Ink composition, film and display device using same

Abstract

Provided are an ink composition comprising (A) semiconductor nanorods; and (B) a solvent containing at least one diol compound, and having a viscosity of 50 cps or more at 20°C to 25°C and 20 cps or less at 35°C to 65°C, a film produced using the ink composition, and a display device including the film.

Description

[Technical field]

[0001] This description relates to ink compositions, films and display devices utilizing same. [Background technology]

[0002] LEDs have been actively developed since Nakamura of Nichia Chemical Company in Japan succeeded in fusing high-quality single crystal GaN nitride semiconductors by applying a low-temperature GaN compound buffer layer in 1992. LEDs are semiconductor devices that utilize the characteristics of compound semiconductors to convert electrical signals into light with a desired wavelength band.

[0003] Such LED semiconductors are called a revolution in light as they are environmentally friendly, with extremely low energy consumption due to their high light conversion efficiency, semi-permanent lifespan, and green materials. Recently, high-brightness red, orange, green, blue, and white LEDs have been developed with the advancement of compound semiconductor technology, and these are being used in many fields such as traffic lights, mobile phones, car headlights, outdoor light displays, LCD BLUs (back light units), and indoor and outdoor lighting, and active research is continuing both at home and abroad. In particular, GaN-based compound semiconductors, which have a wide band gap, are used to manufacture LED semiconductors that emit light in the green, blue, and ultraviolet regions, and since it is possible to manufacture white LED elements using blue LED elements, much research is being conducted on this topic.

[0004] Among these research projects, active research is being conducted on ultra-small LED elements, which are manufactured in nano or micro units, and research is ongoing to use these ultra-small LED elements for lighting, displays, etc. Areas that are continuously attracting attention in this research include electrodes that can apply power to ultra-small LED elements, electrode arrangements for purposes of use and to reduce the space occupied by the electrodes, and methods of mounting ultra-small LEDs on the arranged electrodes.

[0005] Among these, the method of mounting the micro LED element on the arranged electrode still has a drawback in that it is very difficult to arrange and mount the micro LED element on the electrode as intended due to the size constraint of the micro LED element. This is because the micro LED element is nano-scale or micro-scale, and it is not possible to arrange and mount it on the intended electrode area one by one manually.

[0006] Recently, the demand for nano-scale ultra-small LED elements is gradually increasing, and for this reason, there are attempts to manufacture nano-scale GaN-based compound semiconductors or InGaN-based compound semiconductors in rod form, but the large particle size of the nanorods themselves significantly reduces the dispersion stability in the solution.To date, there has been no introduction of technology that can improve the dispersion stability of semiconductor nanorods in solution. Summary of the Invention [Problem to be solved by the invention]

[0007] An object of one embodiment is to provide an ink composition that has high viscosity at room temperature to impart sedimentation stability to semiconductor nanorods, and at the same time has low viscosity at high temperatures to provide excellent inkjetting properties.

[0008] Another object of an embodiment is to provide a film produced using the ink composition.

[0009] It is an object of another embodiment to provide a display device comprising said film. [Means for solving the problem]

[0010] One embodiment provides an ink composition comprising: (A) semiconductor nanorods; and (B) a solvent containing at least one diol compound, the ink composition having a viscosity of 50 cps or more at 20°C to 25°C and 20 cps or less at 35°C to 65°C.

[0011] The diol-based compound may be represented by the following Chemical Formula 1.

[0012] [ka]

[0013] In the above Chemical Formula 1, R 1 and R 2 each independently represents a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group, L 1 is a substituted or unsubstituted C1 to C20 alkylene group.

[0014] The diol-based compound may include at least one of compounds represented by the following Formulas 1-1 to 1-5.

[0015] [ka]

[0016] The solvent may further include a compound represented by the following Formula 2 or 3:

[0017] [ka]

[0018] In the above Chemical Formula 2 and Chemical Formula 3, R 3 ~R 5 are each independently a substituted or unsubstituted C1 to C20 alkyl group, R 6 ~R 8 are each independently a substituted or unsubstituted C1 to C20 alkoxy group.

[0019] In the above formula 2, R 3 ~R 5 may each independently be a C1 to C20 alkyl group unsubstituted or substituted with a C2 to C10 alkenyl group.

[0020] In the above formula 3, R 6 ~R 8 may each independently be a C1 to C20 alkoxy group unsubstituted or substituted with a C2 to C10 alkenyl group.

[0021] The compound represented by the formula 2 may include at least one selected from the group consisting of the following formulas 2-1 and 2-2.

