JPH1121487A - Pigment-dispersing type aqueous ink and production of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink enabling continuous production of color filter by including a pigment, a polymer surfactant, an anionic surfactant, an organic amine, an organic solvent and water at a specific ratio. SOLUTION: This ink comprises (A) 1-5 wt.% pigment, (B) 0.2-7 wt.% polymer surfactant having aromatic ring (preferably benzene ring or naphthalene ring) and hydrophilic group (preferably carboxyl group, polyoxyethylene group or hydroxyl group) with 500-40,000 molecular weight, (C) 0.001-2 wt.% anionic surfactant having <500 molecular weight, (D) 0.5-8 wt.% organic amine of the formula NR<1> R<2> R<3> (R<1> to R<3> are each independently H, a 1-4C hydroxyalkyl, with the proviso that at least one among R<1> to R<3> is not H) (preferably ethanol amine), (E) an organic solvent and (F) water. Dispersibility of pigment is improved and discharge which is stable for a long period in ink jet method can be performed by using the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pigment-dispersed aqueous ink for producing a color filter by an ink-jet method and a method for producing a color filter.

[0002]

2. Description of the Related Art The color display of liquid crystal display devices has been increasing with the recent development of personal computers, and color filters have been used for this purpose. This color filter is 800 × 600 at a pitch of about 100 × 300 μm.
It is necessary to form fine color filters such as × 3 pixels or 1024 × 768 × 3 pixels. For this reason, formation by the pigment dispersion method is now mainstream.

[0003] Since the pigment dispersion method is a method using a photolithography technique, an expensive photoresist is used, and each step of coating, drying, exposing, developing, and curing the resist is repeated three times. Become. For this reason, there has been a problem that a huge amount of capital investment is required, the productivity is low due to the photolithography process, and the price of the obtained color filter is high.

[0004] For this reason, an ink-jet method has been attracting attention as a method of manufacturing a color filter with a simple manufacturing apparatus and high productivity. 2. Description of the Related Art Inkjet apparatuses have been rapidly spread in recent years as office and personal use paper printers because the apparatuses are small and simple, have low noise, have low running costs, and are easy to colorize.

In recent years, there has been a great demand for a low-cost color image output device for this printer, and as a technical means to meet this demand, a color image is formed by an ink jet printer using an ink using a water-soluble dye. It was common to get.

However, in the case of a color image, if one of a plurality of colors has poor water fastness or light fastness, the quality of the color image may be extremely deteriorated due to the influence of the poor water fastness or light fastness. Is expected to be used for inkjet recording.

[0007]

However, when a pigment ink is ejected by an ink jet apparatus, the ink near the nozzle dries, that is, the solvent in the ink volatilizes, so that the pigment agglomerates and sediments, and the nozzle becomes clogged. There was a problem that occurred. For this reason, there was a problem that the dye ink having low durability had to be relied on.

The present invention solves these problems, is a pigment ink having good weather resistance, is an aqueous ink that is easy to handle, hardly causes nozzle clogging, and is suitable for a continuous production of a color filter. It is an object to provide a water-based ink and a color filter manufacturing method.

[0009]

According to the present invention, there is provided a pigment-dispersed aqueous ink for producing a color filter by an ink-jet method, comprising 1 to 5% by weight of a pigment and a molecular weight of 500 to 500 having an aromatic ring and a hydrophilic group. a polymeric surfactant from 0.2 to 7 wt% of the 40000, the anionic surfactant from 0.01 to 2 wt% of molecular weight below 500, the general formula NR ¹
Organic amines represented by R ² R ³ (R ¹ , R ² , R
³ is each independently a hydrogen atom or a hydroxyalkyl group having 1 to 4 carbon atoms, and R ¹ , R ² and R ³ may be the same or different. At least one of R ¹ , R ² and R ³
One is not a hydrogen atom. A) a pigment-dispersed aqueous ink comprising 0.5 to 8% by weight, and an organic solvent and water as a solvent;

Further, the polymer surfactant provides the above pigment-dispersed aqueous ink in which the aromatic ring is a benzene ring or a naphthalene ring, and the hydrophilic group is a carboxyl group, a polyoxyethylene group or a hydroxyl group. Further, the above-mentioned pigment-dispersed aqueous ink is provided, wherein the anionic surfactant is an organic sulfate having 6 or more carbon atoms or an organic sulfonate having 6 or more carbon atoms.

