JPH1184123A - Pigment dispersion type water-based ink for production of color filter and production of color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high injection stability and high productivity and to decrease color irregularity in pixels by incorporating a specified proportion of a pigment as a coloring agent and using a mixture of a glycol-based solvent, glycerin and water as a solvent and a specified alkylene oxide compd. as a dispersant. SOLUTION: For a pigment dispersion type water-based ink for the production of a color filter by ink-jet method, a coloring agent containing 1 to 5 wt.% of a pigment is used. As for the solvent, at least either a glycol-based solvent or glycerin is mixed with water and used. As a dispersant, an alkylene oxide compd. expressed by the formula of R<1> -(R<2> -O-)m -(R<3> -O-)n -H is used. In the formula, R<1> is a satd. or unsatd. hydrocarbon group, R<2> , R<3> are different from each other and are 2 to 3C alkylene groups, (m), (n) are O or positive integers satisfying 5<=m+n<=30, and the mol.wt. of the compd. is <=2000.

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 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 In recent years, with the development of personal computers, the color display of liquid crystal display devices has increased, and color filters have been used for that 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. As a method of manufacturing this color filter, a pigment dispersion method using a photolithography process capable of patterning with high precision is currently the mainstream.

Since this pigment dispersion method uses a photolithographic technique, an expensive photoresist is used, or each step of coating, drying, exposing, developing, and curing the resist is repeated three times for each color. Will be. For this reason, there has been a problem that a large-scale facility 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 Ink jet apparatuses have been rapidly spread in recent years as office and personal use paper printers because the apparatuses are small and simple, low in noise, low in running cost, and easy to colorize.

In recent years, there has been an increasing demand for a low-cost color image output device for printing on paper, and a technical means to meet this demand is to use an ink using a water-soluble dye for ink jet printing. It was common to obtain a color image by a printer.

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 these effects. For this reason,
It is expected that a pigment having high robustness will be used as a colorant for a recording liquid for inkjet recording.

[0007]

However, when an ink using a pigment is ejected by an ink jet apparatus, the ink near the nozzle dries, that is, the solvent in the ink volatilizes, causing the pigment to aggregate and settle. There is a problem that clogging is easily caused.

To solve this problem, see, for example, Japanese Patent Laid-Open No. 6-2
A method is generally known in which a water-soluble organic solvent having a high boiling point and excellent in moisture retention, such as 71797, is added to ink to suppress the volatilization of the solvent. However, general pigment dispersants are difficult to stably disperse in both water and water-soluble organic solvents. For this reason, when the ink jet device is left in a state where it is not ejected, water in the ink volatilizes preferentially, and the solvent component in the ink contains more organic solvent than water, resulting in aggregation of the pigment and increase in viscosity. Therefore, the ejection stability was not sufficient.

In addition to this problem, when a color filter is manufactured by an ink-jet method, the cross section of the pixel tends to be convex, and the peripheral portion of the pixel is thinner than the central portion, and the color tends to be thinner. There was a problem. One of the causes is that when ink is ejected by the inkjet method and lands on the substrate, its shape is maintained in a hemispherical shape due to surface tension, but then the solvent in the ink dries and the convex shape is relaxed. It is presumed that the viscosity of the ink increases and the fluidity of the ink decreases before the cross-sectional shape of the pixel becomes completely flat.

[0010] The present invention solves the above problems, has high ejection stability even when ejected continuously for a long time, has high productivity,
It is an object of the present invention to obtain an ink suitable for manufacturing a color filter by an inkjet method with less color unevenness in a pixel and a method for manufacturing a color filter using the same.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to be used as a colorant in a pigment-dispersed aqueous ink for producing a color filter for producing a color filter by an ink-jet method. A pigment is contained in an amount of 1 to 5% by weight, at least one of a glycol-based solvent and glycerin is mixed with water as a solvent, and an alkylene oxide compound represented by the general formula (1) is used as a dispersant (where R ¹ is saturated or R ² and R ³ are different from each other and have 2 carbon atoms.
Or 3 means an alkylene group, m and n are each 0 or a positive integer, 5 ≦ m + n ≦ 30, and the molecular weight is 2000 or less. The present invention provides a pigment-dispersed water-based ink for producing a color filter, characterized by using (1). R ^1- (R ² -O-) _m- (R ³ -O-) _n -H (1)

A pigment-dispersed aqueous ink for producing a color filter, wherein R ¹ is an aromatic group, and a viscosity of 100 cP or less when the solid content becomes 20 wt% by drying the ink. Provided is a pigment-dispersed aqueous ink for producing a color filter.

