JP2023036187A - Light-emitting nanoparticle composite, ink composition, optical conversion layer, and color filter - Google Patents

Abstract

To provide a light-emitting nanoparticle composite having excellent atmospheric storage stability and heat resistance, especially excellent external quantum efficiency, and to provide: an ink composition which comprises such a light-emitting nanoparticle composite, has excellent dispersibility, and can prevent deterioration of light-emitting characteristics; an optical conversion layer having excellent light-emitting characteristics; and a color filter.SOLUTION: Provided is a light-emitting nanoparticle composite having organic ligands coordinated on the surface of light-emitting nanoparticles, where the organic ligand is a compound represented by the following formula (1) and has a molecular weight of 200 to 350.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to luminescent nanoparticle composites, ink compositions, light conversion layers and color filters.

Liquid crystal display devices are widely used for applications such as mobile terminals, televisions, and monitors. Color filters used in these liquid crystal display devices are manufactured by a photolithographic method that forms a black matrix and red, green and blue pixel patterns. Specifically, in the photolithography method, a photosensitive resin composition containing coloring materials such as pigments and dyes is coated on a substrate, dried, mask-exposed with UV irradiation, and uncured portions are removed by alkali development. Firing is then performed. Further, in recent years, self-luminous display devices in which an organic EL element that emits white light and a color filter are combined are also widely used for applications such as televisions and monitors.

However, in display devices using these color filters, in principle, at least 67% of the light is absorbed by the color filters, so there is a fundamental limit to reducing power consumption by improving the transmittance of the color filters themselves. there were.

In order to solve the problem of low power consumption, in recent years, a method of using quantum dots, which are luminescent nanocrystal particles, in the light conversion layer instead of conventional color filters has attracted attention.
This light conversion layer comprises a red-emitting quantum dot layer that emits red fluorescence when excited by blue light and a green-emitting quantum dot layer that emits green fluorescence when excited by blue light, on a substrate on which a black matrix is formed. and a blue-light-transmitting layer that transmits blue light. A liquid crystal display device or a self-luminous display device is configured by combining such a light conversion layer with an LED backlight that emits blue light or an organic EL element that emits blue light.

A display device having such a light conversion layer can increase light utilization efficiency as compared with a display device having a conventional color filter. In addition, since fluorescence emitted from the quantum dots and having a spectrum with a small half-value width can be used as it is for color display of the display device, the display device can have a wide color reproduction range.

For example, the light conversion layer is formed by forming a coating film on one side of the substrate using a photosensitive resin composition containing quantum dots, patterning the resulting coating film by a photolithography method, and then heat-treating the resulting coating film. A method of producing by curing is known (see, for example, Patent Document 1).
However, according to the photolithography method, the number of steps is large and complicated, and since the photosensitive resin composition is removed by alkali development, raw materials are inevitably wasted.

A manufacturing method using an inkjet method is known as a method capable of reducing waste of raw materials. According to the inkjet method, the red light-emitting quantum dot layer and the green light-emitting quantum dot layer in the light conversion layer can be formed at the same time, so that the manufacturing efficiency can be improved. In addition, since all of the ejected ink (photosensitive resin composition) can be used, waste of raw materials such as in photolithography is less likely to occur. For example, as an inkjet ink in which quantum dots are dispersed, an example of use for patterning a light conversion layer used in combination with an organic EL element emitting blue light is disclosed (see, for example, Patent Document 2).
On the other hand, from the viewpoint of the optical properties of the light conversion layer (for example, improving the external quantum efficiency (EQE)), an ink composition with an increased content of luminescent nanocrystalline particles has been proposed (see, for example, Patent Document 3). ). It has also been proposed that the dispersion stability and optical properties can be improved by surface-treating luminescent nanocrystalline particles with a specific compound and having the compound as a ligand on at least part of the surface (for example, , see Patent Document 4).

JP 2016-53716 A WO2008/001693 WO2020/162552 JP 2020-105491 A

Ink compositions containing quantum dots and their film-formed products have the problem of deterioration due to oxygen and moisture contained in the atmosphere. When an ink composition containing quantum dots is supplied to a large area to produce a coated or printed matter, completely isolating them from the atmosphere makes it possible to use most of the coating and printing devices with high purity. There is no other choice but to place it under an inert gas atmosphere, which requires a huge capital investment.
In addition, it is required that the external quantum efficiency does not decrease (heat resistance) due to heating in the manufacturing process of the pixel portion. It cannot be said that a pixel portion is obtained.

According to the studies of the present inventors, regarding the method of surface-treating quantum dots, which are luminescent nanocrystalline particles, with a specific compound, the stability of the external quantum efficiency of carboxylic acid compounds during atmospheric storage and during heating is still unclear. It turned out that there was room for improvement.
An object of the present invention is to provide a luminescent nanoparticle composite that is excellent in atmospheric storage stability and heat resistance, and particularly excellent in stability in maintaining external quantum efficiency. Another object of the present invention is to provide an ink composition containing such a luminescent nanoparticle composite, which is excellent in dispersibility and capable of preventing deterioration in light emission properties, a light conversion layer and a color filter which are excellent in light emission properties. It is in.

The present inventors have found that the atmospheric storage stability and heat resistance can be improved by using a carboxylic acid compound having a specific chemical structure in a luminescent nanoparticle composite, and have completed the present invention.

That is, one aspect of the present invention is a luminescent nanoparticle complex in which an organic ligand is coordinated to the surface of a luminescent nanoparticle, wherein the organic ligand is represented by the following formula (1) and has a molecular weight of 200 to 350 compound.

［式（１）中、Ｒ^１は、炭素原子数１～６のアルキレン基を表し、該アルキレン基中の１個または隣り合わない２個以上の－ＣＨ_２－は、独立して、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＯＣＯ－、－ＮＨ－、－ＣＯＮＨ－または－ＮＨＣＯ－のいずれかに置換されていても良く、Ｒ^２は、炭素原子数１～１０のアルキレン基または（ポリ）オキシアルキレン基を表し、Ｘは、環式構造を有する置換基を表す。］

[In formula (1), R ¹ represents an alkylene group having 1 to 6 carbon atoms, and one or more non-adjacent -CH ₂ - in the alkylene group are independently -O -, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH- or -NHCO-, and R ² has 1 to 10 carbon atoms represents an alkylene group or (poly)oxyalkylene group, and X represents a substituent having a cyclic structure. ]

According to the luminescent nanoparticle composite of the aspect described above, it is possible to form an ink composition that is excellent in dispersibility and that can prevent deterioration of luminous properties, a light conversion layer that is excellent in luminous properties, and a color filter.

One aspect of the present invention is that X in formula (1) is an aryl group.

In one aspect of the present invention, the Hansen solubility parameter δD value of the organic ligand is 17.4 MPa ^0.5 or greater.

In one aspect of the invention, the luminescent nanoparticles are core-shell structured luminescent nanoparticles containing indium and phosphorus in the core.

One aspect of the present invention is an ink composition containing the above-described luminescent nanoparticle composite and a photopolymerizable compound.

In one aspect of the invention, the photopolymerizable compound is a photoradically polymerizable compound.

One aspect of the invention is that the photopolymerizable compound is alkali-insoluble.

In one aspect of the invention, the ink composition contains an antioxidant.

In one aspect of the present invention, the ink composition contains a zinc compound having zinc as a central metal and two ligands coordinated to the zinc.

In one aspect of the present invention, the ink composition is used for a droplet ejection method by an inkjet system.

In one aspect of the present invention, the ink composition is for color filters.

One aspect of the present invention relates to a light conversion layer comprising a cured product of the ink composition described above.

One aspect of the invention is that the light conversion layer is alkali-insoluble.

According to one aspect of the present invention, the light conversion layer has a plurality of pixel portions, and the plurality of pixel portions includes a cured product of the ink composition described above.

In one aspect of the present invention, the light conversion layer further includes a light shielding portion provided between the plurality of pixel portions, and the plurality of pixel portions includes a cured product of the ink composition described above, and a luminescent nanoparticle composite as a first pixel portion containing a luminescent nanoparticle composite that absorbs light with a wavelength in the range of 420 to 480 nm and emits light with an emission peak wavelength in the range of 605 to 665 nm; and a luminescent nanoparticle composite and a second pixel portion containing a luminescent nanoparticle composite that absorbs light with a wavelength in the range of 420 to 480 nm and emits light with an emission peak wavelength in the range of 500 to 560 nm.

According to one aspect of the present invention, the light conversion layer includes a third pixel section having a transmittance of 30% or more for light with a wavelength in the range of 420 to 480 nm.

In one aspect of the invention, the light conversion layer is a color filter.

According to the present invention, a luminescent nanoparticle composite that is excellent in atmospheric storage stability and heat resistance, and particularly excellent in stability in maintaining external quantum efficiency, contains such a luminescent nanoparticle composite, is excellent in dispersibility, and emits light. It is possible to provide an ink composition capable of preventing deterioration of properties, a light conversion layer and a color filter excellent in light emission properties.

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

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In this specification, a numerical range indicated using "-" indicates a range including the numerical values before and after "-" as the minimum and maximum values, respectively.

The present invention provides a luminescent nanoparticle complex in which an organic ligand is coordinated to the surface of a luminescent nanoparticle, wherein the organic ligand is a compound represented by the following formula (1) and having a molecular weight of 200 to 350. A luminescent nanoparticle composite characterized by:

［式（１）中、Ｒ^１は、炭素原子数１～６のアルキレン基を表し、該アルキレン基中の１個または隣り合わない２個以上の－ＣＨ_２－は、独立して、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＯＣＯ－、－ＮＨ－、－ＣＯＮＨ－または－ＮＨＣＯ－のいずれかに置換されていても良く、Ｒ^２は、炭素原子数１～１０のアルキレン基または（ポリ）オキシアルキレン基を表し、Ｘは、環式構造を有する置換基を表す。］

[In formula (1), R ¹ represents an alkylene group having 1 to 6 carbon atoms, and one or more non-adjacent -CH ₂ - in the alkylene group are independently -O -, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH- or -NHCO-, and R ² has 1 to 10 carbon atoms represents an alkylene group or (poly)oxyalkylene group, and X represents a substituent having a cyclic structure. ]

The luminescent nanoparticle composite of the present invention is used, for example, in an ink composition for forming a pixel portion of a light conversion layer of a color filter or the like. That is, the luminescent nanoparticle composite of the invention is preferably used in an ink composition for forming a light conversion layer (for example, for forming a color filter pixel portion). Such an ink composition is excellent in dispersibility of the luminescent nanoparticle composite and can prevent deterioration of optical properties.
Although the reason why the above effects are obtained is not clear, the present inventors speculate as follows.

Due to their rigid molecular structure, organic ligands having a cyclic structure have restricted molecular motion compared to linear or branched organic ligands. Therefore, when the organic ligand having a cyclic structure is coordinated to the surface of the light-emitting nanoparticle, generation of radicals during atmospheric storage or heating is suppressed.
Furthermore, when an organic ligand with a molecular weight below a certain level is used, a cyclic structure is introduced at high density near the luminescent nanoparticles, increasing the cohesive energy density and increasing the permeability to gases such as oxygen and moisture. descend.
Therefore, since radicals, oxygen, and moisture that cause oxidation of surface elements of the luminescent nanoparticles are reduced, luminescent nanoparticles in which an organic ligand having a cyclic structure with a molecular weight below a certain level is coordinated to the luminescent nanoparticles. The composite is inhibited from being deteriorated due to oxidation of surface elements, and is excellent in maintaining stability of the external quantum efficiency during atmospheric storage and heating.

In addition, by using a carboxylic acid compound having a specific structure as an organic ligand, affinity with both the light-emitting nanoparticles and the photopolymerizable compound is increased, and these can be uniformly distributed in the ink composition. .
Therefore, the luminescent nanoparticle composite can be uniformly dispersed in the ink composition, and deterioration of the luminescent nanoparticles can be prevented.
As a result, according to the present invention, it is believed that it is possible to obtain an ink composition that is excellent in the dispersibility of the luminescent nanoparticle composite and that can sufficiently prevent deterioration in optical properties. Such an effect of preventing deterioration of optical properties is suitably exhibited during storage of the ink composition, during fabrication of the pixel portion, and the like.

In addition, the ink composition containing the luminescent nanoparticle composite of the present invention provides a pixel portion having excellent external quantum efficiency. Furthermore, according to the ink composition of the present invention, since the luminescent nanoparticles are uniformly dispersed, excellent ejection stability can be obtained in a droplet ejection method by an inkjet system (hereinafter also referred to as an "inkjet method"). easy to get That is, the ink composition of the invention can be suitably used in the inkjet method.

Furthermore, according to the ink composition of the present invention, since the luminescent nanoparticle composite contains a specific carboxylic acid compound, the decrease in external quantum efficiency due to heating is suppressed. That is, according to the ink composition of the present invention, it is easy to form a pixel portion excellent in heat resistance (stability of external quantum efficiency).

