JP2021103212A - Ink composition, laminate formed by using ink composition, optical wavelength conversion layer, optical wavelength conversion member and color filter - Google Patents

Abstract

To provide an ink composition which can perform printing without impairing the fluorescent characteristics of quantum dots, especially perform printing in an ink jet method and has the low viscosity, a laminate which is formed from the composition and is excellent in the wavelength conversion efficiency, an optical wavelength conversion layer, an optical wavelength conversion member and a color filter.SOLUTION: The above-mentioned problem is solved by an ink composition comprising: (A) quantum dot; (B) a polymerizable compound including α-allyloxymethyl acrylic acid alkyl; and (C) a photoinitiator, a laminate which is formed from the composition and excellent in the wavelength conversion efficiency, an optical wavelength conversion layer, an optical wavelength conversion member and a color filter.SELECTED DRAWING: None

Description

INDUSTRIAL APPLICABILITY The present invention has an ink composition containing quantum dots, which has excellent ink stability and curability and exhibits higher light efficiency characteristics, a laminate made by using the composition, an optical wavelength conversion layer, and light. The present invention relates to a wavelength conversion member and a color filter.

Quantum dots are tiny particles (dots) formed to confine electrons in a minute space in order to express unique optical properties that follow quantum mechanics. The size of one quantum dot is from 1 nanometer to several tens of nanometers in diameter, and is composed of about 10,000 or less atoms, and the wavelength of fluorescence emitted is continuously controlled by the size of the grain. It has been attracting attention in recent years because it can produce sharp light emission with highly symmetric wavelength distribution of fluorescence intensity.

Quantum dots can adjust fluorescence to a wavelength that easily penetrates the human body and can be delivered to anywhere in the body, so they are used for bioimaging as a light emitting material, as a wavelength conversion material that does not fade, for solar cells, clear light emitting materials, and wavelengths. Development studies are underway for applications such as electronics and photonics as conversion materials.
When developing for these applications, it is necessary to form a fine pattern. Therefore, a method has been proposed in which a resist solution is prepared using a photosensitive material for pattern formation and light is irradiated through a mask (Patent Document 1). On the other hand, a quantum dot-containing inkjet ink using an inkjet method has been proposed as a pattern forming method that does not require resisting. (Patent Documents 2 and 3)

Japanese Unexamined Patent Publication No. 2015-127733 JP-A-2018-109141 International Publication No. 2018/123103

However, the invention of Patent Document 1 has problems such as deterioration of quantum dots during light irradiation and deterioration of utilization efficiency of quantum dot materials due to outflow of quantum dots during development. Further, in the inkjet method, it is very difficult to balance the ink characteristics, particularly the ejection property and the adhesion after printing, and the performance balance such as the light efficiency characteristics of the quantum dots. Not obtained. In particular, in order to adapt to the current inkjet method, it is necessary to reduce the viscosity to about 8 to 15 mPa · s.
Therefore, an object of the present invention is a low-viscosity ink composition that can be printed without impairing the fluorescence characteristics of quantum dots, and is particularly printable by an inkjet method, and a laminate formed from the composition and having excellent wavelength conversion efficiency. , An optical wavelength conversion layer, an optical wavelength conversion member, and a color filter.

As a result of diligent studies to solve the above problems, it was found that the above problems can be solved by the following embodiments, and the present invention has been completed.

An embodiment of the present invention relates to an ink composition containing a quantum dot (A), a photopolymerizable compound (B) containing an alkyl α-allyloxymethylacrylate, and a photopolymerization initiator (C).

Another embodiment of the present invention relates to the ink composition in which the content of the quantum dots (A) is 10% by mass or more and 50% by mass or less based on the total solid content in the composition.

Another embodiment of the present invention relates to the above-mentioned ink composition in which the content of the alkyl α-allyloxymethylacrylate is 5% by mass or more and 40% by mass or less based on the total solid content in the composition.

In another embodiment of the present invention, the content of the alkyl α-allyloxymethylacrylate is 10% by mass or more and 35% by mass or less based on the total amount of the photopolymerizable compound (B). Regarding.

Another embodiment of the present invention relates to the above ink composition, wherein the photopolymerizable compound (B) further contains a photopolymerizable compound having an amide group.

Another embodiment of the present invention relates to the above ink composition further containing light scattering particles (D).

Another embodiment of the present invention relates to the ink composition in which the light scattering particles (D) are particles made of a metal oxide.

Another embodiment of the present invention relates to the ink composition having a viscosity at 25 ° C. in the range of 5 to 30 mPa · s.

Another embodiment of the present invention relates to the above-mentioned ink composition for active energy ray-curable inkjet ink.

Another embodiment of the present invention relates to a laminate having a plurality of layers, wherein at least one layer has a light emitting layer made of the ink composition.

Another embodiment of the present invention relates to a light wavelength conversion layer made of the above ink composition.

Another embodiment of the present invention relates to an optical wavelength conversion member having the above optical wavelength conversion layer.

Another embodiment of the present invention relates to a color filter including a filter segment formed by using the above ink composition on a base material.

INDUSTRIAL APPLICABILITY According to the present invention, a low-viscosity ink composition that can be printed without impairing the fluorescence characteristics of quantum dots and that can be printed by an inkjet method, a laminate formed from the composition and having excellent wavelength conversion efficiency, and a light wavelength. A conversion layer, an optical wavelength conversion member, and a color filter can be provided.

<Ink composition>
The ink composition of the present invention is characterized by containing a quantum dot (A), a photopolymerizable compound (B) containing an alkyl α-allyloxymethylacrylate, and a photopolymerization initiator (C). By combining the alkyl α-allyloxymethylacrylate and the quantum dots, the viscosity of the obtained ink composition can be kept low without impairing the fluorescence characteristics of the quantum dots.
Hereinafter, the present invention will be described in detail.

[Quantum dot (A)]
The quantum dots used in the present invention are not particularly limited, and any nano-sized semiconductor that can emit light by photoexcitation can be used. Among them, a compound semiconductor containing at least one element selected from the group consisting of Group 2 elements, Group 10 elements, Group 11 elements, Group 12 elements, Group 13 elements, Group 14 elements, Group 15 elements and Group 16 elements is preferable. Used for. The compound semiconductor may contain two or more kinds of elements.