Further, the present invention provides a method for manufacturing a color filter, wherein a color filter is manufactured on a substrate by an ink-jet method using the pigment-dispersed aqueous ink for manufacturing a color filter.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The pigment-dispersed aqueous ink of the present invention comprises a pigment and a dispersant of a specific alkylene oxide compound represented by the general formula (1) in a mixed solvent of at least one of a glycol solvent and glycerin and water. It is possible to stably produce a color filter having excellent uniformity and a flat pixel cross-sectional shape continuously for a long time by an ink-jet method.

[0015] In the present invention, since it can be stably dispersed in a glycol solvent or both glycerin and water,
In the process of drying the solvent in the ink, even if only a specific solvent volatilizes quickly, aggregation of the pigment is suppressed, and a color filter with high transmittance can be obtained.

That is, after the ink is ejected onto the substrate by the ink jet method, the water in the ink tends to volatilize rapidly at room temperature, leaving a glycol solvent or glycerin having a high boiling point. Also in this case, in the case of the pigment-dispersed aqueous ink of the present invention, since the dispersant of the general formula (1) is used, the pigment can be stably dispersed in water, a glycol solvent, or glycerin. For this reason, aggregation of the pigment in the ink drying process is suppressed, and a bright color filter having a substantially uniform color distribution in the pixel can be obtained.

As the pigment used as a coloring agent in the present invention, various organic or inorganic pigments can be used. For example, azo pigments such as azo lake pigments, insoluble azo pigments, condensed azo pigments, chelated azo pigments, phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindoline pigments, isoindolinone pigments, Polycyclic pigments such as quinophthalone pigments, basic dye lakes, acid dye lakes, nitro pigments, nitroso pigments, aniline black,
Organic pigments such as daylight fluorescent pigments, and inorganic pigments such as titanium oxide, iron oxide, and carbon black.

Although these coloring pigments vary depending on the structure, those having a relatively small particle size are preferable, and the maximum particle size is 5%.
Those having a maximum particle size of not more than 00 nm, preferably not more than 200 nm are used.

The type of these pigments may be selected so as to obtain a desired color, and is used alone or in a mixture of 1 to 5% by weight based on the ink. If it is less than 1 wt%, the color becomes too light, the amount of ink increases, and uneven drying tends to occur. On the other hand, if it exceeds 5 wt%, the viscosity of the ink becomes high, and the ejection by the inkjet becomes unstable.

As the dispersant used in the present invention, an alkylene oxide compound represented by the following general formula (1) is used.
However, in the formula, R ¹ represents a saturated or unsaturated hydrocarbon group, R ² and R ³ are different from each other, and represent an alkylene group having 2 or 3 carbon atoms, and m and n are each 0 or positive. Where 5 ≦ m + n ≦ 30 and the molecular weight is 200
0 or less. R ^1- (R ² -O-) _m- (R ³ -O-) _n -H (1)

By using the dispersant of the general formula (1), the pigment can be dispersed with good dispersibility in water, a glycol solvent or glycerin. For this reason, the ink is unlikely to be convex even during drying after the ink is ejected, and the color uniformity within the pixel is improved. Further, stains as pigment aggregates are hardly generated in the vicinity of the nozzle of the inkjet head, and stable ejection can be performed for a long time.

The used amount of this dispersant is 0.2 to 10% by weight based on the ink. By adding in this range, the dispersibility of the pigment is improved and uniform coloring is easily obtained. Specific examples of R ¹ include an alkyl group, an alkenyl group, a phenyl group, a bifevir group, a phenylalkyl group, a naphthyl group, and a naphthylalkyl group. Particularly, when R ¹ contains a benzene ring, a naphthalene ring or the like,
Alkylene oxide adducts, which are monovalent aromatic groups, are preferred because of their good dispersibility.

As the aqueous solvent of the ink in the present invention, water and a glycol solvent or glycerin are used. As the water, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions.

Examples of the glycol solvent include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, thiodiglycol, hexylene glycol, and diethylene glycol. is there.

Among these glycol solvents or glycerin, the use of ethylene glycol, diethylene glycol, or glycerin in terms of moisture retention, viscosity, and boiling point makes it possible to perform stable inkjet discharge without causing clogging. It is easy for uniformed color filters to be uniform.

These glycol solvents or glycerin are used in an amount of 3 to 30% by weight, more preferably 5 to 15% by weight, based on the ink. When the content is less than 3 wt%, the drying speed of the ink is increased, and clogging is likely to occur at the time of ink ejection. If it exceeds 30% by weight, the viscosity of the ink will increase, the state of the ink droplets will tend to be unstable, and the productivity will decrease. More preferably, it is 5 to 15 wt%.

