JP2002318380A - Ink for color filter substrate and method for manufacturing color filter substrate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter substrate without uneven film thickness and chrominance non-uniformity inside a pixel and being excellent in display quality. SOLUTION: Ink for the color filter substrate is the ink 5 used for manufacturing the color filter substrate 6 of which the coloring pixel is formed by imparting the ink on the substrate with an inkjet method and is characterized by making the ink 5 contain at least a colorant, a binder component, water and an organic solvent with <=40 dyne/cm surface tension, <=0.1 mmHg vapor pressure (20 deg.C) and <=260 deg.C boiling point. The method for manufacturing the color filter uses the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink used for manufacturing a color filter substrate for liquid crystal display, in particular, a color filter substrate for forming colored pixels by an ink jet method, a color filter substrate using the ink, a method for manufacturing the same, and a method for manufacturing the same. The present invention relates to a liquid crystal display device having the color filter substrate.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device is mounted on a personal computer, a word processor, a pachinko game console, an automobile navigation system, a small television, and the like, and the demand has been increasing in recent years. However, the cost of the liquid crystal display device is high, and the demand for cost reduction of the liquid crystal display device is increasing year by year.

A color filter substrate used in a liquid crystal display device is configured by arranging red (R), green (G), and blue (B) colored pixels on a transparent substrate. A black matrix (BM) that blocks light is provided around the periphery to increase the display contrast of the liquid crystal display device. As for the BM, there is a resin BM using a black resin in recent years from a resin BM using a Cr metal thin film.

On the colored pixels, an overcoat layer (protective layer) made of an acrylic resin or an epoxy resin and having a thickness of 0.5 to 2 μm for improving the smoothness of the colored pixels.
Is formed, and a transparent electrode (ITO) film is further formed thereon. As a method for coloring pixels of a color filter substrate, various methods are conventionally known, and these include a dyeing method, a pigment dispersion method, an electrodeposition method, and a printing method.

[0005] The dyeing method is to provide a mordant layer made of a hydrophilic polymer such as gelatin, casein, glue, or polyvinyl alcohol on a glass substrate, and then dye the mordant layer with a dye. Then, a color pixel of R, G, B is formed to obtain a color filter substrate.

The pigment dispersion method is a process of forming a layer by applying a dispersion of a pigment as a coloring material in a photosensitive resin on a transparent substrate by using a spin coater or the like and forming a layer and patterning the layer. -Once for each color of B, a total of 3
This is a method of obtaining a color filter substrate having R, G, and B colored pixels by repeating the process a number of times.

The electrodeposition method comprises the steps of patterning a transparent electrode on a transparent substrate, immersing this in an electrodeposition coating solution such as an electrolytic solution containing a pigment and a resin, and performing electrodeposition coloring. This is a method of obtaining a color filter substrate having R, G, and B colored pixels by repeating each color of B. The printing method is a method of obtaining a color filter substrate of each of R, G, and B by repeating the process of coloring a substrate by offset printing a thermosetting resin in which a pigment-based color material is dispersed.

A common feature of the above-described method for manufacturing a color filter substrate is that the same process must be repeated in order to color R, G, and B colors, which is costly. In addition, there is a problem that the product yield is reduced by increasing the number of steps.

When a color filter substrate is formed by a pigment dispersion method, an expensive photosensitive colored resin is applied onto the substrate by spin coating to form a colored resin layer. The utilization efficiency is very poor, and this is disadvantageous in terms of production cost.

On the other hand, in order to meet the demand for a low-cost color filter substrate with a simpler process, a higher use efficiency of the colored resin and a lower cost of the color filter substrate, a color filter substrate formed with colored pixels using an ink jet method is a special feature. Kaisho 59-7
No. 5205, JP-A-63-235901, JP-A-1-217320 and the like.

The ink-jet method is a method in which an ink containing R, G, and B color materials is jetted onto a transparent substrate by using the ink-jet method, colored, dried and fixed to form colored pixels. According to this method, the required three colors of R, G, and B can be simultaneously formed on the color filter substrate, so that the manufacturing process can be simplified and the cost can be reduced. Further, compared to the dyeing method, the pigment dispersion method, the electrodeposition method, the printing method and the like, the number of steps is small, so that the product yield can be improved.

