JPH11101909A - Color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color filter having an overcoat layer (OC) which can orient a liquid crystal by rubbing, by adding a liquid crystal orienting ability to a protective film. SOLUTION: The liquid crystal orienting ability is imparted by rubbing an OC of a color filter for a color liquid crystal display device. Namely, this color filter consists of a transparent substrate 2, specified pixel groups 3 formed on the transparent substrate 2, and a protective film 4 formed on the specified pixel groups 3. The protective film 4 has liquid crystal orienting ability. In this case, a three-dimensionally crosslinked resin is preferably used for the protective film 4. In the production of the color filter above described, after the OC is formed, the surface of the OC is subjected to rubbing to give liquid crystal orienting ability. The rubbing treatment is carried out, for example, by using a velvet rubbing cloth such as nylon and rayon wound on a roller and bringing the rotating roller surface into contact with the OC surface to rub. Thus, the liquid crystal molecules are oriented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color filter used in a color liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal displays (hereinafter abbreviated as LCDs)
Utilizing features such as thinness, small size, and low power consumption, is currently used for display units such as watches, calculators, TVs, and personal computers. In recent years, color LCDs have been developed and OA / AV
It has begun to be used in many applications such as navigation systems and viewfinders, mainly in equipment, and the market is expected to expand rapidly in the future.

As shown in FIG. 1, a color filter for displaying a color image on an LCD is formed on a substrate 2 such as a glass plate on which a BM (black matrix) 1 having a lattice pattern is formed. 3) Color pixels 3 (about 100 × 100 × 2 μm) composed of B (blue) are sequentially formed, and a transparent protective film (overcoat layer, OC) 4 is formed thereon. 5 is a polarizing plate and 6 is an ITO electrode.

[0004] In the color LCD, the color filter 7 has an LC
D, the display screen can be colored by transmitting backlight light through a color filter. 8 is an alignment film, 9 is a liquid crystal, 10 is a sealing material, 11 is a top coat layer, 12 is an ITO electrode, 13 is a substrate such as a glass plate, 14
Is a polarizing plate.

At present, color filters are mainly manufactured using a dyeing method. However, in this method, a step of forming a pixel by applying a transparent photosensitive resin on a glass substrate, drying, exposing, and developing, dyeing with a dye, and then forming a color mixing prevention layer is required to be repeated three times. Therefore, the number of steps is large and the cost is high. Further, since a dye is used as a coloring agent, there is a disadvantage that reliability (weather resistance and heat resistance), which is an important issue of a color filter, is inferior.
Therefore, some color filters using a pigment as a coloring agent have been proposed, among which are an electrodeposition method, a printing method, and a photolithography method (photolithography method).

However, the electrodeposition method requires the formation of an electrode pattern. (1) The degree of freedom of the pattern is small.
(2) The cost is high, and the printing method has problems such as (1) it is difficult to align a large substrate and the resolution is low, so it is difficult to cope with miniaturization, and (2) the flatness of the pattern is poor. The photolithography method is considered to be the mainstream. For photolithography, liquid resists and films are contemplated. The liquid resist is formed by applying a varnish obtained by dispersing a pigment in a photosensitive resin onto a glass substrate using a spinner, drying, exposing, developing, and thermosetting to form color pixels. On the other hand, the film is a film in which a varnish is formed into a film in the same manner as the photosensitive film for a printed board. After lamination on a substrate, color pixels are formed by exposure, development, and thermosetting. In addition, OC is mainly applied using a spin coating method, dried using a hot plate, and then heat-cured in an oven to manufacture. When OC is formed by a spin coating method, a solution-like protective film material is applied to the center of the substrate. The protective film material deposited on the substrate accumulates in a circle at the center of the substrate. If left as it is, the wet surface gradually expands in a circular shape, but is usually applied to the substrate with a uniform thickness by rotation of the substrate. The substrate coated with the solution protective film material is dried and thermally cured in an oven or the like to form a protective film. However, when the solution-like protective film material is applied to the substrate and rotated in a state of being wet in a circular shape, the wet shape of the circular shape becomes uneven in optical observation after curing. Unevenness can be easily observed under a monochromatic light source such as a sodium lamp. It is preferable that the color filter, which is an optical component, has no optical unevenness.

