Method for preparing recycled quantum dot ink composition, recycled quantum dot ink composition prepared thereby, and color filter and display device comprising same

Abstract

The present invention relates to a method for preparing a recycled quantum dot ink composition, a recycled quantum dot ink composition prepared by the preparation method, and a color filter and a display device which comprise a cured product of the recycled quantum dot ink composition, in which manufacturing costs incurred by applying expensive quantum dots can be reduced, the recycled quantum dot ink composition exhibits good viscosity and long-term storage stability, thus enabling effective application to inkjet processes, and a high-quality display device with further enhanced optical characteristics can be provided.

Description

Method for producing a regenerated quantum dot ink composition, a regenerated quantum dot ink composition produced thereby, a color filter and a display device comprising the same

[0001] The present invention relates to a method for producing a regenerated quantum dot ink composition, a regenerated quantum dot ink composition produced thereby, and a color filter and display device including the same.

[0002] Quantum dots (QDs) are semiconductor nanocrystals that can produce various colors by emitting light of different wavelengths depending on particle size without changing the type of material. They also have the advantage of higher color purity and light stability than existing light-emitting materials, and are attracting attention as a next-generation light-emitting element.

[0003] In particular, quantum dots, which have become a new trend in the display industry, can be applied to a variety of displays and electronic devices, in addition to TVs and LEDs. Quantum dots, represented by CdSe and InP, are rapidly advancing in terms of luminous efficiency (quantum yield), and synthesis methods with near-100% luminous efficiency are being introduced. Based on this, TVs using quantum dot sheets are currently being commercialized.

[0004] However, because these quantum dots are very expensive, methods that minimize material usage by only applying them to the desired areas are gaining attention. The most representative method is the inkjet process. Because inkjet processes only apply materials to the desired pixels, they prevent unnecessary material waste. This inkjet process utilizes a quantum dot ink composition that is solvent-free, has excellent quantum dot dispersibility, and possesses low viscosity.

[0005] In this regard, Korean Patent No. 10-1628065 discloses quantum dots and a quantum dot composition comprising the same, which exhibit excellent dispersibility and stability within a resin. However, these quantum dots suffer from insufficient long-term storage stability. Furthermore, even when using an inkjet process, there is a fundamental problem: material loss cannot be completely prevented.

[0006] Therefore, there is a need to develop a method for recovering and regenerating quantum dots from a quantum dot composition that is discarded due to reasons such as process loss and changes in physical properties resulting from long-term storage.

[0007] In order to solve the above-described problems, the present invention aims to provide a method for producing a regenerated quantum dot ink composition by recovering quantum dots from a waste quantum dot ink composition.

[0008] In addition, the present invention aims to provide a manufacturing method capable of further improving the viscosity and long-term storage stability of a regenerative quantum dot ink composition.

[0009] In addition, the present invention aims to provide a manufacturing method that makes it easy to consistently manage product quality by precisely controlling the content of quantum dots and scattering particles in a regenerative quantum dot ink composition.

[0010] In addition, the present invention aims to provide a color filter and a display device including a regenerative quantum dot ink composition manufactured by the above manufacturing method and a cured product thereof.

[0011] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0012] To achieve the above object, the present invention provides a method for producing a regenerated quantum dot ink composition, comprising: (a) removing scattering particles from a quantum dot ink composition; (b) recovering quantum dots from the quantum dot ink composition from which the scattering particles have been removed; (c) adding a ligand to the recovered quantum dots to re-substitute the ligand; and (d) dispersing the quantum dots from which the ligand has been re-substituted in a photopolymerizable monomer.

[0013] In the above manufacturing method, step (a) may include a step of selectively precipitating scattering particles by mixing a solvent into the quantum dot ink composition.

[0014] In the above manufacturing method, the solvent may be soluble in the quantum dots included in the quantum dot ink composition.

[0015] In the above manufacturing method, the solvent may have a polarity index of 2.4 to 7.2.

[0016] In the above manufacturing method, the solvent may be at least one selected from the group consisting of toluene, methyl t-butyl ether, xylene, benzene, diethyl ether, dichloromethane, dichloroethane, butyl acetate, isopropyl alcohol, butanol, tetrahydrofuran, propanol, acetonitrile, acetic acid, dimethylformamide, dimethyl sulfoxide, acetone, ethyl acetate, cyclohexyl acetate, chloroform, 2-butanone, dioxane, methanol, ethanol, and propylene glycol monomethyl ether acetate.

[0017] In the above manufacturing method, the content of scattering particles in the quantum dot ink composition from which the scattering particles have been removed may be 400 mg / L or less.

[0018] In the above manufacturing method, the step (b) may include a step of selectively precipitating quantum dots by mixing a nonsolvent into the quantum dot ink composition from which the scattering particles have been removed.

[0019] In the above manufacturing method, the non-solvent may have a polarity index of 1 or less.

[0020] In the above manufacturing method, the ligand may include a ligand having 3 to 40 carbon atoms and including a carboxyl group.

[0021] In the above manufacturing method, the ligand having 3 to 40 carbon atoms and including a carboxyl group may be a compound represented by chemical formula 2.

[0022] [Chemical Formula 2]

[0023]

[0024] (In the above chemical formula 2, L is a single bond or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkylene group and a substituted or unsubstituted C1 to C20 alkenylene, A is a single bond or is a C1 to C20 alkylene group or alkenylene group including at least one functional group selected from the group consisting of ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), sulfonyl (-SO2-), sulfide (-S-), and sulfoxide (-SO-), and R is hydrogen or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkyl group and a substituted or unsubstituted C1 to C20 alkenyl group.)

[0025] In the above manufacturing method, the compound represented by the above chemical formula 2 may be at least one selected from the group consisting of 2-carboxyethyl acrylate, mono-2-(acryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl maleate, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and 2-(2-methoxyethoxy)acetic acid.

[0026] In the above manufacturing method, the photopolymerizable monomer may include a (meth)acrylate monomer.

[0027] In the above manufacturing method, the quantum dot ink composition of step (a) may be a waste quantum dot ink composition.

[0028] In addition, the present invention provides a regenerative quantum dot ink composition manufactured by the above manufacturing method.

[0029] In the above composition, the regenerative quantum dot ink composition may have a viscosity change of +1.6 cps or less compared to the initial viscosity when stored at 50°C for 4 weeks.

[0030] In the above composition, the regenerative quantum dot ink composition may be for inkjet printing.

[0031] In addition, the present invention provides a color filter including a cured product of the above-described regenerative quantum dot ink composition.

[0032] In addition, the present invention provides a display device including the color filter.

[0033] The method for manufacturing a regenerated quantum dot ink composition according to the present invention provides the effect of reducing the manufacturing cost of a product to which expensive quantum dots are applied by recovering quantum dots from a waste quantum dot ink composition to manufacture a regenerated quantum dot ink composition and using the same in the manufacture of color filters and the like.

[0034] In addition, the present invention provides an effect of further improving the viscosity and long-term storage stability of the regenerated quantum dot ink composition by including a step of re-substituting the ligand of the quantum dot recovered from the waste quantum dot ink composition.

[0035] In addition, the present invention selectively removes scattering particles included in a waste quantum dot ink composition and then recovers quantum dots, thereby enabling precise control of the content of quantum dots and scattering particles in a regenerated quantum dot ink composition, thereby providing an effect that makes it easy to consistently manage the quality of a product to which quantum dots are applied.

[0036] In addition, the regenerated quantum dot ink composition manufactured by the method for manufacturing the regenerated quantum dot ink composition of the present invention has excellent viscosity and long-term storage stability, and thus can be effectively applied to an inkjet process, thereby providing a high-quality display device.

[0037] Figure 1 is a process diagram schematically showing a method for manufacturing a regenerative quantum dot ink composition according to the present invention.

[0038] Figure 2 is a diagram showing the results of evaluating the scattering particle settling properties of four solvents (acetone, ethyl acetate (EA), cyclohexyl acetate (CHA), and isopropyl alcohol (IPA)) for (a) a green quantum dot ink composition and (b) a red quantum dot ink composition.

[0039] The present invention relates to a method for producing a regenerated quantum dot ink composition by recovering quantum dots from a waste quantum dot ink composition and then re-substituting a ligand, a regenerated quantum dot ink composition produced by the method, and a color filter and display device including a cured product of the regenerated quantum dot ink composition.

[0040] More specifically, the present invention relates to a method for producing a regenerated quantum dot ink composition, comprising: (a) removing scattering particles from a quantum dot ink composition; (b) recovering quantum dots from the quantum dot ink composition from which the scattering particles have been removed; (c) adding a ligand to the recovered quantum dots to re-substitute the ligand; and (d) dispersing the quantum dots from which the ligand has been re-substituted in a photopolymerizable monomer.

[0041] In addition, the present invention relates to a regenerative quantum dot ink composition manufactured by the above manufacturing method.

[0042] In addition, the present invention relates to a color filter including a cured product of the above-described regenerative quantum dot ink composition and a display device including the same.

[0043]

[0044] All terms (including technical and scientific terms) used in this specification, unless otherwise defined, may be used in their common sense by those of ordinary skill in the art to which the present invention pertains. Furthermore, terms defined in commonly used dictionaries are not to be interpreted ideally or excessively unless explicitly and specifically defined otherwise.

[0045] Additionally, as used herein, the terms “comprises” and / or “comprising” are used to mean that they do not exclude the presence or addition of one or more other components and / or steps other than the mentioned components and / or steps.

