CN119654581A

CN119654581A - Ink composition, method for producing ink composition, and method for producing color filter

Info

Publication number: CN119654581A
Application number: CN202380060513.9A
Authority: CN
Inventors: 野岛义弘; 青木伸司; 鸢岛一也
Original assignee: Shin Etsu Chemical Co Ltd
Current assignee: Shin Etsu Chemical Co Ltd
Priority date: 2022-08-23
Filing date: 2023-08-08
Publication date: 2025-03-18
Also published as: TW202428844A; WO2024043081A1

Abstract

本发明为一种油墨组合物，其为包含量子点的油墨组合物，其特征在于，其包含使所述量子点与倍半硅氧烷共聚而成的倍半硅氧烷聚合物、或使所述量子点及烷氧基硅烷共聚而成的倍半硅氧烷聚合物。由此，提供一种能够使量子点在高浓度下分散而不凝聚从而包含可靠性高的量子点的油墨组合物。The present invention is an ink composition, which is an ink composition containing quantum dots, characterized in that it contains a silsesquioxane polymer obtained by copolymerizing the quantum dots with silsesquioxane, or a silsesquioxane polymer obtained by copolymerizing the quantum dots with alkoxysilane. Thus, an ink composition containing quantum dots with high reliability that can disperse the quantum dots at a high concentration without agglomeration is provided.

Description

Ink composition, method for producing ink composition, and method for producing color filter

Technical Field

The invention relates to an ink composition, a method for preparing the ink composition and a method for manufacturing a color filter.

Background

Semiconductor crystal particles having a particle size of nanometer size are called quantum dots, and excitons generated by light absorption are trapped in a nanometer-sized region, whereby the energy level of the semiconductor crystal particles is dispersed, and the band gap thereof varies according to the particle size. Due to these effects, the quantum dots emit fluorescence with higher brightness and higher efficiency than general phosphors, and emit light clearly.

Further, since the band gap is a characteristic that varies depending on the particle size, it has a characteristic that the emission wavelength can be controlled, and thus, it is expected to be used as a wavelength conversion material for solid-state lighting or a display. For example, quantum dots can be used as a wavelength conversion material for a display, whereby a wider color gamut and lower power consumption can be achieved than conventional phosphor materials.

As a method of mounting quantum dots as a wavelength conversion material, there is proposed a method of dispersing quantum dots in a resin material, and laminating the resin material containing quantum dots with a transparent film, thereby assembling the quantum dots as a wavelength conversion film to a backlight unit (patent document 1). Further, it has been proposed that quantum dots absorb blue monochromatic light from a backlight unit and emit red or green light by using the quantum dots as a color filter material, and the quantum dots function as a color filter and a wavelength conversion material, thereby being suitable for an image element excellent in high efficiency and color reproducibility (patent document 2).

Attention has been paid to a micro LED display in which the backlight unit is replaced with a micro-sized LED array. In a micro LED display, a color filter is formed on a micro-sized LED.

In recent years, miniaturization of the LED array size has progressed, and finer patterns than those of conventional quantum dots have been sought. In addition, in color filter applications, it is also necessary to increase the light absorption amount of the color filter in order to suppress leakage of blue monochromatic light, which is excitation light, from the color filter. In order to increase the light absorption amount of the color filter, it is necessary to increase the quantum dot concentration.

As a method of forming a quantum dot color filter on an LED array, a lithography process using a photosensitive material has been proposed (patent document 3). However, since the uncured portion is wasted in the photolithography, the raw material is largely consumed, and the number of manufacturing steps such as baking, exposure, and development is large. Therefore, in recent years, research on an inkjet system has been conducted. In the case of the ink jet method, the loss of the raw material is small, only ejection and solidification are performed, the manufacturing process is simple, and the method is also competitive in terms of cost.

Prior art literature

Patent literature

Patent document 1 Japanese patent application laid-open No. 2013-544018

Patent document 2 Japanese patent application laid-open No. 2017-021322

Patent document 3 Japanese patent laid-open No. 2021-089347

Patent document 4 Japanese patent application laid-open No. 2016-518468

Patent document 5 Japanese patent application laid-open No. 2013-505346

Patent document 6 Japanese patent No. 6283092

Non-patent literature

Non-patent document 1:Journal of Photopolymer Science and Technology,Vol 23,2010,p115-119

Disclosure of Invention

First, the technical problem to be solved

However, since ink is discharged from a relatively thin nozzle, the nozzle diameter is also reduced in order to form a fine pattern of 100 μm or less, which is required in applications such as micro LEDs, and there is a large limitation on the characteristics of ink in order to ensure stable discharge and reproducibility of the pattern. For example, there are problems such as viscosity of ink, evaporation rate of ink, concentration of quantum dots as solid components contained in ink, aggregation or sedimentation of quantum dots in a resin solution, and the like, and if these are not within a proper range satisfying the device and discharge conditions, clogging of a nozzle portion or an ink supply line is likely to occur, or if discharge is continued, variation or deviation in discharge characteristics occurs, and characteristic unevenness between pixels is also caused.

Resin materials such as acrylic resin and silicone resin having a polarity generally have poor compatibility with hydrophobic quantum dots and cause aggregation because they are dispersed in solvents having a polarity such as PGMEA and PGME, which is also a serious problem. Agglomeration can cause blockage in the inkjet nozzles or supply lines, a process being a major problem.

In addition, in the inkjet method, in order to cope with miniaturization, coating by a nozzle having a small diameter is attempted, but if the nozzle is made smaller, problems such as clogging or discharge instability occur. Further, although a nonpolar solvent is used because the quantum dot is hydrophobic, a nonpolar solvent such as toluene or hexane which is generally used has a low boiling point and is easily evaporated, and thus nozzle clogging due to evaporation of the solvent at the tip of the nozzle is easily caused. In particular, the higher the quantum dot concentration, the more pronounced this phenomenon.

If the viscosity of the ink is high, there are problems such as clogging of the nozzle portion and ink supply line, and if the ink is continuously discharged, there are problems such as variation or variation in discharge characteristics, and variation in characteristics among pixels, and in order to form a stable pattern, a low-viscosity ink is required, and if the content of the curable resin or quantum dots in the ink composition is high, the viscosity of the ink composition is generally high, and thus, defects in the process are caused.

