JP7318494B2 - Quantum dots, ink compositions and printed matter - Google Patents

Description

TECHNICAL FIELD The present invention relates to quantum dots exhibiting excellent external fluorescence quantum efficiency, ink compositions suitable for inkjet systems, and printed matter.

Quantum dots are extremely small particles (dots) formed to confine electrons in a minute space in order to develop unique optical properties according to quantum mechanics. A single quantum dot has a diameter of 1 nanometer to several tens of nanometers and is composed of approximately 10,000 or less atoms. It has been attracting attention in recent years because the wavelength of emitted fluorescence can be controlled continuously by the size of the particles, and because the wavelength distribution of fluorescence intensity is highly symmetrical and sharp emission can be obtained.
Quantum dots can adjust fluorescence to a wavelength that easily penetrates the human body and can be delivered anywhere in the body, so they are used as light emitting materials for bioimaging, wavelength conversion materials for solar cells without the risk of fading, and electronics and photonics applications. Development into light-emitting materials or wavelength-converting materials as such is being investigated.

When quantum dots are used as a wavelength conversion material, the problem is that the quantum dot layer does not sufficiently absorb the light from the backlight and transmits the light from the backlight, resulting in insufficient light conversion. In order to solve the above problems, a method of diffusing light using scattering has been proposed. It is stated that a Further, Patent Document 2 describes a self-luminous resin composition having excellent sedimentation stability, containing quantum dots using trioctylphosphine as a ligand and inorganic scattering particles.
On the other hand, other than using scattering, a method of enhancing light absorption and light conversion by increasing the concentration of quantum dots in the coating film has been proposed. Optimizing the ligands used to improve compatibility in coatings and compositions is described. For example, Patent Document 3 describes that polyalkylene glycol chains are fixed to semiconductor ultrafine particles to achieve both hydrophilicity and non-specific adsorption to biological substances. In addition, Patent Document 4 describes an inkjet ink excellent in sedimentation separation suppressing property and ejection stability, containing quantum dots, titanium oxide, which is light-scattering particles coated with alumina, and a polymer dispersant. there is

JP 2017-161938 A JP 2016-098375 A JP-A-2002-121549 JP 2018-109141 A

However, in the method described in Patent Document 1, the light wavelength conversion efficiency can be improved by additionally providing the light diffusion layer, but the complexity of the display device itself increases and problems arise in processability.
Further, in the method described in Patent Document 2, since trioctylphosphine is used as a ligand, when an attempt is made to increase the concentration of quantum dots, dispersion stability and inkjet ejection properties become insufficient, resulting in quantum The dot density could not be increased, and the optical properties were insufficient.
In Patent Document 3, the ligand design of the quantum dots achieves compatibility with water, but there is a problem of poor compatibility with solvents. Moreover, Patent Document 3 does not disclose the external conversion efficiency of the coating film.
Further, in the method described in Patent Document 4, a ligand having a long-chain alkyleneoxy group is used, and when an attempt is made to increase the concentration of quantum dots, the dispersion stability and inkjet ejection properties become insufficient, resulting in The concentration of quantum dots could not be increased, and optical properties were insufficient.

That is, the problem of the present invention is to achieve excellent external fluorescence quantum efficiency due to quantum dots exhibiting excellent external fluorescence quantum efficiency, quantum dot concentration is sufficient, furthermore, quantum dots are excellent in dispersion stability, and good inkjet An object of the present invention is to provide an ink composition exhibiting jettability and a printed matter.

The present invention relates to the following inventions [1] to [11].

[1] Quantum dots (A), which are semiconductor fine particles surface-treated with a compound represented by the following general formula (1) and having a molecular weight of 250 or less.
General formula (1): QR ¹ -X-(R ² -O) _n -R ³
[In the general formula (1), Q is a sulfanyl group, an alkylsulfanyl group, or a monovalent heterocyclic group containing a sulfur atom, R ¹ is a direct bond or an alkylene group having 1 to 6 carbon atoms, and X is an ester bond, ^R2 is an ethylene or propylene group, ^R3 is an alkyl group, and n is an integer of 1 or 2. ]

[2] The quantum dot (A) according to [1], wherein the semiconductor fine particles are compound semiconductors.

[3] The quantum dot (A) according to [1] or [2], wherein the semiconductor fine particles are core-shell type, and the shell surface is treated with the compound represented by the general formula (1).

[4] The quantum dot (A) according to any one of [1] to [3], wherein Q in the general formula (1) is a sulfanyl group.

[5] The quantum dot (A) according to any one of [1] to [4], wherein R ¹ in general formula (1) is an alkylene group having 1 to 6 carbon atoms.

[6] The quantum dot (A) according to any one of [1] to [5], wherein the compound represented by the general formula (1) has a molecular weight of 180 to 230.

[7] An ink composition comprising the quantum dots (A) according to any one of [1] to [6] and a solvent (B).

[8] An ink composition comprising the quantum dots (A) according to any one of [1] to [6] and a binder component (C).

[9] The ink composition of [7] or [8], further comprising light scattering particles (D).

[10] The ink composition according to any one of [7] to [9], which is used in an inkjet method.

[11] A printed material formed using the ink composition of any one of [7] to [10].

INDUSTRIAL APPLICABILITY The present invention provides quantum dots exhibiting excellent external fluorescence quantum efficiency, an ink composition that achieves excellent external fluorescence quantum efficiency, has excellent dispersion stability of quantum dots, and exhibits good inkjet ejection properties, and a printed matter. can do.

<Quantum dot (A)>
The quantum dots (A) of the present invention are semiconductor fine particles surface-treated with a compound represented by the following general formula (1). "Surface-treated" means that at least part of the surface of the semiconductor fine particles has the compound, and such a compound present on the surface of the semiconductor fine particles is also called a ligand.
The present invention will be described in detail below. "Parts" and "%" represent "mass parts" and "mass%" unless otherwise specified.

[Semiconductor fine particles]
The semiconductor fine particles are semiconductors mainly composed of inorganic substances, and may be of a single composition, a core-shell type, or a multi-layer structure of three or more layers.
A semiconductor is a group of elements represented by Group 1 elements, Group 2 elements, Group 10 elements, Group 11 elements, Group 12 elements, Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements and Group 17 elements of the periodic table. A semiconductor comprising a compound containing at least two elements selected from Compound semiconductors are more preferred, and compound semiconductors include H, K, Rb, Cs, Cu, Ag, Zn, Cd, Hg, B, Al, Ga, In, Tl, C, Si, Ge, Sn, N, A semiconductor composed of a compound containing at least two elements selected from the group of elements represented by P, As, Sb, Pb, O, S, Se, Te, F, Cl, Br and I, specifically CuCl , CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, MgTe, GaAs, GaP, GaSb, GaN, HgS, HgSe, HgTe, InAs, InP, InSb, InN, AlAs, AlP, AlSb, AlS, PbS, PbSe, Ge , Si _{, CuInS2 , AgInS2 , Si} , Ge, _Pb , InGaP _, CH3NH3PbF3 _{, CH3NH3PbCl3} , _{CH3NH3PbBr3 , CH3NH3PbI3 , CsPbF3} , _CsPbCl3 , CsPbBr ₃ , CsPbI ₃ , RbPbF ₃ , RbPbCl ₃ , RbPbBr 3 , RbPbI ₃ , KPbF ₃ , KPbCl ₃ , KPbBr ₃ , KPbI ₃ and _the like. More preferably H, K, Rb, Cs, Cu, Ag, Zn, B, Al, Ga, In, C, Si, Ge, Sn, N, P, O, S, Te, Cl, Br and I A semiconductor composed of a compound containing at least two elements selected from the element group shown.
For applications that emit visible light, a semiconductor containing In as a constituent element is more preferable because of its narrow bandgap.

A core-shell type semiconductor fine particle has a structure in which a core structure is covered with a semiconductor composed of a component different from that of the semiconductor forming the core. By making the shell a semiconductor with a large bandgap, excitons (electron-hole pairs) generated by photoexcitation are confined within the core. As a result, the probability of non-radiative transition on the surface of the semiconductor fine particles is reduced, and the quantum efficiency of light emission and the stability of the fluorescence properties of the semiconductor quantum dots are improved, which is preferable.

The average particle size of the semiconductor fine particles including the core and shell is preferably 0.5 nm to 100 nm, and the particle size can be selected so that desired color development can be obtained. In the case of the core-shell type, one semiconductor fine particle may contain a plurality of shell fine particles. The average particle size of the semiconductor fine particles in the case of a single semiconductor composition and the average particle size of the core-shell type core are preferably 0.5 nm to 10 nm. An average particle diameter of 0.5 nm or more is preferable in terms of synthesis, and an average particle diameter of 10 nm or less is preferable because the quantum confinement effect is improved and desired fluorescence can be easily obtained.
Also, the quantum dots preferably have an average particle size of 2 nm to 1 μm. The shape of the quantum dots is not limited to spherical, but may be rod-like, disk-like, or other shapes.

The average particle size referred to here refers to a value obtained by observing the semiconductor fine particles with a transmission electron microscope, randomly measuring the size of 30 particles, and adopting the average value thereof. At this time, since the semiconductor fine particles are accompanied by ligands, which will be described later, a scanning transmission electron microscope accompanied by energy dispersive X-ray analysis is used to identify the semiconductor material portion, and then the electron density in the transmission electron microscope image. Due to the difference, the particle size is measured using the fact that the semiconductor fine particle portion is imaged darkly for the ligand described later.

[Compound represented by formula (1)]
General formula (1): QR ¹ -X-(R ² -O) _n -R ³
[In the general formula (1), Q is a sulfanyl group, an alkylsulfanyl group, or a monovalent heterocyclic group containing a sulfur atom, R ¹ is a direct bond or an alkylene group having 1 to 6 carbon atoms, and X is an ester bond, ^R2 is an ethylene group or propylene group, ^R3 is an alkyl group, n is an integer of 1 or 2, and the molecular weight of the compound represented by general formula (1) is 250 or less. be. ]

Examples of sulfur atom-containing monovalent heterocyclic groups for Q include thienyl, tetrahydrothienyl, thianyl, thiazolyl and thiazinyl groups. These may be substituted with an alkyl group having 1 to 6 carbon atoms. More preferably, it is a thienyl group or a thianyl group.

The substituent Q in the general formula (1) is preferably a sulfanyl group, an alkylsulfanyl group, a thienyl group or a thianyl group, more preferably a sulfanyl group.

Examples of the alkyl group in the alkylsulfanyl group for Q include linear alkyl groups such as methyl, ethyl and hexyl groups. A portion of the hydrogen in the alkyl group may be eliminated to form a double bond, or may form a ring. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is particularly preferable.

