JPS6254774A - Ink composition for color filter - Google Patents

Abstract

PURPOSE:To provide the titled compsn. having excellent resistance to heat, light, chemicals and solvents, spectral properties and adhesion to substrates and suitable for use in a color filter for color separation of a color display device, consisting of an epoxy resin, a solvent and a dye. CONSTITUTION:A bisphenol type, novolak type or cycloaliph. epoxy resin (A), a dye (B) composed of a pigment having a primary particle size of 0.3mu or below, at least one solvent (C) selected from among aliph. compds. contg. at least one alcoholic hydroxyl group and having a b.p. of 120-260 deg.C (e.g., ethylene glycol monomethyl ether) and optionally, pigment (e.g., SiO2), dispersion aid (e.g., copper phthalocyanine derivative) are kneaded.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial Field of Application) The present invention relates to an ink composition for forming a highly durable color filter for color separation in a color display device. More specifically, the present invention relates to an ink composition for intaglio printing or intaglio plate offset used in color display devices that combine an electro-optical effect such as a liquid crystal and a color separation filter.

(Prior art) Full-color display devices using liquid crystals have already been put into practical use, and are characterized by m-type light weight, low voltage drive, and low power consumption. 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 shutter in correspondence with 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 literally a method in which a color pattern is directly formed by printing. . Photolithography has the advantage of higher dimensional accuracy and the ability to form fine patterns than printing, but compared to printing, it requires at least the application of a resist film, exposure, and
Each step of etching and resist film peeling 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 inks that can form color filters.

(Problems to be Solved by the Invention) Next, the main characteristics required of a color filter are listed below.

■During the liquid crystal cell manufacturing process, chemical resistance is improved from the cleaning process.
Heat resistance of at least 200°C is required for the alignment film forming process, i3 bright conductive film forming process, sealing material adhesion process, etc.

■There should be no elution of dissolved substances into the liquid crystal or swelling of the filter membrane due to contact with the liquid crystal. That is, sufficient liquid crystal resistance is required.

■Since it is often used outdoors, sufficient light resistance is required.

- Sufficient adhesion to substrates (transparent substrates such as glass and plastic).

■Appropriate spectrum and sufficient color resolution.

■The dimensional accuracy of the pattern must be sufficient.

Therefore, materials for color filters must be selected in consideration of the above required performance.

"Structure of the Invention" (Means for Solving the Problems) In view of the above-mentioned circumstances, the present invention is based on repeated research to develop an ink for intaglio or intaglio offset that forms a high-quality, low-cost color filter. As a result, we provide an ink suitable for intaglio or intaglio offset printing that forms a color filter layer with excellent heat resistance, light resistance, chemical resistance, solvent resistance, adhesion to substrates, and spectral properties. It is something.

That is, one aspect of the present invention is an intaglio or intaglio offset printing ink composition for color filters containing an epoxy resin, a solvent, and a pigment as main components.

Next, we will describe the characteristics required of the ink materials for color filters, that is, the inks that are resins, solvent-based pigments, and mixtures thereof, and will also explain in detail the composition of the ink for color filters discovered by the present invention. explain.

In principle, the resin that can be used in the present invention is required to be colorless and transparent, and to have heat resistance, chemical resistance, solvent resistance, liquid crystal resistance, and light resistance.
In addition, sufficient adhesion to the substrate is required. However, if the resin is slightly colored to pale yellow, it can be used as a red and green binder resin due to its spectral characteristics. As a result of detailed comparative studies of various binder resins based on such required performance, it was found that epoxy resin satisfies all of the above required performances as a binder resin for color filters. For example, the characteristics of epoxy resins when compared with thermosetting resins such as polyester resins, phenolic resins, urea resins, and melamine resins as binders are that 1-reaction shrinkage during curing is extremely small, and volatile substances are eliminated. Since this does not occur, pattern reproducibility is good and cracks and turbidity are less likely to occur. In addition, the mechanical properties of the cured film are not only excellent.

Because it has adhesive properties on many materials such as glass, plastic, and metal, it is possible to directly form strong patterns not only on glass substrates but also on various transparent plastic substrates, transparent conductive substrates, etc., making it compatible with various liquid crystal cell configurations. Has characteristics.

Epoxy resins that can be used in the present invention are not particularly limited as long as they have little coloring and are soluble in solvents having alcoholic hydroxyl groups, but in particular bisphenol type, novolak type and cycloaliphatic type epoxy resins can be used alone. Alternatively, combination use is desirable. Various types of bisphenol-type epoxy resins are commercially available, ranging from low-molecular-weight ones that are liquid at room temperature to high-molecular-weight ones that are solid.