Further, quantum dots in the patterned resin composition are present in the resin material, and thus, unlike the environment in a solution, separation of a ligand and the like are liable to occur, and deterioration of light emission characteristics thereof also becomes a problem due to change with time.

In order to solve such problems, various methods such as surface coating (patent document 4) or encapsulation (patent document 5) of quantum dots and polyhedral oligomeric silsesquioxane ligand (patent document 6) have been attempted to improve dispersibility in polar solvents or resin materials and to improve stability, but it is difficult to achieve both inhibition of aggregation and stability in resin materials, particularly at high concentrations of quantum dots of 10 mass% or more.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an ink composition containing highly reliable quantum dots, which can disperse the quantum dots at a high concentration without agglomerating.

(II) technical scheme

The present invention provides an ink composition comprising quantum dots, characterized in that the ink composition comprises a silsesquioxane polymer obtained by copolymerizing the quantum dots with silsesquioxane, or a silsesquioxane polymer obtained by copolymerizing the quantum dots with alkoxysilane.

According to this ink composition, it is possible to provide an ink composition containing highly reliable quantum dots by dispersing the quantum dots at a high concentration without agglomerating.

In this case, an ink composition is preferable in which the surface of the quantum dot is surface-modified with a silane coupling agent.

According to this ink composition, a silsesquioxane polymer obtained by copolymerizing the quantum dots and silsesquioxane or a silsesquioxane polymer obtained by copolymerizing the quantum dots and alkoxysilane can be easily formed, and an ink composition containing highly reliable quantum dots can be provided in which the quantum dots are dispersed at a high concentration without aggregation.

In this case, an ink composition is preferable in which the alkoxysilane is composed of 2 or more kinds of alkoxysilanes each having a different functional group.

According to this ink composition, the crosslinking degree of the silsesquioxane polymer can be controlled, the viscosity of the ink composition can be controlled, and an ink composition containing highly reliable quantum dots can be provided in which the quantum dots can be dispersed at a high concentration without aggregation. In addition, the viscosity can be adjusted according to the manufacturing process.

In this case, it is preferable that the ink composition comprises at least 2 or more kinds of alkoxysilane selected from the group consisting of trialkoxysilane, monoalkoxysilane and dialkoxysilane, and the viscosity of the ink composition is 1500mpa·s or less.

In this case, the ink composition is preferably one in which the silane coupling agent has 1 or more of an amino group, a thiol group, a carboxyl group, a phosphine oxide group, and an ammonium ion.

In this case, an ink composition is preferable in which the silsesquioxane has a functional group which is a reactive substituent of at least 1 kind selected from a vinyl group, an acrylic group, a methacryl group, a hydroxyl group, a phenolic hydroxyl group, an epoxy group, a glycidyl group, and a thiol group.

In this case, an ink composition having a functional group of the alkoxysilane, which is a reactive substituent of 1 or more kinds selected from vinyl, acryl, methacryl, hydroxyl, phenolic hydroxyl, epoxy, glycidyl, and thiol groups, is preferable.

According to this ink composition, a silsesquioxane polymer obtained by copolymerizing the quantum dots and silsesquioxane, or a silsesquioxane polymer obtained by copolymerizing the quantum dots and alkoxysilane can be easily formed. An ink composition containing highly reliable quantum dots can be provided in which the quantum dots can be dispersed at a high concentration without agglomerating.

The present invention also provides a method for producing a color filter, wherein the color filter is formed by discharging the ink composition described above onto a substrate by an inkjet method.

According to this method for producing a color filter, the ink composition containing highly reliable quantum dots can be easily and accurately formed by smoothly discharging the ink composition containing highly reliable quantum dots on a substrate by an inkjet method without agglomerating the quantum dots.

The present invention also provides a method for producing an ink composition, comprising a step of preparing quantum dots, a step of preparing an alkoxysilane, and a step of forming a copolymer of the quantum dots and the silsesquioxane by using the alkoxysilane as the silsesquioxane bonded to the surfaces of the quantum dots.

According to this method for producing an ink composition, an ink composition containing highly reliable quantum dots can be produced easily and reliably, which can disperse the quantum dots at a high concentration without agglomerating.

In this case, it is preferable that the process for preparing the quantum dot includes a process for forming a core and a process for forming a shell covering the core.

According to the method for producing the ink composition, quantum dots having a core-shell structure can be easily and surely produced, and an ink composition containing highly reliable quantum dots can be provided in which the quantum dots are dispersed at a high concentration without aggregation.

In this case, the method for producing the ink composition is preferably one in which the step of forming the copolymer includes a step of surface-modifying the surface of the quantum dot with a silane coupling agent, and a step of connecting the silsesquioxane to the surface of the quantum dot via the silane coupling agent.

In the method for producing an ink composition of this type, a silsesquioxane polymer obtained by copolymerizing the quantum dots with silsesquioxane or a silsesquioxane polymer obtained by copolymerizing the quantum dots with an alkoxysilane can be easily formed, and an ink composition containing highly reliable quantum dots can be provided in which the quantum dots can be dispersed at a high concentration without aggregation.

(III) beneficial effects

In order to achieve the above object, the present invention can produce an ink composition containing highly reliable quantum dots by copolymerizing quantum dots with silsesquioxane or copolymerizing quantum dots with alkoxysilane to produce a silsesquioxane polymer and curing the silsesquioxane polymer by a crosslinking reaction to disperse high-concentration quantum dots without aggregation.

According to the ink composition of the present invention, it is possible to produce an ink composition containing highly reliable quantum dots by dispersing the quantum dots at a high concentration without agglomerating.

According to the method for producing an ink composition of the present invention, an ink composition containing highly reliable quantum dots can be produced which enables the quantum dots to be dispersed at a high concentration without agglomerating.

According to the method for manufacturing a color filter of the present invention, the ink composition containing highly reliable quantum dots can be easily and accurately formed by smoothly discharging the ink composition containing highly reliable quantum dots by the inkjet method on the substrate without causing the quantum dots to be dispersed at a high concentration and to be aggregated.

