Luminescent nanoparticle composite, ink composition, light conversion layer and color filter

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]

[0001] The present invention relates to a light-emitting nanoparticle composite, an ink composition, a light conversion layer, and a color filter. [Background technology]

[0002] Liquid crystal display devices are widely used in applications such as mobile terminals, televisions, and monitors. The color filters used in these liquid crystal display devices are manufactured by photolithography, which forms a black matrix and red, green, and blue pixel patterns. Specifically, in photolithography, a photosensitive resin composition containing coloring materials such as pigments and dyes is applied to a substrate, dried, and then exposed to UV light through a mask. Uncured portions are removed by alkaline development, and the resulting film is then baked. In recent years, self-luminous display devices that combine white-light-emitting organic electroluminescence (EL) elements with color filters have also been widely used in applications such as televisions and monitors.

[0003] However, in display devices using these color filters, at least 67% of light is theoretically absorbed by the color filters, so there is a fundamental limit to how much power consumption can be reduced by improving the transmittance of the color filters themselves.

[0004] In order to solve the problem of reducing power consumption, in recent years, attention has been focused on a method of using quantum dots, which are luminescent nanocrystalline particles, in a light conversion layer instead of conventional color filters. This light conversion layer is formed on a substrate having a black matrix, and includes a red-light-emitting quantum dot layer that is excited by blue light and emits red fluorescence, a green-light-emitting quantum dot layer that is excited by blue light and emits green fluorescence, and a blue-light-transmitting layer that transmits blue light. A liquid crystal display device or a self-luminous display device is constructed by combining this light conversion layer with a blue-emitting LED backlight or a blue-emitting organic EL element.

[0005] A display device equipped with such a light conversion layer can achieve higher light utilization efficiency than a display device equipped with a conventional color filter. Furthermore, the fluorescence emitted from the quantum dots, which has a spectrum with a narrow half-width, can be used directly to display colors on the display device, resulting in a display device with a wide color reproduction range.

[0006] For example, a method is known in which a light conversion layer is produced by forming a coating film on one side of a substrate using a photosensitive resin composition containing quantum dots, patterning the coating film by photolithography, and then curing the resulting coating film by heat treatment (see, for example, Patent Document 1). However, photolithography is complicated due to the large number of steps involved, and also generates a photosensitive resin composition that is removed by alkaline development, which inevitably results in waste of raw materials.

[0007] A manufacturing method using the inkjet method is known as a technique that can reduce waste of raw materials. The inkjet method allows the red-emitting quantum dot layer and the green-emitting quantum dot layer in the light conversion layer to be formed simultaneously, thereby improving manufacturing efficiency. Furthermore, since the entire ejected ink (photosensitive resin composition) can be used, waste of raw materials, as occurs with photolithography, is less likely to occur. For example, an example of an inkjet ink containing dispersed quantum dots that is used to pattern a light conversion layer used in combination with a blue-emitting organic EL element, has been disclosed (see, for example, Patent Document 2). On the other hand, from the viewpoint of improving the optical properties of the light conversion layer (for example, 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 dispersion stability and optical properties can be improved by treating the surface of luminescent nanocrystalline particles with a specific compound so that at least a portion of the surface has the compound as a ligand (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-53716 [Patent Document 2] International Publication No. 2008 / 001693 [Patent Document 3] International Publication No. 2020 / 162552 [Patent Document 4] Japanese Patent Application Publication No. 2020-105491 Summary of the Invention [Problem to be solved by the invention]

[0009] Ink compositions containing quantum dots and film products made from them have the problem of deterioration due to oxygen and moisture contained in the atmosphere. When supplying an ink composition containing quantum dots to a large area to produce coated or printed materials, completely isolating them from the atmosphere requires that most of the coating or printing equipment be placed under a high-purity inert gas atmosphere, which requires a huge capital investment. Furthermore, it is required that the external quantum efficiency does not decrease due to heating during the manufacturing process of the pixel part (heat resistance). However, when an ink composition containing conventional luminescent nanoparticles is used, it cannot necessarily be said that a pixel part having sufficient heat resistance is obtained.

