JP7500478B2 - White photosensitive resin composition, color filter and image display device produced using the same - Google Patents

Description

The present invention relates to a white photosensitive resin composition, and a color filter and an image display device manufactured using the same.

A color filter is a thin-film optical component that extracts the three colors red, green, and blue from white light and makes them possible to produce minute pixel units, with each pixel measuring tens to hundreds of micrometers. Such color filters are constructed by stacking a black matrix layer formed in a specified pattern on a transparent substrate to block the boundaries between each pixel, and a pixel section in which the three primary colors (usually red (R), green (G), and blue (B)) are arranged in a specified order to form each pixel.

Recently, one method of creating color filters has been the pigment dispersion method, which uses pigment-dispersed photosensitive resins. However, as the light emitted from the light source passes through the color filter, some of the light is absorbed by the color filter, reducing the light efficiency. In addition, there are problems with poor color reproduction due to the characteristics of the pigments contained in the color filter.

In particular, color filters are used in a variety of fields, including various image display devices, and therefore require not only excellent pattern characteristics but also high color reproduction rate as well as other performance characteristics such as high brightness and high contrast ratio. In order to solve these problems, a method for manufacturing color filters using a spontaneous light-emitting photosensitive resin composition containing quantum dots has been proposed.

For example, Korean Patent Registration No. 10-1906279 discloses a photosensitive resin composition containing quantum dots, a binder resin, a photopolymerizable monomer, a photopolymerization initiator, a diffusing agent, a polymerization inhibitor, a thiol-based additive, and a solvent, and a technology relating to a color filter using the same.

However, in the case of color filters containing quantum dots as described in the above patent document, the efficiency of the quantum dots, especially the efficiency of the blue quantum dots, can decrease, which can slightly decrease the performance of the color conversion panel, and in the case of blue quantum dots, they are expensive, which can increase the overall manufacturing costs.

In the case of a display that includes a color conversion panel that uses a blue light source, the green and red pixels produce colors using green and red quantum dots, respectively. However, as mentioned above, blue is difficult to use due to performance issues with blue quantum dots, so the color is produced by transmitting the blue light source. For this reason, green and red generate light that is scattered by the quantum dots, while blue generates direct light, making it difficult to mix colors clearly when mixing them. To solve these problems, technology has been developed to introduce a scattering layer for the purpose of scattering into the blue pixels.

Therefore, in order to prevent a decrease in the efficiency of blue pixels, there is currently a demand for the development of a photosensitive resin composition that can solve the problem of reduced brightness and ensure an excellent viewing angle.

Republic of Korea Patent No. 10-1906279

One objective of the present invention is to provide a white photosensitive resin composition suitable for producing a blue pixel layer that can prevent a decrease in luminance and provide an excellent viewing angle.

The present invention also aims to provide a color filter including a coating film produced using the white photosensitive resin composition, and an image display device including the color filter.

The present invention relates to an ink-transmitting material comprising: (A) a scattering particle or a mixture of a scattering particle and a colorant; (B) an alkali-soluble resin; (C) a polymerizable compound; (D) a photopolymerization initiator; and (E) a solvent;
The present invention provides a white photosensitive resin composition, which, when a coating film having a thickness of 10 μm is formed, has a luminance of 60% or more based on 100% of a blue light source.

The present invention also provides a color filter including a coating film made from the white photosensitive resin composition.

Furthermore, the present invention provides an image display device including the color filter.

By manufacturing a blue pixel using the white photosensitive resin composition of the present invention, it is possible to mitigate the significant decrease in brightness caused by the light emitted from a blue light source passing through the blue pixel of the present invention, and it is possible to ensure an excellent viewing angle and prevent a decrease in the efficiency of the blue pixel.

Therefore, a color filter containing a coating film produced using the white photosensitive resin composition of the present invention as a blue pixel and an image display device containing the color filter can provide excellent effects in terms of image quality, viewing angle, etc.

The present invention provides a white photosensitive resin composition that includes (A) scattering particles, (B) an alkali-soluble resin, (C) a polymerizable compound, (D) a photopolymerization initiator, and (E) a solvent, and that, when a coating film having a thickness of 10 μm is formed, the brightness of the coating film produced is 60% or more based on 100% blue light source. The present invention also provides a color filter and an image display device that include a coating film produced using the white photosensitive resin composition.

For example, the red and green pixel layers containing quantum dots are formed to a thickness of 8 to 15 μm so that the more quantum dots they contain, the higher the luminance of the emitted light, and so that when a large number of quantum dots are contained, the quantum dots do not aggregate and the luminance of the emitted light does not decrease. Therefore, the blue pixel (scattering pixel) layer included in the color filter together with the red and green pixel layers is also formed in the above thickness range.