The viscosity can be adjusted over a wide range by selecting the molecular weight.

Novolanc type epoxy resins are generally strongly colored and are not preferred when used alone, but when combined with bisphenol type or cycloaliphatic type epoxy resins, they have the effect of improving their heat resistance and chemical resistance. Cycloaliphatic epoxy resins have somewhat poor adhesive strength, but have excellent light resistance and are particularly suitable for outdoor use. As described above, color filters using epoxy resin as a binder have the great feature that they can meet various required characteristics and can be formed on various substrates.

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

■Bisphenol type epoxy resin Epicoat 815.819.827.828.832
．． 834°1001, 1002.1004.100? ,
1009.1010 (Oilified shell epoxy ■) ■ Novolak type epoxy resin Epicor) 152.154 (Oilified shell epoxy ■) etc. ■ Cycloaliphatic type epoxy resin Chissonok 71. 201.221.289.206
．． Pigments that can be used in the present invention, such as 207X (Chisso ■), have heat resistance,
Pigments are desirable because chemical resistance, solvent resistance, liquid crystal resistance, and light resistance are required. 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 relative to visible light. 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, a niegu, or a two-roll mill. It is also useful to improve transparency and absorption coefficient.

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

C, 1, yellow pigment 24.86.93.94.108.
109°110, 11? , 125.137.138.
147°153, 154.166, 168 C,1, orange pigment 36.43.51.55.59
．． 6IC, 1, red pigment 97.122.123.14
9.168.177゜178, 180.187.190
．． 192.209°215, 216 or 217.22
0.223°224, 226.227.228.240
C, t, violet pigment 19.23.29.30.
37°40, 50°C, 1, blue pigment 15.15:1.15:3.15:
4.15:622, 60.64 C,1, green pigment 7,36 C,1, brown pigment 23.25.26C,1, black pigment 7 The solvent that can be used in the present invention dissolves the epoxy resin,
It is also necessary to select a material that does not dry out due to evaporation on the plate or blanket during printing. Furthermore, when a blanket is used as in intaglio offset, or when a transparent plastic substrate other than glass is used, materials that dissolve or swell these materials cannot be used because they reduce pattern reproducibility and transparency. As a result of detailed study from this viewpoint, 1. The solvent that can be used in the present invention has at least one alcoholic hydroxyl group and has a boiling point of 1.
It has been found that a mixed solvent of one or more selected from aliphatic alcohols, preferably polyhydric alcohol derivatives, having a temperature of 20 to 260° 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 motuptyl ether.

Ethylene glycol monohexyl ether.

Ethylene glycol heptanoacetate Methoxymethoxyethanol.

Diethylene glycol.

Diethylene glycol monomethyl ether.

Diethylene glycol monoethyl ether.

Diethylene glycol monobutyl ether.

Diethylene glycol heptanoacetate Triethylene glycol monomethyl ether.

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.

1-Butoxyethoxypropanol.

Among these solvents, those with low boiling points are combined with those with high boiling points, and those with high boiling points are combined with those with low boiling points to adjust the drying rate. 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 manufactured simply by kneading the resin, pigment, and solvent described above.

However, 1. For example, in order to print three-color patterns of red, green, and blue on the same substrate with the same film thickness under constant printing conditions, the nonvolatile content of each color ink and the printability of the ink must be made as close as possible. is desirable. In general, when using the same resin face, different pigments will have different ink flow characteristics, and furthermore, the pigment content of each color that provides the optimum spectrum will differ, resulting in large differences in the ink properties of each color. This can be adjusted to some extent by changing the type or composition of the resin or solvent for each color, but this complicates ink production.

In such cases, it is effective to add extender pigments or dispersion aids. By adding a small amount of extender pigment, it is possible to impart appropriate thixotropy and improve printability such as transferability. Note that as extender pigments that can be used in the present invention, fine powders of materials with relatively low refractive index such as silicon oxide, barium sulfate, and calcium carbonate are used in order not to impair transparency.Dispersion aids are used to disperse pigments. It has the effect of improving properties and preventing re-aggregation of pigments.
It has effects such as lowering thixotropy, lowering ink viscosity, improving transmittance, and improving coating film smoothness. Therefore, by combining the two-body pigment and the dispersion aid, it is possible to make the printability of each color ink similar. However, 9 extender pigments improve transparency, dispersion aids provide chemical resistance,
In order to reduce the solvent resistance, they are added as necessary, and it is preferable that the amount of each added in the ink is kept at 5% by weight or less.

