JP3264477B2 - Liquid crystal alignment film, method for manufacturing liquid crystal alignment film, liquid crystal display device, and method for manufacturing liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device using a liquid crystal and a method of manufacturing the same, and more particularly, to a liquid crystal alignment film used for a flat display panel using a liquid crystal for displaying a TV image, a computer image, and the like. And a method of manufacturing the same, a liquid crystal display device using the same, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, in a color liquid crystal display panel, a film formed by applying and firing a polyvinyl alcohol or a polyimide with a spinner between two substrates having opposed electrodes arranged in a matrix is rubbed with a felt cloth. That is, a device in which liquid crystal was sealed through a liquid crystal alignment film produced by rubbing was generally used.

[0003]

However, as described above, a conventional orientation film is formed by dissolving polyvinyl alcohol or polyimide in an organic solvent, applying the solution using a spin coating method or the like, and then applying a felt cloth or the like. The rubbing method has been used, so that it is difficult to uniformly coat the alignment film on a large-area panel (for example, a 14-inch display). Such a display panel that requires an alignment film having a thickness of about 1000 angstroms has a great disadvantage that the performance is greatly reduced.

Recently, a method of providing a rubbing-free alignment film by exposing a polarizing film to a mask using a polyvinyl cinnamate or polyimide film has been developed. However, the exposure time was extremely low at several J / cm ² , and the time required for exposure took several minutes, which was not practical.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a highly reliable alignment film which does not require rubbing as in the prior art, and a method for forming it with high efficiency in a short time. Another object is to provide a display panel using the same and a method for manufacturing the same.

[0006]

Means for Solving the Problems The liquid crystal alignment film of the present invention comprises:
In order to achieve the above-mentioned object, a monomer containing an energy beam-sensitive group and a heat-reactive group is copolymerized.
Engaged the a resin and a transparent resin film in the visible light region is formed indirectly via a direct or any thin film on the electrode, characterized in that it is reacted crosslinking at least the energy beam sensitive radical .

Further, the method for producing a liquid crystal alignment film according to the present invention comprises:
Resin copolymerized from a monomer containing an energy beam-sensitive group and a heat-reactive group, respectively , directly or indirectly through a thin film on a predetermined substrate surface on which electrodes are formed
A step becomes and the transparent resin film in the visible light region coating formed from, characterized by a step of reacting the crosslinking energy beam sensitive radical by irradiating an energy beam to the resin film via at least any of the mask And

With the above structure, a rubbing step, which has conventionally had a very high rate of occurrence of defects, becomes unnecessary, and a display panel using the rubbing step can be manufactured at extremely low cost.

Further, the liquid crystal display device of the present invention comprises a monomer having an energy beam-sensitive group and a heat-reactive group.
A liquid crystal alignment film composed of a resin copolymerized from and having a transparent resin film in the visible light region formed directly or indirectly through an optional thin film on the electrode, and having at least an energy beam-sensitive group reactively crosslinked. and characterized in that but is formed on at least one of the electrodes of the two opposing electrodes is sandwiched through the resin film to the electrodes the liquid crystal is two opposing
I do .

Further, according to the method of manufacturing a liquid crystal display device of the present invention, the energy beam sensitivity can be directly or indirectly applied via a thin film on a first substrate having a first electrode group mounted in a matrix. Groups and thermoreactive groups, respectively.
Coating and forming a transparent resin film made of a resin copolymerized from a monomer in the visible light range, and irradiating an energy beam through at least any mask to react and crosslink the energy beam sensitive group. A step of aligning and bonding and fixing a second electrode or a second substrate having an electrode group placed so as to face the first electrode group so that the respective electrode sides face each other; Injecting a predetermined liquid crystal into the second substrate .
You .

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An alignment film according to an embodiment of the present invention will be described below.