The ink composition of one embodiment can be applied as an ink for manufacturing a color filter. In view of the fact that a pixel portion (light conversion layer) can be formed only by using a necessary amount, it is preferable to prepare and use it so as to be suitable for the inkjet method rather than the photolithographic method. In addition to the luminescent nanoparticle composite and the photopolymerizable compound, such an ink composition may further contain other components such as light-scattering particles, a polymer dispersant, and an organic solvent, which will be described later, if necessary. can be done.

[Luminescent nanoparticle composite]
First, the luminescent nanoparticles and organic ligands that constitute the luminescent nanoparticle composite of the present invention will be described.

[Luminescent nanoparticles]
Luminescent nanoparticles are generally nano-sized crystals that absorb excitation light and emit fluorescence or phosphorescence. The luminescent nanoparticles are crystals having a maximum particle diameter of 100 nm or less as measured by a transmission electron microscope or a scanning electron microscope, for example.

Luminescent nanoparticles can, for example, emit light (fluorescence or phosphorescence) at a wavelength different from the absorbed wavelength by absorbing light of a given wavelength. The luminescent nanoparticles may be red luminescent nanocrystalline particles that emit light with an emission peak in the wavelength range of 605-665 nm (red light), and light with an emission peak in the wavelength range of 500-560 nm (green light), and may be blue-emitting nanocrystalline particles that emit light having an emission peak in the wavelength range of 420-480 nm (blue light).
In addition, the light absorbed by the luminescent nanoparticles is, for example, light in the wavelength range of 400 nm or more and less than 500 nm (particularly, wavelength 420 to 480 nm) (blue light) or light in the wavelength range of 200 nm to 400 nm (ultraviolet light). It can be.
The wavelength of the emission peak of the luminescent nanoparticles can be confirmed, for example, in the fluorescence spectrum or phosphorescence spectrum measured using a spectrofluorometer.

The red-emitting nanocrystalline particles have a wavelength of 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 or less. , preferably has an emission peak in the range of 632 nm or less or 630 nm or less, and has 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. preferable.
In addition, these upper limit and lower limit can be combined arbitrarily. In addition, in the following similar description, the upper limit and the lower limit individually described can be arbitrarily combined.

The green-emitting nanocrystalline particles have an emission peak 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 preferably has an emission peak in the 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.

The blue-emitting nanocrystalline particles have an emission peak 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 preferably has an emission peak in the 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.

According to the solution of the Schrödinger wave equation of the well-type potential model, the wavelength (emission color) of the light emitted by the luminescent nanoparticles depends on the size (e.g., particle diameter) of the luminescent nanoparticles. also depends on the energy gap of Therefore, the emission color can be selected (adjusted) by changing the constituent material and size of the luminescent nanoparticles used.

The luminescent nanoparticles may be luminescent nanoparticles comprising semiconductor materials (luminescent semiconductor nanoparticles). Such luminescent nanoparticles include quantum dots, quantum rods and the like. Among these, quantum dots are preferable as the luminescent nanoparticles from the viewpoint that the emission spectrum can be easily controlled, the reliability can be secured, the production cost can be reduced, and the mass productivity can be improved.

The luminescent nanoparticles constituting the luminescent nanoparticle composite of the present invention are core-shell structured luminescent nanoparticles containing indium (In) and phosphorus (P) in the core.
That is, the structure of the luminescent nanoparticles has a core containing In and P as a first semiconductor material and a shell covering at least part of the core and containing a second semiconductor material different from the first semiconductor material.
In addition to the shell containing the second semiconductor material (first shell), the luminescent nanoparticles cover at least a portion of this shell and contain a third semiconductor material different from the first and second semiconductor materials. It may further have (a second shell). In other words, the structure of the luminescent nanoparticles may be a structure consisting of a core, a first shell and a second shell (core/shell/shell structure).
Further, each of the core and shell may be a mixed crystal containing two or more semiconductor materials (eg, InP+GaP, ZnS+ZnSe, etc.).
Since the luminescent nanoparticle composite of the present invention contains In and P as constituent elements in the core, it has a narrow bandgap and can be suitably used for applications that emit visible light. By using a semiconductor material with a large bandgap for the shell, excitons (electron-hole pairs) generated by photoexcitation are confined within the core. As a result, the probability of non-radiative transitions on the surface of the luminescent nanoparticles is reduced, improving the stability of the external quantum efficiency.

Examples of the first semiconductor material containing In and P that constitute the core of the luminescent nanoparticles include InP, InNP, InPAs, InPSb, GaInP, GaInNP, GaInPAs, GaInPSb, InAlNP, InAlPAs and InAlPSb. .

The second semiconductor material or the third semiconductor material constituting the shell of the luminescent nanoparticles is a group II-VI semiconductor, a group III-V semiconductor, a group I-III-VI semiconductor, a group IV semiconductor and a group I-II- It preferably contains at least one semiconductor material selected from the group consisting of Group IV-VI semiconductors.

Specific semiconductor materials include, for example, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, ＣｄＺｎＳｅ、ＣｄＺｎＴｅ、ＣｄＨｇＳ、ＣｄＨｇＳｅ、ＣｄＨｇＴｅ、ＨｇＺｎＳ、ＨｇＺｎＳｅ、ＣｄＨｇＺｎＴｅ、ＣｄＺｎＳｅＳ、ＣｄＺｎＳｅＴｅ、ＣｄＺｎＳＴｅ、ＣｄＨｇＳｅＳ、ＣｄＨｇＳｅＴｅ、ＣｄＨｇＳＴｅ、ＨｇＺｎＳｅＳ、ＨｇＺｎＳｅＴｅ、ＨｇＺｎＳＴｅ；ＧａＮ、ＧａＰ、ＧａＡｓ、ＧａＳｂ、ＡｌＮ、ＡｌＰ、ＡｌＡｓ、ＡｌＳｂ、 InN, InP, InAs, InSb, GaInP, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb; SnPbSSe, SnPbSeTe _, SnPbSTe; Si, Ge, SiC, SiGe, _AgInSe2 , CuGaSe2, _CuInS2 , _CuGaS2 , _CuInSe2 , _AgInS2 , AgInGaS, _AgGaSe2 , AgGaS2 _, C, Si and Ge.

Luminous nanoparticles are CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, _HgS , HgSe, HgTe _{, InP} , _InAs , InSb, GaP, GaAs, _GaSb , _AgInS2 , AgInSe2, AgInTe2, AgInGaS, AgGaS2, _AgGaSe2 , AgGaTe2, CuInS2 _, CuSInSe2 _, CuInGe2 ₂ , _{CuGaSe2 , CuGaTe2} , Si, C, Ge and _Cu2ZnSnS4 .

Specific examples of the luminescent nanoparticles constituting the luminescent nanoparticle composite of the present invention include, for example, core/shell structured nanoparticles having an InP core and a ZnS shell, InP cores and ZnS and ZnSe core/shell structured nanoparticles with mixed crystal shells, cores of InP, core/shell/shell structured nanoparticles with first shells of ZnSe and second shells of ZnS, cores of InP, ZnS and ZnSe core/shell/shell structured nanoparticles with a mixed crystal first shell and a ZnS second shell; They can be used as red-emitting nanocrystalline particles, green-emitting nanocrystalline particles, and blue-emitting nanocrystalline particles.

By adjusting the average particle size of the luminescent nanoparticles themselves with the same chemical composition, the color to be emitted from the luminescent nanoparticles can be changed to red or green.
Moreover, it is preferable that the luminescent nanoparticles themselves have the least adverse effect on the human body or the like. Therefore, when using luminescent nanoparticles that do not contain cadmium, selenium, etc. as much as possible, or using luminescent nanoparticles containing the above elements (cadmium, selenium, etc.), it is necessary to reduce these elements as much as possible. In addition, it is preferable to combine with other luminescent nanoparticles.

The shape of the luminescent nanoparticles is not particularly limited and may be any geometric shape or any irregular shape. The shape of the luminescent nanoparticles may be, for example, spherical, ellipsoidal, pyramidal, disk-like, branch-like, net-like, rod-like, and the like.
However, as the luminescent nanoparticles, it is preferable to use particles with a less directional particle shape (e.g., spherical, tetrahedral, etc. particles) containing the luminescent nanoparticle composite of the present invention, which will be described later. It is preferable in that the uniformity and fluidity of the ink composition to be applied can be improved.

The average particle diameter (volume average diameter) of the luminescent nanoparticles is preferably 1 nm or more, preferably 1.5 nm or more, from the viewpoints of easily obtaining light emission of a desired wavelength and excellent dispersibility and storage stability. It is more preferably 2 nm or more, and more preferably 2 nm or more.
The average particle size of the luminescent nanoparticles is preferably 40 nm or less, more preferably 30 nm or less, and even more preferably 20 nm or less, from the viewpoint of easily obtaining light of a desired wavelength.
The average particle size (primary particle size) of the luminescent nanoparticles can be determined by directly observing a plurality of arbitrary luminescent nanoparticles using a transmission electron microscope (TEM) or a scanning electron microscope (SEM), and projecting two Each particle diameter is calculated from the ratio of length and breadth by the dimensional image, and the average value is obtained. The size and shape of the luminescent nanoparticles are considered to depend on their chemical composition, structure, manufacturing method, manufacturing conditions, and the like.

Particles that can be dispersed in a colloidal form in an organic solvent, a photopolymerizable compound, or the like can be suitably used as the luminescent nanoparticles. The organic solvent is as described below.
Commercially available products can also be used as the luminescent nanoparticles. Commercially available luminescent nanoparticles include, for example, indium phosphide/zinc sulfide manufactured by NN-Labs, D-dot, and InP/ZnS manufactured by Aldrich.

[Organic ligand]
The organic ligand that constitutes the luminescent nanoparticle composite of the present invention contains one or more carboxylic acid compounds having one or more carboxy groups (hereinafter also simply referred to as "carboxylic acid compounds"). In the luminescent nanoparticle composite of the present invention, the surface (shell portion) of the luminescent nanoparticles is passivated (modified) with a carboxylic acid compound.
Since the carboxylic acid compound as the organic ligand has a carboxy group (--COOH), it can be coordinately bonded to the surface of the luminescent nanoparticles.

A carboxylic acid compound is represented by the following formula (1).

［式（１）中、Ｒ^１は、炭素原子数１～６のアルキレン基を表し、該アルキレン基中の１個または隣り合わない２個以上の－ＣＨ_２－は、独立して、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＯＣＯ－、－ＮＨ－、－ＣＯＮＨ－または－ＮＨＣＯ－のいずれかに置換されていても良く、Ｒ^２は、炭素原子数１～１０のアルキレン基または（ポリ）オキシアルキレン基を表し、Ｘは、環式構造を有する置換基を表す。］

[In formula (1), R ¹ represents an alkylene group having 1 to 6 carbon atoms, and one or more non-adjacent -CH ₂ - in the alkylene group are independently -O -, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH- or -NHCO-, and R ² has 1 to 10 carbon atoms represents an alkylene group or (poly)oxyalkylene group, and X represents a substituent having a cyclic structure. ]

The alkylene group having 1 to 6 carbon atoms (including those substituted with —CH ₂ —) represented by R ¹ includes, for example, a methylene group, an ethylene group, a methylmethylene group, a methylethylene group, a trimethylene group, and a tetramethylene group. group, pentamethylene group, hexamethylene group, or groups represented by the following formulas (2-1) to (2-14), among which formula (2-1) and formula (2-2) , Formula (2-3), Formula (2-4), Formula (2-5), Formula (2-6), Formula (2-7) or Formula (2-8) is preferable, Formula (2-1 ) or formula (2-2) is more preferred.
An asterisk in formulas (2-1) to (2-14) represents a bond with an adjacent group.

Ｒ^２が表す炭素原子数１～１０のアルキレン基としては、例えば、メチレン基、エチレン基、メチルメチレン基、メチルエチレン基、トリメチレン基、テトラメチレン基、ペンタメチレン基等が挙げられ、炭素原子数１～１０の（ポリ）オキシアルキレン基としては、例えば、オキシエチレン基、オキシプロピレン基、オキシブチレン基、ポリオキシエチレン基、ポリオキシプロピレン基、ポリオキシブチレン基、オキシエチレン・オキシプロピレン共重合性基、ポリオキシブチレン基等が挙げられるが、メチレン基、オキシエチレン基またはポリオキシエチレン基が好ましく、オキシエチレン基またはポリオキシエチレン基がより好ましい。

Examples of the alkylene group having 1 to 10 carbon atoms represented by R ² include methylene group, ethylene group, methylmethylene group, methylethylene group, trimethylene group, tetramethylene group, pentamethylene group and the like, and the number of carbon atoms The (poly)oxyalkylene groups of 1 to 10 include, for example, oxyethylene group, oxypropylene group, oxybutylene group, polyoxyethylene group, polyoxypropylene group, polyoxybutylene group, oxyethylene/oxypropylene copolymerizable group, polyoxybutylene group and the like, preferably a methylene group, an oxyethylene group or a polyoxyethylene group, more preferably an oxyethylene group or a polyoxyethylene group.

