WO2010151078A2

WO2010151078A2 - Photopolymerizable resin composition

Info

Publication number: WO2010151078A2
Application number: PCT/KR2010/004146
Authority: WO
Inventors: Jae Gook Han; Young Sung Suh; Kyung Keun Yoon
Original assignee: Kolon Industries, Inc.
Priority date: 2009-06-26
Filing date: 2010-06-25
Publication date: 2010-12-29
Also published as: JP2012531619A; KR20110000042A; WO2010151078A3; CN102460300A; TW201100959A; KR101368539B1; CN102460300B; WO2010151078A9

Abstract

This invention relates to a photopolymerizable resin composition which exhibits appropriate optical density and adequate hydrophobicity upon formation of a film and is thus useful in preventing color mixing or position deviation of color ink upon injection of color ink through a jetting method using an ink-jet print into regions defined by barrier ribs (a light shielding film) formed using the photopolymerizable resin composition.

Description

PHOTOPOLYMERIZABLE RESIN COMPOSITION

The present invention relates to a photopolymerizable resin composition adapted to form a light shielding film of an image display device, such as a liquid crystal display (LCD).

LCDs show an image using optical anisotropy and birefringence of liquid crystal molecules. As such, when an electric field is applied, the alignment of liquid crystals is changed, so that transparency varies depending on the changing alignment of the liquid crystals.

Generally, LCDs are devices in which two substrates with electric field production electrodes respectively formed thereon are disposed such that the two electrodes face each other, a liquid crystal material is injected between the two substrates, and voltage is then applied between the two electrodes to produce an electric field which moves the liquid crystal molecules and varying the transmittance of light, thereby displaying an image.

For example, thin film transistor (TFT)-LCDs which are widely useful include a lower substrate, known as an array substrate, on which a TFT and a pixel electrode are disposed; an upper substrate, known as a color filter substrate, which includes a plastic or glass substrate, a black matrix and red, green and blue color layers repetitively formed on the plastic or glass substrate, an overcoat layer formed to a thickness of 1 ~ 3 ㎛ on the black matrix and color layers using polyimide, polyacrylate or polyurethane so as to protect a color filer and to maintain surface flatness, and an indium tin oxide (ITO) transparent conductive layer which is formed on the overcoat layer and to which voltage is applied to drive liquid crystals; and liquid crystals charged between the upper and lower substrates, and polarizers attached to both surfaces of the two substrates so as to linearly polarize visible light (natural light). In the TFT-LCDs, external peripheral circuits apply voltage to the gate of the TFT constituting pixels to cause the TFT to turn on so that liquid crystals are put in a state to which zero phase voltage can be input, after which zero phase voltage is applied to the liquid crystals so that image information is stored in the liquid crystals, after which the TFT turns off so that electric charges stored in a liquid crystal capacitor and a storage capacitor are preserved, thus displaying an image for a predetermined period of time. Light is diffracted when it passes through liquid crystals whose alignment has been changed by applying a voltage to them. This light passes through the polarizers, thereby obtaining a desired image.

Recent attempts are being made to form the color filter of the LCD on the lower substrate, namely, the array substrate, but not on the upper substrate, namely, the color filter substrate, in order to increase an aperture ratio and reduce the manufacturing cost while simplifying the manufacturing process.

Despite such structural changes, methods of manufacturing the color filter typically include dyeing, dispersion, electrodeposition, printing, jetting and so on. The technique for manufacturing the color filter using the jetting method using an ink-jet print is advantageous because the color filter manufacturing process may be simplified and the manufacturing cost may be reduced. However, it is very difficult for the color filters resulting from the jetting method using the ink-jet print to ensure uniformity in the display cells in the glass substrate. Poor uniformity of the color filter mainly results from different amounts of ink being discharged from nozzles of an ink-jet print head. As the amounts of ink discharged from respective nozzles of the ink-jet print head are different, the amounts of color ink charged in respective pixel regions are also different, undesirably resulting in generated stains. Furthermore, in the case where color ink is charged into internal spaces corresponding to pixel regions defined by a light shielding pattern, namely, a black matrix, repulsive force between the light shielding pattern and the color ink and surface tension of the color ink cause the surface of the color ink to swell upwards, so that the color ink assumes the form of a dome. Because the color ink has assumed a dome form in the internal spaces, the thickness of the color filer formed at the center of the pixel region is different from the thickness of the color filter formed at the edge of the pixel region, undesirably causing color differences. Hence, such poor uniformity of the color filter ultimately deteriorates the display quality.

Accordingly, the present invention is intended to provide a photopolymerizable resin composition which exhibits appropriate optical density and adequate hydrophobicity upon formation of a cured film.

In particular, the present invention is intended to provide a photopolymerizable resin composition which is useful as a barrier rib material during the formation of a color layer by virtue of a jetting method using an ink-jet print.

An aspect of the present invention provides a photopolymerizable resin composition, which includes an alkali soluble acrylic binder resin and a cardo based binder resin, and which satisfies all of the first to third conditions as below upon formation of a resin cured film: a first condition is that an optical density per unit thickness of 2.0 ㎛ is 2.0 or more; a second condition is that a contact angle to water is 85 or more; and a third condition is that a contact angle to 2-ethoxyethanol is 35°or more.