Furthermore, when blue is used as a light source, the light emitted from the light source passes through the blue pixel, reducing the light efficiency, and the blue pixel cannot maintain the brightness of the blue light source, resulting in a brightness that is significantly reduced compared to the brightness of the blue light source.

Therefore, the present invention provides a white photosensitive resin composition that ensures that the luminance of the coating film produced is 60% or more compared to the luminance of a blue light source when a coating film with a thickness of 10 μm is used as a reference, so that a color filter and an image display device including a pixel layer formed in a thick film with a thickness of 8 to 15 μm can achieve excellent color reproducibility and image quality.

In addition, the white photosensitive resin composition of the present invention, when formed into a coating film having a thickness of 10 μm, exhibits a brightness of 50% or more in the range of viewing angles from -60° to +60° based on a front viewing angle of 0°, thereby preventing a decrease in efficiency due to the viewing angle of blue pixels. Preferably, the white photosensitive resin composition of the present invention, when cured, has a brightness of 80% or more, more preferably 90% or more, in the range of viewing angles from -60° to +60° based on a front viewing angle of 0°.

As a result, the present invention achieves a value of "luminance (A) relative to blue light source x luminance (B) at viewing angle" of 50% or more, providing an image display device with excellent color reproducibility and visibility.

In the present invention, a blue light source can mean having a wavelength of 380 nm to 530 nm.

The components constituting the white photosensitive resin composition of the present invention are described in detail below. However, the present invention is not limited to these components.

<White Photosensitive Resin Composition>
The white photosensitive resin composition according to the present invention contains scattering particles or a mixture of scattering particles and a colorant, an alkali-soluble resin, a polymerizable compound, a photopolymerization initiator, and a solvent, and may further contain optional additives as necessary.

(A) Scattering Particles or a Mixture of Scattering Particles and a Colorant The white photosensitive resin composition according to the present invention contains scattering particles to provide a light scattering effect.

The white photosensitive resin composition of the present invention containing the scattering particles can be suitably used to act as a blue pixel when exposed to a blue light source.

In the present invention, the scattering particles include a metal oxide.
The metal oxide may include one or more oxides selected from the group consisting of Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Mo, Cs, Ba, La, Hf, W, Tl, Pb, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Ti, Sb, Sn, Zr, Nb, Ce, Ta, In, and combinations thereof.

For example, the metal oxide may include one _{or more selected from the group consisting of Al2O3, SiO2, ZnO, ZrO2, BaTiO3, TiO2, Ta2O5, Ti3O5 , ITO , IZO , ATO , ZnO - Al} , _Nb2O3 , SnO, MgO, and combinations thereof, and if necessary, a material that has been surface-treated with a compound having an unsaturated bond such as acrylate may also be used.

The scattering particles can be used with a limited average particle size and content in the overall composition to maximize the luminous intensity of the color filter.

In the present invention, the "average particle size" may be a number-average particle size, and may be determined, for example, from an image observed with a field emission scanning electron microscope (FE-SEM) or a transmission electron microscope (TEM). Specifically, it can be obtained by extracting several samples from the FE-SEM or TEM observation images, measuring the diameters of these samples, and taking the arithmetic average value.

For example, the metal oxide contained in the scattering particles of the present invention may have an average particle size of 30 to 500 nm, preferably 30 to 300 nm. When the average particle size of the metal oxide satisfies the above range, the scattering effect is increased, and the white photosensitive resin composition containing the scattering particles can act as a blue pixel under a blue light source, which is preferable. In addition, the phenomenon of sinking in the composition can be prevented, and a surface of uniform quality can be obtained, so the average particle size can be appropriately adjusted within the above range.

In some embodiments, the white photosensitive resin composition of the present invention may contain two types of scattering particles, in which case the scattering particles may have different average particle sizes.

For example, scattering particles with an average particle size of 100 nm or more can be used in combination with scattering particles with an average particle size of less than 100 nm.

In the present invention, when two types of scattering particles having different average particle sizes are used, it is preferable that the particle size ratio of the two types of scattering particles satisfies the following formula 1, which is advantageous in terms of the color reproduction rate of the color filter/image display device.

When the above formula 1 is satisfied, there is an advantage that the color reproducibility of the color filter is excellent.
The scattering particles are contained in an amount of 0.1 to 11 parts by weight based on 100 parts by weight of the total solid content in the white photosensitive resin composition. When the scattering particles are contained within the above range, there is an advantage that a scattering pixel having excellent luminescence intensity can be manufactured. Specifically, when the scattering particles are contained within the above range, there is an advantage that the desired luminescence intensity can be easily secured and a decrease in the stability of the composition can be suppressed.