A binder component can be added to the ink of the present invention in order to enhance the reliability of a color image. Examples of the binder include an emulsion such as an acrylic resin, an epoxy resin, and a melamine resin, a water-soluble resin such as polyvinyl acetal, a water-soluble monomer such as 2-hydroxyethyl (meth) acrylate, and a water-soluble oligomer. These can be cured by heat or light after being discharged onto the substrate. This binder is 0
-10 wt%.

[0028] The extender can also be added at 0 to 5 wt%. As the extender, conventionally used pigments such as colloidal silica, calcium carbonate, alumina white, precipitated barium sulfate, barite powder, aluminum hydroxide, kaolin clay, and nepheline sinite can be used. As the material, colloidal silica, calcium carbonate, alumina white, and precipitated barium sulfate are preferable. The mixing amount of the extender is preferably smaller than the mixing amount of the binder.

The ink of the present invention may contain an anionic surfactant, a cationic surfactant, an amphoteric surfactant or a nonionic surfactant, if necessary. This surfactant is used in an amount of 0 to 2% by weight based on the ink.

Examples of the anionic surfactant include higher fatty acid salts, alkyl sulfates, alkyl ether sulfates, alkyl ester sulfates, alkyl allyl ether sulfates, alkyl sulfonates, sulfosuccinates, alkyl allyls and alkyl naphthalene sulfonic acids. Salt, alkyl phosphate, polyoxyethylene alkyl ether phosphate,
And alkyl allyl ether phosphate.

Examples of the cationic surfactant include an alkylamine salt, a dialkylamine salt, a tetraalkylammonium salt, a benzalkonium salt, an alkylpyridinium salt and an imidazolinium salt. Examples of the amphoteric surfactant include dimethyl alkyl lauryl betaine, alkyl glycine, alkyl di (aminoethyl) glycine, and imidazolinium bedine.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, sucrose ester, polyoxyethylene ether of glycerin ester, and sorbitan. There are polyoxyethylene ether of ester, polyoxyethylene ether of sorbitol ester, fatty acid alkanolamide, polyoxyethylene fatty acid amide, amine oxide, polyoxyethylene alkylamine and the like.

In the present invention, in addition to water and a glycol-based organic solvent or glycerin, other water-soluble organic solvents can be used in combination. The other water-soluble organic solvent is used in a smaller amount than the glycol-based solvent and glycerin used, and is in a range that does not adversely affect the performance of the ink.

Examples of optional solvent components that can be used in combination include alkyl alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol, dimethylformamide, Amides such as dimethylacetamide, ketones or ketone alcohols such as acetone and diacetone alcohol, ethylene glycol monomethyl (or ethyl, butyl) ether, diethylene glycol monomethyl (or ethyl, butyl) ether, propylene glycol monomethyl (or ethyl, butyl) And alkyl ethers such as ether.

In addition, 0 to 2% by weight of commonly used additives for inks such as an antifoaming agent, a preservative, a pH adjuster, and an ultraviolet absorber may be added.

It is preferable that the ink of the present invention is such that the viscosity of the ink when the solid concentration in the ink becomes 20 wt% during the drying of the ink is 100 cP or less. By doing so, it becomes difficult for the ink discharged on the substrate to become convex in the pixel when drying, and the color tends to be uniform in the pixel. In addition, even if the ink dries slightly near the nozzles of the ink jet head, pigment aggregates are unlikely to adhere and stable ejection for a long time becomes possible.

The ink thus adjusted is discharged by an ink jet method to form a color filter. At this time, a convex portion that serves as a partition wall is formed on the substrate in advance, and ink is ejected to the concave portion separated by the convex portion by an inkjet method, and the ink is deposited in the concave portion to form a colored layer. Is preferred.

When a pigment-based ink is used, the pigment is not adsorbed on the substrate surface. If there is no partition wall, the discharged ink flows out or scatters to the surrounding pixels, and the color purity is reduced. Therefore, it is preferable to form a projection on the substrate as a partition wall in advance.

The protrusions may be formed on the substrate in a linear or lattice shape. The shape of the convex portion may be such that the concave portion divided thereby corresponds to the pixel. For example,
When a stripe-shaped color filter is formed, it is formed in a linear shape, and is formed in a lattice shape in order to correspond to a square pixel. In a liquid crystal display device or the like, it is advantageous that the convex portion also serves as a light shielding film. Specifically, the protrusions may be formed using a black material, a metal light-shielding layer, or the like.

