JP3400358B2 - Liquid crystal alignment film, method of manufacturing the same, liquid crystal display device using the same, and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment film, a method for manufacturing the same, a liquid crystal display device using the same, and a method for manufacturing the same. More specifically, the present invention relates to a liquid crystal alignment film used for a flat display panel using a liquid crystal for displaying a television (TV) image, a computer image, etc., a manufacturing method thereof, a liquid crystal display device using the same, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, a color liquid crystal display element has a pair of substrates each having a transparent electrode arranged in a matrix and a liquid crystal alignment film formed on the transparent electrode, and a liquid crystal alignment film surface facing inside. It has a structure in which liquid crystal is sealed in the gap with the gap facing each other.

Specifically, for example, a first glass substrate on which a pixel electrode and a thin film transistor (TFT) array are formed, and a plurality of red, blue and green color filters are formed.
Further, a polymer film is formed on each surface of the second glass substrate on which the common transparent electrode is formed, and the film surface is rubbed to impart liquid crystal orientation. Then
The coated surface (liquid crystal alignment film surface) is faced to the inside with a spacer interposed, and the substrates are opposed to each other, and the peripheral edges of the substrates are bonded to form an empty cell (panel structure). Liquid crystal such as twisted nematic (TN) is injected into the empty cell and hermetically sealed to form a liquid crystal display element.

Further, the liquid crystal display device as an optical display device is constructed by disposing the deflection plates on both outer surfaces of the liquid crystal display element and disposing the backlight on the outside of the first electrode.

The liquid crystal display device having this structure is intended to display an arbitrary image by controlling the light transmission by changing the alignment state of the liquid crystal by turning ON / OFF the voltage between electrodes by the TFT. The alignment film that controls the alignment state of the liquid crystal when no voltage is applied plays an extremely important role in controlling display performance.

By the way, conventionally, as a liquid crystal alignment film,
Polyimide films have been widely used from the past because of their excellent affinity with liquid crystals, heat resistance, and substrate adhesion. Then, as its manufacturing method, a solution of a polyamic acid that is a precursor polymer of polyimide dissolved in an organic solvent such as xylene is spin-coated on a substrate, and then baked to imidize the polyamic acid to form a polyimide film. Method and
A solution of polyimide itself dissolved in an organic solvent such as DMF (N, N-dimethylformamide), DMAc (dimethylacetamide), butyl cellosolve acetate, and N-methyl-2-pyrrolidone is spin-coated on a substrate, and then the solvent is evaporated. The method of forming a coating is used. However, the polyimide film has the following problems and is not sufficiently satisfactory as a liquid crystal alignment film. That is,

(1) The production method using a precursor substance, polyamic acid, is carried out at 250 ° C. for sufficient imidization.
It is necessary to bake at the above high temperature. Even in the production method using the polyimide itself, there is no suitable low-boiling point solvent for dissolving the polyimide, so that a considerable temperature is required for removing the solvent. Specifically, 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, but both solvents have high boiling points (153 ° C. and 165 ° C., respectively). , 192 ° C, 202
Since it is flammable, it is necessary to evaporate and dry the solvent at a high temperature while taking explosion protection into consideration during film formation. For this reason, a special apparatus for heating is required to manufacture the polyimide film, and the manufacturing cost increases accordingly. Further, there is a possibility that the circuits such as the TFT may be damaged by heating.

(2) Further, since the film forming property of polyimide is not sufficient, it is difficult to form a thin film having a uniform film thickness. For this reason, display unevenness is caused due to non-uniformity of the film thickness, and the thick coating film acts as an insulating film, which makes it difficult to realize a low-voltage driven liquid crystal display element.

(3) In addition to the above, the following problems occur in the rubbing operation for imparting orientation. When the coating film has irregularities, the concave portions do not rub, and particularly when the panel has a large area, it does not rub evenly.
Problems such as uneven display and image sticking occur. In addition, static electricity is generated on the alignment film, which causes the function of the TFT to deteriorate. Further, dust is generated from the rubbing material (cotton cloth or the like), and this dust causes display unevenness or changes in the substrate gap.

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

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

Further, in Japanese Patent Application Laid-Open No. 7-318942, an alignment film having a polymer structure is obliquely irradiated with light to cause a new bond or a decomposition reaction in a molecular chain of the alignment film to have 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, or polystyrene. Therefore, this technique has a large film thickness,
The above-mentioned problems such as a small substrate fixing force cannot be solved.
In addition, this technique requires that the alignment film be obliquely irradiated with light in order to provide a pretilt angle, but a highly accurate light irradiation device is required for accurate oblique irradiation. The production cost increases accordingly.