Therefore, first, the outline of the alignment film in the present embodiment will be described. First, a transparent resin film in the visible light region having an energy beam sensitive group and a thermally reactive group is applied and formed directly or indirectly through an arbitrary thin film on a predetermined substrate surface on which electrodes are formed. Next, an energy beam is irradiated through an arbitrary mask to react-crosslink the energy beam-sensitive group.

At this time, the energy beam-sensitive group is a photosensitive group, and is irradiated with light through a mask to react the photosensitive group in the coating, cross-link between main chains and orient side groups. If the fixing step is used, a conventional exposure machine can be used without the need for rubbing as in the conventional case, and the manufacturing process of the liquid crystal alignment film can be simplified.

Further, when exposure was performed through a polarizing film or a diffraction grating as a mask, a liquid crystal alignment film having streaky irregularities on the surface could be manufactured with high efficiency.

At this time, exposure is performed obliquely through a polarizing film and a diffraction grating, or exposure is performed obliquely through a diffraction grating after exposure through a polarizing film, or exposure is performed through a diffraction grating. A liquid crystal alignment film that can control the pretilt angle of the interposed liquid crystal by obliquely exposing through the film was manufactured. In the step of exposing through a diffraction grating, it was important to perform exposure until the surface of the photosensitive film became uneven to stabilize the orientation.

Further, when the heat-reactive group is reacted by heating before or after the step of irradiating the energy beam with the energy beam to react and crosslink the energy beam-sensitive group, the alignment heat resistance of the liquid crystal is improved. Electron beams, X-rays, or ultraviolet rays can be used as energy beams, but ultraviolet rays have been more practical.

When a substance represented by the following chemical formula is used as a transparent resin in the visible light region having an energy beam-sensitive group and a heat-reactive group, the liquid crystal has a high ultraviolet sensitivity and can utilize a thermal crosslinking reaction. It was very convenient for producing an alignment film.

[0018]

Embedded image

In the chemical formula (2), an energy beam-sensitive benzalacetophenone group and a thermally reactive glycidyl group are introduced as a side chain group, and a hydrocarbon group (--CH ₃ ) is further added to the side chain group. As a result, the alignment stability was further improved as compared with those not containing a hydrocarbon group as a side chain group. Further, in this case, it is important to improve the alignment stability of the liquid crystal by exposing the transparent resin film until the surface of the transparent resin film becomes streaky unevenness of 1 to 100 nm.

According to the method described above, a transparent resin film in the visible light region having an energy beam sensitive group and a thermally reactive group is formed directly on the electrode or indirectly through an arbitrary thin film. A rubbing-free liquid crystal alignment film composed of a film reacted with an energy beam-sensitive group could be manufactured by an extremely simple method.

Therefore, in the actual manufacture of a display element, the energy beam sensitive substrate is directly or indirectly connected via a thin film on a first substrate having a first electrode group previously mounted in a matrix. A step of applying and forming a transparent resin film in a visible light region having a heat-reactive group, and a step of irradiating an energy beam through at least an arbitrary mask to react and cross-link the energy beam-sensitive group,
Positioning a second substrate having a second electrode or an electrode group placed so as to face the first electrode group so that the respective electrode sides face each other; Using a step of injecting a predetermined liquid crystal into the first and second substrates, a transparent resin film in the visible light region having an energy beam sensitive group and a thermally reactive group is applied and formed, and at least through an arbitrary mask A film formed by irradiating an energy beam to react and crosslink the energy beam-sensitive group is formed on at least one of two opposing electrodes as an alignment film for liquid crystal, and the liquid crystal is exposed to the two opposing electrodes. A liquid crystal display device having a structure sandwiched between the electrodes with the film interposed therebetween could be manufactured with extremely high efficiency.

Next, a liquid crystal alignment film according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a manufacturing process of a liquid crystal alignment film according to an embodiment of the present invention. Hereinafter, the present embodiment will be described with reference to FIGS. 1 (a) to 1 (d). It shall be.