Examples of the alkyl group for R ³ include straight-chain alkyl groups such as a methyl group, an ethyl group, and a hexyl group, and the alkyl group may be substituted with an alkyl group having 1 to 3 carbon atoms. Partial hydrogen may be dropped to form a double bond or a ring. An alkyl group having 1 to 4 carbon atoms is preferred, an alkyl group having 1 to 2 carbon atoms is more preferred, and a methyl group is particularly preferred.

R ¹ is preferably an alkylene group having 1 to 6 carbon atoms. The alkylene group having 1 to 6 carbon atoms in R ¹ includes methylene group, ethylene group, propylene group and the like, preferably an alkylene group having 2 or 3 carbon atoms, more preferably an ethylene group.
Moreover, it is preferable that n is two.

From the viewpoint of improving the content ratio of quantum dots and ensuring compatibility, the molecular weight of the compound represented by general formula (1) is 250 or less, preferably 100 to 250, more preferably 150 to 250. It is preferably 180-230.

Specific examples of the compounds represented by formula (1) are shown in Tables 1 to 4 below.

The quantum dots (A) may be surface-treated with another known ligand in addition to the compound represented by general formula (1). Moreover, you may use together the well-known quantum dot surface-treated by well-known ligands other than the compound represented by General formula (1).

<Ink composition>
The quantum dots of the present invention can be made into an ink composition by further including a solvent (B) and/or a binder component (C).

<Solvent (B)>
The solvent (B) is preferably an organic solvent, and it is preferable to use an organic solvent commonly used in inkjet inks. In general, organic solvents used in inkjet inks have high solubility in resins that may be contained in the inkjet inks, which will be described later, and swell printer members that come into contact with the ink when the inks are ejected from the inkjet printer. It is preferable to use a solvent that has little action and the viscosity of the solvent is as low as possible. The organic solvent is selected from the viewpoints of solubility in the resin, swelling action on the printer member, viscosity, and drying property of the ink in the nozzle, and is selected from the group consisting of alcohol-based solvents, glycol-based solvents, ester-based solvents, and ketone-based solvents. It is preferable that at least one organic solvent selected from is included. These can be used alone or in combination of two or more.

Examples of alcohol solvents include hexanol, heptanol, octanol, nonanol, decanol, undecanol, cyclohexanol, benzyl alcohol, amyl alcohol, and the like.

Examples of glycol solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, methoxymethoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol. Monobutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol isopropyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 1-butoxyethoxypropanol, 1-methoxy-2-propyl acetate, and the like.

Examples of ester-based solvents include ethyl lactate, propane lactate, and butyl lactate.

Examples of ketone-based solvents include cyclohexanone, ethyl amyl ketone, diacetone alcohol, diisobutyl ketone, isophorone, methylcyclohexanone, and acetophenone.

The solvent (B) is solvent (S-1) or solvent (S-2) represented by the following general formula from the viewpoint of viscosity, drying property of ink in nozzles, solubility of contained components, and swelling action on device members. and at least one selected from the group consisting of solvents (S-3) having two or more acetate structures and having a boiling point at 760 mmHg of 120° C. to 260° C., preferably 170° C. or higher. .
Solvent (S-1): R ¹⁸ —(OC ₂ H ₄ ) _m —OC(=O)—CH ₃
[In the general formula, R ¹⁸ is an alkyl group having 1 to 8 carbon atoms, C ₂ H ₄ is a linear or branched ethylene chain, and 1≦m≦3. ]
Solvent (S-2): R ¹⁹ —(OC ₃ H ₆ ) _p —OC(=O)—CH ₃
[In the general formula, R ¹⁹ is an alkyl group having 1 to 8 carbon atoms, C ₃ H ₆ is a linear or branched propylene chain, and 1≦p≦3. ]

Specific examples of the solvents (S-1) to (S-3) include propylene glycol methyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol diacetate, 1, Examples include 3-butylene glycol diacetate, 1,6-hexanediol diacetate, triacetin, etc., but are not necessarily limited thereto. Among them, propylene glycol methyl ether acetate and diethylene glycol monobutyl ether acetate are preferred from the viewpoint of ejection stability.

From the viewpoint of the ejection stability and the drying property of the ink in the nozzle, it is preferable that the solvent (B) contains 60% by mass or more of an organic solvent having a boiling point of 170° C. or higher at 760 mmHg.

The SP value of the solvent is preferably 8-13. In the present invention, the SP value can be calculated by Fedors' estimation method calculated from the molecular structure.

<Binder component (C)>
A resin (C1) or a polymerizable compound (C2) can be used as the binder component (C).

[Resin (C1)]
As the resin, either a thermosetting resin or a thermoplastic resin can be used. Polyester resin, amino resin, vinyl resin, butyral resin, linear olefin resin, aromatic polyether resin, polyimide resin, fluorene polycarbonate resin, fluorene polyester resin, polycarbonate resin, polyamide (aramid) resin, polyarylate resin, polysulfone resin, polyether sulfone resin, polyparaphenylene resin, polyamideimide resin, polyethylene naphthalate (PEN) resin, fluorinated aromatic polymer resin, epoxy resin, allyl ester curable resin, silsesquioxane ultraviolet curable resin, and the like. .
The resin can be appropriately selected depending on the coating method, printing method, and base material. Among them, acrylic resin is preferable from the viewpoint of affinity with the treatment agent.

Specifically as the resin, BR-50, BR-52, MB-2539, BR-60, BR-64, BR-73, BR-75, MB-2389, BR-80, BR- manufactured by Mitsubishi Rayon Co., Ltd. 82, BR-83, BR-84, BR-85, BR-87, BR-88, BR-90, BR-95, BR-96, BR-100, BR-101, BR-102, BR-105, BR-106, BR-107, BR-108, BR-110, BR-113, MB-2660, MB-2952, MB-3012, MB-3015, MB-7033, BR-115, MB-2478, BR- 116, BR-117, BR-118, BR-122, ER-502, Wilbur-Ellis A-11, A-12, A-14, A-21, B-38, B-60, B -64, B-66, B-72, B-82, B-44, B-48N, B-67, B-99N, DM-55, BASF JONCRYL67, JONCRYL678, JONCRYL586, JONCRYL611, JONCRYL680, JONCRYL682 , JONCRYL683, JONCRYL690, JONCRYL819, JONCRYL JDX-C3000, JONCRYL JDX-C3080, Solbin resin CL, CNL, C5R, TA3, TA5R manufactured by Nissin Chemical Industry Co., Ltd. Vinyl resin E15/45, H14/36, H40 manufactured by Wacker /43, E15/45M, E15/40M, Super Ester 75 manufactured by Arakawa Chemical Co., Ltd., Estergum HP, Malkid 33, YS Polyster T80 manufactured by Yasuhara, Hiretts HRT200X manufactured by Mitsui Chemicals, SMA2625P manufactured by Sartomer, Toyobo DIC's Vylon series, DIC's Polylight series, Ube Industries' polyester polyol series, Tosoh's NIPPOLAN series, ADEKA's ADEKA New Ace series, ADEKA polyether series, AGC's EXENOL series, Daiichi Kogyo Seiyaku Co., Ltd. Poly Hardener, DK Flex, DK Polyol, Hard Master, Sanyo Kasei Prime Pole Series, Taisei Fine Chemical 6000 Series, Mitsubishi Chemical jER828, jER825, jER834, jER1001, jER1002, jER1009, jER1010, jER806, jER807, jER4005P , jER4007P, jER4010P, jER1256, jER152, jER154, jER157S70, 1031S, Kaneka Zemlak, and the like.
The above resins may be used alone, or two or more of them may be used in combination.

The weight average molecular weight (Mw) of the resin is preferably 1,000 to 50,000, and particularly preferably 3,000 to 45,000 for stable ejection of the ink composition from the inkjet head. When the weight-average molecular weight is 1,000 or more, the printed matter has sufficient coating film resistance, and when the weight-average molecular weight is 50,000 or less, ink-jet head clogging is less likely to occur, resulting in good dischargeability. The mass average molecular weight Mw can be obtained as a styrene equivalent molecular weight by gel permeation chromatography.

[Curing agent]
When the binder component (B) contains a resin, a curing agent may be used together. When a curing agent is used together, the curing agent is included in the binder component.
Examples of curing agents include those that react with functional groups in resins to form crosslinks between molecules, such as amine compounds, isocyanate compounds, polyol compounds, carboxylic acid compounds, acrylate monomers, carbodiimide compounds, and epoxy compounds. , oxetane compounds, phenol compounds, benzoxazine compounds, and silane coupling agents.

As the cross-linking system to be formed, an amino group-epoxy cross-linking system, a urethane bond cross-linking system, an alkoxysilane cross-linking system, an ester group cross-linking system, or a composite cross-linking system in which two or more of these are combined is preferably used.

Specific examples of the amino group-epoxy crosslinked system include a combination of a bifunctional or higher functional amine compound and a bifunctional or higher functional epoxy compound, for example, an epoxy resin and a bifunctional or higher functional amine compound. As a specific example of the urethane bond cross-linking system, a combination of a polyol compound and a polyisocyanate compound includes, for example, a polyol resin and a bifunctional or higher isocyanate compound. Specific examples of alkoxysilane cross-linking systems include moisture-curing systems of alkoxysilyl group-pendant acrylic resins. Specific examples of the ester group cross-linking system include a combination of a carboxyl group-pendant acrylic compound or a carboxyl group-pendant polyester, and a bifunctional or more functional epoxy compound. mentioned.

Examples of difunctional or higher amine compounds include chain aliphatic polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenediamine and diethylaminopropylamine; N-aminoethylpiperazine, di(4-amino-3 Cycloaliphatic polyamines such as -methylcyclohexyl)methane, Araldit HY-964, menzenediamine, isophoronediamine, S Cure 211, S Cure 212, di(4-aminocyclohexyl)methane or 1,3-aminomethylenecyclohexane; Aliphatic aromatic amines such as xylylenediamine, xylylenediamine trimer, xylylenediamine derivatives and xylylene derivatives; aromatic amines such as melamine, benzoguanamine, metaphenylenediamine, diaminodiphenylmethane or diaminodiphenylsulfone; These can be used singly or in combination of two or more.

Commercially available isocyanate compounds include, for example, Barnock series manufactured by DIC, Takenate series manufactured by Mitsui Chemicals, Coronate series manufactured by Tosoh, and Millionate series.

Examples of carboxyl group-pendant acrylic compounds include copolymers of (meth)acrylic acid and copolymerizable (meth)acrylic monomers.
The carboxyl group-pendant polyester includes, for example, an addition reaction product of a compound having two acid anhydride groups and a diol. Examples of the compound having two acid anhydride groups include ethylene glycol bis-anhydro trimellitate, glycerin bis-anhydro trimellitate monoacetate, benzophenonetetracarboxylic dianhydride, pyromellitic anhydride, 4, 4′-biphthalic anhydride and the like, and diols include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, neopentyl glycol, cyclohexanediol, cyclopentanediol and the like. It can be synthesized according to the polyester synthesis method.

