KR101111173B1 - Ink-jet ink composition for color filter and color filter comprising the same - Google Patents

Abstract

The present invention relates to an inkjet ink composition for a photocurable color filter that does not include a polymer resin, and a color filter including the same. A low viscosity ink including a hyperbranched acrylate, a polyfunctional monomer, a photopolymerization initiator, a dispersant, and an organic solvent. It relates to a composition.

The inkjet composition for a photocurable color filter of the present invention exhibits low thermal contraction rate, high film hardness, and excellent jetting characteristics when printing piezoelectric elements without using a polymer polymer conventionally used.

Inkjet Printing, Color Filters, Ink Compositions, Hyperbranched Acrylate

Description

Ink-jet ink composition for color filters and color filter comprising the same {INK-JET INK COMPOSITION FOR COLOR FILTER AND COLOR FILTER COMPRISING THE SAME}

The present invention relates to an inkjet ink composition for a photocurable color filter and a color filter comprising the same. More specifically, the present invention satisfies physical properties such as low thin film shrinkage, high film hardness, and the like, and does not use a conventional polymer, and satisfies low viscosity properties suitable for use in piezoelectric inkjet printing processes. It relates to an inkjet ink composition for photocurable color filters.

Color filters used in liquid crystal displays (LCDs) are components that implement various colors in liquid crystal displays. The main components of the color filter are the color layer representing color, the black matrix formed using chromium (Cr) or black resin to increase the contrast ratio, and the transparent ITO (Indium-) to drive the liquid crystal. Tin Oxide) layer.

The most widely used method for the production of color filters used in liquid crystal displays is the pigment dispersion method. In general, a pigment dispersion method forms a black matrix on a glass substrate, and then forms color pigments in the order of red, green, and blue in a photolithography process, and then forms an ITO layer on the color layer by sputtering. As an example of such a pigment dispersion method, Korean Patent Application No. 1999-0003779 discloses a manufacturing method using a pigment dispersion method. In this method, a photosensitive black matrix material is coated onto the entire surface using a spin or slit coater, and then Curing a specific pattern using a mask and then developing the exposed part to form a pattern, and dyeing the inside of the pattern using red, green, and blue photosensitive materials, respectively. However, this method has many problems such as complicated pixel pattern formation step and high cost.

Recently, liquid crystal display panels have been enlarged, demand for high speed and mass production of liquid crystal display devices has increased, and one of the newly developed color filter production technologies is ink jet printing. As an example of such an inkjet printing method, Korean Patent Application No. 2000-0022097 discloses a manufacturing process for forming a colored layer of a color filter by an inkjet system. In this process, the number of processes for manufacturing color filters can be significantly reduced, and the position of the resin discharged through the inkjet printer can be adjusted, and eventually, the material consumed, such as waste, can be significantly reduced, thereby reducing manufacturing costs. effective. However, color filter manufacturing using the inkjet printing method also has a variety of problems, one of which is the viscosity control of the ink. When inkjet printing, the proper viscosity of the ink is known to be 20 cP or less. In practice, the ink may have a stable jetting property when it is about 10 to 15 cP. When using a high viscosity polymer binder as in the conventional ink manufacturing method, in order to lower the viscosity of the ink to 10 to 15 cP, there is no choice but to use too much organic solvent. However, when the organic solvent is used too much, the dependence on the physical properties of the solvent, in particular, the vapor pressure is excessively increased, and the thickness of the colored portion of the color filter must be increased in consideration of evaporation of the organic solvent. Since the amount of ink drop of the inkjet printer head is fixed (10 to 35pL) at present, raising the thickness even a little thick in the inkjet color filter process requiring a constant volume causes a problem of lowering productivity.

Accordingly, an object of the present invention is to use a polymer polymer by compensating for a thermal defect that may occur without using a polymer polymer, while having a low viscosity suitable for use in an inkjet printing process by using only a small amount of organic solvent without using a polymer polymer. It is to provide an inkjet ink composition for a photocurable color filter having better thermal stability and film surface hardness than that used.

