JP2001356348A - Method for manufacturing liquid crystal alignment film, liquid crystal display device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a liquid crystal alignment film to significantly improve the yield by suppressing contamination of the alignment film during the aligning treatment with light, and to provide a liquid crystal display device and a method for manufacturing the device by using that film. SOLUTION: After an empty cell 13 is assembled without exposing the substrates to air for a long time, the empty cell 13 is exposed to UV rays 10, 14 to indirectly align the liquid crystal alignment films. Since contamination of the liquid crystal alignment films can be suppressed by this method, the liquid crystal display device can be manufactured with improved yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a liquid crystal display device. More specifically, the present invention relates to a method for manufacturing a flat display panel using a liquid crystal for displaying a television (TV) image, a computer image, and the like.

[0002]

2. Description of the Related Art In recent years, in a process of manufacturing a liquid crystal display device, a study has been made to eliminate a rubbing treatment which is indispensable as a step of imparting liquid crystal alignment to an alignment film. Rubbing treatment is a type of liquid crystal alignment method, in which the substrate surface on which the alignment film is formed is rubbed with a roller to which a cloth such as nylon is adhered, thereby causing the alignment film surface to exhibit anisotropy. The liquid crystal is initially oriented in a desired direction. However, several disadvantages have been pointed out in the rubbing process, and the following are typical examples.

[0003] If the surface of the alignment film has irregularities, the concave portions will not rub, and especially if the panel has a large area, it will not rub uniformly, resulting in alignment defects, display unevenness, display burn-in, and the like. During the rubbing process, static electricity is generated on the alignment film, and the static electricity destroys a circuit such as a TFT to lower its function. During the rubbing process, dust is generated from the rubbing material (such as cotton cloth), and this dust causes display unevenness and non-uniform cell gap.

On the other hand, in a liquid crystal display device such as a twisted nematic mode, there is a problem that the viewing angle is narrower than in the past. In order to solve this problem, for example, Japanese Patent Application Laid-Open No. Hei 5-173135 discloses a method using a rubbing process. Specifically, by rubbing the alignment film in a certain direction, further covering the portion with a resist, and then rubbing in the opposite direction, forming a plurality of regions having different alignment directions of the liquid crystal. It is.

However, in order to form a plurality of sections having different liquid crystal alignment directions in the rubbing method (contact type), it is necessary to repeat a complicated operation of masking and rubbing each divided section. For this reason, according to the above technique, the production efficiency of the alignment film is greatly reduced, and the above-described problem such as generation of dust becomes more serious.

In order to solve the problems of the rubbing treatment as described above, various other orientation methods have been proposed in place of the rubbing treatment. In particular, recently, an orientation technique called "photo-alignment" has attracted attention. This photo-alignment method uses a polymer having a photosensitive group as an alignment film material, and uses a polarized UV
By irradiating light, desired anisotropy is expressed on the surface of the alignment film, and the liquid crystal is aligned using the anisotropy. That is, the biggest feature of the photo-alignment method is that it is “non-contact”, unlike the rubbing treatment. As a result, most problems that have conventionally occurred in the rubbing process can be solved.

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. Techniques for applying have been proposed. However, this technique requires a large amount of light energy for forming the groove. In addition, 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,
There has been proposed a technique for imparting orientation by irradiating linearly polarized light to a compound layer for forming an alignment film containing polyimide or a polyimide precursor to polymerize polyimide or the like. 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. Another problem is 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. 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, this technique cannot solve the above-mentioned problems such as a large film thickness and a small substrate fixing force. In addition, this technique requires that the alignment film for imparting a pretilt angle be irradiated with light obliquely, but a precise light irradiation device is required to accurately irradiate light obliquely. The production cost rises accordingly.

Here, it is also possible to form a plurality of regions having different alignment directions of the liquid crystal on the alignment film by applying the techniques described in the above-mentioned Japanese Patent Application Laid-Open No. 5-53118. However, each of the above techniques has problems such as a large film thickness and insufficient substrate fixing force as described above. Therefore, even if these techniques are used, a satisfactory alignment film cannot be provided.

In the above-mentioned conventional photo-alignment treatment,
When irradiating light, the alignment film was exposed to air for a long time. For this reason, contamination is caused by the attachment of contaminants and the like floating in the air, and an alignment film with a clean film surface cannot be obtained, which has been a major factor in lowering the yield.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems.
It is an object of the present invention to provide a method of manufacturing a liquid crystal alignment film that dramatically improves the yield by suppressing contamination of the alignment film when performing a light alignment process, a liquid crystal display device using the same, and a method of manufacturing the same. .

[0013]

According to a first aspect of the present invention, there is provided a method for manufacturing a liquid crystal alignment film, comprising the steps of: forming a liquid crystal alignment film comprising a molecule having a photosensitive group; The liquid crystal alignment film is subjected to photo-alignment treatment by exposing the transparent substrate from at least the transparent substrate side and / or the side surface of the transparent substrate.

According to the above-mentioned method, for example, in the case of performing a linear type continuous film formation, a liquid crystal alignment film is formed on a substrate placed on a line, and the light is irradiated from the back side to align the liquid crystal. Processing can be performed. As a result, it is not necessary to transport the substrate for performing the photo-alignment treatment, and the production efficiency can be improved, and the variation in manufacturing can be diversified.

Further, the above method does not exclude the case where the liquid crystal alignment film is directly irradiated with light to perform the optical alignment treatment. That is, the liquid crystal alignment film may be directly irradiated and the substrate side may be irradiated indirectly. Further, light may enter the substrate from the side surface side of the substrate. As a result, the photo-alignment treatment can be efficiently performed with a smaller amount of exposure than before, and the tact time can be shortened.