The projections play a role in preventing the discharged ink from flowing into other pixels or bleeding when colored by the ink jet method. Therefore, it is preferable that the height of the convex portion is somewhat high,
Since it is also required that the overall flatness of the color filter is high, a height close to the thickness of the coloring layer is selected. Usually, it may be about 0.1 to 2 μm. Also,
This width is usually slightly larger than the width between pixels so that a displacement or the like does not occur in a subsequent process and does not affect display.

The ink discharged in this manner is usually dried and baked at 150 to 300 ° C. Further, an insulating film such as a resin is formed on the color filter to flatten or improve the adhesiveness with the electrode, and the electrode is formed thereon. The liquid crystal display device may be formed by combining the color filter substrate thus formed and another substrate with electrodes.

[0042]

Embodiments of the present invention will be described below in detail. The parts shown below are parts by weight unless otherwise specified.
Further, the following naphthalene alkylene oxide adduct is a compound in which R ¹ is a β-naphthyl group (C ₁₀ H ₇ —), R ² is an ethylene group (—C ₂ H ₄ —), m = 11, and n = 0. means.

(1) Preparation of Red Pigment Dispersion (A) Pigment (Pigment Red 177) 20.0 parts Naphthalene alkylene oxide adduct 15.0 parts Diethylene glycol 3.0 parts Ion-exchanged water 62.0 parts And disperse in a ball mill for 20 hours.
Further, coarse particles were removed by centrifugation.

(2) Preparation of Green Dispersion (A) Pigment (Pigment Green 36) 20.0 parts Naphthalene alkylene oxide adduct 12.5 parts Monoethylene glycol 7.0 parts Ion-exchanged water 60.5 parts The above components are mixed. The mixture was dispersed in a sand mill for 7 hours, and filtered under pressure through a membrane filter to remove coarse particles.

(3) Preparation of Blue Dispersion Pigment (Pigment Blue 15: 6) 20.0 parts Naphthalene alkylene oxide adduct 17.0 parts Monoethylene glycol 5.0 parts Ion-exchanged water 58.0 parts The mixture was dispersed in a sand mill for 5 hours, and filtered under pressure through a membrane filter to remove coarse particles.

(4) Preparation of Red Dispersion (B) Pigment (Pigment Red 177) 20.0 parts Styrene-maleic acid copolymer 15.0 parts (neutralized with ammonia, active ingredient 30%) Diethylene glycol 3.0 parts 62.0 parts of ion-exchanged water The above components were mixed and dispersed in a ball mill for 20 hours.
Further, coarse particles were removed by centrifugation.

(5) Preparation of Green Dispersion (B) Pigment (Pigment Green 36) 20.0 parts Styrene-maleic acid copolymer 12.5 parts Monoethylene glycol 7.0 parts Ion-exchanged water 60.5 parts Were dispersed in a sand mill for 7 hours, and filtered under pressure through a membrane filter to remove coarse particles.

The preparation of the ink was adjusted to a predetermined concentration by adding the following components to the respective color dispersions.

Example 1 (Example) Red dispersion liquid (A) 16.76 parts Dodecylbenzenesulfonic acid monoethanolamine 0.15 parts Ion-exchanged water 73.09 parts Ethylene glycol 9.00 parts Monoethanolamine 1.00 parts

Example 2 (Example) Green dispersion (A) 19.61 parts Monoethanolamine dodecylbenzenesulfonate 0.15 part Ion-exchanged water 70.24 parts Ethylene glycol 9.00 parts Monoethanolamine 1.00 part

Example 3 (Example) Blue dispersion 16.04 parts Monoethanolamine dodecylbenzenesulfonate 0.15 parts Ion-exchanged water 73.81 parts Ethylene glycol 9.00 parts Monoethanolamine 1.00 parts

Example 4 (Example) Red dispersion liquid (A) 16.76 parts Monoethanolamine dodecylbenzenesulfonate 0.15 part Ion-exchanged water 67.09 parts Ethylene glycol 15.00 parts Monoethanolamine 1.00 part

Example 5 (Example) Red dispersion liquid (A) 16.76 parts Dodecylbenzenesulfonic acid monoethanolamine 0.02 parts Deionized water 77.28 parts Ethylene glycol 5.00 parts Monoethanolamine 1.00 parts

Example 6 (Comparative Example) Red Dispersion (B) 16.76 parts Dodecylbenzenesulfonic acid monoethanolamine 0.02 parts Deionized water 73.22 parts Ethylene glycol 9.00 parts Monoethanolamine 1.00 parts

Example 7 (Comparative Example) Green Dispersion (B) 19.61 parts Monoethanolamine dodecylbenzenesulfonate 0.15 part Ion-exchanged water 70.24 parts Ethylene glycol 9.00 parts Monoethanolamine 1.00 part

The ink thus obtained was ejected to a substrate by an ink jet method and measured. In Tests 1 and 2, the discharge was performed on a mere glass substrate and measured. In Tests 3 and 4, a color filter was produced by discharging a glass substrate in which a projection as a partition wall was formed in a portion other than the pixel in advance by a light-shielding layer. The results are shown in Tables 1 and 2.

