 V was applied to the electrode. This means that the homogeneous orientation has been changed to the homeotropic orientation by voltage application.
Further, when the pretilt angle was measured by using an optical crystal rotation method, the crystals were oriented at a pretilt angle of about 2 ° along the polarization direction.

From the above results, when a group of adsorbed molecules having a chemical bond unit represented by the above formula (16) is subjected to a reorientation treatment involving a crosslinking bond in addition to the temporary alignment treatment, the ON and OFF of the voltage are obtained.
It was confirmed that an ultra-thin liquid crystal alignment film capable of realizing a display having a high contrast ratio can be realized by turning it off. In this liquid crystal alignment film, it was confirmed that the adsorbed molecules were cross-linked in a certain direction. Therefore, the alignment characteristics are unlikely to deteriorate. The cross-linking between the adsorbed molecules is performed through a bond of a carbon-carbon double bond of the chalcone skeleton.

Example 2 In Example 2, a liquid crystal alignment film was formed in the same manner as in Example 1 using a substrate on which pixel electrodes were arranged in a matrix, and this substrate with a liquid crystal alignment film was used. Thus, a liquid crystal display device was manufactured. Hereinafter, the manufacturing process of the liquid crystal display device according to the second embodiment will be described with reference to FIG.

On a first substrate 23 having a first transparent electrode group 21 arranged in a matrix and a transistor group 22 for driving this electrode, and a color filter group 2
4 and a second substrate 26 having a second transparent electrode 25 (common electrode) were brought into contact with a chemically adsorbed liquid prepared in the same manner as in Example 1, respectively. A series of processing of cutting and drying and irradiation of polarized light was performed to produce substrates 23 and 26 with a liquid crystal alignment film.

The alignment characteristics of the alignment films of the substrates with liquid crystal alignment films 23 and 26 were examined in the same manner as in Example 1.
The liquid crystal alignment film 27 realigned along the electrode pattern was produced. Therefore, the substrates 23, 2
6, the orientation of the liquid crystal alignment film is set to a 90-degree twist orientation, and the spacer 28 and the adhesive 29 are used for 4.
A 5 micron cell gap was formed and superposed to form a liquid crystal cell.

Next, a TN liquid crystal (ZLI4792; manufactured by Merck) 30 was injected into the cell gap to completely seal the cell. Thereafter, the polarizing plates 31 and 32 were combined to complete a liquid crystal display device.

The pretilt angle of the liquid crystal in the above liquid crystal cell was 5 °. Further, when the device was driven using a video signal while irradiating the backlight 33 from the back of the device, it was confirmed that a clear image could be displayed in the direction of arrow A.

(Example 3) At the time of irradiation with ultraviolet polarized light performed after the temporary alignment, the same pattern is obtained by superposing a pattern-like mask that divides each pixel into four in a checkered pattern on a polarizing plate and performing one exposure. A multi-domain type liquid crystal alignment film in which four divided regions having different alignment directions are formed in a pixel pattern in a pixel is manufactured, and the other conditions are the same as those of the second embodiment. A liquid crystal display device of the type was manufactured.

When this display device was driven by using a video signal in the same manner as in the second embodiment, it was confirmed that an image having a wider viewing angle could be displayed as compared with the second embodiment.

(Embodiment 4) Two comb-shaped electrodes which are engaged with each other in a comb shape without being in contact with each other on the same surface of one substrate, and a reorientation treatment is performed on these electrodes in the same manner as in Embodiment 1. A completed liquid crystal alignment film was formed. Then, an opposing substrate is superimposed on the substrate with a liquid crystal alignment film, and a liquid crystal cell is formed in accordance with a conventional method to perform in-plane switching (IP
An S) type liquid crystal display device was manufactured.

An image display test was also performed on this liquid crystal display device using video signals in the same manner as in Example 2 or 3. As a result, it was confirmed that an image having a wide viewing angle could be displayed.

[Other Matters] (1) In the second and third embodiments, the liquid crystal alignment film is formed on the pair of opposed substrate surfaces, but the liquid crystal alignment film may be formed on only one substrate surface. However, when the liquid crystal alignment film according to the present invention is formed on both of the pair of opposing substrate surfaces, the alignment stability is further improved.

