JPH11218763A - Manufacturing method of liquid crystal display element - Google Patents

Abstract

(57) Abstract: A liquid crystal display device having a grating-shaped alignment film is provided. A method of manufacturing a liquid crystal display element in which liquid crystal is sandwiched between a pair of glass substrates having a liquid crystal alignment film, wherein a photopolymerizable monomer on a surface of a glass substrate in contact with the liquid crystal is irradiated with grating-like pattern light. And forming a liquid crystal alignment film by applying the method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for a monitor of a computer or the like.

[0002]

2. Description of the Related Art A liquid crystal display device is already known as a device in which a liquid crystal layer is provided in a gap between two glass substrates with electrodes and characters, numerals, figures, pictures, etc. are displayed by an electro-optic effect. Currently known TN (Twisted Nematic),
STN (Supertwisted Nematic), FLC (Ferroelectr
ic Liquid crystal), IPS (In-Plane switching)
In the method of manufacturing a liquid crystal display element such as a mode, an alignment process such as rubbing is provided on a glass substrate with two electrodes, spacer beads are scattered on the substrate, and the substrates are bonded together using a sealant. Through a step of injecting a liquid crystal material into the gap.

At present, in this alignment treatment, a polymer film made of polyimide, polyvinyl alcohol, or the like is formed on a transparent electrode, and the surface is rubbed with a roller to which a cloth or the like is attached so that the surface has an alignment ability. The applied rubbing method is most frequently used.

However, the rubbing method has problems such as contamination of rubbing dust and the like and generation of static electricity on the liquid crystal alignment film. In particular, the generation of static electricity is caused by the TFT (TFT) of an active matrix type liquid crystal display element. Therefore, a new alignment treatment method is desired because the thin film transistor is destroyed.

[0005] As an alignment treatment method that can replace the rubbing method,
There is known a method of irradiating a photosensitive polymer on a substrate with light in the form of a grating to form linear grooves at regular intervals to generate liquid crystal alignment ability (hereinafter, referred to as a grating method). This grating method is based on the fact that when liquid crystal molecules are placed on a substrate having linear grooves formed at regular intervals, the liquid crystal molecules are aligned in the direction along the macro grooves (M. Nakamura et al., J. Appl. Phys, 52,
210 (1981)).

Japanese Patent Application Laid-Open No. 1-210932 discloses a method of irradiating a polyimide film surface with a pattern of ultraviolet rays, forming a grating-like groove by decomposition, and performing an alignment treatment. Japanese Patent Application Laid-Open No. 2-196219 discloses a method of irradiating the surface of a polymer film with a laser beam in a stripe shape, scattering the polymer, forming a grating-like groove in the polymer film, and performing an alignment treatment. Have been. Japanese Patent Application Laid-Open No. 60-60624 discloses a method of irradiating a photosensitive polyimide polymer film with interference light, forming a grating-like groove in the polymer film using a crosslinking reaction, and performing an alignment treatment. I have.

In each of these methods, since a polymer film is used, the number of steps is large, including a polymer thin film forming step, a drying step, an exposure step, a step of removing an unexposed portion or an irradiated portion, and the like. There is a problem that each process time is long and productivity is poor. In addition, the amount of exposure must be large, and particularly when laser light is used, it is necessary to irradiate the laser light with high power. Furthermore, since polymers that are difficult to reprocess are handled, the members cannot be reused, leading to high costs. Particularly, in the method in which the exposed portion is decomposed or scattered, no reuse is considered.

[0008]

As described above, a number of alignment treatments by the grating method have been studied as an alternative to the rubbing method. However, the process is complicated, a large amount of light is consumed, and the member is not easily processed. Due to the high cost of rubbing, the rubbing method has not yet been put to practical use.

[0009] The object of the present invention is to address such a problem.
A grating-like liquid crystal alignment film having a sufficient alignment ability for liquid crystal molecules can be easily formed without causing contamination of the substrate and the like, as in the conventional rubbing method, requires only a small amount of exposure, and requires re-use of members. Provided is a method for manufacturing a liquid crystal display element that can be used.

