WO2022107602A1

WO2022107602A1 - Dispersion, optical conversion layer, color filter, and light-emitting element

Info

Publication number: WO2022107602A1
Application number: PCT/JP2021/040514
Authority: WO
Inventors: 浩一延藤; 雅弘堀口; 祐貴野中; 良夫青木
Original assignee: Dic株式会社
Priority date: 2020-11-18
Filing date: 2021-11-04
Publication date: 2022-05-27
Also published as: JP2022080617A

Abstract

The problem to be solved by the present invention is to provide a luminescent particle dispersion having exceptional optical characteristics and dispersibility of luminescent particles in which semiconductor nanocrystals formed from a metal halide are encapsulated in silica particles. The present invention solves the aforementioned problem by providing a luminescent particle dispersion containing luminescent particles that have hollow silica particles having an inside space and semiconductor nanocrystal particles formed from a metal halide accommodated in the inside space, a photopolymerizable compound having an SP value of 10.0 or less, and a block copolymer equipped with a first structural unit having a basic group and a second structural unit having an affinity for the photopolymerizable compound.

Description

Dispersion, optical conversion layer, color filter and light emitting device

The present invention relates to a dispersion, an optical conversion layer, a color filter and a light emitting device.

In recent years, there has been a strong demand for higher color gamut of displays. Therefore, a color having a pixel portion such as a red pixel or a green pixel using luminescent nanocrystal particles such as quantum dots, quantum rods, and other inorganic phosphor particles instead of the red organic pigment particles or the green organic pigment particles. Research on filters is becoming more active. Since it is desired that the color filter has a fine pattern and the photolithography method wastefully consumes luminescent nanocrystal particles, an inkjet method (inkjet method) using an ultraviolet curable ink composition is used. It is being studied to form an optical conversion layer. For example, Patent Document 1 describes an ink composition for inkjet containing luminescent nanocrystal particles composed of core / shell type semiconductor nanocrystals and a photopolymerizable compound having an amide group, and a cured film of the composition. The wavelength conversion member is disclosed. However, when a core / shell type semiconductor nanocrystal is used as an optical conversion material, strict particle size control of the core portion and the shell portion is required in order to adjust the emission wavelength range, and the ink is industrially stable in quality. The difficulty of producing is high.

Therefore, as inorganic luminescent particles whose particle size can be adjusted relatively easily, in recent years, semiconductor crystals made of metal halide, particularly compounds represented by CsPbX ₃ (X represents Cl, Br or I) have been used. Semiconductor nanocrystals having a typified perovskite-type crystal structure have been found and are attracting attention (for example, Patent Document 2).

However, when the core / shell type semiconductor nanocrystal particles in the ink composition for inkjet are to be replaced with the perovskite type semiconductor crystal particles, the perovskite type semiconductor nanocrystals are destabilized by a polar solvent such as water. It is easy and may cause a decrease in quantum yield. To solve the problem of stabilizing perovskite-type semiconductor crystal particles, for example, a technique for stabilizing the semiconductor nanocrystals by encapsulating the perovskite-type semiconductor nanocrystals with a SiOx spherical matrix has been proposed. (See Patent Document 3).

Japanese Unexamined Patent Publication No. 2020-079676 Special Table 2018-506625 U.S. Patent Application Publication No. 2018/0002354

However, even if a perovskite-type semiconductor nanocrystal encapsulated in a SiOx spherical matrix is used in an ink jet ink composition, dispersants and ligands generally used in the ink composition have high polarities and are therefore dispersed. Since the agent or ligand itself takes in water in the atmosphere, the stabilizing effect by encapsulation becomes insufficient. On the other hand, when perovskite-type semiconductor nanocrystals are used without encapsulation in a SiOx spherical matrix, the dispersibility is good, but as described above, the stability is impaired by moisture and the optical characteristics are sacrificed. be.

Therefore, an object to be solved by the present invention is to provide a luminescent particle dispersion having excellent optical properties and dispersibility of luminescent particles containing semiconductor nanocrystals made of metal halide in silica particles. Further, it is an object of the present invention to provide an optical conversion layer, a color filter and a light emitting element using the luminescent particle dispersion.

The luminescent particle dispersion of the present invention has luminescent particles including hollow silica particles having an inner space and semiconductor nanocrystal particles made of metal halide contained in the inner space, and a solubility parameter (SP value). A photopolymerizable compound of 10.0 or less, and a block copolymer having a first structural unit having a basic group and a second structural unit having an affinity for the photopolymerizable compound. It is characterized by containing.

The photopolymerizable compound preferably contains at least one monofunctional (meth) acrylate.

The amine value of the block copolymer is preferably 2 mgKOH / g or more and 70 mgKOH / g or less.

The luminescent particle dispersion may further contain a photopolymerization initiator.

The luminescent particle dispersion may further contain light scattering particles.

The luminescent particle dispersion is preferably used as an ink jet ink.

The optical conversion layer of the present invention includes a plurality of pixel portions and a light-shielding portion provided between the plurality of pixel portions, and the plurality of pixel portions emit light including a cured product of the above-mentioned luminescent particle dispersion. It is characterized by having a sex pixel portion.

The color filter of the present invention is characterized by including the above-mentioned optical conversion layer.

The light emitting element of the present invention is characterized by including the above color filter.

According to the present invention, it is possible to provide a luminescent particle dispersion having excellent optical properties and dispersibility of luminescent particles containing semiconductor nanocrystals made of metal halide in silica particles. Further, it is possible to provide an optical conversion layer, a color filter, and a light emitting element using the luminescent particle dispersion.

FIG. 1 is a schematic cross-sectional view of a color filter according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments.

<Luminous particle dispersion>
One embodiment of the present invention comprises luminescent particles including hollow silica particles having an inner space and semiconductor nanocrystal particles composed of metal halide contained in the inner space, and a solubility parameter (SP value) of 10. It contains a photopolymerizable compound of 0 or less, and a block copolymer having a first structural unit having a basic group and a second structural unit having an affinity for the photopolymerizable compound. It is a luminescent particle dispersion. Hereinafter, the luminescent particle dispersion may be simply referred to as "dispersion".

<< Luminous particles >>
The luminescent particles are particles in which a crystal (semiconductor nanocrystal particles) composed of metal halide and having a particle size capable of absorbing excitation light and emitting fluorescence or phosphorescence is contained in the internal space of the hollow silica particles. Since the nanocrystal particles are contained inside the hollow particles, the stability of the luminescent particles with respect to oxygen gas and moisture can be improved, and thereby the optical characteristics can also be improved. As the luminescent nanocrystal made of metal halide, for example, a semiconductor nanocrystal having a perovskite-type crystal structure described later is preferable.

As a method of accommodating the semiconductor nanocrystals made of metal halide in the inner space of the hollow silica particles, for example, the hollow silica particles are impregnated with a solution containing the raw material compound of the nanocrystal particles and dried to inside the hollow silica particles. It can be obtained by precipitating nanocrystal particles in the space.

The hollow silica particles may be spherical (true spherical), elongated spherical (elliptical spherical), or rectangular parallelepiped (including cube). Hollow silica particles can also be referred to as particles having a balloon structure. One semiconductor nanocrystal particle may be present in the inner space, or a plurality of semiconductor nanocrystal particles may be present. Further, the inner space may be entirely occupied by one or a plurality of nanocrystal particles, or may be partially occupied.

The average outer diameter of the hollow silica particles is not particularly limited, but is preferably 5 nm or more, more preferably 6 nm or more, further preferably 8 nm or more, particularly preferably 10 nm or more, preferably 300 nm or less, and more preferably 100 nm or less. It is more preferably 50 nm, and particularly preferably 25 nm or less. Hollow silica particles having such an average outer diameter can sufficiently enhance the heat stability of the semiconductor nanocrystal particles. The average outer diameter of the hollow silica particles is determined as an average value of the outer diameters measured for 20 hollow silica particles, for example, in a transmission electron microscope (TEM) image.

The average inner diameter of the hollow silica particles is not particularly limited, but is preferably 1 nm or more, more preferably 2 nm or more, further preferably 3 nm or more, particularly preferably 5 nm or more, preferably 250 nm or less, more preferably 100 nm or less, and further. It is preferably 50 nm or less, and particularly preferably 15 nm or less. Hollow silica particles having such an average inner diameter can sufficiently enhance the heat stability of the semiconductor nanocrystal particles. The average inner diameter of the hollow silica particles is determined as the average value of the inner diameters measured for 20 hollow silica particles, for example, in a transmission electron microscope (TEM) image.

The size of the pores in the hollow silica particles is not particularly limited, but is preferably 0.5 nm or more, more preferably 1 nm or more, preferably 10 nm or less, and more preferably 5 nm or less. In this case, when producing the luminescent particles, the solution containing the raw material compound of the semiconductor nanocrystal particles can be smoothly and surely filled in the inner space of the hollow silica particles. The size of the pores in the hollow silica particles was measured by the pore distribution measuring device "BELSORP-miniX" (quantitative positive displacement gas adsorption method), analyzed according to the BJH method, and the peak top of the obtained pore distribution plot. Was the size of the pores.

Commercially available products can also be used for the hollow silica particles. Examples of such commercially available products include "Silinax (registered trademark) SP-PN (b)" manufactured by Nittetsu Mining Co., Ltd.

The semiconductor nanocrystal particles made of metal halide are composed of a compound represented by the general formula: A _a M _b X _c .
In the formula, A is at least one of an organic cation and a metal cation. Examples of the organic cation include ammonium, formamidinium, guanidinium, imidazolium, pyridinium, pyrrolidinium, protonated thiourea and the like, and examples of the metal cation include cations such as Cs, Rb, K, Na and Li.
M is at least one metal cation. Metal cations are selected from Group 1, Group 2, Group 3, Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11, Group 13, Group 14, and Group 15. Examples include cations. More preferably, Ag, Au, Bi, Ca, Ce, Co, Cr, Cu, Eu, Fe, Ga, Ge, Hf, In, Ir, Mg, Mn, Mo, Na, Nb, Nd, Ni, Os, Examples thereof include cations such as Pb, Pd, Pt, Re, Rh, Ru, Sb, Sc, Sm, Sn, Sr, Ta, Te, Ti, V, W, Zn, and Zr.
X is at least one anion. Examples of the anion include chloride ion, bromide ion, iodide ion, cyanide ion and the like, and include at least one halogen.
a is 1 to 4, b is 1 to 4, and c is 3 to 16.

The compound composed of a metal halide represented by the above general formula A _a M _b X _c is a compound to which metal ions such as Bi, Mn, Ca, Eu, Sb, and Yb are added (doped) in order to improve the light emission characteristics. May be.

Among the metal halides represented by the above general formula A _a M _b X _c , the compound having a perovskite type crystal structure adjusts its particle size, the type and abundance ratio of the metal cations constituting the M site, and further adjusts the X site. It is particularly preferable to use it as luminescent particles in that the emission wavelength (emission color) can be controlled by adjusting the type and abundance ratio of the constituent anions. Specifically, compounds represented by AMX ₃ , A ₃ MX ₅ , A ₃ MX ₆ , A ₄ MX ₆ , and A ₂ MX ₆ are preferable. A, M and X in the formula are as described above. Further, as described above, the compound having a perovskite-type crystal structure was added (doped) with metal ions such as Bi, Mn, Ca, Eu, Sb, and Yb, which are different from the metal cations used for the M site. It may be a thing.

