JP2006163080A - Liquid crystal alignment film forming material and method of forming liquid crystal alignment film - Google Patents

Abstract

A liquid crystal alignment film forming material capable of forming a liquid crystal alignment film on a transparent electrode substrate by a transfer method, and a method of forming a liquid crystal alignment film on a transparent electrode substrate using the liquid crystal alignment film forming material. provide.
A material for forming a liquid crystal alignment film 10 is provided with a release layer 2 and a liquid crystal alignment film layer 3 having a concavo-convex shape on a surface in order on a support 1. On the surface of the release layer 2, for example, a groove-shaped fine uneven shape having a groove width of 10 μm or less, a groove depth of 0.5 μm or less, and a groove interval of 200 μm or less is provided. After the liquid crystal alignment film layer 3 of the liquid crystal alignment film forming material 10 is bonded to the transparent electrode substrate 20 under heating and pressure conditions, the support 1 is peeled off from the transparent electrode substrate 20 together with the release layer 2 to release the mold. The liquid crystal alignment film layer 3, which is a copy of the surface irregularities of the layer 2, is transferred onto the transparent electrode substrate 20, and the transparent electrode substrate 20 is baked as necessary to form a liquid crystal alignment film on the transparent electrode substrate 20. Form.
[Selection] Figure 1

Description

  The present invention relates to a method for forming a liquid crystal alignment film used for aligning liquid crystals in a liquid crystal display element in a predetermined direction, and a liquid crystal alignment film forming material used therefor.

In recent years, liquid crystal display elements are widely used in electronic notebooks, mobile phones, video cameras, computer displays, liquid crystal televisions, and the like. A liquid crystal display element is obtained by filling a liquid crystal composition between a pair of upper and lower glass substrates, but in order to obtain a display, a liquid crystal alignment film that aligns the liquid crystal inside the element in a predetermined direction is required. It is.
The liquid crystal alignment film is formed by flexographically printing a solution such as polyamic acid or polyimide soluble in a solvent on a glass substrate, baking it, and rubbing it in one direction with a cloth (rubbing material) such as nylon or rayon. It is common. This alignment treatment method is generally called “rubbing method”, and the alignment of liquid crystal is controlled by aligning liquid crystal molecules along fine irregularities in a certain direction.

However, in flexographic printing, since the coating film uniformity is low, the response uniformity and luminance uniformity with respect to the applied voltage are inferior, and gap defects are likely to occur due to mixing of rubbing materials and liquid crystal alignment film scraps generated during rubbing. The thin film transistor) type has a problem that the thin film transistor is likely to be deteriorated or broken down due to static electricity generated during rubbing.
In addition, those obtained by the oblique deposition method in which silicon oxide is deposited on an inclined substrate, and obtained by the photo-alignment film method in which a liquid crystal alignment film having a property of reacting to light is arranged on the substrate. Are known. However, the liquid crystal alignment film formed by the oblique deposition method or the one obtained by the photo alignment film method is advantageous for giving a predetermined pretilt angle to the liquid crystal, but the control of the pretilt angle and the uniformity of the alignment film are reduced. There was a problem that it was difficult to get. In addition, when manufacturing a liquid crystal alignment film formed by an oblique vapor deposition method, there is a problem that the mass productivity is inferior, such as vacuum vapor deposition by a high vacuum of about 10 ⁻⁵ torr.

As a method for suppressing deterioration of the quality of the liquid crystal alignment film due to dust generated during rubbing and static electricity, Japanese Patent Application Laid-Open No. 5-265004 (Patent Document 1) describes a method in which an aromatic polyester is melted to be in a liquid crystal state before coating. And a method of casting a liquid crystal solution of an aromatic polyamide. However, the liquid crystal alignment film obtained by these methods has a problem of low adhesion to the base material, and it is necessary to heat the aromatic polyester to a melting point of 300 ° C. or higher during production. In addition, there is a problem that handling property on an industrial scale is very bad, for example, it is necessary to use concentrated sulfuric acid having strong corrosiveness to dissolve the aromatic polyamide.
In addition, Japanese Patent Laid-Open No. 2002-309010 (Patent Document 2) discloses a liquid crystal alignment film in which the stretching direction of the stretched film or an orthogonal direction thereof is the alignment direction, but the film thickness is 10 to 100 μm. The applied voltage needs to be 30 V or more, and there is a problem that it cannot cope with power saving.