On the other hand, the white photosensitive resin composition of the present invention can be used to function as a blue pixel by a blue light source when cured, that is, a blue pixel that can transmit the blue light source through the cured coating film as it is. It is preferable that the white photosensitive resin composition of the present invention does not substantially contain a colorant in order to improve the transmission efficiency of blue light, but it is also possible to contain a small amount of a colorant other than the above-mentioned scattering particles as necessary, taking into account other properties required of the composition.

In the present invention, the colorant means a color material excluding the scattering particles.
For example, blue-based colorants include, but are not limited to, C.I. Pigment Blue 15:6, C.I. Pigment Blue 16, C.I. Pigment Blue 60, and Violet 29. In one embodiment of the present invention, when the scattering particles and the colorant are simultaneously contained, it is preferable that the content ratio of the scattering particles and the colorant satisfies the following formula 2.

When the above formula 2 is satisfied, there is an advantage that the emission intensity can be easily ensured.
As described above, the white photosensitive resin composition according to the present invention can be used by mixing scattering particles and a colorant, but it is more preferable that the composition contains only scattering particles in order to improve the transmission efficiency of blue light and ensure excellent brightness and viewing angle.

(B) Alkali-soluble resin The alkali-soluble resin can be selected from resins known in this field without any particular restrictions, so long as it has reactivity due to the action of light or heat, is alkali-soluble, acts as a dispersion medium for solids including scattering particles, and functions as a binder resin.

Specifically, the alkali-soluble resin is preferably a copolymer of an unsaturated carboxyl group-containing monomer and another monomer that is copolymerizable therewith.

Examples of the unsaturated carboxyl group-containing monomer include unsaturated carboxylic acids having one or more carboxyl groups in the molecule, such as unsaturated monocarboxylic acids, unsaturated dicarboxylic acids, and unsaturated tricarboxylic acids.

Examples of the unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, α-chloroacrylic acid, and cinnamic acid.

Examples of the unsaturated dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid.

The unsaturated polycarboxylic acid may be an acid anhydride, and specific examples thereof include maleic anhydride, itaconic anhydride, and citraconic anhydride. The unsaturated polycarboxylic acid may be a mono(2-methacryloyloxyalkyl)ester thereof, such as mono(2-acryloyloxyethyl) succinate, mono(2-methacryloyloxyethyl) succinate, mono(2-acryloyloxyethyl) phthalate, and mono(2-methacryloyloxyethyl) phthalate. The unsaturated polycarboxylic acid may be a mono(meth)acrylate of a dicarboxy polymer at both ends thereof, such as ω-carboxypolycaprolactone monoacrylate and ω-carboxypolycaprolactone monomethacrylate.

The carboxyl group-containing monomers can be used alone or in combination of two or more.

Examples of other monomers copolymerizable with the carboxyl group-containing monomer include aromatic vinyl compounds such as styrene, α-methylstyrene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene, p-chlorostyrene, o-methoxystyrene, m-methoxystyrene, p-methoxystyrene, o-vinylbenzyl methyl ether, m-vinylbenzyl methyl ether, p-vinylbenzyl methyl ether, o-vinylbenzyl glycidyl ether, m-vinylbenzyl glycidyl ether, p-vinylbenzyl glycidyl ether, and indene; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, i-propyl acrylate, i-propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, sec-butyl acrylate, sec-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl meth ... methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 3-hydroxybutyl acrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, allyl acrylate, allyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, phenyl acrylate, phenyl methacrylate, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, 2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate, methoxydiethylene glycol acrylate, methoxydiethylene glycol methacrylate, methoxytriethylene glycol acrylate, methoxytriethylene glycol methacrylate, methoxypropylene glycol acrylate, methoxypropylene glycol unsaturated carboxylic acid esters such as methacrylate, methoxydipropylene glycol acrylate, methoxydipropylene glycol methacrylate, isobornyl acrylate, isobornyl methacrylate, dicyclopentadienyl acrylate, dicyclopentadiethyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-phenoxypropyl methacrylate, glycerol monoacrylate, and glycerol monomethacrylate; unsaturated carboxylic acid amino alkyl esters such as 2-aminoethyl acrylate, 2-aminoethyl methacrylate, 2-dimethylaminoethyl acrylate, 2-dimethylaminoethyl methacrylate, 2-aminopropyl acrylate, 2-aminopropyl methacrylate, 2-dimethylaminopropyl acrylate, 2-dimethylaminopropyl methacrylate, 3-aminopropyl acrylate, 3-aminopropyl methacrylate, 3-dimethylaminopropyl acrylate, and 3-dimethylaminopropyl methacrylate; glycidyl acrylate, glycidyl unsaturated carboxylic acid glycidyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, and other vinyl carboxylates; unsaturated ethers such as vinyl methyl ether, vinyl ethyl ether, and allyl glycidyl ether; vinyl cyanide compounds such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and vinylidene cyanide; acrylamide, methacrylamide, α-chloroacrylamide, N-2-hydroxyethylacrylamide, and N-2-hydroxyethyl acrylamide; Examples of such monomers include unsaturated amides such as ethyl methacrylamide; unsaturated imides such as maleimide, N-phenylmaleimide, N-cyclohexylmaleimide, and N-benzylmaleimide; aliphatic conjugated dienes such as 1,3-butadiene, isoprene, and chloroprene; and macromonomers having a monoacryloyl group or monomethacryloyl group at the end of the polymer molecular chain, such as polystyrene, polymethyl acrylate, polymethyl methacrylate, poly-n-butyl acrylate, poly-n-butyl methacrylate, and polysiloxane. These monomers can be used alone or in combination of two or more.