Further, in a color filter manufacturing method for manufacturing a color filter by ejecting ink from a plurality of ink jet nozzles using a pigment-dispersed aqueous ink, a method for manufacturing a color filter comprising a pigment, an aromatic ring and a hydrophilic group having a molecular weight of 500 to 500
40,000 polymeric surfactants, anionic surfactants having a molecular weight of less than 500, and organic amines represented by the general formula NR ¹ R ² R ³ (R ¹ , R ² , and R ³ each independently represent a hydrogen atom or a carbon atom. A hydroxyalkyl group of Formulas 1 to 4,
R ¹ , R ² and R ³ may be the same or different. At least one of R ¹ , R ² and R ³ is not a hydrogen atom. ), Using a pigment-dispersed water-based ink containing an organic solvent and water, surrounded by a light-shielding film weir in which the water repellency of at least the upper surface of the light-shielding film is higher than the water-repellency of the surface of the pixel region where the light-shielding film is not provided. A method for manufacturing a color filter, characterized by ejecting ink to a pixel region. Also,
The present invention provides the above-mentioned method for producing a color filter, wherein the above-mentioned pigment-dispersed aqueous ink is used as the pigment-dispersed aqueous ink.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The pigment-dispersed aqueous ink of the present invention comprises a pigment, an aromatic ring and a hydrophilic group, a high molecular surfactant having a molecular weight of 500 to 40,000 and an organic solvent and water, and a molecular weight of less than 500. And an organic amine represented by the general formula NR ¹ R ² R ³ , and a color filter can be manufactured with high uniformity by an inkjet method.

In the present invention, a pigment is used as a coloring agent. As the pigment, an organic or inorganic pigment can be used. The type of the pigment may be selected so as to obtain a desired color, and may be used alone or as a mixture at 1 to 5% by weight based on the ink. 1
If the amount is less than the weight percentage, the color becomes too light, the amount of ink increases, and drying unevenness easily occurs. If it exceeds 5% by weight, clogging is likely to occur during ink ejection, and the yield tends to decrease.

The high molecular surfactant used in the present invention has a molecular weight of 500 to 400 having an aromatic ring and a hydrophilic group.
00 polymeric surfactants are used. The used amount is 0.2 to 7% by weight based on the ink. By adding in this range, the dispersibility of the pigment is improved, and uniform coloring is easily obtained.

Specifically, a polymeric surfactant having an aromatic ring such as a benzene ring or a naphthalene ring and a hydrophilic group such as a carboxyl group or a hydroxyl group and having a molecular weight of 500 to 40,000 is used. In particular, a compound having a benzene ring or a naphthalene ring as an aromatic ring and a carboxyl group, a polyoxyethylene group or a hydroxyl group as a hydrophilic group is preferable because of good dispersibility.

As a specific example, for example, a styrene-acrylic acid copolymer or a styrene-maleic acid copolymer having a molecular weight of 1500 to 40000, or a compound having a plurality of oxyethylene groups connected to a naphthalene ring and having a hydroxyl group at a terminal is used. And those having a molecular weight of 500 to 1,000.

In the present invention, an anionic surfactant having a molecular weight of less than 500 is used in an amount of 0.01 to 2% by weight based on the ink. If the amount is less than 0.01% by weight, clogging is likely to occur at the time of ink ejection. If the amount exceeds 2% by weight, the surface tension of the ink is reduced, the state of ink droplets tends to be unstable, and the production yield is likely to be reduced. More preferably 0.05
To 0.5% by weight.

Examples of the anionic surfactant include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl aryl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl aryl sulfonates, and the like. Alkyl naphthalene sulfonate, alkyl phosphate, polyoxyethylene alkyl ether phosphate, alkyl aryl ether phosphate and the like.

When an organic sulfate having 6 or more carbon atoms or an organic sulfonate having 6 or more carbon atoms is used among these anionic surfactants, clogging hardly occurs and stable ink jet discharge can be performed. Filters tend to be uniform.

In the present invention, the organic amine represented by the general formula NR ¹ R ² R ³ is used in an amount of 0.5 to 8% by weight based on the ink. If the amount is less than 0.5% by weight, clogging due to evaporation of the solvent in the ink is likely to occur at the time of ink ejection, and 8% by weight
If the amount is more than 1, the dispersion stability of the pigment is reduced.

