JPH08171008A - Production of color filter - Google Patents

Abstract

PURPOSE: To provide a production method for obtaining a color filter excellent in heat resistance, chemical resistance, dimensional accuracy and the like with a simple process at a low cost and high yield. CONSTITUTION: A colored pattern having a prescribed color is formed by transferring a colored fixed film 2 from each dry film 4 having the fixed film 2 having different color of at least three kinds such as R, G, B on the projected plate surface of the prescribed pattern and further transferring the transferred colored film 2 on a transparent substrate 8. And the color filter is produced by repeating a series of the transfer process for each color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a color filter used in a flat panel display such as a liquid crystal display (display device).

[0002]

2. Description of the Related Art In recent years, flat panel displays have rapidly expanded their applications in the fields of portable personal computers, car navigation systems, televisions, game consoles, etc. due to their high image quality, thin shape and light weight. Among flat panel displays, liquid crystal displays, in particular, have been used in a wider range of areas, mainly in display devices of OA equipment, because of their light weight and low price.

By the way, a color filter is used in the colorization of a liquid crystal display without spontaneous color development, and a color is expressed by transmitting white light from a backlight through the color filter.

Generally, a color filter is constructed by providing a light-shielding layer called a black matrix and a colored layer on a glass substrate, and forming a transparent overcoat layer (protective film) and a transparent electrode in that order on the light-shielding layer. In the colored layer, each dye of R (Red), G (Green), and B (Blue) corresponds to each pixel electrode on the liquid crystal display panel in a one-to-one correspondence, such as mosaic arrangement, stripe arrangement, triangle arrangement, etc. Are arranged in a pattern. In order to form such a colored layer of a color filter, various methods such as a dyeing method, a pigment dispersion method, a printing method and an electrodeposition method have been conventionally used.

[0005]

However, as will be described in detail below, each of these methods has advantages and disadvantages, and there are still many points to be improved. It has problems such as poor quality and high cost.

The dyeing method has hitherto been the most commonly used method as a practical technique at a mass production level. It is used for natural proteins such as gelatin and fish glue, and synthetic resins such as polyacrylamide, polyvinyl alcohol and polyimide. Such a dyeable photosensitive material is coated on a glass substrate to form an organic base material layer, and after a photofabrication process of exposure and development to form a transparent pattern, it is immersed in a predetermined dye solution. Dyeing, and repeating this step for three colors of R, G, and B to form a colored layer.

According to this method, it is possible to obtain a color filter having excellent transmittance and spectral characteristics and a vivid color tone. However, not only the process such as dyeing and dye-resisting treatment is complicated, but also the color fading against temperature and humidity is caused. The colored layer has a drawback that it is poor in reliability in terms of heat resistance, chemical resistance, weather resistance and the like.

The pigment dispersion method is currently in widespread use.
It is mainly used for manufacturing color filters for FT (thin film transistor) driving type liquid crystal displays.
This method uses a stable pigment powder in place of a dye that easily fades, forms a dye layer by coating a glass substrate with a solution prepared by dispersing the pigment powder in a substrate such as polyimide, and then exposing, This is a method of performing the treatment (coating and fixing treatment) of forming a colored pattern through a developing process for each of the three colors of R, G and B. Here, for forming the colored pattern, two methods are practically used: a method of separately applying a photoresist on the pigment layer and a method of dispersing the pigment in the photoresist to make the dye layer itself photosensitive. Both of them are expected to be methods that are simpler in process and lower in cost than the dyeing method. The color filter obtained by this method is inferior to the dyeing method in terms of spectral characteristics such as brightness and color tone, but the pigment used
Since it does not fade even at 250 ° C, it has good stability and has the advantage that the resistance of the transparent electrode provided on the colored layer can be lowered.

However, in such a pigment dispersion method, since a spin coater is usually used to apply a pigment-dispersed paint, 90% or more of expensive paint is wasted, which is not only against cost reduction but also applied. There is a problem that it is very difficult to uniformly control the film thickness distribution by. In addition, the coating process takes a very long takt time of 30 seconds or more, and there is a problem that the glass substrate is damaged significantly and the yield is low.

The printing method is a method that uses a printing ink containing a coloring matter (pigment) and has the highest mass productivity and can reduce the manufacturing cost. Some printing methods such as screen printing, flexo printing and offset printing are available. The scheme is being tried.
In recent years, simplification of the process by simultaneous application of three colors, improvement in yield, and the like have been attempted, and a color filter excellent in heat resistance and weather resistance has been obtained.

However, in this method, since uncured and highly fluid ink is used, not only is there a difficulty in cutting the edges (edge blurring, blurring, etc.), and the dimensional accuracy of the printed pattern is low. However, it is extremely difficult to cope with the miniaturization of pixels and the enlargement of display screens. Further, there is a problem that the printing surface has low smoothness, and defects such as pinholes and color unevenness are likely to occur due to mixing of dust and the like, resulting in poor yield.