According to a second aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, comprising: bringing a compound having a photosensitive group into contact with a pair of transparent substrates; An alignment film forming step of forming a film, and after forming a frame-shaped sealing material lacking a portion of a liquid crystal injection port on one of the pair of substrates, the liquid crystal alignment film faces each other. An empty cell manufacturing step of bonding a pair of substrates with a predetermined gap, an exposure step of indirectly performing an optical alignment process on the liquid crystal alignment film by exposing the empty cell, and the liquid crystal injection port And a liquid crystal injecting step of injecting a liquid crystal material from above to form a liquid crystal layer.

According to the above-described method, immediately after the formation of the liquid crystal alignment film, the substrates are bonded to each other without performing the alignment treatment, thereby producing an empty cell. Further, after the empty cell is formed, the light alignment process is performed by exposing the empty cell from the outside. Therefore, it is possible to prevent the problem of contamination of the liquid crystal alignment film, which has conventionally been caused by exposing the liquid crystal alignment film to air for a long time during the alignment process. As a result of preventing contamination of the liquid crystal alignment film, it is possible to form a liquid crystal alignment film in which a decrease in liquid crystal alignment can be suppressed, and thereby it is possible to further improve the yield and manufacture a liquid crystal display device. Become.

According to a third aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device, comprising: bringing a compound having a photosensitive group into contact with a pair of transparent substrates; An alignment film forming step of forming a film, and after forming a frame-shaped sealing material on one of the pair of substrates, a liquid crystal material is dropped, and further, the pair of substrates are arranged so that the liquid crystal alignment film faces each other. And a step of exposing the liquid crystal cell to indirect light alignment treatment of the liquid crystal alignment film by exposing the liquid crystal cell.

According to the above method, a liquid crystal cell is manufactured by a so-called dropping method immediately after the formation of the liquid crystal alignment film without performing the alignment treatment. Further, after the liquid crystal cell is formed, a photo-alignment treatment is performed by exposing the liquid crystal cell from the outside. Therefore,
As described in the first aspect, contamination of the liquid crystal alignment film can be suppressed, and a liquid crystal display device can be manufactured with an improved yield.

According to a fourth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the second or third aspect, the exposing step comprises a step of indirectly exposing the entire surface of the liquid crystal alignment film. Further, a part of the liquid crystal alignment film is exposed.

In the above-mentioned method, the liquid crystal alignment film which has been subjected to the photo-alignment treatment in the alignment treatment step is again irradiated with spots after the production of an empty cell or a liquid crystal cell. The technical significance of this is that, for example, by re-exposing a region where a defective alignment such as disclination occurs in a part of the liquid crystal layer, the defective alignment can be repaired. In addition, when the position where the alignment defect occurs is known, the occurrence of the alignment defect can be prevented by performing spot irradiation in advance.

Further, if a part of the liquid crystal alignment film is exposed again, the liquid crystal alignment ability of the exposed portion can be selectively changed, thereby making it possible to partially change the alignment state of the liquid crystal.

According to a fifth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the second aspect, the exposing step comprises:
After indirectly exposing the entire surface of the liquid crystal alignment film, the liquid crystal alignment film is further exposed to the vicinity of a liquid crystal injection port and / or a sealing material.

When the liquid crystal material is injected from the liquid crystal injection port, factors such as coincidence between the major axis direction of the liquid crystal molecules and the flow direction of the liquid crystal material, collective properties of the liquid crystal, and the injection direction of the liquid crystal material are combined. Flow orientation occurs. This flow orientation appears near the liquid crystal injection port and near the sealing material.

However, as in the above-mentioned method, if the liquid crystal injection port and / or the vicinity of the sealing material where flow alignment is likely to occur are spotwise exposed, the liquid crystal alignment ability in the exposed liquid crystal alignment film region is repaired. Can be. This makes it possible to manufacture a liquid crystal display device in which the flow alignment is removed or its generation is suppressed.

According to a sixth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the third aspect, the exposing step comprises the steps of:
After indirectly exposing the entire surface of the liquid crystal alignment film, further exposing the liquid crystal alignment film near the sealing material.

The occurrence of the flow alignment is not limited to the case where the liquid crystal layer is formed by the liquid crystal injection method as in the case described in claim 5, but the case where the liquid crystal layer is formed by the dropping method. Also occurs near the sealing material. But,
By exposing the vicinity of the sealing material as in the above method, it is possible to repair the liquid crystal alignment ability in the area of the exposed liquid crystal alignment film,
As a result, it is possible to manufacture a liquid crystal display device in which the flow alignment is removed or its generation is suppressed.

According to a seventh aspect of the present invention, in the method for manufacturing a liquid crystal display device according to any one of the second to sixth aspects, the exposing step may be performed by any one of the pair of substrates. This is a step of irradiating light to the vicinity of the wiring provided on one side.

In the conventional liquid crystal display device, the size of the pixel has been reduced due to the progress of high definition, and as a result, there has been a problem of occurrence of poor alignment due to a horizontal electric field generated near the wiring when a voltage is applied. Was. However, by exposing the vicinity of the wiring in the exposing step as in the above method, the liquid crystal alignment ability in the exposed liquid crystal alignment film region can be repaired.
As a result, it becomes possible to remove the alignment defect due to the lateral electric field or to suppress the occurrence thereof.

According to an eighth aspect of the present invention, in the method of manufacturing a liquid crystal display device according to the second aspect, immediately after the exposing step or immediately after the empty cell producing step, the empty cell is formed into a predetermined shape. And performing a cutting step such that

To cut the empty cell into a predetermined shape,
This means that a large-sized laminated substrate is cut into a plurality of empty cells of a predetermined size. Therefore, if the cutting is performed after the exposure step as in the above method, the same kind of liquid crystal display device can be mass-produced in addition to the operation and effect described in claim 2.

On the other hand, if the empty cell is cut just after the empty cell forming step and immediately before the exposure step, it is possible to prevent foreign substances from being mixed in and prevent the liquid crystal alignment film from being contaminated. In addition, it can be manufactured with greatly improved yield.

The step of dividing the empty cell is not limited to the above-mentioned case of dividing the cell into a plurality of empty cells, but includes the step of taking out the liquid crystal injection port or the electrode portion.

