JPH09189806A - Color filter and its production as well as liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide excellent color filters having decreased differences in surface level, a process for producing these color filters at a low cost and further a liquid panel including such color filters and having a high image grade. SOLUTION: The production of the color filters is executed by forming an ink absorptive resin layer in a substrate 1, forming selectively cured layers on the layer, forming prescribed colored sections by impartation of ink thereon and swelling the resin layer by the ink impartation to build up the surface of the resin layer and applying a light shielding resin 5 over the entire surface of the substrate. The light shielding resin 5 is cured and the surface of the substrate is removed by as much as prescribed depth by polishing, etc., to expose the colored parts, by which the plural pixels isolated by the light shielding parts from each other are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter and a method for manufacturing the same, and a liquid crystal display device using the filter, and more particularly to a color filter using an ink jet recording technology and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recent portable personal computers,
With the development of small LCD TVs and thin LCD color TVs, the demand for liquid crystal displays is increasing. Among them, the growth of liquid crystal displays for displaying color images is remarkable. A color liquid crystal display is composed of materials such as a liquid crystal composition, a switching element, a polarizing plate, an alignment film, a glass substrate and a color filter.

A color filter is composed of a plurality of coloring members (generally red, blue and green) having different light transmittances on a transparent substrate, and each coloring member functions as a pixel. A light-shielding member is provided between each pixel in order to increase the display contrast, and since this light-shielding member is generally black, it is called a black matrix. The black matrix may be provided on the side of the substrate that faces the color filter.

Usually, the black matrix is formed by subjecting a metal chromium deposition film or a sputtering film to etching treatment. In addition, a transparent conductive base film made of ITO or the like is formed on a transparent substrate made of glass or the like over almost the entire surface thereof, and a pixel portion is formed thereon by a pigment dispersion method or the like. A method of forming a black matrix by an electrodeposition method using an ITO film, a film made of a black photosensitive resin is formed on a transparent substrate made of glass or the like, and the resin film is patterned by a photolithography method to give a red, Examples include a method of forming a black matrix corresponding to the gap between the green and blue color filters.

Regarding the method for forming the coloring member constituting the pixel, a method using a photosensitive resin in which a pigment is dispersed; a method in which a dyeable resin layer is patterned and dyed by photolithography; an electrode on a substrate There is a method of patterning and electrodepositing a dye on the electrode; a method of using printing. Furthermore, there is a method using an inkjet method as a low-cost forming method.

[0006]

As compared with the conventional method for manufacturing a color filter, the method for manufacturing a color filter using the inkjet method has a short process and is advantageous in cost.

When the color filter is formed by the ink jet method, the color filters are generally formed by ejecting inks of three colors of RGB. However, at that time, the resin layer having ink absorbability (hereinafter,
When an ink receiving layer) is used as a layer to which ink is applied, the ink receiving layer is characterized by swelling, and a step is formed between the colored portion and the non-colored portion.

When a color filter having such a large surface step is used to assemble a liquid crystal panel, for example, there is a problem that the image quality is remarkably deteriorated. Specifically, in an active matrix liquid crystal panel, 0.3 μm
Hereinafter, particularly in a simple matrix liquid crystal panel, flatness of 0.1 μm or less is required.

Further, since the amount of swelling varies depending on the type and amount of the R, G, and B colorants, such a difference in level difference between the colors also contributes to a reduction in flatness and a reduction in image quality. .

To solve such a problem, there is a method of applying a flattening layer on the colored pixel portion to further reduce the step. However, if the original surface step is large, the flattening layer needs to be thickened or multilayered, so that there is a drawback that the transmittance is lowered.

Therefore, an object of the present invention is to solve these problems, to provide an excellent color filter having a small surface level difference, a method for producing the same at low cost, and a liquid crystal of high image quality equipped with the color filter. To provide a panel.