[0022] [ka]

[0023] The compound represented by the formula 3 may include at least one selected from the group consisting of compounds represented by the following formulas 3-1 and 3-2.

[0024] [ka]

[0025] The compound represented by Formula 2 or Formula 3 may be included in a smaller amount than the compound having a diol structure.

[0026] The solvent may further include a compound represented by the following Formula 4:

[0027] [ka]

[0028] In the above Chemical Formula 4, R 9 ~R 11 are each independently a hydrogen atom or a C1 to C10 alkyl group, R 12 is a hydrogen atom or -C(=O)R 13 (R 13 is a C1 to C10 alkyl group, L 16 and L 17 each independently represents a substituted or unsubstituted C1 to C20 alkylene group or a substituted or unsubstituted C6 to C20 arylene group, L 18 is *-O-*, *-S-* or *-NH-*.

[0029] The diol-based compound and the compound represented by Formula 4 may be included in a weight ratio of 3:7 to 8:2.

[0030] The semiconductor nanorods can have a diameter of 300 nm to 900 nm.

[0031] The semiconductor nanorods may have a length of 3.5 μm to 5 μm.

[0032] The semiconductor nanorods can include a GaN-based compound, an InGaN-based compound, or a combination thereof.

[0033] The semiconductor nanorods may have a surface coated with a metal oxide.

[0034] The metal oxide may include alumina, silica, or a combination thereof.

[0035] The semiconductor nanorods may be included in an amount of 0.01% by weight to 10% by weight based on the total amount of the ink composition.

[0036] The ink composition may further include a polymerization inhibitor; malonic acid; 3-amino-1,2-propanediol; a silane coupling agent; a leveling agent; a fluorosurfactant; or a combination thereof.

[0037] The ink composition may be an ink composition for an electrophoretic device.

[0038] Another embodiment provides a film produced using the ink composition.

[0039] Yet another embodiment provides a display device including the film.

[0040] Other specific aspects of the present invention are included in the following detailed description. Effect of the Invention

[0041] According to one embodiment, it is possible to provide an ink composition that simultaneously has excellent dielectrophoretic properties and dispersion stability of semiconductor nanorods. [Brief description of the drawings]

[0042] [Figure 1] 2 is an example of a cross-sectional view of a semiconductor nanorod used in an ink composition according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail, but they are given by way of example only and are not intended to limit the present invention, which is defined only by the scope of the claims set forth below.

[0044] Unless otherwise specified in this specification, an "alkyl group" means a C1 to C20 alkyl group, an "alkenyl group" means a C2 to C20 alkenyl group, a "cycloalkenyl group" means a C3 to C20 cycloalkenyl group, a "heterocycloalkenyl group" means a C3 to C20 heterocycloalkenyl group, an "aryl group" means a C6 to C20 aryl group, an "arylalkyl group" means a C6 to C20 arylalkyl group, an "alkylene group" means a C1 to C20 alkylene group, an "arylene group" means a C6 to C20 arylene group, an "alkylarylene group" means a C6 to C20 alkylarylene group, a "heteroarylene group" means a C3 to C20 heteroarylene group, and an "alkoxyylene group" means a C1 to C20 alkoxyylene group.

[0045] Unless otherwise specified in this specification, "substituted" means that at least one hydrogen atom is substituted with a substituent selected from the group consisting of a halogen atom (F, Cl, Br, I), a hydroxy group, a C1-C20 alkoxy group, a nitro group, a cyano group, an amine group, an imino group, an azide group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, an ether group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, phosphoric acid or a salt thereof, a C1-C20 alkyl group, a C2-C20 alkenyl group, a C2-C20 alkynyl group, a C6-C20 aryl group, a C3-C20 cycloalkyl group, a C3-C20 cycloalkenyl group, a C3-C20 cycloalkynyl group, a C2-C20 heterocycloalkyl group, a C2-C20 heterocycloalkenyl group, a C2-C20 heterocycloalkynyl group, a C3-C20 heteroaryl group, or a combination thereof.

[0046] In addition, unless otherwise specified in this specification, "hetero" means that at least one heteroatom selected from the group consisting of N, O, S and P is included in the chemical formula.

[0047] In addition, unless otherwise specified in this specification, "(meth)acrylate" means that both "acrylate" and "methacrylate" are possible, and "(meth)acrylic" means that both "acrylic" and "methacrylic" are possible.

[0048] Unless otherwise specified herein, "combination" means blending or copolymerization.