According to a ninth aspect of the present invention, in the method of manufacturing a liquid crystal display device according to any one of the second to eighth aspects, the step of forming the alignment film includes the step of forming the photosensitive alignment film material. A chemical adsorption substance having a photosensitive group and one kind of functional group selected from the group of functional groups represented by the following chemical formula (1) is used, and a chemical adsorption liquid containing the chemical adsorption substance is brought into contact with the substrate surface. The step is a step of forming an organic thin film by chemically adsorbing the chemisorbed substance on a substrate surface.

Embedded image (However, A represents one kind of atom selected from the group consisting of silicon, germanium, tin, titanium and zirconium, and X represents one kind of functional group selected from halogen, alkoxy group and isocyanate group.)

When the chemically adsorbed substance has one kind of functional group selected from the above-mentioned functional group, when the chemically adsorbed liquid containing the chemically adsorbed substance is brought into contact with the substrate surface, the chemically adsorbed substance becomes And a functional group having active hydrogen present on the substrate surface. As a result, it becomes possible to form a liquid crystal alignment film having excellent adhesion and peeling resistance, which can be chemically adsorbed and firmly bonded to the substrate surface.

According to a tenth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to any one of the second to eighth aspects, the substrate is formed on the substrate immediately after the alignment film forming step. The method is characterized by including a removing step of removing existing non-adsorbed chemisorbed substances.

According to the above-described method, only the chemically adsorbed substance bonded to the substrate surface remains on the substrate after the removal step without being removed. As a result, a monomolecular liquid crystal alignment film is formed. be able to.

According to an eleventh aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the tenth aspect, the removing step comprises cleaning the substrate surface to which the chemically adsorbed substance is bonded with a non-aqueous solvent for cleaning. A washing step of washing, and further comprising, immediately after the washing step, a drain-drying step of setting the substrate in a predetermined direction and draining and drying the non-aqueous solvent.

When the non-aqueous solvent used in the washing step is used, the chemically adsorbed substance does not react with water in the solvent, so that the chemically adsorbed liquid is not deactivated.

Further, by performing the liquid draining and drying step, the thin film constituting molecules constituting the monomolecular liquid crystal alignment film can be provisionally aligned.

According to a twelfth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to any one of the second to eighth aspects, the alignment film forming step has a photosensitive group. The method is characterized by a step of forming a liquid crystal alignment film made of a polymer.

According to a thirteenth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the twelfth aspect, the main chain of the polymer having the photosensitive group is any one of polyvinyl, polysiloxane and polyimide. It is characterized by having one.

The invention according to claim 14 is the invention according to claim 10
The method for manufacturing a liquid crystal display device according to claim 13,
The photosensitive group is a chalcone skeleton group or a cinnamate skeleton group.

According to the above method, the chalcone skeleton group and the cinnamate skeleton group are excellent in photosensitivity, so that it is convenient to impart orientation by irradiation with polarized ultraviolet rays.

According to a fifteenth aspect of the present invention, in the method of manufacturing a liquid crystal display device according to any one of the second to fourteenth aspects, the exposing step is performed under reduced pressure. .

As in the above-described method, if the empty cells before the injection of the liquid crystal material are exposed under reduced pressure, the processing time can be reduced. Further, by placing the substrate under reduced pressure, removal of solvent molecules slightly remaining in the liquid crystal alignment film and other organic compound molecules attached to the liquid crystal alignment film can be promoted.

According to a sixteenth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to any one of the second to fifteenth aspects, the exposing step is a step of irradiating polarized light. Features.

According to the above method, the photosensitive groups can be photoreacted by irradiation of polarized light to polymerize in a specific direction. As a result, a liquid crystal alignment film capable of controlling the alignment of liquid crystal molecules in a specific direction can be formed.

According to a seventeenth aspect of the present invention, in the method for manufacturing a liquid crystal display device according to the sixteenth aspect, the exposing step irradiates the same region with polarized light a plurality of times at predetermined time intervals. Process.

According to the above-described method, by irradiating at predetermined time intervals, it is possible to prevent the substrate temperature from rising due to the application of light energy accompanying the irradiation.

According to an eighteenth aspect of the present invention, in the method of manufacturing a liquid crystal display device according to the sixteenth or seventeenth aspect, the exposing step comprises changing the incident angle with respect to the substrate a plurality of times to change the polarization. It is a step of performing irradiation.

According to the above method, it is possible to form a liquid crystal alignment film capable of controlling the pretilt angle of liquid crystal molecules for controlling alignment to a desired angle.

The nineteenth aspect of the present invention relates to the sixteenth aspect.
20. The method for manufacturing a liquid crystal display device according to claim 18, wherein a wavelength of the polarized light is in a range of 200 to 450 nm.

By using polarized light having a wavelength range within the above numerical range, a decomposition reaction as a side reaction that occurs when polarized light having a too short wavelength is used can be prevented.

According to a twentieth aspect of the present invention, there is provided a liquid crystal display device having a liquid crystal layer provided between a pair of transparent substrates. The non-transmissive portion and the transmissive portion of the applied light have different alignment states of the liquid crystal.

According to a twenty-first aspect of the present invention, in the liquid crystal display device according to the twentieth aspect, of the pair of substrates,
A plurality of wirings are provided inside one of the substrates, a light non-transmitting portion is the plurality of wiring portions, and the transmitting portion is a pixel region.

According to a twenty-second aspect of the present invention, in the liquid crystal display device according to the twentieth aspect, of the pair of substrates,
A plurality of wirings are provided inside one substrate, and a color filter layer is provided inside the other substrate, and the light non-transmitting portion is provided on the plurality of wiring portions and / or the color filter layer. And the transparent portion is a pixel region.

[0058]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
A description will be given based on FIG. In the following description, a liquid crystal display device having a monomolecular liquid crystal alignment film will be described as an example.