(2) In the above Examples 1 to 4, light of 365 nm from an extra-high pressure mercury lamp was used as ultraviolet polarized light, but the light is not limited to this wavelength. As shown in FIG. 3, the novel chemisorbed substance shown in Chemical formula 15 has a wide absorption range in an ultraviolet light region, so that various kinds of ultraviolet light can be used. For example, 436 nm, 405 nm, 254 nm, KrF
248 nm light obtained by an excimer laser can also be used.

(3) In the third embodiment, one exposure is performed by overlapping a pattern-like mask for dividing each pixel into four in a checkered pattern. A method in which the light step is repeated a plurality of times can be adopted. Specifically, for example, the following can be performed.

The direction of draining and drying in the Nth (where N is an integer of 2 or more) is different from the direction of draining and drying up to the [N-1] th, and the Nth draining and drying performed following the Nth draining and drying is performed. The irradiation area on the substrate in the irradiation of the ultraviolet polarized light is different from the irradiation area up to the [N-1] th irradiation. This makes it possible to make the inclination and / or the orientation of the long axis of the thin film constituent molecules with respect to the substrate surface different for each of the alignment film divided sections obtained by dividing the section corresponding to one pixel into a plurality of patterns. It should be noted that the irradiation can be performed a plurality of times while changing only the irradiation region of the ultraviolet polarized light.However, according to the method of repeating the drainage drying step and the ultraviolet polarized light step, it is easy to control the crosslinking reaction direction. An alignment film having excellent alignment stability can be obtained.

(4) In Examples 1 to 4, chloroform containing no water was used as the cleaning solvent, but the cleaning solvent is not limited to this. In addition, various solvents that do not contain water and dissolve the chemically adsorbed substance can be used.Examples of aprotic solvents include chlorine solvents such as chloroform, benzene, aromatic solvents such as toluene, and the like.
Lactone solvents such as γ-butyl lactone and ester solvents such as ethyl acetate can be used. As the proton solvent, an alcohol solvent such as methanol or ethanol can be used.

(5) In the liquid crystal display device of the present invention, various liquid crystals such as a nematic liquid crystal, a smectic liquid crystal, a discotic liquid crystal, and a ferroelectric liquid crystal can be used.
The liquid crystal alignment film of the present invention, which is composed of a group of adsorbed molecules represented by the formula:
High alignment effect on type liquid crystal. Therefore, in the liquid crystal display device of the present invention, it is preferable to use a TN type liquid crystal,
° It is preferable to form a twist-oriented display device. In addition, as the TN type liquid crystal, for example, biphenyl type, terphenyl type,
Examples thereof include azoxy, Schiff base, phenylcyclohexane, biphenylcyclohexane, ester, pyrimidine, dioxane, bicyclooctane, and cubane.

(6) In the above Examples 1 to 4, the group of adsorbed molecules (thin film) was formed on the surface of the substrate having the electrodes by a method in which the surface of the substrate having the electrodes was brought into direct contact with the chemically adsorbed substance.
A base layer having a hydrophilic group (another substance layer) may be formed on the surface of the substrate having the electrodes in advance, and a chemically adsorbed substance may be chemically bonded to the substrate surface via the base layer. This method is effective when there are few hydrophilic groups on the substrate surface. As the underlayer, OH group, COOH group, NH ₂ group, NH group,
A layer having a hydrophilic group such as an SH group can be used, and more specifically, a SiO ₂ layer or a TiO ₂ layer can be used.

[0104]

As described above, according to the present invention, it is possible to provide a uniform liquid crystal alignment film that is much thinner than conventional organic polymer-based liquid crystal alignment films and has no alignment unevenness. The liquid crystal alignment film has a structure in which the adsorbed molecules are strongly bonded and fixed to the electrode surface by chemisorption, and the adsorbed molecules are cross-linked. The orientation characteristics do not change due to external factors. Moreover, since each of the adsorbed molecules contributes to the control of the alignment of the liquid crystal molecules, remarkably excellent alignment characteristics can be obtained.

Furthermore, a monomolecular layer-like thin film composed of such a group of adsorbed molecules is excellent in transparency to visible light and does not hinder light transmission, and has low electric resistance.
It has a very advantageous property as a liquid crystal alignment film that does not hinder the liquid crystal driving electric field.