Examples of the quantum dot (A) include Si, Ge, Sn, Se, Te, B, C (including diamond), P, Co, Au, BN, BP, BAs, AlN, AlP, AlAs, AlSb, and GaN. , GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe , HgTe, BeS, BeSe, BeTe , MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si 3 N 4, Ge 3 N 4 , Al ₂ O ₃ , (Al, Ga, In) ₂ (S, Se, Te) ₃ , Al ₂ CO ₃ , AgInSe ₂ , CuGaSe ₂ , CuInS ₂ , CuGaS ₂ , CuInSe ₂ , AgGaSe ₂ , AgGaS ₂ , CsPb _{Appropriate combinations of 3} , CsPbI ₃ , CsPbBr ₃ and two or more materials are mentioned.
Of the above, at least two kinds selected from the element group represented by Zn, Cd, B, Al, Ga, In, C, Si, Ge, Sn, N, P, As, Sb, Pb, S, Se and Te. A semiconductor composed of a compound containing the above elements is preferable, and more preferably, at least 2 selected from the element group represented by Zn, B, Al, Ga, In, C, Si, Ge, Sn, N, P, S and Te. It is a semiconductor composed of a compound containing a seed element, more preferably a semiconductor containing In as a constituent element due to the narrow band gap, and is preferably used in applications that emit visible light.

The structure of the quantum dot (A) is a uniform single structure, a multi-layer structure such as a core / shell type structure, a gradient structure, or a mixed structure thereof, as long as it is a structure containing the above-mentioned elements. May be good.

The quantum dot (A) is preferably a compound semiconductor having a core / shell type structure. The shell structure may be one layer or two layers, and if the core structure is covered with a compound semiconductor component different from the compound semiconductor component forming the core and the outside is a compound semiconductor having a large bunt gap, energy excitation such as light is performed. The excitons (electron-hole pairs) generated by are confined in the core. As a result, the probability of non-radiation transition on the surface of the compound semiconductor is reduced, and the quantum yield of light emission and the stability of the fluorescence characteristics of the quantum dots are improved.
Suitable material combinations that satisfy the above conditions when used as quantum dots include, for example, CdSe / ZnS, CdSe / ZnSe, CdS / ZnS, CdSe / CdS, CdTe / CdS, InP / ZnS, InP / ZnSeZnS, PbSe / PbS, GaP / ZnS, Si / ZnS, InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, InGaP / ZnSS Can be mentioned.

ZnS, CdS, ZnSe and the like are preferably used as the shell component of the compound semiconductor forming the quantum dots (A). Among them, when the core component contains In and P as constituent elements, ZnS is particularly excellent in characteristics such as exciton confinement as a quantum dot, and is preferably used.

Further, as a material of the semiconductor fine particles, a perovskite crystal can also be preferably used. The perovskite crystal suitable as the quantum dot of the present invention has a composition represented by the following general formula (1) and has a three-dimensional crystal structure.
General formula (1): ABX ₃
In the general formula (1), A is a monovalent cation of at least one amine compound selected from _{methylammonium (CH 3} NH ₂ ) and formamidinium (NH _{2 CHNH), or rubidium.} It is a monovalent cation of at least one alkali metal element selected from (Rb), cesium (Ce), and francium (Fr), and B is at least one selected from lead (Pb) and tin (Sn). It is a divalent cation of a metal element, where X is a monovalent anion of at least one halogen element selected from iodine (I), bromine (Br), and chlorine (Cl). A feature of perovskite crystals is that they can cover almost all wavelengths in the visible light region from red to blue with a narrow half-value width depending on the ratio of halogen elements in the crystal.

The average particle size of the inorganic material portion of the compound semiconductor is preferably 0.5 nm to 100 nm, and can be appropriately selected depending on the desired properties. The average particle size of the semiconductor fine particles and the core / shell type core average particle size in the case of a single semiconductor composition are preferably 0.5 nm to 25 nm, and more preferably 0.5 nm to 15 nm. When the average particle size is 0.5 nm or more, it is preferable in terms of synthesis, and when it is 100 nm or less, the quantum confinement effect is improved and the desired fluorescence can be obtained.

The quantum dot (A) is characterized in that the fluorescence wavelength can be arbitrarily changed by changing the core particle size even if the material is the same, and it is necessary to set the particle size according to the desired fluorescence wavelength. .. In the case of the core / shell type, a plurality of shell fine particles may be contained in one compound semiconductor, and the average thickness of the shell corresponds to the difference between the particle radius of the inorganic material portion and the core particle radius.

Here, the average particle size refers to a value obtained by observing compound semiconductor fine particles with a transmission electron microscope, randomly measuring 30 sizes, and adopting the average value. At this time, the semiconductor fine particles can be accompanied by an organic ligand described later. On the other hand, by using a scanning transmission electron microscope accompanied by energy dispersive X-ray analysis, semiconductor fine particles excluding organic ligands are specified and the particle size is measured. The identification of the semiconductor fine particles utilizes the fact that the semiconductor fine particles are imaged darker than the organic ligand in the transmission electron microscope image due to the difference in electron density. The shape of the semiconductor fine particles is not limited to a spherical shape, and may be a rod shape, a disk shape, or any other shape.

The quantum dots (A) may be further surface-treated with a ligand compound. "Surface-treated" means having a ligand on at least a part of the surface of the compound semiconductor fine particles, and the ligand present on the surface of such semiconductor fine particles is a coating material, a protective material, a treatment agent, or a treatment agent. Also called a ligand.
A compound generally used as a ligand has a strong polarity or unshared electron pair adsorbed on a metal portion of semiconductor fine particles, and further has a carbon chain having a high affinity with a solvent or resin used for coating liquid or ink. It has a partial structure in which aromatic rings are linked or a partial structure derived from polyalkylene glycol. As such a ligand, an organic pigment, a dispersant of an inorganic pigment or an inorganic compound material, a detergent or a surfactant used at the time of forming an emulsion, or a commonly known emulsifier can be used. Further, as a compound having a partial structure used as a ligand of a metal complex, in particular, a compound having a chelate ligand structure having two or more coordination bonds to a metal is easily adsorbed on the metal portion of the semiconductor fine particles. Since it is difficult to desorb, it can be used as a ligand.

In particular, the ligand that can be used during synthesis preferably has a boiling point of 200 ° C. or higher from the viewpoint of increasing the reaction efficiency because the synthesis temperature is relatively high, and an alkyl having 8 or more carbon atoms from the viewpoint of dispersion stability. Those having a group as a partial structure are preferable. Further, the ligand may have a polar group in order to strengthen the action on the compound semiconductor, and examples of such a ligand include organic acids, organic amines, sulfur-containing organic substances, phosphorus-containing organic substances and the like.

