JP2003029020A - Color filter and method for manufacturing the same, liquid crystal element using the color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent color mixing, a bright defect and color irregularity inside a coloring pixel in a method for manufacturing a color filter with an inkjet method. SOLUTION: In the method for manufacturing the color filter comprising pattern exposure of an ink receiving layer composed of a photosensitive resin composition to form a part not to be colored and a part to be colored and imparting of ink to the part to be colored with the inkjet method to form a coloring part, a preventive effect on the color mixing by the ink on the part not to be colored is improved by forming a black matrix on a substrate, pattern exposing as described, subsequently irradiating the ink receiving layer with an infrared ray and elevating temperature only of the region of the ink receiving layer overlapping the black matrix so as to lower the ink absorbing property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter which is a constituent member of a color liquid crystal display used in a color television, a personal computer, a pachinko game table, a car navigation system, a small television, and the like, and a manufacturing method thereof. The present invention relates to a liquid crystal element using a filter.

[0002]

2. Description of the Related Art In recent years, the development of personal computers,
Particularly, with the development of portable personal computers, the demand for liquid crystal displays, especially color liquid crystal displays, tends to increase. However, for further popularization, it is necessary to reduce the cost of liquid crystal displays, and in particular, there is an increasing demand for reducing the cost of color filters, which have a high cost weight. Conventionally, various manufacturing methods have been tried to meet the above-mentioned requirements while satisfying the required characteristics of the color filter, but a method that satisfies all the required characteristics has not yet been established. Each method will be described below.

The first method is a pigment dispersion method which has been used most often in recent years. In this method, a photosensitive resin layer in which a pigment is dispersed is formed on a substrate, and this is patterned to obtain a monochromatic image. Get the pattern and R
By repeating (red), G (green), and B (blue), three colored portions are formed.

The second method is a dyeing method. In the dyeing method, a water-soluble polymer material, which is a material for dyeing, is applied onto a substrate, and this is patterned into a desired shape by a photolithography process, and then the obtained pattern is dipped in a dyeing bath to be colored. Get the pattern. This process is R,
By repeating G and B, three colored portions are formed.

As another example of this dyeing method, JP-A-5-28 is known.
8913 discloses a process of forming a photosensitive layer on a substrate, performing pattern exposure of the photosensitive layer, and dyeing an unexposed portion, R,
A method of forming colored portions of three colors by repeating G and B is disclosed.

A third method is an electrodeposition method. In this method, a transparent electrode is patterned on a substrate, and the first color is electrodeposited by immersing it in an electrodeposition coating solution containing a pigment, a resin, an electrolytic solution and the like. This process is repeated for R, G, and B, and baked to obtain three colored portions.

The fourth method is a printing method, in which a pigment is dispersed in a thermosetting resin, and printing is repeated three times.
After R, G, and B are separately coated, the resin is heat-cured to form a colored portion.

In any of the methods, it is general that a protective layer is formed on the colored portion, and the common point of these methods is that the colored portions of three colors of R, G and B are formed. Therefore, it is necessary to repeat the same process three times, which increases the cost. There is also a problem that the yield decreases as the number of processes increases. Further, in the electrodeposition method, since the pattern shape that can be formed is limited, it is difficult to apply the present technology to a TFT type (active matrix driving type using a thin film transistor for pixel switching) liquid crystal element. Further, the printing method is not suitable for forming a fine pitch pattern because of its poor resolution.

In order to make up for these drawbacks, JP-A-59-7 is used.
5205, JP-A-63-235901, JP-A-1-217302, and the like propose a method for manufacturing a color filter by an inkjet method. This method uses an inkjet recording device,
This is a method of forming colored portions by applying inks of R, G, and B colors on a substrate, and the colored portions of three colors can be formed in one step, and the amount of ink used is not wasted. Therefore, it is possible to significantly improve productivity and reduce costs.

[0010]

Specifically, as a method for producing a color filter by an ink jet method, specifically, a photosensitive resin composition layer whose ink absorbency is changed by light irradiation is formed on a substrate, and the resin composition layer is formed. Pattern exposure to
A colored portion having high ink absorbency and a non-colored portion having low ink absorbency are formed, and ink is applied and absorbed only on the colored portion to form the colored portion. In this case, the non-colored portion is an area for preventing so-called color mixing, in which inks of different colors are mixed between adjacent colored portions.