[0012]

In the conventional photolithography method for producing a color filter substrate, first, a colored photosensitive resin is uniformly applied to the entire surface of the substrate, and then the colored pixels are formed by photolithography. The cross section has a uniform film thickness and is flat, whereas when a colored pixel is formed by the inkjet method, during the drying process of the ink, due to the influence of the surface tension and vapor pressure of the liquid medium of the ink, There is a problem that the cross-sectional shape of the colored pixel becomes convex or concave, and unevenness in film thickness or color is generated in the colored pixel.

As means for solving the above problems, for example,
JP-A-5-21001 discloses a method of forming colored pixels by a printing method and then flattening the colored pixels using a press. However, in this method, the number of steps must be increased in order to include a pressing step, and cost disadvantages can be considered. In addition, the possibility of defects occurring by pressing the substrate increases.
Product yield may be reduced. Also, Japanese Patent Application Laid-Open No. 5-188
Japanese Patent Publication No. 214 discloses a method of ensuring flatness by repeatedly performing printing steps, but this method increases the number of steps and does not provide any advantage.

Accordingly, a first object of the present invention is to provide an ink that can flatten a colored pixel by manipulating the physical properties of the ink in order to prevent irregularities in the colored pixel without increasing the number of steps in the ink jet method. And to provide a color filter substrate excellent in display quality without unevenness in film thickness or color in a colored pixel.

[0015]

The above object is achieved by the present invention described below. That is, the present invention is an ink used for manufacturing a color filter substrate that forms colored pixels by applying ink on a substrate by an inkjet method, wherein the ink is a colorant, a binder component, water, and a surface. A tension of 40 dyne / cm or less, a vapor pressure of 0.1 mmHg or less (20 ° C.), and a boiling point of 260
Provided is an ink for a color filter substrate, characterized by containing at least an organic solvent having a temperature of not more than ° C. Further, the present invention provides a color filter substrate using the ink, a method for manufacturing the same, and a liquid crystal element having a liquid crystal sandwiched between a pair of substrates, wherein one substrate is the above color filter substrate. A liquid crystal element characterized by the following is provided.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. In the present invention, when producing a color filter substrate by an inkjet method, the curable ink used as a material for forming a colored pixel is a liquid ink containing a binder component that is cured by light irradiation or heat treatment or a combination thereof, and Contains at least a dye or a water-dispersible pigment, a water-soluble organic solvent, and water.

When the water-soluble organic solvent in the ink has a surface tension of 40 dyne / cm or less and a vapor pressure of 0.1 mmH
g (20 ° C.) or less and containing at least an organic solvent having a boiling point of 260 ° C. or less, because the surface tension of the water-soluble organic solvent is low, the ink spreads well within the colored pixels, and At the stage when the ink is applied by the ink jet method, a certain degree of flatness is secured.

Further, since the vapor pressure of the water-soluble organic solvent is low, the drying is performed slowly in the drying process of the ink, and the colored pixels are hardened while maintaining the flatness of the colored pixels. Further, by using a solvent having a boiling point of 260 ° C. or less,
When the colored pixels are cured by heating, all the solvent in the ink can be removed, and the solid content in the ink is directly reflected on the film thickness, so that more excellent flatness can be secured.

In order to obtain the above-mentioned effects of the present invention, there is an optimum ratio of the water-soluble organic solvent to the ink. In the present invention, it is preferable that the water-soluble organic solvent is contained in the ink in an amount of 10% by weight or more and 40% by weight or less.

FIG. 1 is a schematic sectional view showing the steps of one embodiment of a method for manufacturing a color filter substrate according to the present invention. In the figure, 1 is a transparent substrate, 2 is a black pigment-containing resist,
3 is a partition, 4 is an inkjet head, 5 is ink, 6
Denotes a color filter substrate, and 7 denotes a protective film.

As the transparent substrate 1, a glass substrate is generally used, but other materials can be used as long as they satisfy required characteristics such as transparency and mechanical strength as a color filter substrate. Examples include a transparent resin plate, a resin film, a CRT display surface, a light-receiving surface of an image pickup tube, CC
Examples include a wafer on which a solid-state imaging device such as D, BBD, CID, and BASIS is formed, a contact image sensor using a thin film semiconductor, a liquid crystal display surface, and a photoconductor surface for color electrophotography.