JP-A-5-265004 JP 2002-309010 A

  The present invention provides a liquid crystal alignment film forming material capable of forming a liquid crystal alignment film on a transparent electrode substrate by a transfer method in order to solve the problems of conventional rubbing methods such as scraping and generation of static electricity, It is another object of the present invention to provide a method for forming a liquid crystal alignment film on a transparent electrode substrate using the liquid crystal alignment film forming material.

  The present inventors use a liquid crystal alignment film forming material in which a liquid crystal alignment film layer is provided on one surface of a support via a release layer, and a groove-shaped fine uneven shape is provided on the surface of the release layer. Bonding is performed under heating and pressure conditions so that the liquid crystal alignment film layer side of the liquid crystal alignment film forming material faces the transparent electrode side of the transparent electrode substrate, and then the support of the liquid crystal alignment film forming material is peeled off together with the release layer. It was found that a liquid crystal alignment film having better performance than that of the conventional rubbing method can be formed by transferring the liquid crystal alignment film to a transparent electrode substrate and firing the transparent electrode substrate to which the liquid crystal alignment film has been transferred.

That is, according to claim 1, the above-described problem is achieved by a liquid crystal alignment film forming material comprising a release layer having a concavo-convex shape on the surface and a liquid crystal alignment film layer on the support. Achieved.
Further, according to claim 2, the above-described problem is that the surface of the release layer has a groove-shaped fine uneven shape having a groove width of 10 μm or less, a groove depth of 0.5 μm or less, and a groove interval of 200 μm or less. The liquid crystal alignment film forming material according to claim 1 is provided.
According to claim 3, the above object is achieved by the liquid crystal alignment film forming material according to claim 1 or 2, wherein a cushion layer is provided between the support and the release layer. .
Further, according to claim 4, the above-described problem is a process of bonding the liquid crystal alignment film layer of the liquid crystal alignment film forming material according to any one of claims 1 to 3 to a transparent electrode substrate under heating and pressure conditions. Then, the step of peeling the support of the liquid crystal alignment film forming material from the transparent electrode substrate together with the release layer, transferring the liquid crystal alignment film layer copied from the surface shape of the release layer to the transparent electrode substrate, and the liquid crystal alignment film layer It is achieved by a method for forming a liquid crystal alignment film, comprising a step of firing the transferred transparent electrode substrate as necessary.

  According to the present invention, a release layer is interposed between the support for the liquid crystal alignment film-forming material and the liquid crystal alignment film layer, and an uneven shape is provided on the surface of the release layer on the side in contact with the liquid crystal alignment film layer. Since the liquid crystal alignment film layer is formed by copying the surface irregularity shape of the release layer, the liquid crystal alignment film layer does not need to be directly rubbed, so the step of installing the liquid crystal alignment film on the transparent electrode substrate Can reduce the scraps and static electricity generated by the conventional rubbing method, and can prevent such scraps from being mixed in and troubles due to static electricity, and the workability can be improved because it is not necessary to clean and remove the scraps. . In addition, by using the liquid crystal alignment film forming material of the present invention, a liquid crystal alignment film layer having good liquid crystal molecular alignment can be easily provided on a transparent electrode substrate by a transfer method, so that mass production of liquid crystal elements is possible. It is effective for power saving.

In addition, the surface of the release layer is provided with a groove-shaped fine unevenness having a groove width of 10 μm or less, a groove depth of 0.5 μm or less, and a groove interval of 200 μm or less. The liquid crystal alignment film which has copied the shape has good liquid crystal molecular alignment.
In addition, the liquid crystal alignment film forming material of the present invention is provided with a cushion layer, so that when the liquid crystal alignment film layer is bonded to the transparent electrode substrate under heating and pressure, even if the surface property of the transparent electrode substrate is poor, Since it can be reliably bonded without mixing, a transparent electrode substrate with a liquid crystal alignment film can be easily produced.

