JPH0798443A - Method for cleaning substrate for liquid crystal display panel - Google Patents

Abstract

PURPOSE:To reduce the contamination with org. matter in chemical cleaning, to more efficiently clean off the inorg. matter contained in the org. matter, to improve the wettability of a substrate, to improve the physical cleaning effect and further to obtain the uniform substrate without any spot after drying. CONSTITUTION:UV is radaited to break the chemical bond of the org. matter on a substrate, the molecule with the bond broken is oxidized with the ozone generated by the radiation of UV or excited oxygen atom to decompose, vaporize and remove the org. matter by optical cleaning, and then the substrate is chemically and/or physically cleaned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process in manufacturing a liquid crystal display panel, and more particularly to a method for cleaning a liquid crystal display panel substrate used in manufacturing a liquid crystal display panel.

[0002]

2. Description of the Related Art Generally, a substrate for a liquid crystal display panel is washed to remove the contamination on its surface. Examples of the surface contamination include organic substances (paper, fibers, dandruff, oil and fat, saliva, etc.), inorganic substances (floating dust, glass scraps, etc.), and residual fine particles. In order to clean these contaminants, chemical cleaning, physical cleaning, or a combination of chemical cleaning and physical cleaning is performed.

However, chemical cleaning uses CFCs and harmful organic solvents whose use has been decided to be abolished internationally, so that there is a problem in that their application is restricted. Further, the physical cleaning has a problem that spots and unevenness are generated after drying.

In order to solve such a problem, Japanese Unexamined Patent Publication (Kokai) No. 5-34652 discloses a method of manufacturing a liquid crystal display element such as an STN type, in which physical cleaning including brush cleaning, ultrasonic cleaning and shower cleaning is performed. After going, UV /
A method of performing ozone cleaning is disclosed. However, these cleaning methods are mainly used in a display device that requires an alignment film such as a TN type or an STN type, and a substrate for a liquid crystal display device that does not require a polymer dispersion type or phase transition type alignment film. For, there was no efficient cleaning method.

[0005]

As described above, there are problems with both chemical cleaning and physical cleaning. UV / ozone cleaning is an effective method to solve the problems of chemical cleaning and physical cleaning, but it is used in the finishing process performed at the end of the cleaning process and does not improve the effects of chemical cleaning and physical cleaning. Absent. Furthermore, it does not affect the improvement of spots and unevenness during drying.

The problem to be solved by the present invention is to more efficiently wash a substrate for a liquid crystal display panel, in particular, a polymer dispersion type or phase transition type substrate which does not require an alignment film. Surely done, the stains after drying,
It is to provide a cleaning method for removing the occurrence of unevenness.

[0007]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to solve the above problems, and as a result, achieved the present invention.

That is, in order to solve the above problems, the present invention breaks the chemical bonds of organic substances on a substrate by radiating ultraviolet rays and radiates the ultraviolet rays to the molecules of the organic substances whose bonds are dissociated. A liquid crystal display characterized by chemically cleaning and / or physically cleaning the substrate after performing optical cleaning by decomposing, vaporizing and removing the organic matter by oxidizing with ozone or excited oxygen atoms generated by A method for cleaning a panel substrate is provided.

The ultraviolet rays used in the cleaning method of the present invention are
It is an ultraviolet ray having peaks at wavelengths of 185 nm and 254 nm,
As a radiation source of ultraviolet rays, for example, an output of 30 to 500 W
Low pressure mercury lamp.

The chemical cleaning used in the cleaning method of the present invention includes, for example, wet cleaning using pure water, an alkaline solution, an acid solution, CFC, an organic solvent or the like as a cleaning solution.

Examples of the physical cleaning used in the cleaning method of the present invention include scrub cleaning, shower cleaning and ultrasonic cleaning.

Examples of the drying after washing include spin drying, air knife drying, IPA vapor drying, freon vapor drying and the like.

[0013]

In the present invention, since the organic substances on the substrate are decomposed by the ultraviolet / ozone cleaning to perform the chemical cleaning, the contamination of the organic substances during the chemical cleaning is reduced, and the cleaning property of the inorganic substances trapped by the organic substances is improved. Can be improved. Further, the decomposition of the organic matter improves the wettability of the substrate surface, and more effective physical cleaning can be performed. Further, it is possible to obtain a substrate without stains or unevenness after drying. By improving these cleaning effects, when the liquid crystal material or the light control layer forming material composed of the liquid crystal material and the polymerizable composition is injected into the panel, uniform and even injection can be performed, and the injection speed can be improved. Therefore, the cleaning method of the present invention contributes to efficiently manufacture a high-performance and highly reliable liquid crystal display panel.

[0014]

EXAMPLES The present invention will now be described more specifically by showing examples of the present invention. However, the invention is not limited to these examples.

Example 1 A glass substrate with an ITO electrode (3
Ultraviolet light having peaks at wavelengths of 185 nm and 254 nm was irradiated for 2 minutes on a (00 mm square, 1.1 mm thickness) using a low pressure mercury lamp. At that time, the output of the low-pressure mercury lamp was 380 W, and the distance between the low-pressure mercury lamp and the glass substrate was 80 mm. This substrate was ultrasonically cleaned with pure water for 2 minutes (frequency 27 kHz, output 1200 W). After washing, when the substrate was slowly pulled up from pure water, there were no water droplets, and after naturally drying as it was, the surface was illuminated with a high-intensity lamp and visually observed, and there were no traces of water droplets. In addition, the paper burn that had adhered before cleaning was reduced.