The R in the general formula NR ¹ R ² R ^3
1 , R ² and R ³ each independently represent a hydrogen atom or a carbon number of 1 to 4;
(Preferably having 2 to 4 carbon atoms) a hydroxyalkyl group. R ¹ , R ² and R ³ may be the same or different. At least one of R ¹ , R ² and R ³ is not a hydrogen atom. As the organic amine represented by the general formula NR ¹ R ² R ³ , monoethanolamine, diethanolamine, and triethanolamine are preferable.

In addition to the above, in the present invention, a binder component can be added to enhance the reliability of the colored layer formed by discharging. Examples of the binder include emulsions such as acrylic resin, epoxy resin and melamine resin, water-soluble resins such as polyvinyl acetal, water-soluble monomers such as 2-hydroxyethyl (meth) acrylate and polyethylene glycol diacrylate, and water-soluble oligomers. These can be cured by heat or light after the ink is discharged onto the substrate.

In the present invention, a solid component containing the pigment, a high molecular surfactant having an aromatic ring and a hydrophilic group and having a molecular weight of 500 to 40,000 and an anionic surfactant having a molecular weight of less than 500 is contained in an amount of 1.21%. It is preferable to set it to 15% by weight. If the content is less than 1.21% by weight, the color becomes too thin and color unevenness is likely to occur. If the content is more than 15% by weight, ejection from the inkjet head tends to be unstable.

The solid component is more preferably 2 to 8% by weight. If the content is less than 2% by weight, the color becomes lighter, so it is necessary to increase the number of ink droplets, and the productivity tends to decrease. 8
If the amount is more than 10% by weight, it becomes difficult to adjust the viscosity of the ink to an optimum value for inkjet.

The solid component may contain the above-mentioned binder component and additives such as an antifoaming agent and a preservative, if necessary. It should be noted that a pigment having a molecular weight of 5 having an aromatic ring and a hydrophilic group
A polymer surfactant having a molecular weight of from 00 to 40,000 and an anionic surfactant having a molecular weight of less than 500 have a solid content of 100%.
% By weight, at least 40% by weight or more, more preferably 80% by weight or more.

The non-solid component is represented by the general formula NR ¹ R ² R
^The organic amine represented by ³ contains an organic solvent and water. The non-solid components hardly remain in the color filter formed by volatilization during heat curing. In addition, you may add the additive which volatilizes at the time of heat hardening and does not remain after to a non-solid component.

It is preferable to use ion-exchanged water (deionized water) as water as a solvent. Other arbitrary organic solvents that can be used in combination may be appropriately selected from the following organic solvents and used.

Alkanols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol and tert-butanol; amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; Ketone alcohols, polyalkylene glycols such as polyethylene glycol and polypropylene glycol,
Alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl (or ethyl, butyl) ether, diethylene glycol monomethyl (or ethyl, butyl) ether, propylene glycol monomethyl (or ethyl,
Alkyl ethers such as butyl) ether, thiodiglycol, and glycerin.

Of these many water-soluble organic solvents,
Ethylene glycol, diethylene glycol, and glycerin are particularly preferred from the viewpoint of the boiling point, moisture retention, and the like. The content of the organic solvent in the ink of the invention is preferably in the range of 1 to 60% by weight, more preferably in the range of 5 to 20% by weight based on the total weight of the ink.

The ink of the present invention in which the above components are mixed is used by being discharged from an ink jet head. In this case, in the production of a color filter, unlike printing on general paper or cloth, durability against light and heat is required, and the durability of a dye ink is insufficient. Therefore, a pigment ink is used. In this case, the medium from which the ink is ejected is a glass substrate or a plastic substrate, which is a material that does not normally absorb the water or solvent of the ink.

As in the case of printing on paper or cloth, even if ink is ejected on these substrates, it is not possible to print on the substrates neatly. That is, since the substrate does not absorb water or the solvent, when the ejected ink collides with the substrate surface, it scatters or flows out to the periphery, so that a desired colored pattern cannot be formed.