In addition to the particle size of perovskite-type semiconductor nanocrystals, the emission wavelength can be controlled by adjusting the abundance ratio of halogen atoms. Since this adjustment operation can be easily performed, the perovskite type semiconductor nanocrystal has a feature that the emission wavelength is easier to control and therefore the productivity is higher than that of the conventional core-shell type semiconductor nanocrystal. ing.

Among the compounds showing a perovskite type crystal structure, A is Cs, Rb, K, Na, Li, and M is one kind of metal cation (M ¹ ) or two kinds, in order to show better emission characteristics. It is a metal cation (M ¹ _α M ² _β ), and X is preferably a chloride ion, a bromide ion, or an iodide ion. However, α and β each represent a real number of 0 to 1, and represent α + β = 1. Specifically, M may be selected from Ag, Au, Bi, Cu, Eu, Fe, Ge, K, In, Na, Mn, Pb, Pd, Sb, Si, Sn, Yb, Zn, and Zr. preferable.

As a specific composition of semiconductor nanocrystal particles made of metal halide showing a perovskite type crystal structure, semiconductor nanocrystal particles using Pb as M such as CsPbBr ₃ , CH ₃ NH ₃ PbBr ₃ , CHN ₂ H ₄ PbBr ₃ and the like are It is preferable because it has excellent light intensity and quantum efficiency. Further, semiconductor nanocrystal particles using a metal cation other than Pb as M such as CsSnBr ₃ and CsEuBr ₃ CsYbI ₃ are preferable because they have low toxicity and have little influence on the environment.

The semiconductor nanocrystal particles may be red light emitting crystals that emit light having an emission peak in the wavelength range of 605 to 665 nm (red light), and light having an emission peak in the wavelength range of 500 to 560 nm (green light). It may be a green light emitting crystal that emits light (blue light) having an emission peak in the wavelength range of 420 to 480 nm, and may be a blue light emitting crystal. Further, in one embodiment, a combination of these nanocrystals may be used.
The wavelength of the emission peak of the semiconductor nanocrystal particles can be confirmed, for example, in the fluorescence spectrum or the phosphorescence spectrum measured by using an absolute PL quantum yield measuring device.

Red light emitting semiconductor nanocrystal particles are 665 nm or less, 663 nm or less, 660 nm or less, 658 nm or less, 655 nm or less, 653 nm or less, 651 nm or less, 650 nm or less, 647 nm or less, 645 nm or less, 643 nm or less, 640 nm or less, 637 nm or less, 635 nm. Hereinafter, it is preferable to have an emission peak in the wavelength range of 632 nm or less or 630 nm or less, and have an emission peak in the wavelength range of 628 nm or more, 625 nm or more, 623 nm or more, 620 nm or more, 615 nm or more, 610 nm or more, 607 nm or more or 605 nm or more. Is preferable.
These upper and lower limit values can be combined arbitrarily. In the same description below, the upper limit value and the lower limit value described individually can be arbitrarily combined.

Green-emitting semiconductor nanocrystal particles emit light in the wavelength range of 560 nm or less, 557 nm or less, 555 nm or less, 550 nm or less, 547 nm or less, 545 nm or less, 543 nm or less, 540 nm or less, 537 nm or less, 535 nm or less, 532 nm or less, or 530 nm or less. It is preferable to have a peak, and it is preferable to have an emission peak in a wavelength range of 528 nm or more, 525 nm or more, 523 nm or more, 520 nm or more, 515 nm or more, 510 nm or more, 507 nm or more, 505 nm or more, 503 nm or more, or 500 nm or more.

Blue-emitting semiconductor nanocrystal particles emit light in the wavelength range of 480 nm or less, 477 nm or less, 475 nm or less, 470 nm or less, 467 nm or less, 465 nm or less, 463 nm or less, 460 nm or less, 457 nm or less, 455 nm or less, 452 nm or less, or 450 nm or less. It is preferable to have a peak, and it is preferable to have an emission peak in a wavelength range of 450 nm or more, 445 nm or more, 440 nm or more, 435 nm or more, 430 nm or more, 428 nm or more, 425 nm or more, 422 nm or more, or 420 nm or more.

The shape of the semiconductor nanocrystal particles is not particularly limited, and may be any geometric shape or any irregular shape. Examples of the shape of the semiconductor nanocrystal particles include a rectangular parallelepiped shape, a cubic shape, a spherical shape, a regular tetrahedron shape, an ellipsoidal shape, a pyramidal shape, a disk shape, a branch shape, a net shape, a rod shape and the like. As the shape of the semiconductor nanocrystal particles, a shape having less directionality (for example, a spherical shape, a regular tetrahedron shape, etc.) is preferable. By using semiconductor nanocrystal particles having such a shape, luminescent particles reflecting the shape can be obtained, and uniform dispersibility and fluidity when a dispersion containing such luminescent particles is prepared can be further enhanced.

The average particle diameter (volume average diameter) of the semiconductor nanocrystal particles is preferably 40 nm or less, more preferably 30 nm or less, and further preferably 20 nm or less. The average particle size of the semiconductor nanocrystal particles is preferably 1 nm or more, more preferably 1.5 nm or more, and further preferably 2 nm or more. Semiconductor nanocrystal particles having such an average particle size are preferable because they easily emit light having a desired wavelength.
The average particle size of the semiconductor nanocrystal particles is obtained by measuring with a transmission electron microscope or a scanning electron microscope and calculating the volume average diameter.

The content of the luminescent particles is preferably 0.1% by mass or more, more preferably 1% by mass or more, based on the total amount of the dispersion, from the viewpoint of improving the external quantum efficiency of the light emitting layer (light conversion layer). It is more preferably 2% by mass or more, and particularly preferably 3% by mass or more. The content of the luminescent particles is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass, based on the total amount of the dispersion, from the viewpoint of improving the ink ejection stability in the inkjet printing method. % Or less, particularly preferably 7% by mass or less.

<< Photopolymerizable compound >>
As the photopolymerizable compound, a compound having a solubility parameter (SP value) of 10.0 or less is used. Since such a photopolymerizable compound has high polarity, it can suppress hygroscopicity to a low level. Therefore, since the dispersion of the present embodiment and the cured product thereof can suppress deterioration of semiconductor nanocrystals made of metal halides constituting the luminescent particles due to moisture, excellent stability of the luminescent particles can be obtained. As a result, the optical characteristics are also improved.

From the viewpoint of further suppressing hygroscopicity and improving quantum efficiency, the SP value is more preferably 9.75 or less, and further preferably 9.50 or less. On the other hand, from the viewpoint of solubility of the luminescent particles and the block copolymer described later, it is preferably 8.50 or more, and more preferably 8.75 or more.

The SP value (unit: ((cal / cm ³ ) ^0.5 ) is calculated by the so-called Fedors method described in RF Fedors, Polymer Engineering Science, 14, p147 (1974). In the Fedors method, it is considered that the aggregation energy density and the molar molecular weight depend on the type and number of substituents, and the solubility parameter is expressed by the following formula (1). The solubility parameter is each. It is a value peculiar to the compound.
δ = [ΣEcoh / ΣV] ^0.5 ... (1)
(In the above formula (1), δ indicates the SP value, ΣEcoh indicates the aggregation energy, and ΣV indicates the molar molecular weight.)
The SI unit of the SP value is (J / cm ³ ) ^0.5 or (MPa) ^0.5 , but here, (cal / cm ³ ) ^0.5 , which is conventionally used conventionally, is used. The unit of the SP value can be converted by the following formula: 1 (cal / cm ³ ) ^0.5 ≈ 2.05 (J / cm ³ ) ^0.5 ≈ 2.05 (MPa) ^0.5 ;. ..

The photopolymerizable compound is preferably a photoradical polymerizable compound that polymerizes by irradiation with light, and may be a photopolymerizable monomer or oligomer. One type of photopolymerizable compound may be used alone, or two or more types may be used in combination.

Examples of the photoradical polymerizable compound include a monomer having an ethylenically unsaturated group (hereinafter, also referred to as “ethylenically unsaturated monomer”) and the like. Here, the ethylenically unsaturated monomer means a monomer having an ethylenically unsaturated bond (carbon-carbon double bond). Examples of the ethylenically unsaturated monomer include a monomer having an ethylenically unsaturated group such as a vinyl group, a vinylene group, a vinylidene group, a (meth) acryloyl group, and a (meth) acrylamide group. Monomers having these groups may be referred to as "vinyl monomers".

The ethylenically unsaturated group may be a vinyl group, a vinylene group, a vinylidene group, a (meth) acryloyl group or the like, and is preferably a (meth) acryloyl group. Since the monomer having a (meth) acrylamide group is water-soluble, it easily dissolves nanocrystal particles made of halide metal and significantly deteriorates the light emission characteristics over time. Therefore, it is used in the ink composition of the present invention. Is not preferable. In addition, in this specification, "(meth) acryloyl group" means "acryloyl group" and "methacryloyl group". The same applies to the expression "(meth) acrylate". The "(meth) acryloyl group" means an "acrylamide group" and a "methacrylamide group".

Examples of the photoradical polymerizable compound include a (meth) acrylate compound which is a compound having a (meth) acryloyl group. The (meth) acrylate compound may be a monofunctional (meth) acrylate having one (meth) acryloyl group, or may be a polyfunctional (meth) acrylate having a plurality of (meth) acryloyl groups. Use at least one monofunctional (meth) acrylate from the viewpoint of excellent dispersibility of the luminescent particles when preparing the dispersion, excellent fluidity, and excellent stability of the quantum efficiency of the luminescent particles. Is preferable.

Examples of the monofunctional (meth) acrylate having an SP value of 10.0 or less include a lauryl acrylate (SP value: 8.70, viscosity: 4) and an isostearyl acrylate (SP value: 8.59, viscosity: 17). , Isodecyl acrylate (SP value: 8.39, viscosity: 2.7), n-butyl acrylate (SP value: 8.82, viscosity: 1.1), isobornyl acrylate (SP value: 8.70,) Visolubility: 7.7), cyclohexyl acrylate (SP value: 9.26, viscosity: 2.5), benzyl acrylate (SP value: 9.71, viscosity: 2.2), phenoxyethyl acrylate (SP value: 9.). 74, viscosity: 9), dicyclopentenyl acrylate (SP value: 9.71, viscosity: 8-18), dicyclopentenyloxyethyl acrylate (SP value: 9.65, viscosity: 15-25), dicyclopenta Nyl acrylate (SP value: 9.66, viscosity: 7 to 17), (2-methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate (SP value: 9.21, viscosity: 5. 1), Tetrahydroflufuryl acrylate (SP value: 9.51, viscosity: 2.8), 5-ethyl-1,3-dioxane-5-ylmethyl acrylate (SP value: 9.35, viscosity: 10), 2-ethylhexyl acrylate (SP value: 8.62, viscosity: 1.2), 2- [2- (ethoxy) ethoxy] ethyl acrylate (SP value: 9.08, viscosity: 2.9), methoxytriethylene glycol Acrylate (SP value: 9.18, viscosity: 6), 2-ethylhexyl carbitol acrylate (SP value: 8.82, viscosity: 10), methoxypolyethylene glycol # 400 acrylate (SP value: 9.28, viscosity: 25) ), ), Trt-butyl methacrylate (SP value: 8.48, viscosity: 0.8), 2-ethylhexyl methacrylate (SP value: 8.63, viscosity: 1.7), isodecyl methacrylate (SP value: 8.42). , Visibility: 5.0), Isobornyl methacrylate (SP value: 8.70, viscosity: 11), cyclohexyl methacrylate (SP value: 9.22, viscosity: 2.5), benzyl methacrylate (SP value: 9.). 64, viscosity: 3.5), phenoxyethyl methacrylate Tote (SP value: 9.68, viscosity: 10), dicyclopentenyloxyethyl methacrylate (SP value: 9.60, viscosity: 15 to 20), dicyclopentenyl methacrylate (SP value: 9.60, viscosity) : 7 to 17), etc.
The viscosity is a value at 25 ° C., and the unit is mPa · s (hereinafter, the description of the viscosity is the same unless otherwise specified).