Detailed Description

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

As described above, there is a problem in that an ink composition for inkjet, which can disperse quantum dots at a high concentration without agglomerating, contains highly reliable quantum dots, and can stably discharge the quantum dots, is obtained.

Accordingly, the inventors of the present application have conducted intensive studies to achieve such a technical problem. As a result, the present inventors have completed the present application by considering an ink composition containing a silsesquioxane polymer obtained by copolymerizing quantum dots and silsesquioxane or by copolymerizing quantum dots and alkoxysilane.

(Quantum dot)

In the present invention, the composition and the method of producing the quantum dot are not particularly limited, and the quantum dot can be selected according to the purpose.

(Composition of Quantum dots)

Examples of the composition of the quantum dot include a group II-IV semiconductor, a group III-V semiconductor, a group II-VI semiconductor, a group I-III-VI semiconductor, a group II-IV-V semiconductor, a group IV semiconductor, and a perovskite semiconductor.

(Structure of Quantum dot)

The quantum dot may have a core-only structure or a core-shell structure.

(Nuclear Material)

Specifically, as the core material, CdSe、CdS、CdTe、InP、InAs、InSb、AlP、AlAs、AlSb、ZnSe、ZnS、ZnTe、Zn₃P₂、GaP、GaAs、GaSb、CuInSe₂、CuInS₂、CuInTe₂、CuGaSe₂、CuGaS₂、CuGaTe₂、CuAlSe₂、CuAlS₂、CuAlTe₂、AgInSe₂、AgInS₂、AgInTe、AgGaSe₂、AgGaS₂、AgGaTe₂、PbSe、PbS、PbTe、Si、Ge、 graphene, csPbCl ₃、CsPbBr₃、CsPbI₃、CH₃NH₃PbCl₃, and mixed crystal or dopant added with these can be exemplified.

(Shell material)

As the shell material, ZnO、ZnS、ZnSe、ZnTe、CdS、CdSe、CdTe、AlN、AlP、AlAs、AlSb、GaN、GaP、GaAs、GaSb、InN、InP、InAs、AlSb、BeS、BeSe、BeTe、MgS、MgSe、MgTe、PbS、PbSe、PbTe、SnS、SnSe、SnTe、CuF、CuCl、CuBr、CuI、 and mixed crystals thereof can be exemplified.

(Shape of Quantum dot)

The quantum dots may be spherical, or may be cubic or rod-shaped. The shape of the quantum dot is not limited and can be freely selected.

(Average particle size of Quantum dots)

The particle size of the quantum dots may be appropriately selected according to the target wavelength range.

The average particle diameter of the quantum dots is preferably 20nm or less. If the average particle diameter is not less than the above value, the quantum size effect cannot be obtained, and the band gap due to the significant decrease in the light emission efficiency or the particle diameter cannot be controlled.

The particle diameter of the quantum dot can be calculated by measuring a particle image obtained by a transmission electron microscope (Transmission Electron Microscope: TEM) and calculating the particle diameter from an average value of the fixed maximum diameter of 20 or more particles, that is, the Feret (Feret) diameter. Of course, the method of measuring the average particle diameter is not limited to this, and other methods may be used for measurement.

(Ligand)

Ligands may be present on the surface of the quantum dots, and from the standpoint of dispersibility, the ligands preferably contain aliphatic hydrocarbons. Examples of such ligands include oleic acid, stearic acid, palmitic acid, myristic acid, lauric acid, capric acid, caprylic acid, oleylamine, stearylamine, dodecylamine, decylamine, octylamine, octadecylmercaptan, hexadecanemercaptan, tetradecanethiol, dodecylmercaptan, decylthiol, octylmercaptan, trioctylphosphine oxide, triphenylphosphine oxide, tributylphosphine oxide, and the like, and these ligands may be used singly or in combination of two or more.

(Silane coupling agent)

The surface of the quantum dot is preferably modified by a silane coupling agent.

As the silane coupling agent, a silane coupling agent having an amino group, a thiol group, a carboxyl group, a phosphine oxide group, and an ammonium ion is preferable.

As the silane coupling agent, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, aminophenyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl triethoxysilane, 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl (dimethoxy) methylsilane, triethoxysilylpropyl maleamic acid, [ (3-triethoxysilyl) propyl ] succinic anhydride, X-12-1135 (Shin-Etsu Chemical Co., manufactured by Ltd.) and diethyl phosphite ethyl triethoxysilane, 3-trihydroxypropyl methyl phosphate sodium salt, trimethyl [3- (trimethoxysilyl) propyl ] ammonium chloride can be exemplified.

The ink composition of the present invention comprises a silsesquioxane polymer obtained by copolymerizing quantum dots and silsesquioxane, or a silsesquioxane polymer obtained by copolymerizing quantum dots and alkoxysilane.

(Silsesquioxane Polymer obtained by copolymerizing Quantum dots with silsesquioxane)

In one embodiment of the present invention, quantum dots surface-modified with a silane coupling agent are copolymerized with silsesquioxane. The method of copolymerization is not particularly limited.

For example, the quantum dot and silsesquioxane subjected to surface modification can be copolymerized by mixing the quantum dot and silsesquioxane in a mixed solvent of toluene and ethanol, and adding a small amount of water and a catalyst to react.

The kind of the catalyst is not particularly limited, and an acid or a base may be used.

Examples of the catalyst include formic acid, hydrochloric acid, nitric acid, acetic acid, maleic acid, ammonia water, aqueous sodium hydroxide solution, and tetramethylammonium hydroxide.

The silsesquioxane may have a cage structure, a ladder structure, a random structure, or the like, and the structure thereof is not particularly limited and may be appropriately selected according to the purpose. Random structures are preferred from the viewpoints of dispersibility, uniformity, and the like of the quantum dots.

In addition, the functional group contained in the silsesquioxane is not limited, and may be appropriately substituted according to the purpose. From the viewpoint of curability, a substituent capable of undergoing a polymerization reaction or a crosslinking reaction is particularly preferable.