Regarding the ejection stability, in Test 1, a constant ejection pulse (frequency 1 kHz) was intermittently applied at a cycle of 2.5 seconds to eject ink, and a solid amount corresponding to 5 drops of ink ejected from the orifice was measured. The sedimentation was measured. The ratio of the discharged liquid amount at the start of the test to the discharged liquid amount 20 hours after the start of the test is 1) 95% or more ◎ 2) 90% or more and less than 95% ○ 3) 70% or more Δ4) When less than 70% or when the liquid was not discharged, it was evaluated as ×.

Test 2 which is the second test of discharge stability
Is a method in which a constant ejection pulse (frequency 1 kHz) is intermittently applied at a cycle of 2.5 seconds to eject ink, and the distance between the ink droplet and the inkjet head 1 millisecond after the ink is ejected from the orifice is strobed. The discharge speed was determined by measuring with a camera. The ratio of the discharge speed at the start of the test to the discharge speed 20 hours after the start of the test is 1) 90% or more ○ 2) 70% or more and less than 90% △ 3) Less than 70% or liquid Was not discharged when no ink was ejected.

Test 3 is a test on the properties of the ink discharged on the substrate. After discharging the ink to the opening of the substrate provided with the light-shielding layer, the substrate was dried at 65 ° C. × 10 minutes.
Next, baking was performed at 230 ° C. for 1 hour to form a color filter. The step of the pixel of the color filter is measured by a laser microscope. 1) When the step is less than 0.03 μm ○ 2) When the step is 0.03 μm or more and less than 0.06 μm △ 3) The step is 0.06 μm or more When it was, it was evaluated as ×.

In Test 4, the color filters of Examples 2 and 7 prepared in Test 3 were used, and the chromaticity of the central portion of the pixels was measured using a microspectrophotometer (Otsuka Electronics, MCPD1000). The results are shown in Table 2 as xy (chromaticity coordinates in CIE1931) and Y values (stimulus values in CIE1931). Table 2 also shows the transmittance (%) for light of 515 nm.
Shown in

The viscosity at the time when the solid content concentration became 20 wt% was measured by a B-type viscometer (60 rpm, 25 ° C.) in Examples 2 and 7, and it was 45 cP in Example 2, The thing was 220 cP.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

As described above, when the pigment-dispersed water-based ink for producing a color filter of the present invention is used, the ink is dispersed in a wide range of solid content in response to a change in the solvent composition accompanying drying of the ink. It becomes possible. For this reason, even if the ink near the nozzle of the inkjet head dries,
Clogging of the nozzle due to aggregation of the ink is less likely to occur, and the ejection stability is excellent. This makes it possible to manufacture a color filter that is stable for a long time.

When drying the ink discharged on the substrate,
It is possible to obtain a color filter in which the pixel central portion is unlikely to be convex, the pixel cross-sectional shape is flat, and the color is uniform and bright in the pixel. The present invention can be applied to various applications within a range that does not impair the effects of the present invention.

Claims (4)

[Claims] 1. A pigment-dispersed aqueous ink for producing a color filter for producing a color filter by an ink-jet method, comprising 1 to 5% by weight of a pigment as a colorant and at least one of a glycol solvent and glycerin as a solvent and water. And an alkylene oxide compound represented by the general formula (1) as a dispersant (where R ¹ represents a saturated or unsaturated hydrocarbon group;
R ² and R ³ are different from each other and mean an alkylene group having 2 or 3 carbon atoms, m and n are each 0 or a positive integer, 5 ≦ m + n ≦ 30, and the molecular weight is 2000 or less. . A pigment-dispersed water-based ink for producing a color filter, characterized by using (1). R ^1- (R ² -O-) _m- (R ³ -O-) _n -H (1) 2. The pigment-dispersed aqueous ink according to claim 1, wherein R ¹ is an aromatic group. 3. The ink is dried to have a solid content concentration of 20 wt.
%. The pigment-dispersed water-based ink for producing a color filter according to claim 1, wherein the viscosity at 100% is 100 cP or less. 4. A method for producing a color filter, comprising producing a color filter on a substrate by an inkjet method using the pigment-dispersed aqueous ink for producing a color filter according to claim 1, 2 or 3.