Embodiments of the present invention will be described below.
As shown in FIG. 1, an embodiment of the liquid crystal alignment film forming material of the present invention has a release layer 2 on a support 1 and an orientation that can be peeled from the support 1 via the release layer 2. The film layer 3 is laminated. A fine groove-like uneven shape is provided on the surface of the release layer 2 on the side in contact with the alignment film layer 3. A method for forming a liquid crystal alignment film using the liquid crystal alignment film forming material 10 is as follows. First, the surface of the liquid crystal alignment film forming material 10 on the liquid crystal alignment film layer 3 side and the side of the transparent electrode substrate 20 to which the transparent electrode 21 is applied. The substrates are bonded together under heating and pressure conditions so that the surfaces face each other (see FIG. 2), and then the support 1 of the liquid crystal alignment film forming material 10 is peeled from the transparent electrode substrate 20 together with the release layer 2 to form a transparent electrode substrate After the liquid crystal alignment film layer 3 is transferred to 20, the transparent electrode substrate 20 to which the liquid crystal alignment film layer 3 is transferred is baked as necessary to form a liquid crystal alignment film on the transparent electrode substrate 20. A fine uneven shape is formed on the surface of the release layer 2, and therefore, the surface unevenness of the release layer 2 is also formed on the surface of the liquid crystal alignment film.

The liquid crystal alignment film forming material 10 is characterized in that a release layer 2 is interposed between the support 1 and the liquid crystal alignment film layer 3 and the surface of the release layer 2 on the side in contact with the liquid crystal alignment film layer 3 is uneven. By providing a fine concavo-convex shape having a shape, preferably a groove shape, this surface concavo-convex shape can be copied to the surface of the liquid crystal alignment film layer 3, and the liquid crystal alignment is obtained by copying the surface concavo-convex shape of the release layer 2. That is, the film layer 3 can be transferred onto the transparent electrode substrate 20. Thereby, since it is not necessary to perform a rubbing process directly on the liquid crystal alignment film layer, it is possible to prevent problems caused by scraps and static electricity generated by the rubbing method. Moreover, by using the liquid crystal alignment film forming material 10, the liquid crystal alignment film can be easily applied onto the transparent electrode substrate 20 by a transfer method.
Further, by providing the release layer 2 having a groove-like fine irregular shape formed on the surface, the liquid crystal alignment film that has copied the fine surface irregular shape has a good liquid crystal molecular orientation.
Further, the liquid crystal alignment film forming material 10 of the present invention further has a cushion layer, so that when the liquid crystal alignment film layer 3 is bonded to the transparent electrode substrate 20, even if the surface property of the transparent electrode substrate 20 is poor, the air Since it can be reliably bonded without mixing, a transparent electrode substrate with a liquid crystal alignment film can be easily produced.

Hereinafter, the present invention will be described in more detail.
First, the liquid crystal alignment film forming material of the present invention will be described.
As the support used in the liquid crystal alignment film forming material of the present invention, a resin sheet, a resin film, or the like is preferably used. Examples of resin sheets and resin films include triacetyl cellulose film, diacetyl cellulose film, acetate butyrate cellulose film, polyether sulfone film, polyacrylic resin film, polyurethane resin film, polyester film, polycarbonate film, polysulfone film, poly Ether film, trimethylpentene film, polyether ketone film, (meth) acrylonitrile film, polyethylene film, polypropylene film, polyvinyl chloride film, polystyrene film, polyethylene terephthalate film, etc. can be used, especially biaxially stretched polyethylene A terephthalate film is preferable because it is excellent in strength, heat resistance, dimensional stability, coatability, and the like.

