JPH02161402A - Color filter - Google Patents

Abstract

PURPOSE:To directly form transparent picture element electrodes on filters without protective layers with a low cost printing method by printing and forming a thermosetting resin of a solvent solubilization type and coloring agents contg. dyestuffs, dispersion assistants and coupling agents by a prescribed number of colors in desired pattern shapes on a substrate. CONSTITUTION:The colored layers contg. either of the thermosetting melamine resin of the solvent solubilization type alone which does not lose transparency in a 200 to 300 deg.C hot atmosphere and has >=200 deg.C peak temp. of the heat generated by curing or a mixture composed of the melamine resin and an epoxy resin, dyestuffs, dispersion assistants and coupling agents are printed and formed by the prescribed number in desired pattern shapes on the substrate. Org. pigments having excellent light resistance and heat resistance and good dispersibility in the resin are preferably used as the dyestuffs in this case. Coupling agents which have an org. functional group having affinity to the melamine resin and the epoxy resin and a hydrolysis group having affinity to inorg. materials in one molecule and have no coloration are preferable as the coupling agents. The color filters are formed by the low cost printing method in this way without having a need for the protective layer to provide a transparent conductive layer of low resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a color filter suitable for being installed in a liquid crystal cell of a color liquid crystal display device. Specifically, the present invention relates to a color filter in which a colored film is formed on a substrate such as glass by an intaglio or intaglio offset printing method.

<Prior art> Full-color display devices using liquid crystals have already been put into practical use, and are characterized by being thin and lightweight, low-voltage drive, and low power consumption, and large displays with several panels arranged have also been put into practical use. ing. These devices basically have red, green, and
This method reproduces full color by driving the liquid crystal as an optical filter corresponding to the patterned filter layer of three colors of blue.

Many methods have been proposed for patterning the filter layer, but they can be broadly divided into those using photolithography and those using printing.

The former is a method in which a color pattern is formed by dyeing, discharge printing, vapor deposition, or etching using a resist film patterned by a well-known method, while the latter is a method in which a color pattern is literally formed directly by printing. . Photolithography has the advantage of higher dimensional accuracy (and the ability to form fine patterns) than printing;
Each process of etching and peeling off the resist film must be repeated. On the other hand, the printing method can create a pattern by simply repeating printing and drying, so it is low cost and excellent in mass production.

Furthermore, advances in printing technology have made it possible to print fine patterns with high dimensional accuracy and smoothness, and there is an urgent need to develop durable color filters.

<Problems to be solved by the invention> When a color filter is provided in a liquid crystal cell in a full-color display using a liquid crystal, it has excellent heat resistance, light resistance, chemical resistance, transparency, and adhesion to a substrate. requires specific characteristics. That is, in the liquid crystal cell manufacturing process, chemical resistance is required from the cleaning step, and heat resistance is required from the alignment film forming step, the transparent conductive film forming step, and the like. In particular, regarding the formation of transparent conductive films, when thin film elements such as matrix-type Y4 film transistors and nonlinear elements are used as circuits that control each liquid crystal cell independently, full color can be achieved by providing a common electrode on the color filter. Display is possible, and when forming a transparent conductive film, it is possible to form the film at room temperature. However, the cost of liquid crystal cells made using this method is very high, and the yield rate of the cells is also good.On the other hand, there is a method that does not use drive elements, called the X-Y simple matrix method, in which two substrates sandwiching the liquid crystal are used. That is, a pixel electrode is formed by X and Y on the signal side electrode substrate and the scanning side electrode substrate, respectively, for display. The former method can be fully supported by a dyeing method using gelatin by providing a protective layer.In contrast to the latter method, providing a transparent pixel electrode on top of the color filter layer is similar to the conventional dye-dyed filter layer. Organic filters used as materials have insufficient heat resistance and wrinkles, cracks, etc. occur. On the other hand, melamine resin has excellent heat resistance but poor adhesion to glass substrates, and epoxy resin has excellent adhesion but poor heat resistance.

<Purpose of the Invention> The present invention has been realized through various studies in terms of the above-mentioned heat resistance and adhesion to glass substrates, and it is possible to form a color filter using a low-cost printing method, and it is possible to form a color filter using a transparent pixel tF. )
i provides a color filter that can be formed directly on the filter without a protective layer.