[0049] Unless otherwise defined in the chemical formulas herein, when no chemical bond is drawn at a position where a chemical bond should be drawn, this means that a hydrogen atom is bonded at that position.

[0050] As used herein, the term "semiconductor nanorod" refers to a semiconductor having a rod-like shape with a nano-sized diameter.

[0051] Also, unless otherwise stated in this specification, "*" means a moiety linked to the same or different atom or chemical formula.

[0052] The ink composition according to one embodiment includes (A) semiconductor nanorods; and (B) a solvent containing at least one diol compound, and has a viscosity of 50 cps or more at 20°C to 25°C and 20 cps or less at 35°C to 65°C.

[0053] Recently, various concepts that can improve the energy efficiency and prevent efficiency drops of existing LEDs such as micro LEDs and mini LEDs are being actively researched. Among them, alignment (electrophoresis) of InGaN nanorod LEDs using an electric field is attracting attention as a method that can dramatically reduce the complicated and high process costs of micro LEDs and mini LEDs.

[0054] In order to coat a substrate for electrophoresis of semiconductor nanorods, a semiconductor nanorod dispersion must be inkjetted or slit coated. In particular, for large-area coating and panel production, the semiconductor nanorods must be uniformly applied, and this requires dispersion stability of the semiconductor nanorod solution. Also, a high dielectrophoretic coefficient is an essential parameter for increasing the luminous efficiency of LEDs. The present invention relates to a novel ink composition for inkjet printing that can simultaneously achieve dispersion stability and high dielectrophoretic coefficient of semiconductor nanorods.

[0055] Each component will be specifically described below.

[0056] (A) Semiconductor nanorods The semiconductor nanorods may include a GaN-based compound, an InGaN-based compound, or a combination thereof, and may have a surface coated with a metal oxide.

[0057] In general, about 3 hours is required for the dispersion stability of the semiconductor nanorod ink solution (semiconductor nanorods + solvent), which is not enough time for a large-area inkjet process. Therefore, the inventors have conducted a lot of trial and error research and have found that the surface of the semiconductor nanorod is coated with a metal oxide including alumina, silica, or a combination of these to form an insulating film (Al 2 O 3 Or SiO x By forming such a copolymer, it is possible to maximize the compatibility with the solvent described below.

[0058] For example, the insulating film coated with the metal oxide may have a thickness of 40 nm to 60 nm.

[0059] The semiconductor nanorod may include an n-type confinement layer and a p-type confinement layer, and a multi quantum well active region (MQW active region) may be located between the n-type confinement layer and the p-type confinement layer (see FIG. 1). For example, the semiconductor nanorods can have a diameter of 300 nm to 900 nm, such as 600 nm to 700 nm.

[0060] For example, the semiconductor nanorods can have a length of 3.5 μm to 5 μm.

[0061] For example, when the semiconductor nanorods include an alumina insulating film, the thickness of the semiconductor nanorods is 5 g / cm 3 ~6g / cm 3 The density of the powder may be 0.01 to 0.01.

[0062] For example, the semiconductor nanorods may be 1×10 -13 g~1x10 -11 It may have a mass of g.

[0063] When the semiconductor nanorods have the above diameter, length, density and type, the metal oxide can be easily coated on the surface, and the dispersion stability of the semiconductor nanorods can be maximized.

[0064] The semiconductor nanorods may be included in an amount of 0.01 wt % to 10 wt %, for example, 0.02 wt % to 8 wt %, for example, 0.03 wt % to 5 wt %, based on the total amount of the ink composition. When the semiconductor nanorods are included within this range, they have good dispersibility in the ink, and the produced pattern can have excellent brightness.

[0065] (B) Solvent The ink composition according to one embodiment includes a solvent.

[0066] Organic solvents such as propylene glycol monomethyl ether acetate (PEGMEA), gamma-butyrolactone (GBL), polyethylene glycol methyl ether (PGME), ethyl acetate, and isopropyl alcohol (IPA) used in existing display and electronic materials have low viscosities, which cause excessively fast sedimentation of dense inorganic nanorod particles and poor dielectrophoretic properties. Therefore, in order to develop NED-Ink, it is preferable to use a solvent that can provide sedimentation stability to nanorods. However, if the viscosity of the solvent is simply high, there is a problem that the ink cannot be ejected during inkjetting. To improve this, the present inventors have developed a solvent that has high viscosity at room temperature by increasing the temperature during inkjetting, and at the same time, has low viscosity at temperatures higher than room temperature, and have finally completed an ink composition containing a solvent having the above properties.

