JPH05134254A - Orientation treatment and liquid crystal display using the treatment - Google Patents

Abstract

PURPOSE:To realize a uniform display state over the entire surface of the liquid crystal display element. CONSTITUTION:A high-polymer resin coating film provided on a liquid crystal supporting plate 13 is subjected to a surface treatment by an ultrasonic cleaning device in warm water 11 and is then subjected to a rubbing treatment, by which an oriented film for the liquid crystal is obtd. Two sheets of the substrates treated in such a manner are stuck to each other in such a manner that the surfaces of the oriented films face each other via a spacer, by which the liquid crystal display element is produced.

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 and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art In a liquid crystal display device, a coating film of a polymer resin such as polyimide is generally provided on a glass substrate provided with a transparent electrode layer made of indium tin oxide (hereinafter abbreviated as ITO). There is known a method in which an alignment treatment is performed by providing a coating film and rubbing the coating film in a specific direction (rubbing method) using a roll around which a buff cloth made of organic fibers is wound immediately after being provided.

[0003]

However, in the conventional alignment treatment method in which the rubbing treatment is performed after the coating of the polymer resin is formed, the contact area between the coating and the buff cloth during rubbing is large and the surface of the coating is charged. In some cases, shavings of the coating film and fiber scraps from the buff cloth may adhere to the surface of the coating film and proceed to the next step.
It causes various defects such as a gap defect between substrates.

That is, the liquid crystal display element using the conventional alignment treatment method has a problem that the display quality is deteriorated.

In view of the above problems of the conventional alignment treatment method, the present invention provides an alignment treatment method free from such a gap defect and deterioration of display quality, and a liquid crystal display device using the same. It is intended.

[0006]

The alignment treatment method of the present invention comprises:
A polymer resin coating film provided on a liquid crystal support plate having a transparent electrode is subjected to a surface treatment by applying ultrasonic waves in cold water or warm water, and then the surface of the polymer resin coating film subjected to the surface treatment is rubbed. It is an alignment treatment method characterized by performing an alignment treatment by a method.

Further, the present invention is a liquid crystal display device in which a liquid crystal compound is filled in a facing interval of a pair of liquid crystal support plates having a polymer resin coating film subjected to such an alignment treatment method on the surface. is there.

[0008]

In the present invention, the surface of the polymer resin coating film is formed by forming irregularities on the surface of the coating film by ultrasonic waves in cold water or warm water to reduce the contact area between the coating film and the buff cloth during rubbing. It is possible to reduce the amount of static electricity generated on the surface of the coating film, reduce the adhesion of shavings of the coating film to the surface of the coating film, and the adhesion of fiber scraps from the buff cloth, and it is possible to manufacture a liquid crystal display element with uniform display quality.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An alignment treatment method according to an embodiment of the present invention and a liquid crystal display device using the same will be described below with reference to the drawings.

FIG. 1 is a diagram showing an alignment treatment method of the present invention. A liquid crystal support plate 13 having an ITO electrode layer provided with a polymer resin coating film was placed in a substrate cleaning cassette 15, and 70
Put in 11 ℃ of warm water. This tank 11 of warm water is placed on the pedestal 16 of the ultrasonic cleaning device 14, filled with water 12, and the frequency is 28 kHz, 45 by the dyna shock method.
Ultrasonic waves of 100 kHz and 100 kHz are generated for a certain period of time, after which the liquid crystal support plate 13 provided with a coating film is pulled up to evaporate water droplets adhering to the surface, and subsequently, as shown in FIG. The surface of the polymer resin coating film 22 subjected to the above-mentioned surface treatment was rubbed by using a roll around which 21 was wound.