The electrodeposition method is a method in which a dye (mainly a pigment) is ionized in an electrolytic solution and electrically adsorbed on an electrode pattern formed on the surface of a glass substrate, and a transparent electrode is used as an electrode for electrodeposition. (ITO) is used. This method has an advantage that it is not necessary to use a photolithography process having complicated steps for forming the colored layer, and the colored position and density can be controlled with high accuracy.

However, such an electrodeposition method has a drawback that it is difficult to form a black matrix. In addition, since the ITO film is double for the electrodeposition electrode and the electrode of the liquid crystal cell, not only the transmittance is lowered, but also in the dot matrix color filter, the resistance value of the lower electrode is limited due to the limitation of the ITO pattern. There are problems such as high cost and difficulty in manufacturing.

Further, as a method for forming a colored layer of a color filter, in addition to these methods, an ink jet method for forming a colored layer by ejecting ink with a probe and depositing it on a substrate is the same as a color printer. The method of coloring the dye by sublimation with heat, R, G,
Method of forming B pattern, method of forming color pattern by electrostatically coating pigment powder by electrophotographic method, dry film resist of R, G and B colors is directly laminated on a glass substrate and patterned by an exposure process. The film method and the like are newly developed and studied.

As described above, various methods have been proposed as a method for forming a colored layer of a color filter for a liquid crystal display or the like, but any of these methods is mass-producible,
There are problems in terms of manufacturing cost, takt time, defect countermeasures, yields, etc., and the current situation is that a method for completely satisfying the market demand has not yet been developed.

The present invention has been made in view of these circumstances, and solves the problem of poor yield and high manufacturing cost due to the complexity of the process, and the manufacturing process can be simplified and the cost can be reduced. Moreover, it is an object of the present invention to provide a method for manufacturing a color filter having excellent heat resistance, chemical resistance, dimensional accuracy, and the like.

[0017]

The method for producing a color filter according to the present invention is the method for producing a color filter, wherein a colored layer having at least two kinds of different color patterns is provided on a transparent substrate in a predetermined arrangement pattern. For each color, the solid colored pattern formed on the plate surface is transferred onto the transparent substrate to provide the arrangement pattern.

Further, in the method for producing a color filter in which a colored layer having at least three kinds of patterns of different colors is provided on a transparent substrate in a predetermined arrangement pattern, a resin composition in which a coloring material is dispersed for each color is used. After transferring the colored solidified film according to the pattern from the dry film having the colored solidified film as a main layer to the plate surface having a predetermined pattern, the colored solidified film transferred to the plate surface is further formed on the transparent substrate. It is characterized by transferring.

In the present invention, the colored pattern transferred from the plate surface to the transparent substrate is a pattern formed of a solid or solid colored film which does not easily change its shape or volume by an external force at room temperature. A colored solidified film transferred from the film to the plate surface is used. Needless to say, the above-mentioned colored film includes a substantially non-flowing film in which a part of the solvent component remains in a dried state.

As the main layer of the dry film, for example, a film having a solid or gel colored film made of a resin composition in which a pigment is dispersed is used. Usually, this film is obtained by applying a pigment-dispersed coating on a base film, applying a necessary treatment such as drying or curing, and then applying a cover film thereon, if desired.

Here, as a base film which is a base material of the dry film, polyethylene terephthalate (P
ET), polyphenylene sulfide (PPS), polyethylene (PE), polypropylene (PP), polyimide (PI), or other plastic film, metal foil, or a multilayer film obtained by laminating the above plastic film and metal foil. can do. In the present invention, it is particularly preferable to use a PET film having a thickness of 3 to 200 μm, but the material and the thickness are not limited as long as they meet the requirements required as the base material of the dry film. The film width is determined according to the size of the transparent substrate used, and the length is not particularly limited.

The pigment-dispersed coating material applied on such a base film is not particularly limited as long as it has been developed and used for forming a colored layer of a color filter. For example, it is preferable to use a paint in which pigments of R, G, and B colors are dispersed in a vinyl acetate-based or acrylic-based resin solution, respectively. Although not particularly required, the coating composition itself may be provided with photosensitivity, if necessary.

Further, as a coating method of such a pigment dispersion type coating material, a reverse coating method, a gravure coating method, a micro gravure coating method, a bar coating method, a wire bar coating method, a gap coating method, a knife coating method, a nozzle coating are provided. Various methods such as a method, a curtain coating method, a spray coating method, and an aero coating method are exemplified, and any coating method may be used as long as the thickness required for the colored layer is secured. Particularly in the present invention, a micro gravure coating method and a nozzle coating method, which are excellent in thin film properties and mass productivity, are suitable.