[0010] According to the investigations of the present inventors, it has been found that, in the method of surface treating quantum dots, which are luminescent nanocrystalline particles, with specific compounds, there is still room for improvement in terms of the stability of the external quantum efficiency of carboxylic acid compounds during storage in the atmosphere and when heated. An object of the present invention is to provide a luminescent nanoparticle composite that has excellent atmospheric storage stability and heat resistance, and in particular, excellent stability in maintaining external quantum efficiency. Another object of the present invention is to provide an ink composition that contains such a luminescent nanoparticle composite and has excellent dispersibility and is capable of preventing a decrease in luminescent properties, as well as a light conversion layer and a color filter that have excellent luminescent properties. [Means for solving the problem]

[0011] The present inventors have discovered that atmospheric storage stability and heat resistance can be improved in luminescent nanoparticle composites by using a carboxylic acid compound having a specific chemical structure, and have completed the present invention.

[0012] That is, one aspect of the present invention relates to a luminescent nanoparticle composite 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 has a molecular weight of 200 to 350:

[0013] [ka] [In formula (1), R 1 represents an alkylene group having 1 to 6 carbon atoms, and one -CH2- in the alkylene group is -OCO- , or one of two or more non-adjacent —CH2— in the alkylene group is substituted with -OCO- the remaining -CH2- is replaced by at least one of -O-, -S-, -CO-, -OCO-, -NH-, -CONH-, or -NHCO-; R 2 represents an alkylene group or a (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.]

[0014] The luminescent nanoparticle composite of the above aspect makes it possible to form an ink composition that is excellent in dispersibility and can prevent a decrease in luminescent properties, and a light conversion layer and a color filter that are excellent in luminescent properties.

[0015] In one aspect of the present invention, X in formula (1) is an aryl group.

[0016] In one aspect of the present invention, the δD value of the Hansen solubility parameter of the organic ligand is 17.4 MPa 0.5 That's all.

[0017] In one aspect of the present invention, the luminescent nanoparticles are luminescent nanoparticles of a core-shell structure containing indium and phosphorus in the core.

[0018] One aspect of the present invention is an ink composition containing the above-described light-emitting nanoparticle composite and a photopolymerizable compound.

[0019] In one aspect of the present invention, the photopolymerizable compound is a photoradical polymerizable compound.

[0020] In one aspect of the present invention, the photopolymerizable compound is alkali-insoluble.

[0021] In one aspect of the present invention, the ink composition contains an antioxidant.

[0022] In one aspect of the present invention, the ink composition contains a zinc compound having zinc as a central metal and having two ligands coordinated to the zinc.

[0023] In one aspect of the present invention, the ink composition is used in a droplet ejection method using an inkjet system.

[0024] In one aspect of the present invention, the ink composition is for use in a color filter.

[0025] One aspect of the present invention relates to a light conversion layer comprising a cured product of the ink composition described above.

[0026] In one aspect of the present invention, the light conversion layer is alkali-insoluble.

[0027] In one aspect of the present invention, the light conversion layer includes a plurality of pixel portions, and the plurality of pixel portions include pixel portions containing a cured product of the ink composition described above.

[0028] In one aspect of the present invention, the light conversion layer further comprises a light-shielding portion provided between a plurality of pixel portions, and the plurality of pixel portions comprise a first pixel portion that contains a cured product of the ink composition described above and that contains, as a light-emitting nanoparticle composite, a light-emitting nanoparticle composite that absorbs light with a wavelength in the range of 420 to 480 nm and emits light having a peak emission wavelength in the range of 605 to 665 nm, and a second pixel portion that contains, as a light-emitting nanoparticle composite, a light-emitting nanoparticle composite that absorbs light with a wavelength in the range of 420 to 480 nm and emits light having a peak emission wavelength in the range of 500 to 560 nm.

[0029] In one aspect of the present invention, the light conversion layer includes a third pixel portion having a transmittance of 30% or more for light having a wavelength in the range of 420 to 480 nm.

[0030] In one aspect of the present invention, the light conversion layer is a color filter. [Effects of the Invention]

[0031] According to the present invention, it is possible to provide a luminescent nanoparticle composite that has excellent atmospheric storage stability and heat resistance, and in particular excellent stability in maintaining external quantum efficiency; an ink composition that contains such a luminescent nanoparticle composite, has excellent dispersibility, and is capable of preventing a decrease in luminescent properties; and a light conversion layer and color filter that have excellent luminescent properties. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a schematic cross-sectional view of a color filter according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be described in detail. In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively.