In the present invention, the alkali-soluble resin (B) is contained in an amount of 20 to 70 parts by weight, preferably 25 to 65 parts by weight, and more preferably 30 to 60 parts by weight, per 100 parts by weight of the total solid content in the white photosensitive resin composition.

When the alkali-soluble resin (B) is within the above range, it has the advantage that it is sufficiently soluble in the developer, making it easy to form a cured film, and preventing film reduction in the pixel parts of the exposed area during development, making it easy to remove non-pixel parts. In addition, when the alkali-soluble resin (B) of the present invention is contained, it has the advantage that it is easy to form a pattern of the same line width even when the development process in which a pattern is formed using a developer is changed.

(C) Polymerizable Compound The polymerizable compound contained in the white photosensitive resin composition of the present invention is a compound that can be polymerized by light and heat. Any polymerizable compound known in this field can be selected and used without any particular limitation as long as it can be polymerized by light and heat. Specific examples of the polymerizable compound include monofunctional monomers, bifunctional monomers, and other polyfunctional monomers.

The type of the monofunctional monomer is not particularly limited, and examples include nonylphenylcarbitol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-ethylhexylcarbitol acrylate, 2-hydroxyethyl acrylate, and N-vinylpyrrolidone.

The type of the bifunctional monomer is not particularly limited, and examples include 1,6-hexanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, bis(acryloyloxyethyl)ether of bisphenol A, and 3-methylpentanediol di(meth)acrylate.

The type of the polyfunctional monomer is not particularly limited, and examples thereof include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, ethoxylated dipentaerythritol hexa(meth)acrylate, propoxylated dipentaerythritol hexa(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

Commercially available examples of the double bond monomer include, but are not limited to, Miramer M600 from Miwon Trading Co., Ltd.

In the present invention, the polymerizable compound is contained in an amount of 5 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the total solid content in the white photosensitive resin composition. When contained within the above range, there is an advantage that it is preferable in terms of the strength and smoothness of the pixel part.

(D) Photopolymerization Initiator The white photosensitive resin composition according to the present invention contains a photopolymerization initiator.

The photopolymerization initiator may be any photopolymerization initiator commonly used in white photosensitive resin compositions. For example, acetophenone-based, benzophenone-based, triazine-based, thioxanthone-based, oxime-based, benzoin-based, and biimidazole-based compounds may be used.

For example, oxime compounds include o-ethoxycarbonyl-α-oximino-1-phenylpropan-1-one, and representative commercially available products include OXE-01 and OXE-02 from Ciba.

The photopolymerization initiator can be used in an amount of 0.01 to 10 parts by weight, preferably 0.01 to 5 parts by weight, per 100 parts by weight (based on solid content) of the white photosensitive resin composition. This content range takes into consideration the photopolymerization rate of the photopolymerizable compound and the physical properties of the final coating film. If the content is less than this range, the polymerization rate is low and the overall process time is long, and conversely, if the content exceeds this range, excessive crosslinking reaction may occur due to excessive reaction, which may actually deteriorate the physical properties of the coating film, so it is used appropriately within this range.

If necessary, a photopolymerization initiator assistant can be used together with the photopolymerization initiator. When a photopolymerization initiator assistant is used together with the photopolymerization initiator, the photosensitive resin composition for scattering pixels becomes even more sensitive, and productivity is improved, which is preferable. As the photopolymerization initiator assistant, one or more compounds selected from the group consisting of amines and carboxylic acid compounds can be suitably used.