[0046] Additionally, as used herein, “(meth)acrylate” means acrylate and methacrylate, “(meth)acrylic” means acrylic and methacrylic, and “(meth)acryloyl” means acryloyl and methacryloyl.

[0047] In addition, as used herein, "monomer" and "monomer" have the same meaning. In the present invention, the monomer is distinguished from oligomers and polymers, and refers to a compound having a weight average molecular weight of 1,000 or less. As used herein, the "photopolymerizable monomer" refers to a monomer containing a group involved in a photopolymerization reaction, such as a (meth)acrylate group.

[0048] As used herein, "substitution" means that a hydrogen atom in a compound or functional group is substituted with a C1 to C30 alkyl group, a C2 to C30 alkenyl group, a C2 to C30 alkynyl group, a C1 to C30 alkoxy group, a C1 to C30 heteroalkyl group, a C3 to C30 heteroalkylaryl group, a C3 to C30 cycloalkyl group, a C3 to C15 cycloalkenyl group, a C6 to C30 cycloalkynyl group, a C2 to C30 heterocycloalkyl group, a halogen (-F, -Cl, -Br or -I), a hydroxyl group (-OH), a nitro group (-NO2), a cyano group (-CN), an ester group (-C(=O)-OR, where R is a C1 to C10 alkyl group or an alkenyl group), an ether group (-OR, where R is a C1 to C10 alkyl group or an alkenyl group). It means substituted with a substituent selected from an alkenyl group), a carbonyl group (-C(=O)-R, where R is a C1 to C10 alkyl group or an alkenyl group), a carboxyl group (-COOH), and a combination thereof.

[0049] As used herein, the term "organic group" means a straight or branched chain alkyl group having a carbon atom of 1 to 30 carbon atoms, a straight or branched chain alkenyl group having a carbon atom of 2 to 30 carbon atoms, or a straight or branched chain alkynyl group having a carbon atom of 2 to 30 carbon atoms. In addition, the alkyl group, alkenyl group, and alkynyl group may each be substituted or unsubstituted.

[0050] As used herein, "alkyl" refers to a monovalent substituent derived from a straight or branched chain saturated hydrocarbon having 1 to 40 carbon atoms. Examples of the "alkyl" include, but are not limited to, methyl, ethyl, propyl, isobutyl, sec-butyl, pentyl, iso-amyl, hexyl, and the like.

[0051] As used herein, "alkenyl" refers to a monovalent substituent derived from a straight or branched chain unsaturated hydrocarbon having 2 to 40 carbon atoms and at least one carbon-carbon double bond. Examples of the "alkenyl" include, but are not limited to, vinyl, allyl, isopropenyl, and 2-butenyl.

[0052] As used herein, "alkynyl" refers to a monovalent substituent derived from a straight or branched chain unsaturated hydrocarbon having 2 to 40 carbon atoms and at least one carbon-carbon triple bond. Examples of the "alkynyl" include, but are not limited to, ethynyl and propynyl.

[0053]

[0054] The method for producing a regenerated quantum dot ink composition of the present invention is characterized by recovering quantum dots from the quantum dot ink composition and using them in the production of the regenerated quantum dot ink composition. Prior to describing the manufacturing method according to the present invention, the quantum dot ink composition that is the target of quantum dot recovery and each component included therein will be described.

[0055]

[0056] <Quantum Dot Ink Composition>

[0057] A quantum dot ink composition for use in an inkjet process comprises quantum dots and a photopolymerizable monomer. Furthermore, the quantum dot ink composition may further comprise, as necessary, one or more additives selected from the group consisting of a photoinitiator, scattering particles, polymerization inhibitors, stabilizers, and other additives. Furthermore, the quantum dot ink composition may be a solvent-free quantum dot ink composition that does not contain a solvent.

[0058]

[0059] quantum dots

[0060] Quantum dots (QDs) are nano-sized semiconductor materials that can have different energy band gaps depending on their size and composition, and thus can emit light of various emission wavelengths.

[0061] These quantum dots may have a homogeneous single-layer structure; a multi-layer structure such as a core-shell configuration, a gradient structure, or a mixture thereof. When the shell is multi-layered, each layer may contain different components, such as (quasi)metal oxides.

[0062] Quantum dots (QDs) can be freely selected from group II-VI compounds, group III-V compounds, group IV-VI compounds, group IV elements, group IV compounds, and combinations thereof. When the quantum dots are in a core-shell form, the core and shell can each be freely composed of the components exemplified below.

[0063] For example, the Group II-VI compound is a binary compound selected from the group consisting of CdO, CdS, CdSe, CdTe, ZnO, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, MgSe, MgS and mixtures thereof; a ternary compound selected from the group consisting of CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS and mixtures thereof; and may be selected from the group consisting of four-element compounds selected from the group consisting of CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe and mixtures thereof.

[0064] In another example, the III-V group compound may be selected from the group consisting of binary compounds selected from the group consisting of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, and mixtures thereof; ternary compounds selected from the group consisting of GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, and mixtures thereof; and quaternary compounds selected from the group consisting of GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb, and mixtures thereof.

[0065] In another example, the group IV-VI compound may be selected from the group consisting of binary compounds selected from the group consisting of SnS, SnSe, SnTe, PbS, PbSe, PbTe, and mixtures thereof; ternary compounds selected from the group consisting of SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, and mixtures thereof; and quaternary compounds selected from the group consisting of SnPbSSe, SnPbSeTe, SnPbSTe, and mixtures thereof.

[0066] As another example, the group IV element may be selected from the group consisting of Si, Ge, and mixtures thereof. The group IV compound may be a binary compound selected from the group consisting of SiC, SiGe, and mixtures thereof.

[0067] The aforementioned binary, ternary, or quaternary compounds may exist within the particle at a uniform concentration, or may exist within the same particle with partially different concentration distributions. Furthermore, one quantum dot may have a core / shell structure, surrounding another quantum dot. The interface between the core and shell may have a concentration gradient, with the concentration of the element within the shell decreasing toward the center.

[0068] The shape of the quantum dot is not particularly limited as long as it is a shape commonly used in the field. For example, nanoparticles, nanotubes, nanowires, nanofibers, nanoplatelets, etc. in the shape of spherical, rod-shaped, pyramidal, disc-shaped, multi-armed, or cubic particles can be used.

[0069] In addition, the size of the quantum dots is not particularly limited and can be appropriately controlled within a typical range known in the art. For example, the average particle diameter (D50) of the quantum dots can be about 2 to 10 nm. When the particle diameter of the quantum dots is controlled in this way to be approximately in the range of about 2 to 10 nm, light of a desired color can be emitted. For example, when the particle diameter of the quantum dot core / shell containing InP is about 5 to 6 nm, light with a wavelength of about 520 to 550 nm can be emitted. On the other hand, when the particle diameter of the quantum dot core / shell containing InP is about 7 to 8 nm, light with a wavelength of about 620 to 640 nm can be emitted. For example, non-cadmium (Cd) group III-V QDs (e.g., InP, InGaP, InZnP, GaN, GaAs, GaP) can be used as blue-emitting QDs (quantum dots).

[0070] In addition, the quantum dots may have a full width of half maximum (FWHM) of an emission wavelength spectrum of about 40 nm or less, and color purity and color reproducibility may be improved within this range. In addition, since light emitted by these quantum dots is emitted in all directions, a wide viewing angle may be improved.

[0071] The content of the quantum dots may be 1 to 60 wt%, preferably 20 to 50 wt%, based on the total weight of the quantum dot ink composition.

[0072]

[0073] ligand

[0074] The quantum dot has a ligand layer on its surface, and the ligand contained in the ligand layer serves to modify the surface of the quantum dot. Due to the hydrophobic surface characteristics of the quantum dot, there is a barrier to dispersion of the photopolymerizable monomer. However, by modifying the surface of the quantum dot with an appropriate ligand, the miscibility of the quantum dot with the photopolymerizable monomer can be improved.

[0075] The above ligand is not particularly limited as long as it can improve the compatibility of the quantum dot with the photopolymerizable monomer, but may include, for example, a first ligand represented by the following chemical formula 1 and a second ligand having 3 to 40 carbon atoms and including a carboxyl group.

[0076] [Chemical Formula 1]

[0077]

[0078] In the above chemical formula 1,

[0079] M is a metal of 2 to 4 valence,

[0080] X is an organic group having 3 to 20 carbon atoms,

[0081] n is an integer from 2 to 4.

[0082]

[0083] The above first ligand may be a metal-thiol compound formed by reacting a metal salt and a thiol compound.

[0084] In the above chemical formula 1, M is a metal having a valence of 2 to 4. For example, M is a metal of group 2 to 14, and may be Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, or Sn.

[0085] In the above chemical formula 1, n is determined according to the valence of M and is an integer from 2 to 4.

[0086] In addition, in the above chemical formula 1, X may be an organic group having 3 to 20 carbon atoms. For example, the above X may be an ester (-C(=O)O-), an ether (-O-), a carbonyl (-C(=O)-), a carboxyl group (-C(=O)-OH), a sulfonyl group (-SO2-), a sulfide (-S-), a sulfoxide (-SO-), an alkoxy group (C n H 2n+1It may be an alkylene group or alkenylene group having 3 to 20 carbon atoms and including at least one functional group selected from the group consisting of an ester (-C(=O)O-) and a hydroxyl group (-OH). Specifically, X may be an organic group having 4 to 15 carbon atoms and including an ester (-C(=O)O-) functional group.

