JPH10319227A - Manufacturing method of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a color filter excellent in the surface flatness of the filter layer and ensuring satisfactory image quality by forming an ink coating film on the surface of a transparent substrate, curing only the surface of the film and flattening the film. SOLUTION: An ink coating film 1 is formed on a transparent substrate 2 by printing with colored inks in accordance with the colors of a filter layer. Only the surface of the film 1 is cured and the film 1 is flattened, dried by heating and perfectly cured to obtain the objective color filter. The degree of surface curing of the ink coating film 1 is set in accordance with the compsn. and viscosity of the film 1, the affinity of a roll 3, a sheet, etc., used for flattening the film 1 for the film 1, etc. Only the surface of the film 1 is cured by heating the film 1 while regulating heating temp. and time so that the film 1 is not perfectly cured.

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 for a liquid crystal color display or the like.

[0002]

2. Description of the Related Art A liquid crystal color display used as a display device in place of a cathode ray tube or the like realizes color display using a color filter. This color filter is formed by forming a patterned filter layer of three colors of red (R), green (G) and blue (B) on a transparent substrate.

In a liquid crystal panel of a liquid crystal color display, a transparent electrode (ITO film) is provided on the surface of a color filter.
Is formed, and a liquid crystal layer is formed on the surface. However, if fine irregularities exist on the surface of the filter layer, ITO
Problems such as disconnection due to insufficient coating of the film and unevenness in image display due to uneven thickness of the liquid crystal layer occur. In addition, there is also a problem that light is diffused due to unevenness on the surface of the filter layer, and light transmittance of the color filter is reduced. For this reason, the surface of the color filter is required to be formed extremely flat.

Conventionally, a photolithography method has been used for manufacturing a color filter. However, this method requires a large amount of expensive photoresist and expensive manufacturing equipment such as a spin coater line. There was a problem that the cost was high. Therefore, in recent years, it has been studied to reduce the cost of the color filter by using a printing method that is simple in manufacturing process and excellent in mass productivity.

[0005]

According to the printing method, red
(R), green (G) and blue (B) inks of three colors are printed on a transparent substrate, and the resulting ink film is heated and dried to form a filter layer. However, the ink coating film 1 formed on the surface of the transparent substrate 2 by the printing method has
As shown in the cross-section of FIG. 1, the red ink coating 1R, the green ink 1G, and the blue ink 1B are raised for each color, and the entire surface of the ink coating 1 is uneven. Therefore, in order to put the color filter obtained by the printing method into practical use, it is necessary to apply a flattening treatment to the surface of the ink coating film 1.

Since it is difficult to deform the ink coating once it has been cured, the filter layer must be flattened before the ink coating is cured and loses its viscosity. However, when pressure is applied to the uncured ink film with a roller or the like, the shape of the ink film formed by printing may be unnecessarily crushed, causing a problem such as deterioration of the pattern shape such as loss of linearity of the pattern. This may cause a problem that the ink is peeled off and adheres to a roller or the like, resulting in an insufficient ink film thickness, or rather, an uneven surface.

On the other hand, there has been proposed a method of flattening ink using a roller whose surface is made of a material having a low surface energy such as silicone, or through a sheet or the like made of a material having a low surface energy. However, the effect of preventing ink from adhering to rollers, sheets and the like is insufficient. In addition, although it is necessary to perform the flattening treatment of the ink coating film in an uncured state in which the ink maintains viscosity, dust such as dust in the air easily adheres to the surface of the ink film in this state. As a result, the image quality of the color filter deteriorates, so that it is necessary to consider handling and storage methods.

Therefore, there is a need for a method capable of flattening the surface while preventing deterioration of the pattern shape and peeling of the ink, and preventing adhesion of dust to the surface of the ink coating film. An object of the present invention is to provide a method for manufacturing a color filter having excellent flatness of the surface of a filter layer and good image quality.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, after forming an ink film on the surface of a transparent substrate, only the surface of the ink film has been removed. When hardening and then flattening, the inventors have found a new fact that a color filter having excellent image quality and excellent surface flatness of the filter layer can be obtained, and the present invention has been completed.

