TITLE OF THE INVENTION

INK COMPOSITION FOR COLOR FILTER, METHOD FOR PREPARING

A COLOR FILTER USING THE SAME, AND COLOR FILTER BACKGROUND OF THE INVENTION (a) Field of the Invention

The present invention relates to an ink composition for a color filter, a method of perparing a color filter, and a color filter using the same. More particularly, the present invention relates to an ink composition for a color filter with excellent ejection properties and processibility, since it does not clog a nozzle during the printing, and also excellent heat resistance, chemical resistance, film hardness, storage stability, and close-contacting property of a pattern prepared by using it, a method of perparing a color filter, and a color filter provided in this method. (b) Description of the Related Art In general, a color filter is used for a liquid crystal display (LCD), an optical filter for a camera, and the like. It is fabricated by coating a fine region colored with more than three colors on a charge coupled device or a transparent substrate. Colored thin films can be commonly fabricated in dying, printing, electrophoretic deposition (EPD), pigment dispersion, and inkjet methods.

The dying forms a colored film by forming an image with a dying agent such as a natural photosensitive resin such as gelatin and the like, an amine-modified polyvinyl alcohol, an amine-modified acryl-based resin,

i

and the like on a substrate, and then dying the image with direct dyes. However, the dying process may become more complex and delayed, since it should include resist printing whenever a color needs to be changed to form a multicolored thin film on the same substrate. In addition, a commonly used dye and a resin themselves generally have good color vividness and dispersion but bad light fastness, water resistance, and heat resistance, which are very important characteristics.

The printing forms a colored thin film by printing an ink prepared by dispersing a pigment into a thermally curable or photocurable resin and curing it with heat or light. This method may decrease material cost compared with other methods, but has difficulty in forming a fine and exact image, and also in acquiring a uniform thin film layer. Korean laid-open patent Nos. 95-703746 and 96-11513 disclose a method of making a color filter in an inkjet method. However, it also has the same problem of deteriorated durability and heat resistance as the dying, since it also uses a dye-type color resist composition dispersed from a nozzle to accomplish fine and precise color printing.

Otherwise, Korean laid-open patent Nos. 93-7000858 and 96-29904 disclose electrophoretic deposition (EPD) using ah electric precipitation method. The electrophoretic deposition (EPD) can form a precise colored film that has excellent heat resistance and light fastness of the colored film, since it includes a pigment. However, when a finer electrode pattern is needed for a more sophisticated pixel in the future, it

can be difficult to apply the method to a color filter requiring high sophistication since a colored film may be stained or thicker at both ends due to electrical resistance.

The pigment dispersion method forms a colored film by repeating a series of processes such as coating, exposing to light, developing, and curing a photopolymer composition including a coloring agent on a transparent substrate with a black matrix. This pigment dispersion method can improve heat resistance and durability, which are very important characteristics of a color filter, and uniformly maintain the thickness of the film. In addition, it is generally adopted since it is not only easy to apply but can also accomplish a fine pattern. As examples, Korean laid-open patent Nos. 92-7002502 and 95-7000359 and Korean patent publication Nos. 94-5617 and 95-11163 disclose a method of making a color resist in this pigment dispersion method. However, this pigment dispersion method has a difficulty in managing a yield rate, since each color of red (R), green (G), and blue (B) respectively requires coating, exposure, development, and curing to form a pixel, which makes the whole process line longer and increases control factors among the processes. In addition, as electronics such as a monitor, TV, and the like require a high color resolution rate and a high contrast ratio, it may bring about several problems such as increasing the thickness of a coating layer and the like.

Accordingly, this conventional pigment dispersion method has

recently been replaced with several new methods. An inkjet printing method is representatively included in them. The inkjet printing method forms a light proof layer such as a black matrix and the like on a glass substrate and implants ink in the pixel space. This method does not require processes such as coating, exposure, development, and the like, and can thereby decrease necessary materials required for the processes and simplify the whole process line.

The inkjet method should form a color layer among pixels to have uniform and excellent color characteristics. Accordingly, a nozzle should not be clogged when ink is dispersed from its head. Further, the ink should be dispersed with the same amount and the same number of drops inside a pixel. The dispersion performance critically depends on interaction between the surface of the head nozzle and the color ink. In addition, when the ink is ejected, it should be prevented from overflowing into the opening of neighboring pixels and contaminating them.

Furthermore, when a pattern is formed in the inkjet method, it should have the same reliability as in a pigment dispersion method. It should also have heat resistance, chemical resistance, film strength, storage stability, and the like. When the pattern does not satisfy these characteristics, it may cause a problem of color change, damage, and the like during post-processes of a color filter. SUMMARY OF THE INVENTION

An exemplary embodiment of the present invention provides a color

filter ink composition with excellent ejection properties, since it does not clog a nozzle during the dispersion, and also has excellent heat resistance, chemical resistance, film strength, storage stability, and close-contacting property of the pattern. Another embodiment of the present invention provides a method of making the color filter ink composition.

Further embodiment of the present invention provides a color filter made from the ink composition.

The embodiments of the present invention are not limited to the above technical purposes, and a person of ordinary skill in the art can understand other technical purposes.

According to one embodiment of the present invention, provided is a color filter ink composition that includes an acryl-based copolymer resin represented by the following Formulae 1 to 3, a polymerizable monomer, a pigment, and a solvent.