Another object of the present invention is to provide a color filter prepared from the ink composition prepared above.

In order to achieve the above object, the present invention comprises 10 to 50 parts by weight of hyperbranched acrylate, 10 to 50 parts by weight of a multifunctional monomer, 0.1 to 5 parts by weight of a photoinitiator, 10 to 50 parts by weight of a pigment and an organic solvent. Provided are inkjet ink compositions for photocurable color filters.

The present invention can improve the uniformity of the color filter by adding a lower viscosity of the low viscosity capable of inkjet printing and adding an organic solvent by using a low viscosity hyperbranched acrylate without using a high viscosity polymer polymer conventionally used. The combination of hyperbranched acrylates with many functional groups and polyfunctional monomers with high glass transition temperature (> 250 ^o C) improves the crosslinking density, resulting in better thermal stability and membrane performance compared to systems using polymers. Surface hardness. In addition, since the polymer does not enter the investment in the polymerization equipment does not have to be made, it may be a factor of cost reduction.

Hereinafter, the present invention will be described in detail.

The present invention provides an inkjet ink composition for a photocurable color filter comprising a hyperbranched acrylate, a polyfunctional monomer, a photopolymerization initiator, a pigment, and an organic solvent, and a color filter for a liquid crystal display device including the same.

The characteristic of hyperbranched acrylate is that it has a lower viscosity than the polymer having the same molecular weight even though it has a molecular weight similar to that of the existing linear polymer, and according to the purpose, there are five limitations of the polyfunctional monomer used in the existing. Since it is possible to control to have more acrylate groups than 6 acrylate groups in the controllable viscosity can be at the same time higher crosslinking density when using a photopolymerization initiator. The molecular weight of the hyperbranched acrylate used in the present invention is preferably a weight average molecular weight of 900 to 2,000, when the weight average molecular weight exceeds 2,000, there is a problem that the heat resistance and surface hardness is lowered due to lack of compatibility with other components There may be, if the weight average molecular weight is less than 900, there may be a problem that the hardened film is difficult to obtain a sufficient curing density and the heat resistance is lowered. The molecular weight of the hyperbranched acrylate used in the present invention is more preferably a weight average molecular weight of 1,000 to 2,000. The viscosity of the hyperbranched acrylate used in the present invention is preferably 900 cP or less, but if the viscosity exceeds 900 cP, the viscosity of the ink may increase and there may be a problem of nozzle clogging. The viscosity of the hyperbranched acrylate used in the present invention is more preferably 35 cP to 820 cP.

More preferably, the hyperbranched acrylate of the present invention has the structure of Formula 1 below.

In the above formula,

X is a central carbon substitutable for hydrogen or an alkyl group of C ₁ -C ₆ ;

R ₁ is a C ₁ -C ₆ alkyl group substituted or unsubstituted with an alkyl group;

R ₂ is a straight or branched alkyl group;

R ₃ is hydrogen or an acrylic group;

n = 1-3 and m = 3-6.

In the above formula, preferably, R ₁ may be a methyl group, ethyl group, propyl group or isopropyl group, butyl group, phenyl group, alkenyl group or cycloalkyl group, R ₂ is a C ₁ -C ₆ straight or branched alkyl group Can be used.

The number of acrylic groups can be controlled through reaction control. Hyperbranched acrylates are prepared according to the divergent method of sequentially synthesizing by synthesizing from a core nucleus molecule, as known in the art, and the convergent method of first forming an external nucleus and finally conjugating it to the central nucleus. Is possible. The production method used in the present invention is synthesized sequentially from the core by the divergent method.

In the present invention, the hyperbranched acrylate is used in 5 to 50 parts by weight, when present in excess of 50 parts by weight, the unreacted acrylic group is easily present in a large amount inside the protective film, there may be a problem that the properties of the cured film is unstable or adhesion is reduced, If it is less than 5 parts by weight, there may be a problem that it is difficult to obtain a cured film having a sufficiently high crosslink density. In the present invention, the hyperbranched acrylate is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight. The central component of the hyperbranched acrylate is not critical in the present invention, but is preferably a branched structure in which acrylate, which is a structure suitable for photopolymerization, is distributed on the surface.