From the viewpoint of further excellent dispersion stability, viscosity stability and quantum efficiency of the luminescent particles, the photopolymerizable compound used for the dispersion has an SP value of 10.0 or less and is photoradical polymerizable having a cyclic structure. It is preferably a compound. The cyclic structure may be an aromatic ring structure or a non-aromatic ring structure. The number of cyclic structures (total number of aromatic rings and non-aromatic rings) is 1 or 2 or more, but preferably 3 or less. The number of carbon atoms constituting the cyclic structure is, for example, 4 or more, and preferably 5 or more or 6 or more. The number of carbon atoms is, for example, 20 or less, preferably 18 or less.

The aromatic ring structure is preferably a structure having an aromatic ring having 6 to 18 carbon atoms. Examples of the aromatic ring having 6 to 18 carbon atoms include a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring and the like. The aromatic ring structure may be a structure having an aromatic heterocycle. Examples of the aromatic heterocycle include a furan ring, a pyrrole ring, a pyran ring, a pyridine ring and the like. The number of aromatic rings may be 1 or 2 or more, but is preferably 3 or less. The organic group may have a structure (for example, a biphenyl structure) in which two or more aromatic rings are bonded by a single bond.

The non-aromatic ring structure is preferably a structure having, for example, an alicyclic having 5 to 20 carbon atoms. Examples of the alicyclic ring having 5 to 20 carbon atoms include a cycloalkane ring such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring, a cycloalkene ring such as a cyclopentene ring, a cyclohexene ring, a cycloheptene ring, and a cyclooctene ring. Can be mentioned. The alicyclic ring may be a fused ring such as a bicycloundecane ring, a decahydronaphthalene ring, a norbornene ring, a norbornadiene ring, or an isobornyl ring. The non-aromatic ring structure may be a structure having a non-aromatic heterocycle. Examples of the non-aromatic heterocycle include a tetrahydrofuran ring, a pyrrolidine ring, a tetrahydropyran ring, a piperidine ring and the like.

The photoradical polymerizable compound having an SP value of 10.0 or less and having a cyclic structure is preferably a monofunctional photoradical polymerizable compound having a cyclic structure and is a monofunctional (meth) acrylate compound. Examples of the monofunctional (meth) acrylate compound having an SP value of 10.0 or less and having a cyclic structure include isobornyl acrylate (SP value: 8.70, viscosity: 7.7) and cyclohexyl acrylate (SP). Value: 9.26, viscosity: 2.5), benzyl acrylate (SP value: 9.71, viscosity: 2.2), phenoxyethyl acrylate (SP value: 9.74, viscosity: 9), dicyclopentenyl acrylate (SP value: 9.71, viscosity: 8-18), dicyclopentenyloxyethyl acrylate (SP value: 9.65, viscosity: 15-25), dicyclopentanyl acrylate (SP value: 9.66, viscosity) : 7-17), (2-Methyl-2-ethyl-1,3-dioxolan-4-yl) methyl acrylate (SP value: 9.21, viscosity: 5.1), tetrahydrofurfuryl acrylate (SP value: 9.51, viscosity: 2.8), 5-ethyl-1,3-dioxane-5-ylmethylacrylate (SP value: 9.35, viscosity: 10), isobornyl methacrylate (SP value: 8.70) , Viscosity: 11), Cyclohexyl methacrylate (9.22, 2.5), benzyl methacrylate (SP value: 9.64, viscosity: 3.5), phenoxyethyl methacrylate (SP value: 9.68, viscosity: 10) , Dicyclopentenyloxyethyl methacrylate (SP value: 9.60, viscosity: 15 to 20), dicyclopentanyl methacrylate (SP value: 9.60, viscosity: 7 to 17) and the like.

As the dispersion used as the inkjet ink, a monofunctional photopolymerizable compound having a cyclic structure having a viscosity at 25 ° C. of 20 mPa · s or less is preferable from the viewpoint of lowering the viscosity of the dispersion. Specific examples of the photopolymerizable compound include phenoxyethyl acrylate, benzyl acrylate, isobornyl acrylate, tetrahydrofurfuryl acrylate, dicyclopentenyloxyethyl acrylate, 5-ethyl-1,3-dioxane-5. -Ilmethyl acrylate, phenoxyethyl methacrylate, benzyl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, dicyclopentenyloxyethyl methacrylate are preferable, and phenoxyethyl acrylate, isobornyl acrylate, 5-ethyl-1,3-dioxane- Examples thereof include 5-ylmethyl acrylate, phenoxyethyl methacrylate and isobornyl methacrylate.

The content of the monofunctional photopolymerizable compound having a cyclic structure is the total mass of the photopolymerizable compound in the dispersion from the viewpoint of obtaining excellent dispersion stability, viscosity stability and quantum efficiency of the dispersion. As a reference, it is preferably 50 to 95% by mass, more preferably 65 to 90% by mass, and particularly preferably 80 to 85% by mass.

In the dispersion, in addition to the monofunctional photopolymerizable compound as described above, the durability (strength, heat resistance, etc.) of the cured product can be further enhanced within a range that does not deteriorate the quantum yield of the luminescent particles. , A bifunctional or higher polyfunctional photopolymerizable compound having two or more polymerizable functional groups in one molecule may be used.
The polyfunctional photopolymerizable compound is a polyfunctional (meth) acrylate. Examples of the polyfunctional (meth) acrylate include bifunctional (meth) acrylate, trifunctional (meth) acrylate, tetrafunctional (meth) acrylate, pentafunctional (meth) acrylate, and hexafunctional (meth) acrylate.

Specific examples of the bifunctional (meth) acrylate include 1,3-butylene glycol diacrylate (molecular weight: 226, viscosity: 9 mPa · s) and 1,4-butanediol diacrylate (molecular weight: 198, viscosity: 8 mPa · s). -S), 3-Methyl-1,5-pentanediol diacrylate (molecular weight: 226, viscosity: 8 mPa · s), 1,6-hexanediol diacrylate (molecular weight: 226, viscosity: 7 mPa · s), neopentyl Glycol diacrylate (molecular weight: 212, viscosity: 6 mPa · s), 1,9-nonanediol diacrylate (molecular weight: 268, viscosity: 8 mPa · s), tricyclodecanedimethanol diacrylate (molecular weight: 304, viscosity: 130 mPa) · S), Polyethylene Glycol # 200 Diacrylate (Molecular Weight: 302, Viscosity: 12 mPa · s), Polyethylene Glycol # 300 Diacrylate (Molecular Weight: 408, Viscosity: 50 mPa · s), Polyethylene Glycol # 400 Diacrylate (Molecular Weight: 548) , Viscosity: 50 mPa · s), Dipropylene glycol diacrylate (Molecular weight: 242, Viscosity: 10 mPa · s) Tripropylene glycol diacrylate (Molecular weight: 300, Viscosity: 13 mPa · s) Polypropylene glycol # 400 diacrylate (Molecular weight: 533) , Viscosity: 35 mPa · s) 1,3-butylene glycol dimethacrylate (molecular weight: 226, viscosity: 5 mPa · s), 1,4-butanediol dimethacrylate (molecular weight: 226, viscosity: 7 mPa · s), 1,6 -Hexanediol dimethacrylate (molecular weight: 254, viscosity: 6 mPa · s), neopentyl glycol dimethacrylate (molecular weight: 240, viscosity: 5 mPa · s), 1,9-nonanediol dimethacrylate (molecular weight: 296, viscosity: 8 mPa) S), tricyclodecanedimethanol dimethacrylate (molecular weight: 332, viscosity: 110 mPa · s), ethylene glycol dimethacrylate (molecular weight: 198, viscosity: 4 mPa · s), triethylene glycol dimethacrylate (molecular weight: 286, viscosity) : 9 mPa · s), polyethylene glycol # 200 dimethacrylate (molecular weight: 330, viscosity: 14 mPa · s), polyethylene glycol # 400 dimethacrylate (molecular weight: 550, viscosity: 35 mPa · s) and the like.

Specific examples of the trifunctional (meth) acrylate include trimethylolpropane triacrylate (molecular weight 286 :, viscosity: 100 mPa · s), glycerin triacrylate (molecular weight 254 :, viscosity: 30 mPa · s), and pentaerythritol triacrylate. (Molecular weight 298 :, Molecular weight: 1800 mPa · s) Triacrylate in which three hydroxyl groups of triol obtained by adding 3 mol of ethylene oxide to 1 mol of trimethylolpropane is substituted with an acryloyloxy group (molecular weight: 428, Viscosity: 65 mPa · s) Triacrylate (molecular weight: 470, viscosity: 110 mPa · s) in which the three hydroxyl groups of triol obtained by adding 3 mol of propylene oxide to 1 mol of trimethylolpropane are substituted with acryloyloxy groups. ), Trimethylolpropane trimethacrylate (molecular weight: 338, viscosity: 60 mPa · s) and the like.

Specific examples of the tetrafunctional (meth) acrylate include pentaerythritol tetraacrylate (molecular weight: 352, viscosity: 342 mPa · s), ditrimethylolpropane tetraacrylate (molecular weight: 467, viscosity: 750 mPa · s) and the like. ..

Specific examples of the pentafunctional (meth) acrylate include dipentaerythritol pentaacrylate (molecular weight: 524, viscosity: 13600 mPa · s) and the like.

Specific examples of the hexafunctional (meth) acrylate include dipentaerythritol hexaacrylate (molecular weight: 578, viscosity: 7000 mPa · s) and the like.

Further, the dispersion uses a bifunctional or higher polyfunctional photopolymerizable compound in combination with a monofunctional photopolymerizable compound from the viewpoint of obtaining a viscosity suitable for inkjet printing and obtaining good curability. May be good. In this case, the photopolymerizable compound contained in the dispersion preferably contains a monofunctional (meth) acrylate and a polyfunctional (meth) acrylate.

From the viewpoint of obtaining the above effects, the polyfunctional photopolymerizable compound is preferably 5 to 35% by mass, more preferably 10 to 30% by mass, and 15 to 25% by mass with respect to the total amount of the dispersion. It is particularly preferable to be% by mass.

Further, from the viewpoint of obtaining a viscosity suitable for inkjet printing, obtaining excellent curability of a coating film, and obtaining excellent quantum efficiency of an optical conversion layer, the dispersion used in the ink composition is polyfunctional. The molecular weight of the photopolymerizable compound is, for example, 50 or more, and may be 100 or more or 150 or more. The molecular weight of the photopolymerizable compound is, for example, 500 or less, and may be 400 or less or 300 or less. From the viewpoint of easily achieving both the viscosity of the inkjet ink and the volatility of the ink after ejection, it is preferably 50 to 500, and more preferably 100 to 400.

The content of the photopolymerizable compound having a cyclic structure is from the viewpoint that it is easy to suppress the stickiness (tack) of the surface of the coating film, it is easy to obtain an appropriate viscosity as an inkjet ink, and it is easy to obtain excellent ejection properties. Based on the total mass of the photopolymerizable compound in the dispersion, it is preferably 3 to 85% by mass, more preferably 5 to 65% by mass, further preferably 10 to 45% by mass, and 15 It is particularly preferable that the content is ~ 35% by mass.