On the other hand, in a liquid crystal display device of twisted nematic mode or the like, it has been a problem that the viewing angle is narrower than before, and as a method for solving this problem, for example, in Japanese Patent Laid-Open No. 5-173135. , A method of forming a plurality of regions with different alignment directions of liquid crystal by repeating a method of rubbing the alignment film in a certain direction, further coating the portion with a resist, and then rubbing in the opposite direction is proposed. There is. However, in order to form a plurality of sections having different liquid crystal alignment directions by the rubbing method (contact type) method, it is necessary to repeat the complicated work of masking each divided section and rubbing. Therefore, according to this technique, the production efficiency of the alignment film is significantly reduced, and the problem of dust generation is a serious problem.

On the other hand, it is also possible to form a plurality of regions in which the alignment directions of the liquid crystal are different by applying the above-mentioned respective techniques of Japanese Patent Laid-Open No. 53118/1993. However, since each of the above techniques has problems such as a large film thickness and insufficient substrate fixing force as described above, it is still impossible to provide a sufficiently satisfactory liquid crystal alignment film even by using these techniques.

By the way, the inventors of the present invention disclosed in Japanese Patent Laid-Open No. 3-79.
In Japanese Patent Laid-Open No. 13 (1994), a technique capable of producing an alignment film having a film thickness of nanometer level with high productivity is proposed. This technology
A monomolecular film obtained by chemically adsorbing a silane-based surfactant on the surface of a substrate is used as an alignment film. According to this technology, it is possible to easily and efficiently form an extremely thin transparent film bonded and fixed on a substrate, and to provide an alignment film having a certain degree of alignment control force on liquid crystal molecules without rubbing. it can. However, this technique still has room for improvement in terms of thermal stability of orientation and strength of orientation regulating force.

[0016]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems all at once, and an object of the present invention is to form 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 is excellent in thermal stability of alignment and alignment regulating force, 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.

[0017]

In order to achieve the above object, the liquid crystal alignment film of the present invention is a monomolecular film-like film formed on the surface of a substrate, wherein the substance forming the monomolecular film is It is characterized in that it is bonded and fixed to the surface of the substrate directly or through another coating, and is cross-linked in the state of being oriented in a predetermined direction.

In the liquid crystal alignment film of the present invention, the precursor substance (chemisorption substance) forming the monomolecular film is represented by the following formula (Chemical Formula 6) (wherein R 1 and R 2 are each hydrogen or an alkyl group having 1 to 3 carbon atoms). A group or a group represented by an alkoxy group having 1 to 3 carbon atoms) and Si, and the precursor is crosslinked at the carbon-carbon double bond portion of the group represented by the above (Chemical Formula 6). A monomolecular film having orientation is formed.

[0019]

[Chemical 6]

Here, the precursor of the liquid crystal alignment film of the present invention is
A certain chemisorbed substance contains a group represented by the above chemical formula 6.
The number of carbon atoms in the chemical formula 6 is 1 to 3
The alkyl group of is —CH₃, -C₂H_Five, -C₃
H₇Examples of the group include alkoxy having 1 to 3 carbon atoms.
As the group, -OCH₃, -OC₂H_Five, -OC₃H ₇
A group can be mentioned.

In the liquid crystal alignment film of the present invention, the substance constituting the monomolecular film is represented by the following formula (Formula 7).
(However, n represents an integer of 1 to 14), the following formula (Formula 8), (where n is an integer of 1 to 14 and R is a carbon number 1).
To 14 alkyl groups or phenyl groups), the following formula (Formula 9) (wherein n represents an integer of 1 to 14 and R represents an alkyl group of 1 to 14 carbon atoms or a phenyl group),
And a chemical bond unit represented by the following formula (Chemical Formula 10) (wherein n represents an integer of 1 to 14 and R represents an alkyl group having 1 to 14 carbon atoms or a phenyl group). It is preferable. The inclusion of these chemical bond units is convenient because the monomolecular film has a large orientation effect on the liquid crystal.

[0022]

[Chemical 7]

[0023]

[Chemical 8]

[0024]

[Chemical 9]

[0025]

[Chemical 10]

As a manufacturing method, a chemical adsorption liquid prepared from a first silane-based chemical adsorption substance having a group represented by the above (Chemical formula 1) and Si and a non-aqueous solvent is brought into contact with a substrate, and the chemical The first step of forming a monomolecular film-like film that is bonded and fixed to the substrate surface by chemically adsorbing one end of the constituent molecules of the adsorbed substance to the substrate surface, and irradiating the substrate surface with ultraviolet rays or far ultraviolet rays. Thus, the production method can be adopted, which includes a second step of cross-linking the adsorbed molecules with each other through a bond of the vinyl group portion of the group represented by the above (Chemical formula 1).

In this case, after the first step, a step of washing with an organic solvent is performed, and a substrate is erected in a desired direction to drain the liquid, and molecules bound to and fixed to the substrate are primarily removed in the liquid draining direction. A liquid crystal alignment film in the form of a monomolecular film, which has a more stable alignment action when the group represented by (Chemical Formula 6) is cross-linked along a specific direction in the second process. Can be provided.