[0010]

According to the present invention, there is provided a method of manufacturing a liquid crystal display device in which a liquid crystal is sandwiched between a pair of glass substrates having a liquid crystal alignment film. The method includes a step of forming the liquid crystal alignment film by irradiating a grating-shaped pattern light to the photopolymerizable monomer on the substrate surface. According to the present invention, a photopolymerizable monomer is used in place of the conventional photosensitive polymer or polymer film, so that the time spent for the thin film forming step, the drying step, and the washing step is greatly reduced, A method for manufacturing a liquid crystal display element that can be formed as easily as the rubbing method can be provided.

According to the second aspect of the present invention, since a liquid photopolymerizable monomer is used instead of a photosensitive polymer or a polymer film, a drying step is unnecessary, and the time spent in a cleaning step is greatly reduced. In addition to being reduced, the time spent in the thin film formation process is also significantly reduced. In addition, since the liquid photopolymerizable monomer can be easily recovered, the members can be reused and the cost can be reduced.

In claim 3 of the present invention, since a gaseous photopolymerizable monomer is used instead of a photosensitive polymer or a polymer film, none of the thin film forming step, drying step and washing step are required. Thus, the time spent for forming the alignment film is greatly reduced. Further, since only the photopolymerizable monomer in the exposed portion is consumed, no useless members are wasted.

The photopolymerizable monomers used in the present invention include (1) monomers having an acrylamide group such as acrylamide, methacrylamide, methylolacrylamide, and pyromellitic diimide; (2) acrylic acid, methyl methacrylate, and ethylene glycol. Monomers having an acryloyl group, such as unsaturated polyesters such as diacrylate, diaryl phthalate, diallyl glycolate, diallyl maleate, and diethylene glycol bisallyl carbonate; (3) monomers having a vinyl group, such as hexachlorobutadiene; 4) Monomers having an acetylene group such as methoxybutenylanthraquinone, and (5) monomers having a diacetylene group such as paratoluenesulfonylbutadiyne.

In the step of coating the photopolymerizable monomer used in the present invention on a substrate, if the photopolymerizable monomer is solid at room temperature and atmospheric pressure, the photopolymerizable monomer is dissolved in an appropriate organic solvent and printed or spun. It can be applied by an ordinary method such as a coat. Unlike the case of applying a photosensitive polymer or a polymer film, a photopolymerizable monomer is characterized by using a solvent having a low boiling point, and can greatly shorten the step of drying the organic solvent used in the application step. . If the photopolymerizable monomer is liquid at room temperature and atmospheric pressure and has low viscosity, it can be applied as it is. Further, the monomer in the unexposed portion is in a liquid state, and is easily collected and reused. When it is handled as a gaseous photopolymerizable monomer under reduced pressure, a coating step is not required at all.

The photopolymerizable monomer used in the present invention is:
Although it may be used alone, it is preferable that a photosensitizer and a polymerization initiator are contained in order to further reduce the exposure amount used for the polymerization. Examples of photosensitizers include camphorquinone, michraquinone, 2-naphthalenesulfnyl chloride,
Examples thereof include 3-methyl-2-benzoylmethylenenaphthothiazole, methylene blue, and triethanolamine. As the polymerization initiator, an organic carbonyl compound is generally used, and examples thereof include benzoin ethers such as benzoin and benzoin methyl ether, benzophenone, benzoylbenzoic acid, thioxanthone, and bornandione (camphorquinone).

As the method of irradiating the grating pattern light of the present invention, a method using a mask, a method using light interference, or an existing method for scanning in a line shape can be used. When the photopolymerizable monomer is liquid, three-dimensional stereolithography (Nikkan Kogyo Shimbun, 1990, Marutani et al.)
And a grating-like structure can be produced by computer control. The lines and spaces of the grating structure of the present invention may each be 1 μm or less, and more preferably 0.5 μm or less.