Examples of the functional group of the silsesquioxane include vinyl group, acryl group, methacryl group, hydroxyl group, phenolic hydroxyl group, epoxy group, glycidyl group, thiol group, and the like.

(Silsesquioxane Polymer obtained by copolymerizing Quantum dots and alkoxysilane)

In another embodiment of the present invention, the silsesquioxane polymer is produced by copolymerizing quantum dots surface-modified with a silane coupling agent with an alkoxysilane. The method of copolymerization is not particularly limited. As a method for synthesizing silsesquioxane, a method described in non-patent document 1 is known.

For example, the surface-modified quantum dot and the alkoxysilane are mixed in a mixed solvent of toluene and ethanol, and a small amount of water and a catalyst are added to react them, whereby the silsesquioxane polymer can be obtained.

The kind or amount of the catalyst to be added is not particularly limited, and an acid or a base can be used.

Examples of the catalyst include formic acid, hydrochloric acid, nitric acid, acetic acid, ammonia, and tetramethylammonium hydroxide.

The silane coupling agent is not particularly limited and may be appropriately selected according to the target resin characteristics. The silane coupling agent preferably has a vinyl group, an allyl group, a glycidyl group, a phenyl group, an acryl group, a methacryl group, and a thiol group in its functional group.

In addition, as the functional group, an alkoxysilane having 2 or more functional groups other than 1 may be used.

Examples of the silane coupling agent include trimethoxyvinylsilane, triethoxyvinylsilane, trimethoxy (4-vinylphenyl) silane, allyltriethoxysilane, allyltrimethoxysilane, triethoxy (3-glycidoxypropyl) silane, 3-glycidoxypropyl trimethoxysilane, [8- (glycidoxy) -n-octyl ] trimethoxysilane, KBM-573 (Shin-Etsu Chemical Co., ltd., (3-methacryloxypropyl) triethoxysilane, (3-methacryloxypropyl) trimethoxysilane, 3- (trimethoxysilyl) propyl acrylate, 3-mercaptopropyl triethoxysilane, and 3-mercaptopropyl trimethoxysilane.

In the case of such a silane coupling agent, the complexing property with quantum dots is high, and the affinity between silsesquioxane and quantum dots is also high, so that it is preferable.

In addition, the polarity of the quantum dot and the silsesquioxane polymer can be controlled, and good compatibility of the ink composition with any solvent can be obtained, so that it is also preferable.

In addition, the alkoxysilane may contain not only a trialkoxysilane but also a dialkoxysilane or a monoalkoxysilane. The trialkoxysilane may have the same functional group as the dialkoxysilane or the monoalkoxysilane, and may have different functional groups. By including the dialkoxysilane or monoalkoxysilane, the degree of crosslinking of the silsesquioxane obtained by copolymerization can be controlled, and the viscosity of the resin composition obtained can be controlled, and the viscosity can be adjusted according to the production process. For example, in the synthesis of silsesquioxane, a monoalkoxysilane having a long-chain alkyl group or a bulky substituent is mixed with a trialkoxysilane as a precursor, whereby a crosslinking reaction can be restricted and a reduction in viscosity can be performed.

Further, by mixing dialkoxysilane or monoalkoxysilane with trialkoxysilane, the degree of crosslinking can be reduced, and the viscosity can be reduced. The kind and ratio of these alkoxysilanes are not particularly limited, and may be appropriately selected according to the purpose.

The viscosity of the ink composition is preferably 1500 mPas or less, and particularly preferably 1000 mPas or less. The lower limit of the viscosity is not particularly limited, but is, for example, 1mpa·s or more. The viscosity of the ink composition can be measured, for example, by a rotary viscometer (DV-I manufactured by Brookfield Co.) at 25 ℃.

Examples of the functional group of the alkoxysilane include a reactive substituent of 1 or more of vinyl, acryl, methacryl, hydroxyl, phenolic hydroxyl, epoxy, glycidyl, and thiol groups.

The method for producing an ink composition of the present invention comprises a step 1 of preparing quantum dots, a step 2 of preparing an alkoxysilane, and a step 3 of forming a copolymer of the quantum dots and the silsesquioxane using the alkoxysilane as the silsesquioxane bonded to the surfaces of the quantum dots.

The process 1 for preparing the quantum dot preferably includes a process 1-1 for forming a core and a process 1-2 for forming a shell covering the core.

The copolymer forming step 3 preferably includes a step 3-1 of surface-modifying the surface of the quantum dot with a silane coupling agent, and a step 3-2 of connecting the silsesquioxane to the surface of the quantum dot via the silane coupling agent.

The ink composition of the present invention may contain a copolymer of the quantum dot and silsesquioxane subjected to surface treatment, a crosslinking agent, a polymerization initiator, a solvent, an antioxidant, a light scattering agent, and the like.

(Crosslinking agent)

As the crosslinking agent, a substance having 2 or more functional groups that react with polymerizable substituents contained in the copolymer of quantum dots and silsesquioxane is preferable. The amount of the crosslinking agent to be added is not particularly limited, and the combination of these functional groups is also not particularly limited, and may be appropriately selected according to the target curing characteristics.

Examples of the substituent capable of radical polymerization include vinyl, acryl, methacryl, and thiol groups, and can be suitably used.

Examples of the cationically polymerizable substituent include a hydroxyl group, a phenolic hydroxyl group, an epoxy group, a glycidyl group, an oxetanyl group, and an isocyanate group, and can be suitably used.

Examples of the crosslinking agent include dipentaerythritol hexaacrylate, octavinylsilsesquioxane, 2,4,6, 8-tetramethyl 2,4,6, 8-tetravinylcyclotetrasiloxane, 2,4, 6-trimethyl-2, 4, 6-trivinylcyclotrisiloxane, triallyl isocyanurate, trimethylolpropane triacrylate, and N, N' -methylenebis (acrylamide).

(Scatterer)

As the scattering body, inorganic particles, organic particles, or the like may be appropriately selected according to the purpose, and the particle diameter or the addition amount is desirably adjusted so that the light extraction efficiency is optimal according to the wavelength of the light source to be used or the structure of the emission wavelength and the wavelength conversion material.

