JPH07333613A - Rubbing method - Google Patents

Abstract

PURPOSE:To remove particulates adhered on a long-sized film substrate and to improve a yield by passing this substrate through an electric removing device and an ultrasonic dust removing device at the time of continuously rubbing the surface of the oriented film of the substrate described above by a rubbing roll. CONSTITUTION:The film delivered from a film substrate delivery 1 is subjected to removal of static electricity, such as electrification by peeling, in the electric removing device 2 and is sent to the ultrasonic dust removing device 3. The ultrasonic dust removing device 3 consists of a wind blow-off port 4 and wind suction port 5 which are ultrasonic oscillators. These ports are so formed that the balance of blowing off and sucking is obtd. in a casing hood 6. The air having ultrasonic vibration energy blows off the particles adhered on the film surface at the time the film substrate passes these ports. Next, the film is subjected to a rubbing treatment by the rubbing roll 7. The dust of the rubbing cloth, etc., adheres to the film on account of the static electricity by the rubbing in this treatment. The dust is removed by passing the film substrate through the ultrasonic dust removing device 8 and the final static electricity removing device 9 in succession thereto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for aligning liquid crystal molecules in an optical film using liquid crystals.

[0002]

2. Description of the Related Art As a method of aligning liquid crystal molecules in a liquid crystal cell or the like, there is known a method of forming an alignment film on the surface of a substrate and rubbing the surface of the alignment film in one direction with a rubbing roll. By the way, when aligning liquid crystal molecules on the surface using a film substrate as a substrate, it is inefficient to perform rubbing treatment for each substrate of each size like a liquid crystal cell. -It is more efficient to perform rubbing by continuous processing with two rolls.

On the other hand, in the rubbing treatment, fine dust adheres to the substrate and causes scratches during rubbing, resulting in defects in the liquid crystal alignment, which lowers the product yield. As a method of removing these dusts, a method is known in which static electricity is removed from the surface of the substrate and the dust is blown off with an air knife. However, in this method, due to the viscous resistance of air, the fine particles adhering to the boundary layer and below cannot be removed because the effect of the air knife is not exerted. On the other hand, there is a method of directly ultrasonically vibrating the substrate to fly off the adhered fine particles, but the vibration at the time of rubbing cannot be carried out because the disturbance in the rubbing direction occurs, and it is not possible in the pretreatment. The effect is not enough.

[0004]

With the recent increase in the size of liquid crystal display panels, the decrease in yield due to the defects caused by dust has become a serious problem. Further, with the miniaturization of images, the size of defects has become a problem of submicron. Furthermore, with the addition of a wider and faster rubbing process, there has been an urgent need to develop a method for reliably and quickly removing fine particles. An object of the present invention is to effectively and quickly remove fine particles adhering to a long film, and to improve the yield in the step after the rubbing treatment.

[0005]

Means for Solving the Problems The above-mentioned problems are solved by a static eliminator and an ultrasonic dust eliminator when continuously rubbing the surface of an alignment film with a rubbing roll on a long film substrate having an alignment film formed on one surface. It is achieved by a continuous rubbing method of a long film, which is characterized by passing through a device.

FIG. 1 shows a typical device of the present invention. In FIG. 1, the film sent from 1 removes static electricity such as peeling charge by the static eliminator 2 and is sent to the ultrasonic dust remover 3. This ultrasonic dust remover is composed of a wind blow-out port 4 and a wind suction port 5 which are ultrasonic oscillators, and the blow-in suction is balanced in a casing hood 6. When the film substrate passes through here, air having ultrasonic vibration energy blows off the adhered particles on the film surface. In this method, the substrate is not vibrated and the fine particles are repelled, but the vibration of the air is transmitted to the fine particles and the fine particles are repelled, so that there is no substrate vibration and there is no disturbance in the rubbing direction during rubbing. The ultrasonic frequency used here is from 20 kHz to 200
kHz, preferably 25 kHz to 100 kHz is used. By this treatment, the film surface particles are removed, and the rubbing treatment is carried out by the next rubbing roll 7. In this rubbing process, dust such as rubbing cloth adheres to the film surface due to static electricity due to rubbing. The step of removing this passes through the ultrasonic dust remover 8 and the final static eliminator 9 following it, and the rubbing step is completed.
The static eliminator has an oscillating frequency of 10,000 Hz to 50,000 Hz, preferably 100
High-frequency ion generation from 00 Hz to 30,000 Hz is performed. In this way, a rubbing-free film without dust is continuously obtained through the process according to the present invention. The present invention is characterized in that the static eliminator and the ultrasonic dust remover are passed therethrough, and the order of installing them is not limited, but it is preferable to first install the static eliminator and then the ultrasonic dust remover. Further, the installation position is not limited, either, but both may be installed at the same time before or after the rubbing roll, or both may be installed separately. Most preferably, both are used simultaneously before and after the rubbing roll, as shown in FIG.