When irradiation with ultraviolet rays or deep ultraviolet rays is carried out through a polarizing plate or a transparent plate having a large number of groove scratches of about 0.1 to 0.3 μm on the surface, it is irradiated along the polarization direction or the rubbing direction. The substances constituting the molecular film can be crosslinked.

Furthermore, at the time of irradiation with ultraviolet rays or deep ultraviolet rays,
By performing a step of exposing a patterned mask on a polarizing plate or a transparent plate whose surface has been rubbed, and performing the exposure once or more, in the alignment film in the same plane, a portion where the patterned alignment direction is different for each pixel Can be provided at a plurality of locations. Further, when this method is used, a multi-domain type liquid crystal alignment film in which the alignment direction is made different for each small section into which one pixel is divided can be manufactured with high productivity.

In the first step, the first
And a second silane-based chemical adsorbent having a molecular length different from that of the first silane-based chemical adsorbent are mixed at a predetermined ratio to prepare the chemisorbed liquid, and a single molecule is prepared. It is convenient to form a film because the degree of photopolymerization of the first silane-based chemical adsorbent can be controlled.

Furthermore, when the second silane-based chemical adsorbent has a shorter molecular length than the first silane-based chemical adsorbent, the density of the polymerizable groups can be controlled and the degree of photopolymerization can be controlled. It is more convenient to control.

On the other hand, the first substrate having the first electrode group placed in advance in a matrix form is directly or after forming an arbitrary thin film, and then the above-mentioned carbon chain is contained at the terminal or part of the carbon chain. The chemical adsorption substance molecule in the chemical adsorption liquid and the substrate surface are brought into contact with the chemical adsorption liquid prepared by using the first silane-based chemical adsorption substance containing the group represented by (Chemical Formula 6) and Si. In the first step of chemically reacting and chemically fixing the chemically adsorbed substance molecules on the surface of the substrate at one end, and after washing with an organic solvent, the substrate is further erected in a desired direction and drained, A second step of pre-orienting the fixed molecule; a third step of irradiating with ultraviolet rays or deep ultraviolet rays to polymerize and crosslink the group represented by the above (Chemical Formula 6) along a specific direction; A first substrate having a first electrode group and a second substrate Substrate, or the second electrode or the second substrate having an electrode group, and the fourth step of the electrode surface inside bonded and fixed in alignment while maintaining a predetermined gap,
A fifth aspect of injecting a predetermined liquid crystal between the first and second substrates
A liquid crystal display device in which liquid crystal is sandwiched between two electrodes facing each other, wherein the liquid crystal alignment film has a monomolecular film shape, and a substance forming the film has a predetermined thickness. Liquid crystal is polymerized along the direction and is directly or indirectly formed on the electrode-side surface of at least one of the substrates on which two opposing electrodes are formed so that liquid crystals are formed on the two opposing electrodes. A liquid crystal display device can be provided by a manufacturing method characterized in that the liquid crystal display device is sandwiched by the above-mentioned alignment film.

At this time, the substance forming the liquid crystal alignment film contains the group represented by the above (Chemical formula 6) and Si, and is a carbon-carbon double bond portion of the group represented by the above (Chemical formula 6). When cross-linked, it has a great effect of orienting the twisted nematic (TN) type liquid crystal.

Further, when the above-mentioned coating is formed as a liquid crystal alignment film on each of the surfaces of the substrate on which two electrodes facing each other are formed, a liquid crystal display device further excellent in alignment stability can be obtained. However, the coating film may be formed as a liquid crystal alignment film on the surface of only one of the substrates.

Further, in the third step of irradiating with ultraviolet rays or far ultraviolet rays, a step of exposing a polarizing plate with a patterned mask is performed, and the patterned alignment is performed for each pixel in the alignment film in the same plane. By providing a plurality of portions having different directions, it is possible to provide a liquid crystal display device having a wide display visual field characteristic. In addition, this method uses in-plane switching (IP) in which opposing electrodes are formed on the surface of one substrate.
Even for the S) type liquid crystal display device, it is extremely effective because rubbing is unnecessary.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a substrate is brought into contact with a chemical adsorption liquid prepared from a first silane-based chemical adsorption substance having a group represented by the above (Chemical Formula 6) and Si and a non-aqueous solvent. And chemically reacting the molecule of the chemical adsorbent with the surface of the substrate to bond and fix the molecule of the chemical adsorbent to the surface of the substrate at one end to form a monomolecular film; and the surface of the substrate. By irradiating the group represented by the above-mentioned (Chemical Formula 6) by irradiating the group with UV rays or deep UV rays.
Which is a monomolecular film formed on the surface of the substrate by using the manufacturing method including the step of, and the substance constituting the monomolecular film is oriented in a predetermined direction on the surface of the substrate. A novel liquid crystal alignment film, which is characterized by being polymerized in a state, has a liquid crystal alignment regulating force in a predetermined direction.