In the process of forming a resin black matrix in the method for manufacturing a color filter substrate of the present invention, first, as shown in FIG. 1, a black pigment-containing resist 2 which is a light-shielding material is spin-coated on a transparent substrate 1. It is applied uniformly by a roll coating method, a printing method or the like, and dried. As the light-shielding material used at this time, a material having at least a photosensitive resin and a black colorant is used. As the colorant, a pigment such as carbon black or iron black is preferably used.

Examples of the photosensitive resin include, for example, polymethyl methacrylate, polystyrene sulfone, polyhexafluorobutyl methacrylate, cholic acid, o-nitrobenzyl esters, etc., which are cured by irradiation with ultraviolet rays, electron beams or the like. . In the present invention, it is preferable to use, as the photosensitive resin, a negative photosensitive resin in which the irradiated portion is photocured, particularly by light irradiation.

The curable ink used in the present invention is a liquid ink containing a binder component which is cured by light irradiation, heat treatment, or a combination thereof. In the present invention, the ink is applied to a pixel area by an ink jet recording method. Since it is preferable to form a colored pixel by applying the ink, the ink further contains at least a coloring material, a water-soluble organic solvent, and water.

As the coloring material, a material which can obtain desired spectral characteristics among pigments, dyes and the like can be appropriately selected and used alone or in combination. As the binder, a water-soluble or water-dispersible thermosetting resin, for example, an acrylic resin, an epoxy resin, a urethane resin, a polyamide resin, a polyester resin, or the like is used. The concentration of the colorant in the ink is 0.1 to 15% by weight of the ink.
%, Particularly 1 to 10%, and the concentration of the curable resin is preferably 0.1 to 15% by weight of the ink, more preferably 1 to 10%.

Various solvents can be used as the water-soluble organic solvent, and a mixed solvent of water and a water-soluble organic solvent is preferably used from the viewpoint of dischargeability in an ink jet system. Examples of the solvent that can be used include alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; Amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol and butylene Glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol,
Alkylene glycols having an alkylene group containing 2 to 6 carbon atoms, such as diethylene glycol; glycerin; ethylene glycol monomethyl (or ethyl) ether;
Diethylene glycol methyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether;
-Methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-
Dimethyl-2-imidazolidinone and the like.

Of these, glycol solvents and glycerin are preferably used. In the present invention,
Further, at least one of the water-soluble organic solvents used for the ink material has a surface tension of 40 dyne / cm or less, a vapor pressure of 0.1 mmHg (20 ° C.) or less, and a boiling point of 260 ° C.
It must be an organic solvent that is: Further, the water-soluble organic solvent accounts for at least 10% by weight of the total weight of the ink.
It is desirably 0% by weight or less.

In the present invention, as an ink jet recording system preferably used for coloring a pixel area, which is preferably used when forming a colored pixel, for example, a bubble jet (registered trademark) using an electrothermal converter as an energy generating element is used. And a piezo jet type using a piezoelectric element. The thickness of the colored pixel thus formed is about 0.5 to 5 μm, preferably 0.5 to 1.5 μm.
μm, and the variation width of the thickness is ± 30% or less, preferably 20% or less, more preferably 15% or less.

The color filter substrate of the present invention formed as described above effectively protects the color filter substrate from the case where the color filter substrate requires more excellent flatness and various extreme environmental conditions. Therefore, it is preferable to form a protective film on the color filter substrate.

As the protective film, a resin material curable by light irradiation or heat treatment, or a combination thereof, or an inorganic film formed by vapor deposition or sputtering can be used. In the subsequent process, for example, when forming a liquid crystal element, any process that can withstand the ITO film forming process and the alignment film forming process can be used. For example, acrylic,
Polyamide, polyimide, polyurethane, polycarbonate, silicon-based resin, SiN ₄ , SiO ₂ , S
Inorganic compounds such as iO, Al ₂ O ₃ and Ta ₂ O ₅ can be mentioned.

Examples of a method for providing the protective film include a coating method such as spin coating, roll coating, and printing, and a vapor deposition method. The thickness of the protective film is 0.1 μm to 2 μm.
It is preferable that the film thickness be about the same.