[Polymerizable compound (C2)]
As the polymerizable compound, a polymerizable monomer that is polymerized by light irradiation or heat can be used, and a photopolymerizable monomer is preferable. The photopolymerizable monomer that can be used is not particularly limited, and may be a photoradical polymerizable monomer or a photocationically polymerizable monomer. Monofunctional monomers and polyfunctional monomers may be used alone or in combination. good too.

(Photoradical polymerizable monomer)
Specific examples of photoradical polymerizable monomers include monofunctional monomers such as benzyl (meth)acrylate, (ethoxylated (or propoxylated)) 2-phenoxyethyl (meth)acrylate, dicyclopentenyl (oxyethyl) (meth)acrylate, phenoxy diethylene glycol (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, methoxydipropylene glycol (meth) acrylate, Dipropylene glycol (meth)acrylate, β-carboxylethyl (meth)acrylate, trimethylolpropane formal (meth)acrylate, isoamyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate ) acrylate, dicyclopentanyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 1,4-cyclohexanedimethanol (meth)acrylate, 2 - hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, acrylamide (meth)acrylate, acryloylmorpholine, N-vinylcaprolactam, N-vinylpyrrolidone, N-vinylformamide, Various acrylic acid esters such as N-acryloyloxyethylhexahydrophthalimide, ester acrylate, methylolated melamine (meth)acrylate, epoxy (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and urethane acrylate, and Methacrylic acid ester, (meth)acrylic acid, styrene, vinyl acetate, hydroxyethyl vinyl ether, (meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-vinylformamide, acrylonitrile and the like.

Photoradical polymerizable polyfunctional monomers include dimethyloltricyclodecane di(meth)acrylate, (ethoxylated (or propoxylated)) bisphenol A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, (poly) Ethylene glycol di(meth)acrylate, (ethoxylated (or propoxylated)) 1,6-hexanediol di(meth)acrylate, (ethoxylated (or propoxylated)) neopentyl glycol di(meth)acrylate, neopentyl hydroxypivalate glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, (neopentyl glycol-modified) trimethylolpropane di(meth)acrylate, tripropylene glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, Pentaerythritol tri (or tetra) (meth) acrylate, trimethylolpropane tri (or tetra) (meth) acrylate, tetramethylolmethane tri (or tetra) (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerin di ( meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, tricyclodecanyl(meth)acrylate, hydroxyethyl vinyl ether, pentaerythritol trivinyl ether and the like.

(Photo cationic polymerizable monomer)
Specific examples of photocationically polymerizable monomers include monofunctional monomers such as glycidyl methacrylate, 2-ethylhexyloxetane, 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, and 3-hydroxymethyl-3. -propyloxetane, 3-hydroxymethyl-3-n-butyloxetane, 3-hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl- 3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane, 3-hydroxyethyl-3-
phenyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl-3-phenyloxetane, 3-hydroxybutyl-3-methyloxetane and the like.

Examples of photocationically polymerizable polyfunctional monomers include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, phenol novolac type epoxy compounds, trimethylolpropane glycidyl ether, neopentyl glycol diglycidyl ether, 1,2-epoxy-4- vinylcyclohexane, 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane, xylylene bisoxetane, 3-ethyl-3 {[(3-ethyloxetane- 3-yl)methoxy]methyl}oxetane and the like.

From the viewpoint of curability, the content of the polymerizable compound (C2) is preferably 5 to 80% by mass based on the total solid content of the ink composition.

[Polymerization initiator]
When the binder component (B) contains a polymerizable compound, it is preferable to use a polymerization initiator together. Examples of the polymerization initiator include photopolymerization initiators and thermal polymerization initiators, and one of them can be used alone, or two or more of them can be used in combination at an arbitrary ratio as necessary. In addition, when using a polymerization initiator together, a polymerization initiator is regarded as a binder component.

When the binder component (B) contains a photopolymerizable compound, it is preferable to use a photopolymerization initiator together. The photopolymerization initiator may be a photoradical polymerization initiator or a photocationic polymerization initiator, and the type thereof is not limited. By including a photopolymerization initiator, an ink layer formed from the ink composition can be cured by ultraviolet irradiation.

(Photoradical polymerization initiator)
Photoradical polymerization initiators include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1 -hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]- Acetophenone compounds such as 1-[4-(4-morpholinyl)phenyl]-1-butanone or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one; benzoin, Benzoin compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, or benzyl dimethyl ketal; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4 Benzophenone compounds such as '-methyldiphenyl sulfide or 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2, Thioxanthone compounds such as 4-diisopropylthioxanthone or 2,4-diethylthioxanthone; 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2- (p-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, 2-piperonyl-4,6 -bis(trichloromethyl)-s-triazine, 2,4-bis(trichloromethyl)-6-styryl-s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s -triazine, 2-(4-methoxy-naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, or 2,4 -triazine compounds such as trichloromethyl-(4'-methoxystyryl)-6-triazine; 1,2-octanedione, 1-[4-(phenylthio)phenyl-,2-(O-benzoyloxime)], or Oxime ester compounds such as ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); bis(2,4,6) -trimethylbenzoyl)phenylphosphine oxide or phosphine compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; quinone compounds such as 9,10-phenanthrenequinone, camphorquinone, and ethylanthraquinone; borate compounds; carbazole-based compounds; imidazole-based compounds; or titanocene-based compounds.

Commercially available acetophenone compounds include "Omnirad 907" (2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one) manufactured by IGM Resins B.V., " Omnirad 369" (2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone), "Omnirad 379" 2-benzyl-2 -dimethylamino-1-(4-morpholinophenyl)-butan-1-one and the like.
Further, commercially available phosphine compounds include "Omnirad 819" (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide) and "Omnirad TPO H" (2,4 , 6-trimethylbenzoyldiphenylphosphine oxide) and the like.

(Photo cationic polymerization initiator)
Photocationic polymerization initiators include iodonium salts such as diphenyliodonium hexafluorophosphate, 4-isopropyl-4'-methyldiphenyliodonium tetrakis(pentafluorophenyl)borate, tri-p-tolylsulfonium hexafluorophosphate, triphenyl Sulfonium salts such as sulfonium tetrafluoroborate are included.

Commercially available iodonium salt compounds include "WPI-113" (bis[4-(alkylC10-C13)phenyl]iodonium hexafluorophosphate) and "WPI-116" (bis [4-(alkylC10-C13)phenyl]iodonium hexafluoroantimonate), “WPI-169” (bis[4-tert-butylphenyl]iodonium bisperfluorobutanesulfonylimide), “WPI-170” bis[4- tert-butylphenyl]iodonium hexafluorophosphate), "WPI-124" (bis[4-(alkylC10-C13)phenyl]iodonium tetrakispentafluorophenylborate), and the like.
Commercially available sulfonium salt compounds include CPI-100P (triarylsulfonium hexafluorophosphate), CPI-101A (triarylsulfonium hexafluoroantimonate), and CPI-310BP (triarylsulfonium tetrakispenta) manufactured by San-Apro Co., Ltd. fluorophenylborate), and "Irgacure 290" (tetrakispentafluorophenylborate) manufactured by BASF Corporation.

A photoinitiator may be used individually by 1 type or in mixture of 2 or more types by arbitrary ratios as needed.

Thermal polymerization initiators include, for example, thermal radical polymerization initiators, thermal cationic polymerization initiators, thermal anionic polymerization initiators, or mixtures thereof.
Examples of thermal radical polymerization initiators include peroxides and azo compounds, and polymeric azo initiators composed of polymeric azo compounds can also be used.
Examples of polymeric azo initiators include those having a structure in which a plurality of units such as polyalkylene oxide and polydimethylsiloxane are bonded via an azo group. As the polymer azo initiator having a structure in which a plurality of units such as polyalkylene oxide are bonded via the azo group, for example, a polycondensate of 4,4'-azobis (4-cyanopentanoic acid) and polyalkylene glycol and polycondensates of 4,4′-azobis(4-cyanopentanoic acid) and polydimethylsiloxane having terminal amino groups.
Examples of peroxides include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, and peroxydicarbonates.

Examples of commercially available thermal radical polymerization initiators include Perbutyl O, Perhexyl O, Perbutyl PV (all manufactured by NOF Corporation), V-30, V-501, V-601, VPE-0201, VPE-0401, and VPE-0601 (both manufactured by Wako Pure Chemical Industries, Ltd.).

Examples of thermal cationic polymerization initiators include various onium salts such as quaternary ammonium salts, phosphonium salts, and sulfonium salts. Commercially available products of the above thermal cationic polymerization initiators include, for example, Adeka Opton CP-66, Adeka Opton CP-77 (all manufactured by ADEKA), San Aid SI-60L, San Aid SI-80L, and San Aid SI-100L (all of Sanshin Kagaku Kogyo Co., Ltd.), CI series (manufactured by Nippon Soda Co., Ltd.), and the like.

<Light scattering particles (D)>
The ink composition of the present invention can contain light scattering particles (D). By scattering light in the light conversion layer with the light scattering particles (D), light absorption can be increased in addition to the quantum dots (A) and the solvent (B). Light scattering particles include inorganic light scattering particles (D1) or organic light scattering particles (D2).

<Inorganic light scattering particles (D1)>
Metal oxide fine particles include titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), cerium oxide (CeO ₂ ), hafnium oxide (HfO ₂ ), niobium pentoxide (Nb ₂ O ₅ ), tantalum pentoxide (Ta ₂ O ₅ ), indium oxide (In ₂ O ₂ ), tin oxide (Sn ₂ O ₂ ), indium tin oxide (ITO), and zinc oxide (ZnO). particles. Among them, particles of titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), and zinc oxide (ZnO) are preferable, and titanium oxide (TiO ₂ ) particles are preferable from the viewpoint of translucency, dispersibility, weather resistance, and light resistance. Especially preferred.

The titanium oxide (TiO ₂ ) is not particularly limited, and titanium oxide (TiO ₂ ) previously surface-treated may be used. Surface treatment can stabilize dispersion and improve weather resistance. Any known surface treatment method or surface treatment agent can be used.

Specific examples of titanium oxide include "Tipaque CR-50, 50-2, 57, 80, 90, 93, 95, 953, 97, 60, 60-2, 63, 67, 58, 58- 2, 85" "Tipake R-820, 830, 930, 550, 630, 680, 670, 580, 780, 780-2, 850, 855" "Tipake A-100, 220" "Tipake W-10" "Tipake PF-740, 744" "TTO-55 (A), 55 (B), 55 (C), 55 (D), 55 (S), 55 (N), 51 (A), 51 (C)" " TTO-S-1, 2", "TTO-M-1, 2", Tayca's "Titanics JR-301, 403, 405, 600A, 605, 600E, 603, 805, 806, 701, 800, 808" "Titanics JA-1, C, 3, 4, 5", "Titanics MT-01, 10EX, 05, 100S, 100TV, 100Z, 150EX, 150W, 100AQ, 100WP, 100SA, 100HD, 300HD, 500HD, 500B , 500SA, 500SAS, 600B, 600SA, 700B, 700HD, MTY-02, 110M3S, 700BS, JMT-150IB, 150AO, 150FI, 150ANO", DuPont "Taipur R-900, 902, 960, 706, 931" etc. is mentioned.