Comparative Example 1 The same glass substrate as in Example 1 was ultrasonically cleaned with pure water for 2 minutes (frequency: 27 kHz,
The output was 1200 W). After washing, the substrate was slowly pulled up from pure water, and many water droplets were attached to the surface. After air-drying as it was, the surface was illuminated with a high-intensity lamp and visually observed. As a result, traces of water droplets were attached, and there was almost no change in paper burning.

(Example 2) A substrate subjected to the same UV cleaning as in Example 1 was washed with a cleaning solution ("Extran M" manufactured by Merck & Co., Inc.).
After ultrasonic cleaning (frequency 27 kHz, output 1200 W) for 2 minutes using "A-02" 3% aqueous solution), rinse with a pure water shower. The substrate after rinsing had no water droplets attached, and after natural drying, the surface was illuminated with a high-intensity lamp and visually observed, and it was found that there were no traces of water droplets and no paper burn.

Comparative Example 2 The same glass substrate as in Example 1 was washed in the same manner as in Example 2 without UV washing. Water droplets adhered to the substrate after rinsing, and after natural drying, when the surface was illuminated with a high-intensity lamp and visually observed, there were traces of water droplets and paper burns still remained.

(Embodiment 3) A glass substrate with ITO electrodes (300 mm square, 1.1 mm thickness) washed in the same manner as in Embodiment 2
One-component epoxy adhesive manufactured by Rodic "DSA-00
1 "is applied to the peripheral portion excluding the injection hole portion at one place and the other substrate on which the 12.0 μm glass fiber spacers are scattered, and the applied adhesive is heat-cured to cure the liquid crystal display panel. A cell was prepared.

80% by weight of "PN-001" (nematic liquid crystal composition) manufactured by Roddick having the following physical properties as a liquid crystal material, and "H" manufactured by Nippon Kayaku Co., Ltd. as a polymerizable composition.
X-220 "(caprolactone-modified hydroxypivalic acid neopentyl glycol diacrylate) 19.6% by weight, Ciba Geigy's" Irgacure 651 "(benzyl dimethyl ketal) 0.4% by weight as a polymerization initiator.
A light control layer forming material was prepared.

The physical properties transition temperature 68.5 ° C. of the liquid crystal "PN-001" (N-I) <-25 ℃ (C-N) refractive index n _e = 1.787 n _o = 1.583 refractive index anisotropy Δn = 0.254 Threshold voltage Vth = 1.15 V Viscosity at 20 ° C. 59 c. p. Dielectric anisotropy Δε = 26.9

The light control layer forming material and the cell were placed in a vacuum injecting device, and the light control layer forming material was defoamed and the pressure in the cell was reduced. Then, the light control layer forming material was brought into contact with the injection port of the cell, and nitrogen was introduced to gradually raise the pressure in the device so that the pressure in the vacuum injection device became atmospheric pressure in 1.5 hours. The light layer forming material was injected into the cell. After 1.5 hours, it was taken out of the injection device, the injection port was sealed, and ultraviolet rays were irradiated using a high pressure mercury lamp to obtain a light control panel.

Observation of the panel revealed that the material for forming the light control layer had been injected into the entire panel and that there was no white turbidity.

When the light control layer of the obtained liquid crystal device was observed with an electron microscope, a three-dimensional mesh-like transparent polymer substance was confirmed.

(Comparative Example 3) A glass substrate with ITO electrodes (300 mm square, 1.1 mm thick) washed in the same manner as in Comparative Example 2
Was used to obtain a light control panel in the same manner as in Example 3.

Observation of the obtained light control panel revealed that only 70% of the entire light control layer was injected with the light control layer-forming material, and white turbidity was observed.

[0027]

According to the method of cleaning a substrate for a liquid crystal display panel of the present invention, chemical cleaning can be performed after the organic substances on the substrate are decomposed by irradiating with ultraviolet rays, so that the contamination of organic substances during the chemical cleaning can be prevented. It is possible to reduce the cleaning property of the inorganic substances captured by the organic substances. Further, the decomposition of the organic matter improves the wettability of the substrate surface, and more effective physical cleaning can be performed. Furthermore, after drying,
It is possible to obtain a substrate without spots or unevenness. By improving these cleaning effects, when injecting the light control layer forming material into the cell in the manufacturing process of a polymer dispersion type or phase transition type liquid crystal display panel, the injection can be performed uniformly and evenly,
The injection speed can be improved. Therefore, the cleaning method of the present invention contributes to efficient production of a high-performance and highly reliable liquid crystal display panel.

Claims (1)

[Claims] 1. A chemical bond of an organic substance on a substrate is cut by radiating an ultraviolet ray, and a molecule of the organic substance whose bond is dissociated is oxidized by ozone or an excited oxygen atom generated by radiating the ultraviolet ray. By performing the optical cleaning by decomposing, vaporizing and removing the organic matter, the method for cleaning the substrate for a liquid crystal display panel is characterized by chemically cleaning and / or physically cleaning the substrate.