Further, according to the production method of the present invention, a multi-domain type liquid crystal alignment film having a different alignment direction for each of the divided sections in a pattern is formed by a relatively simple method of draining and drying and irradiation of polarized light. It can be manufactured reliably and efficiently. When the liquid crystal alignment film according to the present invention is used, a homeotropic alignment mode multi-domain liquid crystal display device having a wide viewing angle, high image quality, high contrast, and excellent high-speed response is almost used. This can be realized without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a chemical reaction formula for explaining a method for synthesizing a novel chemisorbed substance used in the present invention.

FIG. 2 is a ¹ HNMR spectrum chart of a final product synthesized based on the above chemical reaction formula.

FIG. 3 is an ultraviolet-visible absorption spectrum chart of a final product synthesized based on the above chemical reaction formula.

FIG. 4 is a conceptual diagram for explaining a chemical adsorption step.

FIG. 5 is a conceptual diagram for explaining a cleaning step.

FIG. 6 is a conceptual diagram for explaining an ultraviolet polarized light irradiation step.

FIG. 7 is a diagram schematically showing a cross section of the liquid crystal display device of Example 2.

[Explanation of symbols]

1 substrate 2 Chemical adsorption liquid 3 Cleaning liquid 4 Direction of lifting from cleaning solution 5 Drying direction 6. Ultraviolet polarized light 7 Polarization direction 8 Transparent electrode 9 monomolecular film 21 First Transparent Electrode Group 22 TFT group 23 First substrate 24 color filters 25 Second transparent electrode 26 Second substrate 27 Liquid crystal alignment film 28 Spacer 29 adhesive 30 liquid crystal 31, 32 polarizing plate 33 Backlight

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoko Takebe 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-11-167114 (JP, A) International Publication 99/006415 (WO, A1) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/13-1/141

Claims (23)