In this aspect, the contact angle to water may be 85 ~ 110 upon formation of the resin cured film.

In this aspect, the contact angle to 2-ethoxyethanol may be 35 ~ 50 upon formation of the resin cured film.

In this aspect, the photopolymerizable resin composition may include a colorant containing a pigment mixture composed of at least two pigment components able to show a substantial black color upon mixing. As such, the pigment mixture may essentially include a red pigment and a blue pigment, and may further include one or more selected from among a yellow pigment, a green pigment and a violet pigment, and the pigment mixture may include 10 ~ 50 wt% of the red pigment, 10 ~ 50 wt% of the blue pigment, 1 ~ 20 wt% of the yellow pigment and 1 ~ 20 wt% of the green pigment, which are expressed as solid content, based on the total weight of the colorant. Furthermore, the pigment mixture may include 1 ~ 20 wt% of the violet pigment, which is expressed as solid content, based on the total weight of the colorant.

In the photopolymerizable resin composition, the pigment mixture may include a black pigment. As such, the black pigment may be used in an amount of 10 wt% or less, which is expressed as solid content, based on the total weight of the colorant.

In the photopolymerizable resin composition, the colorant may be used in an amount of 20 ~ 80 wt% based on the total weight of the photopolymerizable resin composition.

In this aspect, the photopolymerizable resin composition may include a multifunctional monomer having an ethylenically unsaturated double bond, a photoinitiator, and a solvent.

In this aspect, the alkali soluble acrylic binder resin may include an epoxy group.

In the photopolymerizable resin composition, the alkali soluble acrylic binder resin may include a fluorine group, and in particular, the amount of the fluorine of the alkali soluble acrylic binder resin may be 5 ~ 50 wt%.

In the photopolymerizable resin composition, the pigment mixture may be provided in the form of a pigment dispersion solution in which respective pigments are dispersed in a solvent, and the pigment dispersion solution may contain at least one pigment dispersant selected from among acrylate based pigment dispersants, the amount of the pigment dispersant being 3 ~ 20 wt% based on the total weight of the pigment dispersion solution.

In the photopolymerizable resin composition, the pigment dispersion solution may include a fluorine group-containing acrylic binder resin.

In the photopolymerizable resin composition, the cardo based binder resin may contain a fluorine group.

In this aspect, the photopolymerizable resin composition may include a fluorine group-containing epoxy monomer.

Also in this aspect, the photopolymerizable resin composition may include a fluorine group-containing siloxane based monomer.

In this aspect, the fluorine may be contained in an amount of 5 ~ 50 wt% per a cured film weight of 1 g upon formation of the cured film.

Another aspect of the present invention provides a color filter substrate, including a black matrix formed by photolithography using the above photopolymerizable resin composition.

A further aspect of the present invention provides a thin film transistor substrate, including a black matrix formed by photolithography using the above photopolymerizable resin composition.

Still another aspect of the present invention provides an image display device, including the above color filter substrate as an upper substrate.

Yet another aspect of the present invention provides an image display device, including the above thin film transistor substrate as a lower substrate.

The photopolymerizable resin composition according to the present invention may exhibit appropriate optical density and adequate hydrophobicity upon formation of a cured film. Thus, in the case where a light shielding pattern is formed using such a composition, color ink can be injected into regions defined by the light shielding pattern by virtue of a jetting method using an ink jet print, thus solving problems such as color mixing due to the color ink overflowing the light shielding pattern or such as position deviation of the color ink. Thereby, it is easy to form color layers thanks to the jetting method using an ink jet print, consequently reducing display defects.

A detailed description will be given of the present invention.

In the fabrication of a color filter, a jetting method using an ink-jet print includes forming a light shielding pattern from a photopolymerizable resin composition having light shielding properties by means of photolithography, and then jetting color ink (red, green, blue colors) into regions corresponding to respective pixels defined by the light shielding pattern, thus forming color layers.

This jetting method for forming the color layers may simplify the process and may reduce the cost compared to when using photolithography to form red, green and blue color layers. Also, this jetting method may increase the range of reproducible colors depending on the amount of color ink injected, thus exhibiting superior color reproducibility and making the thickness and composition of the pattern uniform. Also, this jetting method facilitates the formation of a microcircuit pattern and is suitable for use in flexible displays. Also, this jetting method may decrease the consumption of photoresist, solvent and energy and is thus environmentally friendly.

However, the jetting method using an ink-jet print requires the accuracy and capabilities of ink-jet printing and materials suitable for ink-jet printing.

Thus, the present invention is directed to a photopolymerizable resin composition able to form a light shielding pattern useful when forming color layers by virtue of such a jetting method using an ink jet print.

From this point of view, a photopolymerizable resin composition according to an embodiment of the present invention includes an alkali soluble acrylic binder resin and a cardo based binder resin, and satisfies all of the following first to third conditions upon formation of a resin cured film.

The first condition is that an optical density (OD) per unit thickness of 2.0 ㎛ is 2.0 or more.

The second condition is that a contact angle to water is 85°or more.