[0012]

According to the present invention, an ink-absorbing resin layer is formed on a translucent substrate; a selective curing region is formed in the resin layer; and the selective curing of the resin layer is performed. In a region excluding the region, a colored portion of a predetermined color is formed in a predetermined pattern by applying ink by an inkjet method, and the resin layer surface is raised by swelling due to the application of ink.
Light-shielding resin is applied over the entire surface of the substrate; the light-shielding resin is cured; the surface of the substrate is removed to a predetermined depth by a method such as polishing to expose the colored portions to shield light from each other. A method of manufacturing a color filter for forming a plurality of pixels separated by parts, a color filter manufactured by the method, and a color filter substrate provided with the color filter, and a counter substrate facing the filter substrate, Provided is a liquid crystal panel in which liquid crystal is sealed between both substrates.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a process chart showing the procedure of an example of the method for producing a color filter of the present invention.
1 is a substrate, 2 is a photo-curable ink receiving layer, 3 is a photomask, 4 is an inkjet head, 5 is a light-shielding resin (paint), 6 is a polishing film, and 7 is a pressure roller.

First, an ink receiving layer which can be cured by a selective curing treatment is provided on a transparent substrate (FIG. 1 (a)).

The translucent substrate used for the color filter of the present invention is not limited to a general glass substrate, but is limited to a glass substrate as long as it has necessary properties such as transparency and mechanical strength as a color filter. However, a substrate made of plastic or the like can also be adopted.

The material constituting the ink receiving layer that can be used in the present invention must be one that undergoes a crosslinking reaction upon irradiation with light, and is composed of a plurality of types containing at least one type of photosensitive monomer. It contains a copolymer obtained from a monomer and a photoreaction initiator.

An example of such a photosensitive monomer is N
-Methylol acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, N-
Methylol methacrylamide, N-methoxymethyl methacrylamide, N-ethoxymethyl methacrylamide, etc. can be mentioned, but not limited to them.
Other examples of monomers that can form the above copolymer include carboxyl group-containing vinyl monomers such as acrylic acid and methacrylic acid; hydroxymethyl methacrylate,
Vinyl-based monomers having a hydroxyl group such as hydroxyethyl methacrylate, hydroxymethyl acrylate and hydroxyethyl acrylate; amides such as isopropoxymethyl acrylamide, acrylamide and methacrylamide; acrylic acid ester such as methyl acrylate and ethyl acrylate; Methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; styrene compounds for styrene and α-methylstyrene; vinyl carboxylic acids such as vinyl acetate and vinyl propionate; acrylonitrile;
Examples thereof include, but are not limited to, amines such as allylamine and vinylamine.

Next, the photoreaction initiator is not particularly limited, but onium salts and halogenated triazine compounds are preferably used.

The blending amount of the photopolymerization initiator in the above composition is
The weight ratio to the resin is preferably 0.01 to 20%.

Next, the ink receiving layer is selectively hardened to selectively harden the region where the black matrix is provided (FIG. 1B).

Curing is preferably performed by light irradiation or a combination of light irradiation / heat treatment. Further, it is more desirable to form a cured region by performing heat treatment after performing exposure through a photomask.

Next, an ink jet head is used in the non-cured area to absorb the inks of the respective colors of R, G, and B for coloring, and at the same time, the ink receiving layer is expanded (FIG. 1 (c)).

Examples of the ink jet method include a method using thermal energy and a method using mechanical energy, and any method can be adopted as appropriate.

As the ink material to be used, those which can be used in the ink jet method can be appropriately adopted. The colorant of the ink is appropriately selected from various dyes or pigments, for example, one that fits the transmission spectrum required for each pixel of R, G, and B. Also,
A material having a property of swelling the ink receiving layer material used is desirable.

After that, the ink is dried and then heat-treated to completely cure the resin layer.

Next, a light-shielding resin is applied over the entire surface of the color filter substrate (FIG. 1 (d)). As a coating method at that time, a spin coating method, a roll coating method, a dip coating method, or the like can be used. Then, the light blocking resin is cured. In this curing, the entire surface may be cured by heat curing, light curing or the like.