Examples of the inorganic particles include silica, zirconia, alumina, barium titanate, and barium sulfate, and examples of the organic particles include PMMA, polystyrene, and polycarbonate.

(Polymerization initiator)

The ink composition of the present invention preferably contains a polymerization initiator.

The polymerization initiator may be a thermal or photopolymerization initiator, and may be suitably used according to the polymerization method.

Examples of the photo radical polymerization initiator include Irgacure290、Irgacure651、Irgacure754、Irgacure184、Irgacure2959、Irgacure907、Irgacure369、Irgacure379、Irgacure819、Irgacure1173, which is commercially available from BASF (registered trademark) in the Irgacure (Irgacure) series.

Further, among Darocure (registered trademark)) series, for example, TPO, darocure1173, and the like are exemplified.

In addition, a known thermal radical polymerization initiator or photo cation polymerization initiator may be contained without particular limitation.

The polymerization initiator content is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the polymer to be added.

(Solvent)

In order to improve the coatability, the ink composition of the present invention may contain a solvent. The solvent may be an organic solvent from the viewpoint of compatibility with the quantum dots, and examples thereof include ketones, alkylene glycol ethers, alcohols, and aromatic compounds.

Acetone, methyl ethyl ketone, cyclohexanone, and the like in the ketone group, methyl cellosolve (ethylene glycol monomethyl ether) in the alkylene glycol ether group, butyl cellosolve (ethylene glycol monobutyl ether), methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, ethylene glycol monopropyl ether, ethylene glycol monohexyl ether, ethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether, diethylene glycol methyl ether acetate, diethylene glycol ethyl ether, diethylene glycol propyl ether, diethylene glycol isopropyl ether, diethylene glycol butyl ether, diethylene glycol t-butyl ether acetate, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol propyl ether, triethylene glycol isopropyl ether, triethylene glycol butyl ether, triethylene glycol t-butyl ether, and the like in the alcohol group, methanol, ethanol, isopropanol, n-butanol, 3-methyl-3-methoxybutanol, and the like in the aromatic solvent group, and benzene, toluene, xylene can be utilized.

In the inkjet method, the solvent at the nozzle tip is volatilized, and solid components such as quantum dots are solidified to cause clogging of the nozzle tip, and there is a problem that stable discharge cannot be performed, and the solvent is preferably an organic solvent which is not easily volatilized, particularly preferably an organic solvent having a boiling point of 100 ℃. As such a solvent, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethylene glycol, propylene glycol, and the like can be suitably used.

(Content of Quantum dots)

The content of the quantum dots can be appropriately adjusted according to the target luminescence characteristics. The concentration of the quantum dots is preferably adjusted so that the absorption rate of the excitation light is 90% or more. The optimum concentration varies depending on the characteristics of the quantum dot, and is particularly preferably 10% by weight or more.

The method for producing a color filter of the present invention is a method for forming a color filter by discharging the ink composition of the present invention onto a substrate by an inkjet method.

(Inkjet device, system, substrate)

The ink composition containing quantum dots produced by the above method is applied to a substrate by an inkjet device, whereby a wavelength conversion material for color filter use can be obtained.

The ink jet system is not particularly limited, and a piezoelectric system, a bubble system, a valve system, or the like may be appropriately selected according to the ink characteristics.

The structure of the ink jet device is not particularly limited, and may be, for example, a single nozzle or a plurality of nozzles.

The substrate may be appropriately selected according to the purpose. For example, a silicon wafer, a glass substrate, a resin plate, a resin film, or the like can be exemplified. In addition, for the substrate, in order to improve the adhesiveness of the pattern, the surface treatment of the substrate may be performed with a silane coupling agent or the like.

(Curing of ink composition)

The ink composition of the present invention can be a mixture of a silsesquioxane polymer and a curable resin. At this time, the ink composition is discharged to the substrate, and then the resin layer is cured. In the case of a photocurable resin, the resin layer can be cured by irradiation with UV light, and in the case of a thermosetting resin, the resin layer can be cured by heating together with the substrate. The curing conditions are preferably adjusted according to the resin material or the pattern shape.

The thermosetting resin is preferably an acrylic resin having a (meth) acryloyl group in a side chain or a silicone resin containing an acid-crosslinkable group. The polymer may be a polymer derived from acrylic acid, methacrylic acid, acrylic acid ester, or methacrylic acid ester, or a copolymer obtained by combining a plurality of these, a polymer having glycidyl (meth) acrylate in the repeating unit, a polymer containing a siloxane skeleton, a urethane skeleton, a silylene skeleton, a norbornene skeleton, a fluorene skeleton, or an isocyanurate skeleton, or a polymer to be used may be appropriately selected depending on the application. Examples thereof include polyimide precursors such as acrylic resins, alkyd resins, melamine resins, epoxy resins, silicone resins, polyvinyl alcohols, polyvinylpyrrolidone, polyamides, polyamideimides, and polyimides, esterification products thereof, and reaction products of tetracarboxylic dianhydrides and diamines. Further, the polymer may be cured by incorporating a polymerizable substituent into the polymer and using the polymer in combination with a polymerization initiator. Examples of the substituent capable of radical polymerization include vinyl, acryl, methacryl, and thiol groups, and can be suitably used. Examples of the cationically polymerizable substituent include a hydroxyl group, a phenolic hydroxyl group, an epoxy group, a glycidyl group, an oxetanyl group, and an isocyanate group, and can be suitably used.

Examples

Hereinafter, examples and comparative examples of the present invention are shown, and the present invention is more specifically described, but is not limited thereto. In this example, as the quantum dot material, inP/ZnSe/ZnS core-shell quantum dots were used.

(Process 1 for preparing Quantum dots)

(Process for forming nuclei 1-1: process for synthesizing Quantum dot nuclei)

Into the flask were charged 0.23g (0.9 mmol) of palmitic acid, 0.088g (0.3 mmol) of indium acetate and 10mL of 1-octadecene, and the mixture was heated and stirred at 100℃under reduced pressure to dissolve the raw materials and deaerate for 1 hour.