For this reason, a weir is formed beforehand around the pixel region where the colored layer is to be formed on the substrate by a light-shielding film. By forming the weir in this way, the ejected ink can be made to remain in the pixel region surrounded by the weir. The light shielding film dam may itself be a thick light shielding film like a resin light shielding film, or may be a combination of a thin metal film such as chrome and a non-light shielding resin thick film. You may.

At this time, in this light shielding film, the water repellency of at least the upper surface of the light shielding film is made higher than the water repellency of the surface of the pixel region where the light shielding film is not provided. This makes it difficult for the ink to protrude onto the light shielding film.

The water repellency may be provided by the following method. Water repellency may be imparted to the material of the light shielding film itself. Further, after forming a light-shielding film using a light-shielding film material having no or low water repellency, the surface of the light-shielding film may be subjected to a water-repellent treatment. In the latter case, as the process, a method of performing water repellency treatment on the entire surface to reduce the water repellency of only the pixel region can be adopted.

The color filter may be manufactured by scanning the ink jet head relative to the substrate to obtain a desired colored pattern. If the number of nozzles is small,
A scanning method in which scanning is performed in the X and Y directions and if the number of nozzles is large, scanning in only one direction per line can be used.

Normally, three colors of RGB are formed by three scans. However, if an ink jet head capable of forming three colors simultaneously can be used, it can be manufactured by one scan. Further, if the color filter itself has two colors, the scanning may be performed twice.

Further, if necessary, the color filter substrate is formed through drying and curing steps of the ink. An inorganic film such as SiO ₂ and TiO ₂ and a resin film such as an acrylic resin, an epoxy resin, and a silicon resin are formed thereon as necessary.
A conductive film such as ITO is formed and used.

The color filter substrate with the conductive film formed in this way and another substrate with the conductive film are arranged so that the electrode surfaces are opposed to each other, and liquid crystal is sealed between them. It is a display element. In this case, if necessary, an inorganic film such as SiO ₂ or TiO ₂ or a polyimide,
A resin film of polyamide or the like is provided, their surfaces are subjected to horizontal alignment processing by rubbing, or vertical alignment processing by aminosilane.

Various known liquid crystals can be used as the liquid crystal. Specifically, a nematic liquid crystal is a typical liquid crystal, but a smectic liquid crystal or another liquid crystal may be used.
A guest-host type liquid crystal mixed with a coloring dye may be used.

[0040]

Embodiments of the present invention will be described below in detail. The abbreviations for each component are shown in Table 1. Each component was mixed at a composition ratio shown in Table 2 (unit: parts by weight; for PSMA1, PSMA2, and PSAA, the total weight parts of the active ingredient and the medium component substantially consisting of water), and a red pigment dispersion was prepared. R is dispersed in a ball mill for 20 hours and further subjected to centrifugation treatment. The green pigment dispersion G ₁ and the green pigment dispersion G ₂ are dispersed in a sand mill for 7 hours, and then pressure-filtered with a membrane filter. The blue pigment dispersion B is 5
The dispersion was performed for a time, followed by filtration under pressure with a membrane filter to remove coarse particles.

The ink was prepared by adding each component at a composition ratio (unit: parts by weight) shown in Tables 3 and 4 using the respective color dispersions thus obtained. The following tests were performed by applying the obtained inks of Examples 1 to 13 (of which Examples 11 to 13 were comparative examples) to an ink jet head. The results are also shown in Tables 3 and 4.

Test 1: Constant discharge pulse (frequency 1 kHz)
z) was applied intermittently at a cycle of 2.5 seconds to eject ink, and the solid deposition amount of 5 drops of ink ejected from the orifice was measured. When the ratio of the amount of solids deposited 20 hours after the start of the test to the amount of solids deposited at the start of the test was 95% or more, it was evaluated as “◎” and 90% or more.
When it was less than 5%, it was evaluated as “○”, when it was 70% or more and less than 90%, it was evaluated as “Δ”, and when it was less than 70% or the liquid was not discharged, it was evaluated as “X”.