<< Block Copolymer >>
The block copolymer comprises a first structural unit having a basic group and a second structural unit having an affinity for the photopolymerizable compound. In such a block copolymer, the basic group of the first structural unit is easily adsorbed on the surface of the luminescent particles (hollow silica particles), and the second structural unit is relative to the photopolymerizable compound. Has affinity. Therefore, the dispersion of the present embodiment contains the block copolymer, so that the block copolymer acts as a dispersant, and the surface is hollow silica, so that luminescent particles having a highly polar surface can be obtained. It can be well dispersed in the above-mentioned photopolymerizable compounds having low polarity.

Specifically, the block copolymer has a polymer block (A) composed of a monomer having a basic group and a polymer block (B) composed of a prosolvent monomer. The one is preferable. The term "parent solvent" as used herein means an affinity for a photopolymerizable compound (the same applies hereinafter). When having such a structure, the polymer block (A) having a basic group which is an adsorption portion with the luminescent particles is arranged in one mass, and the co-solvent polymer block (B) (for example, light) is arranged. Since the portion that is difficult to be adsorbed on the luminescent particles while improving the affinity with the polymerizable compound) is arranged as another mass, it is easier to adsorb to the luminescent particles as compared with the random copolymer. It will be something like that.

Here, the structural unit constituting each block may be one type or two or more types. Further, the block copolymer may further include a structural unit having an acidic group.

Examples of the basic group include an amino group, an ammonium group, an imino group, and a nitrogen-containing heterocyclic group. The amino group may be a primary, secondary or tertiary amino group. Examples of the primary, secondary or tertiary amino group include a methylamino group, an ethylamino group, a tert-butylamino group, a dimethylamino group, a diethylamino group, a di-tert-butylamino group and the like. The amino group may be an amino group bonded to an aromatic ring. Examples of the amino group bonded to the aromatic ring include aniline, anisidin, p-toluidine, α-naphthylamine, m-phenylenediamine, 1,8-diaminonaphthalene, benzylamine, N-methylaniline and N-methylbenzylamine. It may be derived from the above. Examples of the nitrogen-containing heterocyclic group include a pyridine group, a pyrimidine group, a pyrazine group, an imidazole group, and a triazole group.

Examples of the monomer having a basic group include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) crylate, diethylaminoethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 4-vinylaniline, 1-. Examples thereof include vinyl imidazole and allylamine.

The solvent-friendly monomer is an ethylenically unsaturated monomer, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-. Butyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, Alkyl (meth) acrylates such as pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecil (meth) acrylate, and icosanyl (meth) acrylate; benzyl (meth) acrylate, phenyl. (Meta) acrylate having an alicyclic structure such as aromatic (meth) acrylate such as ethyl (meth) acrylate, cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol ( Meta) Acrylate, Octoxy Polyethylene Glycol (Meta) Acrylate, Octoxy Polypropylene Glycol (Meta) Acrylate, Lauroxy Polypropylene Glycol (Meta) Acrylate, Lauroxy Polypropylene Glycol (Meta) Acrylate, Stearoxy Polyethylene Glycol, Stearoxy Polypropylene Glycol ( Alkyl group-terminated polyalkylene glycol (meth) such as meta) acrylate, allyloxypolyethylene glycol (meth) acrylate, allyloxypolypolyglycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, and nonylphenoxypolypolyglycol glycol (meth) acrylate. Acrylate; (meth) acrylate compounds such as glycidyl (meth) acrylate, dicyclopentenyl (meth) acrylate, tricyclodecanyl (meth) acrylate; styrene, α-methylstyrene, 4-tert-butylstyrene, 2,5- Examples thereof include styrene derivative monomers such as dimethylstyrene and p-isobutylstyrene.

The content of the first structural unit in the block copolymer may be, for example, 5 mol% or more, 7 mol% or more, or 10 mol% or more based on all the structural units constituting the block copolymer. It is preferably 50 mol% or less, 30 mol% or less, or 20 mol% or less.

The content of the second structural unit in the block copolymer may be, for example, 70 mol% or more, 75 mol% or more, or 80 mol% or more based on all the structural units constituting the block copolymer. It is preferably 95 mol% or less, 93 mol% or less, or 90 mol% or less.

The block copolymer may contain other structural units in addition to the first structural unit and the second structural unit. In that case, the total content of the first structural unit and the second structural unit in the block copolymer is, for example, 70 mol% or more and 80 mol% based on all the structural units constituting the block copolymer. It is preferably 90 mol% or more, or 90 mol% or more.

For example, the block copolymer may have a structural unit having an acidic group, a nonionic functional group, or the like, in addition to the first structural unit and the second structural unit.

The acidic group includes a carboxyl group (-COOH), a sulfo group (-SO ₃ H), a sulfate group (-OSO ₃ H), a phosphonic acid group (-PO (OH) ₃ ), and a phosphoric acid group (-OPO (OH)). ) ₃ ), phosphinic acid group (-PO (OH)-), mercapto group (-SH), and the like.

Nonionic functional groups include hydroxy group, ether group, thioether group, sulfinyl group (-SO-), sulfonyl group ( _-SO2- ), carbonyl group, formyl group, ester group, carbonate ester group, amide group, and the like. Examples thereof include a carbamoyl group, a ureido group, a thioamide group, a thioureido group, a sulfamoyl group, a cyano group, an alkenyl group, an alkynyl group, a phosphin oxide group and a phosphin sulfide group.

Examples of the monomer having an acidic group include (meth) acrylate having a carboxy group, (meth) acrylate having a phosphoric acid group, and (meth) acrylate having a sulfone group. Examples of the (meth) acrylate having a carboxy group include carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, 2- (meth) acryloyloxyethyl succinate, 2- (meth) acryloyloxyethyl maleate, and 2-. Examples thereof include a monomer obtained by reacting a (meth) acrylate having a hydroxy group such as (meth) acryloyloxyethyl phthalate with an acid anhydride such as maleic anhydride, succinic anhydride and phthalic anhydride, and (meth) acrylic acid. Examples of the (meth) acrylate having a sulfonic acid group include ethyl sulfonate (meth) acrylate. Examples of the (meth) acrylate having a phosphoric acid group include 2- (phosphonooxy) ethyl (meth) acrylate.

Examples of the block copolymer having a structural unit having a basic group and a pro-solvent structural unit include an acrylic block copolymer, a polyester block copolymer, a polyurethane block copolymer, and a polyether block copolymer. Examples thereof include block copolymers, polyethyleneimine-based block copolymers and polyallylamine-based block copolymers.

The block copolymer preferably has an amine value of more than 0 mgKOH / g, more preferably, from the viewpoint of further improving the adsorptivity to hollow silica particles including luminescent particles and obtaining further excellent dispersibility. It is 2 mgKOH / g or more, more preferably 4 mgKOH / g or more, particularly preferably 10 mgKOH / g or more, and most preferably 20 mgKOH / g or more. The block copolymer has an amine value of 70 mgKOH / g or less, more preferably 60 mgKOH / g, from the viewpoint of excellent solubility in a photopolymerizable compound and less likely to cause particle aggregation and deterioration of storage stability. It is g or less, more preferably 50 mgKOH / g or less, and particularly preferably 40 mgKOH / g or less.

The amine value of the block copolymer can be measured as follows.
Prepare a sample solution prepared by dissolving 1 mL of block copolymer xg and bromophenol blue test solution in 50 mL of a mixed solution of toluene and ethanol mixed at a volume ratio of 1: 1 and prepare the sample solution with 0.5 mol / L hydrochloric acid. Titration is performed until it turns green, and the amine value can be calculated by the following formula.
Amine value = y / x × 28.05
In the formula, y indicates the titration amount (mL) of 0.5 mol / L hydrochloric acid required for titration, and x indicates the mass (g) of the block copolymer.

When the block copolymer has an acidic group, the acid value of the block copolymer is preferably 0 to 50 mgKOH / g, more preferably 0 to 40 mgKOH / g, and 0 to 30 mgKOH / g. It is more preferably 0 to 20 mgKOH / g or less, and particularly preferably 0 to 20 mgKOH / g or less. The acid value of the block copolymer is preferably 50 mgKOH / g or less because the storage stability of the pixel portion (cured product of the ink composition) is unlikely to decrease.

The acid value of the block copolymer can be measured as follows.
A sample solution prepared by dissolving 1 mL of block copolymer pg and phenol phthalein test solution in 50 mL of a mixed solution of toluene and ethanol mixed at a volume ratio of 1: 1 was prepared, and a 0.1 mol / L ethanol potassium hydroxide solution was prepared. (Prepared to 1000 mL by dissolving 7.0 g of potassium hydroxide in 5.0 mL of distilled water and adding 95 vol% ethanol) was titrated until the sample solution turned pink, and the acid value was determined by the following formula. Can be calculated.
Acid value = q × r × 5.611 / p
In the formula, q indicates the titration amount (mL) of the 0.1 mol / L ethanol potassium hydroxide solution required for titration, and r indicates the titer of the 0.1 mol / L ethanol potassium hydroxide solution required for titration. Shown, p indicates the mass (g) of the block copolymer.

Such a block copolymer can be used, for example, by obtaining a commercially available product. For example, examples of the block copolymer having a tertiary amino group or a nitrogen-containing heterocycle include, for example, "DISPERBYK (registered trademark) -164" (amine value: 18 mgKOH / g) and "DISPERBYK-167". (Amine value: 13 mgKOH / g), "DISPERBYK-2000" (amine value: 4 mgKOH / g), "DISPERBYK-2008" (amine value: 66 mgKOH / g), "DISPERBYK-2009" (amine value: 4 mgKOH / g) , "DISPERBYK-2164" (amine value: 23 mgKOH / g) (above, manufactured by Big Chemie Japan Co., Ltd.), "Solspers (registered trademark) 20000" (amine value: 32 mgKOH / g) (manufactured by Japan Lubrizol), " EFKA (registered trademark) PX4300 "(amine value: 56 mgKOH / g)," EFKA PX4310 "(amine value: 19 mgKOH / g)," EFKA PX4320 "(amine value: 28 mgKOH / g)," EFKA PX4330 "(amine value:: 28 mgKOH / g), "EFKA PX4340" (amine value: 4 mgKOH / g), "EFKA PX4350" (amine value: 12 mgKOH / g), "Dispex (registered trademark) Ultra PX4585" (amine value: 20 mgKOH / g), " Examples thereof include "EFKA PX4700" (amine value: 60 mgKOH / g), "EFKA PX4701 (amine value: 40 mgKOH / g)", "EFKA PX4703 (amine value: 56 mgKOH / g)" (manufactured by BASF Japan Co., Ltd.).

Further, for example, as the block copolymer having an amine value and an acid value, for example, "DISPERBYK-180" (amine value: 95 mgKOH / g, acid value: 95 mgKOH / g), "DISPERBYK-2001" (amine value:: 29 mgKOH / g, acid value: 19 mgKOH / g), "DISPERBYK-2025" (amine value: 37 mgKOH / g, acid value: 38 mgKOH / g) (above, manufactured by Big Chemie Japan Co., Ltd.) "Ajispar (registered trademark) PB821" (Amin value: 10 mgKOH / g, acid value: 17 mgKOH / g), "Ajisper PB822" (amine value: 17 mgKOH / g, acid value: 14 mgKOH / g), "Ajisper PB824" (amine value: 17 mgKOH / g, acid value) : 21 mgKOH / g), "Ajisper PB881" (amine value: 17 mgKOH / g, acid value: 17 mgKOH / g) (all manufactured by Ajinomoto Fine Techno Co., Ltd.) and the like.