From the viewpoint of redispersibility in the ink composition, it is preferable that there is no strong aggregation between particles. Therefore, the average particle diameter of the metal oxide fine particles is preferably 100 nm or less, more preferably 30 nm or more and 100 nm or less, and particularly preferably 50 nm or more and 100 nm or less. When the content is within the above range, aggregation between particles can be prevented, and an ink composition having excellent redispersibility can be provided. Moreover, by setting it within the above range, the excitation light transmittance can be further suppressed, and the external quantum efficiency can be improved.

<Organic Light Scattering Particles (D2)>
The organic light-scattering particles (D2) are fine particles composed of an organic component, and the shape thereof is not particularly limited. By using the spherical organic light-scattering particles, the backlight is scattered, the quantum dots (A) are sufficiently excited, and the luminous efficiency of the printed matter obtained from the ink composition can be further enhanced.

Examples of organic fine particles include silicone-based fine particles, melamine-based resin fine particles, melamine-benzoguanamine-based resin fine particles, acrylic resin fine particles (for example, polymethylmethacrylate-based fine particles (hereinafter referred to as PMMA-based fine particles), acrylic-styrene copolymer fine particles, Coalesced fine particles, polycarbonate-based fine particles, polyethylene-based fine particles, polystyrene-based fine particles, benzoguanamine-based resin fine particles, etc. These may be used alone or in combination of two or more.

Specific examples of silicone-based fine particles include KMP-594, KMP-597, KMP-598, KMP-600, KMP-601, KMP-602 (manufactured by Shin-Etsu Chemical Co., Ltd.), Torefil E-506S, EP-9215 ( manufactured by Dow Corning Toray Co., Ltd.) and the like.

Specific examples of the melamine-based resin fine particles include Eposter SS, Eposter S, Eposter FS, Eposter S6, and Eposter S12 (manufactured by Nippon Shokubai Co., Ltd.).
A specific example of the melamine-benzoguanamine resin particles is Eposter M30 (manufactured by Nippon Shokubai Co., Ltd.).

Specific examples of acrylic resin fine particles include Eposter MA1002, Eposter MA1004, Eposter MA1006, Eposter MA1010 (manufactured by Nippon Shokubai Co., Ltd.), Tuftic FH-S005, Tuftic FH-S008, Tuftic FH-S010, Tuftic FH-S015, and Tuftic. FH-S020 (manufactured by Toyobo Co., Ltd.), Chemisnow MX-80HwT, MX-150, MX-180TA, MX-300, MX-500, MX-1000, MX-1500H, MX-2000, MX-3000 (Soken Chemical Co., Ltd.) manufactured by the company).

Specific examples of acrylic-styrene copolymer fine particles include Eposter MA2003 (manufactured by Nippon Shokubai Co., Ltd.), FS-102, FS-201, FS-301, MG-451, MG-351, (Nippon Paint Industrial Coating manufactured by Sus Co., Ltd.) and the like.

Specific examples of polycarbonate-based fine particles include fine particles described in JP-A-2014-125495, fine particles obtained by the production method described in JP-A-2011-26471, and fine particles obtained by the method described in JP-A-2001-213970. etc.

Specific examples of polyethylene-based fine particles include Miperon XM-220, XM221U (manufactured by Mitsui Chemicals, Inc.), and Flowbeads LE-1080 (manufactured by Sumitomo Seika Chemicals, Inc.).
Specific examples of polystyrene fine particles include Chemisnow SX-130H, SX-350H, and SX-500H (manufactured by Soken Chemical Co., Ltd.).

Specific examples of benzoguanamine-based resin fine particles include Eposter MS, Eposter M05, and Eposter L15 (manufactured by Nippon Shokubai Co., Ltd.).

Further, as the organic light scattering particles (D2), acrylic resin fine particles containing fluorine substituents can be used. Examples of such fluorine-substituted acrylic resin fine particles include fluorine-substituted polymethyl methacrylate fine particles, fluorine-substituted acrylic-styrene copolymer fine particles, fluorine-substituted polycarbonate fine particles, and polyvinyl fluoride fine particles. etc. Containing fluorine prevents agglomeration between particles and facilitates redispersibility after sedimentation. Furthermore, by containing a fluorine group, it is possible to lower the refractive index than the binder component containing the quantum dots (A), and it is possible to further improve the luminous efficiency in combination with the scattering effect, which is preferable.

Although the average particle size of the organic light scattering particles (D2) is not particularly limited, it is preferably 100 nm or more and 1000 nm or less. By being in the above range, a sufficient scattering effect can be exhibited. Furthermore, even if the scattering intensity (haze value) is small, the scattering angle is widened, so scattering effective for total reflection can be obtained, and the scattering effect inside the coating film is enhanced, which is preferable because the light efficiency is improved. The average particle size and particle size distribution of the organic light-scattering particles (D2) can be adjusted by adjusting synthesis conditions such as polymerization temperature and polymerization composition.

The light-scattering particles (D) are preferably used as a dispersion from the viewpoint of suppressing sedimentation in the ink composition. The dispersion can be obtained by dispersing using a dispersant suitable for the surface condition of the light scattering particles (D). Further, the average particle size and particle size distribution of the light scattering particles (D) can be adjusted by changing the conditions such as the disperser, dispersion medium, dispersion time or dispersant.
Dispersers include paint conditioners (manufactured by Red Devil), ball mills, sand mills ("Dyno Mill" manufactured by Shinmaru Enterprises, etc.), attritors, pearl mills ("DCP Mill" manufactured by Eirich, etc.), coball mills, homomixers, Homogenizer (M Technic "CLEARMIX" etc.), Wet jet mill (Jenus PY", Nanomizer "Nanomizer"), Micro Bead Mill (Kotobuki Kogyo Co., Ltd. "Super Apec Mill" and "Ultra Apec Mill"), etc. can be used. When media are used in the disperser, it is preferable to use glass beads, zirconia beads, alumina beads, magnetic beads, polystyrene beads, or the like. Dispersion may be carried out stepwise using two or more types of dispersers or two or more types of media with different sizes.

The content of the light scattering particles (D) is preferably 2 to 20% by mass, more preferably 5 to 12.5% by mass, based on the total amount of the ink composition of the present invention. By adjusting the amount within the above range, the ink composition can be used without causing poor compatibility. When the content is 2% by mass or more, excellent sedimentation stability of the ink composition can be exhibited, and a sufficient scattering effect can be obtained, resulting in high luminous efficiency. When the amount is 20% by mass or less, poor compatibility does not occur, and the problem of aggregation and sedimentation of the light scattering particles in the composition does not occur, and re-dispersion becomes possible. When it is 5% by mass or more, a sufficient scattering effect is exhibited, resulting in higher luminous efficiency, which is more preferable. If it is 12.5% by mass or less, aggregation of the light scattering particles is suppressed, the haze on the coating film surface does not increase, and high luminous efficiency is obtained, which is more preferable.

The ink composition may contain both inorganic light scattering particles (D1) and organic light scattering particles (D2). In that case, the ratio of the organic light scattering particles (D2) to the inorganic light scattering particles (D1) ((D2)/(D1)) is preferably 0.2 or more and less than 4.5. It is more preferably 0.5 or more and less than 4.0, and particularly preferably 0.5 or more and less than 1.0. By setting the amount within the above range, it is possible to provide an ink composition that suppresses sedimentation of aggregates and is excellent in redispersibility even when sedimentation occurs. Also, a printed matter formed from the ink composition can maintain a high external quantum efficiency.

In the present specification, the terms "average particle size" and "particle size" refer to dispersed particle sizes in the ink composition, which are different from the average primary particle size, taking into consideration the particle size of secondary particles due to aggregation. be. These can be obtained by actual measurement with an optical microscope or by a dynamic light scattering method. Here, the reason for distinguishing from the average primary particle size is that even when scattering particles having the same average primary particle size are used, the average particle size varies depending on the state of dispersion of the light scattering particles (D) in the ink composition. and the particle size distribution may be different. "Average particle size" is the value of the dispersed particle size in 50% by volume of the measurement sample, and the content of particles with a particle size of 600 nm or more is the volume % of the particle size of 600 nm or more among the dispersed particle sizes of the measurement sample. is. These can be measured by the dynamic light scattering method using "Nanotrack UPA" manufactured by Nikkiso Co., Ltd.

<Ink composition>
The ink composition of the present invention is suitably used as an inkjet ink, particularly in an inkjet system.
Other components such as polymerization inhibitors, sensitizers and additives can be added to the ink composition from the viewpoint of required physical properties and storage stability of the printed matter. These can be used alone or in combination of two or more.

(Polymerization inhibitor)
The ink composition may contain a polymerization inhibitor to improve storage stability. Examples of polymerization inhibitors include 4-methoxyphenol, hydroquinone, methylhydroquinone, t-butylhydroquinone, 2,5-t-butyl-4-methylphenol, phenothiazine, aluminum salts of N-nitrosophenylhydroxylamine, and the like. be done. The content of the polymerization inhibitor is preferably 0.01 to 0.1% by mass based on the total solid content of the ink composition, from the viewpoint of enhancing stability while maintaining curability.

(sensitizer)
The ink composition may contain a sensitizer. Sensitizers include chalcone derivatives, unsaturated ketones such as dibenzalacetone, 1,2-diketone derivatives such as benzyl and camphorquinone, benzoin derivatives, fluorene derivatives, naphthoquinone derivatives, and anthraquinone derivatives. , xanthene derivatives, thioxanthene derivatives, xanthone derivatives, thioxanthone derivatives, coumarin derivatives, ketocoumarin derivatives, cyanine derivatives, merocyanine derivatives, polymethine dyes such as oxonol derivatives, acridine derivatives, azine derivatives, thiazine derivatives, oxazine derivatives, indoline derivatives, Azulene derivatives, azulenium derivatives, squarylium derivatives, porphyrin derivatives, tetraphenylporphyrin derivatives, triarylmethane derivatives, tetrabenzoporphyrin derivatives, tetrapyrazinoporphyrazine derivatives, phthalocyanine derivatives, tetraazaporphyrazine derivatives, tetraquinoxalyloporphyrazine derivatives , naphthalocyanine derivatives, subphthalocyanine derivatives, pyrylium derivatives, thiopyrylium derivatives, tetraphylline derivatives, annulene derivatives, spiropyran derivatives, spirooxazine derivatives, thiospiropyran derivatives, metal arene complexes, organic ruthenium complexes, or Michler ketone derivatives, α-acyloxyesters , acylphosphine oxide, methylphenylglyoxylate, benzyl, 9,10-phenanthrenequinone, camphorquinone, ethylanthraquinone, 4,4′-diethylisophthalophenone, 3,3′, or 4,4′ -tetra(t-butylperoxycarbonyl)benzophenone, 4,4'-diethylaminobenzophenone and the like. These sensitizers can be used singly or as a mixture of two or more at any ratio as required.