According to the present invention, the surface portion of the ink film is hardened and loses viscosity during the flattening process.
There is no deterioration of the shape of the pattern and no peeling of the ink. On the other hand, since the inside of the ink film is not cured and has sufficient viscosity, it can be flattened by applying pressure with a roller or the like. Also, since the surface of the ink film loses viscosity, dust such as dust in the air adheres to the surface of the ink film before the ink film is completely cured after the flattening process. Can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, first, an ink colored according to the color of a filter layer is printed on a transparent substrate to form an ink coating film. Next, after only the surface of the ink film is cured, the ink film is subjected to a flattening process. After the flattening process, the color filter is obtained by heating and drying the ink coating to completely cure it.

In the method of manufacturing a color filter according to the present invention, the degree of curing of the surface of the ink coating when the ink coating is subjected to the flattening treatment includes the composition of the ink coating, the viscosity of the ink coating, and the leveling treatment. It is set according to the affinity between the roller and sheet used for the ink and the ink coating film. In general, it is sufficient that the ink has lost its tackiness to such an extent that the ink does not adhere to a roller or a sheet used for the flattening process.

To cure only the surface of the ink coating,
Heating may be performed by adjusting the heating temperature and the heating time so that the ink coating film is not completely cured. As a method of heating the ink coating film, for example, (1) blowing with a flame, (2) infrared rays (I
R) irradiating a lamp, (3) irradiating an ultraviolet (UV) lamp, and (4) blowing hot air. Hereinafter, each method will be described in detail.

(1) Blowing with a flame This method is a method in which an ink coating film formed on a transparent substrate is heated by a long flame over a flame such as a burner. As the burner, for example, a gas burner such as propane, butane, and acetylene can be used. The heating conditions of the ink film, such as the type of gas burner to be used, the temperature of the flame, the distance from the crater of the burner to the ink film, the time of spraying with the flame, etc., depend on the composition of the ink film, the thickness of the film, etc. Is set. Accordingly, the heating conditions of the ink coating film are not particularly limited, but generally, the surface temperature of the ink coating film during the heat treatment is 100 to 200 ° C., and the heating time is one transparent substrate (360 mm). (About 460 mm) is set to about 5 to 60 seconds.

When this method is used, there is obtained a secondary effect such that dusts such as dust adhering during a period from immediately after the ink coating film is formed by printing until only the surface thereof is cured can be incinerated and removed. (2) Irradiation with an infrared (IR) lamp This method is a method of irradiating an ink film formed on a transparent substrate with an infrared lamp to heat it. That is, since the ink is cured by heat generated by the irradiation of infrared rays, the resin forming the ink coating film does not need to be an infrared curable resin.

The types of infrared lamps include far infrared rays,
Various things such as near infrared rays can be used. The heating conditions of the ink coating such as the intensity of infrared rays and the irradiation time are adjusted by the composition of the ink coating, the thickness of the coating, and the like, as described above. The surface temperature and heating time of the ink coating film during the heat treatment are not particularly limited, but are generally set in the same range as described above.

(3) Irradiation with an ultraviolet (UV) lamp This method is a method of irradiating an ink film formed on a transparent substrate with an ultraviolet lamp to heat it. This method also
Since the ultraviolet lamp is simply used as a heat source in the same manner as the infrared irradiation, the resin forming the ink coating film does not need to be an ultraviolet curable resin.

Various types of ultraviolet lamps such as a low-pressure mercury lamp and a high-pressure mercury lamp can be used. The heating conditions of the ink coating such as the intensity of the ultraviolet light and the irradiation time are adjusted by the composition of the ink coating, the thickness of the coating, and the like, as described above. The surface temperature and heating time of the ink coating film during the heat treatment are not particularly limited, but are generally set in the same range as described above.