[0067] Specifically, in one embodiment, a compound having a diol structure with hydrogen bonds is introduced into the solvent, thereby increasing the viscosity of the ink composition at room temperature and decreasing the viscosity at high temperatures higher than room temperature. However, when a compound having a structure other than a diol structure, which has hydrogen bonds but has the above-mentioned hydrogen bonds, for example a multiol structure having three or more hydroxyl groups, is introduced into the solvent, the dielectric constant is too high and the dielectrophoretic properties are deteriorated, so that it is not suitable for use as a solvent in the ink composition according to one embodiment.

[0068] When the viscosity is high at room temperature, dispersion stability can be ensured for 10 hours or more. In order to ensure dispersion stability for a long period of time, it is preferable to have as high a viscosity as possible at room temperature, specifically, a viscosity of 50 cps or more at 20°C to 25°C (e.g., 50 cps to 2,000 cps).

[0069] More specifically, in order to ensure inkjetting properties, the viscosity of the solvent at high temperatures (35°C to 65°C, for example, 40°C to 50°C) must be 20 cps or less (for example, 1 cps to 20 cps). In order to ensure a solvent that has a large change in viscosity between room temperature (for example, 20°C to 25°C) and high temperature, a diol-based compound represented by the following Chemical Formula 1 can be used alone or in combination to control the dielectric constant and viscosity.

[0070] [ka]

[0071] In the above Chemical Formula 1, R 1 and R 2 each independently represents a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group, L 1 is a substituted or unsubstituted C1 to C20 alkylene group.

[0072] For example, the diol-based compound may include at least one of the compounds represented by the following Formulae 1-1 to 1-5, but is not necessarily limited thereto.

[0073] [ka]

[0074] For example, the diol-based compound may be included in an amount of 20% by weight to 85% by weight, for example, 30% by weight to 80% by weight, based on the total amount of the ink composition. When the content of the compound having a diol structure is within this range, it is possible to improve the dispersion stability of the semiconductor nanorods while maintaining an appropriate dielectric constant.

[0075] For example, the solvent may further include at least one of compounds represented by the following Formula 2, Formula 3, and Formula 4.

[0076] [ka]

[0077] In the above Chemical Formula 2 to Chemical Formula 4, R 3 ~R 5 are each independently a substituted or unsubstituted C1 to C20 alkyl group, R 6 ~R 8 are each independently a substituted or unsubstituted C1 to C20 alkoxy group.

[0078] R 9 ~R 11 are each independently a hydrogen atom or a C1 to C10 alkyl group, R 12 is a hydrogen atom or -C(=O)R 13 (R 13 is a C1 to C10 alkyl group, L 16 and L 17 each independently represents a substituted or unsubstituted C1 to C20 alkylene group or a substituted or unsubstituted C6 to C20 arylene group, L 18 is *-O-*, *-S-* or *-NH-*.

[0079] For example, in Formula 2, R 3 ~R 5 may each independently be a C1 to C20 alkyl group unsubstituted or substituted with a C2 to C10 alkenyl group.

[0080] For example, in Formula 3, R 6 ~R 8 may each independently be a C1 to C20 alkoxy group unsubstituted or substituted with a C2 to C10 alkenyl group.

[0081] For example, the compound represented by Chemical Formula 2 may include at least one selected from the group consisting of the following Chemical Formula 2-1 and Chemical Formula 2-2, but is not necessarily limited thereto.

[0082] [ka]

[0083] For example, the compound represented by Chemical Formula 3 may include at least one selected from the group consisting of compounds represented by Chemical Formula 3-1 and Chemical Formula 3-2 below.

[0084] [ka]

[0085] For example, the compound represented by Chemical Formula 4 may be citric acid.

[0086] For example, the compound represented by Chemical Formula 4 may be represented by any one of Chemical Formulas 4-1 to 4-6 below, but is not necessarily limited thereto.

[0087] [ka]

[0088] [ka]

[0089] For example, the compound represented by Formula 2 or Formula 3 may be included in a smaller amount than the diol-based compound.

[0090] For example, the diol-based compound and the compound represented by Chemical Formula 4 may be included in a weight ratio of 3:7 to 8:2.