Next, until the colored portion on the substrate is exposed from the light-shielding resin film and becomes a pixel having a prescribed area,
The light-shielding resin and the colored portion of the ink receiving layer are polished in such a manner that the surface is sufficiently flat (FIG. 1 (e)).
It is desirable that the light-shielding resin layer on all the pixels is completely removed by polishing, and the upper portion of the colored portion is also collectively polished until the exposed portion of the colored portion has an equal area regardless of the color. Examples include a method of using a buff or a polishing film as the polishing agent, but any method can be appropriately adopted.

In this way, a color filter having a very flat surface can be obtained (FIG. 1 (f)).

Further, in order to protect the surface of the color filter from a solvent or the like, a protective layer may be formed with a thermosetting resin or a photocurable resin.

FIG. 2 shows a cross section of an example of a TFT color liquid crystal panel incorporating a color filter according to the present invention. The form is not limited to the example shown in the figure.

A color liquid crystal panel is generally formed by combining a color filter substrate and a counter substrate and enclosing a liquid crystal compound. TFTs (not shown) and transparent pixel electrodes are formed in a matrix on the inner side of the other substrate of the liquid crystal panel. Also, inside the other board,
A color filter is installed at a position facing the pixel electrode so that RGB color materials are arranged, and a transparent counter electrode (common electrode) is formed on one surface of the color filter. Further, an alignment film is formed in the plane of both substrates, and rubbing the alignment film allows liquid crystal molecules to be aligned in a certain direction. A polarizing plate is adhered to the outside of each glass substrate, and the liquid crystal compound is filled in the gap (about 2 to 5 μm) between these glass substrates. As a backlight, a combination of a fluorescent lamp (not shown) and a scattering plate (not shown) is generally used, and a liquid crystal compound is displayed by functioning as an optical shutter for changing the transmittance of the backlight. I do.

[0033]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The present invention also includes those in which the constituent elements are changed or replaced with known techniques within the range in which the object of the present invention is achieved.

Example 1 A resin layer was formed by coating the following photosensitive resin composition made of an acrylic polymer on a surface-polished non-alkali glass (200 mm square, thickness 1.1 mm). .

Specifically, after coating the photosensitive resin composition with a spinner, a pre-baking treatment is performed at 90 ° C. for 20 minutes,
A photosensitive resin layer having a film thickness of 2 μm was formed.

Photosensitive Resin Composition Methyl Methacrylate 5.0 parts by weight Hydroxymethyl Methacrylate 3.0 parts by weight N-Methylolacrylamide 2.0 parts by weight Ternary Copolymer Triphenylsulfonium Triflate (Midori Kagaku TPS-105) ) 0.3 parts by weight Ethyl cellosolve 89.7 parts by weight.

Next, a part of the photosensitive resin layer was pattern-exposed through a photomask having an opening in a region where a black matrix was to be formed, and heat treatment was further performed on a hot plate at 120 ° C. for 1 minute. . Through this step, the resin layer was partially cured.

Next, ink of each color of RGB was ejected from the ink jet head to infiltrate the uncured portion with the ink for coloring and swelling the uncured portion. After forming the ink dots, the ink was dried at 90 ° C. for 20 minutes.
Subsequently, heat treatment was performed at 230 ° C. for 30 minutes to cure the resin composition layer.

As a result, the film thickness difference between the colored portion and the non-colored portion was about 1.2 μm.

Next, a black paint HITASOL LCD-BM (trade name, manufactured by Hitachi Powder Metallurgy Co., Ltd.) having a film thickness of 1.
It was applied to have a thickness of 5 μm and dried at 100 ° C. for 20 minutes.

Next, using a polishing tape (# 1000) using alumina powder as the polishing condition, the surface of the black resin and the colored portion were polished with a pressure roller at a pressure of ² kg / cm ² . In the polishing, the black resin on all pixels was completely removed, and the upper portion of the colored portion was also polished until the exposed portion of the colored portion had an equal area regardless of the color. The level difference on the surface of the color filter thus obtained is 0.1.
It was very small, 5 μm.