Further, as a cover film to be applied on the coating film of such a paint as required, PET,
Plastic films such as PPS, PE, PP, PI can be used. In particular, it is preferable to use a PE or PP film having a thickness of 3 to 50 μm, but the material and thickness are not particularly limited as long as they meet the requirements required as a cover film. The film width and length are determined according to the size of the base film used.

In the present invention, it is desirable to use, as the plate surface to which the colored solidified film of the above-mentioned dry film is transferred, a relief plate surface having a convex relief pattern corresponding to the array pattern of each color. Is not particularly limited to a flat plate surface, a curved surface, a roll surface, or the like. Further, the transfer of the colored solidified film from the dry film onto the pattern on the plate surface is performed by heating the surface of the plate to 50 to 200 ° C. to soften or partially melt the colored solidified film. Is also good. Further, the transfer from the plate surface to the transparent substrate can also be performed by heating similarly.

The transparent substrate is not particularly limited, but it is desirable to use a glass substrate from the viewpoint of transparency, durability, strength, etc., and it is usually used as a glass substrate for liquid crystal displays. 7059 from Corning
An example is NA45 manufactured by NH Techno Glass. Further, in such a glass substrate, an adhesive layer may be formed in advance on the transfer surface in order to transfer the colored solidified film adhered to the plate surface more completely onto the transparent substrate.

Further, in the method for producing a color filter of the present invention, the black matrix is not an essential element, but it can be provided on the transparent substrate if necessary. As a forming method, a physical method such as an ordinary Cr sputtering method or vapor deposition method, a chemical method using a photosensitive resist, a method by printing, a dry film transfer, exposure,
It goes without saying that various methods such as a method of developing to obtain a pattern or a method of transferring a matrix pattern from a dry film can be used as in the case of forming the colored layer in the present invention.

[0028]

In the method for producing a color filter of the present invention, when a colored layer in which patterns of at least three different colors such as R, G and B are arranged in a predetermined shape is formed, a dry film is applied to the plate surface. Since the solid colored film transferred according to the pattern is further transferred onto the transparent substrate, the colored film adhered (adhered) to the plate surface is
It moves to the transparent substrate as it is without breaking in the thickness direction by an appropriate pressing force, and no fragments of the colored film remain on the plate surface. Therefore, the deformation of the edge of the colored layer, the distortion of the pattern shape, and the like, which have been problems in the conventional printing method using a fluid ink, are eliminated, and the dimensional accuracy is improved and the yield is increased.

Further, according to the method of the present invention, the number of liquid treatment steps (wet step) including the photofabrication process of development and exposure and the cleaning process is small, and the number of steps requiring heat treatment is also shortened. Excellent mass productivity and low cost are also realized. Further, the damage to the substrate is small, the occurrence of defects is suppressed, and the number of steps is small and the tact time can be significantly shortened. Furthermore, regarding the utilization efficiency of the colored solidified film in the dry film, a high utilization efficiency of 90% or more can be achieved by controlling the shift amount of the plate.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

Example First, dry films for R, G and B were prepared respectively. That is, as shown in FIG. 1 (a), a pigment-dispersed coating material is applied to a base film (100 μm-thick PET film) 1 with a microgravure coater to a thickness of 1.8 μm, and then dried and cured. 1B, a cover film (PE film having a thickness of 20 μm) 3 is adhered onto the colored coating film 2 to form a dry film 4 for R as shown in FIG. 1 (b). Obtained. Similarly, a dry film for G and a dry film for B were produced.

Next, as shown in FIG. 2A, the colored coating film 2 was transferred from the R dry film 4 to the relief printing surface 6 of the principal surface of the prismatic relief printing 5.

That is, the letterpress surface 6 on which a dot-shaped pattern as shown in FIG. 3 is formed as a relief (convex portion) 7 having a height of 5 μm is pressed against the colored coating film 2 of the R dry film 4. The colored coating film 2 was transferred onto the convex portion 7. Then, as shown in FIG. 2B, a sputtering method or the like is performed in advance.
The letterpress surface 6 is pressed against the main surface of the glass substrate (7059 by Corning Inc.) 8 on which the black matrix of Cr is formed,
The colored coating film 2 transferred to the relief surface 6 was further transferred onto the glass substrate 8 to form an R color colored dot pattern. Further, after similarly forming dot patterns for each of G and B, baking (post-baking) is performed to complete a colored layer in which three colors of R, G, and B are arranged in a mosaic pattern. .

With respect to the color filters thus obtained, the utilization efficiency and yield of the colored coating film 2 in the base film 1 and the dimensional accuracy of the colored layer were examined.

