JPH032830A - Production of oriented film for liquid crystal - Google Patents

Abstract

PURPOSE:To easily obtain the oriented film for liquid crystal molecules consisting of a high polymer resin by maintaining a substrate having a resin layer at a specific temp. and rubbing the surface of the resin layer with fibers. CONSTITUTION:The liquid crystal molecules at the boundary of an instrument wall are required to be oriented in order to orient the liquid crystal molecules. The oriented film is, therefore, provided usually on the boundary face. The surface of the oriented film requires some order and this order interacts with the liquid crystal molecules to orient the liquid crystal molecules at the boundary of the instrument wall. Such order is induced by stretching the high polymer of the oriented film in one way. The way of the stretching of the oriented film molecules varies with the substrate temp. at the time of the rubbing. Namely, the substrate 2 having the resin layer is kept at about <=50 deg.C and the surface of the resin layer is rubbed by the fibers 4, etc. The substrate having the resin layer is kept at about <=0 deg.C and the surface of the resin layer is rubbed by the fibers 4. The resin film for orienting the liquid crystal molecules is easily obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for producing an alignment film for liquid crystal molecules made of a polymer resin.

BACKGROUND OF THE INVENTION A liquid crystal molecule alignment film is essential for liquid crystal displays.

As the alignment film, an R-free obliquely evaporated film, a rubbed organic resin film, or the like is used (Basics and Applications of Liquid Crystal Electronics, edited by Akio Sasaki).

Problems to be Solved by the Invention However, the problem with obliquely deposited inorganic films is that the equipment is relatively expensive and the process cost is high because it is a vacuum process.

Generally, rubbing methods are often used in industry, but in a mode in which liquid crystal molecules have a large twist angle, that is, a super twisted nematic mode, uniform rubbing pressure and high density rubbing are required. Strict management is required to achieve this condition.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention maintains a substrate having a resin layer at a temperature of about 50°C or higher, and then rubs the surface of the resin layer with fibers or the like. The present invention provides a method for producing an alignment film for liquid crystal.

The present invention also provides a method for producing an alignment film for a liquid crystal, in which a substrate having a resin layer is kept at a temperature of about 0° C. or less, and the surface of the resin layer is rubbed with a fiber or the like.

The present invention further provides that when the entire surface of a substrate having a resin layer is rubbed with fibers or the like, a linear contact portion between the fibers and the substrate is temporally scanned over the entire surface of the substrate; The present invention also provides a method for producing an alignment film for liquid crystal, characterized in that a portion of the substrate immediately after contact is irradiated with infrared rays for a predetermined period of time.

Further, in the present invention, it is desirable that the fibers are rotated with respect to the substrate surface.

In order to align the working liquid crystal molecules, it is necessary to align the liquid crystal molecules at the vessel wall interface. For this purpose, an alignment film is usually provided at the interface. It is understood that a certain order is required on the surface of the alignment film. This order interacts with the liquid crystal molecules and orients them at the vessel wall interface. Such order is caused by stretching the polymer of the alignment film in one direction by rubbing.

It is understood that the manner in which the molecules of the alignment film are stretched differs depending on the substrate temperature during rubbing. When the temperature of the substrate or resin layer is higher than room temperature, the degree of stretching of the alignment film molecules increases, and if a suitable alignment film material is selected, super twisted nematic mode is generally preferred. It seems that once a large pretilt angle is obtained, the influence of electrostatic charging during rubbing becomes smaller as a result of a decrease in the resistance value of the resin layer.

When the substrate temperature or the temperature of the resin layer is set to be much lower than room temperature, the degree of stretching of the alignment film molecules becomes small, but the pretilt angle distribution is good in experiments.

The above is easily understood from the difference in the degree of stretching depending on temperature.

In addition, when rubbing the entire surface of a substrate with a resin layer with fibers, etc.,
When the linear contact portion between the fiber and the substrate is temporally scanned over the entire surface of the substrate, when the portion of the substrate immediately after the contact is irradiated with infrared rays for a predetermined period of time, that is, the local portion of the resin layer is rubbed or rubbed. Immediately after, if infrared rays are irradiated instantaneously or for a short time and then allowed to cool, the pretilt angles will be very well aligned. This is understood to mean that the stretching of the alignment film molecules is aged by infrared rays.

ΔL may be 0, that is, infrared ray irradiation may be performed simultaneously with friction.

Ff the entire surface of the board with the resin layer using fibers, etc. When rubbing, the linear contact portion between the fiber and the substrate is temporally scanned over the entire surface of the substrate, and when the portion of the substrate immediately before the contact is irradiated with infrared rays for a predetermined time, that is, the local portion of the resin layer is
Immediately before friction or rubbing, infrared rays are irradiated instantaneously or for a short time, and immediately after that, when rubbing is performed while cooling, the pretilt angles are fairly consistent, and if a suitable alignment film material is selected, a large pretilt angle can be obtained. can get. This is because the molecules of the alignment film become more flexible due to infrared rays, and when rubbing is added to this, the above-mentioned effect appears to occur.

Note that the desirable wavelength of the infrared rays is 750 nm or more and up to about 10 microns.

Note that these effects are remarkable in so-called rotary rubbing.

Example The present invention will be explained in detail below.