Then, nitrogen was blown into the flask, and 0.75mL (0.15 mmol) of a solution obtained by mixing tris (trimethylsilyl) phosphine with trioctylphosphine and adjusting to 0.2M was added, and the temperature was raised to 300 ℃.

(Step 1-2 of forming core-covering Shell layer Synthesis step of Quantum dot Shell layer)

Next, 2.85g (4.5 mmol) of zinc stearate and 15mL of 1-octadecene were added to the other flask, and the mixture was heated and stirred at 100℃under reduced pressure, and the mixture was degassed for 1 hour while being dissolved, to prepare a 0.3M zinc octadecene stearate solution, and 3.0mL (0.9 mmol) was added to the reaction solution after nuclear synthesis and cooled to 200 ℃.

Next, 0.474g (6 mmol) of selenium and 4mL of trioctylphosphine were added to the other flask, heated to 150℃to dissolve the same, adjusted to a 1.5M solution of trioctylphosphine selenium, and the reaction solution after the nuclear synthesis step cooled to 200℃was heated to 320℃over 30 minutes, and a total of 0.6mL (0.9 mmol) of trioctylphosphine solution was added 0.1mL each time, kept at 320℃for 10 minutes, and cooled to room temperature.

0.44G (2.2 mmol) of zinc acetate was added thereto, and the mixture was heated and stirred at 100℃under reduced pressure to dissolve the zinc acetate. The flask was again purged with nitrogen and warmed to 230 ℃, 0.98mL (4 mmol) of 1-dodecanethiol was added and held for 1 hour.

The obtained solution was cooled to room temperature to prepare a solution containing core-shell quantum dots formed of InP/ZnSe/ZnS.

(Step 2 of preparing alkoxysilane)

6ML of (3-mercaptopropyl) triethoxysilane, 1mL of trimethoxy (3, 3-trifluoropropyl) silane, 3mL of phenyltrimethoxysilane and 6mL of (3-mercaptopropyl) triethoxysilane with 2mL of phenyltrimethoxysilane, 2mL of ethoxytrimethylsilane and 6mL of (3-methacryloxypropyl) trimethoxysilane with 2mL of phenyltrimethoxysilane, 2mL of ethoxytrimethylsilane and 7mL of 3-aminopropyl trimethoxysilane, 1mL of dodecyltrimethoxysilane with 2mL of ethoxytrimethylsilane and 10mL of (3-methacryloxypropyl) trimethoxysilane were prepared.

(Step 3) of forming a copolymer of quantum dots and silsesquioxane with alkoxysilane as silsesquioxane bonded to the surface of the quantum dots

(Process 3-1 for surface modification of surface of Quantum dot with silane coupling agent: surface treatment of Quantum dot)

After the completion of the reaction, the reaction mixture was cooled to room temperature, ethanol was added to precipitate a reaction solution, and the precipitate was centrifuged to remove the supernatant.

The same purification was again carried out to disperse it in toluene.

To the flask with nitrogen substitution was added a toluene solution of quantum dots.

To this was added 0.24mL (1.0 mmol) of (3-mercaptopropyl) triethoxysilane, and the mixture was stirred at room temperature for 24 hours.

(Step 3-2 (1) of connecting the silsesquioxane to the surface of the Quantum dots via the silane coupling agent: copolymerization of the Quantum dots and silsesquioxane 1)

To a nitrogen-substituted flask, 6mL of (3-mercaptopropyl) triethoxysilane, 1mL of trimethoxy (3, 3-trifluoropropyl) silane, 3mL of phenyltrimethoxysilane, and a surface-treated quantum dot solution were added so that the solid concentration was 20 parts by mass, and then 20mL of toluene and 10mL of methanol were mixed, followed by dropwise addition of 4.0mL of 1.0N hydrochloric acid while stirring at room temperature.

After the dropwise addition, the mixture was stirred at room temperature for 60 minutes, and then the solution was allowed to react at 60℃for 60 minutes while refluxing.

Then, vacuum was applied at 60℃for 180 minutes, and the solvent in the system was distilled off, whereby a copolymer (1) of quantum dots and silsesquioxane was obtained.

(Step 3-2 (2) of connecting silsesquioxane to the surface of Quantum dots via silane coupling agent: copolymerization of Quantum dots and silsesquioxane 2)

To the nitrogen-substituted flask, 6mL of (3-mercaptopropyl) triethoxysilane, 2mL of phenyltrimethoxysilane, 2mL of ethoxytrimethylsilane, and the surface-treated quantum dot solution were added so that the solid content concentration was 20 parts by mass, and then 20mL of toluene and 10mL of methanol were mixed.

While stirring at room temperature, 4.0mL of 1.0N hydrochloric acid was gradually added dropwise in small amounts.

Then, the solvent was distilled off while nitrogen was circulated in the system at 40 ℃, whereby a copolymer (2) of quantum dots and silsesquioxane was obtained.

(Step 3-2 (3) of attaching silsesquioxane to the surface of Quantum dots via silane coupling agent: copolymerization of Quantum dots and alkylsilane 3)

To the nitrogen-substituted flask, 6mL of (3-methacryloxypropyl) trimethoxysilane, 2mL of phenyltrimethoxysilane, 2mL of ethoxytrimethylsilane, and a surface-treated quantum dot solution were added so that the solid concentration was 20 parts by mass, and then 20mL of toluene and 10mL of methanol were mixed.

Then, the solvent was distilled off while nitrogen was circulated in the system at 40 ℃, whereby a copolymer (3) of quantum dots and silsesquioxane was obtained.

(Step 3-2 (4) of attaching silsesquioxane to the surface of Quantum dots via silane coupling agent: copolymerization of Quantum dots with alkylsilane 4)

To the nitrogen-substituted flask, 7mL of 3-aminopropyl trimethoxysilane, 1mL of dodecyl trimethoxysilane, 2mL of ethoxytrimethylsilane, and the surface-treated quantum dot solution were added so that the solid content concentration was 20 mass%, and then 20mL of toluene and 10mL of methanol were mixed.

Then, the solvent was distilled off while nitrogen was circulated in the system at 40 ℃, whereby a copolymer (4) of quantum dots and silsesquioxane was obtained.