The third condition is that a contact angle to 2-ethoxyethanol is 35° or more.

If the optical density (OD) per unit thickness of 2 ㎛ is less than 2.0, it is difficult to exhibit appropriate light shielding effects despite the thickness of a cured film being slightly increased. Furthermore, in the case where the resulting film acts as a light shielding film, it does not sufficiently manifest light shielding properties, so that light may pass through a region out of a transparent pixel electrode, making it impossible to shield such uncontrolled light.

Also upon formation of the resin cured film, if the contact angle to water is less than 85°problems related to ink jetting, such as the ink overflowing the pixel region or different amounts of the color ink being charged, may occur.

Also, if the contact angle to 2-ethoxyethanol is less than 40° problems related to ink jetting, such as the ink overflowing the pixel region or different amounts of the color ink being charged, may occur.

Because color ink is injected into a light shielding pattern which is typically formed on glass, in order to prevent color mixing or position deviation after injection of the color ink, the surface tension of the glass should be larger than or at least equal to the surface tension of the color ink. In the case of the light shielding pattern, its surface tension should be smaller than the surface tension of the color ink.

For this reason, the photopolymerizable resin composition according to the embodiment of the present invention may exhibit a contact angle to water ranging from 85°to 110°and/or a contact angle to 2-ethoxyethanol ranging from 35°to 50°upon formation of the resin cured film.

In order to satisfy light shielding properties and hydrophobicity using the photopolymerizable resin composition, various methods are devised and include, but are not limited to, introducing a functional group for imparting hydrophobicity into a binder resin, the addition of a monomer having a functional group for imparting hydrophobicity as an additional monomer, the dispersion of a fluorine group-containing resin in a pigment, etc.

The photopolymerizable resin composition according to the embodiment of the present invention may include a pigment mixture composed of at least two pigment components able to show a substantial black color when mixed, among colorants which show light shielding properties.

A typical photopolymerizable resin composition for exhibiting light shielding properties includes a black pigment, and an example of the black pigment may include carbon black or titanium black. However, in the case where light shielding properties are exhibited using such a black pigment, a black pigment such as carbon black or titanium black may act as an ionic impurity, and thus the resulting cured film has poor compression properties.

For this reason, the photopolymerizable resin composition according to the embodiment of the present invention is designed to exhibit a substantial black color using the pigment mixture. As used herein, the term substantial black color is understood to refer to a black color which is black enough to absorb light of the entire visible light range (380 nm ~ 780 nm) based on the UV spectrum.

The pigment mixture may be obtained by mixing pigment dispersion solutions in which pigment components are dispersed in a solvent.

Upon mixing pigment components, organic pigments may be used in consideration of light transmittance and a dielectric constant. Specifically, a red pigment and a blue pigment are essentially added, and also a yellow pigment or a green pigment may be further added. In addition, a violet pigment may be further mixed in.

Examples of the pigments include, but are not limited to, red pigments identified by Color Index (C.I.) Nos. 3, 23, 97, 108, 122, 139, 149, 166, 168, 175, 177, 180, 185, 190, 202, 214, 215, 220, 224, 230, 235, 242, 254, 255, 260, 262, 264 and 272, yellow pigments identified by C.I. Nos. 13, 35, 53, 83, 93, 110, 120, 138, 139, 150, 154, 175, 180, 181, 185, 194 and 213, blue pigments identified by C.I. Nos. 15, 15:1, 15:3, 15:6, 36, 71 and 75, green pigments identified by C.I. Nos. 7 and 36, and violet pigments identified by C.I. Nos. 15, 19, 23, 29, 32, and 37.

Also, a black pigment having high resistance may be further added, as necessary. An example of the black pigment includes, but is not limited to, carbon black or titanium black.

The pigment mixture may include 10 ~ 50 wt% of a red pigment, 10 ~ 50 wt% of a blue pigment, 1 ~ 20 wt% of a yellow pigment and 1 ~ 20 wt% of a green pigment, which are expressed as solid content, based on the total weight of the colorant. In addition, a violet pigment may be used in an amount of 1 ~ 20 wt%, which is expressed as solid content, based on the total weight of the colorant. Also, a black pigment may be used in an amount equal to or smaller than 10 wt%, which is expressed as solid content, based on the total weight of the colorant. Because most black pigments conduct electricity, problems of a dielectric constant being increased may occur and electrical properties of a cured film may deteriorate. Hence, in the case where a black pigment is included, one having high resistance is preferably selected, and the amount thereof may be set to 15 wt% or less, which is expressed as solid content, based on the total weight of the colorant.

The optical density and electrical resistance of a light shielding film formed from the photopolymerizable resin composition may vary depending on the degree of pigment dispersion. Thus, the colorant may include a pigment dispersant. Examples of the pigment dispersant include polymer dispersants such as modified polyurethane, modified polyacrylate, modified polyester and modified polyamide, and surfactants such as phosphoric acid ester, polyester and alkylamine. Among them, particularly useful is an acrylate based dispersant, specific examples of which include Disperbyk-2000, Disperbyk-2001, LP-N-21116, LP-N-21208, available from BYK chemie, EFKA-4300, EFKA-4330, EFKA-4340, EFKA-4400, EFKA-4401, EFKA-4402, EFKA-4046 and EFKA-4060 available from Ciba, and which is more favorable in terms of dispersion stability, optical density and electrical properties.