[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

In the above Formulae 1 to 3, Ri to R ₃ and Rs to R ₈ are the same or independently selected from the group consisting of hydrogen and a substituted or unsubstituted linear or branched alkyl,

Ar ₁ and Ar ₂ are the same or independently selected from the group consisting of a substituted or unsubstituted aryl and a substituted or unsubstituted heteroaryl, ni and n ₂ are the same or independently an integer ranging from 1 to 5, e is an integer ranging from 1 to 10,

f is an integer ranging from 1 to 5, and a, b, and c are mole ratios of repeating units in a numerical range of 1 to 50.

Another embodiment of the present invention provides a method of making a color filter that includes coating the above color filter ink composition on a substrate using an inkjet spray method to form a pattern, and curing the pattern.

Another embodiment of the present invention provides a color filter fabricated using the color filter ink composition. Hereinafter, further embodiments of the present invention will be described in detail.

The color filter ink composition according to an embodiment of the present invention includes a novel acryl-based copolymer resin as a binder resin, and can thereby secure excellent ejection properties, ejection stability, and storage stability, so that it can be used for a long period. In addition, when the color filter ink composition is formed into a pattern, the pattern can have improved heat resistance, chemical resistance, and film strength.

DETAILED DESCRIPTION OF THE INVENTION Exemplary embodiments of the present invention will hereinafter be described in detail. However, these embodiments are only exemplary, and the present invention is not limited thereto.

Hereinafter, the components of a color filter ink composition

according to one embodiment of the present invention are illustrated in detail.

[Al Acryl-based copolymer resin

The acryl-based copolymer resin is a copolymer resin including a repeating unit represented by the following Formulae 1 to 3:

[Chemical Formula 1]

[Chemical Formula 2]

[Chemical Formula 3]

In the above formulae 1 to 3,

Ri to R3 and Rsto Rs are the same or independently selected from the group consisting of hydrogen and a substituted or unsubstituted linear or branched alkyl, and preferably hydrogen or -CH ₃ ,

API and Ar ₂ are the same or independently selected from the group consisting of a substituted or unsubstituted aryl and a substituted or unsubstituted heteroaryl, and preferably An and Ar ₂ are the same or independently selected from the group consisting of a substituted or unsubstituted C ₆ to C ₁₀ aryl and a substituted or unsubstituted C ₅ to C ₉ heteroaryl, wherein the substituted aryl and substituted heteroaryl preferably include a substituent selected from the group consisting of H, -CH ₃ , and -OC(CH ₃ ) ₃ , ni and n ₂ are the same or independently an integer ranging from 1 to 5, e is an integer ranging from 1 to 10, f is an integer ranging from 1 to 5, and a, b, and c are mole ratios of repeating units in a numerical range of 1 to 50.

The acryl-based copolymer resin may further include a repeating

unit represented by the following Formula 4. [Chemical Formula 4]

In the above formula 4, R ₄ is selected from the group consisting of hydrogen and a substituted or unsubstituted linear or branched alkyl,

R ₉ is selected from the group consisting of a substituted or unsubstituted linear or branched alkyl preferably an alkyl substituted with an alkoxy, a substituted or unsubstituted cycloalkyl, a substituted or

unsubstituted heterocycloalkyl, a norbomyl ( ^), and a substituted or unsubstituted alcohol, preferably a primary alcohol or a secondary alcohol, a substituted or unsubstituted alkylether, and glycidyl.

Examples of R ₉ are preferably selected from the group consisting of

-CH ₃ , -C ₂ H ₅ , -C ₄ H ₉ , -(CH ₂ ) ₃ CH ₃ , -CH ₂ CH(CH ₃ ) ₂ , -C(CH ₃ J ₃ , -CH ₂ CH(C ₂ H ₅ )C ₄ H ₉ , -CH2CH(CH3)CH ₂ CH(CH ₃ )CH2CH(CH3) ₂ , -Ci ₂ H ₂₅ ,

-Ci3H ₂ 7, -CuH ₂₉ , -C-15H31, -C16H33, -C17H3S, -C18H37, -C ₂ H ₄ OC ₄ H ₉ ,

-(CH ₂ CH ₂ O) ₂ C ₄ H ₉ , -(CH ₂ CH ₂ O) ₃ CH ₃ , -(CH ₂ CH ₂ O) ₉ CH ₃ , ^" O ₁ ^" U ₁

-~*-\J _f norbornyl, -CH ₂ CH ₂ OH, -CH ₂ CH(OH)CH ₃ , -CH ₂ CH(OH)CH ₃ ,

-CH ₂ CH(OH)CH ₂ CH ₃ , and glycidyl, and d is 0.1 to 50 mol% based on the acryl-based copolymer, and preferably 1 to 45 mol%.