[0087] The compound represented by the above chemical formula 1 may include, but is not limited to, Zn-(3-methoxybutyl 3-mercaptopropionate)2, Zn-(3-methoxybutyl thioglycolate)2, Zn-(2-ethylhexyl thioglycolate)2, Zn-(butyl mercaptopropionate)2, Zn-(isopropyl mercaptopropionate)2, and Zn-(PEG-Thiol)2, for example.

[0088]

[0089] The second ligand may have 3 to 40 carbon atoms and may include a carboxyl group. In addition, the second ligand may not include a thiol group.

[0090] The above second ligand may be a compound represented by the following chemical formula 2.

[0091] [Chemical Formula 2]

[0092]

[0093] In the above chemical formula 2,

[0094] L is a single bond or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkylene group and a substituted or unsubstituted C1 to C20 alkenylene.

[0095] A is a single bond or a C1 to C20 alkylene group or alkenylene group containing at least one functional group selected from the group consisting of ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), sulfonyl (-SO2-), sulfide (-S-), and sulfoxide (-SO-).

[0096] R is hydrogen, or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkyl group and a substituted or unsubstituted C1 to C20 alkenyl group.

[0097] Preferably, in the above chemical formula 2, A may include an ester (-COO-), an ether (-O-), or a combination thereof. In addition, A may be a C2 to C15 alkylene group or alkenylene group, preferably a C2 to C10 alkylene group or alkenylene group.

[0098] Examples of the compound represented by the above chemical formula 2 include, but are not limited to, 2-carboxyethyl acrylate, mono-2-(acryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl maleate, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and 2-(2-methoxyethoxy)acetic acid.

[0099] The molar ratio of the first ligand and the second ligand may be 1:0.1 to 20, preferably 1:0.2 to 10, but is not limited thereto.

[0100] Additionally, the mixing weight ratio of the quantum dot and the ligand may be 1:0.05 to 1, preferably 1:0.1 to 0.5. Here, the ligand means the sum of the first ligand and the second ligand.

[0101]

[0102] photopolymerizable monomer

[0103] Photopolymerizable monomers control the overall crosslinking density of the polymer matrix, i.e., the formulation in which quantum dots (QDs) are dispersed, thereby shaping the matrix's structure and overall physical properties. They can also improve flexibility and adhesion to other materials.

[0104] The above photopolymerizable monomer may include a (meth)acrylate monomer. Any monomer commonly used in the art may be used without any particular limitation.

[0105] The above (meth)acrylate monomer may include at least one of a (meth)acrylic group, a vinyl group, and an allyl group. Specifically, 1,6-hexanediol diacrylate, 1,6-cyclohexanediol diacrylate, 2,2-dimethyl-1,3-propanediol diacylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate, isobonyl acrylate, isobonyl methacrylate, tetrahydrofuryl Tetrahydrofuryl acrylate, acryloyl morpholine, 2-phenoxyethyl acrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol mono(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate,Examples include dipentaerythritol hexaacrylate and dipentaerythritol hexamethacrylate. These can be used alone or in combination of two or more.

[0106] The content of the photopolymerizable monomer may be 35 to 80 wt%, preferably 45 to 70 wt%, based on the total weight of the quantum dot ink composition.

[0107]

[0108] photoinitiator

[0109] A photoinitiator is a component that initiates photopolymerization by being excited by a light source such as ultraviolet (UV) rays. Any photopolymerization photoinitiator commonly used in the art can be used without limitation. For example, acetophenone compounds, benzophenone compounds, thioxanthone compounds, benzoin compounds, triazine compounds, oxime compounds, etc. can be used.

[0110] Non-limiting examples of usable photoinitiators include Ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate, Irgacure 184, Irgacure 369, Irgacure 651, Irgacure 819, Irgacure 907, TPO-L, Benzionalkylether, Benzophenone, Benzyl dimethyl katal, Hydroxycyclohexyl phenyl acetone, Chloroacetophenone, 1,1-Dichloro acetophenone, Diethoxy acetophenone, Hydroxy Acetophenone, There are 2-Chloro thioxanthone, 2-ETAQ (2-EthylAnthraquinone), 1-Hydroxy-cyclohexyl-phenyl-ketone, 2-Hydroxy-2-methyl-1-phenyl-1-propanone, 2-Hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methylbenzoylformate, etc. These can be used alone or in combination of two or more.

[0111] The content of the photoinitiator can be appropriately adjusted within a range known in the art. For example, it can be 0.01 to 10 wt%, and preferably 0.1 to 5 wt%, based on the total weight of the quantum dot ink composition.

[0112]

[0113] scattering particles

[0114] Scattering particles can increase the amount of light emitted from a quantum dot by reflecting light that has not yet been absorbed by the quantum dot and allowing the reflected light to be absorbed by the quantum dot, or can increase the overall light conversion efficiency by reflecting light emitted from the quantum dot and increasing the optical path.

[0115] The scattering particles may be any particles known in the art without limitation. For example, the scattering particles may include barium sulfate (BaSO4), calcium carbonate (CaCO3), titanium dioxide (TiO2), zirconia (ZrO2), or a combination thereof, and the average particle diameter (D50) may be, but is not limited to, 150 nm to 250 nm.

[0116] The content of the above scattering particles can be appropriately adjusted within a range known in the art. For example, it can be 0.01 to 10 wt%, and preferably 0.1 to 5 wt%, based on the total weight of the quantum dot ink composition.

[0117]

[0118] polymerization inhibitor

[0119] A polymerization inhibitor is a substance that forms a radical or compound with low reactivity that cannot cause a polymerization reaction by reacting with a radical, and can be added to control the speed of the photopolymerization reaction.

[0120] The polymerization inhibitor described above may be any material known in the art without limitation. For example, polymerization inhibitors may include quinone compounds, phenol or aniline compounds, and aromatic nitro or nitroso compounds. These may be used alone or in combination of two or more.

[0121] Specifically, examples of the quinone compounds include hydroquinone (HQ), methylhydroquinone (THQ), hydroquinone monomethyl ether (MEHQ), and hydroquinone monoethyl ether (EEHQ), 1,4-benzoquinone (BQ), 2,5-diphenylbenzoquinone (DPBQ), methyl-1,4-benzoquinone (MBQ), and phenyl-1,4-benzoquinone (PBQ).

[0122] Examples of the above phenol or aniline compounds include 2,6-di-tert-butyl-4-methylphenol (BHT), 2,6-diphenyl-4-octadecyloxyphenol, and catechol.

[0123] Examples of the above aromatic nitro or nitroso compounds include phenothiazine, bis(α-methylbenzyl)phenothiazine, 3,7-dioctylphenothiazine, bis(α,α-dimethylbenzyl)phenothiazine; dimethyldithiocarbamic acid, diethyldithiocarbamic acid, dipropyldithiocarbamic acid, dibutyldithiocarbamic acid, and diphenyldithiocarbamic acid.

[0124] The content of the above polymerization inhibitor can be appropriately adjusted within a range known in the art. For example, it can be 0.01 to 2 wt%, and preferably 0.05 to 1 wt%, based on the total weight of the quantum dot ink composition.

[0125]

[0126] stabilizator

[0127] Stabilizers can be added to improve the stability and dispersibility of quantum dots. Stabilizers can stabilize quantum dots by substituting them onto the shell surface of the quantum dot, thereby improving the dispersion stability of the quantum dot in the solvent.

[0128] Any stabilizer capable of enhancing the stability and dispersibility of quantum dots in the art may be used without limitation. For example, a thiol-based stabilizer may be used. The thiol-based stabilizer can enhance the dispersibility of quantum dots in a photopolymerizable monomer. Furthermore, the thiol group of the thiol-based stabilizer can react with the acrylic group of the photopolymerizable monomer to form a covalent bond, thereby enhancing the heat resistance of the quantum dot composition.

[0129] The above thiol stabilizer may have 7 or more carbon atoms and, depending on its structure, may have 2 to 10, for example, 2 to 6, thiol groups (-SH) at the terminal, but is not particularly limited thereto. Non-limiting examples of usable thiol stabilizers include pentaerythritol tetrakis(3-mercaptopropionate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(mercaptoacetate), trimethylolpropane tris(2-mercaptoacetate), glycol di-3-mercaptopropionate, or mixtures thereof.

[0130]

[0131] Other additives

[0132] In addition to the aforementioned components, the quantum dot ink composition may, as needed, utilize additives known in the art without limitation. The content of the additives may be appropriately adjusted within a range known in the art.

[0133] Examples of usable additives include silane compounds, siloxane compounds, antioxidants, polymerization inhibitors, lubricants, surface conditioners, surfactants, adhesion promoters, anti-foaming agents, slip agents, solvents, wetting agents, light stabilizers, stain inhibitors, softeners, thickeners, polymers, etc. These may be used alone or in combination of two or more.

[0134] Silane compounds provide adhesive properties to the matrix, and siloxane compounds provide wetting properties. Any known silane and siloxane compounds can be used without limitation.

[0135] Antioxidants suppress discoloration due to heat or light irradiation and discoloration due to various oxidizing gases such as ozone, active oxygen, NOx, and SOx (X is an integer). In the present invention, by adding an antioxidant, it is possible to prevent discoloration of the matrix or reduce film thickness reduction due to decomposition. Examples of usable antioxidants include hydrazides, hindered amine antioxidants, nitrogen-containing heterocyclic mercapto compounds, thioether antioxidants, hindered phenol antioxidants, ascorbic acid, zinc sulfate, thiocyanates, thiourea derivatives, sugars, nitrites, sulfites, thiosulfates, hydroxylamine derivatives, and the like.