Examples of substituents having a cyclic structure represented by X include an aryl group, an aryloxy group, an arylthio group, a heteroaryl group, a monocyclic or polycyclic cycloalkyl group, a monocyclic or polycyclic cycloalkyloxy group, and the like. mentioned. The substituent represented by X is preferably an aryl group or a monocyclic cycloalkyloxy group, more preferably an aryl group.

The carboxylic acid compound preferably has a δD value of 17.4 MPa ^0.5 or more in the Hansen solubility parameter (HSP value) from the viewpoint of easily obtaining a cured product excellent in the stability of maintaining the external quantum efficiency. .4 to 18.2 MPa ^0.5 is more preferred.
More preferably, the carboxylic acid compound has a Hansen solubility parameter (HSP value) of δP of 3 to 9 MPa ^0.5 and δH of 7 to 13 MPa ^0.5 .
Here, the Hansen solubility parameter is a parameter obtained by dividing the solubility parameter introduced by Hildebrand into three components δD, δP and δH and expressing them in a three-dimensional space. δD indicates the effect of nonpolar interaction, δP indicates the effect of dipole force, and δH indicates the effect of hydrogen bonding force. Hansen Solubility Parameter values for various compounds can be found, for example, in Charles M. et al. Hansen, "Hansen Solubility Parameters: A Users Handbook". Hansen Solubility Parameter values for compounds not listed can also be estimated using computer software (Hansen Solubility Parameters in Practice (HSPiP)).

By using a carboxylic acid compound having such a Hansen solubility parameter as an organic ligand, the affinity with both the luminescent nanoparticles and the photopolymerizable compound is increased, and these can be uniformly distributed in the ink composition. can. Therefore, the luminescent nanoparticle composite can be uniformly dispersed in the ink composition, and deterioration of the luminescent nanoparticles can be prevented.
As a result, according to the present invention, it is believed that an ink composition can be obtained in which the luminescent nanoparticle composite is excellent in dispersibility and the deterioration of optical properties can be sufficiently prevented. Such an effect of preventing deterioration of optical properties is suitably exhibited during storage of the ink composition, during fabrication of the pixel portion, and the like.

The carboxylic acid compound has a molecular weight of 200 to 350, preferably 250 or more.
By using a carboxylic acid compound having a molecular weight of 250 or more as an organic ligand, it is believed that an ink composition that can prevent thickening during storage of the ink composition can be obtained. In addition, the molecular weight of the carboxylic acid compound is preferably 350 or less, more preferably 320 or less, from the viewpoints of easily obtaining an appropriate viscosity as an inkjet ink and maintaining light-emitting properties.
The molecular weight of the carboxylic acid compound can be determined by GC-MS, GPC or ¹ HNMR. The molecular weight of the carboxylic acid compound having a molecular weight distribution is preferably determined by ¹ HNMR, and the number average molecular weight is preferably 200-350.

Specific examples of suitable carboxylic acid compounds include the following compounds.

The luminescent nanoparticle composite of the present invention can be obtained by mixing the luminescent nanoparticles described above and a carboxylic acid compound, preferably in an organic solvent to be described later.
The amount of the carboxylic acid compound used as the organic ligand is 10 parts by mass or more with respect to 100 parts by mass of the luminescent nanoparticles, from the viewpoint of the dispersion stability of the resulting luminescent nanoparticle composite and the maintenance of the luminescent properties. It may be 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, or 40 parts by mass or more. The amount of the carboxylic acid compound used may be 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, or 30 parts by mass or less with respect to 100 parts by mass of the luminescent nanoparticles.
From these viewpoints, the amount of the carboxylic acid compound used may be, for example, 10 to 50 parts by mass, or may be 20 to 40 parts by mass, relative to 100 parts by mass of the luminescent nanoparticles.

Further, a carboxylic acid compound having a Hansen solubility parameter δD deviating from the above range and other organic ligands may be used in combination as long as the effect of the present invention is not impaired. Such other organic ligands include, for example, TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, linoleic acid, linolenic acid, ricinoleic acid, gluconic acid, 16-hydroxyhexadecanoic acid, 12-hydroxystearin. acid, N-lauroylsarcosine, N-oleylsarcosine, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), phenylphosphonic acid, and octylphosphinic acid (OPA).

The configuration of the ink composition of the present invention, which contains the luminescent nanoparticle composite of the present invention and a photopolymerizable compound, will be described below. The present invention is not limited to these configurations, and any other configuration may be added or replaced with any configuration that exhibits similar functions.
In the present specification, the term “cured product of the ink composition” refers to a product obtained by curing the curable component in the ink composition (the ink composition after drying when the ink composition contains a solvent component). This is the resulting cured product. In addition, the cured product of the dried ink composition may not contain a solvent component.

[Photopolymerizable compound]
A photopolymerizable compound is a compound that polymerizes by irradiation with light, and is, for example, a radical photopolymerizable compound or a cationic photopolymerizable compound. The photopolymerizable compound may be either a photopolymerizable monomer or a photopolymerizable oligomer (hereinafter collectively referred to as "photopolymerizable monomer").
These photopolymerizable compounds are preferably used together with a photoinitiator. A radical photopolymerizable compound is used together with a radical photopolymerization initiator, and a cationic photopolymerizable compound is used together with a cationic photopolymerization initiator. In other words, the photopolymerizable compound can contain a photopolymerizable compound and a photoinitiator.
As the photopolymerizable compound, a photoradical polymerizable compound and a photocationically polymerizable compound may be used in combination, or a compound having both photoradical polymerizability and photocationic polymerizability may be used. As the photopolymerization initiator, a radical photopolymerization initiator and a cationic photopolymerization initiator may be used in combination.

Examples of photoradically polymerizable compounds include monomers having an ethylenically unsaturated group (hereinafter also referred to as "ethylenically unsaturated monomers"), monomers having an isocyanate group, and the like.
Here, the ethylenically unsaturated monomer means a monomer having an ethylenically unsaturated bond (carbon-carbon double bond). Examples of ethylenically unsaturated monomers include monomers having ethylenically unsaturated groups such as vinyl groups, vinylene groups, and vinylidene groups. Monomers having these groups are sometimes referred to as "vinyl monomers".

The number of ethylenically unsaturated bonds (for example, the number of ethylenically unsaturated groups) in the ethylenically unsaturated monomer is preferably 1-3. An ethylenically unsaturated monomer may be used individually by 1 type, or may use 2 or more types together.
Ethylenically unsaturated monomers are a monomer having one or two ethylenically unsaturated groups and ethylene and monomers having two or three polyunsaturated groups. That is, the ethylenically unsaturated monomer is at least selected from the group consisting of a combination of a monofunctional monomer and a bifunctional monomer, a combination of a monofunctional monomer and a trifunctional monomer, and a combination of a bifunctional monomer and a trifunctional monomer. It can be a combination.

Examples of ethylenically unsaturated groups include vinyl, vinylene and vinylidene groups, as well as (meth)acryloyl groups. In this specification, "(meth)acrylate" means "acrylate" and "methacrylate" corresponding thereto. The same applies to expressions such as "(meth)acrylamide" and "(meth)acryloyl".
The photopolymerizable compound preferably contains a compound having a (meth)acryloyl group as an ethylenically unsaturated group, more preferably (meth)acrylate and (meth)acrylamide.

Examples of monofunctional monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) Acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, phenoxyethyl (meth)acrylate ) acrylate, nonylphenoxyethyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) ) acrylate, benzyl (meth)acrylate, phenylbenzyl (meth)acrylate, mono(2-acryloyloxyethyl) succinate, mono(2-methacryloyloxyethyl) succinate, N-[2-(acryloyloxy)ethyl]phthalimide , N-[2-(acryloyloxy)ethyl]tetrahydrophthalimide, 4-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate (meth)acrylates;

(Meth)acrylamide, N-isopropyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, diacetone (meth)acrylamide, 4-acryloylmorpholine, Nt-butyl ( meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, Nt-octyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-phenyl(meth)acrylamide, N - (meth)acrylamide such as dodecyl (meth)acrylamide;
Among these, linear aliphatic (meth)acrylates such as dodecyl (meth)acrylate, aromatic (meth)acrylates such as phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, Alicyclic (meth)acrylates such as dicyclopentenyl (meth)acrylate and dicyclopentenyloxyethyl (meth)acrylate are preferably used.

Monomers having two ethylenically unsaturated groups (bifunctional monomers) include, for example, 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol Di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,8-octanediol di(meth)acrylate (Meth) acrylate, 1,9-nonanediol di(meth) acrylate, tricyclodecanedimethanol di(meth) acrylate, ethoxylated (2) neopentyl glycol di(meth) acrylate [neopentyl glycol ethylene oxide 2 mol adduct compound obtained by diacrylate], propoxylated (2) glycol (meth)acrylate such as neopentyl glycol di(meth)acrylate [compound obtained by diacrylate of 2 mol of neopentyl glycol propylene oxide adduct];

Ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, di Alkylene glycol (meth)acrylates such as propylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, bis(4-acryloxypolyethoxyphenyl)propane;
neopentyl glycol hydroxypivalic acid ester diacrylate, di(meth)acrylate in which two hydroxyl groups of tris(2-hydroxyethyl)isocyanurate are substituted with (meth)acryloyloxy groups,
a di(meth)acrylate obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol, and two hydroxyl groups of the diol are substituted with (meth)acryloyloxy groups;
modified bisphenol A di(meth)acrylate, propylene oxide (PO) adduct di(meth)acrylate of bisphenol A, ethylene oxide (EO) adduct di(meth)acrylate of bisphenol A,

Di(meth)acrylate in which two hydroxyl groups of triol obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane are substituted with (meth)acryloyloxy groups, 4 mol or more per 1 mol of bisphenol A Di (meth) acrylate such as di (meth) acrylate in which two hydroxyl groups of the diol obtained by addition of ethylene oxide or propylene oxide are substituted by (meth) acryloyloxy groups;
Bis(meth)acrylamides such as N,N'-methylenebis(meth)acrylamide, N,N'-ethylenebis(meth)acrylamide; methyl 2-(allyloxymethyl)acrylate, diallyl phthalate, 1,3-diallyl oxy-2-propanol and the like.
Among these, straight-chain or branched alkylene ether di(meth)acrylates such as dipropylene glycol di(meth)acrylate, straight-chain di(meth)acrylates such as 1,4-butanediol di(meth)acrylate and 1,6-hexanediol diacrylate. Allyl ether compounds such as chain or branched aliphatic di(meth)acrylates and methyl 2-(allyloxymethyl)acrylate are preferably used.

Specific examples of monomers having three ethylenically unsaturated groups (trifunctional monomers) include glycerin tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and ethylene oxide-modified trimethylol. Propane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate and the like.

Examples of photo-cationically polymerizable compounds include epoxy compounds, oxetane compounds, and vinyl ether compounds.

Examples of epoxy compounds include aliphatic epoxy compounds such as bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, phenol novolac type epoxy compounds, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl ether, 1,2-epoxy- Alicyclic epoxy compounds such as 4-vinylcyclohexane, 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane, and the like.
A commercially available epoxy compound can also be used, and examples thereof include "Celoxide 2000", "Celoxide 3000", and "Celoxide 4000" manufactured by Daicel Chemical Industries, Ltd.

Examples of cationic polymerizable oxetane compounds include 2-ethylhexyloxetane, 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3 -n-butyloxetane, 3-hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl -3-propyloxetane, 3-hydroxyethyl-3-phenyloxetane, 3-hydroxypropyl-3-methyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl -3-phenyloxetane, 3-hydroxybutyl-3-methyloxetane and the like.

It is also possible to use a commercial item as an oxetane compound. Commercially available oxetane compounds include, for example, the Aron oxetane series manufactured by Toagosei Co., Ltd. ("OXT-101", "OXT-212", "OXT-121", "OXT-221", etc.); Daicel Chemical Industries, Ltd. "Celoxide 2021", "Celoxide 2021A", "Celoxide 2021P", "Celoxide 2080", "Celoxide 2081", "Celoxide 2083", "Celoxide 2085", "Epolead GT300", "Epolead GT301", "Epolead" manufactured by the company GT302", "Epolead GT400", "Epolead GT401" and "Epolead GT403"; "Cyracure UVR-6105", "Cyracure UVR-6107", "Cyracure UVR-6110", "Cyracure UVR" manufactured by Dow Chemical Japan Co., Ltd. -6128”, “ERL4289” and “ERL4299”, etc. can be used. In addition, known oxetane compounds (eg, oxetane compounds described in JP-A-2009-40830, etc.) can also be used.