(4) Blowing hot air This method is a method in which hot air (or hot air) is blown onto the ink coating film formed on the transparent substrate and heated. The speed of blowing the hot air is not particularly limited, but it is necessary to adjust so that the shape of the ink coating film does not change due to the pressure of the hot air.

The heating conditions of the ink coating, such as the temperature of the hot air and the time for blowing the hot air, are adjusted by the composition of the ink coating, the thickness of the coating, and the like, as described above. The surface temperature and heating time of the ink coating film during the heat treatment are not particularly limited, but are generally set in the same range as described above. In the present invention, as a method of flattening the ink coating film, for example, as shown in FIG. 2, a method of pressing the surface of the ink coating film 1 formed on the surface of the transparent substrate 2 with the roller 3 or a method of FIG. As shown in the figure, through the flat sheet 4,
A method of pressing the surface of the ink coating film 1 with the roller 3 may be used.

The above rollers, sheets and the like preferably have low surface energy in order to completely remove the possibility that ink adheres to the surface. Therefore, silicone rubber, fluororesin, or the like is used on the surface of the roller, sheet, or the like. The roller may be made of a metal such as stainless steel, iron, or aluminum. In this case, a roller whose surface is plated and a roller whose surface is flattened by polishing are preferable. Further, the roller may be made of ceramics. In this case, it is preferable that the surface of the roller is made of metal, and that the surface of the roller is flattened by polishing.

When pressure is applied by the above rollers, it is necessary that a constant load is always applied to the ink coating film. Therefore,
For example, a mechanism such as an air cylinder at a location that holds both ends of the roller so that the roller can follow fine irregularities, warpage, deflection on the surface of the transparent substrate, or deflection, blurring, etc. of the base that holds the transparent substrate. Is preferably provided. As a degree of the flattening treatment of the ink film, there is a method of evaluating the surface roughness (for example, ten-point average roughness R _Z ) of the ink film. Usually, the surface of the ink coating has a ten-point average roughness R _Z (J
ISB 0601) may be in the range of 0.01 to 0.15, preferably 0.01 to 0.10 μm.

The ink used in the present invention is a vehicle containing a binder resin and a pigment. As the binder resin, those having excellent properties such as transparency, heat resistance, light resistance, solvent resistance, chemical resistance, adhesion to a transparent substrate, and dispersibility of a pigment are preferable.For example, polyester-melamine Resins, melamine resins, epoxy resins, epoxy-melamine resins, and the like. These resins are used alone or in combination of two or more. Further, a curing catalyst such as an acid catalyst may be appropriately contained in the resin for the purpose of adjusting the curing speed of the resin.

The pigment is appropriately selected from, for example, red pigments such as anthraquinone, green pigments such as halogenated phthalocyanine, and blue pigments such as phthalocyanine according to the desired color of the filter layer. To adjust the spectral characteristics of the color filter ink, yellow pigments such as isoindoline and isoindolinone are used in red and green inks, and violet pigments such as dioxazine are used in blue inks. May be.

The mixing ratio of the pigment to the total weight of the ink is determined according to the pigment used, the spectral characteristics required of the ink, the printability of the ink, and the like. The viscosity of the ink is set in consideration of the mixing ratio of the pigment according to the spectral characteristics and the printability. For example, when the ink of the present invention is used in an intaglio offset printing method, the viscosity of the ink is suitably set to 10 to 30,000 poise (P), preferably 500 to 10,000 poise. When the viscosity of the ink is out of the above range, adverse effects such as uneven scraping of the ink at the time of doctoring and disorder of the shape of the printed pattern may occur, and the printability may be deteriorated.

The transparent substrate used in the present invention preferably has a high transmittance for light having a wavelength of 400 to 700 nm. For example, glass substrates such as non-alkali glass, soda lime glass and low alkali glass, and polyether and polysulfone , Polyarylate and the like are preferably used. As the printing method used for the production of the color filter, there are usually a lithographic offset printing method without water and an intaglio offset printing method. From the viewpoint of the linearity of the printing line and the uniformity of the ink film thickness, etc. The method is preferably used.