Such photopolymerization initiator aids are usually used in an amount of 10 moles or less, preferably 0.01 to 5 moles, per mole of photopolymerization initiator. When the photopolymerization initiator aid is used within the above range, it is expected that the polymerization efficiency will be increased, resulting in improved productivity.

(E) Solvent The solvent contained in the white photosensitive resin composition of the present invention is not particularly limited, and various organic solvents known in the field of photosensitive resin compositions can be used.

For example, solvents that can be used in the present invention include ethylene glycol monoalkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and ethylene glycol monobutyl ether; diethylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether; ethylene glycol alkyl ether acetates such as methyl cellosolve acetate and ethyl cellosolve acetate; propylene glycol monomethyl ether acetate; Examples of such esters include alkylene glycol alkyl ether acetates such as ethyl ether acetate, propylene glycol monopropyl ether acetate, methoxybutyl acetate, and methoxypentyl acetate; aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; ketones such as methyl ethyl ketone, acetone, methyl amyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, and glycerin; esters such as ethyl 3-ethoxypropionate and methyl 3-methoxypropionate; and cyclic esters such as gamma-butyrolactone.

Among the above-mentioned solvents, in terms of coatability and drying property, organic solvents having a boiling point of 100°C to 200°C are preferably used, more preferably alkylene glycol alkyl ether acetates, ketones, esters such as ethyl 3-ethoxypropionate and methyl 3-methoxypropionate, and even more preferably propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, cyclohexanone, ethyl 3-ethoxypropionate, methyl 3-methoxypropionate, etc. These solvents can be used alone or in combination of two or more kinds.

The content of the solvent is usually 30 to 90 parts by weight, preferably 35 to 85 parts by weight, based on 100 parts by weight of the total white photosensitive resin composition including the solvent. When the content of the solvent is within the above range, the coating properties tend to be good when applied with a coating device such as a roll coater, spin coater, slit and spin coater, slit coater (sometimes called a die coater), or inkjet, which is preferable.

(F) Additives The white photosensitive resin composition according to one embodiment of the present invention may further contain an additive. The type of the additive is determined according to the needs of the user and is not particularly limited in the present invention. Examples of the additive include a filler, another polymer compound, a heat curing agent, a surfactant, an adhesion promoter, an antioxidant, an anti-aggregation agent, and a leveling agent.

Examples of the filler include glass, silica, and alumina.
Specific examples of the other polymer compounds include curable resins such as epoxy resins and maleimide resins, and thermoplastic resins such as polyvinyl alcohol, polyacrylic acid, polyethylene glycol monoalkyl ether, polyfluoroalkyl acrylate, polyester, and polyurethane.

For additives whose contents are not exemplified among the additives, those skilled in the art can add them as appropriate within the range that does not impair the effects of the present invention. For example, the additives can be used in an amount of 0.05 to 30 parts by weight, preferably 0.1 to 20 parts by weight, per 100 parts by weight of the white photosensitive resin composition, but are not limited thereto.

According to one embodiment of the present invention, the additive may include an antioxidant. When an antioxidant is further included in this manner, there is an advantage in that it is possible to prevent aging due to heat during post-baking during the process of forming a cured product and to expect the effect of preserving color.

The antioxidant may include, for example, one or more selected from the group consisting of phosphorus-based antioxidants, sulfur-based antioxidants, and phenol-based antioxidants. In this case, discoloration that may occur at high temperatures during the process or yellowing that may be caused by a light source after the display is manufactured can be suppressed. The antioxidant may include one or more selected from the group consisting of phenolic compounds, phosphorus-based compounds, and sulfur-based compounds, and these can be used in combination as phenolic-phosphorus compounds, phenolic-sulfur compounds, phosphorus-sulfur compounds, or phenolic-phosphorus-sulfur compounds.

For example, among the above-mentioned phenol-based antioxidants, in terms of heat resistance and prevention of heat discoloration, 3,9-bis[2-[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethoxy]-2,4,8,10-tetraoxaspiro[5.5]undecane, 1,3,5-trimethyl-2,4,6-tris(3'5'-di-t-butyl-4-hydroxybenzyl)benzene, pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 4,4'-thiobis(6-t-butyl-3-methylphenol), tris -(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-isocyanurate, 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and 2,4-bis[(octylthio)methyl]-O-cresol are preferred.

Commercially available products include Irganox 1010 (manufactured by BASF), Sumilizer BBM-S (manufactured by Sumitomo Chemical), ADK STAB AO-80 (manufactured by ADEKA), Sumilizer GP (manufactured by Sumitomo Chemical), and Irganox 1035 (manufactured by BASF).