The method for manufacturing a liquid crystal display device according to the present invention comprises:
After forming an alignment film forming step of forming a liquid crystal alignment film on a pair of transparent substrates, and forming a frame-shaped sealing material lacking a liquid crystal injection port portion on one of the pair of substrates, An empty cell forming step of bonding the pair of substrates so that the alignment films face each other, an exposure step of indirectly performing an optical alignment process on the liquid crystal alignment film by exposing the empty cells, and A liquid crystal injecting step of injecting a liquid crystal material from an inlet to form a liquid crystal layer.

The alignment film forming step is a step of forming a liquid crystal alignment film on a substrate. Specifically, first, after preparing a chemisorption liquid containing a chemisorption substance having a photosensitive group,
The surface of the substrate is brought into contact with the chemisorption solution. This step is preferably performed in a dry atmosphere having a relative humidity of 35% or less, for example, in dry air, dry nitrogen, or dry helium. Examples of the contacting method include a method of applying a chemically adsorbed liquid to a substrate, a method of dipping the substrate in the solution, and a method of vaporizing the chemically adsorbed solution so that the chemically adsorbed substance comes into contact with the substrate surface and a thin film is formed by a gas phase reaction. And the like.

As the above substrate, a substrate having a surface functional group having active hydrogen exposed on its surface can be used. Specifically, for example, a glass substrate, a resin substrate, or the like can be given. Examples of the surface functional group having active hydrogen include a carboxyl group, a sulfinic acid group, a sulfonic acid group, a phosphoric acid group, a phosphorous acid group, a thiol group, and an amino group, in addition to the above-described hydroxyl group. Furthermore, the active hydrogen of the functional group may be a functional group substituted with an alkali metal or an alkaline earth metal, respectively. Further, when the functional group having active hydrogen does not exist on the surface of the base or is small, the UV / ozone treatment, the oxygen plasma treatment,
It is appropriate to apply a compound oxidizing agent treatment such as an excimer UV treatment or a potassium permanganate treatment to modify the surface of the substrate to introduce the above-mentioned functional groups or to increase the number of the functional groups.

As the alignment film material for forming the liquid crystal alignment film, a photosensitive alignment film material alone may be used, or a mixture of two or more kinds of other materials with the photosensitive alignment film material may be used. May be.

Examples of the photosensitive functional group include a chalcone skeleton group and a cinnamoyl group. Further, as the chemisorbing substance having the photosensitive group, a chemisorbing substance having one kind of functional group selected from the group of functional groups represented by the following chemical formula (1) can be used.

Embedded image (However, A represents one kind of atom selected from the group consisting of silicon, germanium, tin, titanium and zirconium, and X represents one kind of functional group selected from halogen, alkoxy group and isocyanate group.)

The above-mentioned chemisorbing substance is constituted by linking the following functional groups to one kind of functional group selected from the group of functional groups represented by the above chemical formula (1).

1. Methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group,
n-heptyl group, n-octyl group, n-nonyl group, n-
Decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group, n-heptadecyl group, n-octadecyl group, n-nonadecyl group, n- Eicosyl group,
Hydrocarbon groups such as phenyl groups;

A hydrocarbon group containing a carbon-carbon double bond or a carbon-carbon triple bond as a part of the hydrocarbon group of 2.1.

The hydrogen in the hydrocarbon group of 3.1 and 2 is replaced with another functional group (for example, methyl group, ethyl group, methyl halide group, hydroxyl group, cyano group, amino group, imino group, carboxyl group, ester group, Thiol groups, aldehyde groups, etc.) and / or atoms (for example, F, Cl, Br, I
Etc.) substituted functional group.

4.1 CC in the hydrocarbon groups of 1 and 2
Part of the (carbonyl) bond is C—O—C (ether)
A functional group substituted by a bond, a C—CO—C (carbonyl) bond, or a C ＝ N bond.

Next, in the present invention, a removing step for removing unreacted chemically adsorbed substances remaining on the substrate can be performed. Specifically, for example, a method of washing away the unreacted chemically adsorbed substance with a nonaqueous solvent for washing may be used.

As the above-mentioned cleaning agent, an aprotic solvent,
A protic solvent or a mixed solvent thereof can be used.
However, it is often preferable to use a solvent containing as little water as possible. The aprotic solvent is not particularly limited, but may be a chlorine-based solvent such as chloroform, an aromatic solvent such as benzene or toluene, a lactone-based solvent such as γ-butyl lactone, or an ester-based solvent such as ethyl acetate. Is mentioned. The proton solvent is not particularly limited, and examples thereof include alcohol solvents such as methanol and ethanol.

The solvents listed above generally contain a large amount of flammable substances, so that when such a solvent is used, explosion-proof means may be provided if necessary. Also, this step needs to be performed in a dry atmosphere at a relative humidity of 35% or less, similarly to the above-described alignment film forming step. This is because the unadsorbed molecules react with moisture in the air and become cloudy.

Further, immediately after the washing step, a drain-drying step may be performed in which the substrate is set in a certain direction and the non-aqueous solvent is drained and dried. This step is a step of bringing a non-aqueous solvent into contact with the substrate surface to which the chemically adsorbed substance has been adsorbed, and then draining and drying the non-aqueous solvent in a certain direction.
More specifically, for example, on the substrate after the formation of the liquid crystal alignment film, a portion to be drained and dried is immersed in a solvent tank for a certain period of time. At this time, the immersion is performed so that the liquid surface and the substrate have a substantially vertical relationship. Next, the immersed substrate is pulled up in the vertical direction. At this time, the liquid is sequentially drained and dried on the surface of the liquid crystal alignment film as the substrate is pulled up. As a result, molecules constituting the liquid crystal alignment film can be provisionally aligned. This step plays a role as a primary alignment treatment when it is preferable to perform an alignment treatment to some extent before the alignment treatment by light irradiation. The draining and drying step is not limited to the method described above, and various other methods can be employed.