Examples of the organic acid include compounds having a carboxyl group, and the organic acid may have a plurality of carboxyl groups in the molecule. Specific examples of organic acids include benzoic acid, biphenylcarboxylic acid, butylbenzoic acid, hexylbenzoic acid, cyclohexylbenzoic acid, naphthalenecarboxylic acid, hexanoic acid, heptanic acid, octanoic acid, ethylhexanoic acid, hexenoic acid, and octene. Acids, citronellic acid, siberic acid, ethylene glycol bis (4-carboxyphenyl) ether, (2-butoxyethoxy) acetic acid can be mentioned.
Examples of organic acids having an alkyl group having 8 or more carbon atoms as a partial structure include nonanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, tricosanoic acid, lignoceric acid, oleic acid, eikosazienoic acid, and linolene. Acids, sebacic acid and (2-octyloxy) acetic acid can be mentioned.

As the organic amine, a compound having an amino group can be used, and examples thereof include n-butylamine, iso-butylamine, tert-butylamine, n-hexylamine, n-heptylamine, and cyclohexylamine.
Examples of the organic amine having an alkyl group having 8 or more carbon atoms as a partial structure include octylamine, dodecaamine, heptadecane-9-amine, N, N-dimethyl-n-octylamine and the like.

Examples of sulfur-containing organic substances include thiols and disulfides.
Examples of thiols include allyl mercaptan, 1,3-benzenedimethanethiol, 2-amino-5-mercapto-1,3,4-thiasiazol, 3-amino-5-mercapto-1,2,4-triazole. Butanethiol, n-hexanethiol and n-heptanethiol can be mentioned.
Examples of thiols having an alkyl group having 8 or more carbon atoms as a partial structure include dodecane thiol, 1-docosan thiol, tert-dodecyl mercaptan, and 2-ethylhexane thiol.
Examples of disulfides include bis (4-chloro-2-nitrophenyl) disulfide, hexyl sulfide, 3,3', 5,5'-tetrachlorodiphenyl disulfide.
Examples of sulfides having an alkyl group having 8 or more carbon atoms as a partial structure include dodecyl disulfide, octadecyl disulfide, and dodecyl octadecyl disulfide.

Examples of phosphorus-containing organic substances include butyl phosphate, hexyl phosphate, diisopropyl phosphate, mono-2-ethylhexyl (2-ethylhexyl) phosphonate, propylphosphonic acid, hexylphosphonic acid, methyl hexylphosphonate, and hexyl isopropylphosphonate. Can be mentioned.
Examples of phosphorus-containing organic substances having an alkyl group having 8 or more carbon atoms as a partial structure include octyl phosphate, didodecyl phosphate, dodecyl phosphate, dodecylphosphonic acid, dodecyl hexylphosphonate, decylphosphonic acid, and isopropyl decylphosphonate. Can be mentioned.

As a method for producing the quantum dots (A), known production methods such as a method for synthesizing in glass, a method for synthesizing in an aqueous solution, and a method for synthesizing in an organic solvent can be used.

Further, at least a part of the surface of the compound semiconductor may be coated with a ligand different from that at the time of synthesis. Examples of the method of changing the ligand include a method of stirring the compound semiconductor surface-treated with the first ligand and the second coating material to be replaced in a diluting solvent, or a method of surface-treating with the first ligand. Examples thereof include a method of redispersing the compound semiconductor in a solvent containing a second coating material to be replaced after the solvent is roughly removed by centrifugation or the like.
By using the above method, a ligand suitable for the application and required characteristics can be selected, and the affinity with a solvent or resin preferably used for a coating liquid or an ink can be improved.

The content of the quantum dots (A) is preferably 5 to 50% by mass, more preferably 10 to 50% by mass, based on the total solid content in the ink composition. When the content is 5% by mass or more, it is preferable because the light escape of the excitation light (backlight) can be suppressed and the wavelength is sufficiently converted. When the content is 50% by mass or less, the dispersion stability of the ink composition is good, and the viscosity is within the range of the viscosity that can be ejected as an inkjet ink, which is preferable.

[Photopolymerizable compound (B)]
The photopolymerizable compound (B) in the present invention contains alkyl α-allyloxymethylacrylate as an essential component, and alkyl α-allyloxymethylacrylate is a compound represented by the following general formula (1).

General formula (1)

[In the general formula (1), R ₁ represents an alkyl group. ]

_{R 1} of the general formula (1) is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group. Methyl α-allyloxymethyl acrylate having R ₁ as a methyl group not only has a low viscosity by itself, but also has excellent compatibility and solubility. Normally, the viscosity of the mixed liquid is almost the same as the calculated value obtained by multiplying the viscosity of each component alone by the mixing ratio, but the ink containing α-allyloxymethylacrylate as a polymerizable compound. The composition is preferable because the viscosity is significantly lower than the above calculated value and the viscosity reducing effect is excellent.

Further, when the alkyl α-allyloxymethylacrylate is blended with the quantum dots (A) or the light scattering particles (D) described later, they rarely decrease the dispersibility or increase the viscosity. It can be used in a wide range of compounding ratios. Therefore, the excitation light transmission can be suppressed while sufficiently maintaining the printability and the curability, and the external quantum efficiency can be easily increased.
The content of the alkyl α-allyloxymethylacrylate is preferably 5 to 50% by mass, more preferably 10 to 35% by mass, based on the total amount of the photopolymerizable compound (B). When it is 5% by mass or more, the viscosity lowering effect is sufficiently exhibited, which is preferable. When it is 50% by mass or less, it is preferable because the curability of the ink composition is excellent.

The content of alkyl α-allyloxymethylacrylate is preferably in the range of 5 to 40% by mass, more preferably 10 to 25% by mass, based on the total solid content of the ink composition. When it is 5% by mass or more, the viscosity lowering effect is sufficiently exhibited, which is preferable. When it is 40% by mass or less, the relative amount of the quantum dots (A) is sufficient and the light efficiency characteristics are excellent, which is preferable.