That is, according to the present invention, not only a method for forming an alignment film that does not cause contamination of a substrate or the like can be provided, but also because a photopolymerizable monomer is used as a grating forming member, it is not necessary to spend much time on forming a grating structure. The number of steps to be performed is small, and each step can be performed in a short time. In the exposure step, a small amount of exposure can be performed, and a method of manufacturing a liquid crystal display element that can reuse members can be provided.

Hereinafter, the present invention will be described in detail with reference to examples and drawings, but the present invention is not limited to these examples.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) The liquid crystal display device is TN
In drive mode, the size is 270mm (one long side) x 20
A transparent glass substrate having a thickness of 1.1 mm and a thickness of 1.1 mm and a polished surface was used. The manufacturing method will be described with reference to FIGS.

A pixel electrode 5 was formed on a glass substrate 2 serving as one upper substrate, and a grating-like alignment film 3 was further formed on the uppermost surface thereof. In this example, para-toluenesulfonylbutadiyne was used as a photopolymerizable monomer to be an alignment film, and a tetrahydrofuran solution (equivalent weight of monomer and solvent) was applied by spin coating.
The thickness of the monomer after the solvent was air-dried was about 1.0 μm. A grating-like pattern exposure was performed on this monomer film film, and a grating-like alignment film 3 was formed through a cleaning process of an unexposed portion.

The glass substrate 2 serving as the lower substrate facing the substrate is
A structure including three stripes of color filters 9 of R, G, and B and a black matrix 10 is provided. An overcoat resin 8 for flattening the surface was laminated on the color filter. Epoxy resin was used as a material for the overcoat resin. Further, a common electrode 7 was formed on the overcoat resin, and a grating-like alignment film was further formed.

Para-toluenesulfonylbutadiyne is used as a photopolymerizable monomer for forming an alignment film, a tetrahydrofuran solution (equivalent weight of monomer and solvent) is applied by spin coating, and the film thickness of the monomer after air-drying the solvent is 1.0.
It was about μm. A grating-like pattern exposure was performed on this monomer film film, and a grating-like alignment film 3 was formed through a cleaning process of an unexposed portion. The longitudinal direction of the grating-shaped groove of the present substrate is arranged to be orthogonal to the other glass substrate when the other glass substrate is overlapped.

For bonding the upper and lower substrates, an appropriate amount of polymer beads was mixed in an adhesive (epoxy resin) and printed on the substrate around the display section using a seal mask. Thereafter, the adhesive was temporarily cured, and the upper and lower substrates were combined. Then, the adhesive was cured while pressing the two substrates using a press. The adhesive is provided around the substrate and a part thereof is opened so that liquid crystal is injected.

The liquid crystal injection method is as follows. First, depressurize the panel in a vacuum system, then adhere the liquid crystal to the inlet,
The liquid crystal was injected into the panel due to a pressure difference between the inside of the panel and the vacuum system by gradually increasing the pressure in the vacuum system to normal pressure, and the injection was completed in about 2 hours. After the injection, the panel surface was pressurized in order to make the gap in the panel surface more uniform, and at the same time, the sealing port was sealed with a photocuring agent (acrylic resin). The response speed and contrast of the liquid crystal display device thus obtained were evaluated by an energization display test, and the result was almost the same as the case where a normal rubbing film was used.

In this embodiment, acrylamide, methacrylamide, methylolacrylamide, pyromellitic diimide, acrylic acid, methyl methacrylate, ethylene glycol diacrylate, diaryl phthalate are substituted for paratoluenesulfonylbutadiyne which is a photopolymerizable monomer. , Diallyl glycolate, diallyl maleate, diethylene glycol bisallyl carbonate, methoxybutenyl anthraquinone can be used.