In this example, polyamic acid resin (solvent type) was used as the resin. A polyamic acid resin can be imidized by a predetermined heat treatment, and in this example, a heat treatment capable of imidization was performed.

Commercially available polyamic acid resin (manufactured by Yasan Kagaku, 5E-411
Adjust the viscosity of 0) with a solvent and print it on a glass substrate using a printing machine.
Coated. This was heat-treated at a predetermined temperature. In this way, a resin layer made of polyimide was obtained.

Next, the resin layer was subjected to a rubbing treatment according to the present invention.

The substrates were bonded together in a predetermined direction with a predetermined gap maintained using a conventional method. In this case, the resin layer was oriented toward the void.

When this gap was filled with nematic liquid crystal, it was confirmed that the liquid crystal molecules were oriented in the desired direction on the glass substrate wall.

The pretilt angle of liquid crystal molecules was measured using the magnetic field method.

(Example 1) FIG. 1 shows a rubbing device involved in Example 1.

FIG. 1 is a schematic configuration diagram. In the figure, l is a table that moves in the direction of the arrow, 2 is a substrate, 3 is a rotating roll, and 4
is a fiber, and 5 is a heater for heating the table 1 and the substrate 2.

The temperature of the substrate during rubbing is approximately 50°C to approximately 150°C.
is easy to handle.

Generally, the pretilt angle can be made several degrees higher than before. Therefore, the twisting stability of liquid crystal molecules was improved.

Furthermore, the ability to regulate the alignment of liquid crystal molecules has also improved, as seen from the display on the liquid crystal panel. Also, the temperature of the board during rubbing should be adjusted to about 1
When the temperature is 00'C or higher, problems caused by static electricity during rubbing are significantly reduced.

(Example 2) FIG. 2 shows a rubbing device related to the second embodiment.

FIG. 2 is a schematic configuration diagram. In the figure, 11 is a table cooled by a refrigerant that moves in the direction of the arrow, 12 is a substrate, 13 is a rotating roll, 14 is a fiber, and 15 is a cooling device that is cooled to the substrate so that moisture does not condense on the substrate. A nozzle for blowing dry air.

The temperature of the substrate during rubbing is easily manageable at about O'c to about -io'c.

The display on the resulting liquid crystal panel was uniform, which is consistent with the uniformity of the pretilt angle measurement results.

(Example 3) FIG. 3 shows a rubbing device involved in Example 3. Third
The figure is a schematic configuration diagram. In the figure, 21 is a table that moves in the direction of the arrow, 22 is a substrate, 23 is a rotating roll,
24 is a fiber, 25 is an infrared lamp, and the base l7f22
is irradiated with an infrared lamp 25 before being rubbed with fibers 24.

-C, the pretilt angle can be made several inches higher than before. Therefore, the twisting stability of the liquid crystal molecules is improved.

Furthermore, the ability to regulate the alignment of liquid crystal molecules has also improved, as seen from the display on the liquid crystal panel.

(Example 4) FIG. 4 shows a rubbing device involved in Example 4.

FIG. 4 is a schematic configuration diagram. In the figure, 31 is a table that moves in the direction of the arrow, 32 is a substrate, 33 is a rotating roll, 34 is a fiber, 35 is an infrared lamp, and 32 is a substrate.
is rubbed with a fiber 11i34 and then irradiated with an infrared lamp 35.

-i, the distribution of pretilt angles is considerably reduced compared to the conventional one. Perhaps because of this, the display on the liquid crystal panel has become more uniform.

Example 1. Example 2. Example 3. In Example 4, the circumferential speed of the rotating roll is much greater than the moving speed of the table.

Effects of the Invention The present invention provides a method for producing a resin film for aligning liquid crystal molecules, and has great industrial value.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are schematic configuration diagrams of a rubbing device according to the present invention. 1.21.31... A platform that moves in the direction of the arrow,
11... A stand cooled by a refrigerant that moves in the direction of the arrow, 2, 12, 22. 32... A substrate,
3゜13.23.33・・・Rotating roll, 4
, 14゜24.34...fiber, 5...
A heater for heating the table l and the substrate 2, 15...
...Nozzle for blowing cooled dry air onto the board to prevent moisture from condensing on the board, 25.35/old/
・Infrared lamp. Name of agent: Patent attorney Shigetaka Awano, 1'4

Claims (4)

[Claims] (1) A method for producing an alignment film for a liquid crystal, which comprises keeping a substrate having a resin layer at a temperature of about 50° C. or higher, and rubbing the surface of the resin layer with a fiber or the like. (2) Maintaining the substrate having the resin layer at a temperature of about 0°C or less,
A method for producing an alignment film for a liquid crystal, characterized in that the surface of the resin layer is rubbed with a fiber or the like. (3) When rubbing the entire surface of the substrate with a resin layer with fibers, etc.
The liquid crystal is characterized in that when the linear contact portion between the fiber and the substrate temporally scans the entire surface of the substrate, a portion of the substrate immediately before contact or a portion of the substrate immediately after contact is irradiated with infrared rays for a predetermined period of time. Production method of alignment film for use. (4) A method for producing an alignment film for liquid crystal according to claims 1, 2, and 3, wherein the fibers are rotated relative to the substrate surface.