The photopolymerizable compound (B) contains alkyl α-allyloxymethylacrylate as an essential component, and may further contain other photopolymerizable compounds. As the other photopolymerizable compound, a compound that copolymerizes with the alkyl α-allyloxymethylacrylate by light irradiation is preferable, a photoradical polymerizable compound is more preferable, and a (meth) acrylate compound is particularly preferable. These photopolymerizable compounds (B) may be used alone or in combination of two or more.
Other photopolymerizable compounds include, for example, benzyl (meth) acrylate, (ethoxy (or propoxy)) 2-phenoxyethyl (meth) acrylate, dicyclopentenyl (oxyethyl) (meth) acrylate, phenoxydiethylene glycol (meth). Acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, methoxydipropylene glycol (meth) acrylate, dipropylene glycol ( Meta) Acrylate, β-carboxyethyl (Meta) Acrylate, Trimethylol Propaneformal (Meta) Acrylate, Isoamyl (Meta) Acrylate, Cyclohexyl (Meta) Acrylate, Tetrahydrofurfuryl (Meta) Acrylate, Isobolonyl (Meta) Acrylate, Di Cyclopentanyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 1,4-cyclohexanedimethanol (meth) acrylate, 2-hydroxyethyl ( Meta) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, acryloylmorpholin, N-vinylcaprolactam, N-vinylpyrrolidone, N-vinylformamide, N-acryloyloxyethyl hexahydrophthalimide, etc. Monofunctional monomer; dimethylol tricyclodecanedi (meth) acrylate, (ethoxy (or propoxy)) bisphenol A di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate , (Ethoxy (or propoxy)) 1,6-hexanediol di (meth) acrylate, (ethoxy (or propoxy)) neopentyl glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, Dipropylene glycol di (meth) acrylate, (neopentyl glycol modified) trimethylpropandi (meth) acrylate, tripropylene glycol di (meth) acrylate, dicyclopentanyldi (meth) acrylate, pentaerythritol tri (or tetra) (Meta) acrylate, Polyfunctional monomers such as trimethylolpropane tri (or tetra) (meth) acrylate, tetramethylolmethanetri (or tetra) (meth) acrylate, and dipentaerythritol hexa (meth) acrylate; can be mentioned.

(Photopolymerizable compound having an amide group)
In the ink composition of the present invention, it is preferable to use a photopolymerizable compound having an amide group as another photopolymerizable compound. By combining an alkyl α-allyloxymethylacrylate and a photopolymerizable compound having an amide group, not only the effect of lowering the viscosity can be obtained, but also the photopolymerizability is improved.

The photopolymerizable compound having an amide group has an amide group and a radically polymerizable carbon-carbon double bond in one molecule, and the N-position may be substituted with an alkyl group or the like. The photopolymerizable compound having an amide group has not only low viscosity as a single substance but also excellent solubility and compatibility, so that the viscosity of the ink composition is lowered, the adhesion to the coating layer is improved, and the curability is improved. There are effects such as improvement. Further, when it is blended with quantum dots (A) or light scattering particles (D) described later, there is little possibility that their dispersibility is impaired or the viscosity increases, so that it can be used in a wide range of blending ratios and can be printed. It becomes easy to suppress excitation light transmission and increase external quantum efficiency while sufficiently maintaining aptitude and curability.

Examples of the photopolymerizable compound having an amide group include, but are not limited to, a (meth) acrylamide monomer and a lactam-based vinyl monomer.
Examples of the lactam-based vinyl monomer include N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone.
Examples of the (meth) acrylamide monomer include acrylamide, methacrylamide, and (meth) acrylamide having a substituent at the N-position, and preferably (meth) acrylamide having a substituent at the N-position. A typical example of a substituent at the N-position is an alkyl group, which may form a ring with the nitrogen atom of (meth) acrylamide, which ring is of carbon atom and (meth) acrylamide. In addition to the nitrogen atom, an oxygen atom may be included as a ring member. Further, a substituent such as alkyl or oxo (= O) may be bonded to the carbon atom constituting the ring.

Examples of N-substituted (meth) acrylamide include N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nn-butyl (meth) acrylamide, and Nt-. N-alkyl (meth) acrylamide such as butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-dodecyl (meth) acrylamide, Nt-octyl (meth) acrylamide; N, N-dimethyl (meth) Examples include N, N-dialkyl (meth) acrylamide such as acrylamide, N, N-diethyl (meth) acrylamide.

The N-substituted group, that is, the substituent on the nitrogen atom may be an alkyl group having a hydroxyl group, for example, N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N-. Examples include (2-hydroxypropyl) (meth) acrylamide.
The N-substituted group may be an alkyl group having an amino group, for example, dimethylaminomethyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide. Examples thereof include dialkylaminoalkyl (meth) acrylamide in which the hydrogen atom of the alkyl group in N-alkyl (meth) acrylamide is replaced with a dialkylamino group.
The N-substituent may be a substituent having an aromatic ring or an oxygen atom other than the above, and may be, for example, N-phenyl (meth) acrylamide, N- (butoxymethyl) (meth) acrylamide, diacetone (meth) acrylamide. , 2- (Meta) acrylamide-2-methylpropanesulfonic acid, 6- (meth) acrylamidehexanoic acid.
Further, specific examples of the N-substituted (meth) acrylamide forming the above-mentioned 5-membered ring or 6-membered ring include N-acryloylpyrrolidine, 3-acryloyl-2-oxazolidinone, 4-acryloylmorpholine, N-acryloylpiperidin, and the like. Examples thereof include N-methacryloylpiperidin.

Among these amide monomers, N, N-dialkyl (meth) acrylamide or dialkylaminoalkyl (meth) acrylamide is preferable from the viewpoint of the effect of reducing the viscosity of the ink composition, and specific examples thereof are dimethylacrylamide, diethylacrylamide, and dimethyl. Examples thereof include aminomethylacrylamide, dimethylaminoethylacrylamide, diethylaminoethylacrylamide, and dimethylaminopropylacrylamide. Of these, N, N-dialkyl (meth) acrylamide is preferable from the viewpoint of viscosity lowering effect.

The content of the photopolymerizable compound having an amide group is preferably 10 to 70% by mass, more preferably 15 to 50% by mass, still more preferably 20 to 20 to 70% by mass, based on the total amount of the photopolymerizable compound (B). It is 40% by mass. When it is 10% by mass or more, it is preferable because it is more excellent in viscosity reduction and photopolymerizability. When it is 70% by mass or less, the curability and adhesion of the coated matter and the printed matter are good, which is preferable.

[Photopolymerization Initiator (C)]
The ink composition further comprises a photopolymerization initiator. By including the photopolymerization initiator, the printed matter formed from the ink composition of the present invention can be cured by ultraviolet irradiation. The photopolymerization initiator is preferably a photoradical polymerization initiator, and the type thereof is not limited, and the photopolymerization initiator may be used alone or in combination of two or more.

Examples of the photoradical polymerization initiator include acetphenone compounds, benzoin compounds, benzophenone compounds, thioxanthone compounds, triazine compounds, oxime ester compounds, phosphine compounds, quinone compounds, borate compounds, and carbazole compounds. , Imidazole-based compounds, or titanosen-based compounds, and examples of commercially available acetphenone-based compounds include "Omnirad 907" (2-methyl-1- [4- (methylthio) phenyl] manufactured by IGM Resins B.V.]. -2-morpholinopropan-1-one), "Omnirad 369" (2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1 -Butanone), "Omnirad 379" 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1-one; as a commercially available phosphine compound, manufactured by IGM Resins B.V. "Omnirad 819" (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide), "Omnirad TPO H" (2,4,6-trimethylbenzoyldiphenylphosphine oxide) and the like can be mentioned.