As described above, the color filter obtained in this example has a very small surface level difference, and since it is not necessary to use a flattening film, the flattening film does not reduce the transmittance.

Further, when an STN liquid crystal panel was manufactured and driven by using the color filter manufactured as described above, high-definition color display was possible.

Comparative Example 1 A photoresist OFPR-800 (trade name; manufactured by Tokyo Ohka Kogyo Co., Ltd.) was formed on a glass substrate so as to have a film thickness of 1 μm, and exposed through a photomask for a black matrix, After developing, 9
A resist pattern was formed by drying at 0 ° C. for 20 minutes.

Subsequently, Example 1 was formed on the resist pattern.
The same black paint as used in 1) was applied to a film thickness of 1 μm, dried at 100 ° C. for 20 minutes, and then immersed in an aqueous solution of sodium hydroxide to peel off the resist pattern. Was formed.

Then, the photosensitive resin composition used in Example 1 was applied so as to have a film thickness of 1 μm, and then at 90 ° C. for 20 minutes.
A prebaking treatment was performed for a minute.

Next, a part of the resin layer in the portion where the black matrix is formed is pattern-exposed through a photomask having an opening portion which is narrower than the width of the black matrix, and is further heat-treated on a hot plate at 120 ° C. for 1 minute. Then, the resin layer was partially cured.

Next, ink of each color of RGB is ejected from the ink jet head, the ink is infiltrated into the uncured portion to be colored, the ink is dried at 90 ° C. for 20 minutes, and then heat treated at 230 ° C. for 30 minutes. The composition layer was cured. The film thickness difference between the cured part and the uncured part at this point was about 0.9 μm.

Next, a two-part thermosetting resin composition Optomer SS-6688 (trade name; manufactured by Nippon Synthetic Rubber Co., Ltd.) was applied to a film thickness of 2 μm, and prebaked at 90 ° C. for 30 minutes. After that, heat treatment was performed at 200 ° C. for 30 minutes to cure the protective layer.

The unevenness on the surface of the color filter thus produced was 0.4 μm, and the surface step was noticeable.

[0051]

As described above, in the color filter manufacturing method of the present invention, the steps of filling the step of the ink absorbing portion and the step of forming the black matrix are one step, and therefore the steps are shortened. Since the black matrix that does not use metal can be formed favorably, the color filter can be obtained at low cost. Moreover, by adopting the polishing step, it is possible to obtain extremely excellent flatness, and the color filter by the inkjet method can be sufficiently applied to a simple matrix liquid crystal panel or the like.

[Brief description of the drawings]

FIG. 1 is a method 1 for manufacturing a color filter according to the present invention.
It is process drawing which shows the procedure of an example.

FIG. 2 is a schematic cross-sectional view of an example of a liquid crystal panel including the color filter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Photocurable ink receiving layer 3 Photomask 4 Inkjet head 5 Light-shielding resin or paint 6 Polishing film 7 Pressure roller

Front page continuation (72) Inventor Akiko Shioda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A resin layer having ink absorbability is formed on a translucent substrate; a selective curing region is formed in the resin layer; and an ink jet method is applied to a region of the resin layer excluding the selective curing region. By applying ink to form a colored portion of a predetermined color in a predetermined pattern and swelling by applying the ink to raise the surface of the resin layer; applying a light-shielding resin over the entire surface of the substrate; Hardening; A method of manufacturing a color filter, in which a plurality of pixels separated from each other by light-shielding portions are formed by removing a predetermined depth on the surface of the substrate to expose the colored portions. 2. The method according to claim 1, wherein the removal of the substrate upper layer portion is performed by polishing. 3. A color filter obtained by the method according to claim 1. 4. A liquid crystal panel comprising a color filter substrate having the color filter according to claim 3 and a counter substrate facing the filter substrate, wherein liquid crystals are sealed between both substrates.