JP2001066413A - Color filter, its production method and liquid crystal device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a color filter free from irregular color of pixels due to the leaching and migration of each colorant. SOLUTION: An ink receiving layer 3 comprising a curable resin composition is formed on a transparent substrate 1 and a colorant-containing ink 4 is imparted to the ink receiving layer 3 by an ink jet system to color the ink receiving layer 3. The colored ink receiving layer 3 is heat-treated at >=200 deg.C to fix the colorant and the colarant is further chemically fixed by immersion in a dilute solution of a fixing agent.

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 component of a color liquid crystal display used for a color television, a personal computer and the like, a method of manufacturing the same, and a liquid crystal device using the color filter.

[0002]

2. Description of the Related Art A color filter is an important component of a color liquid crystal element. R (red), G (green),
It has a structure in which many pixels of three primary colors B (blue) are repeatedly arranged.

In recent years, with the development of personal computers, especially portable personal computers, the demand for liquid crystal displays, especially color liquid crystal displays, has been increasing. However, cost reduction is required for further widespread use, and in particular, there is an increasing demand for cost reduction of color filters having high specific gravity.

Conventionally, various manufacturing methods have been tried to satisfy the above requirements while satisfying the required characteristics of the color filter, but a method satisfying all the required characteristics has not yet been established. Hereinafter, a conventional method for manufacturing a typical color filter will be described.

The first method most frequently used is a pigment dispersion method. In this method, first, a photosensitive resin layer in which a pigment is dispersed is formed on a transparent substrate, and this is patterned to obtain a monochromatic pattern. In addition, this step
By repeating this process three times, three color filters of R, G, and B are formed.

[0006] The second most frequently used method is a dyeing method. The dyeing method uses a material obtained by adding a photosensitizer to a water-soluble polymer material that is a material for dyeing and sensitizing the same, and forming this into a pattern of a desired shape on a transparent substrate by a photolithography process, The obtained pattern is immersed in a dyeing bath to obtain a first colored pattern. By repeating this process three times, color filters of three colors of R, G, and B are formed.

A third method is an electrodeposition method. In this method, a transparent electrode is first patterned on a transparent substrate. Next, the first color is immersed in an electrodeposition coating solution containing a pigment, a resin, an electrolytic solution, and the like, and the first color is electrodeposited. Repeat this process three times,
A color filter of three colors of R, G, and B is obtained, and the color filter is finally obtained by baking.

A fourth method is a printing method. In this method, a paint in which a pigment is dispersed in a thermosetting resin is separately applied to three colors of R, G, and B by repeated printing, and then the resin that is a colored layer is heated and cured to form a color filter.

In each of the above methods, a protective layer is generally formed on the colored layer.

Common to these methods is that R,
In order to form three color layers of G and B, the same process is performed in three steps.
Times, which inevitably increases costs. There is also a problem that the yield decreases as the number of steps increases.

In addition, in the third electrodeposition method, since the pattern shape that can be formed is limited, the present technology cannot be applied to a TFT type (active matrix type using a TFT (thin film transistor)) color liquid crystal element. . Further, in the fourth printing method, there is a problem that resolution and smoothness are poor, and a fine pitch pattern cannot be formed.

As a method of solving the above problems, a method of manufacturing a color filter using an ink jet system has been proposed (JP-A-59-75205;
JP-A-3-235901, JP-A-1-217302, JP-A-4-123005). This method is different from the above-mentioned method in that an ink containing R, G, and B dyes is ejected from a nozzle onto a transparent substrate, and the ink is dried on the substrate to form pixels. According to this method, the formation of each of the R, G, and B colored layers can be performed in one step, and further, there is no waste in the amount of ink used. Can be planned.

[0013]

However, in the conventional method for producing a color filter by the ink jet method, the dye is not always fixed sufficiently, for example.
There have been problems such as color omission due to elution of the dye and color unevenness due to the movement of the dye within the pixel. For the immobilization of the dye, for example, for the dyeing method, after the relief pattern is dyed with the dye, a prescription of performing the immobilization by immersing in a solution of a fixing agent such as tannic acid is already known, but it is sufficient. In order to exhibit an effective fixing effect, heat treatment at a higher temperature is required.