Vinyl ether compounds include 2-hydroxyethyl vinyl ether, triethylene glycol vinyl monoether, tetraethylene glycol divinyl ether, trimethylolpropane trivinyl ether and the like.
Further, as photopolymerizable compounds, N-vinyl-ε-caprolactam, N-vinylpyrrolidone, N-vinylimidazole, N-vinylcarbazole, N-vinylmorpholine, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinyl compounds having a nitrogen atom and a vinyl group directly bonded to the nitrogen atom, such as N-vinylformamide and N-vinyl-5-methyl-2-oxazolidinone, and paragraph 0042 of JP-A-2013-182215. The photopolymerizable compounds described in 1 to 0049 can also be used.

The photopolymerizable compound is preferably alkali-insoluble from the viewpoint of easily obtaining a highly reliable pixel portion (cured product of the ink composition).
Here, in this specification, the photopolymerizable compound being alkali-insoluble means that the amount of the photopolymerizable compound dissolved in a 1% by mass aqueous potassium hydroxide solution at 25° C. is based on the total mass of the photopolymerizable compound. As, it means that it is 30% by mass or less.
The dissolved amount of the photopolymerizable compound is preferably 10% by mass or less, more preferably 3% by mass or less.

The content of the photopolymerizable compound in the ink composition enhances the dispersion stability of the luminescent nanoparticle composite, from the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink, from the viewpoint of improving the curability of the ink composition, From the standpoint of facilitating the production of a pixel portion with excellent shape stability and from the standpoint of improving the solvent resistance and abrasion resistance of the pixel portion (cured product of the ink composition), the total amount of components other than the organic solvent is 100 parts by mass. On the other hand, it is preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more.
The content of the photopolymerizable compound is a total of 100 parts by mass of components other than the organic solvent, from the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink and from the viewpoint of obtaining better light emission characteristics (e.g., external quantum efficiency). is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less.

[Photoinitiator]
The photopolymerization initiator is, for example, a radical photopolymerization initiator or a cationic photopolymerization initiator.
As the photoradical polymerization initiator, a molecular cleavage type or hydrogen abstraction type photoradical polymerization initiator is suitable.

Molecular cleavage type photoradical polymerization initiators include, for example, benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino -1-(4-morpholinophenyl)-butan-1-one, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine Oxide and the like can be preferably used.
Other molecular cleavage type radical photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone, benzoin ethyl ether, benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4 -isopropylphenyl)-2-hydroxy-2-methylpropan-1-one and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one may be used in combination.

Hydrogen abstraction type photoradical polymerization initiators include, for example, benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4′-methyl-diphenylsulfide and the like.
As the photopolymerization initiator, a molecular cleavage type photoradical polymerization initiator and a hydrogen abstraction type photoradical polymerization initiator may be used in combination.

Commercially available photopolymerization initiators can also be used, for example, sulfonium salt photocationic polymerization initiators such as "CPI-100P" manufactured by San-Apro, acyl such as "Lucirin TPO" manufactured by BASF. phosphine oxide compounds, BASF "Irgacure 907", "Irgacure 819", "Irgacure 379EG", "Irgacure 184" and "Irgacure PAG290";

From the viewpoint of the curability of the ink composition, the content of the photopolymerization initiator in the ink composition is preferably 0.1 parts by mass or more and 0.5 parts by mass with respect to 100 parts by mass of the photopolymerizable compound. It is more preferably 1 part by mass or more, further preferably 1 part by mass or more, and particularly preferably 3 parts by mass or more.
The content of the photopolymerization initiator is preferably 40 parts by mass or less and 30 parts by mass with respect to 100 parts by mass of the photopolymerizable compound, from the viewpoint of the temporal stability of the pixel portion (cured product of the ink composition). parts by mass or less, more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less.

In the present ink composition, the photopolymerization initiator may be used in combination with the polymerization accelerator.
Examples of polymerization accelerators include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, 4,4 '-Bis(diethylamino)benzophenone and other amines having no reactivity with photopolymerizable compounds can be mentioned. When a polymerization accelerator is used, its content is preferably in the range of 1 to 100% by mass with respect to the total amount of the photopolymerization initiator and polymerization accelerator.

[Antioxidant]
The ink composition may further contain an antioxidant. The antioxidant is a compound having a function of imparting excellent external quantum efficiency maintenance performance to the pixel portion.
The antioxidant is not particularly limited, and examples thereof include phenol antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, and the like. Among them, phenolic antioxidants and phosphorus antioxidants are preferred. These antioxidants may be used alone or in combination of two or more.

Phenolic antioxidants are also commonly referred to as hindered phenolic compounds.
Such phenolic antioxidants include, for example, pentaerythritol tetrakis[3-[3,5-di(t-butyl)-4-hydroxyphenyl]propionate], 2,6-di-t-butyl-p-cresol , 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-di-t-butyl-4-hydroxyphenyl)-propionate, distearyl (3,5-di-t-butyl-4-hydroxy benzyl)phosphonate, thiodiethylene glycol bis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl) ) propionate], 1,6-hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionamide], 4,4′-thiobis(6-t-butyl-m-cresol) , 2,2′-methylenebis(4-methyl-6-t-butylphenol), 2,2′-methylenebis(4-ethyl-6-t-butylphenol), bis[3,3-bis(4-hydroxy-3 -t-butylphenyl)butyric acid]glycol ester, 4,4′-butylidenebis(6-t-butyl-m-cresol), 2,2′-ethylidenebis(4,6-di-t-butylphenol), 2,2′-ethylidenebis(4-sec-butyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, bis[2- t-butyl-4-methyl-6-(2-hydroxy-3-t-butyl-5-methylbenzyl)phenyl]terephthalate, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4- t-butylbenzyl)isocyanurate, 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(3,5-di- t-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxyethyl]isocyanurate, Tetrakis[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane, 2-t-butyl-4-methyl-6-(2-acryloyloxy-3-t -butyl-5-methylbenzyl)phenol, 3,9-bis[1,1-dimethyl Tyl-2-{(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, triethylene glycol bis[ (3-t-butyl-4-hydroxy-5-methylphenyl)propionate] and the like.
Among them, pentaerythritol tetrakis[3-[3,5-di(t-butyl)-4-hydroxyphenyl]propionate] is preferable as the phenolic antioxidant because of its excellent solubility in the ink composition.

As the phosphorus antioxidant, a phosphite triester compound is preferred.
A phosphite triester compound is, for example, a compound represented by the formula: P(OR ⁵¹ )(OR ⁵² )(OR ⁵³ ). In the formula, R ⁵¹ , R ⁵² and R ⁵³ each independently represent a monovalent organic group. Also, two of R ⁵¹ , R ⁵² and R ⁵³ may combine with each other to form a ring structure.
A monovalent organic group sufficiently satisfies performance such as affinity with other components in the ink composition such as a photopolymerizable compound, and from the viewpoint of maintaining excellent external quantum efficiency of the pixel portion, A monovalent hydrocarbon group is preferred.
Examples of monovalent hydrocarbon groups include alkyl groups, aryl groups, and alkenyl groups. The number of carbon atoms in the monovalent hydrocarbon group is preferably 1 to 30, more preferably 4 to 18 from the viewpoint of solubility in the ink composition.

Alkyl groups may be straight or branched. Examples of alkyl groups include 2-ethylhexyl group, butyl group, octyl group, nonyl group, decyl group, isodecyl group, dodecyl group, hexadecyl group, octadecyl group and the like.
Examples of aryl groups include phenyl, naphthyl, t-butylphenyl, di-t-butylphenyl, octylphenyl, nonylphenyl, isodecylphenyl, isodecylphenyl, and isodecylnaphthyl groups. are mentioned.
The monovalent hydrocarbon group is preferably an alkyl group or an aryl group, more preferably an alkyl group or a phenyl group, from the viewpoint of maintaining excellent external quantum efficiency of the pixel portion.

At least two of R ⁵¹ , R ⁵² and R ⁵³ are preferably identical to each other. At least one of R ⁵¹ , R ⁵² and R ⁵³ is preferably a phenyl group, more preferably at least two are phenyl groups.
At least one of R ⁵¹ , R ⁵² and R ⁵³ is preferably a phenyl group, and one is preferably an alkyl group (particularly a branched alkyl group). That is, the phosphite triester compound preferably has at least one phenyl group and one alkyl group.
When the phosphite triester compound has the above functional group, it sufficiently satisfies performance such as affinity with other components in the ink composition, such as the photopolymerizable compound, and reduces the external quantum efficiency of the pixel portion. can be suppressed.

Examples of the compound represented by the above formula include triphenylphosphite, 2-ethylhexyldiphenylphosphite, diphenyloctylphosphite and the like.
The phosphite triester compound may be either liquid or solid at room temperature (25° C.), but it may not be compatible with other components in the ink composition, such as photopolymerizable compounds. It is preferably liquid at room temperature (25° C.) from the viewpoint of sufficiently satisfying the above performance and being able to suppress a decrease in the external quantum efficiency of the pixel portion.
The melting point of the phosphite triester compound is preferably 20° C. or lower, more preferably 10° C. or lower.

The content of the antioxidant in the ink composition is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the photopolymerizable compound, from the viewpoint of suppressing a decrease in the external quantum efficiency of the pixel portion. It is more preferably 0.1 parts by mass or more, still more preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more, and most preferably 2 parts by mass or more.
Even if the antioxidant is added in a small amount, it is possible to effectively suppress the deterioration of the external quantum efficiency of the pixel portion. Therefore, the content of the antioxidant is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and 5 parts by mass or less with respect to 100 parts by mass of the photopolymerizable compound. is more preferred.

[Light scattering particles]
The ink composition may further contain light scattering particles. Light-scattering particles are, for example, optically inactive inorganic particles. When the ink composition contains light-scattering particles, it is possible to scatter the light emitted from the light source with which the pixel portion is irradiated, so excellent optical properties (eg, external quantum efficiency) can be obtained.

Materials constituting the light-scattering particles include single metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, platinum and gold; silicon oxide, talc, clay, kaolin and alumina. White, oxides such as titanium oxide, magnesium oxide, barium oxide, aluminum oxide, bismuth oxide, zirconium oxide, zinc oxide; carbonates such as magnesium carbonate, barium carbonate, bismuth subcarbonate, calcium carbonate; complex oxides such as barium zirconate, calcium zirconate, calcium titanate, barium titanate and strontium titanate; metal salts such as barium sulfate and bismuth subnitrate.

The light-scattering particles are titanium oxide, aluminum oxide, zirconium oxide, zinc oxide, calcium carbonate, and barium sulfate, from the viewpoint of excellent ejection stability of the ink composition (inkjet ink) and from the viewpoint of improving the external quantum efficiency. , barium titanate and silicon oxide, preferably at least one selected from the group consisting of titanium oxide, zirconium oxide, zinc oxide and barium titanate. preferable.

Examples of the shape of the light-scattering particles include spherical, filamentary, and irregular shapes. However, the shape of the light-scattering particles is preferably a shape with less directivity (for example, a spherical shape, a regular tetrahedral shape, etc.). By using light-scattering particles having such a shape, the uniformity, fluidity and light-scattering properties of the ink composition can be further improved, and excellent ejection stability can be ensured.

The average particle diameter (volume average diameter) of the light-scattering particles is preferably 0.05 μm or more, and preferably 0.2 μm, from the viewpoint of excellent ejection stability of the ink composition and excellent effect of improving the external quantum efficiency. It is more preferably 0.3 μm or more, and further preferably 0.3 μm or more.
From the viewpoint of excellent ejection stability of the ink composition, the average particle size of the light-scattering particles is preferably 1 μm or less, more preferably 0.6 μm or less, and further preferably 0.4 μm or less. preferable.

The average particle size of the light scattering particles is 0.05 to 1 μm, 0.05 to 0.6 μm, 0.05 to 0.4 μm, 0.2 to 1 μm, 0.2 to 0.6 μm, 0.2 to It is preferably 0.4 μm, 0.3-1 μm, 0.3-0.6 μm or 0.3-0.4 μm.
In the present specification, the average particle diameter of the light scattering particles is obtained by measuring with a dynamic light scattering Nanotrack particle size distribution meter and calculating the volume average diameter.
The average particle size of the light-scattering particles to be used can be obtained, for example, by measuring the particle size of each particle with a transmission electron microscope or scanning electron microscope and calculating the volume average size.