In the present specification, when specific definition is not provided, the term "substituted" refers to one substituted with at least a substituent selected from the group consisting of a hydroxy, a halogen, a substituted or unsubstituted linear or branched alkyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted heterocycloalkyl, a substituted or unsubstituted alkoxy, a substituted or unsubstituted aryl, a substituted or unsubstituted heteroaryl, and a substituted or unsubstituted alkenyl, and is preferably selected from the group consisting of a substituted or unsubstituted linear or branched alkyl, a substituted or unsubstituted aryl, a substituted or unsubstituted heterocycloalkyl, and a substituted or unsubstituted alkoxy. In the present specification, when specific definition is not provided,

"an alkyl" refers to a C ₁ to C ₃₀ alkyl and preferably a Ci to C-iβ alkyl, "a cycloalkyl" refers to a C ₃ to C ₂₀ cycloalkyl and preferably a C ₃ to C10 cycloalkyl, "a heterocycloalkyl" refers to a C ₂ to C ₂ o heterocycloalkyl and preferably a C ₂ to C-io heterocycloalkyl, "alkoxy" refers to a Ci to C ₂ o alkoxy, preferably a Ci to do alkoxy, and more preferably a Ci to C ₄ alkoxy, "an aryl" refers to a CQ to C4 ₀ aryl and preferably a Cβto C ₂ o aryl, "a heteroaryl" refers to a C ₂ to C ₃ o heteroaryl and preferably a C ₂ to dβ heteroaryl, "an alkenyl" refers to a C ₂ to C ₂ o alkenyl and preferably a C ₂ to Ci ₀ alkenyl, "an

alcohol" refers to a Ci to C2 ₀ alcohol, preferably a Ci to C ₁₀ alcohol, and more preferably a Ci to C ₅ lower alcohol, and "an alkylether" refers to a C ₂ to C _2O alkylether and preferably a C ₂ to C-io alkylether.

The "heterocycloalkyl" or "heteroaryl" refer to a cycloalkyl and an aryl including 1 to 20, preferably 1 to 15, and more preferably 1 to 5 heteroatoms selected from the group consisting of N, O, S, and Si.

The acryl-based copolymer resin, which includes a repeating unit represented by the above Formulae 1 to 3, and selectively a repeating unit represented by Chemical Formula 4, has no copolymer limit, but can be a block copolymer including regularly repeated repeating units or a random copolymer including randomly repeated repeating units.

In addition, the acryl-based copolymer resin, which includes a repeating unit represented by the above Formulae 1 to 3, and selectively, a repeating unit represented by Chemical Formula 4, can be prepared in additional polymerization by radical initiation of a styrene-based compound or an acryl-based compound.

The styrene-based compound or acryl-based compound includes styrene, 4-methyl styrene, 4-butoxy styrene, 1 -methyl styrene, 1 -methyl 4'-methyl styrene, 1 -methyl 4'-butoxy styrene, methyl acrylate, ethyl acrylate, n-butyl acrylate, iso-butyl acrylate, t-butyl acrylate, 2-ethyl hexyl acrylate, isodecyl acrylate, n-lauryl acrylate, n-tridecyl acrylate, myristyl acrylate, pentadecyl acrylate, cesyl acrylate heptadecyl acrylate, stearyl acrylate, n-butoxy ethyl acrylate, butoxy diethyleneglycol acrylate, methoxy

triethyleneglycol acrylate, methoxy nonylethyleneglycol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, isobonyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, glycidyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethyl hexyl methacrylate, isodecyl methacrylate, n-lauryl methacrylate, n-tridecyl methacrylate, myristyl methacrylate, pentadecyl methacrylate, cesyl methacrylate, heptadecyl methacrylate, stearyl methacrylate, n-butoxy ethyl methacrylate, butoxy diethyleneglycol methacrylate, methoxy triethyleneglycol methacrylate, methoxy nonylethyleneglycol methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, isobonyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, glycidyl methacrylate, 2-acryloyl, oxyethyl succinic acid, 2-acryloyldioxyethyl succinic acid, 2-acryloyltrioxyethyl succinic acid, 2-acryloyltetraoxyethyl succinic acid, 2-acryloylpentaoxyethyl succinic acid,

2-methacryloyloxyethyl succinic acid, 2-methacryloyldioxyethyl succinic acid, 2-methacryloyltrioxyethyl succinic acid, 2-methacryloyltetraoxyethyl succinic acid, 2-methacryloylpentaoxyethyl succinic acid, 2-phenoxy ethyl acrylate, 2-phenoxy diethyleneglycol acrylate, 2-phenoxy triethyleneglycol acrylate, 2-phenoxy tetraethyleneglycol acrylate, 2-phenoxy pentaethyleneglycol acrylate, 2-phenoxy hexaethyleneglycol acrylate, 2-phenoxy heptaethyleneglycol acrylate, 2-phenoxy octaethyleneglycol