  Although there is no restriction | limiting in particular in the thickness of a support body, About 25-150 micrometers is suitable. When the thickness of the support is less than 25 μm, the curling of the film tends to occur during drying, which is not preferable. In addition, when finished into a product form of a transfer film such as a liquid crystal alignment film forming material of the present invention, that is, a roll-like product form, if the thickness of the support exceeds 150 μm, the rigidity of the transfer film increases, Not only do roll finishing and slitting to the specified width cause the cover film to squeeze, the product weight increases and the roll cannot be finished to the specified length, and the thermal conductivity of the transfer film is inferior. There is a problem that good transfer cannot be obtained unless the transfer temperature is increased or the transfer speed is lowered during transfer to the transparent electrode substrate.

As the resin constituting the release layer of the liquid crystal alignment film-forming material of the present invention, a thermosetting resin such as melamine, alkyd, phenol, urea, urethane, isocyanate, epoxy, unsaturated polyester , Acrylic, acrylic melamine, etc., or a mixture thereof. Among them, it exhibits releasability after thermosetting, and is resistant to the solvent contained in the liquid crystal alignment layer coating liquid. What has is preferable. In addition, some thermosetting resins that do not have mold release properties can be used by compounding a silicone or fluorine mold release agent, and the mold release agent can be peeled off when the liquid crystal alignment film layer is transferred. It can also be used to adjust the force.
The surface of the release layer is provided with a concavo-convex shape, and it is particularly preferable to provide a groove-shaped fine concavo-convex shape. However, as a method of providing the groove-shaped fine concavo-convex shape, rubbing treatment or a metal bar And the like.

In the method by rubbing treatment, scraping is generated when rubbing the release layer with a rubbing roll, so cleaning is necessary at this stage, but in the subsequent transfer to the transparent electrode substrate and in the liquid crystal alignment film formation process There is no generation of waste or static electricity, and steps such as cleaning can be omitted.
In the method of forming streaks with a metal bar, fine grooves can be formed on the surface of the release layer by scraping off the solvent with the metal bar while adhering a solvent in which the release layer resin is soluble. Even when the film forming material is produced, there is no generation of scraps, which is particularly preferable. In addition, a fine groove can be attached to the surface of the release layer by applying a release layer using a metal ring bar or gravure roll wound with a wire, and any method may be used in the present invention. It is not particularly limited.
The shape of the groove is not particularly limited, but the groove width is preferably 10 μm or less, the depth is 0.5 μm or less, and the interval is 200 μm or less. If the shape of the groove is out of the above range, it may be insufficient to align the liquid crystal molecules in a certain direction. If it is within the above range, it can be arbitrarily set according to the required pretilt angle.

  For the liquid crystal alignment film layer of the liquid crystal alignment film forming material of the present invention, a resin such as polyamic acid, polyimide soluble in a solvent, polyvinyl alcohol or the like is mainly used, but by applying a solution containing these resins, drying, There is no particular limitation as long as it is a resin that cures and gives liquid crystal molecules alignment when groove-like fine irregularities are imparted to the surface. Moreover, there is no restriction | limiting in particular in the film thickness of a liquid crystal aligning film layer, However, It is preferable that it is 0.01-1 micrometer. If the film thickness of the liquid crystal alignment film layer is less than 0.01 μm, a problem in transferability tends to occur. If the film thickness exceeds 1 μm, the voltage required for driving the liquid crystal display becomes high, and power saving cannot be achieved. In addition, the liquid crystal alignment film layer contains, if necessary, auxiliary agents such as leveling agents, preservatives, colorants, ultraviolet absorbers, antioxidants, plasticizers and the like within a range that does not impair the effects of the present invention. You may let them.

  In addition, the liquid crystal alignment film forming material of the present invention has a poor surface property of the adherend when the liquid crystal alignment film layer is transferred to the transparent electrode substrate, which is the adherend, under heat and pressure. In such a case, a cushion layer can be provided as necessary. In this case, a cushion layer is provided between the support and the release layer. The thickness of the cushion layer is preferably 5 to 50 μm, although it depends on the material characteristics. If the thickness of the cushion layer of the liquid crystal alignment film forming material is less than 5 μm, it may not be possible to follow the surface shape of the transparent electrode substrate in some cases, and the step between the patterned transparent electrode and the glass substrate cannot be filled. Transfer defects may occur. On the other hand, when the thickness of the cushion layer of the liquid crystal alignment film forming material exceeds 50 μm, the cushion layer is thick and the thermal conductivity of the transfer film is poor, and the cushion layer cannot be sufficiently softened by the heat from the transfer roll during transfer. Therefore, it causes a transfer failure. In addition, when support body itself has cushioning properties, it is not necessary to newly provide a cushion layer.