The photopolymerization initiator (C) may be further combined with a sensitizer. Examples of the sensitizer include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl P-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine and 4, Examples thereof include amines such as 4'-bis (diethylamino) benzophenone.
The total amount of the photopolymerization initiator (C) and the sensitizer is preferably in the range of 1 to 15% by mass with respect to the total solid content of the ink composition. When it is 1% by mass or more, curing failure is unlikely to occur, and when it is 15% by mass or less, the influence of reaction residues and the like on various physical properties after curing is reduced, which is preferable.

[resin]
The ink composition of the present invention may contain a resin, if necessary. Examples of the resin include petroleum-based resin, maleic acid resin, nitrocellulose, cellulose acetate butyrate, cyclized rubber, rubber chloride, alkyd resin, acrylic resin, polyester resin, amino resin, vinyl resin, butyral resin, and 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, Examples thereof include polyethylene naphthalate (PEN) resin and fluorinated aromatic polymer resin.
The resin includes an epoxy resin, an oxetane group-containing resin, an isocyanate group-containing resin, a carboxyl group-containing resin, a thermosetting resin such as an allyl ester-based curable resin, or a silsesquioxane-based ultraviolet curable resin. An ultraviolet curable resin may be used.

The mass average molecular weight (Mw) of the resin is preferably 1,000 to 50,000, and when the ink composition is printed by the inkjet method, it is 3,000 to 45,000 from the viewpoint of ejection stability. Is more preferable. When the mass average molecular weight is 1,000 or more, the resistance of the film obtained from the ink composition is improved, and when the mass average molecular weight is 50,000 or less, the viscosity of the ink composition is within the appropriate viscosity range of the inkjet method. This is preferable because it can prevent clogging of the inkjet head and deterioration of ejection properties. The mass average molecular weight can be determined as a styrene-equivalent molecular weight by gel permission chromatography.

When a resin is contained, the content of the resin is preferably 15% by mass or less with respect to the total solid content of the ink composition. Within the above range, an optical wavelength conversion layer having good scratch resistance and chemical resistance can be obtained without increasing the viscosity too much. Further, when the ink composition is printed by an inkjet method to form an optical wavelength conversion layer, the viscosity of the ink composition is within an appropriate viscosity range of the head, so that head clogging and deterioration of ejection property can be prevented.

[Light scattering particles (D)]
The ink composition of the present invention may further contain light scattering particles (D). The light scattering particles (D) can substantially extend the optical path length by scattering light in the light wavelength conversion layer, and can improve the light absorption efficiency of the quantum dots. Examples of the photosynthetic scattering particles (D) include inorganic white pigments, organic white pigments, and polymer fine particles.
Examples of the inorganic white pigment include metal oxides such as titanium oxide, zinc oxide and alumina; carbonates of alkaline earth metals such as calcium carbonate; silicic acid, calcium silicate, lead white, talc and clay. Examples of the organic white pigment include a bisstyryl derivative white pigment and an alkylene bismelamine derivative white pigment.

Among them, as the light scattering particles (D), a metal oxide is preferable, and titanium oxide is more preferable. Titanium oxide has crystal forms such as rutile type, anatase type, and blue kite type, and the rutile type having low light transmission and high concealing property is preferably used. Further, titanium oxide may be surface-treated, and known surface treatment methods and surface treatment agents can be arbitrarily used.
Commercially available titanium oxide products include "Tapake CR-50, 50-2, 57, 80, 90, 93, 95, 953, 97, 60, 60-2, 63, 67, 58, 58-" manufactured by Ishihara Sangyo Co., Ltd. 2,85 "" Typake R-820,830, 930, 550, 630, 680, 670, 580, 780, 780-2, 850, 855 "" Typake A-100, 220 "" Typake W-10 "" Typake 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","Titanics JR-301, 403, 405, 600A, 605, 600E, 603, 805, 806, 701, 800, 808" manufactured by TAYCA Corporation. Examples thereof include "Titanics JA-1, C, 3, 4, 5" and "Typure R-900, 902, 960, 706, 931" manufactured by DuPont.

The average particle size when the light scattering particles (D) are dispersed in the ink composition is preferably 50 to 500 nm, more preferably 100 to 350 nm. When the average particle size is 50 nm or more, not only the dispersion stability of the light scattering particles is good and the storage stability of the ink composition is excellent, but also a sufficient scattering effect can be obtained, which is preferable. It is preferable that the average particle size is 500 nm or less because the inkjet ejection property is excellent.

[Dispersant]
The ink composition of the present invention may contain a dispersant in order to improve the dispersion stability of the light scattering particles (D) and the storage stability of the ink composition. Examples of the dispersant include a basic dispersant, an acidic dispersant, a neutral dispersant, and the like. Specifically, a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high-molecular-weight acid ester, and a high-molecular-weight polycarboxylic acid. Acid salt, long-chain polyaminoamide and polar acid ester salt, high molecular weight unsaturated acid ester, high molecular weight copolymer, modified polyurethane, modified polyacrylate, polyether ester type anionic activator, naphthalene sulfonic acid formarin condensate Salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphates, polyoxyethylene nonylphenyl ethers, stearylamine acetate and the like can be used.
The content of the dispersant is preferably 3 to 50% by mass with respect to the light scattering particles (D). Within the above range, dispersion stability and viscosity can be in a good range.

[solvent]
The ink composition may further contain a solvent. The solvent is not particularly limited, and for example, alkylene glycol monoalkyl ethers, diethylene glycol monoalkyl ethers, diethylene glycol dialkyl ethers, triethylene glycol monoalkyl ethers, triethylene glycol dialkyl ethers, tetraethylene glycol monoalkyl ethers. , Tetraethylene glycol dialkyl ethers, alkylene glycol alkyl ether acetates, aromatic hydrocarbons, ketones, alcohols, esters, cyclic esters and the like. These solvents may be used alone or in combination of two or more.

The solvent can be selected according to the application, and in the case of inkjet ink, it is selected from the viewpoints of solubility in quantum dots and polymerizable compounds, swelling action on equipment members, viscosity and drying property in nozzles, and has a boiling point of 100 ° C. As described above, it is more preferable to contain a solvent having a temperature of 130 ° C. or higher. The content of the solvent is preferably 0 to 50% by mass in the ink composition.