acrylate, 2-phenoxy nonaethyleneglycol acrylate, 2-phenoxy decaethyleneglycol acrylate, 2-phenoxy ethyl methacrylate, 2-phenoxy diethyleneglycol methacrylate, 2-phenoxy triethyleneglycol methacrylate, 2-phenoxy tetraethyleneglycol methacrylate, 2-phenoxy pentaethyleneglycol methacrylate, 2-phenoxy hexaethyleneglycol methacrylate, 2-phenoxy heptaethyleneglycol methacrylate, 2-phenoxy octaethyleneglycol methacrylate, 2-phenoxy nonaethyleneglycol methacrylate, 2-phenoxy decaethyleneglycol methacrylate, 2-phenoxy ethyl acrylate, 2-phenoxy diethyleneglycol acrylate, 2-phenoxy triethyleneglycol acrylate, 2-phenoxy tetraethyleneglycol acrylate, 2-phenoxy pentaethyleneglycol acrylate, 2-phenoxy hexaethyleneglycol acrylate, 2-phenoxy heptaethyleneglycol acrylate, 2-phenoxy octaethyleneglycol acrylate, 2-phenoxy nonaethyleneglycol acrylate, 2-phenoxy decaethyleneglycol acrylate, 2-phenoxy ethyl methacrylate, 2-phenoxy diethyleneglycol methacrylate, 2-phenoxy triethyleneglycol methacrylate, 2-phenoxy tetraethyleneglycol methacrylate, 2-phenoxy pentaethyleneglycol methacrylate, 2-phenoxy hexaethyleneglycol methacrylate, 2-phenoxy heptaethyleneglycol methacrylate, 2-phenoxy octaethyleneglycol methacrylate, 2-phenoxy nonaethyleneglycol methacrylate, 2-phenoxy decaethyleneglycol methacrylate, 2-(t-butyl)phenoxy ethyl acrylate, 2-(t-butyl)phenoxy diethyleneglycol acrylate, 2-(t-butyl)phenoxy triethyleneglycol acrylate, 2-(t-butyl)phenoxy tetraethyleneglycol acrylate, 2-(t-butyl)phenoxy pentaethyleneglycol

acrylate, 2-(t-butyl)phenoxy hexaethyleneglycol acrylate,

2-(t-butyl)phenoxy heptaethyleneglycol acrylate, 2-(t-butyl)phenoxy octaethyleneglycol acrylate, 2-(t-butyl)phenoxy nonaethyleneglycol acrylate, 2-(t-butyl)phenoxy decaethyleneglycol acrylate, 2-(t-butyl)phenoxy ethyl methacrylate, 2-(t-butyl)phenoxy diethyleneglycol methacrylate, 2-(t-butyl)phenoxy triethyleneglycol methacrylate, 2-(t-butyl)phenoxy tetraethyleneglycol methacrylate, 2-(t-butyl)phenoxy pentaethyleneglycol methacrylate, 2-(t-butyl)phenoxy hexaethyleneglycol methacrylate, 2-(t-butyl)phenoxy heptaethyleneglycol methacrylate, 2-(t-butyl)phenoxy octaethyleneglycol methacrylate, 2-(t-butyl)phenoxy nonaethyleneglycol methacrylate, 2-(t-butyl)phenoxy decaethyleneglycol methacrylate, and combinations thereof.

The acryl-based copolymer resin may have a weight average molecular weight (Mw) ranging from 3000 to 15,000. In another embodiment, it may have a weight average molecular weight ranging from 5000 to 10,000. When it has a weight average molecular weight of less than 3000, it may bring about a problem of a slow curing rate and a non-uniform coating surface. However, when it has a weight average molecular weight of over 15,000, it may have too high a viscosity to be uniformly coated.

In addition, the acryl-based copolymer resin may have an acid value of less than 100 KOHmg/g. In another embodiment, it may have an acid value ranging from 10 to 100 KOHmg/g. When it has an acid value

within the range, the ink composition may have excellent developability and improved stability.

The acryl-based copolymer resin may be included in an amount ranging from 1 to 40 wt% based on the total amount of a color filter ink composition. When it is included in an amount of less than less than 1 wt%, an ink composition may not be coated in a uniform thickness or be strongly adhered to a substrate, deteriorating a color filter post-process such as film strength, heat resistance, chemical resistance, after-image, and the like. When it is included in an amount of more than 40 wt%, it may increase viscosity of an ink composition, so that the ink composition may clog a nozzle and not be uniformly ejected. FBI Polymerizable Monomer

The polymerizable monomer is a monomer generally used in a color filter photosensitive resin composition, such as dipentaerythrytol hexaacrylate, ethyleneglycol diacrylate, triethyleneglycol diacrylate, 1 ,4-butanediol diacrylate, 1 ,6-hexanediol diacrylate, neopentylglycol diacrylate, pentaerythrytol diacrylate, pentaerythrytol triacrylate, dipentaerythrytol diacrylate, dipentaerythrytol triacrylate, dipentaerythrytol pentaacrylate, pentaerythrytol hexaacrylate, bisphenol A diacrylate, trimethylolpropane triacrylate, novolace poxyacrylate, ethyleneglycol dimethacrylate, diethyleneglycol dimethacrylate, triethyleneglycol dimethacrylate, propyleneglycol dimethacrylate, 1 ,4-butanediol dimethacrylate, 1 ,6-hexanediol dimethacrylate, and so on.

The polymerizable monomer may be included in an amount of 1 to

20 wt% based on the total amount of a color filter ink composition. When it is included in an amount of less than 1 wt%, it may cause a film to not be sufficiently cured after the pattern formation, deteriorating film strength. When it is included in an amount of more than 20 wt%, it may cause a film to be excessively shrunk, and thereby detached from a black matrix, deteriorating reliability of a color filter post-process. It may also increase viscosity of an ink composition and thereby deteriorate storage stability.

As a result, the ink composition may not have satisfactory ink characteristics.

[Cl Pigment

The pigment may be selected from the group consisting of an organic pigment, an inorganic pigment, and a combination thereof.