From the viewpoint of further improving the dispersibility, the content of the block copolymer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, still more preferably 5 parts by mass or more with respect to 100 parts by mass of the luminescent particles. Particularly preferably, it is 7 parts by mass or more. The content of the block copolymer is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and further, with respect to 100 parts by mass of the luminescent particles, from the viewpoint of suppressing a decrease in the quantum yield of the luminescent particles. It is preferably 16 parts by mass or less, and particularly preferably 14 parts by mass or less.

The content of the block copolymer is preferably 0.1% by mass or more, more preferably 0.15% by mass or more, still more preferably 0.% by mass, based on the total amount of the dispersion, from the viewpoint of further improving the dispersibility. It is 2% by mass or more, particularly preferably 0.25% by mass or more. The content of the block copolymer is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, based on the total amount of the dispersion, from the viewpoint of suppressing a decrease in the quantum yield of the luminescent particles. It is more preferably 0.8% by mass or less, and particularly preferably 0.7% by mass or less.

The above dispersion can be prepared by dispersing luminescent particles in a solution in which a block copolymer and a photopolymerizable compound are mixed. Dispersion of luminescent particles can be performed by using, for example, a ball mill, a sand mill, a bead mill, a three-roll mill, a paint conditioner, an attritor, a dispersion stirrer, a disperser such as an ultrasonic wave.

The dispersion as described above can be prepared by mixing luminescent particles in a solution containing a block copolymer, a photopolymerizable compound, or the like. The dispersion can be prepared, for example, by using a ball mill, a sand mill, a bead mill, a paint conditioner, an attritor, a dispersion stirrer, a disperser such as an ultrasonic wave, or the like.

<< Ink composition >>
The dispersion of the present invention can further contain a photopolymerizable compound and a photopolymerizable initiator. Dispersions containing these are suitable as ink compositions, particularly ink composition for inkjet. Hereinafter, the dispersion containing the photopolymerizable compound and the photopolymerizable initiator may be referred to as an “ink composition”.

<< Photopolymerization Initiator >>
The photopolymerization initiator used in the ink composition is preferably at least one selected from the group consisting of alkylphenone-based compounds, acylphosphine oxide-based compounds and oxime ester-based compounds.

Examples of the alkylphenone-based photopolymerization initiator include compounds represented by the formula (b-1).

(In the formula, R1a represents a group selected from the following formulas (R ^1a -1) to (R ^1a -6), and R ^2a , R ^2b and R ^2c independently represent the following formula (R ² ). -1) -Represents a group selected from the formula (R ^2-7 ).)

As a specific example of the compound represented by the above formula (b-1), the compounds represented by the following formulas (b-1-1) to (b-1-6) are preferable, and the following formula (b-1) is preferable. -1), the compound represented by the formula (b-1-5) or the formula (b-1-6) is more preferable.

Examples of the acylphosphine oxide-based photopolymerization initiator include compounds represented by the formula (b-2).

(In the formula, R ²⁴ represents an alkyl group, an aryl group or a heterocyclic group, and R ²⁵ and R ²⁶ each independently represent an alkyl group, an aryl group, a heterocyclic group or an alkanoyl group. May be substituted with an alkyl group, a hydroxyl group, a carboxyl group, a sulfon group, an aryl group, an alkoxy group, or an arylthio group.)

As specific examples of the compound represented by the above formula (b-2), the compounds represented by the following formulas (b-2-1) to (b-2-5) are preferable, and the following formula (b-2) is preferable. A compound represented by -1) or the formula (b-2-5) is more preferable.

Examples of the oxime ester-based photopolymerization initiator include compounds represented by the following formula (b-3-1) or formula (b-3-2).

(In the formula, R ²⁷ to R ³¹ each independently represent a hydrogen atom, a cyclic, linear or branched alkyl group having 1 to 12 carbon atoms, or a phenyl group, and each alkyl group and phenyl group. May be substituted with a substituent selected from the group consisting of a halogen atom, an alkoxyl group having ¹ to ⁶ carbon atoms and a phenyl group, where X1 represents an oxygen atom or a nitrogen atom and X2 is oxygen. It represents an atom or NR, and R represents an alkyl group having 1 to 6 carbon atoms.)

Specific examples of the compounds represented by the above formulas (b-3-1) and (b-3-2) include the following formulas (b-3-1-1) to (b-3-1-2). ) And the compounds represented by the following formulas (b-3-2-1) to (b-3--2-2) are preferable, and the following formulas (b-3-1-1) and (b-3-2) are preferable. A compound represented by -1) or the formula (b-3-2-2) is more preferable.

The content of the photopolymerization initiator is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, still more preferably 1% by mass or more, based on the total amount of the photopolymerizable compounds contained in the dispersion. It is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 6% by mass or less. The photopolymerization initiator may be used alone or in combination of two or more. The dispersion containing the photopolymerization initiator in such an amount sufficiently maintains the photosensitivity at the time of photocuring, and the crystals of the photopolymerization initiator are less likely to precipitate when the coating film is dried, thereby suppressing deterioration of the physical properties of the coating film. can do.

When dissolving the photopolymerization initiator in the dispersion, it is preferable to dissolve it in the photopolymerizable compound in advance before use.
In order to dissolve the photopolymerizable compound, it is preferable to uniformly dissolve the photopolymerizable compound by adding a photopolymerization initiator while stirring so that the reaction due to heat is not started.
The dissolution temperature of the photopolymerization initiator may be appropriately adjusted in consideration of the solubility of the photopolymerization initiator used in the photopolymerizable compound and the thermal polymerizable property of the photopolymerizable compound, but the polymerization of the photopolymerizable compound may be appropriately adjusted. The temperature is preferably 10 to 50 ° C., more preferably 10 to 40 ° C., and even more preferably 10 to 30 ° C. from the viewpoint of not starting the polymerization.

<< Light-scattering particles >>
The ink composition may further contain light scattering particles. The light-scattering particles are preferably, for example, optically inactive inorganic fine particles. The light-scattering particles can scatter the light from the light source portion irradiated to the light emitting layer (light conversion layer).

Materials that make up the light-scattering particles include, for example, single metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, platinum, and gold; silica, barium sulfate, barium carbonate, calcium carbonate. Metal oxides such as talc, titanium oxide, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, alumina white, titanium oxide, magnesium oxide, barium oxide, aluminum oxide, bismuth oxide, zirconium oxide, zinc oxide; Metal carbonates such as magnesium, barium carbonate, bismuth hypocarbonate, calcium carbonate; metal hydroxides such as aluminum hydroxide; barium zirconate, calcium zirconate, calcium titanate, barium titanate, strontium titanate, etc. Examples thereof include composite oxides and metal salts such as bismuth subnitrate.
Among them, as a material constituting the light-scattering particles, at least one selected from the group consisting of titanium oxide, alumina, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate and silica from the viewpoint of being more excellent in the effect of reducing leakage light. It preferably contains seeds, more preferably contains at least one selected from the group consisting of titanium oxide, barium sulfate and calcium carbonate, and particularly preferably titanium oxide.

When titanium oxide is used, it is preferably surface-treated titanium oxide from the viewpoint of dispersibility. There is a known method as a surface treatment method for titanium oxide, but it is more preferable that the surface treatment contains at least alumina.

Titanium oxide that has been surface-treated to contain alumina means a treatment that precipitates at least alumina on the surface of titanium oxide particles, and silica or the like can be used in addition to alumina. Alumina or silica also contains their hydrates.

In this way, the surface of the titanium oxide particles is uniformly surface-coated by performing a surface treatment containing alumina on the titanium oxide particles, and at least when the titanium oxide particles surface-treated with alumina are used, the titanium oxide particles are dispersed. The sex becomes good.

Further, when the treatment with silica and the treatment with alumina are applied to the titanium oxide particles, the alumina and silica treatment may be performed at the same time, and in particular, the alumina treatment may be performed first, and then the silica treatment may be performed. When the treatments of alumina and silica are performed, the amount of alumina and silica to be treated is preferably more silica than that of alumina.

The surface treatment of titanium oxide with a metal oxide such as alumina or silica can be performed by a wet method. For example, titanium oxide particles surface-treated with alumina or silica can be produced as follows.

Titanium oxide particles (number average primary particle diameter: 200 to 400 nm) are dispersed in water at a concentration of 50 to 350 g / L to form an aqueous slurry, to which a water-soluble silicate or a water-soluble aluminum compound is added. Then, an alkali or an acid is added to neutralize the particles, and silica or alumina is deposited on the surface of the titanium oxide particles. Subsequently, it is filtered, washed and dried to obtain the desired surface-treated titanium oxide. When sodium silicate is used as the water-soluble silicate, it can be neutralized with an acid such as sulfuric acid, nitric acid, or hydrochloric acid. On the other hand, when aluminum sulfate is used as the water-soluble aluminum compound, it can be neutralized with an alkali such as sodium hydroxide or potassium hydroxide.

The content of the light-scattering particles may be 0.5% by mass or more, 1% by mass or more, or 2% by mass or more, based on the total mass of the ink composition, and may be 10% by mass or less, 9% by mass or less, or. It may be 8% by mass or less.

The ink composition may contain components other than the dispersion, the photopolymerizable compound, the photopolymerization initiator, and the light-scattering particles as long as the effects of the present invention are not impaired. Examples of such other components include polymer dispersants, polymerization inhibitors, antioxidants, leveling agents, chain transfer agents, thermoplastic resins, sensitizers and the like.

<< Polymer Dispersant >>
In the ink composition, the above-mentioned block copolymer may be used as the polymer dispersant for improving the dispersion stability of the light-scattering particles, or other dispersants may be used. Here, dispersants other than the above-mentioned block copolymers will be described.

The polymer dispersant is a molecule having a weight average molecular weight (Mw) of more than 5,000. As the "weight average molecular weight (Mw)", a value measured by gel permeation chromatography (GPC) using polystyrene as a standard material can be adopted.

Examples of the polymer dispersant include acrylic resins, polyester resins, polyurethane resins, polyamide resins, polyether resins, phenol resins, silicone resins, polyurea resins, amino resins, and polyamine resins ( Polyethylene imine, polyallylamine, etc.), epoxy resins, polyimide resins, wood rosins, gum rosins, natural rosins such as tall oil rosins, polymerized rosins, disproportionated rosins, hydrogenated rosins, oxide rosins, maleated rosins, etc. Examples thereof include modified rosin, rosinamine, lime rosin, rosin alkylene oxide adduct, rosin alkyd adduct, rosin derivatives such as rosin-modified phenol, and the like.

Commercially available polymer dispersants include, for example, DISPERBYK series manufactured by Big Chemie, TEGO (registered trademark) Dispers series manufactured by Ebonic, EFKA series manufactured by BASF, and SOLSPERSE (registered trademark) manufactured by Japan Lubrizol. ) Series, Ajinomoto Fine-Techno's Ajispar series, Kusumoto Kasei's DISPARLON (registered trademark) series, Kyoeisha Chemical Co., Ltd.'s Floren series, etc. (excluding those corresponding to the above-mentioned block copolymers) can do.

<< Polymerization inhibitor >>
Examples of the polymerization inhibitor include phenol-based compounds, quinone-based compounds, amine-based compounds, thioether-based compounds, N-oxyl compounds, nitroso-based compounds and the like.
The amount of the polymerization inhibitor added is preferably 0.01 to 1.0% by mass, more preferably 0.02 to 0.5% by mass, based on the total amount of the ink composition.