The empty cell forming step is performed after forming a liquid crystal alignment film on a substrate. That is, in the present invention, unlike the conventional manufacturing process, the process shifts to the production of an empty cell without performing the optical alignment treatment. As a result, since the liquid crystal alignment film is not exposed to the air for a long time during the alignment treatment, contamination of the liquid crystal alignment film can be prevented, for example, by preventing adhesion of foreign substances from the air. In this step, in order to secure a liquid crystal injection port for injecting a liquid crystal material into an empty cell, a frame-shaped sealing material having a coating shape lacking the portion is formed in advance. At this time, if the board uses a large-sized board for multiple
A plurality of the frame-shaped sealing materials may be formed in a matrix.

The above-mentioned exposure step is a step performed for selectively photopolymerizing the photosensitive group of the constituent molecules of the thin film constituting the liquid crystal alignment film by light irradiation. Thereby, the thin film constituent molecules on the substrate surface can be cross-linked in a specific direction, and the orientation of the thin film constituent molecules can be fixed. As a result, thermal stability, chemical stability, and the like can be improved.

Here, the exposure may be performed from one side of the empty cell or from both sides. When the irradiation is performed from one side, the irradiation may be performed from one substrate side, and then the exposure may be performed alternately, such as from the other substrate side. When the exposure is performed from both sides, the exposure may be performed at the same time, or the exposure may be performed with a time difference. If the light source is arranged only on one side of the empty cell and you want to expose both sides of the empty cell, you can expose the empty cell by turning it over, or use a mirror or the like without inverting the empty cell. A method of exposing the opposite surface of an empty cell by reflecting light using a method.
When one light source is arranged on each side of the empty cell, the irradiation may be performed simultaneously or with a time difference.

The light used in this step is preferably polarized light, and more preferably linearly polarized light. Specific methods for irradiating linearly polarized light include, for example, a method of irradiating light through a commonly used absorption-type polarizing plate, a method of irradiating light through a non-absorption-type polarization separation element such as a polarizing beam splitter, and the like. But are not particularly limited to these. The wavelength of the polarized light may be any wavelength that is suitable for the photosensitive group to cause a photoreaction, and usually uses light having a wavelength range in the ultraviolet region, but the present invention is not limited to this. is not. Specifically, for example, the wavelength range of the light used in this step may be in the range of 200 to 450 nm. This is because, when the main reaction by light irradiation is a crosslinking reaction or a polymerization reaction, if the wavelength of the irradiation light is too short, on the contrary, a decomposition reaction is likely to occur as a side reaction. Further, the exposure temperature may be from room temperature to about 100 ° C. or lower, but is not limited thereto.

In this step, at a predetermined time interval,
The same region of the liquid crystal alignment film may be irradiated with polarized light a plurality of times.
Thus, it is possible to prevent the substrate temperature from increasing due to the application of light energy accompanying the irradiation. Further, in this step, it is also possible to perform polarized light irradiation a plurality of times by changing the incident angle and the irradiation amount with respect to the substrate. Thus, for example, when an organic thin film is used as the liquid crystal alignment film, the pretilt angle of the liquid crystal molecules whose alignment is regulated can be controlled to a desired angle. further,
This step may be performed under reduced pressure. For example, if exposure is performed under reduced pressure on an empty cell before injecting a liquid crystal material, the process time can be reduced. Further, by placing the substrate under reduced pressure, removal of solvent molecules slightly remaining in the liquid crystal alignment film and other organic compound molecules attached to the liquid crystal alignment film can be promoted. Here, the solvent molecules refer to solvent molecules contained in the chemical adsorption solution used in the alignment film forming step.

The liquid crystal injection step is a step of forming a liquid crystal layer by injecting a liquid crystal material from a liquid crystal injection port. Examples of the liquid crystal material include a nematic liquid crystal, a smectic liquid crystal, a discotic liquid crystal, and a ferroelectric liquid crystal, and a nematic liquid crystal is particularly preferable. Examples of the nematic liquid crystal include biphenyl, terphenyl, azoxy, Schiff base, phenylcyclohexane, biphenylcyclohexane, ester, pyrimidine, dioxane, bicyclooctane, and cubane.

In the present invention, an alignment treatment step of irradiating the entire surface of the liquid crystal alignment film with light to perform an alignment treatment is performed immediately after the alignment film formation step. Light irradiation can be performed on a part of the liquid crystal alignment film. In this way, by further performing spot irradiation on the liquid crystal alignment film that has already been subjected to the photoalignment treatment, for example, a region in which alignment defects such as disclination occur in a part of the liquid crystal layer or a region in which alignment failure is likely to occur may occur. Repair is possible. Specifically, as shown in FIG. 1A, when a liquid crystal material is injected into the empty cell 1 by a liquid crystal injection method, flow alignment occurs near the liquid crystal injection port 2 and / or the sealing material 3. By exposing such a portion, the liquid crystal alignment ability of the liquid crystal alignment film can be repaired, and the flow alignment can be reduced. Further, when various wirings for transmitting signals for driving the liquid crystal are provided on the substrate, there is a problem that poor alignment occurs due to a lateral electric field generated near the wirings when a voltage is applied. However, in the above-mentioned exposure step, even in such a case, the exposure of the wiring and the vicinity thereof can reduce the alignment defect. Also, when it is desired to partially change the alignment state of the liquid crystal, the region of the liquid crystal alignment film corresponding thereto can be processed so as to have a new liquid crystal alignment state by exposing it again.

Further, when a liquid crystal layer is formed by a dropping method, as shown in FIG. 1B, a liquid crystal material is dropped after forming a frame-shaped sealing material 3 on a substrate 4. In some cases, flow orientation may occur near 3. Also in such a case, the flow orientation can be reduced by exposing the vicinity of the sealing material 3 as described above.

As described above, in the present invention, since the optical alignment treatment is performed while suppressing the contamination of the liquid crystal alignment film, it is possible to manufacture a liquid crystal display device with an improved yield.
Further, the liquid crystal display device manufactured as described above requires an STN (Super Twisted Nema) which requires strict gap accuracy.
tic) mode, etc.