The organic pigment may include an anthraquinone-based pigment, a condensed polycyclic pigment such as a perylene-based one and the like, a phthalocyanine pigment, an azo-based pigment, and a combination thereof.

The organic pigment may particularly include a compound classified into a pigment in a color index. The color compound may include C.I. pigment yellow No. 1 , C.I. pigment yellow No. 12, C.I. pigment yellow No. 13, C.I. pigment yellow No. 14, C.I. pigment yellow No. 15, C.I. pigment yellow No. 16, C.I. pigment yellow No. 17, C.I. pigment yellow No. 20, C.I. pigment yellow No. 24, C.I. pigment yellow No. 31 , C.I. pigment

yellow No. 53, C.I. pigment yellow No. 83, C.I. pigment yellow No. 86, C.I. pigment yellow No. 93, C.I. pigment yellow No. 94, C.I. pigment yellow No. 109, C.I. pigment yellow No. 110, C.I. pigment yellow No. 117, C.I. pigment yellow No. 125, C.I. pigment yellow No. 128, C.I. pigment yellow No. 137, C.I. pigment yellow No. 138, C.I. pigment yellow No. 139, C.I. pigment yellow No. 147, C.I. pigment yellow No. 148, C.I. pigment yellow No. 150, C.I. pigment yellow No. 153, C.I. pigment yellow No. 154, C.I. pigment yellow No. 166, C.I. pigment yellow No. 173, C.I. pigment orange No. 13, C.I. pigment orange No. 31 , C.I. pigment orange No. 36, C.I. pigment orange No. 38, C.I. pigment orange No. 40, C.I. pigment orange No. 42, C.I. pigment orange No. 43, C.I. pigment orange No. 51 , C.I. pigment orange No. 55, C.I. pigment orange No. 59, C.I. pigment orange No. 61 , C.I. pigment orange No. 64, C.I. pigment orange No. 65, C.I. pigment orange No. 71 , C.I. pigment orange No. 73, C.I. pigment red No. 9, C.I. pigment red No. 97, C.I. pigment red No. 105, C.I. pigment red No. 122, C.I. pigment red No. 123, C.I. pigment red No. 144, C.I. pigment red No. 149, C.I. pigment red No. 166, C.I. pigment red No. 168, C.I. pigment red No. 176, C.I. pigment red No. 177, C.I. pigment red No. 180, C.I. pigment red No. 192, C.I. pigment red No. 215, C.I. pigment red No. 216, C.I. pigment red No. 224, C.I. pigment red No. 242, C.I. pigment red No. 254, C.I. pigment red No. 264, C.I. pigment red No. 265, C.I. pigment blue No. 15, C.I. pigment blue No. 15:3, C.I. pigment blue No. 15:4, C.I. pigment blue No. 15:6, C.I. pigment blue No. 60, C.I. pigment purple No.1 , C.I. pigment

purple No. 19, C.I. pigment purple No. 23, C.I pigment purple No. 29, C.I pigment purple No. 32, C.I pigment purple No. 36, C.I pigment purple No. 38, C.I. pigment green No. 7, C.I. pigment green No. 36, C.I. pigment brown No. 23, C.I. pigment brown No. 25, and the like. These organic pigments can be used singularly or as a combination of two or more.

The inorganic pigment may include titanium oxide, titanium black, carbon black, and a combination thereof.

The pigment should have high transmittance and a high contrast ratio. In addition, it should have a small particle size and a small particle size distribution. However, when its particle has too small an average diameter, it may deteriorate dispersibility. Accordingly, it should have an average particle diameter ranging from 0.01 to 0.5μm, but is not limited thereto.

The pigment may be included in an amount of 1 to 40 wt% based on the total amount of a color filter ink composition. In another embodiment, it may be included in an amount of 5 to 20 wt%. When it is included in an amount of less than 1 wt%, it may not accomplish desired color reproducibility. When it is include in an amount of more than 40 wt%, it may sharply deteriorate the pattern-curing characteristic and adherence to a substrate.

In addition, the pigment is dispersed into a solvent to prepare a pigment dispersion solution and can then be mixed with a color filter ink composition. The pigment dispersion solution can be prepared according

to a common method. fDl Solvent

The solvent may include any solvent, as long as it has high dissolubility for an acryl-based copolymer resin and excellent affinity for the pigment dispersion solution, and can thereby maintain high dispersibility. In another embodiment, it can be a high boiling-point solvent. The high boiling-point solvent may prevent a nozzle from being clogged during the printing, thereby securing the color characteristic of a color filter.

The high boiling-point solvent may have a boiling point ranging from 170 to 250 ⁰ C, but is not limited thereto.

The high boiling-point solvent is preferably selected from the group consisting of 3-methoxy butyl acetate, diethylene glycol methyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, ethylene glycol butyl ether acetate, 1 ,3-butanediol diacetate, propylene glycol n-propyl ether acetate, propylene glycol n-butyl ether acetate, dipropylene glycol n-propyl ether acetate, dipropylene glycol n-butyl ether acetate, propylene glycol diacetate, dipropylene glycol propyl ether, dipropylene glycol butyl ether, tripropylene glycol methyl ether, diethylene glycol dibutyl ether, tripropylene glycol butyl ether, and combinations thereof.