[0091] Conventional organic solvents such as propylene glycol monomethyl ether acetate (PEGMEA), gamma-butyrolactone (GBL), polyethylene glycol methyl ether (PGME), ethyl acetate, and isopropyl alcohol (IPA) all have low viscosities, and therefore there is a limit to the improvement of the sedimentation stability of high density semiconductor nanorods. However, when at least one of the compounds represented by Formulae 2 to 4 is additionally used together with the diol-based compound, it is easier to control the viscosity of the ink composition at room temperature and at temperatures higher than the room temperature, and the sedimentation stability of the semiconductor nanorods can be significantly improved. In addition, the dielectrophoretic coefficient can be significantly improved since the ink composition has an appropriate dielectric constant value.

[0092] The solvent may be included in an amount of 15% by weight to 99.9% by weight, for example, 15% by weight to 99.8% by weight, for example, 20% by weight to 99.7% by weight, based on the total amount of the ink composition.

[0093] Polymerizable Monomer The ink composition according to an embodiment may further include a polymerizable monomer having a terminal carbon-carbon double bond.

[0094] The polymerizable monomer may be a mixture of monomers or oligomers that are generally used in conventional curable compositions.

[0095] For example, the polymerizable monomer may be a polymerizable monomer having at least one functional group represented by the following formula 5 at its terminal.

[0096] [ka]

[0097] In the above Chemical Formula 5, R 14 is a hydrogen atom or a substituted or unsubstituted C1 to C20 alkyl group.

[0098] Since the polymerizable monomer contains a carbon-carbon double bond at an end, specifically, at least one functional group represented by the chemical formula 5, it can form a crosslinked structure with the semiconductor nanorods, thereby further improving the dispersion stability of the semiconductor nanorods.

[0099] For example, examples of polymerizable monomers having at least one functional group represented by Chemical Formula 5 at their terminals include ethylene glycol diacrylate, triethylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol diacrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, pentaerythritol hexaacrylate, bisphenol A diacrylate, trimethylolpropane triacrylate, novolac epoxy acrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, multifunctional epoxy (meth)acrylate, multifunctional urethane (meth)acrylate, and KAYARAD manufactured by Nippon Kagaku Co., Ltd. Examples of suitable DPCA-20, KAYARAD DPCA-30, KAYARAD DPCA-60, KAYARAD DPCA-120, KAYARAD DPEA-12, or combinations thereof, but are not limited to these.

[0100] Polymerization initiator The ink composition according to an embodiment may further include a polymerization initiator, for example, a photopolymerization initiator, a thermal polymerization initiator, or a combination thereof.

[0101] The photopolymerization initiator may be an initiator commonly used in the curable composition, such as, for example, an acetophenone-based compound, a benzophenone-based compound, a thioxanthone-based compound, a benzoin-based compound, a triazine-based compound, an oxime-based compound, or an aminoketone-based compound, but is not necessarily limited thereto.

[0102] Examples of the acetophenone-based compounds include 2,2'-diethoxyacetophenone, 2,2'-dibutoxyacetophenone, 2-hydroxy-2-methylpropiophenone, pt-butyltrichloroacetophenone, pt-butyldichloroacetophenone, 4-chloroacetophenone, 2,2'-dichloro-4-phenoxyacetophenone, 2-methyl-1-(4-(methylthio)phenyl)-2-morpholinopropan-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one.

[0103] Examples of the benzophenone-based compounds include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-dimethylaminobenzophenone, 4,4'-dichlorobenzophenone, and 3,3'-dimethyl-2-methoxybenzophenone.

[0104] Examples of the thioxanthone compounds include thioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone.

[0105] Examples of the benzoin-based compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and benzyl dimethyl ketal.

[0106] Examples of the triazine-based compound include 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(3',4'-dimethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4'-methoxynaphthyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, azine, 2-biphenyl-4,6-bis(trichloromethyl)-s-triazine, bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxynaphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-4-bis(trichloromethyl)-6-piperonyl-s-triazine, 2-4-bis(trichloromethyl)-6-(4-methoxystyryl)-s-triazine, and the like.

[0107] Examples of the oxime-based compound include O-acyloxime-based compounds, 2-(O-benzoyloxime)-1-[4-(phenylthio)phenyl]-1,2-octanedione, 1-(O-acetyloxime)-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone, and O-ethoxycarbonyl-α-oxyamino-1-phenylpropan-1-one. Specific examples of the O-acyloxime compounds include 1,2-octanedione, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 1-(4-phenylsulfanylphenyl)-butan-1,2-dione-2-oxime-O-benzoate, 1-(4-phenylsulfanylphenyl)-octane-1,2-dione-2-oxime-O-benzoate, 1-(4-phenylsulfanylphenyl)-octan-1-one oxime-O-acetate, and 1-(4-phenylsulfanylphenyl)-butan-1-one oxime-O-acetate.