In the liquid crystal display device manufactured by the manufacturing method according to the present invention, since the optical alignment processing is performed from the empty cell or the outside of the liquid crystal cell, the optical alignment processing of the liquid crystal alignment film is not performed in the light-shielded portion. Therefore, the alignment state of the liquid crystal is different between the light non-transmission portion and the light transmission portion. Specifically, in the case where a plurality of wirings such as gate lines and source lines are provided on the inside of the substrate and a wiring made of a metal material such as aluminum is provided, when exposure is performed from the substrate side, a liquid crystal alignment film is formed. It is not exposed at the projected portion of the wiring. Therefore, the projected portion has a different alignment state of the liquid crystal as compared with other regions.
Further, even in the case of a substrate with a color filter provided with a color filter layer composed of R, G, B and a black matrix, the projected portion of the black matrix in the liquid crystal alignment film is not exposed. The alignment state of the liquid crystal is different in comparison.

(Other Matters) The case where the liquid crystal alignment film is a monomolecular film has been described above, but the present invention is not limited to this. For example, it may be a polymer film containing a polymer having a photosensitive group. Here, as the polymer having a photosensitive functional group, a polymer having polyvinyl, polysiloxane, or polyimide in its main chain is preferable.

In the above description, the case where a single-leaf liquid crystal display device is manufactured has been described. However, in the case where a large-sized substrate for multi-paning is used as a substrate, a plurality of liquid crystal display devices must be manufactured simultaneously. Is also possible. In this case, it is necessary to perform a step of cutting the empty cell into a predetermined shape immediately after the empty cell forming step or immediately after the exposure step. Further, it is necessary to form a plurality of frame-shaped seal materials in a matrix. Further, in the step of dividing the empty cell, division for extracting a liquid crystal injection port or an electrode portion may be performed.

[0085]

The present invention will be described more specifically below with reference to examples.

Example 1 (1) Liquid Crystal Alignment Film Forming Process A glass substrate 5 (containing a large number of hydroxyl groups on the surface) having a transparent electrode formed on the surface is prepared and thoroughly washed and degreased in advance. Next, a chemical adsorption solution having a concentration of about 1% by weight was prepared using the following chemical formula (2) and an aprotic solvent. A mixed solvent of a well-dehydrated siloxane-based solvent (trade name: KF96L, manufactured by Shin-Etsu Chemical Co., Ltd.) and chloroform was used as the aprotic solvent.

Embedded image

Subsequently, as shown in FIG.
% Of the glass substrate 5 was immersed in the chemical adsorption solution 6 for about 1 hour in a dry atmosphere of not more than 1%. As a result, the SiCl group of the chlorosilane-based chemisorbed substance and the OH group on the substrate surface are dehydrogenated.
The Cl reaction was carried out, and the chlorosilane-based chemically adsorbed substance was firmly bonded to the surface of the glass substrate 5. In addition, chemical adsorption liquid 6
Instead of the immersion method, a method of applying the chemical adsorption liquid 6 to the surface of the glass substrate 5 may be adopted.

Thereafter, the substrate was taken out of the chemical adsorption solution 6 and washed with chloroform 7 (cleaning agent) which is a well-dehydrated water-free aprotic solvent. As a result, unreacted chlorosilane-based chemically adsorbed substances were removed from the glass substrate 5. That is, a monomolecular layered thin film could be formed by washing.

Further, this glass substrate 5 was washed with chloroform 7
The cleaning liquid was drained and dried while the glass substrate 5 was set upright in a dry atmosphere (see FIG. 3). As a result, the adsorbed molecules fixed on the glass substrate 5 were able to be primarily oriented along the cleaning solution draining direction 9.

Next, the surface of the glass substrate 5 was exposed to air containing humidity. As a result, the remaining Cl of the SiCl group is subjected to a dehydrochlorination reaction with moisture in the air, and the following chemical formula 3
As shown in the figure, the adsorbed molecules were siloxane-bonded.
As described above, a monomolecular film-like chemical adsorption film (liquid crystal alignment film) was formed.

Embedded image

The thickness of the monomolecular film prepared above was measured by an ellipsometer (with a refractive index of 1.45) and found to be about 25 nm.

(2) Empty cell assembling process Two substrates 11 and 12 each having a liquid crystal alignment film on which a liquid crystal alignment film was formed in the liquid crystal alignment film forming process were prepared, and an empty cell was formed using these substrates 11 and 12. Was prepared. That is,
A sealing material is applied to the substrate 11 so as to form a frame shape lacking a liquid crystal injection port, and further a resin spacer (diameter 12 μm) is applied.
m). Next, the substrate 11 and the substrate 12 are bonded together such that the liquid crystal alignment films face each other, and
No. 3 was produced (see FIG. 4). At this time, the alignment was performed so that the inclination directions of the adsorbed molecules constituting the liquid crystal alignment film (cleaning liquid removal direction 9) were parallel and opposite to each other, that is, antiparallel.

(3) Photo-alignment process The polarization axis of the empty cell 13 produced in the empty cell assembling process is parallel to the tilt direction of the adsorbed molecules in the liquid crystal alignment film (cleaning liquid draining direction 9). As described above, a Grantler-type polarizer (not shown) was arranged, and light irradiation was performed from the substrate 12 side. A high-pressure mercury lamp of 500 W was used as a light source, and the initial irradiation intensity was 480 mJ / cm ² for ultraviolet light 10
(Main wavelength: 365 nm). The irradiation intensity after transmission through the Grantler-type polarizer was 2.1 mW / cm ² . Next, ultraviolet light 14 was irradiated from the substrate 11 side under the same irradiation conditions as above.

(4) Liquid Crystal Injection and Annealing Process The nematic liquid crystal (ZLI4792; manufactured by Merck) was injected into the empty cell 13 subjected to the photo-alignment treatment at normal temperature and normal pressure. Thereafter, the liquid crystal cell was annealed at 120 ° C. for 30 minutes, and gradually cooled to room temperature. Thus, a liquid crystal cell was completed.