As a material for such a cushion layer, a thermoplastic resin can be used. For example, a saponified product of ethylene and an acrylate copolymer, a saponified product of styrene and an acrylate copolymer, an ethylene vinyl acetate copolymer , Low density polyethylene, ethylene ethyl acrylate copolymer, styrene and isoprene, butadiene copolymer, polyester resin, polyolefin resin, acrylic resin, and the like. These resins can be used alone, mixed in an appropriate formulation, or laminated in an appropriate combination. Moreover, you may add a plasticizer as needed.
In the liquid crystal alignment film forming material of the present invention, when the liquid crystal alignment film layer has adhesiveness, a protective film can be provided on the surface as necessary. In order to make the liquid crystal alignment film forming material of the present invention into a wound product, the surface opposite to the surface provided with the liquid crystal alignment film layer of the liquid crystal alignment film forming material is subjected to a release treatment or a release treatment. It is also preferable from the viewpoint of work efficiency to bond the formed film to the liquid crystal alignment film layer after drying.

  As the protective film, a plastic film such as polyethylene terephthalate, polyethylene, polypropylene, and polyvinyl chloride, and a sheet such as paper coated with a release material such as silicone can be used. The thickness of the protective film can be 4 to 200 μm, but is preferably 15 to 50 μm from the viewpoint of workability. When the liquid crystal alignment film-forming material of the present invention is bonded to an object, this protective film is naturally removed.

In order to obtain the liquid crystal alignment film-forming material of the present invention, the release layer and the liquid crystal alignment film layer on the support are coated with a known coating such as a bar coater, roll coater, kiss coater, curtain coater, die coater, blade coater, comma coater. It can be formed by appropriately selecting and using a machine and coating the above-mentioned coating liquid for forming each layer on the support. In this case, after coating the coating liquid on the support, it can be dried using a known dryer such as an air floating dryer or an infrared dryer. In addition, after coating the said release layer, a suitable groove-shaped fine uneven | corrugated shape is formed in the surface of a release layer using the above-mentioned method.
In addition, when a cushion layer is provided between the support and the release layer, the cushion layer coating liquid can be formed on the support using the known coating machine. Alternatively, the cushion layer resin can be melted and coextruded with the support.
Moreover, the protective film for protecting the said liquid crystal aligning film layer can be provided by bonding on a liquid crystal aligning film layer on suitable bonding conditions (temperature, pressure).

Next, a method for forming a liquid crystal alignment film using the liquid crystal alignment film forming material as described above will be described. The method for forming a liquid crystal alignment film using the liquid crystal alignment film forming material of the present invention is as follows. 1) The liquid crystal alignment film forming material has a suitable surface on the liquid crystal alignment film layer side and the transparent electrode substrate provided with the transparent electrode. Steps for bonding under heating and pressure conditions 2) Next, the support for the liquid crystal alignment film forming material is peeled off from the transparent electrode substrate together with the release layer (with cushion layer and release layer if having a cushion layer), A liquid crystal alignment film is formed on the transparent electrode substrate by a step of transferring the liquid crystal alignment film layer onto the transparent electrode substrate and 3) a step of firing the transparent electrode substrate thus transferred with the liquid crystal alignment film layer as necessary.
Specifically, for example, by setting a sheet of a rolled-up liquid crystal alignment film forming material on a laminator and peeling off the protective film, it is bonded to a transparent electrode substrate, and then the support is peeled off. A liquid crystal alignment film is formed on the transparent electrode substrate, and a transparent electrode substrate with a liquid crystal alignment film is obtained. Here, the roll temperature, pressure, and speed of the laminator are appropriately set so as to satisfy appropriate conditions. As a laminator to be used, a general laminator used for laminating a dry film can be used, and continuous laminating can be performed if a protective film winding device is incorporated. In this case, if a carrier film is used, it can work efficiently without making the laminator roll dirty.
If necessary, after the liquid crystal alignment film forming material is transferred onto the transparent electrode substrate as described above, a baking treatment is performed to form the liquid crystal alignment film. Although it varies depending on the resin used for the liquid crystal alignment film forming material, it is usually sufficient to perform the baking treatment at a temperature of 50 ° C. to 400 ° C. for 30 minutes to 5 hours.