[0108] Examples of the aminoketone compounds include 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1.

[0109] In addition to the above compounds, the photopolymerization initiator may be a carbazole-based compound, a diketone compound, a sulfonium borate-based compound, a diazo-based compound, an imidazole-based compound, a non-imidazole-based compound, or the like.

[0110] The photoinitiator may be used in conjunction with a photosensitizer, which absorbs light, becomes suspended in water, and then transfers the energy to initiate a chemical reaction.

[0111] Examples of the photosensitizer include tetraethylene glycol bis-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol tetrakis-3-mercaptopropionate.

[0112] Examples of the thermal polymerization initiator include peroxides, specifically benzoyl peroxide, dibenzoyl peroxide, lauryl peroxide, dilauryl peroxide, di-tert-butyl peroxide, cyclohexane peroxide, methyl ethyl ketone peroxide, hydroperoxides (e.g., tert-butyl hydroperoxide, cumene hydroperoxide), dicyclohexyl peroxydicarbonate, 2,2-azo-bis(isobutyronitrile), t-butyl perbenzoate, and 2,2'-azobis-2-methylpropionitrile, but are not limited thereto. Any initiators widely known in the art may be used.

[0113] The polymerization initiator may be contained in an amount of 1 wt % to 5 wt %, for example, 2 wt % to 4 wt %, based on the total amount of solids constituting the ink composition. When the polymerization initiator is contained within the above range, curing occurs sufficiently upon exposure or thermal curing, and excellent reliability can be obtained.

[0114] Other additives According to an embodiment, the ink composition may further include a polymerization inhibitor including a hydroquinone-based compound, a catechol-based compound, or a combination thereof. By further including the hydroquinone-based compound, the catechol-based compound, or a combination thereof, the ink composition according to an embodiment may prevent room temperature crosslinking during exposure after printing (coating) of the ink composition.

[0115] For example, the hydroquinone-based compound, the catechol-based compound, or a combination thereof may include, but is not necessarily limited to, hydroquinone, methylhydroquinone, methoxyhydroquinone, t-butylhydroquinone, 2,5-di-t-butylhydroquinone, 2,5-bis(1,1-dimethylbutyl)hydroquinone, 2,5-bis(1,1,3,3-tetramethylbutyl)hydroquinone, catechol, t-butylcatechol, 4-methoxyphenol, pyrogallol, 2,6-di-t-butyl-4-methylphenol, 2-naphthol, tris(N-hydroxy-N-nitrosophenylaminato-O,O')aluminium, or a combination thereof.

[0116] The hydroquinone-based compound, the catechol-based compound, or a combination thereof may be used in the form of a dispersion, and the polymerization inhibitor in the form of a dispersion may be included in an amount of 0.001% by weight to 1% by weight, for example, 0.01% by weight to 0.1% by weight, based on the total amount of the ink composition. When the stabilizer is included within the above range, the problems caused by aging at room temperature can be solved, and at the same time, the sensitivity reduction and surface peeling phenomenon can be prevented.

[0117] In addition to the polymerization inhibitor, the ink composition according to an embodiment may further include malonic acid; 3-amino-1,2-propanediol; a silane-based coupling agent; a leveling agent; a fluorine-based surfactant; or a combination thereof.

[0118] For example, the ink composition for electrophoretic devices may further contain a silane coupling agent having a reactive substituent such as a vinyl group, a carboxyl group, a methacryloxy group, an isocyanate group, or an epoxy group in order to improve adhesion to a substrate.

[0119] Examples of the silane coupling agent include trimethoxysilylbenzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane, γ-isocyanatepropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-epoxycyclohexylethyltrimethoxysilane, and the like. These can be used alone or in combination of two or more kinds.

[0120] The silane coupling agent may be contained in an amount of 0.01 to 10 parts by weight relative to 100 parts by weight of the ink composition. When the silane coupling agent is contained within the above range, the ink composition has excellent adhesion, storage stability, and the like.

[0121] Furthermore, the ink composition may further contain a surfactant, such as a fluorine-based surfactant, in order to improve coating properties and prevent the formation of defects, if necessary.