[0007]

Conventionally, OC has no function of aligning the liquid crystal. Therefore, when a liquid crystal display device is manufactured using a color filter, an alignment film is formed separately from the OC on a portion adjacent to the liquid crystal. 8 was arranged. Usually, a polyimide resin is used for the alignment film. However, many polyimide resins have an absorption in a visible light region and thus are colored or have insufficient transmittance, leading to a deterioration in quality of a liquid crystal display device. Insufficiency of coloring or transmittance becomes remarkable when the alignment film is thick, so that the alignment film is usually a thin film of 0.1 μm or less. As described above, the OC and the alignment film are manufactured in different processes. The present invention has been made as a result of intensive studies in order to use not only a three-dimensionally cross-linked resin as an OC but also an alignment film in consideration of using both an OC and an alignment film. It is a thing. That is, OC which can align liquid crystal by rubbing
Is provided.

[0008]

According to the present invention, there is provided a color filter characterized in that a liquid crystal alignment capability is imparted by rubbing OC of a color filter for a color liquid crystal display device. That is, the present invention is a color filter including a transparent substrate, a predetermined pixel group formed on the transparent substrate, and a protective film formed on the predetermined pixel group, wherein the protective film has a liquid crystal alignment ability. Is a color filter characterized by the following. A three-dimensionally crosslinked (bridged) resin can be preferably used as the protective film.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thickness of the OC used in the present invention is preferably 0.5 to 5 .mu.m. The thickness of the OC used in the present invention is more preferably 1 to 3 μm. The rotation speed of the spin coater is desirably 500 to 5000 rpm. The rotation speed of the spin coater is more desirably 500 to 2000 rpm. Drying after spin coating can be performed using a hot plate that is generally widely used. The hot plate temperature used for leveling is 30 ° C. to 130 ° C.
C is desirable. The temperature of the hot plate used for leveling is more preferably from 30C to 80C. In manufacturing the color filter of the present invention, after forming OC, O
A rubbing treatment is performed to impart liquid crystal alignment ability to the C surface. The rubbing treatment is a treatment in which a velvet-like rubbing cloth such as nylon or rayon is wound around a roller and rubbed so that the rotating roller surface and the OC surface are in contact with each other. Is obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. 2
35 parts by weight of 2′-bis [4-methacryloxy, polyethoxyphenyl] propane, γ-chloro-β-hydroxypropyl-β′-methacryloyloxyethyl-o-
15 parts by weight of phthalate, methacrylic acid / ethyl acrylate / ethyl acrylate (18/30/53 weight ratio)
50 parts by weight of copolymer resin, 2 parts by weight of 1,7 bis (9-acridinyl) heptane, hexamethoxymethyl melamine, methyl ethyl ketone, and anthraquinone (red), copper halide phthalocyanine (green), copper phthalocyanine (blue) The components were made uniform to obtain a photosensitive resin layer coating solution. The solution is coated on a 50 μm-thick polyethylene terephthalate film with a gravure coater (manufactured by Hirano Seiki Co., Ltd.), and a 30 μm-thick polyethylene film is laminated as a protective film to obtain a photosensitive film. The thickness of the colored photosensitive resin layer was 1.5 μm. Next, a glass substrate (0.7 mm × 370 mm) with a chromium film (0.1 μm thick)
X 470 mm) and a roll laminator (manufactured by Somar)
A photosensitive film is laminated at a substrate temperature of 80 ° C., a roll temperature of 80 ° C., a roll pressure of 6 kg / cm ² , and a speed of 0.5 m / min so that the colored photosensitive resin faces the substrate by using polyethylene terephthalate. After removing the film, the film was exposed through a negative mask using an exposure machine (manufactured by Hitachi Electronics Engineering Co., Ltd.) at 200 mJ / cm ² , and then a developing machine (manufactured by Mec Engineering Co., Ltd.)
Spray development is performed at 25 ° C. with a 0.3% by weight aqueous KOH solution for 20 seconds to remove unexposed portions. After draining and drying in the developing step, the film is heated and cured in a clean oven (manufactured by Tabai) at 200 ° C. to form a colored pattern of one color. This color forming process is repeated by using films of each color in the order of G, B, and R to form an RGB pixel pattern. RG
After the formation of the B pixel pattern, heating and curing are performed at 230 ° C. in a clean oven (manufactured by Tabai). next,
Using a spin-type resist coating and curing apparatus manufactured by Hitachi Chemical Techno-Plant Co., Ltd., an OC material HP manufactured by Hitachi Chemical Co., Ltd., which is a thermosetting resin (three-dimensionally crosslinked resin), is applied to a substrate having an RGB pixel pattern formed on its surface. After dispensing the -1009 (trade name) solution, the spin rise speed is 200 rpm.
/ Sec at a rotation speed of 800 rpm for 20 sec and a falling speed of 400 rpm / sec, and then automatically conveyed onto a multi-stage hot plate. The hot plate was set at 35 ° C, 80 ° C, 100 ° C, 150 ° C, 200 ° C in seven steps.
The substrate was sequentially moved to each plate at 90 ° C., 140 ° C., and 70 ° C. for 90 seconds and heated. Finally, heating and curing are performed in a clean oven (manufactured by Tabai) at 200 ° C. for 1 hour. It was confirmed that the color filter produced by this method had no optical unevenness. Next, in order to confirm that the liquid crystal aligning ability can be imparted to the OC film, the above-mentioned OC material liquid is spin-coated on two glass substrates with ITO transparent electrodes, and heated at 70 ° C. for 1 minute to evaporate the solvent. O on the substrate
After forming the C resin film, the film was cured by heating at 200 ° C. for 1 hour in an oven. Next, the pushing amount is 0.4 mm, the roller rotation speed is 400 rpm, and the table moving speed is 600 mm /
The OC resin coated surface was rubbed 10 times under the condition of min. The substrate was ultrasonically cleaned in pure water at 60 ° C. and dried in an oven at 170 ° C. for 10 minutes. Next, the two substrates are combined with the OC resin coating layers facing each other so that the rubbing directions are antiparallel, and the periphery is sealed with a thermosetting sealant, and the test space is set so that the gap is about 5 μm. The cell was assembled and heated in an oven at 150 ° C. for 1 hour to cure the sealant. A liquid crystal Z made by Merck was added to this test empty cell.
LI-4792 (trade name) was sealed at room temperature to form a liquid crystal cell. The liquid crystal cell was observed through a polarizing plate to evaluate the orientation of the liquid crystal. As a result, a favorable liquid crystal orientation was uniformly exhibited in one direction. Further, the liquid crystal cell was placed in an oven for 130 minutes.
Aging treatment was performed by heating at 1 ° C. for 1 hour and then gradually cooling, and the liquid crystal alignment was evaluated again. As a result, even after the aging, good liquid crystal alignment was uniformly obtained in one direction. For the purpose of measuring the transmittance of the OC material serving as an alignment film, a three-dimensional crosslinked resin precursor solution is applied onto a quartz glass substrate at 3000 rpm, 3 rpm.
Coated by spin coating under the condition of 0 second, dried at 70 ° C. for 1 minute using a hot plate,
After curing for 5 minutes, a transparent resin film was obtained. The absorption spectrum of this substrate was measured using a visible / ultraviolet spectrophotometer (U
As a result, almost no absorption was observed in the visible light region. The transmittance at a wavelength of 400 nm was determined as follows. The absorbance of the resin coating portion was calculated by subtracting the absorbance of the quartz glass substrate alone, which was separately measured from the absorbance of the quartz glass substrate provided with the resin coating, to be 0.0078. Next, a part of this resin film was cut off, and a contact-type film thickness meter (Dektak3) was removed.
030), the film thickness was 828 nm. The transmittance at a film thickness of 0.5 μm calculated from these results was 99%.