However, excessively adding the pigment dispersant may result in poor dispersion stability or degradation of a specific functional group thus deteriorating pattern stability. For this reason, the pigment dispersant may be used in an amount of 3 ~ 20 wt% based on the total weight of the colorant in dispersion solution form, that is, the pigment dispersion solution.

The total amount of the colorant may be about 20 ~ 80 wt%, and preferably about 30 ~ 66 wt%, based on the total weight of the photopolymerizable resin composition. If the amount of pigment mixture is less than 20 wt%, the optical density of the formed light shielding film is low, undesirably resulting in insufficient light shielding properties. In contrast, if the amount thereof exceeds 80 wt%, the amount of the photopolymerizable resin component is reduced and curing properties become poor, undesirably resulting in developing properties being problematic and generating residue.

In addition, the photopolymerizable resin composition according to the embodiment of the present invention may include an alkali soluble binder resin, a photopolymerizable monomer having an ethylenically unsaturated group, a photoinitiator and a solvent. Specifically, the photopolymerizable resin composition according to the embodiment of the present invention may include, along with the above colorant, an alkali soluble acrylic binder resin, a cardo based binder resin, a multifunctional monomer having an ethylenically unsaturated double bond, a photoinitiator and a solvent.

The alkali soluble acrylic binder resin may include a copolymer resulting from copolymerization of an acid functional group-containing monomer and another monomer which is copolymerized with the above monomer. The strength of the film may be further enhanced when using copolymer resin rather than when using homopolymer resin. Alternatively, a polymer compound resulting from polymerization of the above copolymer and an epoxy group-containing ethylenically unsaturated compound may be utilized.

Specifically, the alkali soluble binder resin may include a copolymer resulting from copolymerization of an acid functional group-containing monomer and another monomer able to be copolymerized with the above monomer. In addition to the above copolymer, a polymer compound formed by bonding an epoxy group-containing ethylenically unsaturated compound to the above copolymer may be used together.

Examples of the acid functional group-containing monomer include, but are not limited to, (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monomethyl maleic acid, isoprene sulfonic acid, styrene sulfonic acid, and 5-norbornene-2-carboxylic acid, which may be used alone or in mixtures of two or more.

In particular, because a cured film should have high alkali resistance, an epoxy group-containing binder resin is preferably used. Hence, when an alkali soluble resin is prepared, it is preferred that an epoxy group-containing monomer is used along with the acid functional group-containing monomer.

Examples of the epoxy group-containing monomer include, but are not limited to, acrylic acid glycidyl, methacrylic acid glycidyl, a-ethylacrylic acid glycidyl, a-n-propylacrylic acid glycidyl, a-n-butylacrylic acid glycidyl, acrylic acid-3,4-epoxy butyl, methacrylic acid-3,4-epoxybutyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid-6,7-epoxyheptyl, a-ethylacrylic acid-6,7-epoxyheptyl, o-vinylbenzylglycidylether, m-vinylbenzylglycidylether, and p-vinylbenzylglycidylether.

Also, in order to exhibit hydrophobicity when forming a cured film from the photopolymerizable resin composition according to the present invention, the alkali soluble acrylic binder resin should contain a fluorine group. Thus, a fluorine group-containing monomer may be used together with the monomer in the preparation of acrylic binder resin.

The fluorine group-containing monomer is not particularly limited so long as it is able to be copolymerized with other monomers and has one carbon double bond. An example thereof includes CH₂=CHC(O)OCHCH₂(CF₂)xCF₃ (wherein x is an integer from 1 to 12).

The amount of the fluorine group-containing monomer may be adjusted depending on the amount of the fluorine group of the monomer. The amount of the fluorine of the alkali soluble acrylic binder may be adjusted to 5 ~ 50 wt% in terms of satisfying the contact angle to water and the contact angle to 2-ethoxyethanol and preventing developing properties, coatability and dispersion stability from deteriorating.

The alkali soluble acrylic binder resin is used in an amount of about 1 ~ 40 wt% and preferably about 20 ~ 30 wt% based on total solid weight of the photopolymerizable resin composition. However, in the case where the alkali soluble acrylic binder includes a fluorine group, when the amount thereof increases, hydrophobicity is increased but processability may deteriorate. Preferable is the use of an alkali soluble acrylic binder having a fluorine group in an amount of 5 ~ 50 wt% based on total solid weight of the photopolymerizable resin composition.

The alkali soluble acrylic binder resin thus obtained may be used as a binder resin and as well may be added in a small amount upon preparation of the above colorant thus exhibiting hydrophobicity.

If the acrylic binder resin having a fluorine group is added to the colorant, the amount thereof may be set to 1 ~ 30 wt% based on solid content in terms of pigment dispersion or hydrophobicity.