<Means for Solving the Problems> In other words, the present invention provides a method for producing a film on a substrate that has a curing exothermic peak temperature of 200°C without losing transparency in a hot atmosphere of 200 to 300″C.
Printing a colored layer containing either a solvent-soluble thermosetting melamine resin alone or a mixture of a melamine resin and an epoxy resin, a dye, a dispersion aid, and a coupling agent, in a predetermined number of colors and in a desired pattern. It is a color filter characterized by being formed by forming.

In the color filter of the present invention, the colored layer is formed by an intaglio or intaglio offset printing method, and it is preferable to use an organic pigment that has excellent light resistance and heat resistance and has good dispersibility in a resin as a pigment. As the coupling agent, it is preferable to use a non-colored coupling agent having in one molecule an organic functional organ that has an affinity for melamine resins and epoxy resins and a hydrolyzable group that has an affinity for inorganic materials.

<Detailed Description of the Invention> Fig. 1 shows an example of a color liquid crystal display device using a color filter.
1) passes through the polarizing plate (2), the transparent substrate (3), the transparent pixel electrode (4), the alignment film (5), the liquid crystal (6), the alignment film (7), the transparent pixel electrode (8), and the colored layer (9). and is separated into the three primary colors.

In response to the electrical signals applied to the pixel electrodes (4) and (8), the liquid crystal (6) is aligned and operates as an optical shutter by the action of the polarizing plate θ1), and the electrical signals are converted into information as three primary colors. Ru. At this time, since gelatin dyed with dye was used as the colored layer (9), the heat resistance of the colored film was poor, so the transparent pixel electrode (8) was used as the colored layer (9).
) had to be formed under the As a result, since the colored layer (9) is interposed between the liquid crystal (6) and the transparent pixel electrode (8), the response time of the liquid crystal to voltage ON/OFF becomes slow, and the viewing angle of the liquid crystal panel becomes narrow. Color shift due to parallax was also likely to occur.

Therefore, the performance of the color liquid crystal display device is poor. In the present invention, even if transparent pixel electrodes are formed directly on the colored layer (9), the color filter will not have cracks, wrinkles, etc.
0 with heat resistance and film strength that does not cause color turbidity etc.
As a result of detailed comparative studies of various binder resins,
Examples of thermosetting resins include epoxy resins, melamine resins, phenol resins, and polyester resins, each of which has advantages and disadvantages. The characteristics when each resin is used alone are described below. When using epoxy resin alone, 1 yen of colored layer weighs 0.5μ to 3μ! In the case of a film, even if an acid anhydride (hexahydrophthalic anhydride, tetrahydrophthalic anhydride) is added to the curing agent, the curing agent will sublime due to the thin film, making it impossible to obtain sufficient crosslinking density. In addition, when an amine curing agent is used, the pot life of the ink is short (and the cured product is colored, which affects the transmittance. When melamine resin is used alone, the amino group has a complex three-dimensional network structure with hexafunctionality. Because it is a polymer with a high heat resistance, it has relatively high heat resistance.While most thermoplastic resins melt at 100 to 150'C, melamine resins have a high temperature of 200 to 300'C, but do not adhere tightly to glass substrates. I have a bad weakness.

Therefore, by mixing the two, it was possible to form a colored layer that had adhesion to the glass substrate with the epoxy resin and heat resistance and film strength with the melamine resin, and it became possible to form a transparent conductive pixel electrode directly on it.

Furthermore, it was shown that the adhesion was improved by internally adding a coupling agent, and even when a melamine resin alone was used, the adhesion was improved by internally adding a coupling agent. Sufficient adhesion can be obtained. The internal amount of coupling agent is preferably from 0.5% to 20% by weight based on the weight of the ink. If it is less than 0.5 weight percent, the effect of adhesion will vary, and if it is more than 2.0 weight percent, it tends to cause thickening and gelation of the ink.

Representative examples of coupling agents that can be used in the present invention are shown below.