In addition, the ink composition of the present invention may optionally contain additives such as a surface conditioner, a leveling agent, an ultraviolet absorber, and an antioxidant in order to improve the printability and durability of the printed matter.

The content of the above-mentioned other components depends on the desired quantum dot concentration, but is preferably 0 to 100 parts by mass of the other components with respect to 1 part of the quantum dots. If the amount exceeds 100 parts by mass, the quantum dot content may become low, and sufficient fluorescence intensity may not be obtained.

The ink composition of the present invention has a pore size of 5 μm or less, preferably 3 μm, after dispersion and/or after blending all the components, in order to suppress the generation of foreign matter due to aggregation of particles in the coating film to be formed and to maintain smoothness. It is preferable to filter with the following filters.

When the ink composition of the present invention is used in an inkjet system, the viscosity of the inkjet ink at 25° C. is preferably 2 to 100 mPa·s, more preferably 2 to 40 mPa·s, and particularly preferably 4 to 20 mPa·s. is. Within this viscosity range, it is possible to exhibit stable ejection characteristics from a normal head with a frequency of 4 to 10 KHz to a head with a high frequency of 10 to 50 KHz. When the viscosity is 2 mPa·s or more, it is preferable because no decrease in ejection followability is observed in a high-frequency head. When it is 100 mPa·s or less, it is preferable because the ejection property is good and the ejection stability is excellent.

When the ink composition is used in an inkjet system, the inkjet ink preferably has a surface tension of 20 to 40 mN/m, more preferably 24 to 35 mN/m. When it is 20 mN/m or more, the ink can form droplets, and when it is 40 mN/m or less, the ink can be stably ejected from the head.

The ink composition preferably has an electrical conductivity of 10 μS/cm or less in the piezoelectric head, and is an ink that does not cause electrical corrosion inside the head. In the continuous type, it is necessary to adjust the electric conductivity with an electrolyte, and in this case, it is preferable to adjust the electric conductivity to 0.5 mS/cm or more.

The printed matter of the present invention has a printed layer containing quantum dots formed from an ink composition on a substrate, and the printed layer is preferably formed by an inkjet printing method. When a print is formed by an inkjet method, the ink composition of the present invention is supplied to the printer head of an inkjet recording printer, and the inkjet ink is ejected onto the substrate from the printer head. After that, through a step of drying the solvent contained in the inkjet ink, or a step of irradiating active energy rays such as ultraviolet rays or electron beams to polymerize the polymerizable compound contained in the inkjet ink, on the substrate, An ink layer (printing layer) can be formed.

The step of drying the solvent is not limited as long as the solvent can be removed, and air drying may be used. The drying temperature is preferably 40° C. or higher and 180° C. or lower, and the drying time may be 1 minute or longer, 10 minutes or longer, or 120 minutes or shorter. By setting the temperature within the above range or the drying time, it is possible to obtain a strong coating film in which the solvent is sufficiently dried.

Moreover, when irradiating ultraviolet rays as a light source of active energy rays, for example, a high-pressure mercury lamp, a metal halide lamp, a low-pressure mercury lamp, an extra-high pressure mercury lamp, an ultraviolet laser, an LED, or sunlight can be used. The exposure amount may be 100 mJ/cm ² or more and may be 2000 mJ/cm ² or less. An ink layer having sufficient strength can be obtained by setting the exposure range with the above light source.

The inkjet method is not particularly limited, and known methods such as a charge control method of ejecting ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) using oscillating pressure of a piezoelectric element, an electric signal Acoustic inkjet method that transforms into an acoustic beam and irradiates ink and uses radiation pressure to eject ink, and thermal inkjet method (bubble jet (registered trademark)) that heats ink to form bubbles and uses the pressure generated Any method or the like may be used.

The inkjet head used in the inkjet method may be either an on-demand system or a continuous system. In addition, as the ejection method, electro-mechanical conversion method (e.g. single cavity type, double cavity type, bender type, piston type, share mode type, shared wall type, etc.), electro-thermal conversion method (e.g. thermal inkjet type, bubble jet (registered trademark) type, etc.), electrostatic attraction method (e.g., electrolysis control type, slit jet type, etc.), and discharge method (e.g., spark jet type, etc.). However, any ejection method may be used. Ink nozzles and the like used for recording by the ink jet method are not particularly limited, and can be appropriately selected according to the purpose.

The amount of ink droplets ejected from the inkjet head is preferably from 0.2 to 20 picoliters (pL), more preferably from 1 to 15 picoliters (pL), in view of the large effect of reducing the drying load and the improvement of image quality. is more preferred.

<Base material>
The substrate on which the ink composition of the present invention is printed is not particularly limited, and paper substrates such as woodfree paper, coated paper, art paper, cast paper and synthetic paper; Plastic substrates such as polymethyl methacrylate resin (hereinafter referred to as PMMA), polypropylene, polyethylene and polyethylene terephthalate (hereinafter referred to as PET); metal substrates such as stainless steel; glass; wood; and the like can be used. The inkjet ink of the present invention can be used not only on paper substrates such as special papers and copy papers having an absorbent layer, but also on difficult substrates such as coated papers, art papers and vinyl chloride sheets that are generally used for industrial printing. It can also be suitably used for absorbent substrates.

<Color filter>
The ink composition of the present invention can be used to form a color filter that selectively absorbs incident light by wavelength and transmits or reflects light of a part of wavelengths. In addition, it can also be used for manufacturing color solid-state imaging devices, organic EL display devices, quantum dot display devices, electronic paper, and the like. In particular, when the inkjet method is selected, it is possible to print a required amount at a required location, and it is possible to suppress the consumption of quantum dots and the like, which is preferable.
Also, the color filter comprises a red filter segment, a green filter segment and a blue filter segment, and may further comprise a magenta filter segment, a cyan filter segment and a yellow filter segment, at least one filter segment comprising: It may be formed from the ink composition of the present invention.

When producing a color filter using the ink composition of the present invention, a black matrix may be formed in advance before forming the filter segments on the transparent substrate or the reflective substrate. As the black matrix, a multi-layer film of chromium or chromium/chromium oxide, an inorganic film such as titanium nitride, or a resin film in which a light shielding agent is dispersed is used, but is not limited to these. Alternatively, a thin film transistor (TFT) may be formed in advance on the transparent substrate or the reflective substrate, and then the filter segment may be formed. An overcoat film, a transparent conductive film, or the like may be formed on the color filter of the present invention, if necessary.

<Light wavelength conversion layer>
A layer formed by drying an organic solvent after coating and printing using the ink composition of the present invention or a layer composed of a cured film formed by UV irradiation can be used as the light wavelength conversion layer. The light wavelength conversion layer is capable of converting excitation light into fluorescence on the long wavelength side and emitting it, and is not particularly limited as long as the relationship between the excitation light wavelength and the emission fluorescence wavelength can be maintained. is used as excitation light to obtain green or red fluorescence, and ultraviolet light or visible light is used as excitation light to obtain fluorescence in the near-infrared region.
The thickness of the light wavelength conversion layer is preferably 1 to 500 μm, more preferably 1 to 50 μm, still more preferably 1 to 10 μm. A thickness of 1 μm or more is preferable because a high wavelength conversion effect can be obtained. Moreover, when the thickness is 500 μm or less, the light source unit can be made thinner when incorporated into the light source unit, which is preferable.

<Light wavelength conversion member>
The aforementioned light wavelength conversion layer can be used as a light wavelength conversion member.
The light wavelength conversion member is a member in which the light wavelength conversion layer described above is formed on at least one side of a specific base material. The base material is not particularly limited, but plastic base materials such as polycarbonate, hard vinyl chloride, soft vinyl chloride, polystyrene, styrofoam, PMMA, polypropylene, polyethylene, PET, mixed or modified products thereof, fine paper, art paper, coated paper, Paper substrates such as cast-coated paper, glass, metal substrates such as stainless steel, and the like can be used.
The base material to be used is selected according to the application, but in the case of prepaid cards, transit cards, etc., plastic base materials and mixtures or modified products thereof are preferable from the viewpoint of durability. In the case of one-dimensional barcodes, two-dimensional barcodes, and QR codes (matrix two-dimensional codes) as information recording media, paper substrates are preferable in addition to plastic substrates. A transparent substrate is preferable for a wavelength conversion color filter.

<Light emitting element>
A layer formed using the ink composition of the present invention can be used as a light-emitting layer in a light-emitting element. A light-emitting element has a substrate, a cathode and an anode provided on the substrate, a light-emitting layer between the electrodes, and a charge transport layer on at least one of the cathode and the anode. Furthermore, due to the nature of the light emitting device, at least one of the anode and cathode electrodes is transparent.
As a mode of lamination of the light-emitting element, a mode in which a hole-transporting layer, a light-emitting layer, and an electron-transporting layer are stacked in this order from the anode side is preferable. Furthermore, a charge blocking layer or the like may be provided between the hole-transporting layer and the light-emitting layer or between the light-emitting layer and the electron-transporting layer. A hole injection layer may be provided between the anode and the hole transport layer, and an electron injection layer may be provided between the cathode and the electron transport layer. Further, the light emitting layer may be a single layer, or the light emitting layer may be divided into a first light emitting layer, a second light emitting layer, a third light emitting layer, and the like. Further, each layer may be divided into multiple sublayers.

As the substrate, for example, substrates used in known organic EL elements can be used. The substrate may be a resin film or a gas barrier film, such as JP-A-2004-136466, JP-A-2004-148566, JP-A-2005-246716, JP-A-2005-262529, etc. The gas barrier film described in 1. can also be preferably used.
Although the thickness of the substrate is not particularly specified, it is preferably 30 μm to 700 μm, more preferably 40 μm to 200 μm, still more preferably 50 μm to 150 μm. Furthermore, in any case, the haze is preferably 3% or less, more preferably 2% or less, still more preferably 1% or less, and the total light transmittance is preferably 70% or more, more preferably 80% or more, and still more preferably 90%. That's it.

[anode]
The anode usually has a function as an electrode that supplies holes to an organic compound or inorganic compound layer, and its shape, structure, size, etc. are not particularly limited. Depending on the requirements, it can be appropriately selected from known electrode materials. As mentioned above, the anode is usually provided as a transparent anode. The transparent anode is described in detail in "New Development of Transparent Electrode Films" supervised by Yutaka Sawada, published by CMC (1999). When a plastic base material with low heat resistance is used as the substrate, a transparent anode formed by using ITO, IZO or IGZO at a low temperature of 150° C. or less is preferable.