  A transparent electrode substrate with a liquid crystal alignment film manufactured by forming a liquid crystal alignment film on a transparent electrode substrate using the liquid crystal alignment film forming material of the present invention is further processed into a liquid crystal cell, and various liquid crystal display devices, for example, Used in electronic notebooks, mobile phones, video cameras, computer displays, liquid crystal televisions, etc.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the examples and comparative examples, “parts” represents “parts by weight” unless otherwise specified.
[Example 1]
Using polyethylene terephthalate with a film thickness of 38μm as a support, the following release layer coating solution is made 20% solids, coated on the support with a # 20 Meyer bar, dried at 80 ° C for 1 minute, and the film thickness A release layer of 6 μm was obtained.
Next, a rubbing process is performed on the release layer using a rubbing apparatus RM-50 (manufactured by EHC) under conditions of a table speed of 1200 rpm, a roll speed of 300 rpm, and one reciprocation, and the width is 3 μm, the depth is 0.1 μm, and the interval is 40 μm. Groove-shaped fine irregularities were provided. At this time, since scraps and static electricity were generated, they were removed by washing. Thereafter, the release layer was thermally cured at 140 ° C. for 2 minutes.
The following liquid crystal alignment film layer coating solution having a solid content of 2% was applied on the release layer with a # 8 Meyer bar and dried at 80 ° C. for 1 minute to form a liquid crystal alignment film layer having a thickness of 0.3 μm. .
<Release layer coating solution>
Tesfine 324
(Acrylic copolymer, product name manufactured by Hitachi Chemical Co., Ltd.) 100 parts Dryer 900
(Paratoluenesulfonic acid, product name manufactured by Hitachi Chemical Polymer Co., Ltd.) 4 parts Ethyl acetate 50 parts Butyl cellosolve 50 parts <Liquid crystal alignment layer coating solution>
Sunever SE-130 (Polyimide varnish, trade name manufactured by Nissan Chemical Industries, Ltd.) 100 parts

Thus, a liquid crystal alignment film forming material of this example was obtained.
Next, after placing a transparent electrode substrate having a patterned transparent electrode on a hot plate at 60 ° C. and preheating, as shown in FIG. 2, the alignment of the obtained liquid crystal alignment film forming material of this example is performed. The film layer side and the transparent electrode side of the transparent electrode substrate were bonded using a laminator (VA-900) manufactured by Taisei Laminator Co., Ltd. The bonding conditions at this time were a roll temperature of 120 ° C., a roll speed of 0.8 m / min, and a pressure of 0.5 MPa.
Subsequently, the support for the liquid crystal alignment film forming material is peeled off together with the release layer, and after the liquid crystal alignment film is transferred to the transparent electrode substrate, baking is performed at 200 ° C. for 2 hours, and the polyimide electrode is formed on the transparent electrode substrate A liquid crystal alignment film was formed. The surface of the liquid crystal alignment film was formed by copying the fine groove-like irregularities on the surface of the release layer.