[0136] A leveling agent may be included to increase the adhesive strength within the composition by leveling it so that the quantum dot composition can be coated evenly and smoothly when coated. The leveling agent may include an acrylic agent, a silicone agent, or the like, either singly or in combination of two or more. For example, a polyether-modified polydimethylsiloxane may be included, and a (meth)acryloyl group may be added to the polyether chain.

[0137] A surfactant may be included to ensure mixing and uniform application of the quantum dot composition. Conventional cationic, anionic, zwitterionic, and nonionic surfactants known in the art may be used as the surfactant. For example, at least one of a fluorinated surfactant, a silicone-based surfactant, and a fluorinated / silicon-based surfactant may be used.

[0138] Light stabilizers act as UV absorbers and enhance the weatherability of the matrix. Softeners mitigate cracking within the dried polymer matrix, thereby improving impact and flexural resistance by mitigating cracking within the cured matrix.

[0139]

[0140] <Method for producing a regenerative quantum dot ink composition>

[0141] The present invention provides a method for producing a regenerated quantum dot ink composition, comprising: (a) removing scattering particles from a quantum dot ink composition; (b) recovering quantum dots from the quantum dot ink composition from which the scattering particles have been removed; (c) adding a ligand to the recovered quantum dots to re-substitute the ligand; and (d) dispersing the quantum dots from which the ligand has been re-substituted in a photopolymerizable monomer.

[0142] In the method for manufacturing a regenerative quantum dot ink composition of the present invention, the contents of the above-described <quantum dot ink composition> can be equally applied to matters regarding the quantum dot ink composition that is the target of quantum dot recovery and each component included therein.

[0143]

[0144] Figure 1 is a schematic diagram illustrating a method for manufacturing a regenerative quantum dot ink composition according to the present invention. Hereinafter, the manufacturing method of the present invention will be described in detail for each step with reference to Figure 1.

[0145]

[0146] (a) a step of removing scattering particles from a quantum dot ink composition;

[0147] In the present invention, the quantum dot ink composition of step (a) may be a waste quantum dot ink composition. The waste quantum dot ink composition is not particularly limited as long as it is a discarded quantum dot ink composition, and may refer to, for example, a quantum dot ink composition discarded due to loss occurring during an inkjet process, and a quantum dot ink composition that was not actually used in an inkjet process but was discarded because its physical properties, such as viscosity and dispersibility, changed due to long-term storage, etc., making it no longer usable in an inkjet process.

[0148] Typically, quantum dot ink compositions contain scattering particles along with quantum dots, so it is necessary to first remove the scattering particles from the quantum dot ink composition before recovering the quantum dots. If the scattering particles are not removed at all or not sufficiently from the quantum dot ink composition when recovering the quantum dots, a certain amount of scattering particles may be mixed in the recovered quantum dots. It is difficult to accurately determine the content of scattering particles mixed in the recovered quantum dots. Therefore, when manufacturing a regenerated quantum dot ink composition using the recovered quantum dots, it is impossible to precisely control the content of quantum dots and scattering particles, which may cause problems in maintaining consistent quality.

[0149] In one embodiment of the present invention, step (a) of the present invention may include a step of selectively precipitating scattering particles by mixing a solvent into the quantum dot ink composition. In this case, the solvent may be a solvent that is insoluble in the scattering particles included in the quantum dot ink composition and soluble in the quantum dots.

[0150] The solvent is not particularly limited as long as it can selectively precipitate scattering particles, but preferably, a solvent having a polarity index of 2.4 to 7.2 can be used, and more preferably, a solvent having a polarity index of 4.1 to 5.2 can be used, and accordingly, there is an advantage in that the efficiency of selectively precipitating only scattering particles from the quantum dot ink composition can be increased. The solvent having a polarity index of 2.4 to 7.2 may include, but is not limited to, at least one selected from the group consisting of toluene, methyl t-butyl ether, xylene, benzene, diethyl ether, dichloromethane, dichloroethane, butyl acetate, isopropyl alcohol, butanol, tetrahydrofuran, propanol, acetonitrile, acetic acid, dimethylformamide, dimethyl sulfoxide, acetone, ethyl acetate, cyclohexyl acetate, chloroform, 2-butanone, dioxane, methanol, ethanol, and propylene glycol monomethyl ether acetate. Among these, it may be preferable to include at least one selected from the group consisting of acetone, ethyl acetate, cyclohexyl acetate, chloroform, 2-butanone, dioxane, methanol, ethanol, and propylene glycol monomethyl ether acetate, each having a polarity index of 4.1 to 5.2.

[0151] Meanwhile, if a solvent having a polarity index of less than 2.4 or greater than 7.2 is used as the solvent, quantum dots may be precipitated together with scattering particles from the quantum dot ink composition, and thus the solvent may not be suitable as a solvent for selectively removing only scattering particles from the quantum dot ink composition.

[0152] The above solvent can be mixed in an amount of 1 to 4 times the total weight of the quantum dot ink composition, preferably 1.5 to 3 times the total weight.

[0153] The above-deposited scattering particles can be removed through centrifugation, thereby obtaining a quantum dot ink composition from which scattering particles have been removed (hereinafter also referred to as a quantum dot dispersion from which scattering particles have been removed).

[0154] The centrifugation may be performed once or twice. When the number of centrifugations is one, there is an advantage in that scattering particles can be selectively removed while minimizing the deterioration of the physical properties of the quantum dots due to centrifugation. Furthermore, when the number of centrifugations is two, the content of scattering particles in the quantum dot ink composition can be further reduced, and thus, when producing a regenerated quantum dot ink composition in a subsequent process, there is an advantage in that the content of quantum dots and scattering particles can be more precisely controlled.

[0155] If centrifugation is performed twice, the remaining scattering particles remain at a concentration of several ppm, making additional centrifugation unnecessary. As the number of centrifugations increases, ligand desorption from the quantum dots increases, potentially significantly degrading their physical properties. Therefore, it is preferable to perform one or two centrifugations to remove precipitated scattering particles.

[0156] The above centrifugation may be performed at 4000 to 6000 rpm for 10 to 30 minutes, and preferably at 6000 rpm for 10 to 20 minutes. This can be equally applied to the centrifugation in the step described below.

[0157] The content of scattering particles in the quantum dot ink composition from which the scattering particles have been removed may be 400 mg / L or less, preferably 100 mg / L or less, more preferably 40 mg / L or less, and most preferably 20 mg / L or less. When the content of scattering particles in the quantum dot ink composition from which the scattering particles have been removed satisfies the above range, the content of quantum dots and scattering particles can be more precisely controlled when producing a regenerated quantum dot ink composition in a subsequent process, which is preferable because it is easy to manage the quality of the product.

[0158]

[0159] (b) a step of recovering quantum dots from a quantum dot ink composition from which scattering particles have been removed;

[0160] Since the quantum dots in the quantum dot ink composition from which the scattering particles have been removed are dissolved by the solvent mixed in step (a), it is necessary to precipitate the quantum dots from the quantum dot ink composition in order to recover the quantum dots.

[0161] In one embodiment of the present invention, step (b) of the present invention may include a step of selectively precipitating quantum dots by mixing a nonsolvent into the quantum dot ink composition from which the scattering particles have been removed.

[0162] In the present invention, the non-solvent is used to precipitate quantum dots dissolved in the quantum dot ink composition, and means a solvent that has no or very little compatibility with quantum dots, i.e., is insoluble in quantum dots.

[0163] The nonsolvent is not particularly limited as long as it can precipitate quantum dots, and may be appropriately selected depending on the type of solvent mixed in step (a) and the ligand substituted on the surface of the quantum dots to be recovered. It may be preferable to use a solvent having a polarity index of 1 or less as the nonsolvent. Examples of the solvent having a polarity index of 1 or less include cyclohexane, hexane, pentane, heptane, trichloroethylene, etc., and these may be used alone or in combination of two or more. Among these, cyclohexane may be preferably used.

[0164] Quantum dots selectively precipitated from the above quantum dot ink composition can be recovered through centrifugation.

[0165] In one embodiment of the present invention, a non-solvent of 1 to 4 times the weight based on the filtrate of the quantum dot ink composition from which the scattering particles have been removed is mixed and centrifuged once to obtain a solid content, and then a solvent (acetone, etc.) of 0.5 to 2 times the weight based on the obtained solid content is mixed to disperse the solid content, and a non-solvent of 6 to 15 times the weight based on the solid content is mixed thereto and centrifuged once more to recover the quantum dots.

[0166]

[0167] (c) A step of re-substituting the ligand by adding a ligand to the recovered quantum dot.

[0168] Quantum dots recovered from a quantum dot ink composition may have their ligands on the quantum dot surface damaged during steps (a) and (b), and may also be damaged during the disposal of the quantum dot ink composition. When a regenerated quantum dot ink composition is prepared using quantum dots with damaged ligands, the composition's properties, such as viscosity and long-term storage stability, may deteriorate. Therefore, in order to restore the physical properties of the recovered quantum dots, it is necessary to re-modify the surface of the recovered quantum dots.

[0169] In order to re-treat the quantum dot surface, step (c) of the present invention includes a step of re-substituting the ligand by adding a ligand to the quantum dot recovered in step (b).

[0170] The above ligand may include a ligand having 3 to 40 carbon atoms and including a carboxyl group.