Further, after forming an arbitrary thin film directly on the first substrate having the first electrode group mounted on the matrix or on the surface of the substrate, the carbon chain is contained and the end or part of the carbon chain is contained. Is brought into contact with a chemical adsorbent prepared by using a first silane-based chemical adsorbent having a group represented by (Chemical Formula 1) and Si, and the chemical adsorbent and the substrate surface are chemically reacted, A first step of binding and fixing the adsorbent substance to the substrate surface, and a step of washing the substrate surface with an organic solvent, standing the substrate in a desired direction and draining it, and pre-orienting the immobilized molecules in the draining direction. The second step is to irradiate ultraviolet rays or far ultraviolet rays to cross-link the adsorbed molecules along a specific direction through the bonds of the carbon-carbon double bond portion of the group represented by the following (Chemical formula 1). 3 step, the first substrate, and the counter electrode A fourth step of aligning and adhering the sometimes-occurring second substrate with the electrode surface inside and maintaining a predetermined gap, and injecting a predetermined liquid crystal between the first and second substrates. And a fifth step for providing a liquid crystal display element having excellent display performance with high productivity.

[0038]

EXAMPLES The present invention will be described in more detail below with reference to examples. (Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

A glass substrate 1 having a transparent electrode formed on its surface
Prepare (containing a large number of hydroxyl groups on the surface) and wash and degrease well in advance. Next, the above substrate is used as a chlorosilane-based chemisorption material containing a carbon chain and containing the group represented by the above (Chemical formula 6) and Si at the terminal or part of the carbon chain, and the following chemical formula (Chemical formula 11) This material, as shown in Figure 1,
There is a photosensitivity peak at 240 to 370 nm. The compound represented by (4) was dissolved in a non-aqueous solvent at a concentration of about 1% by weight to prepare a chemisorption solution.

[0040]

[Chemical 11]

In this example, well-dehydrated hexadecane was used as the non-aqueous solvent. The solution thus prepared was used as the adsorption solution 2, and the substrate 1 was immersed (applied) in the adsorption solution 2 for about 1 hour in a dry atmosphere (relative humidity of 30% or less) ( (Fig. 2). Then, after pulling up from the liquid and washing with well-dehydrated n-hexane 3 as a non-aqueous solvent containing no water, the substrate is pulled up from the washing liquid while standing in a desired direction to drain the washing liquid to remove water. It was exposed to air containing (Fig. 3). In the series of steps described above, a dehydrochlorination reaction occurs between the silicon chloride group of the chlorosilane-based chemical adsorbent and the hydroxyl group on the surface of the substrate to form a bond represented by the following formula (Formula 12). The bond represented by the following formula (Formula 13) was formed by reacting with the water content.

[0042]

[Chemical 12]

[0043]

[Chemical 13]

At this time, when the substrate is further washed with a non-aqueous organic solvent such as n-hexane or chloroform, the substrate is erected in a desired direction to drain the liquid, the fixed molecules are primarily removed in the liquid draining direction. It can be oriented.

By the above treatment, the chemisorption monomolecular film 4 formed by the reaction of the chemisorption substance with the substrate is chemically bonded to the portion of the substrate surface containing the hydroxyl group through the covalent bond of siloxane. And the bound molecules are oriented to a direction opposite to the liquid draining and pulling direction 5 to some extent, and about 2
It was formed with a film thickness of nm (FIG. 4).

Thereafter, two kinds of substrates in this state are used, and the polarization direction 6 is set in a direction substantially parallel to the liquid draining and pulling direction 5.
A polarizing plate (HNP'B) 7 (manufactured by Polaroid Co., Ltd.) is placed on the substrate so that the light is oriented, and ultraviolet light 8 of 365 nm (i line) of a 500 W ultra-high pressure mercury lamp (2.6 after passing through the polarizing film is used).
mW / cm @ 2) was used to irradiate 100 mJ (FIG. 5, 9 in the figure represents a transparent electrode).

Then, when the anisotropy of the adsorbed molecule was examined by FTIR, it was found that the photosensitive group was photopolymerized and the absorption of vinyl group was lost. That is, the following formula (Formula 1
The bond of 4) was generated.

[0048]

[Chemical 14]

Although the binding direction was not clear, the absorption was clearly different between the polarization direction and the vertical direction. This indicates that the substance forming the monolayer is bonded and fixed on the surface of the substrate and photopolymerized along the predetermined direction at the photosensitive group portion as shown in FIG. There is.

Therefore, two substrates in this state are used and combined so that the chemisorption films face each other, and set so that the polarization directions are parallel and the draining directions are opposite, that is, antiparallel. Assembled a micron gap liquid crystal cell, and made a nematic liquid crystal (ZLI4
792; manufactured by Merck & Co., Inc.) was injected to confirm the alignment state, and the injected liquid crystal molecules were aligned with the substrate at a pretilt angle of 2.5 ° along a direction intersecting with the polarization direction by 90 °.