The antioxidant is contained in an amount of 0.1 to 30 parts by weight, preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the total solid content of the white photosensitive resin composition of the present invention. When the content of the antioxidant is within the above range, it is advantageous in terms of solving the problem of reduced luminescence intensity.

The white photosensitive resin composition of the present invention can be produced by a method known in the art and is not particularly limited in the present invention. One example of the method is as follows:

The scattering particles are mixed with a solvent in advance and dispersed using a bead mill or the like until the average particle size is 30 to 300 nm. At this time, a dispersant may be additionally used as necessary, and some or all of the alkali-soluble resin may be blended. The remaining alkali-soluble resin, polymerizable compound, photopolymerization initiator, other components used as necessary, and additional solvent as necessary are further added to the obtained dispersion (hereinafter sometimes referred to as mill base) to a predetermined concentration, thereby obtaining the desired white photosensitive resin composition.

<Scattered pixels>
The present invention provides a scattering pixel, i.e., a blue pixel, fabricated using the above-mentioned white photosensitive resin composition.

The scattering pixel is a coating film formed by applying the above-mentioned white photosensitive resin composition on a substrate, exposing and developing it in a predetermined pattern. The white photosensitive resin composition of the present invention used to form the coating film does not contain quantum dots, and preferably does not substantially contain any other colorant other than the above-mentioned scattering particles in order to improve the transmission efficiency of blue light. However, the white photosensitive resin composition for producing the scattering pixel of the present invention may contain a small amount of colorant depending on the characteristics required for the scattering pixel.

The scattering pixel of the present invention is more suitable for use in image display devices, and may refer to a blue pixel layer that exhibits a blue color by transmitting blue light directly from a blue light source.

The scattering pixel of the present invention is more suitable for use in quantum dot displays that use a blue light source. For example, the red and green pixel layers realize images using scattered light, in which quantum dots located in each pixel are converted to red and green by blue light, respectively, while the blue pixel layer uses a blue light source as is. At this time, the blue light source transmits direct light, making it difficult to realize the desired color, and scattered light is also required for blue. For this reason, the white photosensitive resin composition of the present invention is used in the blue pixel layer to impart a scattering effect.

The scattering pixel according to the present invention is manufactured from the above-mentioned white photosensitive resin composition, which allows for reduced manufacturing costs. In addition, it has the advantage that not only can it mitigate the significant decrease in luminance caused by the light emitted from a blue light source passing through the blue pixel of the present invention, but it also has the advantage of improving the transmittance and providing an excellent viewing angle.

<Color filter>
The present invention provides a color filter that includes the scattering pixels described above.

When the color filter of the present invention is applied to an image display device, it emits light using the light source of the display device, and therefore can achieve better light efficiency. In addition, since light having a hue is emitted, it has better color reproducibility, and since light is emitted in all directions by photoluminescence, the viewing angle is improved and the brightness characteristics are excellent.

In the present invention, by using a light source that emits blue light, the red pattern layer or the green pattern layer can emit red light or green light, respectively, depending on the light source that emits blue light, and the scattering pixels can exhibit blue color because the blue light is transmitted directly without color conversion, unlike those using a conventional white light source.

The substrate is not particularly limited and may be the substrate of the color filter itself or the portion of a display device where the color filter is located. The substrate may be glass, silicon (Si), silicon oxide (SiOx), or a polymer substrate, and the polymer substrate may be polyethersulfone (PES) or polycarbonate (PC), etc.

In the present invention, the scattering pixels may not contain quantum dots, and the red and green pattern layers may contain quantum dots.

The pattern layer may be a coating film formed by applying a colored photosensitive resin composition known in the technical field of the present invention, exposing it to a predetermined pattern, developing it, and thermally curing it, or the pattern layer may be formed by a method commonly known in the art.

A light source that emits blue light can be used as the light source of an image display device including the color filter according to the present invention. In this case, the red pattern layer emits red light, the green pattern layer emits green light, and the scattering pixels transmit the blue light as it is, resulting in a blue color.

<Image display device>
The present invention provides an image display device comprising a scattering layer, i.e. a scattering pixel, according to the present invention.

For example, the image display device may be a liquid crystal display (liquid crystal display device; LCD), an organic electroluminescence display (organic electroluminescence display device), a quantum dot display, a liquid crystal projector, a display device for a game console, a display device for a mobile terminal such as a mobile phone, a display device for a digital camera, a display device for a car navigation system, or the like, and the image display device according to one embodiment of the present invention may be a quantum dot display.

The image display device may include other components that are typically included in an image display device, such as a light-emitting device such as a light source, a light guide plate, and a liquid crystal display unit including a color filter, and is not limited to these in the present invention.