In addition, the solvent can be prepared by mixing a solvent with a boiling point of lower than 17O ⁰ C with the high boiling-point solvent in order to improve color reproducibility, contrast ratio, and storage stability required

for a color filter.

The low boiling-point solvent is preferably selected from the group consisting of ethylacetate, n-butylacetate, isobutylacetate, isopropylacetate, n-propylacetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, 3-methoxy-1 -propyl acetate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol propyl ether, propylene glycol diacetate, ethylene glycol propyl ether, n-butyl propionate, 3-ethoxy ethyl propionate, n-pentyl propionate, n-propyl propionate, propylene glycol methyl ether propionate, and combinations thereof.

The high boiling-point solvent may be mixed with the low boiling-point solvent in a weight ratio of 99:1 to 50:50. When the high boiling-point solvent is included at lower than the ratio, the solvent may be volatilized too fast and speed up drying an ink. Accordingly, the nozzle may be more frequently clogged, resulting in deteriorating ejection performance of the ink. When it is included at higher than the ratio, the ink may not be uniformly ejected and it may be difficult to maintain a high contrast ratio due to deteriorated dispersibility and storage stability.

The solvent can be included as a balance, but in another embodiment, in an amount of 40 to 90 wt% based on the total amount of a color filter ink composition. When it is included in an amount of less than 40 wt%, it may sharply deteriorate ejection properties of the ink, so that the ink cannot be printed. When it is included in an amount of more than 90

wt%, the ink may leak from a nozzle, thereby failing to acquire a desired color characteristic after the pattern formation.

[El Polymerization Initiator

The color filter ink composition may further include a polymerization initiator to improve pattern strength. The polymerization initiator may be selected from the group consisting of a photopolymerization initiator, a thermal polymerization initiator, and a combination thereof.

The photo polymerization initiator includes an acetophenone-based compound, a benzophenone-based compound, a thioxanthone-based compound, a benzoin-based compound, a triazine-based compound, or a combination thereof.

The acetophenone-based compound includes

2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone,

2-hydroxy-2-methylpropinophenone, p-t-butyltrichloroacetophenone, p-t-butyldichloroacetophenone, 4-chloroacetophenone,

2,2'-dichloro-4-phenoxyacetophenone, 2-methyl-1-

(4-(methylthio)phenyl)-2-morpholinopropan-1-one,

2-benzyl-2-dimethylamino-1- (4-morpholinophenyl)-butan-1-one, and so on. The benzophenone-based compound includes benzophenone, benzoyl benzoate, benzoyl methyl benzoate, 4-phenyl benzophenone, hydroxy benzophenone, acrylated benzophenone, 4,4'-bis(dimethyl amino)benzophenone, 4,4'-bis(diethylamino)benzophenone,

4,4'-dimethylaminobenzophenone, 4,4'-dichlorobenzophenone,

3,3'-dimethyl-2-methoxybenzophenone, and so on.

The thioxanthone-based compound includes thioxanthone,

2-crolthioxanthone, 2-methylthioxanthone, isopropyl thioxanthone, 2,4-diethyl thioxanthone, 2,4-diisopropyl thioxanthone,

2-chlorothioxanthone, and so on.

The benzoin-based compound includes benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyldimethylketal, and so on. The triazine-based compound includes 2,4,6,-trichloro s-triazine,

2-phenyl4,6-bis(trichloromethyl)-s-triazine,

2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-tria zine,

2-(4'-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazin e,

2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine,

2-biphenyl4,6-bis(trichloromethyl)-s-triazine, bis(trichloromethyl)-6-styryl-s-triazine,

2-(naphto1-yl)-4,6-bis(trichloromethyl)-s-triazine,

2-(4-methoxynaphto1-yl)-4,6-bis(trichloromethyl)-s-triazi ne, 2,4-trichloromethyl(piperonyl)-6-triazine,

2,4-trichloromethyl(4'-methoxystyryl)-6-triazine, and so on.

The photo polymerization initiator may further include a carbazole-based compound, a diketone-based compound, a sulfonium

borate-based compound, a diazo-based compound, a biimidazole-based compound, and the like.

The thermal polymerization initiator may include a generally-used peroxide-based compound. The peroxide-based compound includes methylethylketone peroxide; methylisobutyl ketone peroxide; cyclohexanone peroxide; acetylacetone peroxide; isobutyryl peroxide; and a hydroperoxide series compound such as diisoprobenzene hydroperoxide, cumenehydroperoxide, and t-butylhydroperoxide.

The thermal polymerization initiator includes peroxyketal series compounds such as 1 ,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 2,2-di-(t-butyloxyisopropyl)benzene, 4,4-di-t-butylperoxyvaleric acid n-butylester, and so on.

The polymerization initiator may be included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of a color filter ink composition. When the initiator is included in an amount of less than 0.1 parts by weight, it may not improve pattern strength. However, when it is included in an amount of more than 10 parts by weight, it may deteriorate storage stability and gradually increase viscosity, deteriorating ejection performance. rFl Other additives

The color filter ink composition may selectively include a dispersing agent to improve dispersion of a pigment.