[0034] The present invention provides a luminescent nanoparticle composite 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 has a molecular weight of 200 to 350:

[0035] [ka] [In formula (1), R 1 represents an alkylene group having 1 to 6 carbon atoms, in which one or two or more non-adjacent -CH2- groups may be independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH-, or -NHCO-; R 2 represents an alkylene group or a (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.]

[0036] The luminescent nanoparticle composite of the present invention is used, for example, in an ink composition for forming pixel portions of a light conversion layer in a color filter or the like. That is, the luminescent nanoparticle composite of the present invention is preferably used in an ink composition for forming a light conversion layer (for example, for forming pixel portions of a color filter). Such an ink composition has excellent dispersibility of the luminescent nanoparticle composite and can prevent deterioration of optical properties. The reason why the above effect is obtained is not clear, but the inventors speculate as follows.

[0037] Because organic ligands with cyclic structures have a rigid molecular structure, their molecular motion is restricted compared to linear or branched organic ligands. Therefore, when organic ligands with cyclic structures are coordinated to the surface of luminescent nanoparticles, the generation of radicals during storage in the atmosphere or upon heating is suppressed. Furthermore, when an organic ligand with a molecular weight below a certain level is used, cyclic structures are introduced densely near the luminescent nanoparticles, which increases the cohesive energy density and reduces gas permeability to oxygen, moisture, and other gases. Therefore, since the radicals, oxygen, and moisture that cause oxidation of the surface elements of the luminescent nanoparticles are reduced, the deterioration associated with oxidation of the surface elements is suppressed in the luminescent nanoparticle composite in which an organic ligand having a cyclic structure and a molecular weight below a certain level is coordinated to the luminescent nanoparticle, and the external quantum efficiency is maintained with excellent stability when stored in air or when heated.

[0038] Furthermore, by using a carboxylic acid compound with a specific structure as the organic ligand, the affinity with both the light-emitting nanoparticles and the photopolymerizable compound is increased, allowing them to be uniformly distributed in the ink composition. Therefore, the luminescent nanoparticle composites are dispersed uniformly in the ink composition, and deterioration of the luminescent nanoparticles can be prevented. As a result, it is believed that the present invention can provide an ink composition that has excellent dispersibility of luminescent nanoparticle composites and is capable of sufficiently preventing deterioration of optical properties. Such an effect of preventing deterioration of optical properties is suitably exhibited during storage of the ink composition, during production of pixel portions, etc.

[0039] Furthermore, an ink composition containing the luminescent nanoparticle composite of the present invention can provide pixel portions with excellent external quantum efficiency. Furthermore, the ink composition of the present invention allows the luminescent nanoparticles to be uniformly dispersed, making it easy to achieve excellent ejection stability in a droplet ejection method using an inkjet system (hereinafter also referred to as the "inkjet method"). In other words, the ink composition of the present invention can be suitably used in the inkjet method.

[0040] Furthermore, according to the ink composition of the present invention, the luminescent nanoparticle composite contains a specific carboxylic acid compound, which prevents a decrease in external quantum efficiency due to heating. In other words, the ink composition of the present invention makes it easy to form pixel parts that are excellent in heat resistance (stability of external quantum efficiency).

[0041] The ink composition of one embodiment can be used as an ink for producing color filters, but it is also preferable to prepare it appropriately to be more suitable for inkjet printing than for photolithography, in that it can form pixel portions (light conversion layers) by simply using the required amount in the required locations without wasting relatively expensive materials such as luminescent nanoparticles and solvents. In addition to the luminescent nanoparticle composite and photopolymerizable compound, such ink composition can further contain other components such as light-scattering particles, polymer dispersants, and organic solvents, as described below, as necessary.

[0042] [Luminescent nanoparticle composites] First, the luminescent nanoparticles and organic ligands that constitute the luminescent nanoparticle composite of the present invention will be described.

[0043] [Luminescent nanoparticles] Generally, luminescent nanoparticles are nano-sized crystals that absorb excitation light and emit fluorescence or phosphorescence, and have a maximum particle size of 100 nm or less as measured by, for example, a transmission electron microscope or a scanning electron microscope.