However, in the dyeing method, the upper limit of the heat treatment at a high temperature is 180 ° C. in view of the thermal discoloration of the dye.
In fact, the fact is that a sufficient fixing treatment has not been performed.

An object of the present invention is to produce a highly reliable color filter with good productivity at a low cost, and to provide a liquid crystal element having excellent color display characteristics at a lower cost by using the color filter.

[0016]

A method of manufacturing a color filter according to the present invention is a method of manufacturing a color filter having a colored portion on a transparent substrate, wherein the ink receiving layer is formed of a curable resin composition on the transparent substrate. Forming an ink-containing layer by applying an ink containing a colorant to the ink-receiving layer by an ink-jet method;
And a step of performing a chemical treatment after heat treatment in an atmosphere of 00 ° C. or more to fix the coloring agent permeated into the ink receiving layer.

Further, the color filter of the present invention has a colored portion on a transparent substrate, and is manufactured by the above-described method of manufacturing a color filter of the present invention.

Further, the liquid crystal element of the present invention is characterized in that liquid crystal is held between a pair of substrates, and one of the substrates is formed using the color filter of the present invention.

The method for producing a color filter of the present invention is a method using an ink-jet method, and is particularly characterized in fixing a colorant (dye or pigment). As described above, in the manufacturing method using the inkjet method, it is required to fix the colorant contained in the ejected ink. Incomplete immobilization of the colorant causes elution of the dye from the color filter and unevenness in the pixel, resulting in a significant decrease in the quality and reliability of the color filter.

As a result of intensive studies, the present inventors have formed an ink receiving layer, applied an ink containing a colorant to the ink receiving layer and allowed the ink to permeate. By performing heat treatment in an atmosphere of 200 ° C. or higher, which was considered impossible, and further performing a chemical treatment, sufficient fixation of the colorant was realized, and elution of the colorant and color unevenness in the pixel were prevented. They have found that they can be suppressed and completed the present invention.

In the present invention, the reason why the thermal discoloration of the dye does not occur during the heat treatment at 200 ° C. or higher is not sufficiently understood, but unlike the present invention, the material for the relief pattern used in the dyeing method is different from the present invention. Cationic materials and heavy metals have been added to impart dyeing and photosensitivity,
It is considered that the dye had some effect at high temperature.

[0022]

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

FIG. 1 is a diagram showing the steps of an embodiment of the method for manufacturing a color filter of the present invention. In the figure, 1 is a transparent substrate, 2 is a black matrix, 3 is an ink receiving layer, 4
Is an ink, 5 is a colored portion, and 6 is a protective layer. 1A to 1E are schematic sectional views corresponding to the following steps (a) to (e), respectively.

Step (a) A black matrix 2 is formed on a transparent substrate 1 as required. When the black matrix 2 is formed directly on a substrate, a method of forming a metal thin film by sputtering or vapor deposition and patterning by a photolithography process is used. Examples include a patterning method using a general photolithography process, but the method is not limited thereto.

Step (b) The ink receiving layer 3 is formed on the transparent substrate 1. The ink receiving layer 3 can be formed by applying and curing a curable resin composition. As a material of such a resin composition, for example, considering heat resistance, an acrylic resin,
Epoxy resins and imide resins are preferable, and those containing a cellulose-based water-soluble polymer such as hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose, and carboxymethylcellulose are preferable in consideration of water-based ink absorption. Besides, polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl acetal, polyurethane, polyester and the like, albumin,
Gelatin, casein, starch, cationized starch,
Natural resins such as gum arabic and sodium alginate can be mentioned.

Above all, considering not only the heat resistance and the ink absorbency but also the transparency and bleeding of the colored portion and the light resistance of the dye, a mixture of hydroxypropylcellulose and methylolated melamine, or a water-soluble acrylic A polymer composed of a monomer is preferred, and a composition containing at least a monomer composed of the following structural units and / or a copolymer with another vinyl monomer is preferred.