[0122] Examples of the fluorine-based surfactant include BM-1000 (registered trademark) and BM-1100 (registered trademark) manufactured by BM Chemie; Megafac F142D (registered trademark), Megafac F172 (registered trademark), Megafac F173 (registered trademark), Megafac F183 (registered trademark) manufactured by Dainippon Ink and Chemicals, Inc.; Fluorad FC-135 (registered trademark), Fluorad FC-170C (registered trademark), Fluorad FC-430 (registered trademark), Fluorad FC-431 (registered trademark) manufactured by Sumitomo 3M Limited; and Surflon S manufactured by Asahi Glass Co., Ltd. Fluorine-based surfactants commercially available under the names of SURFRON S-112 (registered trademark), SURFRON S-113 (registered trademark), SURFRON S-131 (registered trademark), SURFRON S-141 (registered trademark), SURFRON S-145 (registered trademark), etc. manufactured by Toray Silicon Co., Ltd.; SH-28PA (registered trademark), SH-190 (registered trademark), SH-193 (registered trademark), SZ-6032 (registered trademark), SF-8428 (registered trademark), etc. manufactured by Toray Silicon Co., Ltd.; F-482, F-484, F-478, F-554, etc. manufactured by DIC Corporation can be used.

[0123] The fluorosurfactant can be used in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the ink composition. When the fluorosurfactant is within this range, coating uniformity is ensured, stains do not occur, and wetting to glass substrates is excellent.

[0124] In addition, the ink composition may further contain a certain amount of other additives such as an antioxidant and a stabilizer within a range that does not impair the physical properties.

[0125] Another embodiment provides a film utilizing the ink composition.

[0126] Yet another embodiment provides a display device including the membrane, for example the display device may be an electrophoretic device.

[0127] [Example] Hereinafter, preferred embodiments of the present invention will be described, however, the following embodiment is merely one preferred embodiment of the present invention and the present invention is not limited to the following embodiment.

[0128] (Production of Ink Composition) Examples 1 to 6 and Comparative Examples 1 to 6 A 4-inch GaN wafer with nano rod patterning is reacted with 40 ml of stearic acid (1.5 mM) at room temperature for 24 hours. After the reaction, the wafer is immersed in 50 ml of acetone for 5 minutes to remove excess stearic acid, and an additional 40 ml of acetone is used to rinse the wafer surface. The washed wafer is placed in a 27 kW bath type sonicator with 35 ml of GBL, and the rods are separated from the wafer surface using sonication for 5 minutes. The separated rods are placed in a FALCON tube for centrifuges, and 10 ml of GBL is added to further rinse the rods on the bath surface. After centrifuging at 4000 rpm for 10 minutes, discard the supernatant and redisperse the precipitate in acetone (40 ml) and filter out foreign matter using a 10 μm mesh filter. After additional centrifugation (4000 rpm, 10 minutes), the precipitate is dried in a drying oven (100°C for 1 hour) and then weighed. The precipitate is dispersed in a composition having the composition shown in Tables 1 and 2 below at 0.05 w / w% to prepare an ink composition.

[0129] [Table 1]

[0130] [Table 2]

[0131] Solvent Type (B-1) 2,4-Diethyl-1,5-pentanediol (B-2) 2-Ethyl-1,3-Hexanediol (B-3) 3-methyl-1,5-pentanediol (B-4) 1,5-pentanediol (B-5) Propanediol (B-6) Triethyl citrate (B-7) Triallyl isocyanurate (B-8) polyethylene glycol (B-9) propylene glycol (B-10) 2-Methyl-2,4-pentanediol (B-11) PGMEA (B-12) GBL Evaluation: Viscosity, dielectric constant, dispersion stability and dielectrophoretic properties of the ink composition The viscosity (25° C., 50° C.), dielectric constant, dispersion stability and dielectrophoretic properties of the ink compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were measured, and the results are shown in Table 3 below.

[0132] The viscosity of the solvent was measured at temperatures of 25° C. and 50° C. using a rheometer (Haake) by loading 2 ml of the composition.

[0133] The dielectric constant was measured at 25° C. using a liquid dielectric constant measuring device (Furuto, Model 871) by placing 40 ml of the solution in a conical tube.

[0134] The dispersion stability was measured by placing 10 ml of the composition in a test tube having a diameter of 1 cm and a height of 13 cm, and measuring the time it took for precipitation to occur at the bottom at room temperature.

[0135] The dielectrophoretic characteristics were measured as follows.

[0136] First, 500μl of nanorod ink composition was applied using Thin-film Gold basic interdigitated linear electrodes (ED-cIDE4-Au, Micrux), and then an electric field (25KHz, ±30v) was applied and left for 1 minute. After this, the solvent was dried using a hot plate, and the number of aligned particles (ea) and non-aligned particles (ea) in the center between the electrodes were checked using a microscope to evaluate the dielectrophoretic properties.