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, organic dye derivatives are used. Organic pigment derivatives are derivatives of organic pigments or dyes, such as azo, phthalocyanine, quinacridone, anthraquinone, perylene, perinone, thioindigo, dioxazine, and isoindolinone.

It is a compound having 1 to 4 substituents in a quinophthalone-based, triphenylmethane-based, or metal complex salt-based organic dye compound. Substituents include hydroxyl and carboxyl groups.

These are sulfonic acid groups, carbonamide groups, etc., and substituents represented by the following general formula.

-CH2-X-A (x: oxygen or sulfur atom, A naryl group) R.

-CH2OXN Rt (X: alkylene group, R+, Rz: hydrogen atom, alkyl group, or a heterocycle containing at least a nitrogen atom in R1 and Rt) R.

HIN R.

(R,: alkyl group or aryl group.

R2: alkyl group or aryl group.

Or R, and R2 are less (Heterocycle containing a nitrogen atom) (R3: hydrogen atom, alkyl group.

A: Alkylene group.

R2: alkyl group, alkoxyalkyl or cycloalkyl group.

R3: an alkyl group or a cycloalkyl group, or a heterocycle containing at least a nitrogen atom in R2 and R8. Note that the organic pigment and the parent organic pigment of the derivative are usually the same in terms of hue, but they are not necessarily the same. There is no need to have done so.

The production of color filter ink is basically the same as the production method of normal printing ink. That is, the face is prepared by heating and melting the epoxy resin in a solvent under an inert gas flow. Next, a pigment and, if necessary, an extender pigment or a dispersion aid are added to this face, and the ink is sufficiently kneaded using a dispersing machine such as one roll or the like, for example, to produce an ink. The ink can obtain sufficient mechanical strength and adhesive strength for practical use simply by heating it at 1-80 to 200°C for several hours, but if even higher resistance is required or if the curing process is to be streamlined, known methods may be used. It is also possible to add hardeners.

Examples include low molecular weight amine compounds, melamine resins, urea resins, phenol resins, and the like. However, since amine curing agents significantly shorten pot life, it is desirable to add them immediately before printing. Examples of curing agents that can be added during ink production and have a long pot life include organic acid anhydrides and organic acid prebath metals. Although the ink of the present invention is mainly composed of epoxy resin, other resins can also be used in combination.

Example 1 600 g of diethylene glycol monobutyl ether and 400 g of ethylene glycol monobutyl ether were placed in a 31 separable flask, heated and stirred while passing nitrogen gas, and at about 100°C, Epicoat 1007 was gradually added in several portions. The temperature was raised to ℃, and after complete melting, the mixture was left to cool to produce a festival.

Next, a pigment and, if necessary, a dispersion aid, an extender pigment and a solvent were added to this face, and the mixture was sufficiently milled using three rolls to produce red, green, and blue inks, respectively. In addition, the formulation of the three-roll kneaded meat was carried out as follows for each color.

Here, the extender pigment is Aerosil R-972 (Nippon Aerosil ■), and the solvent is diethylene glycol motsubutyl ether and ethylene glycol motsubutyl ether in 6=4 (
(weight ratio) was used.

The compositions of the pigments and dispersion aids for each color are shown below, and the same pigments and dispersion aids were used from Example 2 onwards.

(For red filter) ■Pigment Lionogen Red GD (C01 manufactured by Toyo Ink Manufacturing ■)
Mixture of 70 parts of Pigment Red 168) with 30 parts of Onogen Orange R (manufactured by Toyo Ink Manufacturing ■, C.1, Pigment Orange 36) ■Dispersion aid Compound of the following structural formula (for green filter) ■Pigment Lionol Green 2YS (C manufactured by Toyo Ink Manufacturing Co., Ltd.)
1. Pigment Green 36) 75 parts Mixture with 25 parts of Onogen Ero-3G (C, 1, Pigment Yellow 154 manufactured by Toyo Ink Mfg. ■Dispersion aid The following low chlorinated copper phthalocyanine derivatives (for blue filters) ■Pigment Mixture of 80 parts of Lionol Blue ES (C01, Pigment Blue 15:6, manufactured by Toyo Ink Manufacturing ■) and 20 parts of Onogen Violet RL (C,1, Pigment Violet 23, manufactured by Toyo Ink Manufacturing ■) ■Example of dispersion aid 2 In the same manner as in Example 1, add Epicoat 1010 90 to a mixed solvent of 800 g of diethylene glycol monoethyl ether and 200 g of ethylene glycol monoethyl ether.
0g and 600g of Epicoat 1001 were dissolved to prepare a face, and three rolls were kneaded with the following formulation to produce inks of each color.