[cathode]
The cathode generally has a function as an electrode for injecting electrons into an organic compound or inorganic compound layer, and its shape, structure, size, etc. are not particularly limited. Accordingly, it can be appropriately selected from known electrode materials.
Materials constituting the cathode include, for example, metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include group 2 metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, lithium-aluminum alloys, magnesium-silver alloys, and rare earth metals such as indium and ytterbium. These may be used alone, but from the viewpoint of achieving both stability and electron injection properties, two or more of them can be preferably used in combination.

Among these materials, a material mainly composed of aluminum is preferable as the material constituting the cathode. The material mainly composed of aluminum refers to aluminum alone or an alloy of aluminum with 0.01 to 100% by mass of an alkali metal or group II metal (eg, lithium-aluminum alloy, magnesium-aluminum alloy, etc.). The materials for the cathode are described in detail in JP-A-2-15595 and JP-A-5-121172. In addition, a dielectric layer made of a fluoride, oxide, or the like of an alkali metal or group II metal may be inserted between the cathode and the organic compound or inorganic compound layer with a thickness of 0.1 to 5 nm. This dielectric layer can also be viewed as a kind of electron injection layer.

The thickness of the cathode can be appropriately selected depending on the material constituting the cathode, and cannot be defined unconditionally, but is usually about 10 nm to 5 μm, preferably 50 nm to 1 μm. Also, the cathode may be transparent or opaque. The transparent cathode can be formed by forming a thin film of a cathode material with a thickness of 1 to 10 nm and laminating a transparent conductive material such as ITO, IZO or IGZO.

[Light emitting layer]
When an electric field is applied, the light-emitting layer receives holes from the anode, the hole-injection layer, or the hole-transport layer, receives electrons from the cathode, the electron-injection layer, or the electron-transport layer, and forms a recombination field for the holes and electrons. It is a layer having a function of providing light to emit light. The light-emitting layer may be composed only of quantum dots, or may be composed of a mixed layer of quantum dots and a host material. The light-emitting material may further contain a fluorescent light-emitting material or a phosphorescent light-emitting material, and may contain one or more dopants. Preferably, the host material is a charge transport material. The number of host materials may be one or two or more, and examples thereof include a configuration in which an electron-transporting host material and a hole-transporting host material are mixed. Furthermore, the light-emitting layer may contain a material that does not have a charge-transporting property and does not emit light. Further, the light-emitting layer may be one layer or two or more layers, and each layer may emit light of a different color.

Examples of the fluorescent material include benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compound, perinone derivative, oxadiazole derivative, oxazine derivative, aldazine derivative, pyraridine derivative, cyclopentadiene derivative, bisstyrylanthracene derivative, quinacridone derivative, pyrrolopyridine derivative, thiadiazolopyridine derivative, cyclopentadiene derivative, styrylamine derivative, di Various metal complexes such as ketopyrrolopyrrole derivatives, aromatic dimethylidine compounds, metal complexes of 8-quinolinol derivatives and metal complexes of pyrromethene derivatives, polymer compounds such as polythiophene, polyphenylene, and polyphenylene vinylene, compounds such as organic silane derivatives, etc. is mentioned.

Examples of the phosphorescent materials include complexes containing transition metal atoms or lanthanide atoms. The transition metal atom is not particularly limited, but preferably includes ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium and platinum, more preferably rhenium, iridium and platinum.
The lanthanide atoms include lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutecium. Among these lanthanide atoms, neodymium, europium and gadolinium are preferred.

As a ligand for the complex, for example, G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H. Yersin, "Photochemistry and Photophysics of Coordination Compounds," Springer-Verla. ``Organometallic Chemistry - Fundamentals and Applications-'' written by Akio Yamamoto, published by Gsha in 1987. Examples include ligands described in Bosha 1982 publication.

Examples of the host material contained in the light-emitting layer include those having a carbazole skeleton, those having a diarylamine skeleton, those having a pyridine skeleton, those having a pyrazine skeleton, those having a triazine skeleton, and those having an arylsilane skeleton. and materials exemplified in the sections of the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer described below.

[Hole Injection Layer, Hole Transport Layer]
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or from the anode side and transporting them to the cathode side. It may be an organic compound or an inorganic compound, a low-molecular-weight compound, a high-molecular-weight compound, or a metal oxide, as long as it has the functions described above. Specifically, the hole injection layer and the hole transport layer include carbazole derivatives, triphenylamine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylene diamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidine compounds, porphyrin compounds, Phthalocyanine compounds, low molecular weight compounds such as organic silane derivatives, carbon compounds such as carbon and fullerenes, inorganic compounds composed of metal oxides such as vanadium pentoxide and molybdenum trioxide, polyvinylcarbazole, polypyrrole, poly(3,4-ethylene) It is preferably a layer containing a polymer compound such as dioxythiophene)-poly(styrenesulfonic acid) (PEDOT-PSS).

[Electron Injection Layer, Electron Transport Layer]
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side. Specifically, the electron injection layer and the electron transport layer include triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, Carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, aromatic ring tetracarboxylic acid anhydrides such as naphthalene and perylene, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives, metal phthalocyanine, benzoxazole and benzothiazole as ligands Various metal complexes represented by metal complexes, low-molecular-weight compounds such as organic silane derivatives, metal oxides such as zinc oxide (ZnO) and titanium oxide (TiO ₂ ), and organic or inorganic compounds doped with alkali metals. It is preferably a layer that

[Hole blocking layer]
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light-emitting layer from passing through to the cathode side. In the present invention, a hole blocking layer can be provided as an organic compound layer adjacent to the light emitting layer on the cathode side. Further, the electron transport layer/electron injection layer may also function as a hole blocking layer.
Examples of the organic compound forming the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like. Also, a layer having a function of preventing electrons transported from the cathode to the light-emitting layer from passing through to the anode can be provided at a position adjacent to the light-emitting layer on the anode side. The hole transport layer/hole injection layer may also serve this function.

<Light emitting device>
A combination of the light wavelength conversion member and the light emitting element can be used as a light emitting device. In the light emitting device, at least one of the light wavelength conversion layer of the light wavelength conversion member and the light emitting layer of the light emitting element may be formed using the ink composition of the present invention.
The light wavelength conversion member converts the excitation light into fluorescent light on the long wavelength side and emits it. It can be converted to fluorescence in the outer region. The light wavelength conversion member is not particularly limited as long as it maintains the relationship between the wavelength of the excitation light and the wavelength of the emitted fluorescence light, and an optimum one can be selected as appropriate.
As light sources for conventionally known light emitting elements, semiconductor light emitting elements such as light emitting diodes (LED) and semiconductor lasers (LD); organic electroluminescence (organic EL); or quantum dots can be used.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the examples below do not limit the scope of the present invention. In addition, "part" in an Example represents "mass part", and "%" represents "mass %." Also, the mass average molecular weight was measured using GPC and calculated in terms of polystyrene.

<Synthesis of compound (quantum dot treatment agent) represented by general formula (1)>
(Synthesis of Compound 1)
In a Dean-Stark apparatus, 5 parts of thioglycolic acid, 1 part of ethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 1 shown in Table 1. Yield was 70%.

(Synthesis of compound 2)
In a Dean-Stark apparatus, 5 parts of 3-mercaptopropionic acid, 1 part of ethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 2 shown in Table 1. Yield was 72%.

(Synthesis of compound 3)
In a Dean-Stark apparatus, 5 parts of 3-mercaptopropionic acid, 1 part of ethylene glycol monoethyl ether, 0.05 part of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 3 shown in Table 1. Yield was 70%.

(Synthesis of compound 4)
In a Dean-Stark apparatus, 5 parts of thioglycolic acid, 1 part of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 4 shown in Table 1. Yield was 60%.

(Synthesis of compound 5)
In a Dean-Stark apparatus, 5 parts of thioglycolic acid, 1 part of diethylene glycol monoethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 5 shown in Table 1. Yield was 66%.

(Synthesis of compound 6)
In a Dean-Stark apparatus, 5 parts of 3-mercaptopropionic acid, 1 part of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 6 shown in Table 2. Yield was 70%.

(Synthesis of compound 7)
In a Dean-Stark apparatus, 5 parts of 3-mercaptopropionic acid, 1 part of diethylene glycol monoethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 7 shown in Table 2. Yield was 77%.

(Synthesis of compound 8)
5 parts of 3-mercaptopropionic acid, 1 part of diethylene glycol monoisopropyl ether, 0.05 part of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours in a Dean-Stark apparatus. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 8 shown in Table 2. Yield was 73%.

(Synthesis of Compound 9)
In a Dean-Stark apparatus, 5 parts of 3-mercaptopropionic acid, 1 part of diethylene glycol monobutyl ether, 0.05 part of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 9 shown in Table 2. Yield was 70%.

(Synthesis of Compound 10)
In a Dean-Stark apparatus, 5 parts of 4-mercaptobutyric acid, 1 part of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 10 shown in Table 2. Yield was 64%.

(Synthesis of Compound 11)
5 parts of 6-mercaptohexanoic acid, 1 part of diethylene glycol monomethyl ether, 0.05 part of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours in a Dean-Stark apparatus. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 11 shown in Table 3. Yield was 70%.

(Synthesis of compound 12)
In a Dean-Stark apparatus, 5 parts of thioglycolic acid, 1 part of dipropylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 12 shown in Table 3. Yield was 71%.

(Synthesis of compound 13)
In a Dean-Stark apparatus, 5 parts of 3-mercaptopropionic acid, 1 part of dipropylene glycol monoethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 13 shown in Table 3. Yield was 74%.

(Synthesis of compound 14)
In a Dean-Stark apparatus, 5 parts of 2-thiophenecarboxylic acid, 4 parts of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 14 shown in Table 3. Yield was 70%.

(Synthesis of compound 15)
In a Dean-Stark apparatus, 5 parts of 3-thiophenecarboxylic acid, 4 parts of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 15 shown in Table 3. Yield was 72%.

(Synthesis of compound 16)
In a Dean-Stark apparatus, 6 parts of tetrahydrothiopyran-4-carboxylic acid, 5 parts of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 16 shown in Table 4. Yield was 74%.

(Synthesis of compound 17)
In a Dean-Stark apparatus, 4 parts of methylthioacetic acid, 4 parts of diethylene glycol monomethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 17 shown in Table 4. Yield was 68%.