First, 4 ′ methacryloyloxy chalcone (4 ′ MC) and glycidyl methacrylate (GMA) were previously copolymerized in a molar ratio of 1: 4 to obtain a photosensitive compound represented by the following chemical formula (2). A transparent resin (that is, a resin having an energy beam-sensitive group and a heat-reactive group) in the visible light region in which a glycidyl group and a methyl group capable of being thermally cross-linked with a benzalacetophenone group are introduced as a side group, The solution was diluted to 0.5% with cyclohexanone to prepare a photosensitive solution.

Next, as shown in FIG. 1A, a predetermined glass substrate 2 on which a transparent electrode 1 made of ITO is previously formed is directly (or through an insulating thin film such as SiO _2). Or indirectly) using a dipping method (or a roll coater or a flexographic printing method may be used) to apply the above-mentioned photosensitive solution to form a photosensitive and thermosetting film as shown in FIG. 1 (b). 3 was formed.

Thereafter, the mixture was heated at 100 ° C. for 10 minutes to evaporate and remove most of the solvent (at this time, the film thickness was about 30 minutes).
0 nm). Next, as shown in FIG.
The electrode pattern and the grating are parallel to each other using a diffraction grating 4 of 000 lines / mm (a polarizing plate may be used, but in that case, the exposure time needs to be increased because the light transmittance is low). With a 500 W ultra-high pressure mercury lamp as an energy beam from the vertical direction at 365 nm
Ultraviolet light 5 of wavelength (i-line) (28 mJ / c after passing through mask)
m ² ) for 5 seconds to react and crosslink the photosensitive benzal acetophenone group, and the coating surface has a pitch of 1000 / mm along the diffraction grating pattern at a pitch of about 1000 / mm.
The unevenness of 0 nm was formed.

FIG. 2 shows the spectral sensitivity characteristics of the photosensitive film at this time. In this state, a liquid crystal display cell is assembled with a 20 micron gap, and a nematic liquid crystal (ZLI4792;
(Merck Co., Ltd.) was injected to confirm the orientation state, and it was confirmed that the liquid crystal was oriented in a direction crossing the diffraction grating pattern. It was also confirmed that the pretilt angle of the injected liquid crystal could be controlled according to the exposure amount.

On the other hand, in the above-mentioned exposure step, after exposing for 3 seconds using a diffraction grating, a commercially available UV polarizing plate 6 (HNP'B; manufactured by Polaroid) is used as a mask, and the diffraction grating pattern and polarization Using a 500 W ultra-high pressure mercury lamp as an energy beam, the direction was set so that the direction was perpendicular and the incident angle was 45 degrees with respect to the substrate.
UV light with a wavelength of 65 nm (i-line) (3 mJ after passing through the mask)
/ Cm ² ) for 40 seconds (FIG. 1 (d)), and the unreacted residue of the energy beam-sensitive group was further reacted and cross-linked.

In this state, the liquid crystal display cell was assembled, nematic liquid crystal was injected, and the alignment state was confirmed. It was confirmed that the liquid crystal was oriented in the direction of the lattice pattern and the pretilt angle was about 20 degrees. Was. It was also confirmed that the pretilt angle of the injected liquid crystal could be controlled by changing the irradiation angle in the second irradiation. In addition,
Although the alignment films produced by the above two processes could be used as alignment films as they were, heat treatment at about 150 ° C. deteriorated the alignment properties of the alignment films.

Then, in order to further improve the thermal stability of the alignment film, the alignment layer was heated at 180 ° C. for 10 minutes to ring-open and crosslink the thermally reactive glycidyl group (ie, thermosetting group). In this state, the liquid crystal display cell was assembled, nematic liquid crystal was injected, and the alignment state was confirmed. The liquid crystal was aligned in a direction perpendicular to the lattice pattern, and the pretilt angle was about 7 degrees. Further, the thermal stability of the alignment film was improved to 170 ° C.

The reaction by exposure of the photosensitive and thermosetting coating and the reaction by heating at this time are both crosslinking reactions as shown in the following reaction formula.