(57) [Claims] 1. A liquid crystal alignment film comprising a group of adsorbed molecules chemically adsorbed by a siloxane bond directly or through another material layer on a substrate surface on which electrodes are formed, wherein the adsorbed molecules are S and the characteristic group represented by
A liquid crystal alignment film having a -O-Si bonding group having i as a molecular terminal . Embedded image 2. The method according to claim 1, wherein the characteristic group represented by the chemical formula 1 is
2. The liquid crystal alignment film according to claim 1, wherein the adsorbed molecule having a —O—Si bonding group having Si as a molecular terminal is a compound represented by Chemical Formula 2. 3. Embedded image 3. The liquid crystal alignment film according to claim 1, wherein the group of adsorbed molecules forming the liquid crystal alignment film is oriented in a predetermined direction. 4. The group of adsorbed molecules constituting the liquid crystal alignment film has different inclinations and / or orientations of the long axes of the adsorbed molecules of adjacent divided regions with respect to the substrate surface, and the divided region has a plurality of pixels and a pattern. The liquid crystal alignment film according to claim 1, wherein the liquid crystal alignment film is divided into a shape. 5. The adsorbed molecules forming the liquid crystal alignment film are cross-linked via a bond of carbon C ′ and / or carbon C ″ shown in Chemical Formula 1 or Chemical Formula 2. The liquid crystal alignment film according to claim 1. 6. The liquid crystal alignment film according to claim 1, wherein the thickness of the liquid crystal alignment film is not less than 0.5 nm and less than 10 nm. 7. The liquid crystal alignment film according to claim 1, wherein the liquid crystal alignment film is a monomolecular thin film. 8. A compound represented by the following formula 3
Dissolving a chemically adsorbed substance having a -O-Si bonding group having Si as a molecular terminal side in a non-aqueous solvent to prepare a chemically adsorbed liquid; and applying the chemically adsorbed liquid to a substrate surface on which a pixel electrode is formed. A chemical adsorption step in which the chemical adsorption substance in the chemical adsorption liquid is brought into contact with the substrate surface to form a siloxane bond, and the substrate surface to which the chemical adsorption substance is bonded is washed with a non-aqueous solvent for cleaning, and then the cleaning liquid on the substrate is removed. A method for draining and drying the liquid in a certain direction; and a method for producing a liquid crystal alignment film. Embedded image 9. After the draining and drying step, the adsorbed molecules on the substrate surface are irradiated with ultraviolet polarized light to cross-link the adsorbed molecules via the bond of the carbon-carbon double bond portion of Chemical formula 3. The method for producing a liquid crystal alignment film according to claim 8, further comprising an ultraviolet polarized light irradiation step. 10. A method in which a series of alignment treatment steps including the liquid drainage drying step and the ultraviolet polarized light irradiation step are returned to the liquid drainage drying step after the ultraviolet polarized light irradiation step, and the liquid is drained every repetition. By changing the drying direction and changing the irradiation area and irradiation direction of ultraviolet polarized light, or the irradiation area and irradiation angle, or the irradiation area and irradiation direction and irradiation angle, it is possible to repeat one or more times to handle one pixel The method for producing a liquid crystal alignment film according to claim 9, wherein the inclination and / or the orientation of the long axis of the adsorbed molecule with respect to the substrate surface is different for each of the plurality of divided regions divided in a pattern. . 11. A non-aqueous solvent as the non-aqueous solvent for washing, wherein unreacted chemisorbed substances are washed and removed from the substrate surface to form a monomolecular thin film. Item 10. The method for producing a liquid crystal alignment film according to any one of Items 8 to 10. 12. A mixed solution of an aprotic solvent and a protic solvent is used as the nonaqueous solvent for washing, and unreacted chemisorbed substances are washed and removed from the substrate surface to form a monomolecular thin film. The method for producing a liquid crystal alignment film according to claim 8, wherein: 13. A chemisorbed substance having a characteristic group represented by Chemical Formula 3 and a —O—Si bonding group having Si as a molecular terminal side at a molecular terminal portion is a compound represented by Chemical Formula 4. The method for producing a liquid crystal alignment film according to claim 8, wherein: Embedded image 14. A pair of substrates facing each other, a liquid crystal alignment film formed on a surface of at least one of the pair of substrates having electrodes, and accommodated in a cell gap provided between the pair of substrates facing each other. A liquid crystal display device comprising: a group of adsorbed molecules that are chemically adsorbed by a siloxane bond directly or through another material layer to the substrate surface on which the electrodes are formed. The adsorbed molecule is
Si at the molecular end and the characteristic group represented by Chemical Formula 5
A liquid crystal display device having a -O-Si bonding group on the side . Embedded image 15. The adsorbed molecule having a characteristic group represented by Chemical Formula 5 and an —O—Si bonding group having Si as a molecular terminal side at a molecular terminal portion is a compound represented by Chemical Formula 6. The liquid crystal display device according to claim 14. Embedded image 16. The method according to claim 16, wherein a pretilt angle and / or a pretilt direction of the liquid crystal molecules contained in the cell gap is controlled by a tilt and / or an orientation direction of a long axis of the adsorbed molecules with respect to a substrate surface. The liquid crystal display device according to claim 14. 17. The method according to claim 16, wherein the tilt and / or orientation of the major axis of the adsorbed molecule with respect to the substrate surface is different for each of a plurality of adjacent divided regions in which one pixel is divided in a pattern. 3. The liquid crystal display device according to 1. 18. An in-plane switching type liquid crystal display device in which a pixel electrode and a counter electrode are disposed on the same substrate, and a liquid crystal alignment film is formed on a substrate surface on which the electrodes are disposed. The alignment film is composed of a group of adsorbed molecules that are chemically adsorbed by a siloxane bond directly or through another material layer to the substrate surface on which the electrodes are formed, and the adsorbed molecules are
Si at the molecular end and the characteristic group represented by Chemical formula 7
A liquid crystal display device having a -O-Si bonding group on the side . Embedded image 19. The adsorbed molecule having a characteristic group represented by Chemical Formula 7 and an —O—Si bonding group having Si as a molecular terminal side at a molecular terminal portion is a compound represented by Chemical Formula 8. The liquid crystal display device according to claim 18, wherein: Embedded image 20. A pretilt angle and / or a pretilt orientation of liquid crystal molecules accommodated in the cell gap is controlled by an inclination and / or an orientation direction of a major axis of the adsorbed molecule with respect to a substrate surface. The liquid crystal display device according to claim 18. 21. The adsorbed molecules constituting the liquid crystal alignment film are cross-linked via a bond of carbon C ′ and / or carbon C ″ shown in Chemical Formula 5, 6, 7, or 8. The liquid crystal display device according to any one of claims 14 to 20, wherein: 22. The liquid crystal alignment film has a thickness of 0.5 nm.
22. The liquid crystal display device according to claim 21, wherein the thickness is less than 10 nm. 23. The liquid crystal display device according to claim 21, wherein the liquid crystal alignment film is a monomolecular thin film.