A pair of transparent electrode substrates with a liquid crystal alignment film thus obtained was assembled with a 5 μm spacer interposed therebetween in anti-parallel to the rubbing direction, and liquid crystal (Merck: ZLI-2293) was injected to prepare a liquid crystal cell.
When this liquid crystal cell was rotated in crossed Nicol, clear light and darkness was recognized, and it was confirmed that the liquid crystal molecules were well aligned in the rubbing direction.
In addition, a polarizing plate is attached to both surfaces of the liquid crystal cell so that the polarization planes (polarization directions) are orthogonal to each other, and a voltage of 12 V and 64 Hz is used using a liquid crystal display device (STN type liquid crystal display element) manufactured by EACH Co., Ltd. As a result of visual evaluation of black display density unevenness, uniform display was obtained without unevenness.
[Example 2]

An aluminum rod having a length of 30 cm and a thickness of 1 cm was polished with sandpaper # 2000 while rotating around the long axis to obtain a grooved aluminum rod. The grooved aluminum rod was formed with fine groove-like irregularities with a period of about 8 μm and a depth of about 2 μm.
In the same manner as in Example 1, a release layer was applied on the support, dried, and then the surface of the release layer was scratched by immersing the surface of the release layer with ethyl acetate using this grooved aluminum rod. The width of the release layer was 7 μm. This was prepared in the same manner as in Example 1 except that after forming groove-shaped fine irregularities with a depth of 0.1 μm and an interval of 160 μm, thermosetting was performed at 140 ° C. for 2 minutes. In this example, when the concave and convex shapes were provided on the release layer, there was no generation of scraps or static electricity.
Next, in the same manner as in Example 1, a liquid crystal alignment film layer was formed on the release layer to produce a liquid crystal alignment film forming material of this example.

Using this liquid crystal alignment film forming material, a transparent electrode substrate with a liquid crystal alignment film in which a liquid crystal alignment film was formed was produced in the same manner as in Example 1. Using this transparent electrode substrate with a liquid crystal alignment film, a liquid crystal cell was produced in the same manner as in Example 1. When this liquid crystal cell was rotated in crossed Nicol, clear light and darkness was observed, and the direction rubbed with a grooved aluminum rod It was confirmed that the liquid crystal molecules were well aligned.
In addition, when polarizing plates were attached to both surfaces of the liquid crystal cell so that the polarization planes were orthogonal to each other and a voltage was applied using the same liquid crystal display device as in Example 1, a uniform display was obtained without uneven density of black display. It was.

[Comparative example]
The liquid crystal alignment film coating solution of Example 1 was applied on the transparent electrode substrate with a spin coater under conditions of 500 rpm and 10 seconds, and dried at 80 ° C. for 1 minute to a film thickness of 0.3 μm. After firing at 200 ° C for 2 hours, the liquid crystal alignment film layer was rubbed using a rubbing machine RM-50 (EHC) at a table speed of 1200 rpm, a roll speed of 500 rpm, and 5 reciprocations. Groove-shaped fine irregularities having a thickness of 0.1 μm and an interval of 35 μm were provided. At this time, generation of scraps and static electricity was severe, and these were removed.
A pair of transparent electrode substrates with a liquid crystal alignment film thus obtained was assembled with a rubbing direction antiparallel across a 5 μm spacer, and liquid crystal (Merck: ZLI-2293) was injected to produce a liquid crystal cell.
When this liquid crystal cell was rotated in crossed Nicol, clear light and darkness was recognized, and it was confirmed that the liquid crystal molecules were well aligned in the rubbing direction.
In addition, when polarizing plates were attached to both surfaces of the liquid crystal cell so that the polarization planes were orthogonal to each other and a voltage was applied using the same liquid crystal display device as in Example 1, there was no uneven density and a uniform display was obtained. It was. However, although the rubbing material generated during rubbing of the liquid crystal alignment film layer and the shaving residue of the liquid crystal alignment film have been removed for the time being, the thin film transistor deteriorates due to gap defects due to the mixing of the shaving residue, especially in the TFT type due to static electricity generated during rubbing. Or dielectric breakdown may occur.