The dispersing agent may include a non-ionic, anionic, or cationic

dispersing agent. For example, it may include polyalkylene glycol or an ester thereof, polyoxyalkylene, a polyhydric alcohol ester alkylene oxide additive, an alcoholalkyleneoxide additive, sulfonic acid ester, sulfonate, carboxylic acid ester, carboxylate, an alkylamide alkylene oxide additive, an alkylamine, and the like. These dispersing agents can be used singularly or as a combination of more than two. The dispersing agent may be included in an amount of 10 to 20 parts by weight based on 10 to 20 parts by weight of a pigment.

In addition, the ink composition may further include a silicon-based or fluorine-based coating improving agent to improve coating and defoamability, and also an adherence improving agent to improve its adherence to a substrate. The coating and adherence improving agents are included in an amount of 0.01 to 1 parts by weight based on 100 parts by weight of the ink composition. Another embodiment of the present invention provides a method of making a pixel for a display color filter using the color filter ink composition.

The method of making a pixel of a display color filter includes coating the ink composition on a substrate using an inkjet spraying method to form a pattern (S1 ), and curing the pattern (S2). Pattern Formation (SD

The color filter ink composition is coated to be 1.0 to 3.0μm thick on a substrate in an inkjet dispersion method. According to the inkjet dispersion, a pattern can be formed by repetitively dispersing desired

colors one by one or simultaneously dispersing the desired colors to simplify the process. Curing (S2)

The pattern is cured, acquiring a pixel. The curing may include optic curing, thermal curing, or the like. The thermal curing may be preferred. The thermal curing may be performed at a temperature of higher than 200 ⁰ C.

According to still another embodiment of the present invention, provided is a color filter prepared using the color filter ink composition. Hereinafter, the present invention is illustrated in more detail with reference to examples. However, they are exemplary embodiments of present invention and are no limiting.

Example 1 : Preparation of a color filter ink composition (A) Acryl-based copolymer resin of Chemical Formula 5: 4 wt% Weight average molecular weight: 6000

Monomer mole ratio: a/b/c = 40/30/30

[Chemical Formula 5]

(B) Polymerizable monomer: 4 wt% Dipentaerythrytol hexaacrylate

(C) Pigment: 10 wt%

C.I. pigment red No. 254 / C.I. pigment red No. 177 = 80:20 (weight ratio)

(D) Solvent

Diethylene glycol butyl ether acetate: 52 wt% Diethylene glycol ethyl ether acetate: 30 wt%

These above components were used to prepare an ink composition.

Example 2: Preparation of a color filter ink composition An ink composition was prepared according to the same method as Example 1 , except for using an acryl-based copolymer resin of the following Formula 6 instead of an acryl-based copolymer resin of Chemical

Formula 5.

(A) Acryl-based copolymer resin of Chemical Formula 6: 4 wt% Weight average molecular weight: 6000 Monomer mole ratio: a/b/c/d = 30/20/20/30 [Chemical Formula 6]

Example 3: Preparation of a color filter ink composition

An ink composition Example 3 was prepared according to the same method as Example 2, except for using 62 wt% of diethylene glycol butylether acetate and 20 wt% of propylene glycol methyl ether acetate instead of the solvent of Example 2.

Example 4: Preparation of a color filter ink composition An ink composition was prepared according to the same method as Example 3, except for using 10 wt% of C.I. pigment green No.36 and C.I. pigment yellow No.150 mixed in a weight ratio of 75:25 instead of the pigment of Example 3.

Example 5: Preparation of a color filter ink composition

An ink composition was prepared according to the same method as Example 3, except for using 10 wt% of C.I. pigment blue No. 156 and C.I. pigment purple No.23 mixed in a weight ratio of 90:10 instead of a pigment (C) of Example 3.

Example 6: Preparation of a color filter ink composition (A) Acryl-based copolymer resin of Chemical Formula 7: 2 wt% Weight average molecular weight: 6000 Monomer mole ratio: a: b: c: d = 30:10:20:40 [Chemical Formula 7]

(B) Polymerizable monomer: 5.5 wt% Dipentaerythrytolhexaacrylate

(C) Pigment: 10 wt%

C.I. pigment red No. 254: C.I. pigment red No. 177 = 80:20 (weight ratio)

(D) Solvent

Diethylene glycol butyl ether acetate: 52 wt% Diethylene glycol ethyl ether acetate: 30 wt%

(E) Polymerization initiator: 0.5 wt% TAZ-110 (Midori Chemical Co., Ltd.)

The above components were used to prepare an ink composition. Example 7: Preparation of a color filter ink composition An ink composition was prepared according to the same method as Example 6, except for using 62 wt% of diethylene glycol butyl ether acetate and 20 wt% of propylene glycol methyl ether acetate instead of the solvent (D) of Example 6.

Example 8: Preparation of a color filter ink composition An ink composition was prepared according to the same method as Example 7, except for an acryl-based copolymer resin of the following Formula 8 instead of the acryl-based copolymer resin of Example 7.

(A) Acryl-based copolymer resin of Chemical Formula 8: 4 wt% Weight average molecular weight: 8000 Monomer mole ratio: a: b: c: d= 40:10:20:30

[Chemical Formula 8]

Comparative Example 1 : Preparation of a color filter ink composition An ink composition was prepared according to the same as

Example 1 , except for using 4 wt% of benzyl methacrylate / cyclohexyl methacrylate / methacrylic acid copolymer mixed in a monomer mole ratio of 40:40:20 and having a weight average molecular weight of 30,000 instead of the acryl-based copolymer resin of Chemical Formula 6 according to Example 2.