[0027]

Embedded image

In the above formula, R ₁ is H or CH ₃ , and R ₂ is H
Or an alkyl group having 1 to 5 carbon atoms.

The curable resin composition may contain various additives, if necessary. Specifically, for example, various surfactants, dye fixatives (waterproofing agents), defoamers, antioxidants, fluorescent brighteners, ultraviolet absorbers, dispersants,
Examples include a viscosity adjuster, a pH adjuster, a fungicide, and a plasticizer. These additives may be arbitrarily selected from conventionally known compounds according to the purpose.

The ink receiving layer 3 can be formed by spin coating, roll coating, bar coating, spray coating, dip coating, or the like. Also, pre-bake is performed as needed.

In the present invention, the ink receiving layer 3 is formed of a photosensitive resin composition whose ink absorptivity is increased or decreased by light irradiation, and a colored portion having a high ink absorptivity by pattern exposure is provided. After forming a non-colored portion having a low (or no) color, the portion to be colored is preferably colored. In this embodiment, when the ink 4 is applied to the colored portion, the non-colored portion interposed between the adjacent colored portions repels the ink, thereby preventing color mixing.

Step (c) The ink receiving layer 3 is coated with R,
The ink 4 containing one of the coloring agents G and B is applied and colored. As the ink used in the present invention, any of dyes and pigments can be used as a colorant, and both liquid inks and solid inks can be used. Is very suitable for

The proportion of the dye or pigment contained in the ink is 0.1 to 15% by weight, preferably 1 to 10% by weight, more preferably 2 to 8% by weight.

As a solvent for the ink, it is preferable to use a mixture of water and an aqueous organic solvent having the following characteristics. That is, a solvent having a boiling point of 150 to 250 ° C. is preferably 5 to 50% by weight, more preferably a boiling point of 180 to 230.
The solvent at 5 ° C. is 5 to 50% by weight, and the solvent having a boiling point of 250 ° C. or more is preferably used at 30% by weight or less, more preferably the solvent having a boiling point of 230 ° C. or more is used at 20% by weight or less.

Specific examples of the above-mentioned aqueous organic solvents are shown in Tables 1 to 3.
Shown in

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

The ink may contain a nonionic, anionic or cationic surfactant or a pH adjuster or a fungicide, if necessary.

As the ink jet system, a bubble jet type using an electrothermal converter or a piezo jet type using a piezoelectric element can be used as an energy generating element, and the coloring area and the coloring pattern can be set arbitrarily. can do.

Here, a preferred method of applying ink by an ink jet method will be described with reference to FIG.
FIG. 2 is a block diagram showing a configuration of an apparatus for applying (drawing) ink onto the ink receiving layer by an ink jet method. In FIG. 2, 21 is a CPU, 22 is a head drive circuit, 23 is an inkjet head, 24 is a program memory, 25 is a transparent substrate, and 26 is an ink droplet.

In the apparatus shown in FIG. 2, an ink jet head 23 is connected to the CPU 21 via a head drive circuit 22. Further, control program information in the program memory 24 is input to the CPU 21. CPU2
1 moves the inkjet head 23 to a predetermined position (not shown), brings a desired pixel position on the transparent substrate 25 below the inkjet head 23, and ejects an ink droplet 26 of a desired color to that position. The ink receiving layer (not shown) on the transparent substrate 25 is colored. By performing this operation for all pixel positions on the transparent substrate 25,
The ink receiving layer is colored in a desired coloring pattern.

Step (d) After the ink 4 has sufficiently penetrated the ink receiving layer 3, the ink receiving layer 3 is cured by heat treatment, and subsequently, the colorant is fixed to obtain the colored portion 5. The heat treatment in the step of fixing the colorant can also serve as the step of curing the ink receiving layer 3.

In the present invention, the fixing of the coloring agent in the colored ink receiving layer 3 is performed by using both heat treatment and chemical treatment. That is, first, at least 200 ° C., preferably 200 ° C.
The heat treatment is performed in an atmosphere at a temperature of from 250C to 250C for 20 to 60 minutes. An oven or a hot plate can be used for the heat treatment.