[0137] [Table 3]

[0138] (ND: Not Detected) As shown in Table 3, in the case of Examples 1 to 6, the viscosity at 25°C is higher than that of Comparative Examples 1 to 6, but the viscosity at 50°C is lower. Therefore, the dielectric constant is in an appropriate range, and the dispersion stability and dielectrophoretic properties are all excellent, and the compositions are suitable for producing large-area coatings and panels.

[0139] The present invention is not limited to the above-mentioned embodiments, and can be manufactured in various different forms, and a person having ordinary skill in the art to which the present invention belongs can understand that the present invention can be embodied in other specific forms without changing the technical concept or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting.

Claims

1. (A) a semiconductor nanorod; and (B) A solvent containing at least one diol compound Including, It has a viscosity of 50 cps or more over the entire temperature range of 20° C. to 25° C. and a viscosity of 20 cps or less over the entire temperature range of 35° C. to 65° C., The diol-based compound is represented by the following Chemical Formula 1. 【Chemistry 1】 (In the above Chemical Formula 1, R 1 and R 2 are each independently a hydrogen atom, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, or a substituted or unsubstituted C6 to C20 aryl group; L 1 is a substituted or unsubstituted C1 to C20 alkylene group.

2. The ink composition according to claim 1, wherein the solvent is contained in an amount of 15% by weight to 99.9% by weight based on the total amount of the ink composition.

3. The ink composition according to claim 1, wherein the diol-based compound includes at least one of compounds represented by the following Formulas 1-1 to 1-5. 【Chemistry 2】

4. The ink composition of claim 1 , wherein the solvent further comprises a compound represented by the following Formula 2 or 3: 【Chemistry 3】 (In the above Chemical Formula 2 and Chemical Formula 3, R ３ ~R ５ are each independently a C1 to C20 alkyl group unsubstituted or substituted with a C2 to C10 alkenyl group, R ６ ~R ８ are each independently a C1 to C20 alkoxy group unsubstituted or substituted with a C2 to C10 alkenyl group.

5. The ink composition according to claim 4, wherein the compound represented by Chemical Formula 2 or Chemical Formula 3 includes at least one selected from the compounds represented by Chemical Formula 2-1, Chemical Formula 2-2, Chemical Formula 3-1, and Chemical Formula 3-2: 【Chemistry 4】 【Chemistry 5】

6. The ink composition according to claim 4 , wherein the compound represented by Formula 2 or Formula 3 is contained in an amount less than that of the diol-based compound.

7. The ink composition of claim 1 , wherein the solvent further comprises a compound represented by the following formula 4: 【Chemistry 6】 (In the above Chemical Formula 4, R ９ ~R １１ are each independently a hydrogen atom or a C1 to C10 alkyl group, R １２ is a hydrogen atom or *-C(=O)R １３ (R １３ is a C1 to C10 alkyl group; L １６ and L １７ are each independently a substituted or unsubstituted C1 to C20 alkylene group or a substituted or unsubstituted C6 to C20 arylene group, L １８ is *-O-*, *-S-* or *-NH-*.

8. The ink composition according to claim 7, wherein the diol-based compound and the compound represented by Formula 4 are contained in a weight ratio of 3:7 to 8:

2.

9. The ink composition of claim 1, wherein the semiconductor nanorods have a diameter of 300 nm to 900 nm.

10. The ink composition of claim 1 , wherein the semiconductor nanorods have a length of 3.5 μm to 5 μm.

11. The ink composition of claim 1 , wherein the semiconductor nanorods comprise a GaN-based compound, an InGaN-based compound, or a combination thereof.

12. The ink composition according to claim 1 , wherein the semiconductor nanorods have a surface coated with a metal oxide.

13. The ink composition of claim 12 , wherein the metal oxide comprises alumina, silica, or a combination thereof.

14. The ink composition according to claim 1, wherein the semiconductor nanorods are contained in an amount of 0.01% by weight to 10% by weight based on the total amount of the ink composition.

15. The ink composition of claim 1, further comprising: a polymerization inhibitor; malonic acid; 3-amino-1,2-propanediol; a silane coupling agent; a leveling agent; a fluorosurfactant; or a combination thereof.

16. The ink composition according to claim 1 , wherein the ink composition is an ink composition for an electrophoretic device.

17. A method for producing a film, comprising utilizing the ink composition according to any one of claims 1 to 16.

18. A method for manufacturing a display device, comprising steps of the method for manufacturing the film described in claim 17.

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