[Polymerization inhibitor]
The ink composition may contain a polymerization inhibitor to enhance storage stability. Examples of the polymerization inhibitor include aluminum salts of 4-methoxyphenol, hydroquinone, methylhydroquinone, t-butylhydroquinone, 2,5-t-butyl-4-methylphenol, phenothiazine, and N-nitrosophenylhydroxylamine. ..
The content of the polymerization inhibitor is preferably 0.01 to 0.1% by mass with respect to the solid content of the ink composition from the viewpoint of improving stability while maintaining curability.

[Other ingredients]
In order to enhance printability and print resistance, the ink composition may further contain additives such as a surface conditioner, a leveling agent, an ultraviolet absorber or an antioxidant, if necessary.

<Adjustment of ink composition>
The ink composition of the present invention can be prepared according to a well-known method. For example, when the light scattering particles (D) are used, the light scattering particles (D) are previously dispersed with a small amount of solvent, the polymerizable compound (B), a dispersant, or the like, and then the remaining components are added and mixed, and the photopolymerization initiator (C) is used. ) Can be dissolved. At this time, in order to prevent clogging in the printer head during printing, it is preferable to filter with a filter having a pore size of 5 μm or less, preferably 3 μm or less after the photopolymerization initiator (C) is dissolved.

The ink composition of the present invention preferably has a viscosity at 25 ° C. of 5 to 50 mPa · s, more preferably 5 to 30 mPa · s. By adjusting the viscosity of the ink composition to the above range, it is stable not only in a normal head having a frequency of 5 to 30 KHz but also in a head having a high frequency of 10 to 50 KHz, especially when used in the form of an inkjet ink. It is possible to obtain the discharged characteristics.

<How to use>
The method of using the ink composition of the present invention is not particularly limited, but it can be used as an ink for a normal inkjet recording printer. Typical methods include a step of supplying the ink composition to the head of an inkjet recording printer, a step of ejecting the ink composition from the head onto the substrate, and then ultraviolet rays to the ink composition on the substrate. Alternatively, it includes a step of irradiating an active energy ray such as an electron beam. By irradiation with active energy rays, the ink composition on the substrate is rapidly cured and a printed surface is formed.

Ultraviolet rays are preferable as the active energy rays, and for example, high-pressure mercury lamps, metal halide lamps, low-pressure mercury lamps, ultra-high pressure mercury lamps, ultraviolet lasers, gallium lamps, LEDs, and sunlight can be used as light sources.
The wavelength of ultraviolet rays is preferably in the range of 350 to 450 nm, and the irradiation amount of ultraviolet rays is preferably in ^{the range of 10 to 10000 mJ / cm 2} , and any of the generally widely used metal halide lamps and LED lamps can be used. You may use it.

<Laminated body>
The laminate of the present invention has a plurality of layers, and at least one layer includes a light emitting layer made of the ink composition of the present invention.
In particular, when it is desired to impart a plurality of functions to a film-like member, or when it is desired to further improve the performance of the light emitting layer of the present invention, it is better to separate the functions from the top and bottom than to give the single layer various functions in a well-balanced manner. In many cases, it is advantageous in terms of process and performance. The layer formed by using the ink composition of the present invention in the laminate is a light emitting layer, and the upper and lower layers include a light emitting layer (with different light emitting colors), a light absorbing layer, a light scattering layer, and a light reflecting layer. A wide variety of functional layers such as a light reflection prevention layer, a conductor layer, a dielectric layer, a heat conduction layer, a heat shield layer, and a barrier layer such as water and oxygen are assumed. Since the ink composition of the present invention is an active energy ray-curable type, even if the film formation of the upper and lower layers is a solvent coating type, the possibility of invading the lower layer during the film formation of the upper layer is small, and the laminate is relatively thin. It can be easily produced.

<Light wavelength conversion layer>
The layer formed by curing after coating and printing using the quantum dot-containing ink composition of the present invention can be used as an optical wavelength conversion layer. The optical wavelength conversion layer can convert the excitation light into fluorescence on the long wavelength side and emit it, and there is no particular limitation as long as the relationship between the excitation light wavelength and the emitted fluorescence wavelength can be maintained. Fluorescence of green or red can be obtained from the excitation light of. In addition, fluorescence in the near infrared region can be obtained from excitation light of ultraviolet light or visible light.

As a method for coating and printing the ink composition, a spray method such as a spray method or an inkjet method, a spin coating method, a bar coater method, a doctor blade method or the like can be used.

The method for curing the ink composition is not particularly limited, and a method of ultraviolet curing or thermosetting is preferably used. As for ultraviolet curing, for example, after applying an ink composition on a base material layer, ultraviolet rays are irradiated with an irradiation intensity of 80 to 120 W and an integrated light amount of 500 to 2000 mJ (UVA equivalent) using a high-pressure mercury lamp, a metal halide lamp, or the like. And cure. From the viewpoint of suppressing deterioration of quantum dots, ultraviolet curing is preferably performed in a low oxygen environment, more preferably in an atmosphere having an oxygen concentration of 300 ppm or less.
Examples of the thermosetting include a method in which the ink composition is applied on the base material layer, the solvent is volatilized by heat treatment, and then the thermosetting is performed. The heating step for volatilizing the solvent is preferably performed at 120 ° C. or lower within 5 minutes, and more preferably at 100 ° C. or lower within 2 minutes. The thermosetting treatment is preferably performed at 80 ° C. or lower within 3 days, and more preferably at 60 ° C. or lower within 24 hours. The conditions for ultraviolet curing and thermosetting are not limited to the above because the optimum conditions differ depending on the quantum dots used, the polymerizable compound, the resin, and the like.

The thickness of the optical wavelength conversion layer is preferably 1 to 500 μm, more preferably 1 to 50 μm, and even more preferably 1 to 10 μm. A thickness of 1 μm or more is preferable because a high wavelength conversion effect can be obtained. When the thickness is 500 μm or less, the light source unit can be thinned when incorporated in the light source unit, which is preferable.