A polyfunctional monomer (also called a photopolymerizable compound) refers to a compound that can be polymerized by a photopolymerization initiator that generates radicals through light irradiation such as UV, and most of the compounds having an acrylate group belong to this. In the present invention, a polyfunctional monomer having a glass transition temperature (Tg) of 250 ° C. or more is used. When the glass transition temperature is less than 250 ° C., the deterioration of the post-curing process of 230 to 250 ° C. occurs well, There is a problem that the shrinkage of the cured film is increased. In the present invention, the glass transition temperature of the multifunctional monomer is preferably 250 ° C to 300 ° C, more preferably 250 ° C to 280 ° C. Various polyfunctional monomers are known in the art and include, for example, tetramethylolmethane triacrylate, trimethylolpropane triacrylate, tris [2- (acryloyloxy)] isocyanate Latex, trimethylol propane tris [2- (acryloyloxy) ethyl] ether, and the like.

When the glass transition temperature of the polyfunctional monomer is high, the heat shrinkage rate is improved. In the conventionally used dipentaerythritol hexaacrylate having a low glass transition temperature, the number of functional groups reaches 5.5, but the heat shrinkage rate is 15 to 20. On the other hand, when the number of functional groups is 3 and tetramethylolmethane triacrylate having a high glass transition temperature is used, the heat shrinkage is only about 1 to 3%.

In the present invention, 10 to 50 parts by weight of the multifunctional monomer is used, but when the amount exceeds 50 parts by weight, there is a problem that the adhesion of the protective film obtained is lowered, when less than 10 parts by weight there is a problem that it is difficult to obtain a cured film with a sufficient curing density. In the present invention, the multifunctional monomer is preferably 10 to 40 parts by weight, more preferably 10 to 30 parts by weight.

A photoinitiator is what produces | generates a radical by irradiation of UV, Generally it can be divided into acetophenone type, a benzoin type, a benzophenone type, thioxanthone type, and a triazine type photoinitiator.

Examples of benzoin-based photopolymerization initiators include benzoin, benzoin methyl ether, benzoin isobutyl ether, and the like.

Examples of benzophenone-based photoinitiators include benzophenone, methyl o -benzoyl benzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 2,4,6-trimethylbenzophenone, and the like.

Examples of thioxanthone photopolymerization initiators include 2-isopropyl thioxanthone, 4-isopropyl thioxanthone, 2,4-diethyl thioxanthone, 2,4-dichlorothioxanthone, and the like.

Examples of triazine photoinitiators include 2,4-bis (trichloromethyl) -6- (4-methoxyphenyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (4-metholcinnaphthyl) -1,3,5-triazine, 2,4-bis (trichloromethyl) -6- (2- (5-methylfuran-2-yl) ethenyl) -1, 3,5-triazine, 2, 4-bis (trichloromethyl) -6- (2- (furan-2-yl) ethenyl) -1,3,5-triazine and the like.

In the present invention, the photopolymerization initiator is used in 0.1 to 5 parts by weight, if more than 5 parts by weight, the characteristics of the color filter is unstable and poor adhesion as well as long-term storage stability is lowered, if less than 0.1 parts by weight is sufficiently high There is a problem that it is difficult to obtain a crosslinking density. In the present invention, the photopolymerization initiator is preferably used 0.1 to 2 parts by weight.

Pigments can be broadly classified into organic and inorganic pigments and are well known in the art.