The content of the light-scattering particles in the ink composition is 0.1 with respect to a total of 100 parts by mass of the components other than the organic solvent contained in the ink composition, from the viewpoint of improving the external quantum efficiency of the pixel portion. It is preferably at least 1 part by mass, more preferably at least 1 part by mass, and even more preferably at least 3 parts by mass.
The content of the light-scattering particles is 100 parts by mass in total for the components other than the organic solvent contained in the ink composition, from the viewpoint of excellent ejection stability of the ink composition and from the viewpoint of improving the external quantum efficiency of the pixel portion. is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

The mass ratio of the content of the light-scattering particles to the content of the luminescent nanoparticle composite (light-scattering particles/luminescent nanoparticle composite) is 0 from the viewpoint of improving the external quantum efficiency of the pixel portion. It is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.5 or more.
The mass ratio (light-scattering particle/luminescent nanoparticle composite) is 5 or less from the viewpoint of excellent effect of improving the external quantum efficiency of the pixel portion and excellent continuous ejection property (ejection stability) in the inkjet method. It is preferably 1.5, more preferably 2 or less, and even more preferably 1.5 or less.

The total amount of the luminescent nanoparticle composite and the light-scattering particles in the ink composition is 100 parts by mass of the components other than the organic solvent contained in the ink composition, from the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink. is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more.
The total amount of the luminescent nanoparticle composite and the light-scattering particles in the ink composition is 100 parts by mass of the components other than the organic solvent contained in the ink composition, from the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink. is preferably 75 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 55 parts by mass or less.

[Polymer dispersant]
The ink composition may further contain a polymeric dispersant. The polymeric dispersant is preferably a polymeric compound having a weight-average molecular weight of 750 or more and having a functional group having affinity for the light-scattering particles.
The polymeric dispersant has a function of stably dispersing the light-scattering particles in the ink composition. The polymer dispersant adsorbs to the light-scattering particles via a functional group that has an affinity for the light-scattering particles, and electrostatic repulsion and/or steric repulsion between the polymer dispersants causes light-scattering properties. The particles are dispersed in the ink composition.

When the ink composition contains a polymer dispersant, even when the content of the light-scattering particles is relatively large (for example, about 60% by mass), the light-scattering particles are well dispersed. can be made
The polymeric dispersant is preferably bound to the surface of the light-scattering particles. However, the polymer dispersant may be bound to the surface of the luminescent nanoparticle composite, or may be free in the ink composition.
Functional groups that have an affinity for light scattering particles include acidic functional groups, basic functional groups and nonionic functional groups. Acidic functional groups have dissociative protons and may be neutralized with bases such as amines and hydroxide ions, while basic functional groups are neutralized with acids such as organic acids and inorganic acids. It may be neutralized.

Examples of acidic functional groups include a carboxy group (--COOH), a sulfo group (--SO ₃ H), a sulfate group (--OSO ₃ H), a phosphonic acid group (--PO(OH) ₃ ), a phosphate group (--OPO ( OH) ₃ ), phosphinic acid group (--PO(OH)--), mercapto group (--SH) and the like.
Basic functional groups include primary, secondary and tertiary amino groups, ammonium groups, imino groups, and nitrogen-containing heterocyclic groups such as pyridine, pyrimidine, pyrazine, imidazole and triazole.
Nonionic functional groups include hydroxy group, ether group, thioether group, sulfinyl group (-SO-), sulfonyl group ( _-SO2- ), carbonyl group, formyl group, ester group, carbonate group, amide group, Carbamoyl group, ureido group, thioamide group, thioureido group, sulfamoyl group, cyano group, alkenyl group, alkynyl group, phosphine oxide group, phosphine sulfide group and the like.

The polymeric dispersant may be a polymer (homopolymer) of a single monomer, or a copolymer (copolymer) of a plurality of types of monomers.
Further, the polymeric dispersant may be any of random copolymers, block copolymers and graft copolymers. When the polymeric dispersant is a graft copolymer, it may be a comb-shaped graft copolymer or a star-shaped graft copolymer.
Examples of polymer dispersants include acrylic resins, polyester resins, polyurethane resins, polyamide resins, polyethers, phenol resins, silicone resins, polyurea resins, amino resins, epoxy resins, polyamines such as polyethyleneimine and polyallylamine, and polyimides. etc.

A commercial item can also be used for a polymeric dispersing agent. Commercially available polymer dispersants include, for example, Ajinomoto Fine-Techno Co., Ltd. Ajisper PB series, BYK DISPER BYK series, BASF Efka series, and the like.

[Zinc compound]
The ink composition may further contain a zinc compound having zinc as a central metal and two ligands coordinated to the zinc. The number of zinc atoms in such a zinc compound is one, and the valence of zinc is preferably bivalent. When such a zinc compound is further contained, the wavelength shift of the converted light in the pixel portion (the phenomenon in which the wavelength of the converted light emitted from the pixel portion shifts to a longer wavelength side than the emission wavelength of the luminescent nanoparticle composite) can be reduced. .

In this zinc compound, the two ligands each have a sulfur atom, and the sulfur atom is coordinated to zinc by direct bonding (eg, ionic bonding) to zinc. The two ligands may be the same or different from each other.
The zinc compound preferably has a molecular weight of 700 or less. When the molecular weight of the zinc compound is 700 or less, the effect of reducing wavelength shift tends to be more pronounced, and the initial external quantum efficiency and photostability of the pixel portion tend to be more excellent. The molecular weight of the zinc compound may be 600 or less, or 500 or less. Moreover, the molecular weight of the zinc compound may be 200 or more from the viewpoint of easily increasing the solubility in the ink composition and from the viewpoint of easily obtaining the effect of reducing the wavelength shift.

The ligand is preferably a compound having a coordinating functional group having a sulfur atom. Such ligands are coordinated to zinc by directly bonding the sulfur atom of the coordinating functional group to the zinc. Examples of coordinating functional groups include thiol groups (mercapto groups), dithiocarbamic acid groups, dithiocarboxylic acid groups, thiocarboxylic acid groups, and the like.
These coordinating functional groups are, for example, deprotonated to bind zinc. That is, the ligand may coordinate to the zinc in an ionized state.

Examples of compounds having a coordinating functional group include dithiocarbamic acids such as monoalkyldithiocarbamic acid, dialkyldithiocarbamic acid, diaryldithiocarbamic acid, alkylaryldithiocarbamic acid, and dialkyldithiocarbamic acid; mercaptopyridines such as 2-mercaptopyridine N-oxide; mercaptobenzothiazoles such as 2-mercaptobenzothiazole, mercaptobenzoxazoles such as 2-mercaptobenzoxazole, and the like. From the viewpoint of further improving the external quantum efficiency, the viewpoint of further improving the photostability, and the viewpoint of obtaining a more pronounced effect of reducing the wavelength shift, at least one of the two ligands is a dithiocarbamic acid (coordinating functional a compound having a dithiocarbamic acid group as a group), and both of the two ligands are more preferably dithiocarbamic acids (compounds having a dithiocarbamic acid group as a coordinating functional group).

Specific examples of zinc compounds include zinc bis(2-hydroxyethyl)dithiocarbamate, zinc bis(2-mercaptopyridine N-oxide), zinc (toluene-3,4-dithiolato), and zinc bis(dibenzyldithiocarbamate). , bis(dibutyldithiocarbamate)zinc, bis(diethyldithiocarbamate)zinc, bis(N-ethyl-N-phenyldithiocarbamate)zinc, bis(2-mercaptobenzothiazole)zinc and the like.
Commercially available products can also be used, and examples thereof include "Noxeller BZ" (trade name) manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., "Zinc Pyrithione" manufactured by Tokyo Chemical Industry Co., Ltd., and the like.

From the viewpoint of further improving the external quantum efficiency, the viewpoint of further improving the photostability, and the viewpoint of obtaining a more remarkable effect of reducing the wavelength shift, the content of the zinc compound is the component other than the organic solvent contained in the ink composition. It is preferably 0.1 part by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to the total 100 parts by mass of the above.
From the same viewpoint, the content of the zinc compound is preferably 20 parts by mass or less, and 10 parts by mass or less, with respect to the total 100 parts by mass of the components other than the organic solvent contained in the ink composition. is more preferably 7 parts by mass or less.

[Organic solvent]
The ink composition may further contain an organic solvent, if necessary.
Examples of organic solvents include ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol dibutyl ether, diethyl adipate, dibutyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, and succinic acid. diethyl, 1,4-butanediol diacetate, glyceryl triacetate and the like.

The boiling point of the organic solvent is preferably 150° C. or higher, more preferably 180° C. or higher, from the viewpoint of continuous ejection stability of the ink composition (inkjet ink).
Further, since it is necessary to remove the organic solvent from the ink composition before curing the ink composition when forming the pixel portion, the boiling point of the organic solvent is preferably 300° C. or less from the viewpoint of easy removal of the organic solvent. preferable.

The organic solvent preferably contains an acetate compound having a boiling point of 150° C. or higher. In this case, the affinity between the luminescent nanoparticle composite and the organic solvent is further improved, and the luminescent nanoparticle composite can exhibit excellent luminous properties.
Specific examples of such acetate compounds include monoacetate compounds such as diethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol methyl ether acetate, 1,4- Diacetate compounds such as butanediol diacetate and propylene glycol diacetate, glyceryl triacetate and the like can be mentioned.

In the ink composition of the present embodiment, since the photopolymerizable compound also functions as a dispersion medium, it is possible to disperse the light-scattering particles and the luminescent nanoparticle composite without solvent. In this case, there is an advantage that the step of removing the organic solvent by drying is not required when forming the pixel portion.

The ink composition may further contain additives other than the components described above, such as UV absorbers, surface tension modifiers, anti-fading agents, conductive salts, etc., as long as the effects of the present invention are not impaired. good.

From the viewpoint of ejection stability, the ink composition may have a viscosity of 2 mPa·s or more, 5 mPa·s or more, or 7 mPa·s or more. The viscosity during ejection may be 20 mPa·s or less, 15 mPa·s or less, or 12 mPa·s or less.
The viscosity of the ink composition during ejection is 2 to 20 mPa·s, 2 to 15 mPa·s, 2 to 12 mPa·s, 5 to 20 mPa·s, 5 to 15 mPa·s, 5 to 12 mPa·s, and 7 to 20 mPa·s. s, 7 to 15 mPa·s or 7 to 12 mPa·s.
In this specification, the viscosity of the ink composition at the time of ejection is a value measured using an E-type viscometer at the same temperature as at the time of ejection.

When the viscosity of the ink composition during ejection is 2 mPa·s or more, the meniscus shape of the ink composition at the tip of the ink ejection hole of the ejection head is stabilized. timing control) becomes easier.
On the other hand, when the ink composition has a viscosity of 20 mPa·s or less during ejection, the ink composition can be smoothly ejected from the ink ejection holes.

The surface tension of the ink composition is preferably a surface tension suitable for inkjet inks, specifically preferably 20 to 40 mN/m, more preferably 25 to 35 mN/m. By adjusting the surface tension to such a range, it is possible to facilitate ejection control of the ink composition (for example, control of the ejection amount and ejection timing) and to suppress the occurrence of flight deflection.
The term "flight deflection" means that when the ink composition is ejected from the ink ejection holes, the landing position of the ink composition deviates from the target position by 30 μm or more.

When the surface tension is 40 mN/m or less, the meniscus shape of the ink composition at the tip of the ink ejection hole is stabilized, so that the ejection control of the ink composition (for example, control of ejection amount and ejection timing) becomes easy. .
On the other hand, when the surface tension is 20 mN/m or more, it is possible to prevent the periphery of the ink ejection hole from being contaminated with the ink composition, so that the occurrence of flight deflection can be suppressed. That is, the ink composition does not land accurately in the formation region of the pixel portion to be landed, and a pixel portion is insufficiently filled with the ink composition, or a pixel portion formation region adjacent to the pixel portion formation region to be landed (or It is possible to prevent the ink composition from landing on the pixel portion) and lowering the color reproducibility.
In the specification of the present application, the surface tension of the ink composition is a value measured at 23° C. using the ring method (also referred to as ring ring method).

When the ink composition of the present embodiment is used as an inkjet ink, it is preferably applied to a piezo-type inkjet recording apparatus. In the piezo method, the ink composition is not instantaneously exposed to high temperatures during ejection. Therefore, deterioration of the luminescent nanoparticle composite is less likely to occur, and desired light emission characteristics can be easily obtained in the pixel portion (light conversion layer).
Although one embodiment of the ink composition has been described above, the ink composition of the embodiment described above can also be used in, for example, a photolithography method in addition to the inkjet method. In this case, the ink composition preferably contains an alkali-soluble resin as a binder polymer.