■T-glycidoxypropyltrimethoxysilane (manufactured by Toshiba Silicone ■) ■T-aminopropyltriethoxysilane (manufactured by Toshiba Silicone ■) ■N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (manufactured by Toshiba Silicone ■) The crosslinking reaction when blending melamine resin and epoxy resin is a ring-opening reaction between the epoxy ring and the amino group. However, when dispersing pigments, if a blend of melamine resin and epoxy resin is used as a binder resin, a crosslinking reaction will partially occur during dispersion, significantly impairing the storage stability of the ink and causing it to gel in a very short time. . Therefore, when dispersing the pigment, the melamine resin and the epoxy resin are separately formed into inks, and then the two types of ink are mixed in a desired ratio. Further, the coupling agent is added at the final stage after forming the ink for reasons such as preventing gelation. There is no problem with the two resins that can be used in the present invention as long as they are less colored and soluble in a solvent having an alcoholic hydroxyl group, but in terms of solubility in melamine, the epoxy equivalent of the epoxy resin is preferably less than too.

Further, the required characteristics can be satisfied by mixing the melamine resin and the epoxy resin in a blending ratio of 300% or less of the epoxy resin to the melamine resin. Conversely, as the blending ratio of the epoxy resin increases beyond 30% by weight, the heat resistance deteriorates.

Representative examples of epoxy resins and melamine resins that can be used in the present invention are shown below by trade names.

■Bisphenol type epoxy resin Epicoat 815.819, 827.828, 8
32.834.1001.1O04,1007 (Made by Yuka Shell Epoxy ■) ■Melamine resin knee panties 20SE-60, 20H3, 120 Cymel 350.327 (Made by Mitsui Toatsu Chemical ■) ■Benzoguanamine resin (1 liter of melamine resin) Pigments that can be used in the present invention, such as Cymil 1123.1125 (manufactured by Mitsui Toatsu Chemical Co., Ltd.), are required to have heat resistance, chemical resistance, solvent resistance, liquid crystal resistance, and light resistance, just like the binder resin. Furthermore, appropriate spectrum and transparency are required, so the pigment must have a large absorption coefficient for visible light, and the average primary particle size must be sufficiently small for visible light. is desirable,
The primary particle size of the pigment is desired to be 0.3μ or less, preferably 0.1μ or less from the viewpoint of transparency, so the primary particle size of the pigment is reduced by a known method such as a sand mill, kneader, or two rolls. It is also effective to improve transparency and absorption coefficient.

Materials excellent in various resistances as pigments that can be used in the present invention are shown below using color index (C, 1,) numbers.

C, 1, yellow pigment 24.86.93.94,108
,109.110°117.125,137.138.
147,153.154,166,168 C,! , orange pigment 36.43.51.55.59
．． 61C9I, red pigment 97,122,123,1
49.168.177.178.180.18? , 19
0.192.209゜215.216thu217.2
20.223.224.226.227.228.24
0C,1, Violet pigment 19.23.29.30
．． 37.40, C, 1, blue pigment 15.15:1.
15:3.15:4.15:6.22.60.64 C,l, green pigment 7.36 C,I, brown pigment 23.25.26C,1, black pigment 7 Solvent that can be used in the present invention The solvent dissolves the epoxy resin and melamine resin, and the evaporation rate of the solvent has a great effect on printability. This process includes the steps of transferring the ink applied to the image area of the intaglio from the intaglio to the transfer body, transferring the ink on the transfer body from the intaglio to the transfer body, and transferring the ink on the transfer body to the substrate. Since the pattern is formed by offset printing, the solvent that can be used in the present invention must have at least one alcoholic hydroxyl group and have a boiling point of 120°C in order to improve reproducibility and prevent the shape from deforming due to repetition.
It has been found that a mixed solvent of one or more selected from aliphatic alcohols, preferably polyhydric alcohol derivatives, at a temperature of .degree. C. to 260.degree. C. satisfies the above requirements.

The names of solvents that can be used in the present invention are shown below.

Ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, ethylene glycol monoethyl ether, ethylene glycol monohexyl ether, ethylene glycol monoacetate, methoxymethoxyethanol, diethylene glycol, diethylene glycol 7-methyl ether, diethylene glycol monoethyl Ether, diethylene glycol motubutyl ether, diethylene glycol monoacetate, triethylene glycol monomethyl needle, triethylene glycol monoethyl ether, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol-n-propyl ether, propylene glycol isopropyl Ether, propylene glycol monobutyl ether, propylene glycol monoacetate, ■-butoxyethoxyprobanol, among these solvents, low boiling point solvents are combined with high boiling point solvents, and high boiling point solvents are combined with low boiling point solvents to increase the drying speed. Adjust. Furthermore, since the fluidity properties vary somewhat depending on the solvent composition, the solvent selection is ultimately determined by the printing speed and other composition contents.