[0171] In one embodiment of the present invention, a ligand having 3 to 40 carbon atoms and containing a carboxyl group may be added to the quantum dot recovered in step (b) and reacted at 25 to 100°C for 2 to 7 hours to re-treat the surface of the quantum dot.

[0172] The content of the ligand added in the above step (c) may be 1 to 20 wt%, preferably 1 to 15 wt%, and more preferably 1 to 7 wt%, based on the total weight of the solid content of the recovered quantum dot. When the content of the added ligand satisfies the above range, the surface of the quantum dot can be appropriately re-treated, thereby improving the miscibility, viscosity, and long-term storage stability with respect to the photopolymerizable monomer, which is preferable.

[0173] Quantum dots with surfaces thus reprocessed can be obtained through centrifugation. The centrifugation may be performed once or twice, and preferably once.

[0174] The ligand having 3 to 40 carbon atoms including the above carboxyl group may be a compound represented by the following chemical formula 2.

[0175] [Chemical Formula 2]

[0176]

[0177] In the above chemical formula 2,

[0178] L is a single bond or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkylene group and a substituted or unsubstituted C1 to C20 alkenylene.

[0179] A is a single bond or a C1 to C20 alkylene group or alkenylene group containing at least one functional group selected from the group consisting of ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), sulfonyl (-SO2-), sulfide (-S-), and sulfoxide (-SO-).

[0180] R is hydrogen, or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkyl group and a substituted or unsubstituted C1 to C20 alkenyl group.

[0181] Preferably, in the above chemical formula 2, A may include a functional group selected from ester (-COO-), ether (-O-), or a combination thereof. In addition, A may be a C2 to C15 alkylene group or alkenylene group, preferably a C2 to C10 alkylene group or alkenylene group.

[0182] The compound represented by the above chemical formula 2 may include, but is not limited to, for example, 2-carboxyethyl acrylate, mono-2-(acryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl maleate, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and 2-(2-methoxyethoxy)acetic acid, and the like, and preferably mono-2-(acryloyloxy)ethyl It could be succinate (MAES).

[0183] Meanwhile, the ligand added in the above step (c) may not include a compound represented by the following chemical formula 1.

[0184] [Chemical Formula 1]

[0185]

[0186] In the above chemical formula 1,

[0187] M is a metal of 2 to 4 valence,

[0188] X is an organic group having 3 to 20 carbon atoms,

[0189] n is an integer from 2 to 4.

[0190]

[0191] The compound represented by the above chemical formula 1 may be a metal-thiol compound formed by reacting a metal salt and a thiol compound.

[0192] In the above chemical formula 1, M is a metal having a valence of 2 to 4. For example, M is a metal of group 2 to 14, and may be Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Cd, In, or Sn.

[0193] In the above chemical formula 1, n is determined according to the valence of M and is an integer from 2 to 4.

[0194] In addition, in the above chemical formula 1, X may be an organic group having 3 to 20 carbon atoms. For example, the above X may be an ester (-C(=O)O-), an ether (-O-), a carbonyl (-C(=O)-), a carboxyl group (-C(=O)-OH), a sulfonyl group (-SO2-), a sulfide (-S-), a sulfoxide (-SO-), an alkoxy group (C n H 2n+1 It may be an alkylene group or alkenylene group having 3 to 20 carbon atoms and including at least one functional group selected from the group consisting of an ester (-C(=O)O-) and a hydroxyl group (-OH). Specifically, X may be an organic group having 4 to 15 carbon atoms and including an ester (-C(=O)O-) functional group.

[0195]

[0196] The compound represented by the above chemical formula 1 contains a thiol group. Since the thiol group has excellent affinity for the quantum dot surface, it can improve the dispersibility of the quantum dot in the photopolymerizable monomer. However, if the thiol ligand is excessively substituted, there may be problems such as the generation of a harmful odor, an increase in viscosity, and a decrease in storage stability, making it difficult to apply the quantum dot to an ink composition.

[0197] Therefore, in order to prevent an increase in viscosity of the regenerative quantum dot ink composition and further improve storage stability, it is preferable not to use the compound represented by chemical formula 1, which is a thiol-based ligand, in the ligand re-substitution step.

[0198] The compound represented by the above chemical formula 1 may include, but is not limited to, Zn-(3-methoxybutyl 3-mercaptopropionate)2, Zn-(3-methoxybutyl thioglycolate)2, Zn-(2-ethylhexyl thioglycolate)2, Zn-(butyl mercaptopropionate)2, Zn-(isopropyl mercaptopropionate)2, and Zn-(PEG-Thiol)2, for example.

[0199]

[0200] (d) a step of dispersing the ligand-resubstituted quantum dots in a photopolymerizable monomer;

[0201] The regenerated quantum dot ink composition of the present invention can be manufactured by dispersing the quantum dot whose ligand has been re-substituted in the step (c) in a photopolymerizable monomer, and, if necessary, one or more selected from the group consisting of a photoinitiator, a scattering particle, a polymerization inhibitor, a stabilizer, and other additives can be further added.

[0202] The above photopolymerizable monomer, photoinitiator, scattering particle, polymerization inhibitor, stabilizer and other additives can be applied in the same manner as the contents of the above-described <quantum dot ink composition>.

[0203]

[0204] In one embodiment of the present invention, the content of the ligand-replaced quantum dot may be 1 to 60 wt%, preferably 20 to 50 wt%, based on the total weight of the regenerated quantum dot ink composition.

[0205] In addition, the photopolymerizable monomer may include a (meth)acrylate monomer. The (meth)acrylate monomer may include 1,6-hexanediol diacrylate, which is preferable because the viscosity of the regenerated quantum dot composition can be adjusted to an appropriate level. The content of the photopolymerizable monomer may be 40 to 70 wt%, preferably 50 to 60 wt%, based on the total weight of the regenerated quantum dot ink composition.

[0206]

[0207] When the regenerated quantum dot ink composition of the present invention includes a photoinitiator, the content of the photoinitiator may be 0.01 to 10 wt%, preferably 0.1 to 5 wt%, based on the total weight of the regenerated quantum dot ink composition. When the content of the photoinitiator satisfies the above range, it is preferable because there is an advantage in that the photopolymerization reaction can sufficiently occur without deteriorating the physical properties of the composition.

[0208] In addition, when the regenerated quantum dot ink composition of the present invention includes scattering particles, the content of the scattering particles may be 0.01 to 10 wt%, and preferably 1 to 7 wt%, based on the total weight of the regenerated quantum dot ink composition. When the content of the scattering particles satisfies the above range, it is preferable because there is an advantage of increasing the photoconversion efficiency without deteriorating the physical properties of the composition.

[0209]

[0210] <Regenerative Quantum Dot Ink Composition, Color Filter, and Display Device>

[0211] The present invention provides a regenerated quantum dot ink composition manufactured by a method for manufacturing a regenerated quantum dot ink composition described below.

[0212] The regenerated quantum dot ink composition of the present invention is manufactured by the method for manufacturing the regenerated quantum dot ink composition described above, and the contents of the above-described <quantum dot ink composition> and <method for manufacturing the regenerated quantum dot ink composition> can be equally applied.

[0213]

[0214] The regenerated quantum dot ink composition of the present invention may be a solvent-free type that does not contain a solvent. In addition, the regenerated quantum dot ink composition may be suitable for inkjet printing in an inkjet process.

[0215] The regenerated quantum dot ink composition manufactured by the method for manufacturing the regenerated quantum dot ink composition of the present invention may have a viscosity change of +1.6 cps or less, preferably +0.5 cps or less, compared to the initial viscosity when stored at 50°C for 4 weeks.

[0216] The present invention provides a color filter comprising a cured product of the above-described regenerated quantum dot ink composition. The cured product can be manufactured by including a step of forming a pattern by applying the above-described regenerated quantum dot ink composition onto a substrate using an inkjet spraying method; and a step of curing the pattern.

[0217] The above color filter can be manufactured by methods such as a dyeing method, a pigment dispersion method, a printing method, and an electrodeposition method. In addition, a color filter including a cured product of a regenerated quantum dot ink composition can be manufactured by an ink jet method.

[0218] In addition, the present invention provides a display device including the color filter. The display device may include, but is not limited to, a liquid crystal display (LCD), an electroluminescent display (EL), a plasma display (PDP), a field emission display (FED), an organic light emitting diode (OLED), and the like.

[0219]

[0220] Hereinafter, the present invention will be described in more detail through examples. However, the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention to the examples.

[0221]

[0222] <Example>

[0223] Manufacturing Example 1: Manufacturing of waste quantum dot dispersion 1 from which scattering particles have been removed.

[0224] A waste quantum dot ink composition (HIQ-100G, Hansol Chemical Co., Ltd.) containing green quantum dots (InP / ZnSe / ZnS; ligands: MAES and Zn-(PEG550-Thiol)2; solid content 40 wt%), scattering particles (TiO2, D50 170 nm, solid content 4 wt%), and a photopolymerizable monomer (1,6-hexanediol diacrylate) was prepared. 100 parts by weight of acetone (polarity index 5.1) as a solvent was mixed with 50 parts by weight of the waste quantum dot ink composition, and the precipitated scattering particles were removed through centrifugation (6000 rpm, 15 minutes) (separation once). Afterwards, the filtrate from which the precipitated scattering particles were removed was centrifuged once more (6000 rpm, 15 minutes) (separated twice), thereby producing a waste quantum dot dispersion 1 from which the scattering particles were removed.

[0225] Manufacturing Example 2: Manufacturing of waste quantum dot dispersion 2 from which scattering particles have been removed.