(5) Evaluation of Liquid Crystal Cell A pair of polarizing plates was arranged in the above liquid crystal cell so as to be in a crossed Nicols state, and the alignment of the liquid crystal was evaluated. As a result, it was confirmed that the disclination was extremely small and the blackness at the time of black display was extremely dark. Further, as a result of various investigations on the characteristics of the liquid crystal cell, the pretilt angle was 1
コ ン ト ラ ス ト, the contrast (5 V) was 330, and the voltage holding ratio was 98.5%.

As described above, after the formation of the liquid crystal alignment film, an empty cell is produced without performing the optical alignment treatment, and then the liquid crystal cell exhibiting extremely good liquid crystal alignment is obtained by performing the optical alignment treatment from outside the empty cell. Can be produced.

Here, when it is desired to selectively change the orientation direction, a patterned mask is prepared, and the mask is superimposed on a polarizing plate. Then, the mask is irradiated with 365 to 400 mJ / cm ² of ultraviolet light.
When ultraviolet light having a wavelength of nm is irradiated, the alignment direction changes only in the irradiated portion, and the liquid crystal is formed along the portions having different alignment directions in a pattern in the alignment film in the same plane, that is, along the cleaning solution draining direction 9 and the polarization direction. A plurality of orienting portions could be provided.

Further, through a mask prepared so as to irradiate polarized light to a small section obtained by dividing one pixel unit into a plurality of parts, and by changing the positional relationship between the thin film surface and the polarization direction each time, a plurality of times are performed. By irradiating with ultraviolet light, a liquid crystal cell with multi-domain alignment in one pixel could be produced.

Example 2 In Example 2, a liquid crystal display device was manufactured using the liquid crystal alignment film as described above. Hereinafter, a manufacturing process of the liquid crystal display device will be described with reference to FIG.

First, as shown in FIG. 4, a first electrode group 21 mounted in a matrix and a T
A second substrate having a first substrate 20 having an FT (Thin Film Transistor) group 22 and a color filter group 25 and a second electrode 26 (a counter electrode) placed so as to face the first electrode group 21. A chemically adsorbed liquid prepared according to the same procedure as in Example 1 was applied onto the substrate 24 of Example 1 to produce a similar chemically adsorbed monomolecular film. Thereby, the liquid crystal alignment film 23 re-aligned along the electrode pattern as in the first embodiment,
27 were produced.

Next, the first substrate 20 and the second substrate 2
No. 4 was aligned and bonded so that the electrodes faced each other, thereby producing an empty cell. At this time, the alignment processing directions in the liquid crystal alignment film 23 and the liquid crystal alignment film 27 were set to 90 degrees with each other.

Next, a grantler-type polarizer (not shown) was disposed in the same manner as in the first embodiment, and the initial irradiation intensity was 480 mJ / cm ² from both surfaces of the first substrate 20 and the second substrate 24. (Main wavelength: 365 nm). The irradiation intensity after transmission through the Grantler-type polarizer was 190 mW / cm ² .

Thereafter, the TN liquid crystal (ZLI4
792; Merck) to form the liquid crystal layer 28,
A liquid crystal panel was manufactured. Further, polarizing plates 31 and 32 were disposed on both outer sides of the panel, and a backlight 33 was disposed on the first substrate 20 side, thereby completing a liquid crystal display device.

In the above liquid crystal display device, the first substrate 2
When an image was displayed while illuminating the backlight 33 from the 0 side, a clear image with excellent brightness could be displayed.

(Other Matters) In each of the above embodiments, chloroform, which is an aprotic solvent containing no water, was used as the cleaning agent used in the liquid crystal alignment film forming process. Is not limited to this. That is, any solvent can be used as long as the solvent does not contain water and the surfactant is soluble. For example, a solvent including a substance having a fluorocarbon group, a carbon chloride group, or a siloxane group, specifically, Freon 113, chloroform,
Hexamethyldisiloxane and the like.

Further, the liquid crystal alignment film according to the present invention contains a chemical bond unit represented by the following chemical formula (4).
The alignment film containing the chemical bond unit represented by (4) has a strong alignment control force with respect to a twisted nematic (TN) type liquid crystal, and has a high alignment effect. Therefore, the present invention can be particularly suitably applied to this type of liquid crystal display device.

Embedded image

In this case, as the non-aqueous organic solvent for preparing the chemical adsorption liquid, a solvent comprising a substance containing an alkyl group, a carbon fluoride group, a carbon chloride group or a siloxane group can be suitably used. This is because the chemically adsorbed substance having the chemical bonding unit represented by the chemical formula (4) is soluble in these non-aqueous organic solvents.

[0108]

As described above, according to the present invention, since the liquid crystal alignment film after film formation is subjected to photo-alignment treatment without exposing it to the air, contamination of the liquid crystal alignment film in the manufacturing process is suppressed. be able to. As a result, it is possible to manufacture a liquid crystal display device with an improved yield as compared with the conventional manufacturing method.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a state of occurrence of flow orientation.

FIG. 2 is a conceptual diagram for explaining formation of a liquid crystal alignment film according to Example 1 of the present invention, and shows a state where a substrate is immersed in a chemical adsorption solution.

FIG. 3 is a conceptual diagram for explaining formation of a liquid crystal alignment film according to Example 1 of the present invention, and shows a state of cleaning a substrate.

FIG. 4 is a conceptual diagram for explaining a photo-alignment treatment of a liquid crystal alignment film according to Example 1 of the present invention.