[0032]

The present invention will be described more specifically below with reference to examples and comparative examples. Examples of water-soluble organic solvents used in Examples and Comparative Examples are shown in Table 1 below. The following Examples and Comparative Examples are examples using the water-soluble organic solvents described in Table 1.

Example 1 A curable ink having the following composition was prepared.・ 6% by weight of blue dye ・ 4% by weight of thermosetting resin ・ 20% by weight of ethylene glycol ・ 20% by weight of hexylene glycol ・ 50% by weight of water

After mixing the above components and stirring for 1 hour, the mixture was filtered through a membrane filter to remove insolubles. The surface tension of this solution was 35 dyne / cm. However,
CIAcid Blue 113 was used as a blue dye.

A glass substrate (manufactured by Corning Incorporated) is washed by a conventional method, and a black resist (trade name: CK-S171X,
A black matrix was formed on a glass substrate by photolithography using Fujifilm Ohlin Co., Ltd.). The thickness of this black matrix was 2 μm. An ink jet recording apparatus is used for the opening of the black matrix, and the amount of ink applied to one opening is 200 p.
The ink was applied under such a condition as 1.

The ejection of the curable ink from the ink jet recording apparatus was good. After applying the curable ink, the ink was cured by a heat treatment at 230 ° C. for 30 minutes. When the shape of the colored pixel after curing was measured using a stylus type surface shape measuring device, the film thickness was 1.2 μm ± 0.18.
It was confirmed that a very flat colored pixel having no irregularities of μm was formed.

No problems such as color mixing and density unevenness were observed in the color filter substrate prepared as described above. Forming a protective film on the color filter substrate;
A series of operations such as formation of an ITO (electrode), formation of an alignment film, and sealing of a liquid crystal material were performed to produce a liquid crystal element for color display. When this liquid crystal element was driven continuously in a temperature range of -20 ° C to 60 ° C for 1000 hours, no display problem occurred.

Example 2 A curable ink having the following composition was prepared. -6% by weight of green dye-3.5% by weight of thermosetting resin-20% by weight of diethylene glycol-20% by weight of 1,2-propanediol-50.5% by weight of water

After mixing the above components and stirring for 1 hour, the mixture was filtered through a membrane filter to remove insolubles. The surface tension of this solution was 50.2 dyne / cm. However, CIAcid green 25 was used as a green dye.

In this embodiment, similar to the first embodiment,
The dischargeability of the curable ink by inkjet was good. Further, as in the case of Example 1, no problems such as color mixing and density unevenness were observed in the color filter substrate of the present example.

Using the above-mentioned color filter substrate, a liquid crystal element was prepared in the same manner as in Example 1, and was driven continuously at a temperature in the range of -20.degree. C. to 60.degree. C. for 1,000 hours. No display problem occurred. . Further, when the shape after curing was measured using a stylus type surface shape measuring device, the film thickness was 1.2 μm.
It was confirmed that a very flat colored pixel having no unevenness of ± 0.18 μm was formed.

Example 3 A curable ink having the following composition was prepared. -Blue dye 6% by weight-Thermosetting resin 4% by weight-Ethylene glycol 15% by weight-Diethylene glycol 15% by weight-Hexylene glycol 10% by weight-Water 50% by weight

After the above components were mixed and stirred for 1 hour, the mixture was filtered with a membrane filter to remove insolubles. The surface tension of this solution was 40 dyne / cm. However,
CIAcid Blue 113 was used as a blue dye.

In this embodiment, similar to the first embodiment,
The dischargeability of the curable ink by inkjet was good. Further, as in the case of Example 1, no problems such as color mixing and density unevenness were observed in the color filter substrate of the present example.

Using the above color filter substrate, a liquid crystal element was produced in the same manner as in Example 1, and the liquid crystal element was driven in a temperature range of -20 ° C. to 60 ° C. for 1000 hours. As a result, no display problem occurred. . Further, when the shape after curing was measured using a stylus type surface shape measuring device, the film thickness was 1.2 μm.
It was confirmed that a very flat colored pixel having no unevenness of ± 0.18 μm was formed.