At this time, in order to align the alignment direction of the adsorbed molecules in the irradiation part in one direction, the washing liquid cutting and pulling direction 5 and the polarization direction do not completely intersect each other at 90 °.
It is necessary to shift a little, preferably several degrees or more. In this case, the polarization direction 6 may be aligned so as to be parallel to the cleaning liquid draining direction at the maximum. If they intersect at 90 ° completely, the individual molecules may face in two directions.

Here, when it is desired to selectively change the orientation direction, a patterned mask is overlaid on the polarizing plate at the time of exposure.
When an ultraviolet ray having a wavelength of 365 nm is irradiated with an energy of 0 to 200 mJ, the orientation direction changes only in the irradiated portion, and the portion having different orientation directions in a pattern in the orientation film in the same plane, that is, the cleaning liquid cutting-up direction 5 It was possible to provide a plurality of portions where the liquid crystal is aligned along the polarization directions 6 and 6, respectively. Furthermore, when a desired mask was placed on a polarizing plate and exposed to light under the same conditions a plurality of times, a plurality of monomolecular liquid crystal alignment films having different alignment directions could be produced very easily in a pattern. That is, it was possible to provide a liquid crystal display device in which one picture element was multi-domain aligned.

In this example, a hydrocarbon-based n-hexane containing an alkyl group was used as a water-free solvent for washing, but other than this, water is not contained and the chemisorbed substance is dissolved. Any solvent can be used as long as it is a solvent. For example, other than this, a solvent containing a fluorocarbon group, a carbon chloride group, or a siloxane group, such as Freon 113, chloroform, or hexamethyldisiloxane can be used.

Further, as in this embodiment, the following formula (Formula 1)
The liquid crystal alignment film containing the chemical bond unit represented by 5) has a particularly high alignment effect on the twisted nematic liquid crystal, but other than that, as a substance capable of forming a film similarly, the following formula (Formula 16) is used. The indicated substances were applicable as well.

[0055]

[Chemical 15]

[0056]

[Chemical 16]

(In the formula, n represents an integer of 1 to 14) At this time, as the non-aqueous organic solvent for preparing the chemical adsorption liquid, an alkyl group, a fluorocarbon group, a carbon chloride group or a siloxane group is used. A solvent containing was available.

(Example 2) Under the conditions described in Example 1, instead of the substance used in the example, a chemical adsorption substance containing the photosensitive group represented by the above (Chemical Formula 6) and Si was used. Using the substance represented by the following formula (Chemical Formula 17) (this substance has a photosensitivity peak at 240 to 290 nm as shown in FIG. 7) and rubbing with an abrasive grain of 0.3 μm,
Acrylic plate with a large number of 0.1-0.3 μm groove scratches was placed on the substrate and set,
Far-ultraviolet light of 54 nm (2.1 mW / c after transmitting acrylic plate
The same experiment was carried out except that 80 mJ was irradiated using m2).

[0059]

[Chemical 17]

Further, using two substrates in this state, the chemisorption films were assembled so as to face each other and set so as to be anti-parallel, and a 20 micron gearup liquid crystal cell was assembled, and a nematic liquid crystal (ZLI4792; manufactured by Merck Ltd.) was assembled. ) Was injected to confirm the alignment state, the injected liquid crystal molecules were aligned at a pretilt angle of 4 ° with respect to the substrate along a direction intersecting the polarization direction by 90 °.

As a substance capable of forming a film in the same manner as the above substance, a substance represented by the following formula (Formula 18),

[0062]

[Chemical 18]

(In the formula, n represents an integer of 1 to 14, R represents an alkyl group having 1 to 14 carbon atoms, or a phenyl group. However, the total number of carbon atoms of n and R is 1 to 26) or , A substance represented by the following formula (Formula 19),

[0064]

[Chemical 19]

(In the formula, n represents an integer of 1 to 14, R represents an alkyl group having 1 to 14 carbon atoms, or a phenyl group. However, the total number of carbon atoms of n and R is 1 to 26) or A substance represented by the following formula (Formula 20) can be used.

[0066]

[Chemical 20]

(In the formula, n represents an integer of 1 to 14, R represents an alkyl group having 1 to 14 carbon atoms, or a phenyl group. However, the total number of carbon atoms of n and R is 1 to 26.) Specifically, the following formulas (formula 21), (formula 22),
The substances represented by (Chemical formula 23), (Chemical formula 24) and (Chemical formula 25) were applicable in the same manner although the exposure dose was different.

[0068]

[Chemical 21]

(This substance has a photosensitivity peak at 240 to 280 nm.)

[0070]

[Chemical formula 22]

(This substance has a photosensitivity peak at 240 to 290 nm.)

[0072]

[Chemical formula 23]

(This substance has a photosensitivity peak at 240 to 310 nm.)

[0074]

[Chemical formula 24]

(This substance has a photosensitivity peak at 240 to 330 nm.)

[0076]

[Chemical 25]

(This substance has a photosensitivity peak at 240 to 330 nm.) (Example 3) Under the conditions described in Example 1, as a chlorosilane-based chemical adsorbent, A similar experiment was conducted except that the substance represented by the formula (Formula 26) was mixed at an equimolar ratio, and the chemisorption solution was prepared by dissolving the substance in a non-aqueous solvent at a concentration of about 1% by weight.