[0044] Luminescent nanoparticles can, for example, absorb light of a predetermined wavelength and then emit light (fluorescence or phosphorescence) of a wavelength different from the absorbed wavelength. The luminescent nanoparticles may be red-luminescent nanocrystalline particles that emit light having an emission peak in the wavelength range of 605 to 665 nm (red light), green-luminescent nanocrystalline particles that emit light having an emission peak in the wavelength range of 500 to 560 nm (green light), or blue-luminescent nanocrystalline particles that emit light having an emission peak in the wavelength range of 420 to 480 nm (blue light). Furthermore, the light absorbed by the luminescent nanoparticles may be, for example, light with a wavelength in the range of 400 nm or more and less than 500 nm (particularly, wavelengths of 420 to 480 nm) (blue light), or light with a wavelength in the range of 200 nm to 400 nm (ultraviolet light). The emission peak wavelength of the luminescent nanoparticles can be confirmed, for example, in a fluorescence spectrum or phosphorescence spectrum measured using a spectrofluorometer.

[0045] The red light-emitting nanocrystalline particles preferably have an emission peak in the wavelength range 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, 632 nm or less, or 630 nm or less, and preferably have an emission peak in the wavelength range of 628 nm or more, 625 nm or more, 623 nm or more, 620 nm or more, 615 nm or more, 610 nm or more, 607 nm or more, or 605 nm or more. These upper and lower limit values ​​can be combined in any desired manner. In the following similar descriptions, the upper and lower limit values ​​individually described can also be combined in any desired manner.

[0046] The green light-emitting nanocrystalline particles preferably 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, and preferably have 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.

[0047] The blue light-emitting nanocrystalline particles preferably 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, and more preferably have 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.

[0048] According to the solution of the Schrodinger wave equation of the well-well potential model, the wavelength (emission color) of light emitted by luminescent nanoparticles depends on the size (e.g., particle diameter) of the luminescent nanoparticles, but also on the energy gap of the luminescent nanoparticles. Therefore, the emission color can be selected (adjusted) by changing the constituent material and size of the luminescent nanoparticles used.

[0049] The luminescent nanoparticles may be luminescent nanoparticles containing a semiconductor material (luminescent semiconductor nanoparticles). Examples of such luminescent nanoparticles include quantum dots and quantum rods. Among these, quantum dots are preferred as luminescent nanoparticles from the viewpoints of ease of control of the emission spectrum, reduction of production costs, and improvement of mass productivity while ensuring reliability.

[0050] The luminescent nanoparticles constituting the luminescent nanoparticle composite of the present invention are luminescent nanoparticles of a core-shell structure 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 that covers at least a portion of the core and contains a second semiconductor material different from the first semiconductor material. Furthermore, the luminescent nanoparticle may have, in addition to a shell (first shell) containing the second semiconductor material, a further shell (second shell) that covers at least a portion of the first shell and contains a third semiconductor material different from the first and second semiconductor materials. In other words, the structure of the luminescent nanoparticle may be a structure consisting of a core, a first shell, and a second shell (core / shell / shell structure). Furthermore, each of the core and the shell may be a mixed crystal containing two or more semiconductor materials (for example, InP+GaP, ZnS+ZnSe, etc.). The luminescent nanoparticle composite of the present invention contains In and P as constituent elements in the core, and therefore has a narrow band gap, making it suitable for use in applications that emit visible light. By using a semiconductor material with a large band gap 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.

[0051] Examples of the first semiconductor material containing In and P that constitutes the core of the luminescent nanoparticle include InP, InNP, InPAs, InPSb, GaInP, GaInNP, GaInPAs, GaInPSb, InAlNP, InAlPAs, and InAlPSb.

[0052] The second or third semiconductor material constituting the shell of the luminescent nanoparticle preferably comprises at least one semiconductor material selected from the group consisting of II-VI semiconductors, III-V semiconductors, I-III-VI semiconductors, Group IV semiconductors, and I-II-IV-VI semiconductors.

[0053] 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, GaS b, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaInP, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, Al PAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNA s, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb;SnS, SnSe, SnTe, PbS, PbSe, PbTe , SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; Si, Ge, SiC, SiGe, AgInSe2, CuGaSe2, CuInS2, CuGaS2, CuInSe2, AgInS2, AgInGaS, AgGaSe2, AgGaS2, C, Si and Ge, etc.