However, in the above method, if the ink absorbency of the portion to be colored is insufficient, the ink that has landed on the portion to be colored does not spread well in the portion to be colored, and the portion to be colored becomes uneven. There are cases in which there are uncolored or lightly colored portions due to coloring, and these are recognized as white spots or color unevenness. On the other hand, when the material of the ink receiving layer is changed to enhance the ink absorbency of the portion to be colored, the ink easily spreads even in the non-colored portion made of the same material, and color mixing easily occurs.

An object of the present invention is, in the method for producing a color filter by the above-mentioned ink jet method, the ink is well spread and uniformly colored in the portion to be colored, while the ink is favorably repelled in the non-colored portion to mix the colors. Another object of the present invention is to provide a highly reliable color filter with high yield, and to provide a liquid crystal element for color display at a lower cost by using the color filter.

[0013]

A first aspect of the present invention is to provide a color filter having a light-shielding layer having a plurality of openings on a substrate and a colored layer having a plurality of colored portions of a plurality of colors. And a step of forming a light-shielding layer having a plurality of openings on a substrate, the ink absorptivity is changed by at least light irradiation to cover the light-shielding layer, and the ink absorptivity is lowered by heating. A step of forming an ink receiving layer comprising a photosensitive resin composition layer, and pattern-exposing the ink receiving layer to form a colored portion having high ink absorbability in at least a region overlapping the opening of the light shielding layer, And, a step of forming a non-colored portion having a lower ink absorbability than the colored portion between adjacent colored portions of at least a part of the region overlapping the light shielding layer, and irradiating the ink receiving layer with infrared rays, Overlaps the light shielding layer At least the step of reducing the ink absorbency of the ink receiving layer in the area, and applying the ink to the colored portion of the ink receiving layer according to a predetermined coloring pattern by an inkjet method to form a colored portion. A method of manufacturing a color filter, which comprises:

In the method for producing a color filter of the present invention, the infrared rays with which the ink receiving layer is irradiated are preferably near infrared rays or mid infrared rays.

A second aspect of the present invention comprises a light-shielding layer having a plurality of openings on a substrate, and a colored layer having a plurality of colored portions of a plurality of colors for each color. A third feature is a color filter manufactured by, a third feature is that a liquid crystal is sandwiched between a pair of substrates, and one of the substrates is formed using the color filter of the present invention. It is a liquid crystal element that operates.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a method for producing a color filter by the above-mentioned ink jet method, in which the infrared ray absorbing property of a light shielding layer which is usually used is utilized to irradiate the ink receiving layer with infrared rays to form a light shielding layer. It is characterized in that the overlapping region is selectively heated to a high temperature to reduce the ink absorption. In the non-colored portion according to the present invention, the difference in ink absorbency between the portion to be colored and the portion to be colored is significantly increased by the pattern exposure and the heating by the infrared irradiation, and thus the ink is favorably repelled to prevent color mixture. can do. On the other hand, since the portion to be colored does not reach a high temperature even when irradiated with infrared rays, the ink absorbency hardly changes, and the ink is favorably absorbed and diffused to form a uniform colored portion.

Hereinafter, the method for manufacturing the color filter of the present invention will be described with reference to embodiments.

FIG. 1 is a process chart showing a preferred embodiment of the method for producing a color filter of the present invention, which is an example in which the ink receiving layer is formed of a negative photosensitive resin composition. In the figure, 1 is a substrate, 2 is a black matrix, 3 is an ink receiving layer, 4 is a photomask, 5 is a non-colored portion, 6 is a colored portion, 7 is ink, 8 is a colored portion, and 9 is a protective layer. . Each step will be described below, but (a) to (e) of FIG. 3 are schematic cross-sectional views corresponding to the following steps (a) to (e), respectively.

Step (a) The black matrix 2 is formed on the substrate 1. Board 1
As the material, a transparent substrate such as a glass substrate is generally used, but a transparent plastic substrate can also be used as long as it does not impair the transparency of the color filter and has necessary properties such as strength. The black matrix 2 may be a black stripe as described above, and its film thickness is usually about 0.1 to 0.5 μm. A metal such as chromium is formed on the substrate 1 by sputtering or vapor deposition, and photolithography is performed. It is obtained by patterning in the process. Further, the black matrix 2 may be formed by using a black resin or the like.