FIG. 3 is a diagram showing the structure of a liquid crystal display element produced by using an alignment film obtained by subjecting the polymer resin coating film 22 to the above surface treatment and rubbing treatment. After forming an ITO layer on a substrate made of glass or plastic, and forming a polymer resin coating film on it, first, the coating film is subjected to the above-mentioned surface treatment by ultrasonic waves, and then alignment by rubbing is performed. Two liquid crystal support plates 31 and 32 having a treated alignment film are prepared, a spacer / sealing resin 35 is printed on one of the support plates 31, and the two liquid crystal support plates 31 and 32 are bonded to each other to form an opening. A nematic liquid crystal was injected from No. 36. afterwards,
The opening 36 was sealed to produce a liquid crystal display element. continue,
The liquid crystal was heated to a temperature at which it exhibited isotropicity, annealed at that temperature for 1 hour, and then gradually cooled to complete a liquid crystal display element. A more specific example will be described below.

(Example 1) A commercially available polyimide-based alignment film (hereinafter referred to as alignment film A. Alignment film A exhibits a pretilt angle of 4 to 5 degrees) is diluted with a dedicated thinner.
A 0% by weight solution was prepared. Then, this solution is ITO
23 using a spinner on a glass substrate with an electrode pattern
Spin coating was performed at 00 rpm for 1 minute. 8 after application
After drying at 0 ℃ for 15 minutes and evaporating the solvent, 250 ℃
Curing was carried out for 1 hour to form a coating film of the alignment film A on the glass substrate. Subsequently, the glass substrate on which the coating film of the alignment film A was formed was dipped in warm water at 70 ° C. as shown in FIG. 1 and surface-treated by the ultrasonic cleaning device 14 for 15 minutes. The surface roughness of the coating film thus surface-treated had a maximum height R _max of 54 × 10 ⁻² μm.

After that, the surface of the washed coating film was rubbed in the same direction 10 times using a roll around which a woven rayon cloth was wound to perform rubbing treatment to complete an alignment film for liquid crystal. The amount of charge on the surface of the coating film during rubbing was measured with a surface potential measuring device and found to be -80 V at a distance of 1.0 cm from the surface of the film.

Two liquid crystal support plates on which a polyimide alignment film for liquid crystal (alignment film A) is formed by such a treatment are prepared. As shown in FIG. 3, one support plate (for example, lower liquid crystal support plate 31) is prepared. ) An acid anhydride-curable epoxy resin in which glass fibers having a diameter of 6.0 μm are dispersed as a spacer / seal resin 35 on the surface on which the alignment film is formed is provided on only one side and 5 on the center of the side.
The width of 0.2 mm is printed around the edges of the alignment film formed on the upper liquid crystal support plate 31 and the lower liquid crystal support plate 32 so that the rubbing directions 33 and 34 are parallel to each other. Pressure was applied in a state where the surfaces were opposed to each other, and curing adhesion was performed by heating at 140 ° C. for 4 hours. After adhering, nematic liquid crystal (manufactured by Chisso Corporation, trade name MA-4051XX) was injected by vacuum injection, and after injection, the opening 36 was sealed with a commercially available acid anhydride-curable epoxy resin. After sealing, the liquid crystal was heated to a temperature at which the liquid crystal was isotropic, annealed at that temperature for 1 hour, and then slowly cooled to complete a liquid crystal display element. The liquid crystal display device thus completed showed a uniform and good quality display state with less dust.

Example 2 A commercially available polyimide-based alignment film different from the alignment film A used in Example 1 (hereinafter referred to as alignment film B. The alignment film B exhibits a pretilt angle of 7 to 8 degrees).
Was diluted with a dedicated thinner to prepare a 3.0 wt% solution. Then, this solution was spin-coated with a spinner at 2300 rpm for 1 minute on a glass substrate on which an ITO electrode pattern was formed. After coating, the coating film was dried at 80 ° C. for 15 minutes to evaporate the solvent and then cured at 200 ° C. for 1 hour to form a coating film of the alignment film B on the glass substrate. Subsequently, the glass substrate on which the coating film of the alignment film B was formed was immersed in hot water at 70 ° C. as shown in FIG. 1, and surface treatment was performed for 15 minutes by the ultrasonic cleaning device 14. The surface roughness of the coating film thus surface-treated has a maximum height R _max of 59 × 10 ^-2.
was μm.