<< Antioxidant >>
Examples of the antioxidant include pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate (“IRGANOX® 1010”)) and thiodiethylenebis [3- (3). , 5-Di-tert-butyl-4-hydroxyphenyl) propionate ("IRGANOX1035"), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ("IRGANOX1076"), "IRGANOX1135" , "IRGANOX1330", 4,6-bis (octylthiomethyl) -o-cresol ("IRGANOX1520L"), "IRGANOX1726", "IRGANOX245", "IRGANOX259", "IRGANOX3114", "IRGANOX3790", "IRGANOX5057", "IRGANOX565" (above, manufactured by BASF Co., Ltd.); "Adecastab (registered trademark) AO-20", "Adecastab AO-30", "Adecastab AO-40", "Adecastab AO-50", "Adecastab AO-60" , "Adecastab AO-80" (above, manufactured by ADEKA Co., Ltd.); "JP-360", "JP-308E", "JPE-10" (above, manufactured by Johoku Chemical Industry Co., Ltd.); "Smilizer (registered trademark)" Examples thereof include "BHT", "Smilizer BBM-S", and "Smilizer GA-80" (all manufactured by Sumitomo Chemical Co., Ltd.).
The amount of the antioxidant added is preferably 0.01 to 2.0% by mass, more preferably 0.02 to 1.0% by mass, based on the total amount of the ink composition.

<< Leveling agent >>
The leveling agent is not particularly limited, but a compound capable of reducing film thickness unevenness when forming a thin film of luminescent particles is preferable.
Examples of such leveling agents include alkyl carboxylates, alkyl phosphates, alkyl sulfonates, fluoroalkyl carboxylates, fluoroalkyl phosphates, fluoroalkyl sulfonates, polyoxyethylene derivatives, and fluoroalkyl ethylene oxide derivatives. , Polyethylene glycol derivatives, alkylammonium salts, fluoroalkylammonium salts, silicone polymers, fluoropolymers and the like.

The content of the leveling agent is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, preferably 2% by mass or less, and more preferably 0.5 with respect to the total amount of the ink composition. It is less than mass%.

<< Chain Transfer Agent >>
The chain transfer agent is a component used for the purpose of further improving the adhesion of the dispersion to the substrate.

Examples of the chain transfer agent include aromatic hydrocarbons, halogenated hydrocarbons, mercaptan compounds, thiol compounds, sulfide compounds and the like.

The amount of the chain transfer agent added is preferably 0.1 to 10% by mass, more preferably 1.0 to 5% by mass, based on the total amount of the ink composition.

<< Thermoplastic resin >>
Examples of the thermoplastic resin include urethane resin, acrylic resin, polyamide resin, polyimide resin, styrene maleic acid resin, styrene anhydride maleic acid resin, polyester acrylate resin and the like.

<< Sensitizer >>
As the sensitizer, a thioxanthone-based compound, a benzophenone-based compound, a quinone-based compound, amines and the like can be used. Examples of such sensitizers include 2-isopropylthioxanthone, 2,4-diethylthioxanthone, benzophenone, 4,4'-bis (diethylamino) benzophenone, 2-ethylanthraquinone, trimethylamine, methyldimethanolamine, and triethanolamine. , P-Diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate and the like.

<< Viscosity of ink composition >>
The viscosity of the ink composition at 30 ° C. is preferably in the range of 2 to 20 mPa · s, more preferably in the range of 5 to 15 mPa · s, and 7 to 7 to 7 to s, from the viewpoint of ejection stability during inkjet printing. It is more preferably in the range of 12 mPa · s. In this case, since the meniscus shape of the dispersion in the ink ejection hole of the ejection head is stable, the ejection control of the dispersion (for example, the control of the ejection amount and the ejection timing) becomes easy. In addition, the ink composition can be smoothly ejected from the ink ejection holes. The viscosity of the ink composition can be measured by, for example, an E-type viscometer.

The viscosity increase rate of the ink composition may be 5% or less, 1% or less, or 0.5% or less, and may be 0.01% or more. The viscosity increase rate of the ink composition is a value calculated by the following formula.
Equation: (η ₁ -η ₀ ) / η ₀ × 100
Here, η ₁ indicates the viscosity of the ink composition after storage at 40 ° C. for 1 week at 30 ° C., and η ₀ indicates the viscosity of the ink composition of the ink composition before storage.

<< Surface tension of ink composition >>
The surface tension of the ink composition at 30 ° C. is preferably a surface tension suitable for the inkjet printing method. The specific value of the surface tension is preferably in the range of 20 to 40 mN / m, and more preferably in the range of 25 to 35 mN / m. By setting the surface tension in the above range, it is possible to suppress the occurrence of flight bending of the droplets of the dispersion. The flight bending means that when the dispersion is ejected from the ink ejection holes, the landing position of the dispersion deviates by 30 μm or more from the target position.

The ink composition as described above can be prepared by mixing the above-mentioned dispersion in a solution in which a photopolymerizable compound, a photopolymerization initiator, a light scattering particle and the like are mixed. The ink composition can be adjusted by using, for example, a ball mill, a sand mill, a bead mill, a three-roll mill, a paint conditioner, an attritor, a dispersion stirrer, a disperser such as an ultrasonic wave, and a propeller mixer.

<Dispersion set>
Another embodiment of the invention is a dispersion set. The dispersion set of one embodiment comprises the dispersion of the above-described embodiment. The dispersion set may include a dispersion (non-luminescent dispersion) containing no luminescent particles in addition to the dispersion (luminescent dispersion) of the above-described embodiment. The non-luminescent dispersion is, for example, a curable dispersion. The non-luminescent dispersion may be a conventionally known dispersion, and may have the same composition as the dispersion (luminescent dispersion) of the above-described embodiment except that it does not contain luminescent particles.

Since the non-luminescent dispersion does not contain luminescent particles, the pixel portion when light is incident on the pixel portion formed by the non-luminescent dispersion (the pixel portion containing the cured product of the non-luminescent dispersion). The light emitted from the light has substantially the same wavelength as the incident light. Therefore, the non-emissive dispersion is suitably used for forming a pixel portion having the same color as the light from the light source. For example, when the light from the light source is light having a wavelength in the range of 420 to 480 nm (blue light), the pixel portion formed by the non-emissive dispersion can be a blue pixel portion.

The non-luminescent dispersion preferably contains light-scattering particles. When the non-emissive dispersion contains light-scattering particles, the pixel portion formed by the non-emissive dispersion can scatter the light incident on the pixel portion, whereby the light incident on the pixel portion can be scattered from the pixel portion. It is possible to reduce the difference in light intensity of the emitted light at the viewing angle.

<Light conversion layer, color filter and light emitting element>
Another embodiment of the present invention is a light conversion layer, a color filter and a light emitting device. Hereinafter, the details of the optical conversion layer and the color filter obtained by using the dispersion or the dispersion set of the above-described embodiment will be described with reference to the drawings. However, the following embodiment is an embodiment when the dispersion contains light-scattering particles. In the following description, the same reference numerals will be used for the same or equivalent elements, and duplicate description will be omitted.

FIG. 1 is a schematic cross-sectional view of the color filter of one embodiment. As shown in FIG. 1, the color filter 100 includes a base material 40 and a light conversion layer 30 provided on the base material 40. The light conversion layer 30 includes a plurality of pixel units 10 and a light-shielding unit 20.

The optical conversion layer 30 has a first pixel unit 10a, a second pixel unit 10b, and a third pixel unit 10c as the pixel unit 10. The first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c are arranged in a grid pattern so as to repeat in this order. The light-shielding portion 20 is located between adjacent pixel portions, that is, between the first pixel portion 10a and the second pixel portion 10b, between the second pixel portion 10b and the third pixel portion 10c, and the third. It is provided between the pixel portion 10c of the above and the first pixel portion 10a. In other words, these adjacent pixel portions are separated from each other by the light-shielding portion 20.

The first pixel portion 10a and the second pixel portion 10b are luminescent pixel portions (light emitting pixel portions) containing the cured product of the dispersion of the above-described embodiment, respectively. The cured product shown in FIG. 1 contains luminescent particles, a curing component, and light scattering particles. The first pixel portion 10a includes a first curing component 13a, a first luminescent particle 11a and a first light scattering particle 12a dispersed in the first curing component 13a, respectively. Similarly, the second pixel portion 10b includes a second curing component 13b and a second luminescent particle 11b and a second light scattering particle 12b dispersed in the second curing component 13b, respectively. .. The curing component is a component obtained by polymerizing a photopolymerizable compound, and includes a polymer of the photopolymerizable compound. In addition to the above polymer, the cured component may contain a component other than the organic solvent contained in the dispersion. In the first pixel portion 10a and the second pixel portion 10b, the first curing component 13a and the second curing component 13b may be the same or different, and may be the same as or different from the first light scattering particles 12a. It may be the same as or different from the second light-scattering particle 12b.

The first luminescent particles 11a are red luminescent nanocrystal particles that absorb light having a wavelength in the range of 420 to 480 nm and emit light having a emission peak wavelength in the range of 605 to 665 nm. That is, the first pixel portion 10a may be paraphrased as a red pixel portion for converting blue light into red light. The second luminescent particle 11b is a green luminescent nanocrystal particle that absorbs light having a wavelength in the range of 420 to 480 nm and emits light having a emission peak wavelength in the range of 500 to 560 nm. That is, the second pixel portion 10b may be paraphrased as a green pixel portion for converting blue light into green light.

The content of the luminescent particles in the luminescent pixel portion is preferably based on the total mass of the cured product of the luminescent dispersion from the viewpoint of being superior in the effect of improving the external quantum efficiency and obtaining excellent emission intensity. It is 10% by mass or more, 15% by mass or more, or 20% by mass or more. The content of the luminescent particles is preferably 50% by mass or less, 45, based on the total mass of the cured product of the luminescent dispersion, from the viewpoint of excellent reliability of the pixel portion and excellent emission intensity. It is 0% by mass or less, or 40% by mass or less.

The content of the light-scattering particles in the luminescent pixel portion is 0.1% by mass or more and 1% by mass or more based on the total mass of the cured product of the luminescent dispersion from the viewpoint of being more excellent in the effect of improving the external quantum efficiency. Alternatively, it may be 3% by mass or more. The content of the light-scattering particles is 60% by mass or less, 50% by mass, based on the total mass of the cured product of the luminescent dispersion, from the viewpoint of improving the effect of improving the external quantum efficiency and the reliability of the pixel portion. % Or less, 40% by mass or less, 30% by mass or less, 25 parts by mass or less, 20 parts by mass or less, or 15% by mass or less.

The third pixel portion 10c is a non-light emitting pixel portion (non-light emitting pixel portion) containing the cured product of the non-luminescent dispersion described above. The cured product does not contain luminescent particles, but contains light-scattering particles and a cured component. That is, the third pixel portion 10c includes a third curing component 13c and a third light scattering particle 12c dispersed in the third curing component 13c. The third curing component 13c is, for example, a component obtained by polymerizing a polymerizable compound and contains a polymer of the polymerizable compound. The third light-scattering particle 12c may be the same as or different from the first light-scattering particle 12a and the second light-scattering particle 12b.

The third pixel portion 10c has a transmittance of 30% or more with respect to light having a wavelength in the range of, for example, 420 to 480 nm. Therefore, the third pixel unit 10c functions as a blue pixel unit when a light source that emits light having a wavelength in the range of 420 to 480 nm is used. The transmittance of the third pixel unit 10c can be measured by a microspectroscopy device.