When the photopolymerizable resin composition is prepared from only the alkali soluble acrylic binder resin, a large amount of multifunctional monomer should be used to form a light shielding film having a thickness of 2.2㎛ or more, and thereby surface hardening rapidly occurs due to photocuring, undesirably resulting in wrinkles being generated upon thermal curing. For this reason, the photopolymerizable resin composition according to the embodiment of the present invention includes a cardo based compound as the binder resin. The cardo based compound is referred to as an acrylate based binder resin the main chain of which includes a fluorene group, and the structure thereof is not particularly limited.

This compound is exemplified by a compound represented by Formula 1 below.

Formula 1

wherein X is represented by

.

Also, Y may be a residue of acid anhydride selected from among maleic anhydride, succinic anhydride, cis-1,2,3,6-tetrahydrophthalic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, phthalic anhydride, itaconic anhydride, 1,2,4-benzenetricarboxylic anhydride, methyl-tetrahydrophthalic anhydride, citraconic anhydride, 2,3-dimethylmaleic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride, cis-5-norbonene-endo-2,3-dicarboxylic anhydride, and 1,8-naphthalic anhydride.

Also, Z may be a residue of acid dianhydride selected from among 1,2,4,5-bezenetetracarboxylic dianhydride, 4,4'-biphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, pyromelitic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,4,5-tetracarboxylic anhydride, methylnorbonene-2,3-dicarboxylic anhydride, 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]diphthalic anhydride, 4,4'-oxydiphthalic anhydride, and ethyleneglycol bis(anhydrotrimelitate).

According to an exemplary embodiment of the present invention, a functional group able to impart hydrophobicity may be introduced into such a cardo based compound. In particular, a fluorine group may be introduced as mentioned above.

In the course of the preparation of the cardo based compound, the introduction of a fluorine group and examples of a compound usable in the introduction of such a group are not limited. Specifically, there is a compound resulting from Reaction 1 below.

Reaction 1

Reaction 1 illustrates the introduction of the fluorine group to the cardo based compound, and is not construed to limit the cardo based compound having a fluorine group usable in the present invention.

The cardo based compound may be used in an amount of about 1 ~ 40 wt% and preferably about 20 ~ 30 wt% based on total solid weight of the photopolymerizable resin composition. When a fluorine group-containing compound is used as the cardo based compound, the amount thereof may be set to 5 ~ 10 wt% based on total solid weight of the photopolymerizable resin composition in consideration of hydrophobicity, developing properties, coatability and dispersion stability.

However, if the photopolymerizable resin composition is prepared from only the cardo based compound, the cardo based compound reacts with the multifunctional monomer having an ethylenically unsaturated double bond by being photocured upon formation of a cured film having a thickness of 2.2 ㎛ or more, and thus only surface hardening rapidly occurs, undesirably resulting in wrinkles because of the internal shrinkage which occurs upon thermal curing.

The photopolymerizable resin composition according to the embodiment of the present invention may include a multifunctional monomer having an ethylenically unsaturated double bond, which plays a role in forming a photoresist phase using light. This monomer may include one or more selected from among propyleneglycol methacrylate, dipentaerythritol hexaacrylate, dipentaerythritol acrylate, neopentylglycol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol acrylate, tetraethyleneglycol methacrylate, bis-phenoxy ethylalcohol diacrylate, trishydroxyethyl isocyanurate trimethacrylate, trimethylpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate and dipentaerythritol hexamethacrylate.

This monomer is used in an amount of 0.1 ~ 99 parts by weight based on 100 parts by weight of the compound of Formula 1, so that it may perform the radical reaction of a photoinitiator using UV light to form a cross-linkage thus forming a pattern and enhancing bondability of pigment and component particles to increase optical density.

In the embodiment of the present invention, a monomer for imparting hydrophobicity may be further added, and is selected so as to ensure hydrophobicity without deteriorating the coatability, adhesiveness and leveling properties of the photopolymerizable resin composition.

An example thereof includes a fluorine based epoxy compound represented by CH₂(O)CHCH₂(CF₂)_xCF₃ (wherein x is an integer from 1 to 12), a fluorine group-containing siloxane based compound, such as CF₃(CF₂)_ySi(OMe)₃ (wherein y is an integer from 1 to 12).

In the case where such a monomer is used as the additive, the amount thereof may vary in consideration of coatability, adhesiveness, leveling properties and hydrophobicity, and is preferably set to 1 ~ 12 wt% based on total solid content.

The photopolymerizable resin composition according to the embodiment of the present invention may include a photoinitiator, and examples of the photoinitiator include oxime ester compounds, such as 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), 1,2-octanedione-1[(4-phenylthio)phenyl]-2-benzoyl-oxime); ketones such as thioxanthone, 2,4-diethyl thioxanthone, thioxanthone-4-sulfonic acid, benzophenone, 4,4'-bis(diethylamino)benzophenone, acetophenone, p-dimethylaminoacetophenone, dimethoxyacetoxybenzophenone, 2,2'-dimethoxy-2-phenylacetophenone, p-methoxyacetophenone, 2-methyl[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2-benzyl-2-diethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, and 1-hydroxycyclohexylphenylketone; quinones such as anthraquinone and 1,4-naphthoquinone; halogen compounds such as 1,3,5-tris(trichloromethyl)-s-triazine, 1,3-bis(trichloromethyl)-5-(2-chlorophenyl)-s-triazine, 1,3-bis(trichlorophenyl)-s-triazine, phenacyl chloride, tribromomethyl phenylsulfone, and tris(trichloromethyl)-s-triazine; peroxides such as di-t-butyl peroxide; and acyl phosphine oxides such as 2,4,6-trimethyl benzoyl diphenyl phosphine oxide.