[0054] From the viewpoints of easily controlling the emission spectrum, reducing production costs, and improving mass productivity while ensuring reliability, the luminescent nanoparticles preferably contain at least one semiconductor material selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, InP, InAs, InSb, GaP, GaAs, GaSb, AgInS2, AgInSe2, AgInTe2, AgInGaS, AgGaS2, AgGaSe2, AgGaTe2, CuInS2, CuInSe2, CuInTe2, CuGaS2, CuGaSe2, CuGaTe2, Si, C, Ge, and Cu2ZnSnS4.

[0055] Specific examples of the luminescent nanoparticles that constitute the luminescent nanoparticle composite of the present invention include nanoparticles with a core / shell structure having an InP core and a ZnS shell, nanoparticles with a core / shell structure having an InP core and a shell made of a mixed crystal of ZnS and ZnSe, nanoparticles with a core / shell / shell structure having an InP core, a first shell made of ZnSe and a second shell made of ZnS, and nanoparticles with a core / shell / shell structure having an InP core, a first shell made of a mixed crystal of ZnS and ZnSe and a second shell made of ZnS. These can be used as red-, green-, and blue-emitting nanocrystalline particles.

[0056] By adjusting the average particle diameter of luminescent nanoparticles with the same chemical composition, the color of light emitted from the luminescent nanoparticles can be changed to either red or green. Furthermore, it is preferable to use luminescent nanoparticles that themselves have as little adverse effect as possible on the human body, etc. Therefore, it is preferable to use luminescent nanoparticles that contain as little cadmium, selenium, etc. as possible alone, or when using luminescent nanoparticles that contain the above elements (cadmium, selenium, etc.), to combine them with other luminescent nanoparticles so that the amount of these elements is as small as possible.

[0057] The shape of the luminescent nanoparticles is not particularly limited and may be any geometric shape or any irregular shape, such as a sphere, ellipsoid, pyramid, disk, branch, net, or rod. However, it is preferable to use luminescent nanoparticles with a particle shape that is less directional (for example, spherical, tetrahedral, or other particles), as this will further enhance the uniformity and fluidity of the ink composition containing the luminescent nanoparticle composite of the present invention, as described below.

[0058] The average particle diameter (volume average diameter) of the luminescent nanoparticles is preferably 1 nm or more, more preferably 1.5 nm or more, and even more preferably 2 nm or more, from the viewpoint of easily obtaining light emission of the desired wavelength and of excellent dispersibility and storage stability. Furthermore, 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 facilitating the production of light with a desired wavelength. The average particle size (primary particle size) of luminescent nanoparticles can be determined by directly observing any number of luminescent nanoparticles using a transmission electron microscope (TEM) or scanning electron microscope (SEM), calculating the diameter of each particle from the ratio of their long and short diameters in a projected two-dimensional image, and then averaging the results.The size and shape of luminescent nanoparticles are thought to depend on their chemical composition, structure, manufacturing method, manufacturing conditions, etc.

[0059] The luminescent nanoparticles can be preferably particles that can be dispersed in a colloidal form in an organic solvent, a photopolymerizable compound, etc. The organic solvent is as described below. Commercially available luminescent nanoparticles can also be used, such as indium phosphide / zinc sulfide and D-dots manufactured by NN-Labs, and InP / ZnS manufactured by Aldrich.

[0060] [Organic Ligands] The organic ligand constituting the luminescent nanoparticle composite of the present invention contains one or more carboxylic acid compounds having one or more carboxy groups (hereinafter also referred to simply as "carboxylic acid compounds"). In the luminescent nanoparticle composite of the present invention, the surface (shell portion) of the luminescent nanoparticle is passivated (modified) with the carboxylic acid compound. The carboxylic acid compound as the organic ligand has a carboxyl group (-COOH) and can be coordinated to the surface of the luminescent nanoparticles.

[0061] The carboxylic acid compound is represented by the following formula (1).

[0062] [ka] [In formula (1), R 1 represents an alkylene group having 1 to 6 carbon atoms, in which one or two or more non-adjacent -CH2- groups may be independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH-, or -NHCO-; R 2 represents an alkylene group or a (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.]

[0063] R 1 Examples of the alkylene group having 1 to 6 carbon atoms (including those substituted with -CH2-) represented by the formula (2-1) include a methylene group, an ethylene group, a methylmethylene group, a methylethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and groups represented by the following formulas (2-1) to (2-14). Among these, formula (2-1), (2-2), (2-3), (2-4), (2-5), (2-6), (2-7) or (2-8) is preferred, and formula (2-1) or (2-2) is more preferred. The star symbols in the formulae (2-1) to (2-14) represent bonds to adjacent groups.