[0226] A waste quantum dot dispersion 2 from which scattering particles were removed was prepared in the same manner as in Manufacturing Example 1, except that ethyl acetate (EA, polarity index 4.4) was mixed instead of acetone as a solvent.

[0227] Manufacturing Example 3: Manufacturing of waste quantum dot dispersion 3 from which scattering particles have been removed.

[0228] A waste quantum dot dispersion 3 from which scattering particles were removed was prepared in the same manner as in Manufacturing Example 1, except that cyclohexyl acetate (CHA, polarity index 4.8) was mixed instead of acetone as a solvent.

[0229] Manufacturing Example 4: Manufacturing of waste quantum dot dispersion 4 from which scattering particles have been removed.

[0230] A waste quantum dot dispersion 4 from which scattering particles were removed was prepared in the same manner as in Manufacturing Example 1, except that isopropyl alcohol (IPA, polarity index 3.9) was mixed instead of acetone as a solvent.

[0231] Manufacturing Example 5: Manufacturing of waste quantum dot dispersion 5 from which scattering particles have been removed.

[0232] A waste quantum dot ink composition (HIQ-200R, Hansol Chemical Co., Ltd.) containing red quantum dots (InP / ZnSe / ZnS; ligands: MAES and Zn-(PEG550-Thiol)2; solid content 36 wt%), scattering particles (TiO2, D50 170 nm, solid content 5 wt%), and a photopolymerizable monomer (1,6-hexanediol diacrylate) was prepared. 100 parts by weight of acetone (polarity index 5.1) as a solvent was mixed with 50 parts by weight of the waste quantum dot ink composition, and the precipitated scattering particles were removed through centrifugation (6000 rpm, 15 minutes) (separation once). Afterwards, the filtrate from which the precipitated scattering particles were removed was centrifuged once more (6000 rpm, 15 minutes) (separated twice), thereby producing a waste quantum dot dispersion 5 from which the scattering particles were removed.

[0233] Manufacturing Example 6: Manufacturing of waste quantum dot dispersion 6 from which scattering particles have been removed.

[0234] A waste quantum dot dispersion 6 from which scattering particles were removed was prepared in the same manner as in Preparation Example 5, except that ethyl acetate (EA, polarity index 4.4) was mixed instead of acetone as a solvent.

[0235] Manufacturing Example 7: Manufacturing of waste quantum dot dispersion 7 from which scattering particles have been removed.

[0236] A waste quantum dot dispersion 7 from which scattering particles were removed was prepared in the same manner as in Manufacturing Example 5, except that cyclohexyl acetate (CHA, polarity index 4.8) was mixed instead of acetone as a solvent.

[0237] Manufacturing Example 8: Manufacturing of waste quantum dot dispersion 8 from which scattering particles have been removed.

[0238] A waste quantum dot dispersion 8 from which scattering particles were removed was prepared in the same manner as in Manufacturing Example 5, except that isopropyl alcohol (IPA, polarity index 3.9) was mixed instead of acetone as a solvent.

[0239]

[0240] Example 1: Preparation of regenerative quantum dot ink composition 1

[0241] 1-1. Recovery of quantum dots

[0242] For the waste quantum dot dispersion 1 from which scattering particles were removed according to the above Manufacturing Example 1, cyclohexane of twice the weight was mixed and centrifuged (6000 rpm, 5 minutes). Based on the solid content obtained through this, acetone of 1 time the weight was mixed and the solid content was dispersed, and then cyclohexane of 12 times the weight based on the solid content was mixed and centrifuged again (6000 rpm, 5 minutes). The solid content obtained through centrifugation was vacuum-dried to obtain quantum dot powder.

[0243] 1-2. Re-processing of the quantum dot surface

[0244] A quantum dot dispersion was prepared by dispersing the quantum dot powder obtained in the above 1-1 in cyclohexyl acetate at a concentration of 20 wt%, and the temperature was raised to 60°C and maintained. Next, 5 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was mixed with 100 parts by weight of the quantum dot dispersion, and stirred for 3 hours under a nitrogen atmosphere. Thereafter, the mixture was cooled to room temperature to complete the reforming reaction of the quantum dot surface.

[0245] 1-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0246] Cyclohexane was mixed into a solution containing quantum dots whose surface was re-polymerized according to the above 1-2, and the resultant quantum dot powder whose surface was re-polymerized was obtained through centrifugation (6000 rpm, 5 minutes). The obtained quantum dot powder was dispersed in 1,6-hexanediol diacrylate at a concentration of 50 wt% to prepare a quantum dot dispersion.

[0247] 1-4. Preparation of regenerative quantum dot ink composition

[0248] A scattering particle dispersion was prepared by dispersing titanium dioxide (TiO2, D50 170 nm) powder in 1,6-hexanediol diacrylate at a concentration of 50 wt%. 80 parts by weight of the quantum dot dispersion prepared in 1-3 above, 8 parts by weight of the scattering particle dispersion, 1 part by weight of TPO-L, and 11 parts by weight of 1,6-hexanediol diacrylate were mixed to prepare a regenerated quantum dot ink composition 1.

[0249] Example 2: Preparation of regenerative quantum dot ink composition 2

[0250] 2-1. Recovery of quantum dots

[0251] Quantum dot powder was obtained using the same method as 1-1 of Example 1 above.

[0252] 2-2. Re-processing of the quantum dot surface

[0253] The re-polymerization reaction of the quantum dot surface was completed using the same method as 1-2 of Example 1 above.

[0254] 2-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0255] Cyclohexane was mixed into a solution containing quantum dots whose surface was re-treated according to the above 2-2, and a solid was obtained through centrifugation (6000 rpm, 5 minutes). After dispersing by mixing acetone in an amount 1 time the weight based on the solid, cyclohexane was mixed, and a quantum dot powder whose surface was re-treated was obtained through centrifugation (6000 rpm, 5 minutes). The obtained quantum dot powder was dispersed in 1,6-hexanediol diacrylate at a concentration of 50 wt% to prepare a quantum dot dispersion.

[0256] 2-4. Preparation of regenerative quantum dot ink composition

[0257] A regenerated quantum dot ink composition 2 was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 2-3 above was used.

[0258] Example 3: Preparation of regenerative quantum dot ink composition 3

[0259] 3-1. Recovery of quantum dots

[0260] Quantum dot powder was obtained using the same method as 1-1 of Example 1 above.

[0261] 3-2. Re-processing of the quantum dot surface

[0262] The repolymerization reaction of the quantum dot surface was completed in the same manner as in 1-2 of Example 1, except that 3 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was used.

[0263] 3-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0264] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 3-2 above was used.

[0265] 3-4. Preparation of regenerative quantum dot ink composition

[0266] A regenerated quantum dot ink composition 3 was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 3-3 above was used.

[0267] Example 4: Preparation of regenerative quantum dot ink composition 4

[0268] 4-1. Recovery of quantum dots

[0269] Quantum dot powder was obtained using the same method as 1-1 of Example 1 above.

[0270] 4-2. Reprocessing of the quantum dot surface

[0271] The repolymerization reaction of the quantum dot surface was completed in the same manner as in 1-2 of Example 1, except that 10 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was used.

[0272] 4-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0273] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 4-2 above was used.

[0274] 4-4. Preparation of regenerative quantum dot ink composition

[0275] A regenerated quantum dot ink composition 4 was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 4-3 above was used.

[0276] Example 5: Preparation of regenerative quantum dot ink composition 5

[0277] 5-1. Recovery of quantum dots

[0278] Quantum dot powder was obtained using the same method as 1-1 of Example 1 above.

[0279] 5-2. Reprocessing of the quantum dot surface

[0280] The repolymerization reaction of the quantum dot surface was completed in the same manner as in 1-2 of Example 1, except that 15 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was used.

[0281] 5-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0282] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 5-2 above was used.

[0283] 5-4. Preparation of regenerative quantum dot ink composition

[0284] A regenerated quantum dot ink composition 5 was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 5-3 above was used.

[0285] Example 6: Preparation of regenerative quantum dot ink composition 6

[0286] 6-1. Recovery of quantum dots

[0287] Quantum dot powder was obtained in the same manner as 1-1 of Example 1, except that the waste quantum dot dispersion 2 from which scattering particles according to Manufacturing Example 2 were removed was used.

[0288] 6-2. Reprocessing of the quantum dot surface

[0289] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that the quantum dot powder obtained in 6-1 above was used.

[0290] 6-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0291] A quantum dot dispersion was prepared in the same manner as 1-3 of Example 1, except that a solution containing quantum dots whose surface had been re-treated according to 6-2 above was used.

[0292] 6-4. Preparation of regenerative quantum dot ink composition

[0293] A regenerated quantum dot ink composition 6 was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 6-3 above was used.

[0294] Example 7: Preparation of regenerative quantum dot ink composition 7

[0295] 7-1. Recovery of quantum dots

[0296] Quantum dot powder was obtained using the same method as 6-1 of Example 6 above.

[0297] 7-2. Reprocessing of the quantum dot surface

[0298] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that the quantum dot powder obtained in 7-1 above was used.

[0299] 7-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0300] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 7-2 above was used.

[0301] 7-4. Preparation of regenerative quantum dot ink composition

[0302] A regenerated quantum dot ink composition 7 was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 7-3 above was used.

[0303] Example 8: Preparation of regenerative quantum dot ink composition 8

[0304] 8-1. Recovery of quantum dots

[0305] Quantum dot powder was obtained in the same manner as 1-1 of Example 1, except that the waste quantum dot dispersion 5 from which scattering particles according to Manufacturing Example 5 were removed was used.