In the intaglio offset printing method, printing is performed by filling the concave portions of the intaglio with a color filter ink, and then transferring the ink to the surface of the blanket, and then transferring the ink to the surface of the transparent substrate. Will be As the intaglio used for the printing, as the substrate, for example, soda lime glass, non-alkali glass,
Glasses such as quartz glass, low alkali glass, and low expansion glass; resins such as fluorine resin, polycarbonate resin, polyether sulfone resin, and polymethacrylic resin; and those using metals such as stainless steel, copper, and low expansion alloy invar. Can be Above all, it is preferable to use soft glass such as soda lime glass in order to reproduce a fine pattern with high accuracy.

The recesses of the intaglio are made according to the pattern of the filter layer. The depth of the recess is usually 1-1.
The thickness is set in the range of 5 μm, preferably 5 to 10 μm according to the thickness of the filter layer. Examples of the shape of the pattern include a stripe pattern. The width of the pattern (that is, the width of the concave portion) varies depending on the size of the color filter, but is generally set in the range of 5 to 70 μm, preferably 10 to 30 μm.

As the blanket used for the above printing, for example, silicone rubber, acrylonitrile-butadiene rubber (N
Conventionally known ones carrying a surface rubber layer made of rubber such as BR) are exemplified. Further, a porous sponge layer may be provided between the surface rubber layer and the support or on the back surface of the support. The foaming ratio and the like of the sponge layer are set in consideration of the printing characteristics of the blanket.

The surface rubber layer of the blanket preferably has a smooth surface in order to improve the flatness of the surface of the filter layer (ink coating film). For example, the surface roughness of the blanket is 0.5 μm or less, especially 0.3 μm
It is appropriate that: Also, as a surface rubber layer,
Ink hardness (JIS K 6253 _-1988 Shosai spring hardness H _S, JIS A) 20 to 80, when using the silicone rubber is particularly 40 to 60, the ink transfer is good, which is transferred from the intaglio Can be completely transferred to the surface of the transparent substrate. Further, since the ink is not divided between the blanket and the transparent substrate, there is an effect that the edge of the line becomes sharp. This effect is remarkable in printing a fine pattern having a pattern line width of 50 μm or less.

As the above-mentioned silicone rubber, for example, millable silicone rubber, RTV silicone rubber, electron beam-curable silicone rubber and the like can be used. Further, in order to adjust the hardness of the silicone rubber to the above range, silicone oil, silicone gel or the like may be appropriately blended.
As described above, the ink printed on the surface of the transparent substrate is cured only at its surface and subjected to a flattening process, and is further usually performed at 180 to 250 ° C. for 30 to 180 minutes, preferably at 200 to 230 ° C. Is completely cured by heating and drying for 50 to 80 minutes. Thus, a color filter in which the filter layer is formed on the surface of the transparent substrate is obtained.

[0032]

【Example】

(Formation of ink coating film) Mixing and stirring melamine-based thermosetting resin, coloring pigment and diethylene glycol monobutyl ether acetate (solvent), red (R), green (G)
And blue (B) color filter inks were prepared.
The ink of each color was adjusted to have a viscosity of about 1000 poise.

Next, the color filter inks of the above colors are used.
Using the intaglio offset printing method
Print ink in order, line width 100 μm, thickness 5 for each color
forming an ink coating consisting of a μm stripe pattern
Was. The above printing is performed using a standard flatbed printing machine,
Performed by the set printing method. The intaglio has a line width of 120 μm,
Non-aperture with recesses of 8 μm depth formed at 300 μm intervals
The thing made from Lucari glass was used. On the blanket,
Sumitomo Rubber Industries, Ltd. silicone blanket (thickness
1mm, silicone rubber spring hardness H _S(JIS
 A) 50 °) was used. Non-alkaline transparent substrate
Ligarth (Corning's model # 7059, thickness 1.
1 mm, 360 mm × 460 mm) was used.