In principle, the ink for color filters according to the present invention can be produced by simply kneading the resin, pigment, and solvent described above. However, when using the same resin, the fluidity of the ink differs depending on the pigment, and the pigment content of each color that provides the optimum spectrum also differs, resulting in large differences in the normality of the ink of each color. In this case, addition of a dispersion aid is effective. Dispersing aids improve pigment dispersibility and prevent pigment re-aggregation, so they have the effect of reducing thixotropy, lowering ink viscosity, improving permeation, and improving coating film smoothness. .

Examples of dispersion aids that can be used in the present invention include surfactants such as cationic surfactants, anionic surfactants, and nonionic surfactants, and organic dye derivatives. Preferably, an organic dye derivative is used.
It is a derivative of face dye or dye, such as ab-based,
1 to 4 substituents in phthalocyanine-based, quinacridone-based, anthraquinone-based, perylene-based, perinone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, triphenylmethane-based, and metal complex salt-based organic dye compounds. It is a compound that has A substituent (^ group) is a hydroxyl group, a carboxyl group, a sulfonic acid group, a carbolamide group, etc., or a substituent formed by the following general formula.

-CH, -X-A (x: oxygen or sulfur atom, A: aryl group) (x: alkylene group, RI Rt: hydrogen atom, alkyl group, or a heterocycle containing at least a nitrogen atom in R1 and R8) (R1 : alkyl group or aryl group, R2 : alkyl group or aryl group, or R1 and R8 together are a heterocycle containing at least a nitrogen atom) (R : hydrogen atom, alkyl group, : alkylene group, : alkyl group, alkoxyalkyl group, or cycloalkyl group, R3: alkyl group or cycloalkyl group or Rt
and R1 (heterocycle containing at least a nitrogen atom) Note that the organic pigment and the parent organic pigment of the derivative are usually the same in terms of hue, but they do not necessarily have to match.

As shown in Fig. 2, the structure of the color filter is such that a black light-shielding layer 09 is formed between the colored filter layers 07JO and 041 of each color, and a black pigment such as carbon black or a mixed color pigment of cyan, magenta, and yellow pigments is used. It is preferable to form a pattern with a colored composition set including
The light shielding layer 051 is also a colored filter layer 02) 03) 041
Similarly, heat resistance is required, so it is best to use a pigment dispersed in a heat-resistant resin such as melamine.Production of color filter ink is basically the production of ordinary printing ink. There is little difference in the method
The ink can be fixed by simply heating it at 200° C. to 230° C. for a period of 2 to 31 yen to obtain a practically sufficient mechanical density and adhesion to the substrate. The ink for color filters according to the present invention will be described below.

(Ink example) Imil 350 (manufactured by Mitsui Toatsu Chemicals) is used as a melamine resin.
(trade name) and epoxy resin Epicoat 828 manufactured by Yuka Shell Epoxy, 2 diethylene glycol monoethyl ether and 2 ethylene glycol monobutyl ale.
A varnish made by dissolving 20% of each resin in the solvent mixed with :1'! B crushed.

Next, pigments and, if necessary, dispersion aids, extender pigments and solvents were added to each of the above varnishes, and thoroughly kneaded using three rolls to produce red, green, and blue inks, respectively.

As for the ratio of both resins, 20% of epoxy ink is added to melamine ink to make the final ink, and 1.0% of silane coupling agent (
T-glycidoxypropyltrimethogine silane (manufactured by Toshiba Silicone Q) was added.

For each color, kneading was performed with the following composition. (All ratios are weight %) Aerosil R-972 (Japan Aerosil ■: silicon dioxide fine powder) was used as the extender pigment here. The compositions of the pigments and dispersion aids for each color are shown below.