[0306] 8-2. Reprocessing of the quantum dot surface

[0307] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that the quantum dot powder obtained in 8-1 above was used.

[0308] 8-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0309] A quantum dot dispersion was prepared in the same manner as 1-3 of Example 1, except that a solution containing quantum dots whose surface had been re-treated according to 8-2 above was used.

[0310] 8-4. Preparation of regenerative quantum dot ink composition

[0311] A scattering particle dispersion was prepared by dispersing titanium dioxide (TiO2, D50 170 nm) powder in 1,6-hexanediol diacrylate at a concentration of 50 wt%. 72 parts by weight of the quantum dot dispersion prepared in 8-3 above, 10 parts by weight of the scattering particle dispersion, 1 part by weight of TPO-L, and 17 parts by weight of 1,6-hexanediol diacrylate were mixed to prepare a regenerated quantum dot ink composition 8.

[0312] Example 9: Preparation of regenerative quantum dot ink composition 9

[0313] 9-1. Recovery of quantum dots

[0314] Quantum dot powder was obtained using the same method as 8-1 of Example 8 above.

[0315] 9-2. Reprocessing of the quantum dot surface

[0316] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that the quantum dot powder obtained in 9-1 above was used.

[0317] 9-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0318] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface was re-treated according to 9-2 above was used.

[0319] 9-4. Preparation of regenerative quantum dot ink composition

[0320] A regenerated quantum dot ink composition 9 was prepared in the same manner as 8-4 of Example 8, except that the quantum dot dispersion prepared in 9-3 above was used.

[0321] Example 10: Preparation of regenerative quantum dot ink composition 10

[0322] 10-1. Recovery of quantum dots

[0323] Quantum dot powder was obtained using the same method as 8-1 of Example 8 above.

[0324] 10-2. Re-processing of quantum dot surfaces

[0325] The repolymerization reaction of the quantum dot surface was completed in the same manner as in 1-2 of Example 1, except that 3 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was used.

[0326] 10-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0327] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 10-2 above was used.

[0328] 10-4. Preparation of a regenerative quantum dot ink composition

[0329] A regenerated quantum dot ink composition 10 was prepared in the same manner as 8-4 of Example 8, except that the quantum dot dispersion prepared in 10-3 above was used.

[0330] Example 11: Preparation of regenerative quantum dot ink composition 11

[0331] 11-1. Recovery of quantum dots

[0332] Quantum dot powder was obtained using the same method as 8-1 of Example 8 above.

[0333] 11-2. Re-processing of quantum dot surfaces

[0334] The repolymerization reaction of the quantum dot surface was completed in the same manner as in 1-2 of Example 1, except that 10 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was used.

[0335] 11-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0336] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface was re-treated according to 11-2 above was used.

[0337] 11-4. Preparation of a regenerative quantum dot ink composition

[0338] A regenerated quantum dot ink composition 11 was prepared in the same manner as 8-4 of Example 8, except that the quantum dot dispersion prepared in 11-3 above was used.

[0339] Example 12: Preparation of regenerative quantum dot ink composition 12

[0340] 12-1. Recovery of quantum dots

[0341] Quantum dot powder was obtained using the same method as 8-1 of Example 8 above.

[0342] 12-2. Reprocessing of the quantum dot surface

[0343] The repolymerization reaction of the quantum dot surface was completed in the same manner as in 1-2 of Example 1, except that 15 parts by weight of a solution of mono-2-(acryloyloxy)ethyl succinate diluted in cyclohexyl acetate at a concentration of 20 wt% was used.

[0344] 12-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0345] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface was re-treated according to 12-2 above was used.

[0346] 12-4. Preparation of a regenerative quantum dot ink composition

[0347] A regenerated quantum dot ink composition 12 was prepared in the same manner as 8-4 of Example 8, except that the quantum dot dispersion prepared in 12-3 above was used.

[0348] Example 13: Preparation of regenerative quantum dot ink composition 13

[0349] 13-1. Recovery of quantum dots

[0350] Quantum dot powder was obtained in the same manner as 1-1 of Example 1, except that the waste quantum dot dispersion 6 from which scattering particles according to Manufacturing Example 6 were removed was used.

[0351] 13-2. Reprocessing of the quantum dot surface

[0352] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that the quantum dot powder obtained in 13-1 above was used.

[0353] 13-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0354] A quantum dot dispersion was prepared in the same manner as 1-3 of Example 1, except that a solution containing quantum dots whose surface had been re-treated according to 13-2 above was used.

[0355] 13-4. Preparation of a regenerative quantum dot ink composition

[0356] A regenerated quantum dot ink composition 13 was prepared in the same manner as 8-4 of Example 8, except that the quantum dot dispersion prepared in 13-3 above was used.

[0357] Example 14: Preparation of regenerative quantum dot ink composition 14

[0358] 14-1. Recovery of quantum dots

[0359] Quantum dot powder was obtained using the same method as 13-1 of Example 13 above.

[0360] 14-2. Reprocessing of quantum dot surfaces

[0361] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that the quantum dot powder obtained in 14-1 above was used.

[0362] 14-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0363] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 14-2 above was used.

[0364] 14-4. Preparation of a regenerative quantum dot ink composition

[0365] A regenerated quantum dot ink composition 14 was prepared in the same manner as 8-4 of Example 8, except that the quantum dot dispersion prepared in 14-3 above was used.

[0366] Comparative Example 1: Preparation of regenerative quantum dot ink composition a

[0367] 15-1. Recovery of quantum dots

[0368] Quantum dot powder was obtained using the same method as 1-1 of Example 1 above.

[0369] 15-2. Reprocessing of the quantum dot surface

[0370] No re-polymerization reaction was performed on the quantum dot surface.

[0371] 15-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0372] The quantum dot powder obtained in the above 15-1 was dispersed in 1,6-hexanediol diacrylate at a concentration of 50 wt% to prepare a quantum dot dispersion.

[0373] 15-4. Preparation of a regenerative quantum dot ink composition

[0374] A regenerated quantum dot ink composition a was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 15-3 above was used.

[0375] Comparative Example 2: Preparation of regenerative quantum dot ink composition b

[0376] 16-1. Recovery of quantum dots

[0377] Quantum dot powder was obtained using the same method as 1-1 of Example 1 above.

[0378] 16-2. Reprocessing of quantum dot surfaces

[0379] The repolymerization reaction of the quantum dot surface was completed in the same manner as 1-2 of Example 1, except that Zn-(PEG550-Thiol)2 was used instead of mono-2-(acryloyloxy)ethyl succinate.

[0380] 16-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0381] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 16-2 above was used.

[0382] 16-4. Preparation of a regenerative quantum dot ink composition

[0383] A regenerated quantum dot ink composition b was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 16-3 above was used.

[0384] Comparative Example 3: Preparation of regenerative quantum dot ink composition c

[0385] 17-1. Recovery of quantum dots

[0386] Quantum dot powder was obtained using the same method as 8-1 of Example 8 above.

[0387] 17-2. Reprocessing of quantum dot surfaces

[0388] No re-polymerization reaction was performed on the quantum dot surface.

[0389] 17-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0390] The quantum dot powder obtained in the above 17-1 was dispersed in 1,6-hexanediol diacrylate at a concentration of 50 wt% to prepare a quantum dot dispersion.

[0391] 17-4. Preparation of a regenerative quantum dot ink composition

[0392] A regenerated quantum dot ink composition c was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 17-3 above was used.

[0393] Comparative Example 4: Preparation of regenerative quantum dot ink composition d

[0394] 18-1. Recovery of quantum dots

[0395] Quantum dot powder was obtained using the same method as 8-1 of Example 8 above.

[0396] 18-2. Reprocessing of the quantum dot surface

[0397] The re-polymerization reaction of the quantum dot surface was completed in the same manner as 16-2 of Comparative Example 2, except that the quantum dot powder obtained in 18-1 above was used.

[0398] 18-3. Preparation of quantum dot dispersion with completed surface reprocessing

[0399] A quantum dot dispersion was prepared in the same manner as 2-3 of Example 2, except that a solution containing quantum dots whose surface had been re-treated according to 18-2 above was used.

[0400] 18-4. Preparation of a regenerative quantum dot ink composition

[0401] A regenerated quantum dot ink composition d was prepared in the same manner as 1-4 of Example 1, except that the quantum dot dispersion prepared in 18-3 above was used.

[0402]

[0403] <Experimental Example>

[0404] 1. Evaluation of scattering particle sedimentation

[0405] For the waste quantum dot dispersions 1 to 8 from which scattering particles were removed according to Manufacturing Examples 1 to 8, the scattering particle settling property for each solvent was visually evaluated, and the results are shown in Fig. 2.

[0406] Referring to Fig. 2, it can be confirmed that manufacturing examples 1, 2, 5 and 6 using acetone and ethyl acetate (EA) as solvents for precipitating scattering particles selectively precipitate scattering particles and the remaining components are well dispersed to produce a transparent filtrate.

[0407] Additionally, in Manufacturing Examples 3 and 7, which used cyclohexyl acetate (CHA) as a solvent for precipitating scattering particles, it was confirmed that scattering particles were selectively precipitated. However, some scattering particles remained without precipitating, resulting in a somewhat opaque filtrate.