In the case of organic pigments, the compounds are classified into pigment groups according to the Color Index (CI). Specific examples thereof include Pigment Yellow No. 1, Pigment Yellow No. 12, Pigment Yellow No. 13, Pigment Yellow No. 14, Pig Pigment Yellow No. 15, Pigment Yellow No. 16, Pigment Yellow No. 17, Pigment Yellow No. 20, Pigment Yellow No. 24, Pigment Yellow No. 31, Pigment Yellow No. 53, Pigment Yellow No. 83, Pigment Yellow No. 86, Pigment Yellow No. 93, Pigment Yellow No. 94, Pigment Yellow No. 109, Pigment Yellow No. 110, Pigment Yellow No. 117, Pigment Yellow No. 125, Pigment Yellow No. 128, Pigment Yellow No. 137 Pigment Yellow No. 138, Pigment Yellow No. 139, Pigment Yellow No. 147, Pigment Yellow No. 148, Pigment Yellow No. 150, Pigment Yellow No. 153, Pigment Yellow No. 154, Pigment Pigment Yellow No. 166, Pigment Yellow No. 173, Pigment Orange No. 13, Pigment Orange No. 31, Pigment Orange No. 36, Pigment Orange No. 38, Pigment Orange No. 40, Pigment Orange No. 42, Pigment Orange No. 43, Pigment Orange No. 51, Pigment Orange No. 55, Pigment Orange No. 73, Pigment Red No. 9, Pigment Red No. 97, Pigment Red No. 105, Pigment Red No. 176, Pigment Red No. 177 Pigment Red No. 180, Pigment Red No. 196, Pigment Red No. 215, Pigment Red No. 216, Pigment Red No. 224, Pigment Red No. 242, Pigment Red No. 254, Pigment Red No. 264, Pig Pigment Red 265, Pigment Blue 15, Pigment Blue 15: 3, Pigment Blue 15: 4, Pigment Blue 15: 6, Pigment Blue 60, Pigment Brown 23, Pigment Brown No. 25, Pigment Green No. 7, and Pigment Green 36 And the like.

Examples of inorganic pigments include titanium oxide, barium sulfate, calcium carbonate, zinc oxide, lead sulfate, yellow lead, zinc yellow, red iron (III) oxide, cadmium red, ultramarine blue, prussian blue, chromium oxide green and cobalt green, etc. There is this.

These pigments can be used individually or in mixture, respectively.

If necessary, these pigments can be subjected to surface treatment such as acidic, basic treatment, graft treatment and washing treatment. The pigment according to the present invention may be mixed with a dispersant and a solvent to form a pigment dispersion in order to disperse stability. The solids of such pigment dispersions consist of pigments and dispersants, and the amount of solids used comprises 15 to 20% by weight relative to 100% by weight of the total pigment dispersion . In the present invention, 10 to 50 parts by weight of the pigment may be used when there is a problem that the physical properties of the color filter is lowered if it exceeds 50 parts by weight, less than 10 parts by weight may have a problem that the desired color and color concentration does not appear well. . In the present invention, the pigment is preferably 10 to 30 parts by weight.

The organic solvent used in the present invention is used to impart dispersing and jetting properties, for example n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol n-butyl ether acetate, diethylene glycol dimethyl Ether, dipropylene glycol monomethyl ether acetate, diethylene glycol methyl ethyl ether, diethylene glycol ethyl ether acetate, dipropylene glycol n-butyl ether, methyl ethyl carbitol, tripropylene glycol n-propyl ether, tripropylene glycol methyl ether Propylene glycol methyl ether acetate, propylene glycol diacetate, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, cyclohexanone, 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, etc. There is this.

As the solvent used in the present invention, it is preferable to use a solvent having a high boiling point (200 ° C. or more) in order to prevent the nozzle from clogging due to evaporation of the solvent during ink jetting. In the present invention, 30 to 80 parts by weight of the solvent is used. If it exceeds 80 parts by weight, there may be a problem that the residual film ratio is lowered after pixel formation. In the present invention, the solvent is preferably used 50 to 70 parts by weight.