<Light wavelength conversion member>
The light wavelength conversion member includes a light wavelength conversion layer on at least one surface of the base material. The base material is not particularly limited, and is a plastic base material such as polycarbonate, hard vinyl chloride, soft vinyl chloride, polystyrene, foamed styrol, polymethylmethacrylate, polypropylene, polyethylene, polyethylene terephthalate, mixed or modified products thereof, high-quality paper, art paper. , Coated paper, paper base material such as cast coated paper, metal base material such as glass and stainless steel, and the like. The base material is appropriately selected according to the intended use, and for applications such as prepaid cards and passing cards, a plastic base material or a mixed or modified product thereof is preferably used from the viewpoint of durability. For applications such as a one-dimensional bar code, a two-dimensional bar code, and a QR code (registered trademark) as an information recording medium, a paper base material is preferably used in addition to the plastic base material. For wavelength conversion color filter applications, a transparent substrate is preferable.
The transparent substrate preferably has a transmittance of 85% or more in the wavelength range of 380 to 1000 nm, and is, for example, a glass plate such as soda-lime glass, low-alkali borosilicate glass, or non-alkali aluminum borosilicate glass. , Polycarbonate, polymethyl methacrylate, polyethylene terephthalate and the like.
The thickness of the base material is not particularly limited and can be appropriately selected depending on the intended use. When the thickness of the base material is 20 μm or more, the shape of the light wavelength conversion layer can be easily maintained, and when it is 2 mm or less, the transparency of the base material is maintained, which is preferable.

Further, the light wavelength conversion member may have a barrier layer. The method for producing the light wavelength conversion member having a barrier layer is not particularly limited. For example, an ink composition is applied onto a substrate and cured to form a light wavelength conversion layer, and then an oxygen gas barrier coat is applied onto the light wavelength conversion layer. A method of applying an agent and curing it to obtain a light wavelength conversion member, an ink composition is applied on a base material layer and cured to form a light wavelength conversion layer, and then the light wavelength conversion layer is coated with an adhesive layer. Examples thereof include a method of obtaining an optical wavelength conversion member by laminating an oxygen gas barrier film. Examples of the method for applying the oxygen gas barrier coating agent include the same method as for the ink composition.

<Wavelength conversion film><Colorfilter>
The ink composition of the present invention can be used to form a wavelength conversion film or a color filter.
Wavelength conversion films and color filters are used to absorb light from a light source and extract light of a desired wavelength by unabsorbed transmitted light or fluorescence emission generated by light absorption, and use quantum dots. In this case, fluorescence emission with an excellent quantum yield will be used. The wavelength conversion film is a coating or printing film obtained by applying an ink composition to a base material and containing quantum dots that emit green and red fluorescent colors, and is mainly used as a light source in a display panel or lighting. It is a flat member that converts blue light into white light or adjusts pseudo-white light having an irregular color tone to a desired color tone. Examples of the base material include a glass plate and a resin plate.

The color filter of the present invention is obtained by forming at least one segment of a filter segment using an ink composition, and is particularly used for a liquid crystal display panel. Specifically, three or more kinds of fine striped filter segments having different hues are arranged in parallel or intersecting on the surface of a transparent substrate such as glass, or fine mosaic-shaped filter segments are fixed in length and width. It consists of those arranged in an array. In the present invention, unlike the light absorption type color filter that extracts blue, green, and red light from a conventional white light source, green and red are extracted mainly by using a blue LED or the like as a light source and a fluorescent filter. When quantum dots are used, energy loss is reduced because the fluorescence is extracted with high quantum yield instead of dimming due to light absorption, and the wavelength distribution is narrow and colors close to pure colors can be obtained, resulting in a highly efficient display. It can be manufactured. At this time, if the quantum dots that emit green and red fluorescence are those having high absorbance in the blue light portion using the coating material of the present invention, they can be efficiently converted to fluorescence and the original blue light can be converted. Since it is possible to prevent omission, it is possible to obtain a filter having high color purity without using a dye or a light scattering substance that absorbs blue separately.

<Light emitting device>
A light emitting device can be obtained by combining the light emission length conversion member of the present invention and a light emitting element. The light emitting device may have a known configuration, and the light wavelength conversion member and the light emitting element may be in close contact with each other, may be separated from each other, may be provided with a transparent resin between them, and have a space. You may. The light emitting element is not particularly limited, and examples thereof include a light emitting diode element (LED element), a laser diode element (LD element), an organic electroluminescence element (organic EL element), and a quantum dot element (QLED element).

Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto. Unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass".

<Manufacturing of quantum dots>
(Quantum dot 1)
0.55 parts of acetic anhydride, 7.0 parts of dodecanethiol, and 5.0 parts of oleylamine were dissolved by heating 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 200 ° C. while performing nitrogen bubbling. After the indium chloride was dissolved, 0.86 part of dimethylaminophosphine was injected in a short time and controlled at 200 ° C. for 20 minutes. After that, it was rapidly cooled and cooled to 40 ° C. The above additive solution was injected, heated at 240 ° C. for 2 hours, and then allowed to cool to room temperature. After allowing to cool, purification was carried out by a reprecipitation method using hexane and ethanol, and the mixture was dried in a vacuum dryer at room temperature for 1 day to obtain a solid of quantum dots 1 having a core containing indium and phosphorus.

(Quantum dot 2)
0.55 parts of acetic anhydride, 7.0 parts of dodecanethiol, and 5.0 parts of oleylamine were dissolved by heating 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 200 ° C. while performing nitrogen bubbling. After the indium chloride was dissolved, 0.86 part of dimethylaminophosphine was injected in a short time and controlled at 200 ° C. for 20 minutes. After that, it was rapidly cooled and cooled to 40 ° C. The above additive solution was injected, heated at 240 ° C. for 2 hours, and then allowed to cool to room temperature. After allowing to cool, purification was carried out by a reprecipitation method using hexane and ethanol to obtain a quantum dot intermediate. Next, the quantum dot intermediate was diluted in toluene to a solid content concentration of 1%, and the same amount of a 5% toluene solution of 6- (diethylamino) -1,3,5-triazine-2,4-dithiol was added. , Stirred for 12 hours. Purification was carried out by a reprecipitation method using toluene and ethanol, and the mixture was dried in a vacuum dryer at room temperature for 1 day to obtain a solid of quantum dots 2 having a core containing indium and phosphorus.

(Quantum dot 3)
Solution A: 0.18 parts of lead oxide, 0.13 parts of cesium hydroxide monohydrate, and 3.58 parts of oleic acid were added to a general-purpose container substituted with nitrogen, heated until dissolved, and then cooled to room temperature.
Solution B: 0.44 parts of tetraoctylammonium bromide, 0.90 parts of oleic acid, and 3.5 parts of toluene were stirred and dissolved.
Liquid A and liquid B were mixed in 20 seconds to generate microcrystals. The crystallites were purified using ethanol, acetone and toluene, and dried in a vacuum dryer at room temperature for 1 day to obtain a solid of quantum dots 3 having the chemical formula of _{CsPbBr 3.}

<Manufacturing of light scattering particle dispersion>
(Light scattered particle 1 dispersion)
A mixture consisting of 50 parts of JR-603 (manufactured by TAYCA Corporation, average particle size 280 nm), 2 parts of Solspurs 32000 (polymer dispersant manufactured by Lubrizol), and 48 parts of phenoxyethyl acrylate as titanium oxide, and zirconia beads (diameter:: 1.25 mm) was added, and the mixture was shaken for 2 hours using a paint conditioner to carry out a dispersion treatment. Next, the dispersion was filtered through a nylon mesh filter to remove zirconia beads, and a dispersion of light scattering particles 1 containing a polymerizable monomer was obtained.