[0032]

Embedded image

Further, the same experiment was attempted by synthesizing a compound containing no hydrocarbon group (-CH ₃ ), but the alignment controllability of the liquid crystal, especially the pretilt angle control stability, was worse than that containing -CH _3. Was.

As described above, in the coating of the present embodiment,
The energy beam-sensitive group is a photosensitive group, and reacts with the photosensitive group in the coating by irradiating light through a mask,
Cross-linking between the main chains and the orientation of the side chain groups could be fixed. In addition, since there is sensitivity to i-line (see FIG. 2), a normal exposure machine can be used, and the manufacturing process of the liquid crystal alignment film can be simplified.

Further, by exposing through a polarizing film or a diffraction grating as a mask, a liquid crystal alignment film having streaky irregularities on the film surface could be easily produced.

Further, at this time, the amount of exposure, or the oblique exposure through the polarizing film and the diffraction grating, the oblique exposure through the polarizing film and then the exposure through the diffraction grating, or the exposure through the diffraction grating By performing the oblique exposure after the exposure through the polarizing film, the pretilt angle of the sandwiched liquid crystal could be controlled, and a liquid crystal alignment film having stable alignment could be manufactured. In order to stably control the pretilt angle in a single exposure, it was important to perform exposure until the surface of the photosensitive film became a predetermined unevenness.

Further, when the heat-reactive group is reacted by heating before or after the step of irradiating the energy beam with the energy beam-sensitive group to react and crosslink the energy beam-sensitive group, the alignment film has improved alignment heat resistance. In addition, electron beams, X-rays, or ultraviolet rays can be used as energy beams, but ultraviolet rays were more practical in actual manufacturing processes.

As described above, a transparent resin film in the visible light region having an energy beam sensitive group and a thermally reactive group is formed directly on the electrode or indirectly through an arbitrary thin film. A rubbing-free liquid crystal alignment film composed of a film having a sensitive group reacted was produced by an extremely simple method.

Next, a liquid crystal display device using the above liquid crystal alignment film and a method for manufacturing the same will be described in detail with reference to FIG.

First, a photosensitive liquid was prepared by previously diluting a transparent resin in the visible light region having an energy beam-sensitive group and a heat-reactive group represented by (Chemical Formula 2) to 0.5% with cyclohexanone. As shown in FIG. 3, on a first substrate 13 having a first electrode group 11 mounted in a matrix and a transistor group 12 for driving the electrodes, and facing the first electrode group. A photosensitive and thermosetting resin film was formed on both electrodes on the second substrate 16 having the mounted color filter group 14 and the second electrode 15 by dipping.

After heating at 100 ° C. for 10 minutes to remove a certain amount of the solvent, the electrode pattern and the grating were set in parallel using a 1000 / mm diffraction grating as a mask. As 50
Ultraviolet light of a wavelength of 365 nm (i-line) (28 mJ / cm ² after passing through a mask) was irradiated for 5 seconds using an ultrahigh pressure mercury lamp of 0 W for 5 seconds to react and crosslink the energy beam-sensitive benzalacetophenone group. Thus, a liquid crystal alignment film 17 having irregularities of about 30 to 40 nm was formed.

Next, the first and second substrates 13 and 16 were aligned so as to oppose each other, and were fixed with a spacer 18 and an adhesive 19 with a gap of about 5 μm. Then, after injecting the liquid crystal 20 into the first and second substrates, the display device was completed by combining the polarizing plates 21 and 22.

In such a device, an image can be displayed in the direction of arrow A by driving each transistor using a video signal while irradiating the backlight 23 over the entire surface.

[0044]

As described above, the liquid crystal alignment film of the present invention can be directly or indirectly indirectly through an arbitrary thin film on the surface of a predetermined substrate on which an electrode is formed. A step of applying and forming a transparent resin film in a visible light region having a group, and a step of irradiating an energy beam through at least an arbitrary mask to react and crosslink the energy beam-sensitive group; Thus, a uniform and extremely thin alignment film can be produced.