(Synthesis of compound 18)
In a Dean-Stark apparatus, 6 parts of 3-(methylthio)propionic acid, 5 parts of diethylene glycol monoethyl ether, 0.05 parts of concentrated sulfuric acid and 20 parts of toluene were heated under reflux for 3 hours. After adding 40 parts of ethyl acetate, the reaction mixture was washed twice with 20 parts of water and finally with 20 parts of saturated aqueous sodium bicarbonate solution. The organic layer was dried with magnesium sulfate, the magnesium sulfate was filtered off, and the organic solvent was distilled off under reduced pressure to obtain compound 18 shown in Table 4. Yield was 74%.

<Production of quantum dots>
[Comparative Example 1]
(Quantum dot QD-0)
0.55 parts of anhydrous zinc acetate, 7.0 parts of dodecanethiol (compound 0), and 5.0 parts of oleylamine were heated and dissolved to prepare an additive solution. Separately, 0.22 parts of indium chloride and 8.25 parts of octylamine were placed in a reaction vessel and heated to 165° C. while bubbling with nitrogen. After dissolving the indium chloride, 0.86 parts of diethylaminophosphine was briefly injected and the temperature was controlled at 165° C. for 20 minutes. It was then quenched and cooled to 40°C. After pouring the above additive solution and heating at 240° C. for 2 hours, it was allowed to cool to room temperature. After standing to cool, purification was performed by a reprecipitation method using hexane and ethanol. The precipitate was collected and dried under reduced pressure to obtain quantum dots QD-0 in which core-shell semiconductor fine particles having an InP core and a ZnS shell were surface-treated with dodecanethiol (compound 0).

[Example 1]
(Quantum dot QD-1)
Quantum dots QD-0 were dispersed in toluene to a solid concentration of 1%. A 5% toluene solution of Compound 1 in the same amount as the diluted liquid was added and stirred for 12 hours. Purification was performed by a reprecipitation method using toluene and hexane. The precipitate was collected and dried under reduced pressure to obtain quantum dots QD-1 surface-treated with Compound 1.

[Examples 2 to 18, Comparative Examples 2 to 6]
(Quantum dot QD-2 to 23)
Quantum dots QD-2 to 23 were prepared in the same manner as QD-1, except that compound 1 used as a surface treatment agent was changed to compounds 2 to 23 shown in Table 6.

The structures of compounds 0 to 23 are the same as those shown in Tables 1 to 4 above and Table 5 below.

<Production of resin solution>
(Resin solution 1)
A separable 4-necked flask equipped with a thermometer, a cooling tube, a nitrogen gas inlet tube, and a stirring device was charged with 70.0 parts of xylene in a reaction vessel, heated to 80°C, and after replacing the inside of the reaction vessel with nitrogen, a dropping tube was added. A mixture of 18.0 parts of n-butyl methacrylate, 12.0 parts of methyl methacrylate and 0.4 parts of 2,2'-azobisisobutyronitrile was added dropwise over 2 hours. After the dropwise addition, the reaction was continued for 3 hours to obtain an acrylic resin solution having a mass average molecular weight (Mw) of 26,000. After cooling to room temperature, about 2 g of the resin solution was sampled and dried by heating at 180° C. for 20 minutes to measure the solid content concentration. By addition, a resin solution 1 of an acrylic resin was obtained.

(Resin solution 2)
A separable 4-necked flask equipped with a thermometer, a cooling tube, a nitrogen gas inlet tube, and a stirring device was charged with 70.0 parts of xylene in a reaction vessel, heated to 80°C, and after replacing the inside of the reaction vessel with nitrogen, a dropping tube was added. A mixture of 14.0 parts of n-butyl methacrylate, 10.0 parts of methyl methacrylate, 6.0 parts of styrene and 0.4 parts of 2,2'-azobisisobutyronitrile was added dropwise over 2 hours. After the dropwise addition, the reaction was continued for 3 hours to obtain an acrylic resin solution having a mass average molecular weight (Mw) of 26,000. After cooling to room temperature, about 2 g of the resin solution was sampled and dried by heating at 180° C. for 20 minutes to measure the solid content concentration. By addition, a resin solution 2 of an acrylic resin was obtained.

(Resin solution 3)
A butyral resin S-LEC BL-S (manufactured by Sekisui Chemical Co., Ltd.) was dissolved in toluene so that the solid content concentration was 10% to obtain a resin solution 3.

(Resin solution 4)
200 parts of norbornene, 50 parts of cyclopentene, 180 parts of 1-hexene and 750 parts of toluene were placed in a reaction vessel purged with nitrogen and heated to 60°C. To this, 0.62 parts of a toluene solution of triethylaluminum (1.5 mol/l), tert-C4H5OH/CH
Add 3.7 parts of WCl6 solution (concentration 0.05 mol/l) modified with 3OH (tert-C4H9OH/CH3OH/W=0.35/0.3/1; molar ratio) and heat at 80° C. for 3 hours. The mixture was stirred to carry out a ring-opening polymerization reaction and a hydrogenation reaction, and then trimethylbenzene was used to adjust the solid content concentration to 10%.

<Production of light scattering particle (D) dispersion>
(Metal oxide fine particle dispersion (D1-1))
In 60 parts of ethylene glycol monobutyl ether acetate, 20 parts of MT700B (manufactured by Tayca Co., Ltd., fine particle titanium oxide, average primary particle diameter 80 nm) and 20 parts of BYK-2155 (manufactured by Big Chemie Co., Ltd.) were blended, and glass beads ( Particle size: 850 to 1180 μm) was added, and dispersion treatment was performed using a paint conditioner for 2 hours to obtain a metal oxide fine particle dispersion liquid (D1-1).
The average particle size of the metal oxide fine particles in the obtained metal oxide fine particle dispersion (D1-1) was 85 nm.

(Metal oxide fine particle dispersion (D1-2))
A metal oxide fine particle dispersion (D1 -2) was obtained.
The average particle size of the metal oxide fine particles in the resulting metal oxide fine particle dispersion (D1-2) was 48 nm.

(Metal oxide fine particle dispersion (D1-3))
A metal oxide was prepared in the same manner as the metal oxide fine particle dispersion (D1-1) except that MT700B was changed to MT600SA (manufactured by Tayca Co., Ltd., Si, Al treatment, fine particle titanium oxide, average primary particle size 50 nm). A fine particle dispersion (D1-3) was obtained.
The average particle size of the metal oxide fine particles in the resulting metal oxide fine particle dispersion (D1-3) was 49 nm.

(Organic fine particle dispersion (D2-1))
In a nitrogen atmosphere, 50 parts of trifluoroethyl methacrylate, 40 parts of methyl methacrylate, 5 parts of allyl methacrylate, and 5 parts of isobornyl methacrylate are added to 560 parts of water, stirred, and heated to 80°C. An aqueous solution prepared by dissolving 0.167 parts of ,2-azobis(2-amidinopropane) dihydrochloride in a very small amount of water was added all at once, and polymerization was carried out at 80° C. for 8 hours. After the polymerization, ethylene glycol monobutyl ether was added, and water was removed by stripping to adjust the solid content to 20% by mass, thereby obtaining an organic fine particle dispersion (D2-1) which is fluorine atom-containing acrylic resin fine particles.
The average particle size of the organic fine particles in the resulting organic fine particle dispersion (D2-1) was 280 nm.

(Organic fine particle dispersion (D2-2 to 4))
Organic fine particles that are fluorine atom-containing acrylic resin fine particles were prepared in the same manner as the organic fine particle dispersion liquid (D2-1), except that the solvent composition and monomer composition were changed to the compositions and blending amounts (parts) shown in Table 7. Dispersions (D2-2 to 4) were obtained. Table 7 shows the average particle size of the obtained organic fine particle dispersion.

(Organic fine particle dispersion (D2-5))
In 80 parts of ethylene glycol monobutyl ether acetate, 16.0 parts of Eposter S (manufactured by Nippon Shokubai Co., Ltd., melamine / formaldehyde condensate, average particle size 200 nm), BYK-111 (manufactured by Big Chemie Co., Ltd.) 4.0 parts Glass beads (particle size: 850-1180 μm) were added, and dispersion treatment was performed using a paint conditioner for 2 hours to obtain an organic fine particle dispersion (D2-5), which is melamine resin fine particles.
The average particle size of the organic fine particles in the resulting organic fine particle dispersion (D2-5) was 175 nm.

(Organic fine particle dispersion (D2-6))
Eposter S was changed to Eposter FS (manufactured by Nippon Shokubai Co., Ltd., melamine-formaldehyde condensate, average particle size: 200 nm). A fine particle dispersion (D2-6) was obtained.
The average particle size of the organic fine particles in the resulting organic fine particle dispersion (D2-6) was 173 nm.

(Organic fine particle dispersion (D2-7))
Crosslinked acrylic resin fine particles in the same manner as the organic fine particle dispersion (D2-5) except that Eposter S was changed to MX-80HwTM (manufactured by Soken Chemical Co., Ltd., crosslinked acrylic monodisperse particles, average particle diameter 800 nm). A certain organic fine particle dispersion liquid (D2-7) was obtained.
The average particle size of the organic fine particles in the resulting organic fine particle dispersion (D2-7) was 732 nm.

(Organic fine particle dispersion (D2-8))
Except for changing Eposter S to MX-80HwTM (manufactured by Soken Chemical Co., Ltd., crosslinked acrylic monodisperse particles, average particle size 800 nm) and BYK-111 to BYK-2155 (manufactured by Big Chemie Co., Ltd.), the organic fine particle dispersion ( An organic fine particle dispersion (D2-8), which is a crosslinked acrylic resin fine particle, was obtained in the same manner as in D2-5).
The average particle size of the organic fine particles in the resulting organic fine particle dispersion (D2-8) was 673 nm.

<Preparation of ink composition>
[Example 101]
(Ink composition 1)
20 parts of quantum dots (QD-1) and 150 parts of resin solution were weighed into a sealable container, and 30 parts of diethylene glycol monobutyl ether acetate was added. After that, the mixture was sealed and stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain an ink composition 1.

[Examples 102 to 121, Comparative Examples 101 to 106]
(Ink compositions 2 to 21, 57 to 62)
Ink compositions 2 to 21 and 57 to 62 were prepared in the same manner as ink composition 1, except that the quantum dots, the resin solution, and the solvent were weighed in the order shown in Table 8 in a sealed container. bottom. In Comparative Examples 101 to 106, an amount of solvent was added to completely disperse 20 parts of the quantum dots.

[Example 122]
(Ink composition 22)
50 parts of resin solution 1, 20 parts of quantum dots (QD-1), 16 parts of metal oxide fine particle dispersion (D1-1), and 14 parts of diethylene glycol monobutyl ether acetate were weighed into a sealable container. After that, the mixture was tightly sealed, stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain an ink composition 22 .

[Examples 123 to 140]
(Ink compositions 23 to 40)
Ink compositions 23 to 23 were prepared in the same manner as ink composition 22 except that the resin solution, the quantum dots, the metal oxide fine particle dispersion, and the solvent were weighed in the order shown in Table 8 in a sealable container. 40 was prepared.