When the ink composition is used in photolithography, first, the ink composition is applied onto a substrate, and the ink composition is dried to form a coating film. The obtained coating film is soluble in an alkaline developer, and is patterned by being treated with an alkaline developer. At this time, since an aqueous solution is preferably used as the alkaline developer from the viewpoint of easiness of waste liquid treatment, the coated film of the ink composition is treated with an aqueous solution.
On the other hand, in the case of ink compositions using luminescent nanoparticle complexes (quantum dots, etc.), the luminescent nanoparticle complexes are unstable against water, and the luminescent properties (e.g., fluorescence properties) are impaired by moisture. There is a risk that The ink composition of the present invention is preferably used in an ink-jet method that does not require treatment with an alkaline developer (aqueous solution).

Further, even when the coating film of the ink composition is not treated with an alkaline developer, if the ink composition is alkali-soluble, the coating film of the ink composition easily absorbs moisture in the atmosphere. There is a risk that the luminescence properties (for example, fluorescence properties) of the luminescent nanoparticle composite (quantum dot, etc.) may deteriorate over time.
In the present embodiment, the coating film of the ink composition is preferably alkali-insoluble from the viewpoint of more reliably reducing the occurrence of problems due to water absorption. That is, the ink composition of the present embodiment is preferably an ink composition capable of forming an alkali-insoluble coating film.

Such an ink composition can be obtained by using an alkali-insoluble photopolymerizable compound as the photopolymerizable compound.
Here, the fact that the coating film of the ink composition is alkali-insoluble means that the amount of dissolution of the coating film of the ink composition in a 1% by mass aqueous solution of potassium hydroxide at 25° C. is the total mass of the coating film of the ink composition. As a standard, it means 30% by mass or less. The dissolved amount is preferably 10% by mass or less, more preferably 3% by mass or less.
It should be noted that the fact that the ink composition is an ink composition capable of forming an alkali-insoluble coating film means that the thickness obtained by applying the ink composition on a substrate and then drying it under the conditions of 80 ° C. and 3 minutes It can be confirmed by measuring the amount of dissolution of the coating film of 1 μm.

<Method for producing ink composition>
The ink composition of the present embodiment includes, for example, a step of mixing the above-described components (the luminescent nanoparticle composite, the photopolymerizable compound, and other optional components).
The method for producing the ink composition may further include a step of dispersing the mixture of the above components.
As an example, a method for producing an ink composition containing light-scattering particles will be described below.

A method for producing an ink composition containing light-scattering particles includes, for example, a first step of preparing a dispersion of light-scattering particles, and mixing the dispersion of light-scattering particles and a luminescent nanoparticle composite. and a second step.
The dispersion of light scattering particles may further contain a polymeric dispersant. In this method, the dispersion of light-scattering particles may further contain a photopolymerizable compound, and the photopolymerizable compound may be further mixed in the second step.
According to the above method, the light-scattering particles can be sufficiently dispersed. Therefore, it is possible to improve the optical properties (for example, external quantum efficiency) of the pixel portion, and to easily obtain an ink composition having excellent ejection stability.

In the first step, light-scattering particles may be mixed with, if necessary, a polymer dispersant and a photopolymerizable compound, and subjected to dispersion treatment to prepare a dispersion of light-scattering particles. good.
Mixing and dispersing treatments can be carried out using dispersing devices such as, for example, bead mills, paint conditioners, planetary stirrers, jet mills, and the like. It is preferable to use a bead mill or a paint conditioner from the viewpoint of improving the dispersibility of the light-scattering particles and facilitating adjustment of the average particle size of the light-scattering particles to a desired range.
Further, by mixing the light-scattering particles and the polymer dispersant before mixing the luminescent nanoparticle composite and the light-scattering particles, the light-scattering particles can be dispersed more sufficiently. Therefore, excellent ejection stability and excellent external quantum efficiency can be obtained more easily.

The method for producing the ink composition may further include, before the second step, a step of preparing a dispersion of the luminescent nanoparticle composites containing the luminescent nanoparticle composites and the photopolymerizable compound. good. In this case, in the second step, a dispersion of light-scattering particles and a dispersion of luminescent nanoparticle composites are mixed.
In the step of preparing the dispersion of the luminescent nanoparticle composites, the luminescent nanoparticle composites and the photopolymerizable compound are mixed and subjected to dispersion treatment to prepare the dispersion of the luminescent nanoparticle composites. you can

Mixing and dispersing treatments can be carried out using dispersing devices such as, for example, bead mills, paint conditioners, planetary stirrers, jet mills, and the like. It is preferable to use a bead mill, a paint conditioner, or a jet mill from the viewpoint of improving the dispersibility of the luminescent nanoparticle composite and facilitating adjustment of the average particle size of the luminescent nanoparticle composite to the desired range.
According to such a method, the luminescent nanoparticle composite can be sufficiently dispersed. Therefore, it is possible to improve the optical characteristics (for example, external quantum efficiency) of the pixel portion, and easily obtain an ink composition having excellent ejection stability.

In the above production method, when other components such as antioxidants and organic solvents are blended, these components may be mixed with the dispersion of the luminescent nanoparticle composites, and may be added to the dispersion of the light-scattering particles. They may be mixed, or may be mixed in a mixed dispersion obtained by mixing a dispersion of the luminescent nanoparticle composite and a dispersion of the light-scattering particles.

<Ink composition set>
An ink composition set of one embodiment includes the ink composition of the embodiment described above. The ink composition set may include an ink composition that does not contain a luminescent nanoparticle complex (non-luminescent ink composition) in addition to the ink composition (luminescent ink composition) of the above-described embodiment. good.
The non-luminescent ink composition is, for example, a conventionally known ink composition. The non-luminescent ink composition can have the same composition as the ink composition (luminescent ink composition) of the embodiment described above, except that it does not contain a luminescent nanoparticle complex.

A non-luminescent ink composition does not contain a luminescent nanoparticle composite. Therefore, when light is incident on a pixel portion formed of a non-luminescent ink composition (a pixel portion containing a cured product of the non-luminescent ink composition), the light emitted from the pixel portion is almost the same as the incident light. have the same wavelength.
Therefore, the non-luminous ink composition is preferably used to form a pixel portion having the same color as the light from the light source. For example, if the light from the light source has a wavelength in the range of 420 to 480 nm (blue light), the pixel portion formed with the non-luminescent ink composition can be a blue pixel portion.

The non-luminescent ink composition preferably contains light scattering particles. When the non-luminous ink composition contains light-scattering particles, incident light can be scattered in the pixel portions formed by the non-luminous ink composition. Thereby, the light intensity difference in the viewing angle of the light emitted from the pixel portion can be reduced.

<Light conversion layer and color filter>
Next, the details of the light conversion layer and the color filter obtained by using the ink composition set of the embodiment described above will be described with reference to the drawings. In the following description, the same reference numerals are used for the same or corresponding elements, and overlapping descriptions are omitted.
FIG. 1 is a schematic cross-sectional view of a color filter according to one embodiment of the invention. Hereinafter, for convenience of explanation, the upper side in FIG. 1 will also be referred to as "upper" or "upper", and the lower side will also be referred to as "lower" or "lower".
A color filter 100 shown in FIG. 1 has a substrate 40 and a light conversion layer 30 provided on the substrate 40 . The light conversion layer 30 includes a plurality of pixel portions 10 and a light shielding portion 20 .

The light conversion layer 30 has, as the pixel portions 10, a first pixel portion 10a, a second pixel portion 10b, and a third pixel portion 10c. The first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c are arranged in a lattice so as to repeat this order.
The light shielding portion 20 is provided between the adjacent pixel portions 10, 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 between the third pixel portion. 10c and the first pixel portion 10a. In other words, adjacent pixel portions 10 are separated by the light shielding portion 20 .

The first pixel portion 10a and the second pixel portion 10b are luminescent pixel portions (luminescent pixel portions) containing a luminescent nanoparticle composite, a curing component, and light-scattering particles. At least one of the first pixel portion 10a and the second pixel portion 10b contains the cured ink composition described above.
As shown in FIG. 1, the first pixel portion 10a includes a first curing component 13a, and a first luminescent nanoparticle composite 11a and first light-scattering particles 12a dispersed in the first curing component 13a. include. Similarly, the second pixel portion 10b includes a second curing component 13b, and second luminescent nanoparticle composites 11b and second light-scattering particles 12b dispersed in the second curing component 13b.

The curing component is a component obtained by polymerization of the photopolymerizable compound, and the polymer of the photopolymerizable compound and the organic components (polymer dispersant, unreacted photopolymerizable compound, etc.) in the ink composition may be included.
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. Also, the first light-scattering particles 12a and the second light-scattering particles 12b may be the same or different.

The first light-emitting nanoparticle composite 11a is a red-light-emitting nanoparticle composite that absorbs light in the wavelength range of 420 to 480 nm and emits light having an emission peak in the wavelength range of 605 to 665 nm. That is, the first pixel section 10a can be said to be a red pixel section for converting blue light into red light.
The second luminescent nanoparticle complex 11b is a green luminescent nanoparticle complex that absorbs light in the wavelength range of 420 to 480 nm and emits light having an emission peak in the wavelength range of 500 to 560 nm. That is, the second pixel section 10b can be said to be a green pixel section for converting blue light into green light.

The content of the luminescent nanoparticle composite in the luminescent pixel portion is based on the total weight of the cured luminescent ink composition, from the viewpoint of obtaining excellent luminescence intensity and excellent effect of improving the external quantum efficiency. , preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, particularly preferably 20% by mass or more, and 30% by mass or more is most preferred.
The content of the luminescent nanoparticle composite is 80% by mass or less based on the total mass of the cured luminescent ink composition, from the viewpoint of obtaining excellent reliability of the pixel portion and excellent emission intensity. It is preferably 75% by mass or less, more preferably 70% by mass or less, and particularly preferably 60% by mass or less.

The content of the light-scattering particles in the luminescent pixel portion is preferably 0.1% by mass or more based on the total mass of the cured luminescent ink composition, from the viewpoint of improving the external quantum efficiency. It is preferably 1% by mass or more, more preferably 3% by mass or more.
The content of the light-scattering particles is 60% by mass or less based on the total mass of the cured luminescent ink composition, from the viewpoint of improving the external quantum efficiency and the reliability of the pixel portion. is preferably 50% by mass or less, more preferably 40% by mass or less, 30% by mass or less, or 25% by mass or less, particularly preferably 20% by mass or less, and 15 % or less is most preferable.

The third pixel portion 10c is a non-luminous pixel portion (non-luminous pixel portion) containing a cured product of the non-luminous ink composition described above. The cured product does not contain the luminescent nanoparticle composite, but contains light-scattering particles and a curing component.
As shown in FIG. 1, the third pixel portion 10c includes a third curing component 13c and third light scattering particles 12c dispersed in the third curing component 13c.
The third curing component 13c is, for example, a component obtained by polymerization of a photopolymerizable compound, and includes a polymer of the photopolymerizable compound.
The third light scattering particles 12c may be the same as or different from the first light scattering particles 12a and the second light scattering particles 12b.

The third pixel section 10c preferably has a transmittance of 30% or more for light with a wavelength of 420 to 480 nm, for example. In this case, the third pixel section 10c can function as a blue pixel section by using a light source that emits light with a wavelength of 420 to 480 nm.
The transmittance of the third pixel section 10c can be measured with a microscopic spectrometer.

The content of the light-scattering particles in the third pixel portion (non-luminous pixel portion) 10c is based on the total mass of the cured non-luminous ink composition from the viewpoint of further reducing the difference in light intensity at the viewing angle. , preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more.
From the viewpoint of further reducing light reflection, the content of the light-scattering particles is preferably 80% by mass or less, and 75% by mass or less, based on the total mass of the cured non-luminescent ink composition. is more preferably 70% by mass or less.

The thickness of the pixel portion (the first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c) is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more. preferable.
The thickness of the pixel portion (the first pixel portion 10a, the second pixel portion 10b, and the second pixel portion 10c) is preferably 30 μm or less, more preferably 20 μm or less, and further preferably 15 μm or less. preferable.

The light shielding portion 20 is a partition portion (black matrix) provided for the purpose of separating adjacent pixel portions to prevent color mixture (crosstalk) and for the purpose of preventing leakage of light from the light source.
The constituent material of the light shielding portion 20 is not particularly limited, but in addition to metal such as chromium, a resin composition containing a binder resin and light shielding particles such as carbon fine particles, metal oxides, inorganic pigments, and organic pigments. is mentioned.
Binder resins include, for example, polyimide resins, acrylic resins, epoxy resins, polyacrylamides, polyvinyl alcohols, gelatin, casein, resins containing two or more of cellulose, photosensitive resins, O/W emulsion resins (e.g. , reactive silicone emulsion) and the like can be used.
The thickness of the light shielding portion 20 is preferably 1 to 30 μm.