Next, an ink receiving layer 3 made of a photosensitive resin composition is formed on the entire surface of the substrate 1. Ink receiving layer 3
Is a coloring medium for coloring to form the colored portion 8 in a step described later, and is a photosensitive resin composition whose ink absorbency is changed by at least light irradiation and which is lowered by heating. . The photosensitivity may be either a negative type or a positive type, and specifically, a cellulose derivative such as an acrylic resin, an epoxy resin, a silicone resin, hydroxypropyl cellulose, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose or a modified product thereof. , Amide-based resin, phenol-based resin, polystyrene-based resin and the like are optionally used together with a photoinitiator (crosslinking agent). As the photoinitiator, a dichromate, a bisazide compound, a radical type initiator, a cationic type initiator, an anionic type initiator or the like can be used, and further, a mixture of these photoinitiators or other Can be used in combination with the sensitizer.
Furthermore, it is also possible to use a photoacid generator such as an onium salt as a crosslinking agent. The present embodiment shows an example using a negative resin composition whose ink absorbency is lowered by light irradiation.

The above photosensitive resin composition is spin coated,
It is applied on the substrate 1 by a method such as roll coating, bar coating, spray coating, or dip coating, and prebaked as necessary to form the ink receiving layer 3. Ink receiving layer 3
Usually has a thickness of about 0.3 to 3.0 μm.

Step (b) The ink receiving layer 3 is pattern-exposed using the photomask 4 to reduce the ink absorbency of the exposed portion and thereby the non-colored portion 5 is exposed.
To form. The area that has not been exposed in this step becomes the colored portion 6. The non-colored portion 5 is the black matrix 2
Is formed in a position overlapping with the black matrix 2.
From the viewpoint of preventing white spots at the boundary of the opening, it is preferable that the non-colored portion 5 is formed to be narrower than the width of the black matrix 2. The width of the non-colored portion 5 is 1.0 to 30.0 μm in consideration of the width of the black matrix of an ordinary color filter.

Further, since colored pixels of the same color (colored area in the opening of the black matrix 2) are arranged in the scanning direction of the ink jet head, the openings of the black matrix arranged in dots along the scanning direction. By forming the non-colored portions 5 in parallel stripes with respect to the partial rows so as to sandwich the opening row, stripe-shaped colored portions 6 parallel to the scanning direction are formed. It is preferable because the ink can be continuously discharged onto the portion to be colored 6.

When a positive type resin composition whose ink absorbency is increased by exposure is used, the pattern may be exposed in reverse.

Step (c) Irradiate infrared rays from at least one side of the substrate 1, preferably from both sides as shown in FIG. In the present invention, near-infrared rays or mid-infrared rays are preferably used as the infrared rays, and since the infrared rays are more highly absorbed by the black matrix 2, the temperature of the ink receiving layer in the region overlapping with the black matrix 2, mainly the temperature of the non-colored portion 5. Becomes higher, the ink absorbency of the area is further reduced, and the difference in ink absorbency between the colored portion 6 and the non-colored portion 5 becomes large.

The temperature of the area to be colored 6 that overlaps the black matrix 2 also rises due to the above infrared irradiation, but since the pattern exposure is not performed, the ink absorbency is not significantly reduced. Further, finally, the light is shielded by the black matrix 2 and is not involved in the display, so that the color filter is not substantially affected.

Step (d) The ink 7 of R, G and B is discharged from the ink jet head (not shown) along the predetermined coloring pattern onto the portion to be colored 6 for coloring.

The ink jet method used in the present invention is a bubble jet (registered trademark) type using an electrothermal converter as an energy generating element, or
A piezo jet type using a piezoelectric element or the like can be used, and the coloring area and coloring pattern can be set arbitrarily.

The ink 7 used for coloring the ink receiving layer 3 in the present invention may be either a dye type or a pigment type. Further, the ink is not limited to a liquid at normal temperature, and even an ink that solidifies at room temperature or lower, a liquid that softens at room temperature or a liquid, or the ink itself at 30 ° C. to 70 ° C. Since the temperature is generally controlled within the range to control the temperature of the ink so that the viscosity of the ink is in the stable discharge range, any liquid that is liquid at the time of discharge is preferably used.