The chemical treatment in the present invention is achieved by immersing the colored ink receiving layer in a dilute solution of a fixing agent. Examples of the immobilizing agent used here include tannic acid, tartar, polyhydric phenol-based resin, melamine-based resin, and aromatic sulfonic acid condensate. These may be used alone or in combination of two or more.

As a solvent used for the dilute solution of the immobilizing agent, water is preferably used, but other organic solvents are used as long as they dissolve the immobilizing agent and do not interfere with the fixation of the coloring agent. A solvent can be used or used in combination with water. The concentration of the dilute solution is not particularly limited, but is preferably 0.01%.
To 5% by weight, more preferably 0.1 to 2% by weight. The temperature at which the ink receiving layer is immersed in the dilute solution is not particularly limited, but is preferably 0 to 100 ° C, more preferably 25 to 8 ° C.
The temperature is appropriately selected from the range of 0 ° C, preferably 40 to 70 ° C. The immersion time is not particularly limited, but is preferably selected as appropriate from a range of 1 second to 60 minutes, more preferably 10 seconds to 10 minutes, and desirably 30 seconds to 5 minutes. Thereafter, the colorant is completely fixed by performing a heat treatment at 120 to 250 ° C. for 5 to 30 minutes using a hot plate or the like.

Step (e) If necessary, the protective layer 6 is formed to obtain the color filter of the present invention. As the protective layer 6, a photo-curable and / or thermo-curable resin layer, or an inorganic film formed by vapor deposition or sputtering can be used, and has transparency as a color filter, and an ITO film thereafter. Any material that can withstand a liquid crystal element manufacturing process such as a forming process or an alignment film forming process can be used.

Next, an example of the liquid crystal element of the present invention is shown in FIG. FIG. 3 is a schematic cross-sectional view of an example of a liquid crystal element formed using the color filter of the present invention obtained in the step shown in FIG. In the figure, 31 is a counter substrate, 32 is a common electrode, 3
3 is a pixel electrode, 34 and 35 are alignment films, and 36 is a liquid crystal. The present liquid crystal element is an example of an active matrix type (so-called TFT type) liquid crystal element in which a TFT (thin film transistor) is arranged for each pixel.

In general, a liquid crystal element for a color display is formed by combining a color filter side substrate 1 and a counter substrate 31 to form a liquid crystal 3.
6 is formed. Inside the opposing substrate 31, a TFT (not shown) and a transparent pixel electrode 33 are formed in a matrix. A colored portion 5 of a color filter is provided inside the transparent substrate 1 at a position facing the pixel electrode 33 so that R, G, and B are arranged, and a transparent common electrode 32 is provided on the colored portion 5. It is formed. The black matrix 2 is usually formed on the color filter side, but is formed on the counter substrate 31 side in a BM-on-array type liquid crystal element. Further, alignment films 34 and 35 are formed in the planes of both substrates, and by subjecting them to rubbing treatment, liquid crystal molecules can be arranged in a certain direction. These substrates are opposed to each other via a spacer (not shown) or the like, are adhered to each other by a sealing material (not shown), and a gap is filled with a liquid crystal 36.

In the case of the above-mentioned liquid crystal element, a polarizing plate is provided outside both substrates in the case of a transmissive type, and a backlight in which a fluorescent lamp and a scattering plate are combined is generally used. The display is performed by disposing a polarizing plate on the outside of the device and making the liquid crystal 36 function as an optical shutter for changing the light transmittance.

In the above embodiment, the TFT type liquid crystal element has been described, but the present invention is preferably applied to other driving type liquid crystal elements such as a simple matrix type.

Further, in the liquid crystal element of the present invention, as long as it is constituted by using the color filter of the present invention, the other members can use the conventional liquid crystal element technology, and the liquid crystal is generally used. Any of the used TN type liquid crystal and ferroelectric liquid crystal can be used.