The photoinitiator may be used in an amount of 1 ~ 30 wt% based on the total amount of the resin composition.

The photopolymerizable resin composition according to the embodiment of the present invention includes a solvent, and examples of the solvent include propyleneglycolmethyletheracetate (PGMEA), propyleneglycolethyletheracetate, propyleneglycolmethylether, propyleneglycolpropylether, methylcellosolveacetate, ethylcellosolveacetate, diethylglycolmethylacetate, ethylethoxypropionate, methylethoxypropionate, butylacetate, ethylacetate, cyclohexanone, acetone, methylisobutylketone, dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidinone, dipropyleneglycolmethylether, toluene, methylcellosolve and ethylcellosolve.

The amount thereof may be about 20 ~ 60 wt% based on the total amount of the photopolymerizable resin composition.

In addition, a typical additive may be further included, as necessary.

The photopolymerizable resin composition may be prepared by mixing (a) a pigment mixture, (b) an alkali soluble acrylic binder resin, (c) a cardo based compound, (d) a multifunctional monomer having an ethylenically unsaturated double bond, (e) a photoinitiator and as necessary an organic additive and (f) a solvent using a stirrer, and filtering the resulting mixture using a 5 ㎛ membrane filter.

Such a photopolymerizable resin composition is applied on a glass substrate having a clear surface or a glass substrate having a transparent electrode layer (e.g. ITO or IZO deposited glass substrate) using a non-contact coater such as a spin coater (which is a rotary type) or a slit coater (which is a non-rotary type).

In the preparation and application, in order to enhance adhesiveness between the substrate and the photopolymerizable resin composition, a silane coupling agent may be blended with the resin composition or may be applied on the substrate.

Thereafter, the applied composition may be dried at 80 ~ 120℃, preferably 80 ~ 100℃ for 60 ~ 150 sec using a hot plate, may be allowed to stand at room temperature for a time period ranging from several hours to several days, or may be placed in a hot heater or an IR heater for a time period ranging from several minutes to several hours, so that the solvent is removed (which is known as pre-baking), thus adjusting the thickness of the film to 1.5 ~ 5 ㎛. Subsequently, the film is exposed to active energy rays such as UV light via a mask at an exposure dose of 30 ~ 1000 mJ/㎠. The exposure dose may vary depending on the kind of photopolymerizable composition of the light shielding film. The film obtained by the exposure is developed by dipping or spraying using a developing solution thus forming a cured film pattern. The developing solution used may include an organic material such as monoethanolamine, diethanolamine, triethanolamine or the like, or an aqueous solution such as sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, quaternary ammonium salt or the like.

After the developing process, post-baking may be performed, and specifically post-baking may be carried out at 150 ~ 250℃ for 20 ~ 40 min.

The light shielding film according to an embodiment of the present invention may satisfy appropriate light shielding properties and adequate hydrophobicity under conditions of the amount of fluorine per a cured film weight of 1 g being about 5 ~ 50 wt%.

The cured film thus obtained has appropriate light shielding properties and is adequately hydrophobic, and is thus useful for forming a light shielding pattern during the formation of color layers made using a jetting method using an ink jet print.

In addition, a display device including the color layers resulting from the photopolymerizable resin composition according to the present invention is mainly exemplified by an LCD but is not limited thereto. Various display devices requiring the color layers may include for example plasma displays, electroluminescent displays, cathode ray tubes and so on.

Also, LCDs to which the present invention may be applied are not particularly limited, and may be of various types. The display device according to the present invention may adopt any display mode such as ECB (Electrically Controlled Birefringence), TN (Twisted Nematic), IPS (In-PlaneSwitching), FLC (Ferroelectric Liquid Crystal), OCB (Optically Compensatory Bend), STN (Supper Twisted Nematic), VA (Vertically Aligned), HAN (Hybrid Aligned Nematic), GH (Guest Host) and so on. The display device having the color layers formed from the photopolymerizable resin composition according to the present invention may also be applied to large screen displays such as television monitors or displays for notebook computers.

A better understanding of the present invention may be obtained by the following examples which are set forth to illustrate, but are not to be construed as limiting the present invention.

Preparation Examples 1 to 5: Synthesis of Alkali Soluble Acrylic Binder Resin

The components shown in Table 1 below were placed into a 1000 ml four-neck flask and then stirred for 30 min while purging with nitrogen. Subsequently, the temperature was gradually increased and the reaction was carried out at 70℃ for 6 hours, and also, the temperature was increased to 80℃ and the reaction was further carried out for 2 hours, thus synthesizing an alkali soluble acrylic binder resin. In Table 1 below, units are represented by g.