[Reference example]
An aluminum rod with a length of 30 cm and a thickness of 1 cm is polished with a # 500 sandpaper while rotating around the long axis to obtain a grooved aluminum rod. The surface of the release layer is acetic acid using this grooved aluminum rod. A release layer was formed on the support in the same manner as in Example 2 except that it was scratched while being soaked in ethyl. At this time, the grooved aluminum rod has groove-shaped irregularities with a period of about 20 μm and a depth of about 5 μm, and the surface of the release layer has groove-shaped irregularities with a width of 20 μm, a depth of 0.5 μm, and an interval of 320 μm. Was formed.
Next, in the same manner as in Example 1, a liquid crystal alignment film layer was formed on the release layer to produce a liquid crystal alignment film forming material.
Using this liquid crystal alignment film forming material, a transparent electrode substrate with a liquid crystal alignment film in which a liquid crystal alignment film was formed was produced in the same manner as in Example 1. Using this transparent electrode substrate with a liquid crystal alignment film, a liquid crystal cell was produced in the same manner as in Example 1. When this liquid crystal cell was rotated in crossed Nicol, the difference in brightness was not clear, and it was rubbed with a grooved aluminum rod. The alignment of the liquid crystal molecules in the direction was not sufficient.
When polarizing plates were attached to both surfaces of the liquid crystal cell so that the polarization planes were orthogonal to each other and a voltage was applied using the same liquid crystal display device as in Example 1, there was no particular unevenness in density and almost uniform display was obtained. It was.
The evaluation results in the above Examples, Comparative Examples, and Reference Examples are summarized in Table 1 below.

The evaluation criteria in the table are as follows.
-Uniformity during voltage application: Using the liquid crystal display device described above, a predetermined voltage was applied, and density unevenness in black display was visually evaluated.
(○: There is no unevenness and there is no problem in practical use. △: Some unevenness is conspicuous ×: Unevenness is severely unsuitable for practical use)
-Orientation: The liquid crystal cell was rotated in crossed Nicols, and the difference in brightness was evaluated.
(○: The difference between light and dark is clear and the alignment of liquid crystal molecules is sufficient ×: The difference between light and dark is not clear and the alignment of liquid crystal molecules is insufficient)
-Generation of shavings and static electricity: The amount of shavings and static electricity (hereinafter referred to as scum) generated when forming a liquid crystal alignment film on a transparent electrode substrate was evaluated.
(○: No debris or the like is generated. Δ: Debris or the like is slightly generated, but a small amount compared to the conventional rubbing method. X: Large amount of debris or the like is generated.)
As shown in Table 1 above, it can be seen that only the examples of the present invention satisfy all the evaluation items for the occurrence of uniformity, orientation, residue, etc. during voltage application.
In the above embodiments, the STN type is used as the liquid crystal display element. However, the liquid crystal display element is not limited to this, but is a TN type having a twist angle of 90 degrees, and an electric field birefringence type liquid crystal display element having no twist angle. Needless to say, the same effect can be obtained with a ferroelectric liquid crystal display element.

It is sectional drawing which shows the structure of one Embodiment of the liquid crystal aligning film forming material of this invention. It is sectional drawing of the state which bonds the liquid crystal aligning film forming material of one Embodiment to a transparent electrode substrate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 Release layer 3 Liquid crystal aligning film layer 10 Liquid crystal aligning film forming material 20 Transparent electrode substrate 21 Transparent electrode

Claims (4)

  A liquid crystal alignment film forming material comprising a release layer and a liquid crystal alignment film layer each having a concavo-convex shape on a surface in order on a support.   2. The liquid crystal according to claim 1, wherein the surface of the release layer is provided with a groove-shaped fine uneven shape having a groove width of 10 μm or less, a groove depth of 0.5 μm or less, and a groove interval of 200 μm or less. Alignment film forming material.   The liquid crystal alignment film forming material according to claim 1, wherein a cushion layer is provided between the support and the release layer.   A step of bonding the liquid crystal alignment film layer of the liquid crystal alignment film forming material according to any one of claims 1 to 3 to the transparent electrode substrate under heating and pressure conditions, and thereafter releasing the support of the liquid crystal alignment film forming material The step of transferring the liquid crystal alignment film layer, which is peeled off from the transparent electrode substrate together with the layer and copying the surface shape of the release layer, to the transparent electrode substrate, and the baking process is performed on the transparent electrode substrate to which the liquid crystal alignment film layer has been transferred A method for forming a liquid crystal alignment film.

Images