In the present invention, the light emitted by the light source applied to the image display device is not particularly limited, but in terms of better color reproducibility, a light source that emits blue light can be preferably used.

The present invention will be described in more detail below based on examples, but the embodiments of the present invention disclosed below are merely illustrative, and the scope of the present invention is not limited to these embodiments. The scope of the present invention is set forth in the claims, and includes all modifications that have the same meaning and scope as those recorded in the claims. In the following examples and comparative examples, the units "%" and "parts" indicating the content are by weight unless otherwise specified.

<Synthesis Example>
Synthesis Example 1: Synthesis of alkali-soluble resin (B)
A flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel, and a nitrogen inlet tube was prepared. On the one hand, 15 parts by weight of N-benzylmaleimide, 30 parts by weight of acrylic acid, 50 parts by weight of cyclohexyl methacrylate, 5 parts by weight of methyl methacrylate, 4 parts by weight of t-butylperoxy-2-ethylhexanoate, and 40 parts by weight of propylene glycol monomethyl ether acetate (hereinafter also referred to as PGMEA) were charged and then stirred and mixed to prepare a monomer dropping funnel. On the other hand, 6 parts by weight of n-dodecanediol and 24 parts by weight of PGMEA were charged and then stirred and mixed to prepare a chain transfer agent dropping funnel.

After that, 395 parts by weight of PGMEA was introduced into the flask, the atmosphere in the flask was replaced from air to nitrogen, and the temperature of the flask was raised to 90°C while stirring. Next, the monomer and chain transfer agent were started to be dropped from the dropping funnel. The dropping was continued for 2 hours while maintaining the temperature at 90°C, and after 1 hour, the temperature was raised to 110°C and maintained for 3 hours, after which a gas inlet tube was introduced and bubbling of a mixed gas of oxygen/nitrogen = 5/95 (v/v) was started.

Next, 20 parts by weight of glycidyl methacrylate, 0.4 parts by weight of 2,2'-methylenebis(4-methyl-6-t-butylphenol), and 0.8 parts by weight of triethylamine were added to the flask and the reaction was continued at 110°C for 6 hours. After that, the mixture was cooled to room temperature to obtain an alkali-soluble resin with a weight average molecular weight of 3,800 and an acid value based on the solid content of 83 mgKOH/g.

Examples and Comparative Examples: Preparation of White Photosensitive Resin Compositions White photosensitive resin compositions were prepared according to the compositions (units: weight %) shown in Tables 1 and 2 below.

(A-1) Scattering particles: TiO ₂ (DuPont R102, 210 nm)
(A-2) Scattering particles: TiO ₂ (Ishihara's TTO-55(c), 30-50 nm)
(A-3) Colorant: Blue pigment, Blue 15:6 (TCI chemical)
(A-4) Colorant: purple pigment, Violet 29 (TCI chemical)
(B) Alkali-soluble resin: Synthesis Example 1
(C) Polymerizable compound: dipentaerythritol hexaacrylate (Kayarad DPHA, Nippon Kagaku)
(D) Photopolymerization initiator: Irgacure OXE01 (BASF)
(E-1) Antioxidant: Sumilizer GP (Sumitomo Chemical)
(E-2) Epoxy resin: ESCN 195XL (Sumitomo Chemical)
(E-3) Leveling agent: F-554 (DIC Corporation)
(F) Solvent: Propylene glycol monomethyl ether acetate (PGMEA)
<Fabrication of Scattering Pixels>
A scattering pixel was manufactured using the white photosensitive resin composition manufactured according to the examples and comparative examples. That is, each of the white photosensitive resin compositions was applied onto a glass substrate by spin coating, and then placed on a heating plate and maintained at 100° C. for 3 minutes to remove the solvent and form a coating film.

Next, a test photomask with a square transmission pattern of 20 mm x 20 mm and a line pattern of 1 to 100 μm was placed on the coating film, and ultraviolet light was irradiated with a distance of 100 μm from the test photomask.

At this time, the ultraviolet light source was an ultra-high pressure mercury lamp (product name USH-250D) manufactured by Ushio Inc., and light was irradiated at an exposure dose of 200 mJ/ ^cm2 (based on 365 nm) in an air atmosphere, without using any special optical filter.

The UV-irradiated coating was developed by immersing it in a pH 10.5 KOH aqueous solution developer for a set time (80 seconds and 160 seconds, respectively). The glass substrate on which the coating was formed was washed with distilled water, dried by blowing nitrogen gas, and heated in a heating oven at 230°C for 20 minutes to produce a hardened film of a scattering pixel pattern. The film thickness of the scattering pixel produced was 10 μm.