The base material 40 is a transparent base material having optical transparency. For the substrate 40, for example, a transparent glass substrate made of quartz glass, Pyrex (registered trademark) glass, synthetic quartz, etc., a transparent resin film, a transparent flexible substrate such as an optical resin film, or the like is used. be able to. Above all, it is preferable to use a glass substrate made of alkali-free glass that does not contain an alkali component in the glass as the substrate 40 .
Specific examples of alkali-free glass include "7059 glass", "1737 glass", "Eagle 200" and "Eagle XG" manufactured by Corning, "AN100" manufactured by AGC, and "OA-10G" and "OA-11". These materials have a small coefficient of thermal expansion and are excellent in dimensional stability and workability in high-temperature heat treatment.

The color filter 100 having the light conversion layer 30 as described above can be suitably used in combination with a light source that emits light in the wavelength range of 420 to 480 nm.

For example, the color filter 100 is formed by forming the light shielding portions 20 in a pattern on the substrate 40 and then forming the pixel portions 10 in the pixel portion forming regions partitioned by the light shielding portions 20 on the substrate 40. can be manufactured.
The pixel portion 10 is formed by a step of selectively applying an ink composition (inkjet ink) to a pixel portion forming region on the substrate 40 by an inkjet method, and applying an active energy ray (for example, ultraviolet rays) to the ink composition. irradiating and curing the ink composition.
A luminescent pixel portion can be obtained by using the luminescent ink composition described above as the ink composition, and a non-luminescent pixel portion can be obtained by using a non-luminescent ink composition.

The light-shielding portion 20 can be formed in a region that serves as a boundary between a plurality of pixel portions on one surface of the substrate 40 by patterning a thin film of a metal such as chromium or a thin film of a resin composition containing light-shielding particles. can.
A metal thin film can be formed by, for example, a sputtering method, a vacuum deposition method, or the like. A thin film of a resin composition containing light-shielding particles can be formed by, for example, a method such as coating or printing.
As a method for patterning, a photolithography method or the like can be used.

Examples of the ink jet method include a bubble jet (registered trademark) method using an electrothermal transducer as an energy generating element, and a piezo jet method using a piezoelectric element.
When the ink composition contains an organic solvent, it is preferable to remove at least part of the organic solvent, more preferably all of the organic solvent, during drying.
The method for drying the ink composition is preferably drying under reduced pressure (reduced pressure drying). From the viewpoint of controlling the composition of the ink composition, the drying under reduced pressure is usually carried out under a pressure of 1.0 to 500 Pa at 20 to 30° C. for 3 to 30 minutes.

Curing of the ink composition can be performed using, for example, a mercury lamp, a metal halide lamp, a xenon lamp, an LED, or the like.
The wavelength of light for irradiation is preferably 200 to 440 nm, and the exposure dose is preferably 10 to 4000 mJ/cm ² .

In order to reduce outgassing by removing unreacted substances and improve adhesiveness by thermal crosslinking, the heating temperature is preferably 110 to 250° C. when heat treatment (post-baking) of the cured product is performed. The heating time is preferably 10 to 120 minutes.

Although one embodiment of the light conversion layer, the color filter, and the manufacturing method thereof has been described above, the present invention is not limited to these.
For example, the light conversion layer includes a pixel portion (blue pixel portion).
In addition, the light conversion layer includes a pixel portion (for example, a yellow pixel portion) containing a cured product of a luminescent ink composition containing a luminescent nanoparticle composite that emits light of a color other than red, green, and blue. may be provided. In this case, each of the luminescent nanoparticle composites contained in each pixel portion of the light conversion layer preferably has a maximum absorption wavelength within the same wavelength range.

Moreover, at least part of the pixel portion 10 of the light conversion layer 30 may include a cured product of a composition containing a pigment other than the luminescent nanoparticle composite.
Further, the color filter 100 may include an ink-repellent layer made of an ink-repellent material having a narrower width than the light-shielding portion 20 on the light-shielding portion 20 .
Furthermore, instead of providing an ink-repellent layer, a photocatalyst-containing layer as a variable wettability layer is formed in a solid manner in a region including a pixel portion formation region, and then light is applied to the photocatalyst-containing layer through a photomask. The ink affinity (wettability) of the region where the pixel portion is formed may be selectively increased by irradiating and exposing. Examples of photocatalysts include titanium oxide and zinc oxide.

The color filter 100 may have an ink-receiving layer containing hydroxypropylcellulose, polyvinyl alcohol, gelatin, or the like between the substrate 40 and the pixel portion 10 .
Moreover, the color filter may have a protective layer on the pixel section 10 . This protective layer is provided to planarize the color filter and prevent components contained in the pixel section 10 and components contained in the photocatalyst-containing layer from eluting into other layers.
As a constituent material of the protective layer, a known material used as the protective layer of the color filter 100 can be used.

Further, in manufacturing the light conversion layer 30 and the color filter 100, the pixel portion may be formed by the photolithography method instead of the inkjet method.
In this case, first, the ink composition is applied in layers on the substrate 40 to form an ink composition layer. Next, after the ink composition layer is exposed in a predetermined pattern, it is developed using a developer. Thereby, the pixel portion 10 made of the cured ink composition is formed.
Since the developer is usually alkaline, an alkali-soluble material is used as the material for the ink composition. However, the inkjet method is superior to the photolithography method from the viewpoint of efficiency of material usage. This is because the photolithographic method, in principle, removes approximately two-thirds or more of the material, which wastes the material. Therefore, in the present embodiment, it is preferable to use the ink composition as an inkjet ink and form the pixel portion by an inkjet method.

In addition to the luminescent nanoparticle composite described above, the pixel portion 10 of the light conversion layer 30 of the present embodiment may further contain a pigment having substantially the same color as the luminescent color of the luminescent nanoparticle composite. In order to contain the pigment in the pixel portion 10, the pigment may be mixed with the ink composition.

In addition, one or two of the red light-emitting pixel portion (R), the green light-emitting pixel portion (G), and the blue light-emitting pixel portion (B) in the light conversion layer 30 of the present embodiment The part may be a pixel part that does not contain the luminescent nanoparticle composite but contains a coloring material.
Here, usable coloring materials include, for example, a diketopyrrolopyrrole pigment and/or an anionic red organic dye for the red light-emitting pixel portion (R). At least one selected from the group consisting of a halogenated copper phthalocyanine pigment, a phthalocyanine green dye, a mixture of a phthalocyanine blue dye and an azo yellow organic dye is used in the green light emitting pixel portion (G). The blue light-emitting pixel portion (B) includes an ε-type copper phthalocyanine pigment and/or a cationic blue organic dye.
The amount of these colorants used is 1 to 5 masses based on the total mass of the pixel portion (cured product of the ink composition) 10 from the viewpoint of preventing a decrease in transmittance when mixed in the light conversion layer 30. %.

EXAMPLES The present invention will be specifically described below with reference to Examples. However, the present invention is not limited only to the following examples.
The compounds used in the Examples and the like are shown below.

<Photopolymerizable compound>
・ HDDMA: 1,6-hexanediol dimethacrylate (product name “NK Ester HD-N”, manufactured by Shin-Nakamura Chemical Co., Ltd.)
・ HDDA: 1,6-hexanediol diacrylate (product name “Miramer M200”, manufactured by MIWON)
・ DPGDA: dipropylene glycol diacrylate (product name “Miramer M222”, manufactured by MIWON)
・ DCPEA: dicyclopentenyloxyethyl acrylate (product name “Funkryl FA-512AS”, manufactured by Showa Denko Materials Co., Ltd.)
・ DCPEM: dicyclopentenyloxyethyl methacrylate (product name “Funkryl FA-512MT”, manufactured by Showa Denko Materials Co., Ltd.)
・AOMA: 2-(allyloxymethyl) methyl acrylate (product name “AOMA”, manufactured by Nippon Shokubai Co., Ltd.)
<Photoinitiator>
・TPO-H: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (product name “Omnirad TPO-H”, manufactured by IGM Resins B.V.)
· 819: bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (product name "Omnirad 819", manufactured by IGM Resins B.V.)
<Zinc compound>
・ ZDBC: zinc dibutyldithiocarbamate (product name “Nocceller BZ-P”, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)
<Antioxidant>
・ Agent 1: Bis (decyl) pentaerythritol diphosphite (product name “JPE-10”, manufactured by Johoku Chemical Industry Co., Ltd.)
Agent 2: Pentaerythritol tetrakis [3-[3,5-di(t-butyl)-4-hydroxyphenyl]propionate]
(Product name “irganox 1010”, manufactured by BASF Japan Ltd.)

<Luminescent nanoparticles>
Luminescent nanoparticles were prepared as follows.
(1) <core synthesis>
0.88 g (3 mmol) of indium acetate, 0.66 g (3 mmol) of zinc acetate dihydrate, 10 g of 1-octadecene (ODE) and 3.16 g (15.8 mmol) of lauric acid were added to the reaction flask and then extruded under vacuum. at 140° C. for 2 hours.
Then, the temperature of the mixture was raised to 250° C. under a nitrogen atmosphere. At this temperature, 0.25 g (1 mmol) of tris(trimethylsilyl)phosphine (TMSP) was quickly introduced into the reaction flask and the reaction temperature was maintained at 230°C.
After 5 minutes, the reaction was stopped by removing the heater and the resulting reaction solution was cooled to room temperature. 8 ml of toluene and 20 ml of ethanol were then added to the reaction solution in the glovebox. Subsequently, centrifugation was performed and InP nanoparticles were obtained by decanting the supernatant.
The resulting InP nanoparticles were then dispersed in ODE. As a result, a dispersion containing 5% by mass of InP nanoparticles (ODE dispersion) was obtained.

(2) <shell formation>
(2-1) 1.1 g (5 mmol) of zinc acetate dihydrate, 2.8 g (10 mmol) of oleic acid and 7.1 g of ODE were added to a reaction flask and then heated at 120° C. for 2 hours under vacuum, A 0.4 M zinc precursor solution 1 was prepared.
(2-2) 2.5 g of the ODE dispersion of InP nanoparticles (InP cores) obtained in (1) above and 2.5 g of ODE were added to a reaction flask and heated at 80° C. for 30 minutes under vacuum.
Then, after heating to 200° C. under a nitrogen atmosphere, 3 mL of the 0.4 M zinc precursor solution 1 obtained in (2-1) above and 1.0 M trioctylphosphine selenide (TOPSe ) was added and held at 200° C. for 30 minutes to form a ZnSe shell.
Subsequently, the temperature was raised to 230° C., and 1 mL of the 0.4 M zinc pre-solution 1 obtained in (2-1) above and 0.4 mL of 1.0 M trioctylphosphine sulfide (TOPS) were added to the reaction flask. After that, the temperature was maintained at 230° C. to form a ZnS shell.
After 30 minutes, the reaction was stopped by removing the heater and the resulting reaction solution was cooled to room temperature. 8 ml of toluene and 20 ml of ethanol were then added to the reaction solution. Subsequently, centrifugation was performed, and the supernatant was decanted to obtain luminescent nanoparticles 1 of a core-shell structure type (InP/ZnSe/ZnS) having a core containing In and P and a ZnSe shell and a ZnS shell.

<Organic ligand>
Carboxylic acid 1 to carboxylic acid 16 as carboxylic acid compounds were prepared as follows.