(For red filter) ■ Pigment Lionogen Red GO (C91 manufactured by Toyo Ink Manufacturing ■)
Mixture of 70 parts of Pigment Red 168) with 30 parts of Onogen Orange R (manufactured by Toyo Ink Mfg. C.1, Pigment Orange 36) ■Dispersion aid Compound of the following structural formula (for green filter) ■Pigment Lionol Green 2YS (C1 manufactured by Toyo Ink Manufacturing Co., Ltd.)
! , Pigment Green 36) 75 parts mixture with 25 parts of Onogen Yellow 3G (Toyo Ink Manufacture C3!, Pigment Yellow 154) Dispersion aid The following low chlorinated copper phthalocyanine derivative C! 4 CuPCA[SOzN(CmHv)ginn=1.
7 (For blue filter) ■Kanne 4 Rio No Blue ES C Toyo Ink Manufacturing @c, 1. Pigment Blue 15:6) 80 parts Mixture with 20 parts of Onogen Violet RL (C, 1 manufactured by Toyo Ink Manufacturing ■, Pigment Violet 23) ■ Dispersion aid The following copper phthalocyanine derivative n = 2.0 (Color Manufacture of Filter) FIG. 3 is a perspective view showing a state in which the ink of the present invention is printed on a substrate by an intaglio offset printing method. Intaglio (2
After applying the ink (191) prepared in Example 1 on the plate depth 10 μm) and scraping off the excess ink 09 with a doctor 08, the ink was applied onto the intaglio surface on the blanket QΦ. The blanket QO was transferred to the glass substrate Qυ, and the ink on the blanket QI was transferred onto the glass substrate Qυ.This operation was repeated for each color line to form a pattern.

As a result, we created a color filter with the following characteristics.

0 Spectral characteristics...shown in Figure 4 (solid line).

(2) Heat resistance: After heat treatment at 230°C for 22 hours, the change in spectral transmittance is within 5% as shown in Figure 4 (-dotted chain line).

■Applicability of attaching a transparent pixel electrode film... Even if a transparent conductive layer of 10Ω/hole to 15Ω/hole is attached on a color filter by high-temperature sputtering without a protective layer, cracks, wrinkles, etc. will not occur. No occurrence.

■Chemical resistance, solvent resistance...Table 1 shows the results of immersion or ultrasonic cleaning.

It was immersed in an ultrasonic bath for 1 minute.

Appearance immediately after pulling up ◎ - No color change, wrinkles, or cracks No cellophane peeling → No peeling <Effects of the invention> The color filter made of the ink for color filters of the present invention has a high heat resistance of the colored layer, so the filter remains intact even after heat treatment. Since the spectral characteristics of the material do not deteriorate and the mechanical strength is improved, a protective layer, which conventionally required a protective layer to provide a low-resistance transparent conductive layer, can now be directly attached. Furthermore, since printing is possible, the process is shorter than that of photolithography, making it possible to supply color filters at low cost.

Furthermore, since it can be formed by a printing method as shown in FIG. 3, large color filters can be easily produced.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an example of a color liquid crystal display device;
FIG. 2 is a sectional view showing one embodiment of the color filter of the present invention, FIG. 3 is an explanatory diagram showing an outline of printing for creating a color filter using the ink of the present invention, and FIG. 4 is a cross-sectional view showing an embodiment of the color filter of the present invention. FIG. 3 is a graph diagram showing the spectral characteristics of a color filter obtained using ink. (1)...Light source 02) Side 04...Colored filter layer +21 (I+1...Polarizing plate 0ω...
Light shielding layer (3) θ0)...Transparent substrate 0ω...Transparent substrate (41(8)...Transparent pixel 7i pole 0ri...plate (5) (7)...Alignment film 0 mark ...Doctor (6)...Liquid crystal Q91...Ink (9)...Color filter Q@...Planke Noan...Transparent substrate patent application Hitotoppan Printing Co., Ltd. Figure 1 Good Chomaru (1

Claims (1)

[Scope of Claims] (1) A solvent-soluble thermosetting resin, a coloring agent containing a pigment, a dispersion aid, and a coupling agent are printed and formed in a desired pattern in a predetermined number of colors on a substrate. A color filter that is characterized by: (2) The color filter according to claim 1, wherein the thermosetting resin is composed of a melamine resin alone or a mixture of an epoxy resin and a melamine resin. (3) The color filter according to claim 1, wherein the coupling agent has an organic functional group having an affinity for an organic material and a hydrolyzable group having an affinity for an inorganic material in one molecule. (4) The color filter according to claim 1, wherein the dye is an organic pigment. (5) The color filter according to claim 1, wherein a transparent conductive film is directly formed on the colored layer. (6) The color filter according to claim 1, wherein the colored layer is printed by an intaglio printing method or an intaglio offset printing method.