[0078]

[Chemical formula 26]

As a result, a dehydrochlorination reaction occurs between the silicon chloride groups of the two types of chlorosilane-based chemical adsorbents and the hydroxyl groups on the surface of the substrate, and further reacts with moisture in the air, thereby Chemical formula 13) and the following (chemical formula 2)
A monomolecular film 10 containing the bond of 7) at a ratio of about 1: 1 was formed.

[0080]

[Chemical 27]

Thereafter, two kinds of substrates in this state were used, and a polarizing plate (HNP'B) (manufactured by Polaroid Co., Ltd.) was set on the substrates so that the polarization direction was oriented substantially parallel to the liquid draining and pulling direction, 365 of the super high pressure mercury lamp of 500W
nm (i-line) ultraviolet light (2.6 mW / cm after passing through the polarizing film)
2) was used to irradiate 70 mJ.

Then, when the anisotropy of the adsorbed molecule was examined by FTIR, it was found that the photosensitive group was photopolymerized and absorption of the vinyl group was lost as in Example 1. Although the binding direction was not clear, the absorption was clearly different between the polarization direction and the perpendicular direction. This means that the substance constituting the monomolecular film is bonded and fixed to the surface of the substrate, and the monomolecular film 10 'photopolymerized at the photosensitive group portion along a predetermined direction as shown in FIG. It has been formed.

Next, two substrates in this state are used and combined so that the chemical adsorption films face each other, and set so that the polarization directions are parallel and the liquid draining directions are opposite, that is, antiparallel. After assembling a micron gap liquid crystal cell and injecting nematic liquid crystal (ZLI4792; manufactured by Merck) to confirm the alignment state, the injected liquid crystal molecules have a pretilt angle of about 90 ° with the substrate along the direction intersecting 90 ° with the polarization direction. It was oriented at 1.5 °.
This indicates that the photopolymerized molecules are more tilted than in Example 1. Note that this film had a larger orientation regulating force than the film obtained in Example 1.

(Embodiment 4) Next, a manufacturing process in the case of actually manufacturing a liquid crystal display device using the liquid crystal alignment film will be described with reference to FIG.

First, as shown in FIG. 9, on a first substrate 13 having a first electrode group 11 mounted in a matrix and a transistor group 12 driving the electrodes, and a first electrode group. According to the same procedure as in Example 1, the prepared chemical adsorption liquid was applied onto the second substrate 16 having the color filter group 14 and the second electrode 15 placed so as to face each other, and the same chemical adsorption unit was applied. A molecular film was prepared.

As a result, the liquid crystal alignment film 27 realigned along the electrode pattern as in Example 1 could be produced. Next, the first and second substrates 13 and 16 were aligned so that the electrodes face each other, and a spacer 18 and an adhesive 19 were used to form a cell in which the light distribution direction was twisted by 90 degrees with a gap of about 5 microns. . After that, the TN liquid crystal (ZLI4792; manufactured by Merck & Co., Inc.) 20 was injected into the first and second substrates, and then polarizing plates 21 and 22 were combined to complete a display element. The pretilt angle of the liquid crystal injected at this time was 2.3 °.

Such a device was able to display an image in the direction of arrow A by driving each transistor using a video signal while illuminating the entire surface with the backlight 23. (Example 5) After forming the monomolecular film in Example 3, each pixel was formed in a checkered pattern on the polarizing plate under the same conditions as in Example 1.
1 step of overlapping and exposing the pattern mask to be divided
When it was repeated, four portions having different alignment directions could be provided in a pattern in the same pixel. Then, by using the substrate on which this alignment film is formed, it is possible to obtain the right and left 60
The viewing angle of the liquid crystal display device, which was 20 ° above, 20 ° above and 50 ° below, was significantly improved to 60 ° left and right and 50 ° up and down.

By forming the above-mentioned coating as an alignment film on each of the surfaces of the substrates on which two electrodes opposed to each other were formed, a liquid crystal display device having further excellent alignment stability was obtained. In addition, opposing electrodes are formed on the surface of one of the substrates, that is, in-plane switching (IP
Even for the S) type liquid crystal display device, it was extremely effective because rubbing was unnecessary.

Further, in the above-mentioned Examples 1 and 2, the ultraviolet rays (i-line of the ultra-high pressure mercury lamp) were used as the light used for the exposure, respectively.
The light having a wavelength of 365 nm and the light having a wavelength of 254 nm, which is deep ultraviolet light, are used.
It is also possible to use far-ultraviolet light of 248 nm obtained with a 36 nm and 405 nm or a KrF excimer laser. In particular, light of 248 nm and 254 nm is easily absorbed by most substances, so that energy alignment efficiency is high.