Carboxylic acid 1:
18 g (110 mmol, manufactured by Tokyo Chemical Industry Co., Ltd.) of diethylene glycol monophenyl ether, 10 g (100 mmol) of succinic anhydride, 11 g (110 mmol) of triethylamine and 50 g of toluene were added to the reaction flask, and then stirred at room temperature for 3 hours under a nitrogen atmosphere. .
50 g of ethyl acetate was added to the reaction solution, washed once with 100 mL of 1N hydrochloric acid, and washed twice with saturated brine. The organic layer was dried over magnesium sulfate and then concentrated to obtain carboxylic acid 1.
Carboxylic acid 2:
Carboxylic acid 2 was obtained in the same manner as in the production of carboxylic acid 1 using 110 mmol of diethylene glycol monophenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 3:
Carboxylic acid 3 was obtained in the same manner as carboxylic acid 1 using 110 mmol of diethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of succinic anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 4:
Carboxylic acid 4 was obtained in the same manner as carboxylic acid 1 using 110 mmol of diethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 5:
Carboxylic acid 5 was obtained in the same manner as carboxylic acid 1 using 110 mmol of ethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 6:
Carboxylic acid 6 was obtained in the same manner as carboxylic acid 1 using 110 mmol of propylene glycol monophenyl ether (Nippon Nyukazai Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 7:
Carboxylic acid 7 was obtained in the same manner as carboxylic acid 1 using 110 mmol of tetrahydrofurfuryl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 8:
Carboxylic acid 8 was obtained in the same manner as carboxylic acid 1 using 110 mmol of glycerol formal (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 9:
After adding 19 g (100 mmol, manufactured by Tokyo Chemical Industry Co., Ltd.) of phenoxyethyl acrylate, 11 g (105 mmol) of 3-mercaptopropionic acid, 11 g (110 mmol) of triethylamine and 50 g of toluene to a reaction flask, the mixture was stirred at 80° C. for 6 hours under a nitrogen atmosphere. bottom.
50 g of ethyl acetate was added to the reaction solution, washed once with 100 mL of 1N hydrochloric acid, and washed twice with saturated brine. The organic layer was dried over magnesium sulfate and then concentrated to obtain carboxylic acid 9.
Carboxylic acid 10:
Carboxylic acid 10 was obtained in the same manner as carboxylic acid 9 using 100 mmol of tetrahydrofurfuryl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 105 mmol of 3-mercaptopropionic acid, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 11:
Carboxylic acid 11 was obtained in the same manner as in the production of carboxylic acid 1 using 110 mmol of triethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of succinic anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 12:
Carboxylic acid 12 was obtained in the same manner as carboxylic acid 1 using 110 mmol of polyethylene glycol monomethyl ether (manufactured by Merck) having a number average molecular weight of 350, 100 mmol of succinic anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 13:
Carboxylic acid 13 was obtained in the same manner as in the production of carboxylic acid 1 using 110 mmol of tetraethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of succinic anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 14:
Carboxylic acid 14 was obtained in the same manner as carboxylic acid 1 using 110 mmol of hexaethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine and 50 g of toluene.
Carboxylic acid 15:
Carboxylic acid 15 was prepared in the same manner as in the production of carboxylic acid 1, using 110 mmol of triethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of cis-1,2-cyclohexanedicarboxylic anhydride, 100 mmol of glutaric anhydride, 110 mmol of triethylamine, and 50 g of toluene. got
Carboxylic acid 16:
Carboxylic acid 16 was produced in the same manner as in the production of carboxylic acid 1, using 110 mmol of diethylene glycol monophenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of cis-1,2-cyclohexanedicarboxylic anhydride, 100 mmol of glutaric anhydride, 110 mmol of triethylamine, and 50 g of toluene. Obtained.
The chemical structural formulas of the obtained carboxylic acids 1 to 16 are shown.

[Production of luminescent nanoparticle composite]
[Example 1]
1.0 g of luminescent nanoparticles 1, 0.8 g of carboxylic acid 1 as an organic ligand, and 8.2 g of propylene glycol monomethyl ether acetate (PGMEA) were added to the reaction flask, followed by 3 Stirred for an hour.
After cooling the reaction solution to room temperature, 10 ml of acetone and 60 ml of heptane were added to reprecipitate the synthesized product. Subsequently, centrifugation was performed, and the supernatant was decanted to obtain a luminescent nanoparticle composite A-1.

[Examples 2 to 10, Comparative Examples 1 to 6]
Luminescent nanoparticle complexes A-2 to A-10 and B-1 to B were prepared in the same manner as in Example 1 except that the types of luminescent nanoparticles and organic ligands were changed as shown in Table 1. -4 was obtained.
In Comparative Examples 5 and 6, reprecipitation was not possible and no luminescent nanoparticle composite was obtained. Carboxylic acid 15 and carboxylic acid 16, which have a substituent at the α-position of the carboxyl group, could not be reprecipitated with an acetone-heptane mixed solvent because the ligand exchange reaction did not progress sufficiently due to steric hindrance due to the substituent. It is thought that
Table 1 also shows the Hansen solubility parameter δD values and molecular weights of the organic ligands used.
The δD values of the Hansen Solubility Parameters were estimated using HSPiP.
The number average molecular weight of an organic ligand having a molecular weight distribution was obtained from the integral ratio of ¹ HNMR.

<Production of Light-scattering Particle Dispersion>
In a container filled with argon gas, 33.0 g of titanium oxide (product name: CR-60-2, manufactured by Ishihara Sangyo Co., Ltd., average particle diameter (volume average diameter): 210 nm) and a polymer dispersant (Ajisper 1.0 g of PB-821, manufactured by Ajinomoto Fine-Techno Co., Ltd.) and 26.0 g of 1,4-butanediol diacrylate were mixed.
After that, zirconia beads (diameter: 1.25 mm) were added to the obtained mixture, the mixture was dispersed by shaking for 2 hours using a paint conditioner, and the zirconia beads were removed with a polyester mesh filter to remove light. A scattering particle dispersion (titanium oxide content: 55% by mass) was obtained.

1. Preparation of Ink Composition <Ink Composition 1>
The luminescent nanoparticle composite A-1, the photopolymerizable compound, the photopolymerization initiator, the light-scattering particle dispersion, and the antioxidant, the content of each component shown in Table 2 (unit: mass Part), and mixed uniformly in a container filled with argon gas.
After that, the mixture was filtered through a filter with a pore size of 5 μm in a glove box.
Furthermore, argon gas was introduced into the container containing the obtained filtrate, and the inside of the container was saturated with argon gas.
Ink composition 1 was then obtained by removing the argon gas under reduced pressure.

<Ink Compositions 2 to 20>
Each luminescent nanoparticle composite, a photopolymerizable compound, a photopolymerization initiator, a light-scattering particle dispersion, a dithiocarbamic acid-based compound, and an antioxidant are added to the amount shown in Table 2 (unit : parts by mass), and in the same manner as for ink composition 1, ink compositions 2 to 20 were obtained.

2. Evaluation of Ink Composition 2-1. Preparation of Samples for External Quantum Efficiency Evaluation Each ink composition was applied to a glass substrate in the air by a spin coater to a thickness of 10 μm.
Under a nitrogen atmosphere, the coating film is cured by irradiating UV light with a UV irradiation device using an LED lamp having a dominant wavelength of 395 nm so that the integrated light amount becomes 1000 mJ/cm ² , and a cured product of the ink composition is deposited on the glass substrate. A layer (light conversion layer) was formed. Thus, an evaluation sample, which is a substrate having a light conversion layer, was produced.

2-2. Measurement of External Quantum Efficiency (EQE) A blue LED (manufactured by CCS Co., Ltd.) that emits light having an emission peak at a wavelength of 450 nm was used as a surface emitting light source. As a measuring device, an integrating sphere was connected to a radiation spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., "MCPD-9800"), and the integrating sphere was placed above the blue LED.
Between the blue LED and the integrating sphere, 2-1. Each evaluation sample prepared in 1 was inserted, and the spectrum observed by lighting the blue LED and the illuminance at each wavelength were measured.

The external quantum efficiency (EQE) was determined as follows from the spectrum and illuminance measured by the above measuring device.
EQE is a value that indicates how much of the light (photons) incident on the light conversion layer is radiated to the observer side as fluorescence. Therefore, if this value is large, it indicates that the light conversion layer is excellent in light emission characteristics, which is an important evaluation index.
EQE (%) = P1 (Green)/E (Blue) x 100

Here, E (Blue) and P1 (Green) each represent the following values.
E (Blue) represents the total value of “illuminance×wavelength/hc” in the wavelength range of 380 to 490 nm.
P1 (Green) represents the total value of “illuminance×wavelength/hc” in the wavelength range of 500 to 650 nm.
These values correspond to the number of photons observed. In addition, h represents Planck's constant and c represents the speed of light.

2-3. Heat resistance 2-1. Each evaluation sample prepared in 1 was transferred onto a 180° C. hot plate placed in a glove box under a nitrogen atmosphere and heated for 30 minutes. After cooling the evaluation sample to room temperature, the EQE was subjected to 2-2. was measured in the same manner as in , the EQE retention rate was determined by the following formula, and the heat resistance was evaluated according to the following criteria.
Maintenance rate = [EQE after heating]/[EQE before heating] x 100
[Evaluation criteria]
◎: 98% or more ○: 95% or more and less than 98% △: 90% or more and less than 95% ×: less than 90%

2-4. Atmospheric Storage Stability (Atmospheric Stability)
2-3. Each evaluation sample prepared in 2-2. EQE was measured in the same manner as. The retention rate of EQE after irradiation relative to EQE before irradiation was determined by the following formula, and atmospheric stability was evaluated according to the following criteria.
Retention rate = [EQE after 24 hours]/[Early EQE] x 100
[Evaluation criteria]
◎: 98% or more ○: 95% or more and less than 98% △: 90% or more and less than 95% ×: less than 90%

2-5. Viscosity of Ink Composition The viscosity at 40° C. of the ink composition prepared in 1 was measured using an E-type viscometer, and the viscosity was evaluated according to the following criteria.
[Evaluation criteria]
◎: 12 mPa s or less ○: 12 mPa s exceeded, 13 mPa s or less △: 13 mPa s exceeded, 14 mPa s or less ×: 14 mPa s exceeded

2-6. After storing the ink composition prepared in Storage Stability 1 of the ink composition for 2 weeks in a constant temperature tester kept at 40° C., the viscosity of the ink composition was measured, and the viscosity increase rate of the ink composition was calculated by the following formula. , and the storage stability was evaluated according to the following criteria.
Thickening rate = ([viscosity after 2 weeks] - [initial viscosity]) / [initial viscosity] x 100
[Evaluation criteria]
⊚: Thickness increase of 3% or less ◯: Thickness increase of more than 3% and 5% or less △: Thickness increase of more than 5% Table 2 shows the evaluation results.

The luminescent nanoparticle composite of the present invention is excellent in atmospheric storage stability and heat resistance. An ink composition containing such a luminescent nanoparticle composite can provide a light conversion layer with excellent luminous properties, a color filter used in mobile terminals, televisions, monitors, etc., and can be used for liquid crystal display devices and self-luminous display devices. is useful as

10 pixel section 10a first pixel section 10b second pixel section 10c third pixel section 11a first luminescent nanoparticle composite 11b second luminescent nanoparticle composite 12a first light scattering particles 12b second light scattering particles 12c third light scattering particles 20 light shielding part 30 light conversion layer 40 base material 100 color filter

Claims (17)

A luminescent nanoparticle complex in which an organic ligand is coordinated to the surface of the luminescent nanoparticles,
A luminescent nanoparticle complex, wherein the organic ligand is a compound represented by the following formula (1) and having a molecular weight of 200-350.

[In formula (1), R ¹ represents an alkylene group having 1 to 6 carbon atoms, and one or more non-adjacent -CH ₂ - in the alkylene group are independently -O -, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH- or -NHCO-, and R ² has 1 to 10 carbon atoms represents an alkylene group or (poly)oxyalkylene group, and X represents a substituent having a cyclic structure. ] The luminescent nanoparticle composite according to claim 1, wherein said X in said formula (1) is an aryl group. 3. The luminescent nanoparticle complex according to claim 1, wherein the δD value of the Hansen solubility parameter of the organic ligand is 17.4 MPa ^0.5 or more. The luminescent nanoparticle composite according to any one of claims 1 to 3, wherein the luminescent nanoparticles are core-shell structured luminescent nanoparticles containing indium and phosphorus in the core. An ink composition comprising the luminescent nanoparticle composite according to any one of claims 1 to 4 and a photopolymerizable compound. 6. The ink composition according to claim 5, wherein the photopolymerizable compound is a photoradically polymerizable compound. 7. The ink composition according to claim 5 or 6, wherein the photopolymerizable compound is alkali-insoluble. 8. The ink composition according to any one of claims 5 to 7, further comprising an antioxidant. 9. The ink composition according to any one of claims 5 to 8, further comprising a zinc compound having zinc as a central metal and having two ligands coordinated to the zinc. 10. The ink composition according to any one of claims 5 to 9, which is used in a droplet ejection method by an inkjet system. 11. The ink composition according to any one of claims 5 to 10, which is used for color filters. A light conversion layer comprising a cured product of the ink composition according to any one of claims 5 to 11. A light conversion layer comprising a cured product of the ink composition according to any one of claims 5 to 11, wherein the light conversion layer is alkali-insoluble. A light conversion layer comprising a plurality of pixel units,
12. A light conversion layer, wherein the plurality of pixel portions have pixel portions containing a cured product of the ink composition according to any one of claims 5 to 11. further comprising a light shielding portion provided between the plurality of pixel portions;
The plurality of pixel portions includes the cured product, and as the luminescent nanoparticle composite, absorbs light with a wavelength in the range of 420 to 480 nm and emits light with an emission peak wavelength in the range of 605 to 665 nm. a first pixel portion containing a luminescent nanoparticle composite;
A luminescent nanoparticle composite that includes the cured product and absorbs light with a wavelength in the range of 420 to 480 nm and emits light having an emission peak wavelength in the range of 500 to 560 nm as the luminescent nanoparticle composite. a second pixel portion containing
The light conversion layer according to any one of claims 12 to 14, having 16. The light conversion layer according to any one of claims 12 to 15, wherein the plurality of pixel portions further includes a third pixel portion having a transmittance of 30% or more for light with a wavelength in the range of 420 to 480 nm. . A color filter comprising the light conversion layer according to any one of claims 12-16.

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