(Embodiment 2) The liquid crystal display device is in the IPS drive mode, and its size is 270 mm (long side) × 200 mm (short side), and the display section is 10.4 inch diagonally.
A transparent glass substrate having a thickness of 1.1 mm and a polished surface was used. The manufacturing method will be described with reference to FIG.

A pixel electrode 5 was formed on a glass substrate 2 serving as one upper substrate, and a grating-like alignment film 3 was formed on the uppermost surface thereof. In this embodiment, ethylene glycol acrylate is used as a photopolymerizable monomer to be an alignment film, and a photosensitizer Michler's ketone and a polymerization initiator bornandione (camphorquinone) are used as a liquid monomer (viscosity is 3 centipoise). One hundred thirty parts by weight was added to 1 part by weight, and the mixture was applied by a spin coating method to make the monomer film thickness 1.0 μm.
m. On this monomer film, a grating-like pattern exposure was performed by light interference, the liquid monomer in the unexposed portion was collected, and a grating-like alignment film 3 was formed through a washing step.

The glass substrate 2 serving as the lower substrate facing the substrate
A structure including three stripes of color filters 9 of R, G, and B and a black matrix 10 is provided. An overcoat resin 8 for flattening the surface was laminated on the color filter. Epoxy resin was used as a material for the overcoat resin. Further, a grating-like alignment film was formed on the overcoat resin.

Ethylene glycol acrylate is employed as a photopolymerizable monomer for forming an alignment film, and a photosensitizer Michler's ketone and a polymerization initiator bornandione (camphorquinone) are added to this liquid monomer (having a viscosity of 3 centipoise). 1/300 each for parts by weight
A part by weight was added, and the mixture was applied by a spin coating method to make the monomer film thickness about 1.0 μm.

On this monomer film, a grating-like pattern exposure was performed by light interference, the liquid monomer in the unexposed portion was recovered, and a grating-like alignment film 3 was formed through a washing step. The longitudinal direction of the grating-shaped groove of the present substrate is arranged so as to be parallel when the other glass substrate is overlaid.

For bonding the upper and lower substrates, an appropriate amount of polymer beads was mixed in an adhesive (epoxy resin) and printed on the substrate around the display section using a seal mask. Thereafter, the adhesive was temporarily cured, and the upper and lower substrates were combined. Then, the adhesive was cured while pressing the two substrates using a press. The adhesive is provided around the substrate and a part thereof is opened so that liquid crystal is injected.

The liquid crystal injection method is as follows. First, depressurize the panel in a vacuum system, then adhere the liquid crystal to the inlet,
By gradually increasing the pressure in the vacuum system to normal pressure, the liquid crystal was injected into the panel due to the pressure difference between the panel and the vacuum system, and the injection was completed in about three and a half hours. After the injection, the panel surface was pressurized in order to make the gap in the panel surface more uniform, and at the same time, the sealing port was sealed with a photocuring agent (acrylic resin). The response speed and contrast of the liquid crystal display device thus obtained were evaluated by an energization display test, and the result was almost the same as the case where a normal rubbing film was used.

In this embodiment, acrylamide, methacrylamide, methylolacrylamide, pyromellitic diimide, acrylic acid, methyl methacrylate, diaryl phthalate, diallyl glycolate, diallyl are used in place of ethylene glycol acrylate as a photopolymerizable monomer. Maleate, diethylene glycol bisallyl carbonate, methoxybutenyl anthraquinone,
Paratoluenesulfonylbutadiyne can be used.

Instead of Michler's ketone as a photosensitizer, camphorquinone, Michler's quinone, 2-naphthalenesulfnyl chloride, 3-methyl-2-benzoylmethylenenaphthothiazole, methylene blue, and triethanolamine are used. Can be.

Further, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin butyl ether, benzoin, benzoin methyl ether, benzoin butyl ether,
Benzophenone, benzoylbenzoic acid, thioxanthone can be used.

(Embodiment 3) The liquid crystal display device is in a TN drive mode, and its size is 270 mm (long side) × 200 mm (short side), and the display section is 10.4 inch diagonally.
A transparent glass substrate having a thickness of 1.1 mm and a polished surface was used. The manufacturing method will be described with reference to FIGS.