Here, the extender pigment is Aerosil R-972 (Nippon Aerosil ■), and the solvent is diethylene glycol monoethyl ether and ethylene glycol motubutyl ether.
:1 (weight ratio) was used.

Example 3 Epikote 1004 1 was added to a mixed solvent of 400 g of diethylene glycol monoethyl ether and 600 g of propylene glycol monoethyl ether in the same manner as in Example 1.
050g and 450g of Ebiko) 154 were dissolved to produce a festival, and the mixture was kneaded with three rolls according to the following formulation to produce inks of each color.

Here, the extender pigment is transparent pigment BF-1 (Sakai Chemical ■),
The solvent is diethylene glycol monoethyl ether and propylene glycol monobutyl ether in a ratio of 4:6 (
(weight ratio) was used.

Example 4 500 g of diethylene glycol monobutyl ether and 50 g of methoxymethoxyethanol were prepared in the same manner as in Example 1.
750g of Chissonox CX221 in 0g of mixed solvent
, Epicoat 1007 600g Oyohi Epicoat 15
4 Dissolve 150g to make a festival and make 3 with the following composition.
This roll was kneaded to produce ink of each color.

Here, the extender pigment is transparent pigment BF-10 (Sakai Chemical),
The solvent used was a mixture of diethylene glycol motsubutyl ether and methoxymethoxyethanol at a ratio of 1:1 (weight ratio).

[Manufacture of color filters]

FIG. 1 shows a perspective view for explaining the outline of printing on a base material with an intaglio plate using the ink of the present invention.

Intaglio (150μm x 150/1m dot matrix,
The ink prepared in Example 1 was applied on the plate depth 15 μm) (1).
After applying 2) and scraping off the excess ink (2) with a doctor (3), use a blanket (4) to transfer the ink on the intaglio (1) to transfer paper, glass substrate (1° 1 mm thick Sin,
Transfer the ink onto the glass substrate (5) by moving the blanket (4) onto the coated soda glass (5). By repeating this operation for each color line, a pattern of red, green, and blue as shown in Figure 2 (enlarged view) is created with a size of 50 mm x
It was formed over a size of 50 mm. This pattern was heat-treated at 200° C. for 1 hour to produce a color filter having the following characteristics.

■Spectral characteristics: Shown in Figure 3 ■Film thickness: 3 to 4 μm ■Heat resistance: Change in spectral transmittance within 5% in 1 hour at 220°C ■Light resistance: Xenon is passed through a polarizing filter The lamp was irradiated for 120 hours.

Change in spectral transmittance within 5% ■Chemical resistance/solvent resistance...Results from immersion or ultrasonic cleaning are shown in Table 1 ■Dimension accuracy...Accuracy of 10 μm (blank below) Table 1 Note- Treatment method A: Ultrasound (38°C) for 30 minutes at 23-28°C
KHz) Treatment B: Immersed at 25° C. for 10 minutes These characteristics satisfied the required performance of color filters for various displays including liquid crystals.

Note that color filters were made using the same method using the inks prepared in Examples 2 and 3, and similar characteristics were obtained.

In addition, the plate depth of the intaglio plate was set to 10 μm, and the ink obtained in Example 4 was used to print in the same manner as above, and heat treatment was performed to obtain a color filter with a film thickness of 2 to 3 μm and similar characteristics. Ta.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an overview of printing, which is a step of creating a color filter using the ink of the present invention, and Fig. 2 is an enlarged view showing the state in which red, green, and blue patterns are formed on a base material. , and FIG. 3 are graphs showing the spectral characteristics of a color filter obtained using the ink of the present invention.

Claims (1)

[Scope of Claims] 1. An intaglio or intaglio offset printing ink composition for color filters, which contains an epoxy resin, a solvent, and a pigment as main components. 2. The ink composition according to claim 1, wherein the dye is a pigment. 3. The ink composition according to claim 1, wherein the solvent is one or a mixed solvent of two or more aliphatic compounds having at least one alcoholic hydroxyl group.