The content of the light-scattering particles in the non-luminous pixel portion is 1% by mass or more based on the total mass of the cured product of the non-luminous dispersion from the viewpoint of being able to further reduce the difference in light intensity at the viewing angle. It may be 5% by mass or more, or 10% by mass or more. The content of the light-scattering particles may be 80% by mass or less, and 75% by mass or less, based on the total mass of the cured product of the non-luminescent dispersion, from the viewpoint of further reducing light reflection. It may be present, and may be 70% by mass or less.

The thickness of the pixel portion (first pixel portion 10a, second pixel portion 10b, and third pixel portion 10c) may be, for example, 1 μm or more, 2 μm or more, or 3 μm or more. You may. The thickness of the pixel portion (first pixel portion 10a, second pixel portion 10b, and third pixel portion 10c) may be, for example, 30 μm or less, 20 μm or less, or 15 μm or less. You may.

The light-shielding portion 20 is a so-called black matrix provided for the purpose of separating adjacent pixel portions to prevent color mixing and for the purpose of preventing light leakage from a light source. The material constituting the light-shielding portion 20 is not particularly limited, and the curing of the resin composition containing light-shielding particles such as carbon fine particles, metal oxides, inorganic pigments, and organic pigments in the binder polymer in addition to a metal such as chromium. Objects and the like can be used. The binder polymer used here includes one or a mixture of one or more resins such as polyimide resin, acrylic resin, epoxy resin, polyacrylamide, polyvinyl alcohol, gelatin, casein, and cellulose, photosensitive resin, and O / W. An emulsion-type resin composition (for example, an emulsion of reactive silicone) or the like can be used. The thickness of the light-shielding portion 20 may be, for example, 0.5 μm or more, and may be 10 μm or less.

The base material 40 is a transparent base material having light transmission, and is, for example, transparent glass substrate such as quartz glass, Pylex (registered trademark) glass, synthetic quartz plate, transparent resin film, optical resin film and the like. A flexible base material or the like can be used. Among these, it is preferable to use a glass substrate made of non-alkali glass that does not contain an alkaline component in the glass. Specifically, "7059 glass", "1737 glass", "Eagle 200 (registered trademark)" and "Eagle XG (registered trademark)" manufactured by Corning Inc., "AN100" manufactured by Asahi Glass Co., Ltd., manufactured by Nippon Electric Glass Co., Ltd. "OA-10G" and "OA-11" of the above are suitable. These are materials with a small thermal expansion rate and are excellent in dimensional stability and workability in high temperature heat treatment.

The color filter 100 provided with the above optical conversion layer 30 is suitably used when a light source that emits light having a wavelength in the range of 420 to 480 nm is used.

The color filter 100 can be manufactured, for example, by forming the light-shielding portion 20 in a pattern on the base material 40 and then forming the pixel portion 10 in the pixel portion-forming region partitioned by the light-shielding portion 20 on the base material 40. .. The pixel portion 10 has a step of selectively adhering a dispersion (inkjet ink) to a pixel portion forming region on the base material 40 by an inkjet method, a step of removing an organic solvent from the dispersion by drying, and a dispersion after drying. It can be formed by a method comprising a step of irradiating a body with active energy rays (for example, ultraviolet rays) and curing the dispersion to obtain a light emitting pixel portion. A luminescent pixel portion can be obtained by using the above-mentioned luminescent dispersion as the dispersion, and a non-luminescent pixel portion can be obtained by using the non-luminescent dispersion.

The method of forming the light-shielding portion 20 is to form a metal thin film such as chromium or a thin film of a resin composition containing light-shielding particles in a region serving as a boundary between a plurality of pixel portions on one surface side of the base material 40. However, a method of patterning this thin film and the like can be mentioned. The metal thin film can be formed by, for example, a sputtering method, a vacuum vapor deposition method, or the like, and the thin film of the resin composition containing the light-shielding particles can be formed, for example, by a method such as coating or printing. Examples of the method for patterning include a photolithography method.

Examples of the inkjet method include a bubble jet (registered trademark) method using an electric heat converter as an energy generating element, a piezo jet method using a piezoelectric element, and the like.

The luminescent particle-containing ink composition of the present invention can be cured by irradiation with active energy rays (for example, ultraviolet rays). As the irradiation source (light source), for example, a mercury lamp, a metal halide lamp, a xenon lamp, an LED or the like is used, but the LED is preferable from the viewpoint of reducing the heat load on the coating film and low power consumption.

The wavelength of the light to be irradiated is preferably 200 nm or more, and more preferably 440 nm or less. The light intensity is preferably 0.2 to 2 kW / cm ² , more preferably 0.4 to 1 kW / cm ² . A light intensity of less than 0.2 kW / cm ² cannot sufficiently cure the coating film, and a light intensity of 2 kW / cm ² or more causes unevenness in the curing degree between the surface and the inside of the coating film, resulting in smoothness of the coating film surface. It is not preferable because it is inferior in sex. The irradiation amount (exposure amount) of light is preferably 10 mJ / cm ² or more, and more preferably 4000 mJ / cm ² or less.
The coating film can be cured in the air or in an inert gas, but more preferably in an inert gas in order to suppress oxygen inhibition on the surface of the coating film and oxidation of the coating film. Examples of the inert gas include nitrogen, argon, carbon dioxide and the like. By curing the coating film under such conditions, the coating film can be completely cured, so that the external quantum efficiency of the obtained light conversion layer 9 can be further improved.

For example, the optical conversion layer is a pixel portion (blue) containing a cured product of a luminescent dispersion containing blue luminescent nanocrystal particles in place of the third pixel portion 10c or in addition to the third pixel portion 10c. A pixel unit) may be provided. Further, the optical conversion layer may include a pixel portion (for example, a yellow pixel portion) containing a cured product of a luminescent dispersion containing nanocrystal particles that emit light of a color other than red, green, and blue. .. In these cases, it is preferable that each of the luminescent particles contained in each pixel portion of the optical conversion layer has an absorption maximum wavelength in the same wavelength range.

Further, at least a part of the pixel portion of the light conversion layer may contain a cured product of a composition containing a pigment other than luminescent particles.

Further, the color filter may be provided with an ink-repellent layer made of a material having an ink-repellent property narrower than that of the light-shielding portion on the pattern of the light-shielding portion. Further, instead of providing an ink-repellent layer, a photocatalyst-containing layer as a wettable variable layer is formed in a solid coating shape in a region including a pixel portion forming region, and then light is applied to the photocatalyst-containing layer via a photomask. Irradiation may be performed for exposure to selectively increase the parental ink property of the pixel portion forming region. Examples of the photocatalyst include titanium oxide and zinc oxide.

Further, the color filter may be provided with an ink receiving layer containing hydroxypropyl cellulose, polyvinyl alcohol, gelatin, etc. between the base material and the pixel portion.

Further, the color filter may be provided with a protective layer on the pixel portion. This protective layer flattens the color filter and prevents the components contained in the pixel portion, or the components contained in the pixel portion and the components contained in the photocatalyst-containing layer from elution into the liquid crystal layer. It is provided. As the material constituting the protective layer, a material used as a known protective layer for a color filter can be used.

Further, in the manufacture of the color filter and the optical conversion layer, the pixel portion may be formed by a photolithography method instead of the inkjet method. In this case, first, the dispersion is coated on the base material in a layered manner to form a dispersion layer. Next, the dispersion layer is exposed in a pattern and then developed using a developing solution. In this way, a pixel portion made of a cured product of the dispersion is formed. Since the developer is usually alkaline, an alkali-soluble material is used as the material of the dispersion. However, in terms of material usage efficiency, the inkjet method is superior to the photolithography method. This is because, in principle, the photolithography method removes about two-thirds or more of the material, which wastes the material. Therefore, in the present embodiment, it is preferable to use an inkjet ink and form a pixel portion by an inkjet method.

Further, in addition to the above-mentioned luminescent particles, the pixel portion of the light conversion layer of the present embodiment may further contain a pigment having substantially the same color as the luminescent color of the luminescent particles. In order to contain the pigment in the pixel portion, the dispersion may contain the pigment.

Further, among the red pixel portion (R), the green pixel portion (G), and the blue pixel portion (B) in the optical conversion layer of the present embodiment, one or two types of luminescent pixel portions are luminescent particles. It may be a pixel portion containing a coloring material without containing the above. As the color material that can be used here, a known color material can be used. For example, as the color material used for the red pixel portion (R), a diketopyrrolopyrrole pigment and / or an anionic red organic dye is used. Can be mentioned. Examples of the coloring material used for the green pixel portion (G) include at least one selected from the group consisting of a halogenated copper phthalocyanine pigment, a phthalocyanine-based green dye, and a mixture of a phthalocyanine-based blue dye and an azo-based yellow organic dye. Examples of the coloring material used for the blue pixel portion (B) include an ε-type copper phthalocyanine pigment and / or a cationic blue organic dye. The amount of these coloring materials used is 1 to 5% by mass based on the total mass of the pixel portion (cured product of the dispersion) from the viewpoint of preventing a decrease in transmittance when contained in the optical conversion layer. Is preferable.

The color filter can be used for a color filter such as an organic EL element (OLED) which is a light emitting element and a liquid crystal display element. In the present invention, it is particularly useful as an organic EL element (OLED), and the configuration of the organic EL element will be briefly described below.

The light emitting element, which is an organic EL element, has an organic EL light source unit partitioned for each pixel on the substrate, and the blue light emitted from the organic EL light source unit is red (R) above the organic EL light source unit. ), A light emitting element provided with a color filter that converts to green (G). The organic EL light source unit partitioned for each pixel may have a packed layer and a protective layer together with the organic EL light emitting member.

Such a light emitting element absorbs and re-emits or transmits the light emitted from the organic EL light source unit (EL layer) by the color filter, and extracts it as red light, green light, or blue light from the upper substrate side to the outside. Can be done.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Luminescent particles>
First, hollow silica particles (“SiliNax SP-PN (b)” manufactured by Nittetsu Mining Co., Ltd.) were dried under reduced pressure at 150 ° C. for 8 hours. Next, 200.0 parts by mass of dried hollow silica particles were weighed into a Kiriyama funnel. The average outer diameter of the hollow silica particles was 80 to 130 nm, and the average inner diameter was 50 to 120 nm.
Next, under an argon atmosphere, 63.9 parts by mass of cesium bromide, 110.1 parts by mass of lead (II) bromide and 3000 parts by mass of N-methylformamide were supplied to the reaction vessel at 50 ° C. for 30 minutes. By stirring, a lead cesium tribromide solution was obtained.
Next, the obtained lead tribromide cesium solution was added to the hollow silica particles and impregnated, and then the excess lead tribromide cesium solution was removed by filtration to recover the solid matter. Then, the obtained solid material was dried under reduced pressure at 150 ° C. for 1 hour to obtain luminescent particles (212.7 parts by mass) in which perovskite-type lead cesium tribromide crystals were contained in hollow silica particles.