Then, a TFT-driving liquid crystal display element was manufactured using the color filter obtained in this example. That is, an overcoat layer of acrylic resin or the like is provided on the colored layer of this color filter by a spin coating method,
After further flattening treatment, an ITO film was formed by a sputtering method and further subjected to alignment treatment to obtain a front side substrate of the liquid crystal display element. This was arranged so as to face a TFT substrate (not shown) to which a TFT driving element, an image electrode and the like were attached, and a liquid crystal composition was sandwiched between these substrates to obtain a liquid crystal display element. When a test pattern was displayed on such a liquid crystal display element, defects such as white pinholes, color unevenness, and discoloration in the displayed image were not found, and it was confirmed that good display was realized.

Next, for comparison, a dot matrix type color filter for TFT-LCD was manufactured by the following three methods.

Comparative Example 1 (Pigment Dispersion Method) First, regarding R, a pigment resist (pigment dispersion type resist) was applied onto a glass substrate using a bar coater, dried (prebaked), and then exposed, developed and washed. After performing a photolithography process, baking (post-baking) was performed to form a dot pattern of R color. Then G, B
Dot pattern for each color of
A color filter was produced. With respect to the color filter thus obtained, the utilization efficiency of the pigment-dispersed resist, the yield, and the dimensional accuracy of the colored layer were examined, respectively, and it was found that all were good, but inferior to the color filter obtained in this example. It was

Comparative Example 2 (Offset Printing Method) First, regarding R, the pigment resist ink held on the intaglio was transferred to the surface rubber layer of the blanket cylinder, then transferred from the blanket cylinder onto the glass substrate, and then baked to R. Dot pattern was formed. Dot patterns were similarly formed for each of the colors G and B to prepare color filters. With respect to the color filter thus obtained, the utilization efficiency of the pigment resist, the yield, and the dimensional accuracy of the colored layer were examined, respectively, the utilization efficiency of the resist is extremely good, equivalent to the color filter obtained in this example, The dimensional accuracy of the pattern of the obtained colored layer was poor, and the yield was low.

Comparative Example 3 (exposure using a dry film
Development Method First, using a photosensitive pigment resist, dry films for R, G, and B were prepared in the same manner as in this example. Next, the photosensitive resist of the dry film for R was transferred onto a glass substrate, subjected to a photolithography process of exposure, development and washing, and then baked to form a dot pattern of R color. Next, a dot pattern was similarly formed for each of the colors G and B to produce a color filter. The color filter thus obtained was examined for the utilization efficiency of the pigment resist, the yield, and the dimensional accuracy of the colored layer. It was found that all were good, but inferior to the color filter obtained in this example. In particular, the yield was significantly low.

[0040]

As is apparent from the above description, the manufacturing method of the present invention does not require a liquid processing step such as a photofabrication process such as development and exposure, a cleaning process, etc., and the number of steps is extremely small and simple. Has been converted. Therefore, according to the method of the present invention, problems such as poor yield and high cost due to the complexity of the process are solved, and heat resistance, chemical resistance, light resistance, etc. are excellent and dimensional accuracy is excellent. The color filter can be manufactured with high yield.

By using the color filter thus obtained, it is possible to provide a color flat panel display excellent in color characteristics and environment resistance, and particularly a liquid crystal display represented by a TFT system and an STN system. It is suitable for use as a color filter.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a process of manufacturing a dry film in an example of a method for manufacturing a color filter of the present invention.

FIG. 2 is a diagram for explaining a step of transferring a colored coating film from a dry film to a glass substrate through a relief surface in the same Example.

FIG. 3 is a diagram schematically showing a relief pattern formed on a relief printing plate in the example.

[Explanation of symbols]

 1 ... Base film 2 ... Colored coating film 3 ... Cover film 4 ... Dry film 6 ... Letterpress surface 8 ... Glass substrate

Claims (3)

[Claims] 1. A method of manufacturing a color filter in which a colored layer having at least two different color patterns is provided in a predetermined arrangement pattern on a transparent substrate, wherein a solid colored pattern formed on a plate surface is formed for each color. A method for manufacturing a color filter, which comprises transferring to a transparent substrate to provide the arrangement pattern. 2. A method of manufacturing a color filter, wherein a colored layer having a pattern of at least three different colors is provided in a predetermined arrangement pattern on a transparent substrate, the method comprising a resin composition in which a coloring material is dispersed for each color. After transferring the colored solidified film according to the pattern from the dry film having the colored solidified film as a main layer to the plate surface having a predetermined pattern, the colored solidified film transferred to the plate surface is further formed on the transparent substrate. A method for manufacturing a color filter, which is characterized by transferring. 3. The method for producing a color filter according to claim 1, wherein the plate surface is a plate surface having a relief pattern, and the colored solidified film is transferred onto the relief plate.