FIG. 5 is a sectional view schematically showing a liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Chemical adsorption liquid 3 Chloroform (non-aqueous solvent) 9 Cleaning liquid removal direction 9 Ultraviolet light 11, 12 Substrate with liquid crystal alignment film 13 Empty cell 14 Ultraviolet light 20 First substrate 21 First electrode group 22 TFT group 23 27 liquid crystal alignment film 24 second substrate 25 color filter group 26 second electrode 28 liquid crystal layer 31, 32 polarizing plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukio Nomura 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Tsuyoshi Uemura 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Mariko Kawaguri 1006 Okadoma Kadoma, Kadoma City Osaka Pref. 1006 Kadoma, Kamon, Fumonma Matsushita Electric Industrial Co., Ltd.F-term (reference)

Claims (22)

[Claims] 1. The method according to claim 1, wherein a transparent substrate on which a liquid crystal alignment film containing molecules having a photosensitive group is formed is exposed from at least the transparent substrate side and / or a side surface of the transparent substrate. A method for producing a liquid crystal alignment film, comprising subjecting a liquid crystal alignment film to a photo-alignment treatment. 2. An alignment film forming step in which a compound having a photosensitive group is brought into contact with a pair of transparent substrates to form a liquid crystal alignment film. After forming a frame-shaped sealing material lacking a portion of a liquid crystal injection port, an empty cell forming step of bonding the pair of substrates with a predetermined gap so that the liquid crystal alignment films face each other; An exposure step of indirectly photoaligning the liquid crystal alignment film by exposing the cell to light; and a liquid crystal injection step of injecting a liquid crystal material from the liquid crystal injection port to form a liquid crystal layer. Manufacturing method of a liquid crystal display device. 3. An alignment film forming step of forming a liquid crystal alignment film by bringing a compound having a photosensitive group into contact with a pair of transparent substrates, and forming a frame on one of the pair of substrates. A liquid crystal material is dropped after forming a seal material in a shape, and a liquid crystal cell manufacturing step of bonding the pair of substrates with a predetermined gap so that the liquid crystal alignment films face each other; An exposure step of indirectly subjecting the liquid crystal alignment film to a photo-alignment treatment by exposing the liquid crystal display to light. 4. The method according to claim 2, wherein in the exposing step, after indirectly exposing the entire surface of the liquid crystal alignment film, further exposing a part of the liquid crystal alignment film. A method for manufacturing a liquid crystal display device. 5. The method according to claim 2, wherein in the exposing step, after indirectly exposing the entire surface of the liquid crystal alignment film, further exposing the liquid crystal alignment film in the vicinity of a liquid crystal injection port and / or a sealing material. 3. The method for manufacturing a liquid crystal display device according to 1. 6. The liquid crystal display device according to claim 3, wherein in the exposing step, after indirectly exposing the entire surface of the liquid crystal alignment film, further exposing the liquid crystal alignment film near a sealing material. Manufacturing method. 7. The method according to claim 2, wherein the exposing step is a step of irradiating light near a wiring provided on one of the pair of substrates.
13. The method for manufacturing a liquid crystal display device according to item 10. 8. The liquid crystal display device according to claim 2, wherein a step of cutting the empty cell into a predetermined shape is performed immediately after the empty cell forming step or immediately after the exposure step. Manufacturing method. 9. The method for forming an alignment film according to claim 1, wherein the step of forming the alignment film comprises a photosensitive group and a functional group represented by the following chemical formula (1).
A chemisorption solution containing a chemisorption substance having a kind of functional group,
The method according to any one of claims 2 to 6, further comprising a step of forming a liquid crystal alignment film by causing the chemical adsorption substance to chemically adsorb to the substrate surface by being brought into contact with the substrate surface. A method for manufacturing a liquid crystal display device. Embedded image (However, A represents one kind of atom selected from the group consisting of silicon, germanium, tin, titanium and zirconium, and X represents one kind of functional group selected from halogen, alkoxy group and isocyanate group.) 10. The method according to claim 2, further comprising a step of removing a non-adsorbed chemically adsorbed substance present on the substrate immediately after the step of forming the alignment film. 3. The method for manufacturing a liquid crystal display device according to item 1. 11. The removing step is a washing step of washing the surface of the substrate to which the chemically adsorbed substance is bound with a non-aqueous solvent for washing. The method of manufacturing a liquid crystal display device according to claim 10, further comprising a drain drying step of draining and drying the non-aqueous solvent. 12. The method according to claim 2, wherein the step of forming an alignment film is a step of forming a liquid crystal alignment film made of a polymer having a photosensitive group. A method for manufacturing a liquid crystal display device. 13. The method for manufacturing a liquid crystal display device according to claim 10, wherein the polymer having the photosensitive group has any one of polyvinyl, polysiloxane, and polyimide in a main chain. 14. The method according to claim 7, wherein the photosensitive group is a chalcone skeleton group or a cinnamate skeleton group.
A method for manufacturing a liquid crystal display device according to claim 11. 15. The method for manufacturing a liquid crystal display device according to claim 2, wherein the exposing step is performed under reduced pressure. 16. The method according to claim 2, wherein the exposing step is a step of irradiating polarized light.
13. The method for manufacturing a liquid crystal display device according to item 10. 17. The method according to claim 14, wherein the exposing step is a step of irradiating the same region with polarized light a plurality of times at predetermined time intervals. 18. The method for manufacturing a liquid crystal display device according to claim 14, wherein the exposing step is a step of performing irradiation of polarized light a plurality of times while changing an incident angle with respect to the substrate. . 19. The wavelength of the polarized light is 200 to 450 nm.
14. The method according to claim 14, wherein
7. The method for manufacturing a liquid crystal display device according to any one of 6. 20. A liquid crystal display device in which a liquid crystal layer is provided between a pair of transparent substrates, wherein a liquid crystal alignment state is different between a light non-transmission part and a light transmission part in the liquid crystal layer. A liquid crystal display device characterized by the above-mentioned. 21. A plurality of wirings are provided inside one of the pair of substrates, the non-light-transmitting portion is the plurality of wiring portions, and the transmitting portion is a pixel region. 3. The method according to claim 2, wherein
The liquid crystal display device according to 0. 22. Among the pair of substrates, a plurality of wirings are provided inside one of the substrates, and a color filter layer is provided inside the other substrate. 21. The liquid crystal display device according to claim 20, wherein a plurality of wiring portions and / or a black matrix portion in the color filter layer, and the transmission portion is a pixel region.