As the chemical adsorbent, a substance containing an alkoxysilyl group or an isocyanate silyl group could be used instead of the substance containing a silicon chloride group such as the chlorosilane-based chemical adsorbent used in this example. Again, highly oriented films were obtained.

[0091]

As described above, the liquid crystal alignment film of the present invention is remarkably uniform and thin as compared with the conventional one, and the alignment direction of the injected liquid crystal is controlled by far ultraviolet rays or photopolymerization irradiation using ultraviolet rays. The pretilt angle is a novel and highly thermal stable alignment film in which the composition of the photopolymerized monomolecular film is controlled. According to the manufacturing method of the present invention, the liquid crystal alignment film can be provided. effective.

Further, after the monomolecular film forming step, if the step of exposing the polarizing plate with a patterned mask is repeated a plurality of times, a plurality of portions of the oriented film in the same plane which are different only in the oriented direction of the patterned shape are formed. A multi-domain liquid crystal display device, in which the orientation of each pixel is divided into a plurality of types, which has been difficult with conventional rubbing, can be efficiently and rationally produced.

Furthermore, since such an alignment film is firmly bonded to the surface of the substrate through a covalent bond, it is possible to provide an extremely highly reliable liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a diagram showing an ultraviolet absorption spectrum of a chlorosilane-based chemical adsorbent (Chemical Formula 11) used in Example 1 of the present invention.

FIG. 2 is a conceptual sectional view for explaining a chemical adsorption step used for producing a monomolecular liquid crystal alignment film in Example 1 of the present invention.

FIG. 3 is a conceptual cross-sectional view for explaining a cleaning step for producing a monomolecular liquid crystal alignment film in Example 1 of the present invention.

FIG. 4 is a conceptual diagram in which a cross section is enlarged to a molecular level in order to explain an alignment state of molecules in a monomolecular liquid crystal alignment film after solvent washing in Example 1 of the present invention.

FIG. 5 is a conceptual diagram of an exposure process used to re-orientate and polymerize molecules adsorbed by polarized light exposure in Example 1 of the present invention.

FIG. 6 is a conceptual diagram enlarged to a molecular level in order to explain a polymerization state of molecules in a monomolecular liquid crystal alignment film after polarized light exposure in Example 1 of the present invention.

FIG. 7 is a diagram showing an ultraviolet absorption spectrum of a chlorosilane-based chemical adsorbent (Chemical Formula 17) used in Example 2 of the present invention.

FIG. 8 is a conceptual diagram enlarged to a molecular level in order to explain a polymerization state of molecules in a monomolecular liquid crystal alignment film after polarized light exposure in Example 3 of the present invention.

FIG. 9 is a conceptual cross-sectional view for explaining the manufacture of the liquid crystal display device according to the fourth embodiment of the present invention.

[Explanation of symbols]

1 substrate 2 Chemical adsorption liquid 3 Non-aqueous solvent for cleaning 4 Primary-oriented chemisorption monolayer 4'Photopolymerized chemisorption monolayer 5 Lifting direction from the cleaning liquid 6 Polarization direction 7 Polarizing film 8 UV irradiation light 9 Transparent electrode 10 'Photopolymerized chemisorption monolayer 11 First electrode group 12 transistor group 13 First substrate 14 color filter group 15 Second electrode 16 Second substrate 17 Liquid crystal alignment film 18 Spacer 19 adhesive 20 liquid crystal 21,12 Polarizer 23 Backlight

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-72483 (JP, A) JP-A-4-356020 (JP, A) JP-A-62-209415 (JP, A) JP-A-2- 214731 (JP, A) JP 56-24320 (JP, A) JP 5-178865 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G02F 1/1337

Claims (15)