In the present invention, a dispersant may optionally be used, and one of the dispersants usable may include a surfactant. The surfactant may be a silicone-based surfactant and a fluorine-based surfactant, and examples of the silicone-based surfactant include BYK-300, copper 310, copper 320, copper 330, copper 333, copper 370, copper 371, and TEGO's Glide 400 and copper 410. , Wet270, and the like, and examples of the fluorine-based surfactant include BYK-340, BM-1000, 1100, Surflon S112, S131, and S382. One or more of the surfactants having an acrylate group reactive to the exposure process, such as BYKUV-3700 and 33710 may be included. In the present invention, 0.1 to 3 parts by weight of the surfactant is used, if more than 3 parts by weight may have a stability problem, less than 0.1 parts by weight may have a problem in dispersibility. In the present invention, the surfactant is preferably used 0.1 to 1 parts by weight.

In the present invention, other additives may optionally be added to improve the properties of the composition.

As other additives, an adhesion aid, an antioxidant, an ultraviolet absorber, an anti-agglomerating agent, etc. may be added to improve adhesion between the substrate and the film to be applied.

Examples of the adhesion aid may be a functional silane coupling agent, specifically trimethoxysilylbenzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanate Propyltriethoxysilane and the like.

Examples of antioxidants include 2,2-thiobis (4-methyl-6-t-butylphenol), 2,6-di-t-butylphenol and the like.

Examples of ultraviolet absorbers include alkoxybenzophenone, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, and the like.

Examples of anti-agglomerating agents include sodium polyacrylates and the like.

Such additives, if used, may be used up to 1 part by weight.

Hereinafter, the present invention will be described in detail by way of examples. However, the embodiments are only for illustrating the present invention and the scope of the present invention is not limited thereto. Examples 1 to 3

Example  One

7 15 parts by weight of a functional hyperbranched acrylate (Miwon Corporation, sp1114), 15 parts by weight of tetramethylolmethane triacrylate as a polyfunctional monomer, C.I. Pigment Red 254 10 parts by weight of pigment, Igacure 369, 907 (Ciba) 1 part by weight of a photopolymerization initiator mixed with an organic solvent and 50 parts by weight of methyl ethyl carbitol by mixing an organic solvent for a color filter of 14cP Inkjet ink compositions were prepared.

Example  2

7 15 parts by weight of a functional hyperbranched acrylate (Miwon Corporation, sp1114), 15 parts by weight of tetramethylolmethane triacrylate as a polyfunctional monomer, C.I. Pigment Green 7 10 parts by weight of pigment, Igacure 369, 907 (Ciba) 1 part by weight of a photopolymerization initiator mixed with 1 part by weight and 50 parts by weight of methyl ethyl carbitol mixed with an organic solvent for a solution viscosity of 14cP Inkjet ink compositions were prepared.

Example  3

7 15 parts by weight of a functional hyperbranched acrylate (Miwon Corporation, sp1114), 15 parts by weight of tetramethylolmethane triacrylate as a polyfunctional monomer, C.I. Pigment Blue 15: 3 10 parts by weight of pigment, Igacure 369, 907 (Ciba) in a ratio of 1: 1 by weight of a photoinitiator mixed with an organic solvent of 50 parts by weight of methyl ethyl carbitol, a solution viscosity of 14 cP A filter inkjet ink composition was prepared.

Comparative example  One

Glycidyl methacrylate: methyl methacrylate and methacrylic acid were polymerized at 30:50:20 for 240 minutes in a methylethylcarbitol solvent at a temperature of 65 DEG C, and the solid content was 30 parts by weight, and the weight average molecular weight was 12,000. The coalescence was prepared.

15 parts by weight of the copolymer, 15 parts by weight of dipentaerythritol hexaacrylate as a polyfunctional monomer, C.I. Pigment Blue 15: 3 Pigment 10 parts by weight, 1 part by weight of a photopolymerization initiator mixed with Igacure 369, 907 and 70 parts by weight of methyl ethyl carbitol are mixed with an organic solvent, the inkjet ink for color filters having a solution viscosity of 14 cP The composition was prepared. In this case, the amount of solvent had to be increased very much to reach the level of proper viscosity.