*TABLE 1

Note: MAA: methacrylic acid

GMA: glycidyl methacrylate

Sty: styrene,

*KBM503: 3-(methacryloxypropyl)trimethoxysilane, available from Shin-Etsu Chemical

FA-108: 2-(perfluorooctyl)ethyl acrylate, available from Kyoeisha

Initiator: azobisisobutyronitrile

PGMEA: propyleneglycolmonomethyletheracetate

Preparation Example 6: Synthesis of Cardo based Compound

Into a 500 ml four-neck flask, 58 g of a bisphenol fluorene type epoxy resin (epoxy equivalent 232), 313 g of PGMEA, 2.5 g of triethylbenzylammonium chloride, 0.03 g of hydroquinone and 18 g of acrylic acid were added, and heated to 80 ~ 90℃ and dissolved while nitrogen was feed at a rate of 25 ml/min. The solution in a slightly opaque state was gradually heated and then completely dissolved at 80℃. Heating and stirring were continuously performed until the acid value of the solution was measured to be less than 1.0 mgKOH/g. As such, 12 hours were required to obtain a desired acid value. The solution was cooled to room temperature, thus obtaining a colorless and transparent bisphenol fluorene type epoxy acrylate.

300 g of the bisphenol fluorene type epoxy acrylate thus obtained was mixed with 14 g of 1,2,3,6-tetrahydrophthalic anhydride, 0.3 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 0.76 g of tetraethylammonium bromide, after which the resultant mixture was gradually heated and reacted at 130 ~ 140℃ for 15 hours, thus obtaining a cardo based compound.

The cardo based compound of Preparation Example 6 and the alkali soluble acrylic binder resin of each of Preparation Examples 1 to 5 were mixed with, as a pigment mixture, 130 parts by weight of a pigment dispersion solution (KLBK-90, available from Mikuni, solid content 20 wt%, containing 5 wt% of a pigment dispersant (available from BYK, disperbyk-2001) based on the total weight of the pigment dispersion solution), 2 parts by weight of a multifunctional monomer (dipentaerythritol hexaacrylate), and 5.2 parts by weight of a photoinitiator, after which the resulting mixture was blended with 90 parts by weight of a solvent (PGMEA) and 1 part by weight of other additives (a fluorine based surfactant and a coupling agent) and stirred for 3 hours, thus obtaining a photopolymerizable resin composition.

Herein, parts by weight are represented by the amount based on 100 parts by weight of solid content of the cardo based compound.

As shown in Table 2 below, in the binder resin, the acrylic binder resin and the cardo based compound were used in different amounts.

TABLE 2

Using the photopolymerizable resin composition thus obtained, a cured film pattern was formed through the following method. Specifically, the photopolymerizable resin composition was applied on a glass substrate having a clear surface using a spin coater at 320 rpm thus forming a resin coating layer. Thereafter, this layer was dried at 80℃ for 150 sec using a hot plate so that the thickness of the film was 2.2 ㎛. Subsequently, the film was exposed to active energy rays such as UV light via a mask (gap 200 ㎛) at an exposure dose of 60 mJ/㎠. The exposed film was developed using a developing solution (0.04% KOH, 23℃) (developing time 100 sec), thus forming a cured film pattern.

Thereafter, post-baking was performed at 220℃ for 30 min.

Measurement of Optical Density of Cured Film using Photopolymerizable Resin Composition

The optical density of the cured film thus obtained was measured using a reference having an optical density of 2.4 by use of a PMT device available from Otsuka Electronics. The results are shown in Table 3 below.

Measurement of Contact Angle of Cured Film using Photopolymerizable Resin Composition

5 ㎕ of water (deionized water) was dropped onto the cured film using a syringe, and the contact angle to water (deionized water) was measured.

Also, using 2-ethoxyethanol (99%, available from Aldrich) instead of water, the contact angle to 2-ethoxyethanol was measured.

As such, the contact angle was measured using E-EM03-T13-01 available from Kruss.

Measurement of Pattern Profile

The taper angle of the cured film pattern was measured using an SEM.

Residue

Whether the residue was generated or not after a developing process was observed using an SEM.

Dielectric Constant

A curing solution was applied on chromium (Cr) glass, and the entire surface thereof was exposed to light and then post-baked, thus obtaining a cured film, the dielectric constant of which was then measured at different wavelengths (100 ~ 1 MHz).

As such, the dielectric constant was measured using a thermal evaporator (E306, Edward).

Resolution

The size (width) of the pattern was measured using OM Image after development of pattern using masks having different sizes.

Measurement of Voltage Holding Ratio (VHR) of Cured Film using Photopolymerizable Resin Composition

A VHR measuring cell (manufactured by EHC), obtained by disposing a glass substrate (1 cm x 1 cm) having an ITO electrode layer for applying voltage formed thereon and a glass substrate (1 cm x 1 cm) having an ITO common electrode layer formed thereon so that the two electrode layers faced each other at a cell gap of 5 ㎛, was prepared.

The cured film was scraped off, and 0.02 g of the cured film sample and 1 g of liquid crystals (MLC-7022-100, available from Merck) were mixed in a test tube, and then aged at 65℃ for 5 hours, thus preparing a source.

The prepared source was injected into the VHR measuring cell, after which voltage was applied under the following conditions, thus measuring the VHR.