(57) [Claims] 1. A chemical adsorbate comprising a base and a Si represented by the following formula (Formula 1) is, on the surface of the substrate, is coupled and fixed by chemisorption directly or via another film, and the chemical absorption
When the attached molecules are aligned in a predetermined direction, carbon-
A liquid crystal alignment film composed of a monomolecular film formed by cross-linking at a carbon double bond portion. [Chemical 1] (However, R1 and R2 are each hydrogen or a carbon number of 1 to
3 represents an alkyl group or an alkoxy group having 1 to 3 carbon atoms) 2. The substance constituting the coating is represented by the following formula (Formula 2) (where n represents an integer of 1 to 14), the following formula (Formula 3), (where n is an integer of 1 to 14). , R represents an alkyl group having 1 to 14 carbon atoms, or a phenyl group),
The following formula (Formula 4) (where n is an integer from 1 to 14 and R is an alkyl group having 1 to 14 carbon atoms or a phenyl group), and the following formula (Formula 5) (where n is from 1 to 14) The liquid crystal alignment film according to claim 1, comprising a chemical bond unit represented by at least one formula selected from an integer of 1 and R is an alkyl group having 1 to 14 carbon atoms or a phenyl group. [Chemical 2] [Chemical 3] [Chemical 4] [Chemical 5] Wherein contacting a chemisorption solution prepared from the first silane-based chemical adsorbate and a nonaqueous solvent having a proximal and a Si represented by the following (Formula 28) to the substrate, the chemical adsorption material By chemically adsorbing one end of the constituent molecule to the substrate surface, a first step of forming a monomolecular film coating bonded and fixed to the substrate surface, and by irradiating the substrate surface with ultraviolet rays or far ultraviolet rays, The adsorbed molecules are defined as
8) A second step of cross-linking via a bond of a vinyl group portion of the group shown in 8). [Chemical 28] (However, R1 and R2 are each hydrogen or a carbon number of 1 to
3 represents an alkyl group or an alkoxy group having 1 to 3 carbon atoms) 4. After the first step, a step of washing with an organic solvent, and standing up the substrate in a desired direction to drain the liquid,
4. The liquid crystal according to claim 3 , further comprising a step of primary-aligning the bond-fixed molecule, wherein in the second step, the group represented by the chemical formula 28 is cross-linked along a specific direction. Alignment film manufacturing method. 5. A polarizing plate for irradiating ultraviolet rays or far ultraviolet rays
Alternatively, the method for producing a liquid crystal alignment film according to claim 3 or 4 , which is performed through a transparent plate having a large number of groove scratches of about 0.1 to 0.3 µm on the surface. 6. A step of exposing a polarizing plate or a transparent plate whose surface has been rubbed with a patterned mask while irradiating with ultraviolet rays or far ultraviolet rays, and performing exposure, and in an alignment film in the same plane, each pixel is exposed. the different parts of the patterned alignment direction are provided a plurality of places, the manufacturing method of the liquid crystal alignment film according to any of claims 3 to 5. 7. In the first step, the first silane-based chemisorbed substance and a second silane-based chemisorbed substance having a molecular length different from that of the first silane-based chemisorbed substance are predetermined. were mixed in a ratio to produce the chemical adsorption solution, a method of manufacturing a liquid crystal alignment film according to any of claims 3 to 6. 8. The method for producing a liquid crystal alignment film according to claim 7 , wherein the second silane-based chemical adsorbent has a shorter molecular length than the first silane-based chemical adsorbent. 9. A pair of opposed substrates, a liquid crystal alignment film formed on the surface of at least an electrode of the pair of substrates, and a liquid crystal housed in a gap between the pair of opposed substrates. In the liquid crystal display device, the liquid crystal alignment film comprises a group represented by the following formula (Formula 29) and S
The chemisorbed material containing i and
Is bound and fixed by chemisorption through the film of
In the state that the chemisorbed molecules are oriented in a predetermined direction
Monomolecular film formed by cross-linking at a carbon-carbon double bond part
A liquid crystal display device characterized by comprising a film-like film . [Chemical 29] (However, R1 and R2 are each hydrogen or a carbon number of 1 to
3 represents an alkyl group or an alkoxy group having 1 to 3 carbon atoms) 10. The liquid crystal display device according to claim 9 , wherein an electrode is formed on each of inner surfaces of a pair of opposed substrates, and the liquid crystal alignment film is formed on each surface of both substrates. 11. The liquid crystal display device according to claim 9 , wherein the liquid crystal alignment film on the surface of the substrate has portions formed in a pattern and having different alignment directions. 12. The liquid crystal display device according to claim 9 , wherein a pair of electrodes is formed on the surface of one of the substrates. 13. A first substrate having a first electrode group mounted in a matrix form, or after forming an arbitrary thin film on the surface of the substrate, containing a carbon chain and terminating or part of the carbon chain. Is brought into contact with a chemical adsorbent prepared by using a first silane-based chemical adsorbent having a group represented by the following (Chemical Formula 30) and Si to chemically react the chemical adsorbent with the substrate surface, The first step of binding and fixing the adsorbent substance to the substrate surface, and the step of washing the substrate surface with an organic solvent, standing the substrate in a desired direction and draining the liquid, and pre-orienting the fixed molecules in the liquid draining direction. The second step is to irradiate ultraviolet rays or far ultraviolet rays to cross-link the adsorbed molecules along a specific direction through the bonds of the carbon-carbon double bond part of the group represented by the following (Chemical formula 30). 3 step, the first substrate, and the counter electrode A fourth step of aligning and adhering a second substrate which may be present with the electrode surface inside and maintaining a predetermined gap, and injecting a predetermined liquid crystal between the first and second substrates. 5th to do
And a step of manufacturing the liquid crystal display device. [Chemical 30] ( However, R1 and R2 in Chemical formula 30 are each hydrogen.
Or an alkyl group having 1 to 3 carbon atoms or 1 to 3 carbon atoms
Represents an alkoxy group. ) 14. In the third step, the step of exposing a polarizing plate with a patterned mask is performed, and a plurality of portions having different alignment directions are provided for each pixel in the alignment film in the same plane. wherein, the method according to claim 1 3. The 15. different portions of the alignment direction, and forming a pattern, a method of manufacturing a liquid crystal display device according to claim 1 4.