[0408] Meanwhile, Preparation Examples 4 and 8, which used isopropyl alcohol (IPA) as a solvent for precipitation of scattering particles, produced clear filtrates, and precipitates were also observed. However, the significantly greater amount of precipitate compared to the other preparation examples indicates that not only scattering particles but also quantum dots were precipitated.

[0409] From the above results, it can be seen that acetone, ethyl acetate (EA) or cyclohexyl acetate (CHA) can be suitably used as a solvent for precipitating scattering particles from a waste quantum dot ink composition, and acetone or ethyl acetate (EA) can be more suitably used.

[0410]

[0411] 2. Analysis of residual scattering particles

[0412] For the waste quantum dot dispersions 1 to 3 and 5 to 7 from which scattering particles were removed according to Manufacturing Examples 1 to 3 and 5 to 7, the residual amount of scattering particles at the time of the first separation and the second separation was analyzed using ICP-OES (Avio 200, PerkinElmer), and the results are shown in Table 1 below.

[0413]

[0414]

[0415]

[0416] Referring to Table 1 above, it can be confirmed that when acetone and ethyl acetate are used as solvents, the residual amount of scattering particles is 400 ppm (mg / L) or less based on one separation, and the residual amount of scattering particles is 20 ppm (mg / L) or less based on two separations.

[0417]

[0418] 3. Viscosity evaluation

[0419] The viscosity of each of the regenerated quantum dot ink compositions according to Examples 1 to 14 and Comparative Examples 1 to 4 was measured at room temperature (25°C, 100 rpm for 2 minutes) using a viscometer (RheoStress MARS40, HAAKE Co.), and the results are shown in Tables 2 and 3 below.

[0420]

[0421] 4. Evaluation of light absorption rate, quantum efficiency, emission wavelength, and half-width

[0422] The regenerated quantum dot ink compositions according to Examples 1 to 14 and Comparative Examples 1 to 4 were applied to a glass substrate at a thickness of 9 μm using a spin coater (Opticoat MS-A150, Mikasa Co., Ltd.) and exposed to 395 nm UV at 4000 mJ (83°C, 4 s) to produce a cured film. Thereafter, a 2 cm x 2 cm single-film specimen of the produced cured film was loaded into an absolute quantum efficiency measuring device (QE-2100, otsuka electronics), and the light absorption rate, initial quantum efficiency (QE), emission wavelength, and half-width were measured. After heat treatment at 180°C for 30 minutes under a nitrogen atmosphere, the quantum efficiency (Post-Bake QE) was measured. The results are shown in Tables 2 and 3 below.

[0423]

[0424]

[0425] - Reference Example 1: Green quantum dot ink composition (HIQ-100G, Hansol Chemical Co., Ltd.), normal product before disposal

[0426]

[0427]

[0428] - Reference Example 2: Red quantum dot ink composition (HIQ-200R, Hansol Chemical Co., Ltd.), normal product before disposal

[0429]

[0430] Referring to Tables 2 and 3 above, the compositions of Examples 1 to 14 of the present invention, which underwent a step of re-replacing the ligands of quantum dots recovered from the waste quantum dot ink composition, exhibited lower viscosity than Comparative Examples 1 to 4, and exhibited similar levels of light absorption rate, initial quantum efficiency, quantum efficiency after heat treatment, quantum efficiency change rate, emission wavelength, and half-width to those of the normal products, Reference Examples 1 and 2, confirming that the optical properties were also good. In particular, it could be confirmed that the compositions of Examples 1, 6, 8, and 13, which performed only one centrifugation in the quantum dot obtaining process after the ligand re-re-re-re-positioning on the quantum dot surface was completed, exhibited the lowest viscosity and exhibited properties identical to or very similar to those of the normal products.

[0431] In contrast, it can be confirmed that the compositions of Comparative Examples 1 and 3, which omit the step of re-substituting the ligand of the quantum dot recovered from the waste quantum dot ink composition, exhibit higher viscosity than the examples and reference examples.

[0432] In addition, in the case of Comparative Examples 2 and 4, which used thiol-based ligands in the step of re-substituting the ligands of the quantum dots, it can be confirmed that the viscosity actually increases compared to Comparative Examples 1 and 3, which omitted the step of re-substituting the ligands.

[0433]

[0434] 5. Evaluation of high-temperature long-term storage stability

[0435] The regenerated quantum dot ink compositions according to Examples 1, 2, 6 to 9, 13 and 14 and Comparative Examples 1 and 3 were stored in an oven at 50°C, and the viscosities at the initial, 1 week, 2 weeks, 3 weeks and 4 weeks were measured at room temperature (25°C) at 100 rpm for 2 minutes using a viscometer (RheoStress MARS40, HAAKE). The results are shown in Tables 4 and 5 below.

[0436]

[0437]

[0438] - Reference Example 1: Green quantum dot ink composition (HIQ-100G, Hansol Chemical Co., Ltd.), normal product before disposal

[0439]

[0440]

[0441] - Reference Example 2: Red quantum dot ink composition (HIQ-200R, Hansol Chemical Co., Ltd.), normal product before disposal

[0442]

[0443] Referring to Tables 4 and 5 above, it can be confirmed that the compositions of Examples 1, 2, 6 to 9, 13, and 14 do not show a significant increase in viscosity even when stored at 50°C for 4 weeks, indicating excellent long-term storage stability at high temperatures. In particular, it can be confirmed that the compositions of Examples 1, 6, 8, and 13, in which only one centrifugation was performed during the quantum dot obtaining process after the ligand re-polymerization on the quantum dot surface was completed, did not show any particular thickening phenomenon even when stored at 50°C for 4 weeks, indicating that they exhibit properties identical to or very similar to those of the normal product.

[0444] In contrast, the compositions of Comparative Examples 1 and 3, which omit the step of re-substituting the ligand of the quantum dot recovered from the waste quantum dot ink composition, not only have a higher initial viscosity than the examples and reference examples, but also show a significant increase in viscosity when stored at 50°C for 4 weeks.

Claims

1. (a) A step of removing scattering particles from a quantum dot ink composition; (b) a step of recovering quantum dots from the quantum dot ink composition from which the scattering particles have been removed; (c) a step of adding a ligand to the recovered quantum dot to re-substitute the ligand; and (d) A method for producing a regenerated quantum dot ink composition, comprising a step of dispersing the ligand-replaced quantum dot in a photopolymerizable monomer.

2. In claim 1, A manufacturing method, wherein the step (a) comprises a step of selectively precipitating scattering particles by mixing a solvent into the quantum dot ink composition.

3. In claim 2, A manufacturing method wherein the solvent is soluble in the quantum dot included in the quantum dot ink composition.

4. In claim 2, A manufacturing method wherein the solvent has a polarity index of 2.4 to 7.

2.

5. In claim 2, A manufacturing method, wherein the solvent comprises at least one selected from the group consisting of toluene, methyl t-butyl ether, xylene, benzene, diethyl ether, dichloromethane, dichloroethane, butyl acetate, isopropyl alcohol, butanol, tetrahydrofuran, propanol, acetonitrile, acetic acid, dimethylformamide, dimethyl sulfoxide, acetone, ethyl acetate, cyclohexyl acetate, chloroform, 2-butanone, dioxane, methanol, ethanol, and propylene glycol monomethyl ether acetate.

6. In claim 1, A manufacturing method wherein the content of scattering particles in the quantum dot ink composition from which the scattering particles have been removed is 400 mg / L or less.

7. In claim 1, The above step (b) is a manufacturing method including a step of selectively precipitating quantum dots by mixing a nonsolvent into the quantum dot ink composition from which the scattering particles have been removed.

8. In claim 7, A manufacturing method wherein the above non-solvent has a polarity index of 1 or less.

9. In claim 1, A manufacturing method, wherein the ligand comprises a ligand having 3 to 40 carbon atoms and including a carboxyl group.

10. In claim 9, A manufacturing method wherein the ligand having 3 to 40 carbon atoms including the above carboxyl group is a compound represented by the following chemical formula 2. [Chemical Formula 2] (In the above chemical formula 2, L is a single bond or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkylene group and a substituted or unsubstituted C1 to C20 alkenylene, A is a single bond or a C1 to C20 alkylene group or alkenylene group containing at least one functional group selected from the group consisting of ester (-C(=O)O-), ether (-O-), carbonyl (-C(=O)-), sulfonyl (-SO2-), sulfide (-S-), and sulfoxide (-SO-), R is hydrogen or is selected from the group consisting of a substituted or unsubstituted C1 to C20 alkyl group and a substituted or unsubstituted C1 to C20 alkenyl group.) 11. In claim 10, A method for producing a compound represented by the above chemical formula 2, wherein the compound is at least one selected from the group consisting of 2-carboxyethyl acrylate, mono-2-(acryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl succinate, mono-2-(methacryloyloxy)ethyl maleate, 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, and 2-(2-methoxyethoxy)acetic acid.

12. In claim 1, A manufacturing method wherein the above photopolymerizable monomer comprises a (meth)acrylate monomer.

13. In claim 1, A manufacturing method wherein the quantum dot ink composition of step (a) is a waste quantum dot ink composition.

14. A regenerative quantum dot ink composition manufactured by the manufacturing method according to claim 1.

15. Claim 14, A regenerated quantum dot ink composition having a viscosity change of +1.6 cps or less compared to the initial viscosity when stored for 4 weeks at 50°C.

16. In claim 14, A regenerative quantum dot ink composition for inkjet printing.

17. A color filter comprising a cured product of the regenerative quantum dot ink composition according to claim 14.

18. A display device comprising a color filter according to claim 17.

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