Comparative Example 2: Preparation of a color filter ink composition

An ink composition was prepared according to the same as

Example 1 , except for using 4 wt% of benzyl methacrylate / cyclohexyl methacrylate / glycidyl methacrylate / methacrylic acid copolymer mixed in a monomer mole ratio of 30:30:20:20 and having a weight average molecular weight of 22,000 instead of the acryl-based copolymer resin of

Chemical Formula 6 according to Example 2.

Property evaluation of color filter ink compositions

The color filter ink compositions according to Examples 1 to 8 and Comparative Examples 1 to 2 were evaluated regarding properties as follows.

(1) Evaluation of ejection properties

The color filter ink compositions of Examples 1 to 8 and

Comparative Examples 1 to 2 were measured in a droplet size of 2OpL on a paper, and then ejected through all the nozzles three times. Then, their ejection amounts were measured, and the wetness degree around the nozzle was evaluated. The results are shown in the following Table 1.

Herein, © denotes an average ejection amount of 20±0.3pL and less than 2 wet nozzles; o denotes an average ejection amount of 20±0.5pL and less than 4 wet nozzles; δ denotes an average ejection amount of 20±0.7pl_ and less than 6 wet nozzles; and * denotes an average ejection amount of more than 20±0.7pL.

(2) Evaluation of long ejection properties

The color filter ink compositions of Examples 1 to 8 and Comparative Examples 1 to 2 were dispersed once, and after the passage of 10 seconds they were dispersed twice and 20 seconds were allowed to elapse, to form a droplet size of 2OpL on paper. Then, the waiting times were progressively increased and the droplets were examined until there was a non-uniform ejection from the nozzles. The results are shown in

the following Table 1.

Herein, ® denotes normal ejection despite a waiting time of over 300 seconds; o denotes normal ejection despite a waiting time ranging from 200 to 300 seconds; δ denotes normal ejection despite a waiting time ranging from 100 to 200 seconds; and * denotes normal ejection despite a waiting time of less than 100 seconds. In addition, when the ink was not ejected because one of the nozzles was clogged or the ink did not drop on a pixel even if it were ejected, these were categorized as bad.

(3) Heat resistance evaluation The color filter ink compositions of Examples 1 to 8 and

Comparative Examples 1 to 3 were printed to be 1 to 2μm thick on a black matrix substrate and dried at 22O ⁰ C for 40 minutes in a forced convection drying oven to form a pattern. This pattern was allowed to stand in a 22O ⁰ C forced convection drying oven for 1 to 3 hours, and was then photographed with an optical microscope by taking an optical picture. The optical picture was used to examine pattern changes with the naked eye. In addition, color difference was examined by measuring δE with a colorimeter. The results are shown in the following Table 1.

In the following Table 1 , o denotes no pattern change and color difference (δE) of less than 3.0; δ denotes a little pattern change or a color difference (δE) ranging from 3.0 to 5.0; and x denotes much pattern change or a color difference (δE) of more than 5.0.

(4) Chemical resistance evaluation

The color filter ink compositions of Examples 1 to 8 and Comparative Examples 1 to 2 were printed to be 1 to 2μm thick on a black matrix substrate and dried at 220 ⁰ C for 40 minutes with a forced convection drying oven, acquiring a pattern. This patterned substrate was soaked in a 5% sodium hydroxide aqueous solution, N-methylpyrrolidone (NMP), tetramethyl ammonium hydroxide (TMAH), and γ-butyrolactone (γ-GBL) for 30 to 40 minutes and dried, and its pattern change was photographed with an optical microscope. Then, the optical photograph was examined with the naked eye. In addition, the color difference (δE) was measured with a colorimeter. These chemical resistance measurement results are shown in the following Table 1.

Referring the following Table 1 , © denotes no pattern change and a color difference (δE) of less than 0.1 ; o denotes no pattern change and a color difference (δE) of less than 3.0; δ denotes a little pattern change and a color difference (δE) ranging from 3.0 to 5.0; and * denotes much pattern change and a color difference (δE) of more than 5.0.

(5) Film hardness evaluation

The color filter ink compositions of Examples 1 to 8 and Comparative Examples 1 to 2 were coated to be 1 to 2μm thick on a 0.7mm-thick degreased and washed glass substrate at 22O ⁰ C for 40 minutes in a convection oven. The prepared ink coating layers were evaluated regarding strength according to damage received when they were scratched with 1 H to 6H pencils (Staedtler Co.). The results are

shown in the following Table 1.

(6) Storage stability evaluation

The color filter ink compositions of Examples 1 to 8 and Comparative Examples 1 to 2 were stored at a constant temperature of 40 ⁰ C for a week to measure viscosity change. Herein, o denotes no viscosity change or a viscosity change of less than 0.2cPs, δ denotes a clear viscosity change ranging from 0.2 to 0.5 cPs, and x denotes a sharp viscosity change of more than O.δcPs.

(Table 1)

Referring to Table 1 , the ink compositions of Examples 1 to 8 turned out to have superbly higher chemical resistance, film hardness, and storage stability than those of Comparative Examples 1 and 2.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be

understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.