After that, the surface of the coating film was rubbed 10 times in the same direction using a roll around which a woven rayon cloth was wound, and a rubbing treatment was performed to complete an alignment film for liquid crystals. The amount of charge on the surface of the coating film during rubbing was -9 at a distance of 1.0 cm from the surface of the film.
It was 0V.

A liquid crystal display device produced by using the polyimide alignment film for liquid crystal (alignment film B) obtained by the above-mentioned treatment in the same manner as in Example 1 below has good quality with less dust. The display state was shown.

Comparative Example 1 A commercially available polyimide-based alignment film (alignment film A) was diluted with a dedicated thinner to give 3.0% by weight.
Was prepared. Then, this solution was spin-coated with a spinner at 2300 rpm for 1 minute on a glass substrate on which an ITO electrode pattern was formed. 1 at 80 ℃ after coating
After drying for 5 minutes to evaporate the solvent, the coating was cured at 250 ° C. for 1 hour to form a coating film of the alignment film A on the glass substrate.
The surface roughness of the coating film has a maximum height R _max of 32 × 10 ^-2 μm.
Met. Immediately after that, the surface of the coating film was rubbed 10 times in the same direction by using a roll around which a woven rayon cloth was wound to perform rubbing treatment to complete an alignment film for liquid crystal. The amount of charge on the surface of the coating film during rubbing is 1.0 cm away from the surface of the film.
It was 150V.

A liquid crystal display element manufactured by using the polyimide alignment film for liquid crystal (alignment film A) obtained by the above-mentioned treatment in the same manner as in Example 1 below has dust such as polyimide shavings. Conspicuously, the display appearance was impaired, and a uniform display state was not obtained.

In the above embodiment of the present invention, the ultrasonic cleaning is carried out in warm water, but the cleaning is not limited to this and may be carried out in cold water.

[0021]

As is apparent from the above description, according to the present invention, when the polymer resin coating film formed on the liquid crystal support plate is formed with irregularities on the surface of the coating film by ultrasonic waves, it is generated during rubbing. The amount of electrification to be reduced, the adhesion of dust such as shavings of the coating film to the coating film surface and fiber scraps from the buff cloth can be reduced, and by using the alignment film made of the polymer resin subjected to the above treatment, It has an advantage that a liquid crystal display device with uniform display quality can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an alignment treatment method of the present invention.

FIG. 2 is a diagram showing how a coating film is rubbed in the present invention.

FIG. 3 is a diagram showing a configuration of a liquid crystal display device manufactured by using an alignment film made of a polymer resin coating film manufactured by the alignment treatment method of the present invention.

[Explanation of symbols]

 11 ... Warm water 12 ... Water 13 ... Liquid crystal support plate provided with polymer resin coating film 14 ... Ultrasonic wave generator 15 ... Substrate cleaning cassette 16 ... Cradle 21 ... Rayon woven cloth 22 ... Polymer resin coating film 23 ... Liquid crystal Support plate 31 ... Upper side liquid crystal support plate 32 ... Lower side liquid crystal support plate 33 ... Rubbing treatment direction of upper side liquid crystal support plate 34 ... Removing treatment direction of lower side liquid crystal support plate 35 ... Spacer / seal resin 36 ... Aperture

Claims (2)

[Claims] 1. A polymer resin coated on a liquid crystal support plate having a transparent electrode is subjected to a surface treatment by applying ultrasonic waves in cold water or warm water, and further subjected to the surface treatment. An alignment treatment method characterized by subjecting a coating film surface to an alignment treatment by a rubbing method. 2. A liquid crystal wherein a liquid crystal compound is filled in a facing interval of a pair of liquid crystal support plates having on the surface thereof a polymer resin coating film subjected to the alignment treatment method according to claim 1. Display element.