[0011]

According to the present invention, a color filter having liquid crystal alignment ability can be manufactured. Further, since the liquid crystal alignment film of the present invention is a three-dimensional crosslinked product and is not a polyimide resin conventionally used for an alignment film, it has high transparency and can easily form a thick film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display.

[Description of Signs] 1 BM (black matrix) 2 glass substrate 3 color pixel 4 protective film (overcoat layer, OC) 5 polarizing plate 6 ITO electrode 7 color filter 8 alignment film 9 liquid crystal 10 sealing material 11 top coat layer 12 ITO Electrode 13 Glass substrate 14 Polarizer 15 G pixel 16 Chromium film 17 B pixel

Claims (4)

[Claims] 1. A color filter comprising a transparent substrate, a predetermined pixel group formed on the transparent substrate, and a protective film formed on the predetermined pixel group, wherein the protective film has a liquid crystal alignment ability. A color filter characterized by the following. 2. The color filter according to claim 1, wherein the protective film is a three-dimensionally crosslinked resin. 3. The color filter according to claim 1, wherein the alignment film is a film provided with a liquid crystal alignment ability by rubbing. 4. An alignment film having a transmittance in the range of a wavelength of 400 nm or more and 800 nm or less when converted to a film thickness of 0.5 μm.
The color according to any one of claims 1 to 3, which is a film having a percentage of
filter.