Experimental Example  One: Heat shrinkage  And uniformity measurements

The ink of Examples 1 to 3 and Comparative Example 1 was coated to a thickness of 1.5 μm, followed by prebake for 2 minutes on a 90 ° C. hotplate, and immediately after exposure using a UV lamp at 230 ° C. Post bake was carried out in the oven for 1 hour. After further heat treatment at 250 ° C. for 1 hour, the heat shrinkage was measured by measuring the thickness before and after the heat treatment, and the uniformity in the panel was evaluated with the final thickness. Thermal contraction rate and uniformity were calculated by the following formula.

Thermal Shrinkage (%) = (Thickness average after baking at 250 ° C) / (Thickness average after baking at 230 ° C) x 100

Uniformity (%) = [1- (Max Thickness-Min Thickness) / (Max Thickness + Min Thickness)] x 100

The measurement results are shown in Table 1 below.

As can be seen in Table 1, the ink prepared through Examples 1 to 3 showed a relatively low heat shrinkage rate, and uniformity showed a value of 95% or more, showing a high level of uniformity.

Experimental Example  2: surface hardness measurement

Inks of Examples 1 to 3 and Comparative Example 1 were each coated with a thickness of 1.5 μm, and then surface hardness was measured using a pencil hardness tester (JIS K5600).

The measurement results are shown in Table 2 below.

As can be seen from Table 2, it was confirmed that the surface hardness of the final cured product of the inks of Examples 1 to 3 was very excellent compared to the hardness of the final cured product of the ink of Comparative Example 1. This is believed to be due to the increase in crosslinking density due to the high functionality of the hyperbranched acrylates.

Experimental Example  3: Jetting  Experiment

The ink compositions of Examples 1 to 3 and Comparative Example 1 were first jetted using an inkjet printer, and then waited for 5 minutes, and then jetted again. The head of the inkjet printer used SE-128DPN (Spectra), and the printability and nozzle clogging after printing were examined.

    ◎: When jetting is performed well without clogging the nozzle

    ○: When the nozzle is clogged well after jetting

    X: No jetting or nozzle is completely clogged

As can be seen in Table 3, the ink prepared in Example 1 and Example 2 was found to print well without nozzle clogging up to 10 times continuously. However, in Example 3 and Comparative Example 1, the nozzles were partially blocked after 7 times and 3 times, respectively, during jetting.

Claims (9)

10 to 50 parts by weight of the hyperbranched acrylate having the structure of Formula 1, 5 to 50 parts by weight of the polyfunctional monomer having a glass transition temperature (Tg) of 250 ° C. or more, 0.1 to 5 parts by weight of the photopolymerization initiator, and 10 to 50 parts by weight of the pigment And an inkjet ink composition for a photocurable color filter comprising an organic solvent: [Formula 1]

In the above formula, X is a central carbon substitutable for hydrogen or an alkyl group of C ₁ -C ₆ ; R ₁ is a C ₁ -C ₆ alkyl group substituted or unsubstituted with an alkyl group; R ₂ is a straight or branched alkyl group; R ₃ is hydrogen or an acrylic group; n = 1-3 and m = 3-6. delete The ink composition of claim 1, wherein the hyperbranched acrylate has a weight average molecular weight of 900 to 2,000 and a viscosity of 900 cP or less. delete The method of claim 1, wherein the multifunctional monomer is tetramethylolmethane triacrylate, trimethylolpropane triacrylate, tris [2- (acryloyloxy)] isocyanurate and trimethylol propane tris [2- ( Acryloyloxy) ethyl] ether ink composition, characterized in that at least one member selected from. The ink composition of claim 1, wherein the pigment is an organic pigment or an inorganic pigment. The ink composition of claim 1, further comprising 0.1 to 3 parts by weight of a dispersant based on 100 parts by weight of the ink composition. The ink composition of claim 1, wherein the ink composition has a viscosity of 10 to 15 cP. The color filter formed by the ink composition of any one of Claims 1, 3, and 5-8.