A pixel electrode 5 was formed on a glass substrate 2 serving as one upper substrate, and a grating-like alignment film 3 was further formed on the uppermost surface thereof. In the present example, a gaseous monomer of hexachlorobutadiene was employed as a photopolymerizable monomer to be an alignment film. The glass substrate after the formation of the pixel electrode was placed in a reduced-pressure container in a hexachlorobutadiene atmosphere, and a grating-like pattern exposure was performed on the glass substrate to form a grating-like alignment film 3.

The glass substrate 2 serving as the lower substrate facing the substrate is
A structure including three stripes of color filters 9 of R, G, and B and a black matrix 10 is provided. An overcoat resin 8 for flattening the surface was laminated on the color filter. Epoxy resin was used as a material for the overcoat resin. Further, a common electrode 7 was formed on the overcoat resin, and a grating-like alignment film was further formed. The longitudinal direction of the grating-shaped groove of the present substrate is arranged to be orthogonal to the other glass substrate when the other glass substrate is overlapped.

For bonding the upper and lower substrates, an appropriate amount of polymer beads was mixed in an adhesive (epoxy resin) and printed on the substrate around the display section using a seal mask. Thereafter, the adhesive was temporarily cured, and the upper and lower substrates were combined. Then, the adhesive was cured while pressing the two substrates using a press. The adhesive is provided around the substrate and a part thereof is opened so that liquid crystal is injected. The liquid crystal injection method is as follows.

First, the panel is decompressed in the vacuum system, and then the liquid crystal is brought into close contact with the injection port, and the pressure in the vacuum system is gradually increased to normal pressure. The injection was completed in about 2 hours. After the injection, the panel surface was pressurized in order to make the gap in the panel surface more uniform, and at the same time, the sealing port was sealed with a photocuring agent (acrylic resin).

Using the thus obtained liquid crystal display device, the response speed and the contrast were evaluated by an energization display test, and the results were almost the same as those when a normal rubbing film was used.

In this embodiment, acrylamide, methacrylamide, methylolacrylamide, pyromellitic diimide, acrylic acid, methyl methacrylate, ethylene glycol diacrylate, diaryl phthalate, diallyl are used in place of hexachlorobutadiene which is a photopolymerizable monomer. Glycolate, diallyl maleate, diethylene glycol bisallyl carbonate, methoxybutenyl anthraquinone, paratoluenesulfonyl butadiyne can be used.

[0043]

According to the present invention, not only a method for forming an alignment film without causing contamination of a substrate or the like can be provided, but also a light-sensitive material instead of a conventional photosensitive polymer or polymer film as a grating forming member. Because polymerized monomers are used, the number of steps spent on pattern exposure in the form of a grating is small, and each step is completed in a short time. A method for manufacturing a display element can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display device in a TN drive mode for explaining the present invention.

FIG. 2 is a sectional view of a liquid crystal display device in an IPS drive mode for explaining the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polarizing plate, 2 ... Glass substrate, 3 ... Alignment film, 4 ... Liquid crystal,
5 ... pixel electrode, 6 ... spacer beads, 7 ... common electrode,
8: overcoat, 9: color filter, 10: black matrix.

Continued on the front page (72) Inventor Takumi Ueno 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Research Laboratory, Hitachi, Ltd.

Claims (3)

[Claims] 1. A method of manufacturing a liquid crystal display device in which a liquid crystal is sandwiched between a pair of glass substrates having a liquid crystal alignment film, wherein a photopolymerizable monomer on a surface of the glass substrate in contact with the liquid crystal has a grating pattern light. Forming a liquid crystal alignment film by irradiating the liquid crystal display element. 2. The method according to claim 1, wherein the photopolymerizable monomer is in a liquid state. 3. The method according to claim 1, wherein the photopolymerizable monomer is in a gaseous state.