Example 1 The surface of the ink coating obtained by the above-mentioned printing was heated with a butane gas burner (about 600 ° C.) to cure only the surface of the ink coating. . In the heat treatment, the distance between the crater and the ink coating was adjusted so that the flame did not directly contact the ink coating and the surface temperature of the ink coating was about 180 ° C. The heating time was about 60 seconds per transparent substrate.

After being heated by the gas burner, the ink coating was allowed to cool for 7 minutes, and the surface of the ink coating was flattened while being pressed with a metal roller at a weight of about 20 kg. In Example 1, the ink did not adhere to the surface of the roll, and the ink film could be sufficiently flattened. In addition, after the ink coating film was formed by printing, the dust attached before the surface was cured was burned and removed, and the adhesion of the dust after the ink coating surface was cured could be prevented.

Example 2 In the same manner as in Example 1 except that heating was performed using an infrared lamp instead of the gas burner, only the surface portion of the ink coating film was cured. A far-infrared lamp (output: 1000 kW) was used as the infrared lamp. In the heat treatment, the distance between the infrared lamp and the ink coating was adjusted so that the surface temperature of the ink coating was about 180 ° C. The heating time was about 30 seconds per transparent substrate.

After heating by the infrared lamp, the sample was allowed to cool for 7 minutes, and flattened in the same manner as in Example 1. In Example 2, the ink did not adhere to the surface of the roll, and the ink film could be sufficiently flattened. In addition, adhesion of dust after the ink film surface was cured was prevented.

Example 3 In the same manner as in Example 1 except that heating was performed using an ultraviolet lamp instead of the gas burner, only the surface portion of the ink coating film was cured. A low-pressure mercury lamp (output: 1000 kW) was used as the ultraviolet lamp. In the heat treatment, the distance between the ultraviolet lamp and the ink coating was adjusted so that the surface temperature of the ink coating was about 80 ° C. The heating time was about 120 seconds per transparent substrate.

After heating by an ultraviolet lamp, the substrate was allowed to cool for 7 minutes, and flattened in the same manner as in Example 1. In Example 3, the ink did not adhere to the surface of the roll, and the ink coating film could be flattened. Although the effect of flattening was lower than in Examples 1 and 2, no practical problem occurred. In addition, adhesion of dust after the ink film surface was cured was prevented.

Example 4 In the same manner as in Example 1 except that a heat treatment was performed using warm air instead of the gas burner, only the surface portion of the ink coating film was cured. In the heat treatment, the temperature of the hot air was set at about 220 ° C. The heating time was about 30 seconds per transparent substrate.

After heating with warm air, the sample was allowed to cool for 7 minutes, and flattened in the same manner as in Example 1. In Example 4, the ink did not adhere to the surface of the roll, and the ink film could be flattened. The effect of the flattening is described in Example 1.
However, there was no practical problem. In addition, adhesion of dust after the ink film surface was cured was prevented.

Comparative Example A flattening treatment was performed without curing the surface portion of the ink coating film. The operation of the flattening process was performed in the same manner as in Example 1. In Comparative Example 1, since the ink adhered to the surface of the roll, the ink coating film was insufficiently flattened. Therefore, the color filter obtained by completely curing the ink coating film was not suitable for practical use. Further, it was not possible to prevent dust from adhering to the surface of the ink coating film.

[0043]

As described in detail above, according to the present invention,
A color filter having excellent flatness of the surface of the filter layer and good image quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a cross section of an ink coating film formed by a printing method.

FIG. 2 is a schematic diagram illustrating an example of a flattening process of an ink coating film.

FIG. 3 is a schematic view showing another example of the flattening process of the ink coating film.

[Explanation of symbols]

 1 Ink coating 2 Transparent substrate 3 Roller

Claims (1)

[Claims] 1. A method for producing a color filter, comprising forming an ink coating on the surface of a transparent substrate, curing only the surface of the ink coating, and then flattening the surface.