(Step 3-2 (5) of attaching silsesquioxane to the surface of Quantum dots via silane coupling agent: copolymerization of Quantum dots with alkylsilane 5)

To the nitrogen-substituted flask, 10mL of (3-methacryloxypropyl) trimethoxysilane and the surface-treated quantum dot solution were added so that the solid concentration was 20 parts by mass, and then 20mL of toluene and 10mL of methanol were mixed.

Then, the solvent was distilled off while nitrogen was circulated in the system at 40 ℃, whereby a copolymer (5) of quantum dots and silsesquioxane was obtained.

(Synthesis of silsesquioxane Cross-linking agent)

To the nitrogen-substituted flask, 10mL of trimethoxyvinylsilane, 20mL of toluene, and 10mL of methanol were mixed, and 4.0mL of 1.0N hydrochloric acid was gradually added dropwise while stirring at room temperature.

Then, the inside of the system was evacuated at 60℃for 2 hours, and the solvent was distilled off.

In the flask, silsesquioxane having vinyl group (crosslinking agent (1)) was obtained.

To the nitrogen-substituted flask, 10mL of (3-methacryloxypropyl) trimethoxysilane, 20mL of toluene, and 10mL of methanol were mixed, and 4.0mL of 1.0N hydrochloric acid was added dropwise in small amounts while stirring at room temperature.

In the flask, silsesquioxane having a methacryloyl group (crosslinking agent (2)) was obtained.

To the nitrogen-substituted flask, 10mL of (3-glycidoxypropyl) trimethoxysilane, 20mL of toluene, and 10mL of methanol were mixed, and 4.0mL of 1.0N hydrochloric acid was gradually added dropwise while stirring at room temperature.

In the flask, silsesquioxane having a glycidyl group (crosslinking agent (3)) was obtained.

Example 1

The quantum dot silsesquioxane copolymer (1) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and octavinylsilsesquioxane was added as a crosslinking agent so that the molar ratio of mercapto groups in the copolymer to vinyl groups of the crosslinking agent was 1:1.

Then, 1 part by mass of Irgacure1173 was weighed out with respect to 100 parts by mass of the nonvolatile components of the mixture, and mixed.

Then, propylene glycol monomethyl ether acetate was added as a solvent so that the solid content concentration was 50%, to prepare an ink composition.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 1429 mPas (measured at 25 ℃).

Example 2

The quantum dot silsesquioxane copolymer (1) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and the crosslinking agent (1) was added as a crosslinking agent so that the ratio of mercapto groups in the copolymer to vinyl groups of the crosslinking agent was 1:1 in terms of molar ratio.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 1047 mPas (measured at 25 ℃).

Example 3

The quantum dot silsesquioxane copolymer (1) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and the crosslinking agent (2) was added as a crosslinking agent so that the ratio of mercapto groups in the copolymer to the methacryloyl groups of the crosslinking agent was 1:1 in terms of molar ratio.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 896 mPas (measured at 25 ℃).

Example 4

The quantum dot silsesquioxane copolymer (2) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and the crosslinking agent (1) was added as a crosslinking agent so that the molar ratio of mercapto groups in the copolymer to vinyl groups of the crosslinking agent was 1:1.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 788 mPas (measured at 25 ℃).

Example 5

The quantum dot silsesquioxane copolymer (2) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and the crosslinking agent (2) was added as a crosslinking agent so that the molar ratio of mercapto groups in the copolymer to vinyl groups of the crosslinking agent was 1:1.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 1024 mPas (measured at 25 ℃).

Example 6

The quantum dot silsesquioxane copolymer (3) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and the crosslinking agent (2) was added as a crosslinking agent so that the ratio of methacryloyl groups in the copolymer to methacryloyl groups of the crosslinking agent was 1:1 in terms of molar ratio.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 652 mPas (measured at 25 ℃).

Example 7

The quantum dot silsesquioxane copolymer (4) was weighed so as to contain 20wt% of quantum dots in terms of nonvolatile component ratio, and the crosslinking agent (3) was added as a crosslinking agent so that the molar ratio of amino groups in the copolymer to epoxy groups of the crosslinking agent was 1:1.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 795 mPas (measured at 25 ℃).

Comparative example 1

The quantum dot subjected to surface treatment alone was weighed so as to contain 20wt% of quantum dot in terms of nonvolatile component ratio, and the crosslinking agent (1) was added as a crosslinking agent so that the ratio of mercapto groups in the surface-treated QD solution to vinyl groups of the crosslinking agent was 1:1 in terms of molar ratio.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 1393 mPas (measured at 25 ℃).

Comparative example 2

The solvent of comparative example 1 was changed to toluene, and an ink composition was prepared.

The viscosity of the ink composition was measured by a rotary viscometer and found to be 1411 mPas (measured at 25 ℃).

The ink compositions obtained in examples 1 to 7 and comparative examples 1 to 2 were discharged onto a glass substrate at a pitch of 150. Mu.m, using an inkjet device (LaboJet-600 Bio manufactured by MICROJET Co.).

The discharged substrate was irradiated with light having a wavelength of 365nm and an output of 500mW/cm ² under an atmosphere to cure the substrate.

When the pattern remaining on the substrate was measured by a laser microscope (Olympus Corporation OLS-4100), it was confirmed that a dot pattern having an average thickness of 5 μm and a pattern size of 50 μm was formed.

(Spitting stability)

The case where the pattern was discharged at 10 lines 1 and 5 lines were continuously discharged, and the nozzle or the supply line was clogged or the ink was discharged poorly and the discharge was unstable during the continuous operation was evaluated as x.

(Evaluation of dispersibility)

The aggregates in the pattern were confirmed by electron microscopy.

Aggregates having a size of 1 μm or more were evaluated as x, and aggregates having no aggregate or a size of less than 1 μm were evaluated as o.

(Evaluation of Pattern properties)

The island-like pattern formed was observed, and the occurrence of defects such as irregularities in the size and shape of the pattern, defects in the pattern, and deviations in the pattern size were evaluated as x.