Test 2: Constant discharge pulse (frequency 1 kHz)
z) was applied intermittently at a cycle of 2.5 seconds to eject the ink, and the distance between the ink droplet and the ink jet head 1 ms after the ink was ejected from the orifice was determined by a strobe camera. When the ratio of the discharge speed (distance) after 20 hours from the start of the test to the discharge speed (distance) at the start of the test is 90% or more, "O" is given, and when the ratio is 70% or more and less than 90%. "△"
And “×” when less than 70% or when the liquid was not discharged.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

1 μm thick black resin on a glass substrate
Was formed around the pixel region by photolithography. This light-shielding film is coated with black resin on the entire surface,
After treating the upper surface with a fluorine-based water-repellent agent, patterning is performed by a photolithography method, and 800 ×
It was formed around a pixel area of 600 × 3 colors.

Using the three colors of RGB of Examples 1, 2 and 4, ink was supplied to the ink jet head, and the ink jet head was relatively moved in two directions perpendicular to the glass substrate on which the light shielding film was formed. Scan it and add 3
The process was repeated twice to form a color filter.

An acrylic resin was placed on the color filter substrate.
An epoxy-based flattening layer was formed, and a transparent conductive film of ITO was further formed. This ITO was patterned in a stripe shape, an insulating layer of SiO ₂ —TiO ₂ was formed, and a polyimide layer was formed and rubbing was performed.

On another substrate, a transparent conductive film made of ITO is formed in the same manner, and the ITO is patterned in a stripe shape, an insulating layer of SiO ₂ —TiO ₂ is formed, and a polyimide layer is further formed. Rubbing was performed.

These two substrates were spaced apart such that the polyimide layers faced each other, and the periphery was sealed with a sealing material to form empty cells. A nematic liquid crystal is injected into the empty cell, and a retardation plate and a polarizing plate are arranged to form a color S.
TNLCD was made.

[0053]

By using the ink for inkjet of the present invention, the dispersibility of the pigment is improved, clogging due to evaporation of the solvent around the nozzle can be suppressed, and stable ejection can be performed for a long time. Become. This allows
A color filter can be manufactured with a high yield. The present invention
Various applications are possible without impairing the effects of the present invention.

Claims (5)

[Claims] 1. A pigment-dispersed aqueous ink for producing a color filter by an ink-jet method.
-5% by weight and a molecular weight of 50 having an aromatic ring and a hydrophilic group.
0.2 to 7% by weight of polymer surfactant of 0 to 40,000
And an anionic surfactant having a molecular weight of less than 500 0.01
To 2% by weight and an organic amine represented by the general formula NR ¹ R ² R ³ (wherein R ¹ , R ² and R ³ are each independently a hydrogen atom or a hydroxyalkyl group having 1 to 4 carbon atoms; ¹ ,
R ² and R ³ may be the same or different. R
^At least one of ¹ , R ² and R ³ is not a hydrogen atom. A) a pigment-dispersed aqueous ink comprising 0.5 to 8% by weight, and an organic solvent and water as a solvent. 2. The polymer surfactant, wherein the aromatic ring is a benzene ring or a naphthalene ring, the hydrophilic group is a carboxyl group,
The pigment-dispersed aqueous ink according to claim 1, which is a polyoxyethylene group or a hydroxyl group. 3. The pigment-dispersed aqueous ink according to claim 1, wherein the anionic surfactant is an organic sulfate having 6 or more carbon atoms or an organic sulfonate having 6 or more carbon atoms. 4. A color filter manufacturing method for manufacturing a color filter by discharging ink from a plurality of inkjet nozzles using a pigment-dispersed aqueous ink.
Molecular weight 500 to 40,000 having an aromatic ring and a hydrophilic group
, An anionic surfactant having a molecular weight of less than 500, and an organic amine represented by the general formula NR ¹ R ² R ³ (R ¹ , R ² and R ³ each independently represent a hydrogen atom or a carbon atom 1 to 4 hydroxyalkyl groups, R ¹ , R
² and R ³ may be the same or different. R ¹ ,
At least one of R ² and R ³ is not a hydrogen atom. ),
Using an organic solvent, and a pigment-dispersed aqueous ink containing water,
A method of manufacturing a color filter, comprising discharging ink to a pixel region surrounded by a weir of a light-shielding film in which the water repellency of at least the upper surface of the light-shielding film is higher than the water repellency of the surface of the pixel region where the light-shielding film is not provided. . 5. A pigment-dispersed aqueous ink as claimed in claim 1, 2 or 3.
5. The method for producing a color filter according to claim 4, wherein the pigment-dispersed aqueous ink according to claim 3 is used.