Example 4 A curable ink having the following composition was prepared.・ 6% by weight of blue dye ・ 4% by weight of thermosetting resin ・ 15% by weight of ethylene glycol ・ 15% by weight of diethylene glycol ・ 10% by weight of dipropylene glycol ・ 50% by weight of water

After mixing the above components and stirring for 1 hour, the mixture was filtered through a membrane filter to remove insolubles. The surface tension of this solution was 48.3 dyne / cm. However, CIAcid Blue 113 was used as a blue dye.

In this embodiment, as in the first embodiment,
The dischargeability of the curable ink by inkjet was good. Further, as in the case of Example 1, no problems such as color mixing and density unevenness were observed in the color filter substrate of the present example.

Using the above-mentioned color filter substrate, a liquid crystal element was produced in the same manner as in Example 1 and was driven continuously for 1000 hours in a temperature range of -20 ° C. to 60 ° C., and no display problem occurred. . Further, when the shape after curing was measured using a stylus type surface shape measuring device, the film thickness was 1.2 μm.
It was confirmed that a very flat colored pixel having no unevenness of ± 0.18 μm was formed.

Comparative Example 1 A curable ink having the following composition was prepared.

After mixing the above components and stirring for 1 hour, the mixture was filtered through a membrane filter to remove insolubles. The surface tension of this solution was 50 dyne / cm. However,
CIAcid blue 113 was used as a blue dye.

In this embodiment, similar to the first embodiment,
The dischargeability of the curable ink by inkjet was good. Further, as in the case of Example 1, no problems such as color mixing and density unevenness were observed in the color filter substrate of the present example.

Using the above color filter substrate, a liquid crystal element was prepared in the same manner as in Example 1, and was driven continuously for 1000 hours in a temperature range of -20 ° C. to 60 ° C., and no display problem occurred. . However, when the shape after curing was measured using a stylus type surface profiler, the film thickness was 1.2 μm.
Irregularities of m ± 0.5 μm were confirmed.

[0054]

As described above, according to the present invention, the color pixels can be flattened by manipulating the physical properties of the ink in order to prevent unevenness in the color pixels without increasing the number of steps in the ink jet method. In addition, it is possible to provide a color filter substrate which is excellent in display quality without unevenness in film thickness or color in a colored pixel.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing steps of a method for manufacturing a color filter substrate.

[Explanation of symbols]

 1: Transparent substrate 2: Black pigment-containing resist 3: Partition wall 4: Inkjet head 5: Ink 6: Color filter substrate 7: Protective film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA06 FB01 FC02 2H048 BA11 BA47 BA64 BB02 BB42 2H091 FA02Y FA35Y FB02 FB12 FC01 FC02 FC10 GA01 GA03 GA13 GA16 LA12 LA18 4J039 AD09 AD10 AE04 AE05 AE06 AE08 BC07 BC09 BC09 BC09 BC09 BC09 BC50 BC51 BE01 BE02 BE12 CA03 CA06 EA03 EA05 FA04 GA24

Claims (8)

[Claims] 1. An ink used for manufacturing a color filter substrate for forming a colored pixel by applying ink on a substrate by an ink jet method, wherein the ink comprises a colorant, a binder component, water, and a surface tension. 40
A color filter substrate ink comprising at least an organic solvent having a dyne / cm or less, a vapor pressure of 0.1 mmHg or less (20 ° C.), and a boiling point of 260 ° C. or less. 2. The method according to claim 1, wherein the organic solvent contains 10% by weight of the ink.
The ink for a color filter substrate according to claim 1, which is contained as described above. 3. The ink for a color filter substrate according to claim 1, wherein the organic solvent is a glycol-based organic solvent. 4. The ink for a color filter substrate according to claim 1, wherein the organic solvent is a mixture of a plurality of glycol-based organic solvents. 5. A method for producing a color filter substrate for forming colored pixels by applying ink on a substrate by an ink jet method, wherein the ink is the ink according to claim 1. A method for manufacturing a color filter substrate, comprising: 6. The method for manufacturing a color filter substrate according to claim 5, wherein the substrate is an active matrix substrate having a TFT array, and a partition of the substrate is a black matrix formed by patterning a black resist. 7. A color filter substrate manufactured by the manufacturing method according to claim 5. Description: 8. A liquid crystal element having a liquid crystal sandwiched between a pair of substrates, wherein one of the substrates is the color filter substrate according to claim 7.