[Example 141]
(Ink composition 41)
In a container that can be closed, 52 parts of diethylacrylamide, 20 parts of quantum dots (QD-6), Omnirad 907 (IGM Resins B.V. photopolymerization initiator) 6 parts, Kayacure DETX-S (manufactured by Nippon Kayaku Co., Ltd. Photopolymerization initiator) 2 parts were weighed. After that, the mixture was tightly sealed, stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain an ink composition 41 .

[Examples 142 and 143]
(Ink compositions 42, 43)
Ink compositions 42 and 43 were prepared in the same manner as ink composition 41, except that the polymerizable compound, quantum dots, Omnirad 907, and Kayacure DETX-S were weighed in the order shown in Table 8 in a sealable container. was prepared.

[Example 144]
(Ink composition 44)
32 parts of diethylacrylamide, 20 parts of quantum dots (QD-6), 6 parts of Omnirad 907, 2 parts of Kayacure DETX-S, and 20 parts of metal oxide fine particle dispersion (D1-1) were weighed in a sealable container. After that, the mixture was tightly sealed, stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain an ink composition 44 .

[Examples 145-153, Comparative Examples 107-110]
(Ink Compositions 45-53, 63-66)
In a container that can be sealed, with the formulation shown in Table 8, the polymerizable compound, quantum dots, Omnirad 907, Kayacure DETX-S, metal oxide fine particle dispersion, and organic fine particle dispersion were weighed in that order. Ink Compositions 45-53, 63-66 were prepared in the same manner as Product 44.

[Example 154]
(Ink Composition 54)
In a container that can be sealed, 20 parts of quantum dots (QD-6), 4 parts of jER1001 (manufactured by Mitsubishi Chemical Corporation, epoxy resin), Laccamide TD-984 (manufactured by DIC Corporation, solvent-free polyamidoamine type amine curing agent) 0.8 parts, 42.4 parts of toluene, and 12.8 parts of metal oxide fine particle dispersion (D1-1) were weighed. Thereafter, the mixture was tightly sealed, stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain an ink composition 54 .

[Example 155, Comparative Example 111]
(Ink compositions 55, 67)
Quantum dots, a resin, a curing agent, a solvent, and a dispersion of metal oxide fine particles were weighed into a sealable container according to the composition shown in Table 8. Then, the mixture was sealed and stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain ink compositions 55 and 67.

[Example 156]
(Ink Composition 56)
20 parts of quantum dots (QD-6) and 60 parts of diethylene glycol monobutyl ether acetate were added to a sealable container. After that, the mixture was tightly sealed, stirred, and filtered using a membrane filter with a pore size of 1 μm to obtain an ink composition 56 .

Abbreviations in Table 8 are shown below.
DBCA: diethylene glycol monobutyl ether acetate (boiling point 247°C, SP value 8.9, corresponding to solvent (S-1))
PGMAc: propylene glycol methyl ether acetate (boiling point 147°C, SP value 8.7, corresponding to solvent (S-2))
MEK: methyl methyl ketone DEAA: diethylacrylamide DPGDA: dipropylene glycol diacrylate jER1001: epoxy resin manufactured by Mitsubishi Chemical Corporation, epoxy equivalent weight 450-500, number average molecular weight 900
Vylon 200: polyester resin manufactured by Toyobo Co., Ltd., glass transition temperature 67°C, number average molecular weight 17,000
TD-984: Solvent-free polyamidoamine type amine curing agent "Laccamide TD-984" manufactured by DIC, amine value 285 to 315 mgKOH/g
D110N: "Takenate D-110N" manufactured by Mitsui Chemicals, Inc., trimethylolpropane-modified xylylene diisocyanate Initiator 1: Photopolymerization initiator "Omnirad 907" manufactured by IGM Resins B.V., α-aminoalkylphenone initiator 2 : Nippon Kayaku photopolymerization initiator "Kayacure DETX-S", 2,4-diethylthioxanthone

<Evaluation of Ink Composition>
The obtained ink composition was evaluated as follows. Table 9 shows the results.

[Excitation light transmittance]
The resulting ink composition was applied to a transparent film (polyester film Lumirror 75S10 manufactured by Toray Industries, Inc.) using a bar coater so that the film thickness after drying was 6.0 μm, and dried in an environment of 100°C. rice field. The excitation light transmittance of the obtained coating film was measured using QE-2000 manufactured by Otsuka Electronics Co., Ltd. and evaluated according to the following criteria. Incidentally, the excitation wavelength was set to 450 nm.
◎: less than 10% (good)
○: 10% or more and less than 20% (usable)
△: 20% or more and less than 30% (cannot be used)
×: 30% or more (defective)

[External quantum efficiency]
The resulting ink composition was applied to a transparent film (polyester film Lumirror 75S10 manufactured by Toray Industries, Inc.) using a bar coater so that the film thickness after drying was 6.0 μm, and dried in an environment of 100°C. rice field. The ink composition containing a polymerizable compound was applied to a transparent film (polyester film Lumirror 75S10 manufactured by Toray Industries, Inc.) using a bar coater so that the film thickness after drying was 6.0 μm, and the coated film was dried with nitrogen. Using an LED irradiator installed in the replaced glove box, an integrated light amount of 500 mJ/cm ² (in terms of UVA) was applied to cure the film. The ink composition containing the curing agent was cured by aging at 40° C. for 3 days instead of drying after coating. The external quantum efficiency (EQE) of the resulting coating film was measured using QE-2000 manufactured by Otsuka Electronics Co., Ltd. and evaluated according to the following criteria. The excitation wavelength was set to 450 nm, and the fluorescence wavelength integration range was set to 500 nm to 800 nm.
◎: 20% or more (very good)
○: 15% or more and less than 20% (good)
△: 10% or more and less than 15% (usable)
×: less than 10% (cannot be used)

[Dispersion stability]
The obtained ink composition was measured immediately after the preparation of the ink composition and after 48 hours at 25°C (after 12 hours at 0°C for the ink composition containing a curing agent) using a vibrating viscometer Viscomate VM-10A-. L (manufactured by SEKONIC) was used to measure the viscosity at 25° C., calculate the rate of change in viscosity, and evaluate according to the following criteria.
◎: Viscosity change rate is less than ±2.5% (very good)
○: Viscosity change rate is ±2.5% or more and less than ±5% (usable)
△: Viscosity change rate is ±5% or more and less than ±10% (cannot be used)
×: Viscosity change rate is ±10% or more (defective)

[IJ printing test]
Using the obtained ink composition, an IJ printing test was performed under the following conditions. The resulting printed matter and ejection conditions were evaluated according to the following criteria.
Instead of drying after printing, the ink composition containing a polymerizable compound was cured by irradiating an integrated light amount of 500 mJ/cm ² (in terms of UVA) using an LED irradiator installed in a nitrogen-substituted glove box. . The ink composition containing the curing agent was cured by aging at 40° C. for 3 days instead of drying after printing.
(Printing conditions)
PrinterDimatixMaterialsPrinter
Cartridge 10 Dimatix Materials Cartridges, 10 pL
Grid pattern substrate with printed pattern 1 mm interval Round cover glass Matsunami glass industry substrate temperature 30 ° C
Dry after printing at 40°C for 20 minutes (evaluation criteria)
○: Discharge was possible according to the printing pattern (good)
×: Nozzle clogging occurred (defective)

[IJ continuous ejection]
Using the obtained ink composition, IJ continuous ejection was performed in the same manner as in the printing test described above. The discharge state was visually confirmed and evaluated according to the following criteria.
(Evaluation criteria)
◯: Continuous ejection possible time is 30 minutes or more (good)
Δ: Continuous ejection possible time is 10 minutes or more and less than 30 minutes (usable)
×: Continuous ejection possible time is less than 10 minutes (cannot be used)

The coating film containing the quantum dots of the present invention, which are semiconductor fine particles surface-treated with a specific ligand compound, has a low excitation light transmittance, a high external quantum efficiency (EQE), and excellent dispersion stability. rice field. In addition, it was shown that the ink composition containing the quantum dots of the present invention has good IJ ejection properties and is useful for inkjet inks.
All of Examples 101 to 166 were excellent in excitation light transmittance. This is because the compounds 1 to 18 used in Examples 101 to 166 are compounds having an alkyleneoxy chain and having a molecular weight within a predetermined range, thereby increasing the affinity between the solvent and the quantum dots and increasing the excitation light transmittance. This is thought to be because the quantum dots were dispersed to a concentration at which the was the qualifying level.
Among Examples 101 to 166, in Examples 122 to 129 and 132 to 155 in which a light scattering particle dispersion was used in combination, the excitation light transmittance was further improved, and the light scattering particles functioned as scatterers to disperse the excitation light. permeation was suppressed. The external quantum efficiency is also improved with the combined use of the light scattering particles, which is considered to be the result of an increase in the number of paths through which the scattered light is absorbed by the quantum dots. In Examples 125, 127, and 128, the dispersion stability is at a particularly high level, and the corresponding compound (surface treatment agent) has the ability to stably disperse quantum dots even in the presence of a light scattering particle dispersion. presumed to be

Claims (11)

Quantum dots (A), which are semiconductor fine particles surface-treated with a compound represented by the following general formula (1) and having a molecular weight of 250 or less.
General formula (1): QR ¹ -X-(R ² -O) _n -R ³
[In the general formula (1), Q is a sulfanyl group, an alkylsulfanyl group, or a monovalent heterocyclic group containing a sulfur atom, R ¹ is a direct bond or an alkylene group having 1 to 6 carbon atoms, and X is an ester bond, ^R2 is an ethylene or propylene group, ^R3 is an alkyl group, and n is an integer of 1 or 2. ] Quantum dots (A) according to claim 1, wherein the semiconductor fine particles are compound semiconductors. 3. The quantum dot (A) according to claim 1 or 2, wherein the semiconductor fine particles are core-shell type, and the shell surface is treated with the compound represented by the general formula (1). The quantum dot (A) according to any one of claims 1 to 3, wherein Q in the general formula (1) is a sulfanyl group. The quantum dot (A) according to any one of claims 1 to 4, wherein R ¹ in general formula (1) is an alkylene group having 1 to 6 carbon atoms. The quantum dot (A) according to any one of claims 1 to 5, wherein the compound represented by the general formula (1) has a molecular weight of 180 to 230. An ink composition comprising the quantum dots (A) according to any one of claims 1 to 6 and a solvent (B). An ink composition comprising the quantum dots (A) according to any one of claims 1 to 6 and a binder component (C). 9. The ink composition according to claim 7, further comprising light scattering particles (D). The ink composition according to any one of claims 7 to 9, which is used in an inkjet system. A printed matter formed using the ink composition according to any one of claims 7 to 10.