Step (e) The entire ink receiving layer is cured by subjecting it to necessary treatment such as heat treatment or light irradiation to form a colored layer consisting of the non-colored portion 5 and the colored portion 8 and, if necessary, the colored layer. A protective layer 9 is formed on top to obtain the color filter of the present invention. As the protective layer 9, a photo-curing type, a thermosetting type, or a heat / light combined curing type resin composition layer, or an inorganic film formed by vapor deposition, sputtering or the like can be used. In any case, any material can be used as long as it has transparency as a color filter and can withstand the subsequent ITO film forming step, alignment film forming step and the like.

Next, FIG. 2 shows a schematic sectional view of an embodiment of the liquid crystal element of the present invention. The present embodiment is an example in which a TFT type color liquid crystal element is configured using the color filter of the present invention obtained by the process of FIG. In the figure, 10 is a common electrode, 11 is a counter substrate, 12 is a pixel electrode, 13 and 14 are alignment films, and 15 is a liquid crystal. The same members as those in FIG.

In the color liquid crystal element, generally, the substrate 1 on the color filter side and the counter substrate 11 are put together to form a liquid crystal 15
Is formed by encapsulating. TFTs (not shown) and pixel electrodes 12 are formed in a matrix on the inside of one substrate 11 of the liquid crystal element. Also, inside the substrate 1 on the color filter side, at a position facing the pixel electrode 12,
The colored portion 8 of the color filter is formed so that R, G, and B are arranged, and the transparent common electrode 10 is formed thereon. Furthermore, alignment films 13 and 14 are formed in the planes of both substrates, and liquid crystal molecules are arranged in a fixed direction. These substrates are arranged to face each other with a spacer (not shown) in between, and are bonded together by a sealant (not shown), and the liquid crystal 15 is filled in the gap.

In the case of a transmissive liquid crystal device, the substrate 11 and the pixel electrode 12 are made of a transparent material, and a polarizing plate is adhered to the outside of each substrate to generally combine a fluorescent lamp and a scattering plate. The display is performed by using a backlight and causing the liquid crystal compound to function as an optical shutter that changes the light transmittance of the backlight. In the case of a reflective type, the substrate 11 or the pixel electrode 12 is formed of a material having a reflection function, or a reflective layer is provided on the substrate 11 and a polarizing plate is provided outside the substrate 1, and a color filter is provided. Display is performed by reflecting the light incident from the side.

Further, in the liquid crystal element of the present invention, it goes without saying that the conventional technique can be used as it is for the other members as long as it is constructed by using the color filter of the present invention.

[0035]

Example 1 A black matrix having a plurality of openings of 80 μm × 210 μm arranged two-dimensionally was formed by sputtering a Cr film having a thickness of 0.15 μm and performing ordinary photolithography and etching processes. An acrylic resin-based photosensitive resin composition, which is mainly sensitive to Deep-UV light, was applied on the prepared glass substrate to a thickness of 1.0 μm by spin coating, and prebaked at 50 ° C. for 10 minutes. Performed to form an ink receiving layer.

Deep-UV is formed on the ink receiving layer through a photomask having a stripe-shaped opening having a width of 30 μm which is parallel to the longitudinal direction of the opening of the black matrix.
A pattern exposure of 50 mJ / cm ² was performed with light, and the arrangement of the openings of the black matrix in the longitudinal direction was used as opening rows to form parallel stripe-shaped non-colored portions and colored portions between the opening rows.

Then, 10 W / c is applied to the substrate from the front side.
After irradiating the near infrared ray of m ² for 150 seconds, the dye-based inks of R, G, and B were applied to the unexposed portion to be colored along a predetermined coloring pattern using an inkjet recording device. After confirming that the ink has sufficiently penetrated into the part to be colored,
Drying was performed at 10 ° C. for 10 minutes, and then post-baking treatment was performed at 200 ° C. for 1 hour to cure the entire ink receiving layer to obtain a color filter.

The obtained color filter has no color mixture between adjacent colored pixels of different colors (colored portions in the openings of the black matrix), there is no white spot or color unevenness in the colored pixels, and the surface flatness is good. Was excellent.

Further, a protective layer having a thickness of 2.0 μm was formed on the colored portion of the obtained color filter by using an acrylic thermosetting resin, and the surface was flat and the colored portion was protected. A good color filter was obtained.

Example 2 A color filter was produced in the same manner as in Example 1 except that the infrared ray with which the ink receiving layer was irradiated was changed to 8 W / cm ² . The obtained color filter had no color mixture as in Example 1, and there was no white spot or color unevenness in the colored pixel.