Further, by using such a liquid crystal alignment film, it is possible to provide a liquid crystal display device having a high yield, extremely low cost and high reliability without requiring a rubbing step as in the conventional case.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of a liquid crystal alignment film according to an embodiment of the present invention.

FIG. 2 is a diagram showing spectral sensitivity characteristics of a photosensitive and thermosetting resin in a liquid crystal alignment film according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view of the liquid crystal display device according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 electrode 2 glass plate 3 photosensitive and thermosetting resin film 4 diffraction grating mask 5 ultraviolet light 6 polarizing plate mask 11 first electrode group 12 transistor group 13 first substrate 14 color filter group 15 second electrode 16 Second substrate 17 Rubbing-free liquid crystal alignment film 18 Spacer 19 Adhesive 20 Liquid crystal 21, 22 Polarizing plate 23 Backlight

Claims (13)

(57) [Claims] 1. A resin copolymerized from a monomer containing an energy beam sensitive group and a thermoreactive group, respectively.
And transparent resin film in the visible light region is formed indirectly via a direct or any thin film on the electrode, a liquid crystal alignment film, which has been reacted crosslinking at least the energy beam sensitive radical. 2. The liquid crystal alignment film according to claim 1, wherein an energy beam sensitive group and a heat reactive group are introduced as a side chain group in the resin film. 3. The liquid crystal alignment film according to claim 1, wherein an energy beam sensitive group, a heat reactive group, and a hydrocarbon group are introduced as a side chain group in the resin film. 4. The liquid crystal alignment film according to claim 1, wherein the surface of the resin film is formed with streaks. 5. The liquid crystal alignment film according to claim 1, wherein the thermoreactive group is reactively crosslinked. 6. The liquid crystal alignment film according to claim 1, wherein a substance represented by the following chemical formula is used as the resin film. Embedded image 7. Copolymerization of a monomer containing an energy beam sensitive group and a heat reactive group, respectively , directly or indirectly through a thin film on a predetermined substrate surface on which an electrode is formed.
A step of applying and forming a resin film made of a combined resin and transparent in the visible light range, and a step of irradiating the resin film with an energy beam through at least an arbitrary mask to react and crosslink the energy beam-sensitive group. A method for producing a liquid crystal alignment film comprising: 8. The method for producing a liquid crystal alignment film according to claim 7, wherein a step of reacting and crosslinking the heat reactive group by heating is added before or after the step of reacting and crosslinking the energy beam sensitive group. 9. The energy beam-sensitive group is a photosensitive group, and is irradiated with ultraviolet rays through a mask to react the photosensitive group in the resin film, thereby to crosslink between main chains and to fix side chain groups. The method for producing a liquid crystal alignment film according to claim 7, wherein: 10. The method according to claim 7, wherein the exposure is performed using a polarizing film or a diffraction grating as a mask. 11. The method according to claim 7, wherein the exposure is performed until the surface of the resin film becomes uneven. 12. A resin copolymerized from a monomer containing an energy beam-sensitive group and a thermo-reactive group.
In addition , a resin film transparent in the visible light region is formed directly on the electrode or indirectly via an arbitrary thin film, and at least the liquid crystal alignment film reactively cross-linked to the energy beam-sensitive group is formed on two opposite electrodes. Wherein the liquid crystal is interposed between the two opposing electrodes via the resin film. 13. An energy beam-sensitive group and a heat-reactive group are directly or indirectly applied via a thin film on a first substrate having a first electrode group placed in a matrix.
Consists of a resin copolymerized from the monomers contained in each
One the step of the transparent resin film in the visible light region is formed by coating, a step of reacting crosslink by irradiation the energy beam sensitive radical energy beam via at least any of the mask, facing the first electrode group Bonding and fixing a second substrate having a second electrode or an electrode group mounted thereon such that the respective electrode sides face each other;
Injecting a predetermined liquid crystal into the first and second substrates.