(Evaluation of luminescence characteristics of the formed Pattern)

The patterned samples prepared in the above examples and comparative examples were irradiated with laser light of 457nm (0.03 mW) using a LabRAM time Ev luti o n manufactured by HORIBA TECHNO SERVICE, co., ltd. To measure the island pattern region converted to light, and the light emission intensity, the light emission wavelength, and the half-peak width of the light converted to light were measured.

(Reliability evaluation)

The obtained pattern was subjected to a treatment at 85 ℃ and 85% rh (relative humidity) for 250 hours, and the fluorescence emission efficiency after the treatment was measured, and the initial reduction rate was confirmed to evaluate the reliability.

The evaluation results of examples and comparative examples are shown in tables 1 and 2.

TABLE 1

TABLE 2

From the results of tables 1 and 2, it was confirmed that the comparative example had nozzles clogged due to viscosity or aggregation, and the discharge of the ink composition was unstable, and the pattern defects were also generated.

On the other hand, the ejection of the examples was stable and no pattern defects were observed. Showing good patternability.

Further, when the reliability test results were compared, it was found that the stability of the examples was improved and the change with time was suppressed as compared with the comparative examples.

As described above, it was confirmed that by using the ink composition of the present invention, a wavelength conversion material having stable light emission characteristics and high reliability can be obtained.

The present specification includes the following schemes.

[1] An ink composition comprising quantum dots, characterized in that it comprises a silsesquioxane polymer obtained by copolymerizing the quantum dots with silsesquioxane, or a silsesquioxane polymer obtained by copolymerizing the quantum dots with alkoxysilane.

[2] The ink composition according to the above [1], wherein the surface of the quantum dot is surface-modified with a silane coupling agent.

[3] The ink composition according to the above [1] or [2], wherein the alkoxysilane is composed of 2 or more kinds of alkoxysilanes having different functional groups, respectively.

[4] The ink composition according to the above [1], the above [2] or the above [3], wherein the alkoxysilane is composed of at least 2 or more kinds of alkoxysilane selected from the group consisting of trialkoxysilane, monoalkoxysilane and dialkoxysilane, and the viscosity of the ink composition is 1500mPa and s or less.

[5] The ink composition according to the above [2], wherein the silane coupling agent has 1 or more of any of amino group, thiol group, carboxyl group, phosphine oxide group, and ammonium ion.

[6] The ink composition according to any one of [1] to [5], wherein the silsesquioxane has a functional group which is a reactive substituent of at least 1 of vinyl, acryl, methacryl, hydroxyl, phenolic hydroxyl, epoxy, glycidyl and thiol groups.

[7] The ink composition according to any one of the above [1] to [6], wherein the functional group of the alkoxysilane has at least one reactive substituent selected from the group consisting of a vinyl group, an acryl group, a methacryl group, a hydroxyl group, a phenolic hydroxyl group, an epoxy group, a glycidyl group and a thiol group.

[8] A method for producing a color filter, wherein the ink composition according to any one of [1] to [7] is discharged onto a substrate by an inkjet method to form a color filter.

[9] A method for producing an ink composition, characterized by comprising a step of preparing quantum dots, a step of preparing an alkoxysilane, and a step of forming a copolymer of the quantum dots and the silsesquioxane by using the alkoxysilane as the silsesquioxane bonded to the surfaces of the quantum dots.

[10] The method of producing an ink composition according to the above [9], characterized in that the step of preparing the quantum dot comprises a step of forming a core and a step of forming a shell covering the core.

[11] The method of producing an ink composition according to the above [9] or [10], wherein the step of forming the copolymer comprises a step of surface-modifying the surface of the quantum dot with a silane coupling agent, and a step of connecting the silsesquioxane to the surface of the quantum dot via the silane coupling agent.

In addition, the present invention is not limited to the above embodiments. The above embodiments are examples, and all embodiments having substantially the same constitution and exerting the same effects as the technical ideas described in the claims of the present invention are included in the scope of the present invention.

Claims

1. An ink composition comprising quantum dots, characterized by comprising a silsesquioxane polymer obtained by copolymerizing the quantum dots with silsesquioxane, or a silsesquioxane polymer obtained by copolymerizing the quantum dots with alkoxysilane.

2. The ink composition as defined in claim 1, wherein the surface of the quantum dot is surface-modified with a silane coupling agent.

3. The ink composition according to claim 1, wherein the alkoxysilane is composed of 2 or more alkoxysilanes having different functional groups.

4. The ink composition according to claim 1, wherein the alkoxysilane is composed of at least 2 or more kinds of alkoxysilanes selected from the group consisting of trialkoxysilane, monoalkoxysilane and dialkoxysilane, and the viscosity of the ink composition is 1500mpa·s or less.

5. The ink composition according to claim 2, wherein the silane coupling agent has 1 or more of any of an amino group, a thiol group, a carboxyl group, a phosphine oxide group, and an ammonium ion.

6. The ink composition according to claim 1, wherein the silsesquioxane has, as a functional group, a reactive substituent of 1 or more of vinyl, acryl, methacryl, hydroxyl, phenolic hydroxyl, epoxy, glycidyl, thiol groups.

7. The ink composition according to claim 1, wherein the functional group of the alkoxysilane has at least 1 reactive substituent selected from the group consisting of a vinyl group, an acryl group, a methacryl group, a hydroxyl group, a phenolic hydroxyl group, an epoxy group, a glycidyl group, and a thiol group.

8. A method for producing a color filter, comprising ejecting the ink composition according to any one of claims 1 to 7 onto a substrate by an inkjet method to form a color filter.

9. A method for producing an ink composition, comprising:

Preparing quantum dots;

process for preparing alkoxy silane

And a step of forming a copolymer of the quantum dot and the silsesquioxane by preparing the alkoxysilane into the silsesquioxane which is bonded to the surface of the quantum dot.

10. The method of producing an ink composition according to claim 9, wherein the step of preparing quantum dots comprises:

A step of forming a core

And forming a shell covering the core.

11. The method of producing an ink composition according to claim 9, wherein the step of forming the copolymer comprises:

a step of surface-modifying the surface of the quantum dot with a silane coupling agent, and

And a step of connecting the silsesquioxane to the surface of the quantum dots via the silane coupling agent.