A polyimide film is a typical example of the alignment film. This is applied by coating polyamic acid (for example, SE-7210 manufactured by Nissan Chemical Industries, Ltd.) on the surface of the support at 100 ° C.
Nematic liquid crystal or discotic liquid crystal can be aligned by rubbing after firing at 300 to 300 ° C. Further, a coating film of an alkyl chain-modified Poval (for example, MP203 and R1130 manufactured by Kuraray Co., Ltd.) need not be baked, and the orientation ability can be imparted only by rubbing. In addition, almost any organic polymer film such as polyvinyl butyral or polymethylmethacrylate that forms a hydrophobic surface can be given a liquid crystal aligning ability by rubbing the surface. A typical example of the inorganic oblique vapor deposition film is a SiO oblique vapor deposition film. this is,
Si in the vacuum chamber from the diagonal direction to the base film surface
O vaporized particles are applied to form an obliquely vapor-deposited film having a thickness of about 20 to 200 nm to form an alignment film. When the liquid crystal is oriented by this vapor deposition film, the optical axis of the liquid crystal layer is directed to a specific direction on a plane perpendicular to the surface of the base film, including the trajectory of the SiO vapor deposition particles.

The rubbing-treated film thus obtained is used as an optically anisotropic film for compensating the viewing angle of a liquid crystal cell or a liquid crystal display panel. In the optically anisotropic film which can be used in the present invention, for example, after forming an alignment film on a transparent film, rubbing is performed by the device of the present invention, and then, for example, the following discotic liquid crystal.

[0009]

[Chemical 1]

An optical compensation sheet having an optical anisotropy is applied by applying a layer containing the above and heat-treating the liquid crystal at a temperature above the discotic nematic liquid crystal phase-solid phase transition temperature to form an optical compensation sheet having optical anisotropy. . The discotic liquid crystal molecules that have once been oriented are oriented at an angle θ with respect to the support surface, but in the one-component system, the angle of oblique orientation does not change much depending on the type of alignment film, and may take a value specific to the discotic liquid crystal molecules. Many. When two or more discotic liquid crystal molecules are mixed, the tilt angle can be adjusted within a certain range by the mixing ratio. Therefore, for controlling the tilt angle of the oblique alignment, it is effective to select a discotic liquid crystal type and further mix two or more types of discotic liquid crystal molecules.

[0011]

【Example】

Example 1 A 127 μm thick film of triacetyl cellulose (when the refractive index in two directions orthogonal to each other in the film plane is nx, ny, the refractive index in the thickness direction is nz, and the thickness d = 127 μm (nx-ny) × d = 20 (nm), {(nx-ny)
/ 2-nz} xd = 95 (nm) was used as a support, and an alkyl-modified Poval (MP302 manufactured by Kuraray Co., Ltd.) was applied thereon as an alignment film so as to have a thickness of 2 μm. This is rubbed with a rubbing machine equipped with the static eliminator of the present invention and an ultrasonic dust eliminator shown in FIG.
A discotic liquid crystal material prepared by mixing 1 and TE-1 in a blending ratio of 4: 1 was dissolved in methyl ethyl ketone solution to make 10 wt% and the resulting solution was 300 by a spin coater.
Coating was carried out at 0 rpm to make a film having a layer containing a discotic liquid crystal having a thickness of 1 μm. This film 1
After putting it in a constant temperature bath set at 45 ° C for 5 minutes,
The discotic liquid crystal layer was aligned by bringing it into contact with a metal surface set at 20 ° C. and rapidly cooling it, to prepare an optical compensation film having optical anisotropy. The number of fine particles on the surface of the film thus formed was observed with an electron microscope.

Example 2 This film was applied to a TN type liquid crystal cell (the product of the difference in refractive index between the extraordinary light and the ordinary light of the liquid crystal and the gap size of the liquid crystal cell was 510 n).
It was mounted at a twist angle of 87 ° at m as shown in FIG. 3 and the visibility was evaluated by an actual image.

Comparative Example The number of fine particles on the surface of the optical compensation film produced in the same manner as in Example 1 except that the conventional apparatus shown in FIG. 2 was used for rubbing instead of the apparatus of the present invention was observed with an electron microscope. Further, this film was mounted on the same TN cell as in Example 2 with the same constitution, and the visibility evaluation (pixel defect) was observed.

Table 1 shows the results of electron microscopic observation and the results of the visibility of the liquid crystal surface plates prepared using these films.

[0015]

[Table 1]

[0016]

From the results shown above, it was found that the dust remover of the present invention is extremely effective when continuously rubbing a film substrate, and a liquid crystal display panel having no pixel defects can be obtained.

[Brief description of drawings]

FIG. 1 shows a rubbing processing apparatus according to an embodiment of the present invention.

FIG. 2 shows a conventional alignment treatment apparatus.

FIG. 3 shows a structure of a TN type liquid crystal display panel.

[Explanation of symbols]

 1: Sending out a film substrate 2: Static eliminator 3: Ultrasonic dust remover 4: Ultrasonic oscillator and wind outlet 5: Wind suction port 6: Casing hood 7: Rubbing roll 8: Ultrasonic dust remover 9: Static eliminator 10: Winding of film substrate 11: Air knife TNC: TN type liquid crystal cell A, B: Polarizing plate PA, PB: Polarization axis RF1, RF2: Optical compensation film BL: Backlight R1, R2: Rubbing direction of optical compensation film

Claims (1)

[Claims] 1. A static electricity eliminator and an ultrasonic dust eliminator are passed when continuously rubbing the surface of the alignment film with a rubbing roll on a long film substrate having an alignment film formed on one surface. Continuous rubbing method for long film.