<Experimental Example>
Experimental Example 1: Luminance of blue light source contrast
The transmittance of the blue light source was measured using a CAS 140 CT (Instrument System Co.). First, bare glass was placed on a blue light source (450 nm) and the brightness was measured with a detector to obtain a reference. Then, a 10 μm thick coating film prepared using the photosensitive resin composition prepared according to the examples and comparative examples was placed on a substrate at the same position and the brightness was measured. The brightness of each example and comparative example was then measured in comparison with the brightness of the blue light source. The results are shown in Table 3 below (brightness mW/ ^cm2 ).

Experimental Example 2: Measurement of viewing angle with respect to a blue light source The viewing angle of the coated substrates prepared using the photosensitive resin compositions prepared in the above Examples and Comparative Examples was measured using an EZCON device. The results are shown in Table 3 below (brightness at viewing angle 60°). In addition, the color reproducibility and visibility of the image display device were evaluated based on the measured viewing angle, and the results are shown in Table 3 below.
<Evaluation criteria for color reproduction and visibility>

○: The value calculated by the above formula 3 is 50% or more;
×: The value calculated by the above formula 3 is less than 50%

Referring to Table 3, when the white photosensitive resin composition according to the embodiment of the present invention is used, the brightness of the coating film produced can be secured to be 60% or more compared to the brightness of the blue light source when the coating film is based on a thickness of 10 μm. Specifically, it was found that Examples 1 to 8 show relatively higher brightness values compared to Comparative Examples 1 and 4. It was found that, when a coating film of a thickness of 10 μm is formed, the brightness of the coating film produced is less than 60% when based on 100% of the blue light source, and the brightness value is significantly reduced in Comparative Examples 1 to 4. From this, it can be seen that if a thick pixel layer is formed using the composition according to Comparative Examples 1 to 4, the color reproducibility and image quality of the color filter/image display device including the same is significantly reduced.

In addition, when the white photosensitive resin composition according to the embodiment of the present invention is used, excellent brightness at a viewing angle can be ensured based on a coating film having a thickness of 10 μm. In particular, it was found that the composition of Example 4 using one type of scattering particle can be more advantageous in ensuring brightness at a viewing angle than Example 6 using two types of scattering particles. Therefore, when using two types of scattering particles, it is advantageous for the color reproducibility and image quality of the color filter/image display device if the particle size ratio satisfies "scattering particles with an average particle size of 100 nm or more/particles with an average particle size of less than 100 nm ≧ 1".

In summary, the embodiments of the present invention not only exhibit excellent luminance in blue light source contrast, but also excellent characteristics in luminance at the viewing angle, and it has been found that the image display device exhibits excellent characteristics in color reproducibility and visibility taking into account the luminance in blue light source contrast and the luminance at the viewing angle.

Claims (8)

A white photosensitive resin composition comprising (A) scattering particles or a mixture of scattering particles and a colorant, (B) an alkali-soluble resin, (C) a polymerizable compound, (D) a photopolymerization initiator, and (E) a solvent, the white photosensitive resin composition not including quantum dots,
The scattering particles include two types having different average particle sizes, the two types of scattering particles having different average particle sizes being particles having an average particle size of 100 nm or more and particles having an average particle size of less than 100 nm, and the two types of scattering particles having different average particle sizes have a particle weight ratio that satisfies the following formula 1:

the scattering particles are contained in an amount of 0.1 to 11 parts by weight based on 100 parts by weight of the total solid content in the white photosensitive resin composition;
A white photosensitive resin composition, in which the luminance of a coating film having a thickness of 10 μm is 60% or more based on 100% of a blue light source. 2. The white photosensitive resin composition according to claim 1, wherein when the white photosensitive resin composition contains a mixture of the scattering particles and the colorant, the ratio of the contents of the scattering particles and the colorant satisfies the following formula 2:

The white photosensitive resin composition according to claim 1, which has a luminance of 50% or more at viewing angles of -60° to +60° with respect to a front viewing angle of 0° when a coating film having a thickness of 10 μm is formed. The white photosensitive resin composition according to claim 1, which is for producing scattering pixels that exhibit a blue color when exposed to a blue light source. The white photosensitive resin composition according to claim 1, further comprising one or more additives selected from fillers, other polymer compounds, heat curing agents, surfactants, adhesion promoters, antioxidants, anti-aggregation agents, and dispersants. A scattering pixel manufactured using the white photosensitive resin composition according to claim 1. A color filter comprising the scattering pixel of claim 6 . An image display device comprising the color filter according to claim 7 .