Further, a protective layer was formed on the colored portion of the obtained color filter in the same manner as in Example 1,
A good color filter having a flat surface and protected colored portions was obtained.

(Example 3) On a washed glass substrate,
A black resist (“V-259BK” manufactured by Nippon Steel Chemical Co., Ltd.) was applied by a spin coating method to a film thickness of 1 μm,
After prebaking at 10 ° C. for 10 minutes, using a matrix pattern mask, the black resist layer was exposed to UV light for 13 seconds through the mask, and spin-developed with an alkali developing solution. A black matrix having the same pattern as in Example 1 was formed.

On the above glass substrate, mainly Deep-UV
An acrylic resin-based photosensitive resin composition having sensitivity to light was applied by a spin coating method to a film thickness of 1.0 μm and prebaked at 50 ° C. for 10 minutes to form an ink receiving layer. The ink receiving layer is also formed on the black matrix with a thickness of about 0.6 μm.

The same pattern exposure as in Example 1 was performed on the above ink receiving layer to form parallel stripe-shaped colored portions and non-colored portions between the opening rows of the black matrix. Furthermore, after irradiating the ink receiving layer with near infrared rays of 8 W / cm ² for 150 seconds in the same manner as in Example 2,
Similar to Example 1, R, G, and B dye-based inks were applied to a portion to be colored along a predetermined coloring pattern, dried at 90 ° C. for 10 minutes, and post-baked at 200 ° C. for 1 hour. The entire ink receiving layer was cured to obtain a color filter.

In the obtained color filter, there was no color mixing between adjacent colored pixels of different colors, and neither white spots nor color unevenness was observed in the colored pixels.

Further, a protective layer was formed on the colored portion of the obtained color filter in the same manner as in Example 1,
A good color filter having a flat surface and protected colored portions was obtained.

[0047]

As described above, in the present invention, the high infrared absorptivity of the light-shielding layer is utilized to further reduce the ink absorptivity of the non-colored portion, so that the ink is repelled well in the non-colored portion. Thus, color mixture can be prevented, and at the same time, the colored portion can quickly absorb and diffuse the ink to form a colored portion without white spots or color unevenness. Therefore,
According to the present invention, a highly reliable color filter can be provided with a high yield by a simple process, and a liquid crystal element having excellent color display characteristics can be provided at a lower cost by using the color filter.

[Brief description of drawings]

FIG. 1 is a process drawing of a preferred embodiment of a method for manufacturing a color filter of the present invention.

FIG. 2 is a schematic sectional view of an embodiment of a liquid crystal element of the present invention.

[Explanation of symbols]

1 substrate 2 Black matrix 3 Ink receiving layer 4 photo mask 5 Non-colored part 6 Colored part 7 ink 8 Coloring part 9 Protective layer 10 Common electrode 11 Counter electrode 12 pixel electrodes 13, 14 Alignment film 15 LCD

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Claims (4)

[Claims] 1. A method of manufacturing a color filter comprising: a light-shielding layer having a plurality of openings on a substrate; and a coloring layer having a plurality of colored portions of a plurality of colors for each color. A step of forming a light-shielding layer having an opening, and an ink-receiving layer comprising a photosensitive resin composition layer covering the light-shielding layer, the ink absorbency of which is changed by at least light irradiation and which is lowered by heating. And a pattern exposure of the ink receiving layer to form a colored portion having high ink absorbability in at least a region overlapping with the opening of the light shielding layer, and at least one of regions overlapping with the light shielding layer. A non-colored portion having lower ink absorbability than the colored portion between adjacent colored portions, and irradiating the ink receiving layer with infrared rays to form an ink receiving layer in an area overlapping the light shielding layer. Ink absorption And a step of forming a colored portion by applying ink to the portion to be colored of the ink receiving layer according to a predetermined coloring pattern by an inkjet method to form a colored portion. Production method. 2. The method for producing a color filter according to claim 1, wherein the infrared rays with which the ink receiving layer is irradiated are near infrared rays or mid infrared rays. 3. The method of manufacturing a color filter according to claim 1, further comprising: a light-shielding layer having a plurality of openings on a substrate, and a coloring layer having a plurality of colored portions of a plurality of colors for each color. A color filter manufactured by. 4. A liquid crystal element comprising a pair of substrates and a liquid crystal sandwiched between the substrates, wherein one of the substrates is formed by using the color filter according to claim 3.