(Light scattering particles 2)
Thermosetting resin spherical fine particles (“Eposter S6” manufactured by Nippon Catalyst Co., Ltd., average particle diameter 0.4 μm, refractive index 1.66), which is a melamine-formaldehyde condensate, were used as the light scattering particles 2.

<Manufacturing of active energy ray-curable ink composition>
[Examples 1 to 10, Comparative Example 1]
(Inkjet ink (QDIJ-1 to 11))
The materials listed in Table 1 are sequentially added and mixed with stirring, and after sufficiently stirring until the photopolymerization initiator is dissolved, the mixed solution is filtered using a membrane filter having a pore size of 1 μm to obtain inkjet inks (QDIJ-1 to 11). ) Was obtained.
Unless otherwise specified, the numerical values in Table 1 represent "parts", and blanks mean that they are not mixed.

<Evaluation of active energy ray-curable ink composition>
The obtained ink composition was evaluated as follows. The results are shown in Table 1.

[viscosity]
The ink composition was kept warm at 25 ° C. in a constant temperature bath, and then the viscosity (mPa · s) was measured using a laboratory vibration viscometer VM-10A manufactured by SECONIC.

[Continuous discharge]
The ink composition was filled in a cartridge and inkjet printing was performed, and the continuous ejection property was evaluated according to the following criteria. The inkjet printing conditions are as follows.
≪Inkjet ejection test conditions≫
Printing machine: FUJIFILM Dynamics Printer
Cartridge: DynamicsMaterialsCartriges 10pL
Head drive voltage: 25V
Head drive temperature: 30 ° C
Base material: Glass substrate (Corning glass "Eagle XG" 0.7 mm thick)
≪Evaluation criteria≫
A: Continuous discharge time is 30 minutes or more (good)
B: Continuous discharge time is 10 minutes or more and less than 30 minutes (usable)
C: Continuous discharge time is less than 10 minutes (cannot be used)

[UV curability]
The ink composition is applied to a glass substrate (Corning glass "Eagle XG", thickness 0.7 mm) using bar coater # 5, a high-pressure mercury lamp 80 W using a UV irradiator, and an integrated light amount of 500 mJ (UVA equivalent). The coating film was cured by irradiating with ultraviolet rays, and evaluated according to the following criteria.
A: There is no tack on the cured film (good)
B: Hardened film, but slight tack remains (usable)
C: Does not cure (cannot be used)

[Wavelength conversion efficiency]
The ink composition is applied to a glass substrate (Corning glass "Eagle XG", thickness 0.7 mm) using a bar coater # 5, cured under the same conditions as the UV curability evaluation, and a cured film having a thickness of 6 μm. Got The external quantum efficiency (EQE) of this cured film was measured and evaluated as the wavelength conversion efficiency according to the following criteria. The external quantum efficiency was measured using QE-2000 manufactured by Otsuka Electronics Co., Ltd., with an excitation wavelength of 450 nm and an integration range of fluorescence wavelength of 500 nm to 800 nm.
A: Less than 10% (good)
B: 10% or more and less than 20% (usable)
C: 20% or more (cannot be used)

The abbreviations in Table 1 are shown below.
Omnirad 907 (IGM Resin B.V. Photopolymerization Initiator α-Aminoalkylphenone)
KAYACURE DETX-S (Nippon Kayaku Co., Ltd. Photopolymerization Initiator 2,4-diethylthioxanthone)
BYK-378 (Silicon surface conditioner manufactured by BYK-Chemie GmbH)

According to the results in Table 1, the ink composition of the present invention containing an alkyl α-allyloxymethylacrylate has a low viscosity and can be adjusted to a viscosity capable of inkjet ejection even when the ratio of quantum dots is increased. is there. Further, the layer obtained from the composition is excellent in wavelength conversion efficiency.

The printed matter printed using the ink composition of the present invention can be suitably used for color filters, light conversion layers, solar cells, lasers, fluorescent labels and the like. Furthermore, by using the fluorescence response at a specific wavelength, it is possible to give security to brand labels, one-dimensional barcodes, two-dimensional barcodes, QR codes (registered trademarks), symbol marks, etc., and to change the wavelength of the light source. By switching, it becomes possible to print the multiplexing information. As described above, a high authenticity authentication effect and anti-counterfeiting effect can be expected by using light emission at a specific wavelength.

Claims (13)

An ink composition containing a quantum dot (A), a photopolymerizable compound (B) containing an alkyl α-allyloxymethylacrylate, and a photopolymerization initiator (C). The ink composition according to claim 1, wherein the content of the quantum dots (A) is 10% by mass or more and 50% by mass or less in the total solid content in the composition. The ink composition according to claim 1 or 2, wherein the content of the alkyl α-allyloxymethylacrylate is 5% by mass or more and 40% by mass or less based on the total solid content in the composition. The ink according to any one of claims 1 to 3, wherein the content of the alkyl α-allyloxymethylacrylate is 10% by mass or more and 35% by mass or less based on the total amount of the photopolymerizable compound (B). Composition. The ink composition according to any one of claims 1 to 4, wherein the photopolymerizable compound (B) further contains a photopolymerizable compound having an amide group. The ink composition according to any one of claims 1 to 5, further containing light scattering particles (D). The ink composition according to claim 6, wherein the light scattering particles (D) are particles made of a metal oxide. The ink composition according to any one of claims 1 to 7, wherein the viscosity at 25 ° C. is in the range of 5 to 30 mPa · s. The ink composition according to any one of claims 1 to 8, which is used for an active energy ray-curable inkjet ink. A laminate having a plurality of layers, wherein at least one layer has a light emitting layer composed of the ink composition according to any one of claims 1 to 9. An optical wavelength conversion layer comprising the ink composition according to any one of claims 1 to 9. The light wavelength conversion member having the light wavelength conversion layer according to claim 11. A color filter comprising a filter segment formed on a base material using the ink composition according to any one of claims 1 to 9.