<Polymer>
In addition to the luminescent particles obtained above, the block copolymers (A-1) to (A-3) below have the following block copolymers as block copolymers having a structural unit having a basic group and a prosolvent structural unit. Coalescence was used. For comparison, the block copolymer of (a-1) was used as a block copolymer having a pro-solvent structural unit but not having a structural unit having a basic group.
(A-1) A block copolymer containing vinylpyridine as a basic monomer unit and a polyethylene glycol structure as a prosolvent monomer unit (amine value: 40 mgKOH / g, acid value: 0 mgKOH / g). , EFKA PX-4701, manufactured by BASF Japan Co., Ltd.)
(A-2) A simple monomer unit containing a monomer unit having an aliphatic amino group as a basic monomer unit and having an aliphatic alkyl group having a linear structure or a branched structure as a prosolvent monomer unit. Block copolymer containing a weight unit (amine value: 4 mgKOH / g, acid value: 0 mgKOH / g, DISPERBYK-2008, manufactured by Big Chemie Japan Co., Ltd.)
(A-3) A block copolymer containing allylamine as a basic monomer unit and a monomer unit having a lactone-modified hydroxy group as a prosolvent monomer unit (amine value: 10 mgKOH / g, acid). Value: 17 mgKOH / g, Azispar PB821, manufactured by Ajinomoto Fine Techno Co., Ltd.)
(A-1) A polymer that does not contain a basic monomer unit, contains phosphoric acid as a monomer having an acidic group, and contains a polyethylene glycol structure as a prosolvent structural unit (amine value: 0 mgKOH). / G, Acid value: 129 mgKOH / g, DISPERBYK-111, manufactured by Big Chemie Japan Co., Ltd.)

<Photopolymerizable compound>
(B-1) Isobornyl methacrylate (light ester IB-X, viscosity: 6 mPa · s / 25 ° C., SP value: 8.70)
(B-2) Lauryl methacrylate (light ester L, viscosity: 3-8 mPa · s / 25 ° C., SP value: 9.02)
(B-3) Phenoxyethyl methacrylate (light ester PO, viscosity: 7 mPa · s / 25 ° C., SP value: 9.68)
(B-4) 1,6-Hexanediol dimethacrylate (light ester 1,6-HX, viscosity: 5-6 mPa · s / 25 ° C., SP value: 9.48)
(B-5) Dimethylol-tricyclodecanediacrylate (light acrylate DCP-A, viscosity: 130-170 mPa · s / 25 ° C., SP value: 9.68)
(B-1) Hydroxyethyl methacrylate (light ester HO-250, viscosity: 7 mPa · s / 25 ° C., SP value: 12.06)
(B-1) to (B-5) and (b-1) are all manufactured by Kyoeisha Chemical Co., Ltd.

<Photopolymerization initiator>
(C-1) 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (Omnirad TPO-H, manufactured by IGM Resins)
(C-2) Bis (2,4,6-trimethylbenzoyl) Phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins)

<Antioxidant>
(D-1) Phenolic Antioxidant (Irganox1010, manufactured by BASF Japan Ltd.)
(D-2) Hypophosphorous acid diester antioxidant (Hostanox P-EPQ, manufactured by Clariant Chemicals)

<Dispersion of light-scattering particles>
3 parts by mass of titanium oxide particles (average particle diameter: 210 nm, manufactured by Ishihara Sangyo Co., Ltd., CR-60-2) and 4.2 parts by mass of phenoxyethyl methacrylate (light ester PO, viscosity: 7 mPa · s / 25 ° C.) , SP value: 9.68) and 0.3 parts by mass of a polymer dispersant (EFKA PX-4701, manufactured by BASF Japan Co., Ltd.) were blended. Zirconia beads (diameter: 0.3 mm) were added to the obtained formulation, and then the mixture was shaken for 2 hours using a paint conditioner to disperse the formulation. As a result, a light-scattering particle dispersion was obtained.

(Examples 1 to 11 and Comparative Examples 1 to 4)
[Preparation of dispersion]
The luminescent particles, the polymer, and the photopolymerizable compound are mixed so as to have the composition (unit: parts by mass) shown in Table 1, and using a paint conditioner with a cooling function, the media diameter: 0.6 mm, the dispersion time: The dispersions of Examples 1 to 11 and Comparative Examples 1 to 4 were prepared by dispersing the luminescent particles under the conditions of a dispersion temperature of 25 ° C. for 30 minutes.

[Evaluation of dispersibility]
The dispersibility immediately after dispersion and after storage was evaluated by the following procedure. The results are shown in Table 1.

(Immediately after dispersion)
Within 30 minutes after preparation, the volume average particle size D50 of each of the obtained dispersions was measured using a nanoparticle size measuring device (Nanotrac Wave II, manufactured by Microtrac Bell Co., Ltd.). The smaller the D50, the better the dispersibility.

(After storage)
After storing each dispersion at 40 ° C. for 2 weeks, the presence or absence of a precipitate was visually confirmed on the bottom surface of the container. The dispersibility was evaluated according to the following evaluation criteria.
A: No precipitate is formed.
B: A precipitate is formed, but the precipitate is immediately redispersed by shaking.
C: A precipitate is formed. It does not redisperse immediately after shaking, but the precipitate disappears after shaking for 10 minutes.
D: A precipitate has formed, and the precipitate and the liquid component are completely separated. Precipitation remains even after shaking.

[Evaluation of optical characteristics]
To each of the obtained dispersions, the photopolymerizable compound used for each dispersion was added so that the concentration of the luminescent particles was 200 mass ppm. The optical properties of each dispersion were evaluated by measuring the photoluminescence quantum yield (PLQY) of the obtained solution with the absolute PL quantum yield measuring device "Quantumus-QY" (manufactured by Hamamatsu Photonics Co., Ltd.). .. The results are shown in Table 1.

As shown in Table 1, an embodiment containing both a photopolymerizable compound having an SP value of 10.0 or less and a block copolymer having a structural unit having a basic group and a prosolvent structural unit. The dispersions of Examples 1 to 11 are excellent in dispersibility immediately after preparation and dispersion stability after storage for 2 weeks. Further, since the photoluminescence quantum yield (PLQY) is large and the optical characteristics are excellent, it can be expected that better light emission can be obtained when an optical conversion layer is produced using the dispersion.

On the other hand, Comparative Examples 1 to 3 containing no such block copolymer have lower dispersibility immediately after preparation and dispersion stability after storage for 2 weeks as compared with Examples 1 to 11, and also has PLQY. low. It is considered that this is because the dispersibility of the luminescent particles is low and the PLQY is lowered. Further, the dispersion of Comparative Example 4 containing such a block copolymer but containing a photopolymerizable compound having an SP value of more than 10.0 has a dispersibility immediately after preparation as compared with Examples 1 to 11. And the dispersion stability after storage for 2 weeks is similar, but the PLL is low. It is considered that this is because the perovskite-type nanocrystal particles deteriorated and the PLQY decreased due to the absorption of moisture by the dispersion of Comparative Example 4.

(Examples 12 to 17)
The composition (unit: parts by mass) shown in Table 2 shows the dispersion of the photopolymerizable compound, the photopolymerization initiator, the antioxidant, and the light-scattering particles with respect to the dispersions of Examples 1 to 3, 8 and 9. In addition, each dispersion (ink composition) of Examples 12 to 16 is stirred with a laboratory mixer under the conditions of rotation speed: 500 rpm, stirring time: 15 minutes, and stirring temperature: 25 ° C. Was prepared. Moreover, the ink composition of Example 17 was prepared so as to have the composition shown in Table 2.

[Evaluation of dispersibility]
For each of the obtained dispersions (ink compositions), the dispersibility after storage was evaluated by the method described above. The results are shown in Table 2.

[Evaluation of optical properties of coating film]
The obtained ink composition was applied onto a glass substrate (“EagleXG®” manufactured by Corning Inc.) with a spin coater so that the film thickness after drying was 10 μm. The obtained coating film was irradiated with ultraviolet light having a wavelength of 395 nm with an LED lamp under a nitrogen atmosphere at an integrated exposure amount of 10 J / cm ² and an intensity of 1 W / cm ² , to obtain a cured product.
An integrating sphere is installed above the blue LED (peak emission wavelength: 450 nm) manufactured by CCS Co., Ltd. as a surface emission light source, and a radiation spectrophotometer manufactured by Otsuka Electronics Co., Ltd. (trade name "MCPD-9800") is placed on this integrating sphere. ") Was connected. Next, each cured product was inserted between the blue LED and the integrating sphere, the blue LED was turned on, and the observed spectrum and the illuminance at each wavelength were measured by a radiation spectrophotometer. External quantum efficiency (initial EQE) was determined from the obtained spectrum and illuminance. Further, after the cured product was stored at 40 ° C. for 2 weeks, the external quantum efficiency (EQE after storage) of the cured product after storage was measured in the same manner. From each measured EQE, the retention rate was calculated by the following formula, and the optical characteristics of the coating film were evaluated. The results are shown in Table 2.
EQE retention rate (%) = EQE after storage / initial EQE x 100

[Evaluation of Viscosity Stability of Ink Composition]
The viscosity (initial viscosity η0) of each obtained ink composition at 30 ° C. was measured using an E-type viscometer. Further, the viscosity (viscosity η1 after storage) at 30 ° C. after storing each ink composition in a constant temperature bath at 40 ° C. for 1 week was measured using an E-type viscometer. From each measured viscosity, the viscosity increase rate was calculated by the following formula. The results are shown in Table 2.
Viscosity increase rate (%) = (η1-η0) / η0 × 100

[Evaluation of surface smoothness]
The surface roughness (Sa value; unit μm) of the cured product obtained in the same manner as above was measured using VertScan3.0R4300 of Ryoka System Co., Ltd. The results are shown in Table 2.

As shown in Table 2, in addition to luminescent particles, a block copolymer having a basic group, and a photopolymerizable compound, a photopolymerization initiator, an antioxidant, and a light scattering particle are contained. All of the dispersions (ink compositions) of Examples 12 to 17 are excellent in dispersion stability after storage for 2 weeks and excellent in viscosity stability after storage for 1 week. Further, all of the cured products produced by the dispersions of Examples 12 to 17 have excellent surface smoothness, excellent external quantum efficiency (EQE), and excellent optical properties.

10 ... pixel unit, 10a ... first pixel unit, 10b ... second pixel unit, 10c ... third pixel unit, 11a ... first light emitting particle, 11b ... second light emitting particle, 12a ... second 1 light-scattering particle, 12b ... second light-scattering particle, 12c ... third light-scattering particle, 20 ... light-shielding portion, 30 ... light conversion layer, 40 ... base material, 100 ... color filter.

Claims

Hollow silica particles having an inner space, and luminescent particles having semiconductor nanocrystal particles made of metal halide contained in the inner space, and
Photopolymerizable compounds having a solubility parameter (SP value) of 10.0 or less, and
A block copolymer having a first structural unit having a basic group and a second structural unit having an affinity for the photopolymerizable compound,
Luminous particle dispersion containing.
The luminescent particle dispersion according to claim 1, wherein the photopolymerizable compound contains one or more monofunctional (meth) acrylates.
The luminescent particle dispersion according to claim 1 or 2, wherein the amine value of the block copolymer is 2 mgKOH / g or more and 70 mgKOH / g or less.
The luminescent particle dispersion according to any one of claims 1 to 3, further containing a photopolymerization initiator.
The luminescent particle dispersion according to any one of claims 1 to 4, further containing light-scattering particles.
The luminescent particle dispersion according to any one of claims 1 to 5, which is used as an ink jet ink.
A plurality of pixel portions and a light-shielding portion provided between the plurality of pixel portions are provided.
The plurality of pixel portions are a light conversion layer having a luminescent pixel portion containing a cured product of the luminescent particle dispersion according to any one of claims 1 to 6.
A color filter including the optical conversion layer according to claim 7.
A light emitting device including the color filter according to claim 8.