[0053]

EXAMPLE On a glass substrate provided with a black matrix having openings of 60 μm × 150 μm, N-methylolacrylamide and hydroxyethyl methacrylate (1: 1 (molar ratio)) were used as an ink receiving layer. The combined curable resin composition was spin-coated so as to have a film thickness of 1.2 μm, and prebaked at 120 ° C. for 20 minutes. Next, each ink of R, G, and B having the following formulation was applied to the ink receiving layer using an ink jet recording apparatus, and colored into a matrix pattern of R, G, and B.

The colored ink receiving layer was subjected to a fixing treatment under the conditions shown in Table 4 to produce a color filter.

[Ink formulation] Dye 5.7% by weight R dye: C.I. I. Acid Red 158 B dye: C.I. I. Acid Blue 83 G dye: C.I. I. Acid Green 9 Ethylene glycol monobutyl ether (boiling point: 170 ° C.) 39.0% by weight Ethyl alcohol (boiling point: 78 ° C.) 6.0% by weight Water 49.3% by weight The G ink is yellow if necessary at the time of ink preparation. Toning was performed with a dye (GI Direct Yellow 86).

[Evaluation Method] Evaluation 1: Color Unevenness in Pixel A liquid crystal element was manufactured using each color filter, and the color unevenness of the pattern portion was visually evaluated by being divided into three groups.

A: No color unevenness B: Some color unevenness is observed C: Color unevenness is observed in more than half of the pattern

Evaluation 2: Loss of color due to elution of dye The magnitude of the discoloration of the pattern portion before and after the colorant immobilization treatment (heat treatment, chemical treatment) was calculated as ΔE determined by the CIE, and the following criteria were used. evaluated.

A: ΔE is 5 or less B: ΔE is more than 5 and 20 or less C: ΔE is more than 20

Evaluation 3: Thermal Discoloration of Pixel The magnitude of the discoloration of the pattern portion measured before and after the heat treatment for fixing the colorant was calculated as ΔE determined by CIE, and evaluated according to the following criteria.

A: ΔE is 5 or less B: ΔE is more than 5 and 20 or less C: ΔE is more than 20

The results of the above evaluation are shown in Table 4.

[0063]

[Table 4]

[0064]

As described above, according to the present invention,
High quality and high reliability color filters without colorant elution or color unevenness can be manufactured in a simple process with good yield, resulting in significant cost reductions and liquid crystal elements with better color display characteristics. Can be provided at a lower cost.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of an apparatus for applying (drawing) ink to an ink receiving layer by an ink jet method in a method for manufacturing a color filter of the present invention.

FIG. 3 is a schematic cross-sectional view of one embodiment of the liquid crystal element of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Black matrix 3 Ink receiving layer 4 Ink 5 Coloring part 6 Protective layer 21 CPU 22 Head drive circuit 23 Ink jet head 24 Program memory 25 Transparent substrate 26 Ink droplet 31 Counter substrate 32 Common electrode 33 Pixel electrode 34, 35 Orientation Film 36 liquid crystal

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akio Kashiwazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Koichiro Nakazawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Masafumi Hirose 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Mayumi Yokoyama 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. F Terms (reference) 2C056 EA24 FB01 FC06 HA44 HA46 2H048 BA64 BB02 BB14 BB44 2H091 FA02Y FA35Y FB03 FC22 FD04 LA12

Claims (5)

[Claims] 1. A method for producing a color filter having a colored portion on a transparent substrate, comprising the steps of: forming an ink receiving layer made of a curable resin composition on the transparent substrate; Applying an ink containing a colorant and coloring the ink receiving layer;
Fixing the coloring agent permeated into the ink receiving layer by performing a chemical treatment after heat treatment in an atmosphere of 00 ° C. or more, thereby producing a color filter. 2. The method for producing a color filter according to claim 1, wherein the curable resin composition contains a resin containing at least a water-soluble acrylic monomer as a monomer component. 3. The method for producing a color filter according to claim 1, wherein the temperature of the heat treatment is 200 to 250 ° C. 4. A colored substrate having a colored portion on a transparent substrate.
3. A color filter manufactured by the method for manufacturing a color filter according to any one of 3. 5. A liquid crystal device comprising a pair of substrates sandwiching liquid crystal, and one substrate comprising the color filter according to claim 4.