- Applied Voltage Pulse Amplitude: 5 V

- Applied Voltage Pulse Frequency: 60 Hz

- Applied Voltage Pulse Width: 16.6 msec

The VHR was measured using TOYO corporation Model 6245C, and the measurement temperature was 25℃.

The results are shown in Table 3 below.

TABLE 3

As is apparent from the results of Table 3, the cured films of Examples 5 to 20 have a contact angle to water of 95° or more and a contact angle to 2-ethoxyethanol of 40° or more, whereas the cured films of Examples 1 to 4 have a contact angle to water of 82.7° and a contact angle to 2-ethoxyethanol of 27.3°.

Thus, in the case where color ink is injected into the formed light shielding film through jetting using an ink jet print, the cured films of Examples 5 to 20 are considered to prevent problems such as the color mixing due to the color ink overflowing the barrier ribs or position deviation of the color ink in regions defined by the barrier ribs.

Consequently, Example Nos. which are regarded as optimal for preventing or minimizing the deterioration of other measurement values can be seen to be 6, 7, 10, 11, 13, 14, 17, and 18.

Claims

A photopolymerizable resin composition, which comprises an alkali soluble acrylic binder resin and a cardo based binder resin, and which satisfies all of first to third conditions as below upon formation of a resin cured film:

a first condition is that an optical density per unit thickness of 2.0 ㎛ is 2.0 or more;

a second condition is that a contact angle to water is 85°or more; and

a third condition is that a contact angle to 2-ethoxyethanol is 35°or more.
The photopolymerizable resin composition according to claim 1, wherein the contact angle to water is 85 ~ 110°upon formation of the resin cured film.
The photopolymerizable resin composition according to claim 1, wherein the contact angle to 2-ethoxyethanol is 35 ~ 50°upon formation of the resin cured film.
The photopolymerizable resin composition according to claim 1, which comprises a colorant containing a pigment mixture comprising at least two pigment components able to show a substantial black color upon mixing.
The photopolymerizable resin composition according to claim 4, wherein the pigment mixture essentially comprises a red pigment and a blue pigment, and further comprises one or more selected from among a yellow pigment, a green pigment and a violet pigment.
The photopolymerizable resin composition according to claim 5, wherein the pigment mixture comprises 10 ~ 50 wt% of the red pigment, 10 ~ 50 wt% of the blue pigment, 1 ~ 20 wt% of the yellow pigment and 1 ~ 20 wt% of the green pigment, which are expressed as a solid content, based on a total weight of the colorant.
The photopolymerizable resin composition according to claim 6, wherein the pigment mixture comprises 1 ~ 20 wt% of the violet pigment, which is expressed as a solid content, based on a total weight of the colorant.
The photopolymerizable resin composition according to claim 6, wherein the pigment mixture comprises a black pigment.
The photopolymerizable resin composition according to claim 8, wherein the black pigment is used in an amount of 15 wt% or less, which is expressed as a solid content, based on a total weight of the colorant.
The photopolymerizable resin composition according to claim 4, wherein the colorant is used in an amount of 20 ~ 80 wt% based on a total weight of the photopolymerizable resin composition.
The photopolymerizable resin composition according to claim 1, which comprises a multifunctional monomer having an ethylenically unsaturated double bond; a photoinitiator; and a solvent.
The photopolymerizable resin composition according to claim 1, wherein the alkali soluble acrylic binder resin includes an epoxy group.
The photopolymerizable resin composition according to claim 11 or 12, wherein the alkali soluble acrylic binder resin includes a fluorine group.
The photopolymerizable resin composition according to claim 13, wherein an amount of the fluorine of the alkali soluble acrylic binder resin is 5 ~ 50 wt%.
The photopolymerizable resin composition according to claim 4 or 5, wherein the pigment mixture is provided in a form of a pigment dispersion solution in which respective pigments are dispersed in a solvent.
The photopolymerizable resin composition according to claim 15, wherein the pigment dispersion solution contains at least one pigment dispersant selected from among acrylate based pigment dispersants.
The photopolymerizable resin composition according to claim 15, wherein the pigment dispersion solution contains 3 ~ 20 wt% of the pigment dispersant based on a total weight of the pigment dispersion solution.
The photopolymerizable resin composition according to claim 15, wherein the pigment dispersion solution comprises a fluorine group-containing acrylic binder resin.
The photopolymerizable resin composition according to claim 1, wherein the cardo based binder resin contains a fluorine group.
The photopolymerizable resin composition according to claim 1, which comprises a fluorine group-containing epoxy monomer.
The photopolymerizable resin composition according to claim 1, which comprises a fluorine group-containing siloxane based monomer.
The photopolymerizable resin composition according to claim 1, wherein the fluorine is contained in an amount of 5 ~ 50 wt% per a cured film weight of 1 g upon formation of the cured film.
A color filter substrate, comprising a black matrix formed by photolithography using the photopolymerizable resin composition of claim 1.
A thin film transistor substrate, comprising a black matrix formed by photolithography using the photopolymerizable resin composition of claim 1.
An image display device, comprising the color filter substrate of claim 23 as an upper substrate.
An image display device, comprising the thin film transistor substrate of claim 24 as a lower substrate.