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[0077] [ka] R 2 Examples of the alkylene group having 1 to 10 carbon atoms represented by include a methylene group, an ethylene group, a methylmethylene group, a methylethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group. Examples of the (poly)oxyalkylene group having 1 to 10 carbon atoms represented by include an oxyethylene group, an oxypropylene group, an oxybutylene group, a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group, an oxyethylene-oxypropylene copolymerizable group, and a polyoxybutylene group. A methylene group, an oxyethylene group, or a polyoxyethylene group is preferred, and an oxyethylene group or a polyoxyethylene group is more preferred.

[0078] Examples of the substituent 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, etc. The substituent represented by X is preferably an aryl group or a monocyclic cycloalkyloxy group, and more preferably an aryl group.

[0079] The carboxylic acid compound is preferred because it is easy to obtain a cured product with excellent external quantum efficiency stability, and its δD value in the Hansen solubility parameter (HSP value) is 17.4 MPa. 0.5 It is preferable that the pressure is 17.4 to 18.2 MPa or more. 0.5 It is more preferable that the range is: In addition, the carboxylic acid compound has a Hansen solubility parameter (HSP value) ΔP of 3 to 9 MPa. 0.5, and δH is 7 to 13 MPa 0.5 It is more preferable that: Here, the Hansen solubility parameter is a parameter that represents the solubility parameter introduced by Hildebrand in three-dimensional space by dividing it into three components: δD, δP, and δH. δD indicates the effect of nonpolar interactions, δP indicates the effect of dipole-dipole forces, and δH indicates the effect of hydrogen bonding forces. Hansen solubility parameter values ​​for various compounds are listed, for example, in "Hansen Solubility Parameters: A Users Handbook" by Charles M. Hansen. Furthermore, Hansen solubility parameter values ​​for compounds not listed can be estimated using computer software (Hansen Solubility Parameters in Practice (HSPiP)).

[0080] The use of a carboxylic acid compound having such a Hansen solubility parameter as an organic ligand increases the affinity between both the luminescent nanoparticles and the photopolymerizable compound, allowing them to be uniformly distributed in the ink composition, thereby enabling the luminescent nanoparticle composite to be uniformly dispersed in the ink composition and preventing deterioration of the luminescent nanoparticles. As a result, it is believed that the present invention can provide an ink composition that has excellent dispersibility of luminescent nanoparticle composites and is capable of sufficiently preventing deterioration of optical properties. Such an effect of preventing deterioration of optical properties is suitably exhibited during storage of the ink composition, during production of pixel portions, etc.

[0081] The molecular weight of the carboxylic acid compound is 200 to 350, and more preferably 250 or more. It is believed that an ink composition that can prevent thickening during storage can be obtained by using a carboxylic acid compound with a molecular weight of 250 or more as an organic ligand. Furthermore, the molecular weight of the carboxylic acid compound is preferably 350 or less, and more preferably 320 or less, from the viewpoints of easily obtaining an appropriate viscosity for an inkjet ink and maintaining luminescence properties. The molecular weight of the carboxylic acid compound can be determined by GC-MS, GPC, or 1 The molecular weight of a carboxylic acid compound with a molecular weight distribution can be determined by HNMR. 1 It is preferable to determine by 1 HNMR, and the number average molecular weight is preferably 200 to 350.

[0082] Specific examples of suitable carboxylic acid compounds include the following compounds:

[0083] [ka]

[0084] The luminescent nanoparticle composite of the present invention can be obtained by mixing the above-described luminescent nanoparticles and a carboxylic acid compound, preferably in an organic solvent described below. The amount of the carboxylic acid compound used as the organic ligand may be 10 parts by mass or more, 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 relative to 100 parts by mass of the luminescent nanoparticles, from the viewpoints of dispersion stability of the obtained luminescent nanoparticle composite and maintenance of the luminescent properties. Furthermore, 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 relative 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 20 to 40 parts by mass, relative to 100 parts by mass of the light-emitting nanoparticles.

[0085] Furthermore, carboxylic acid compounds having a Hansen solubility parameter δD outside the above range or other organic ligands may be used in combination, provided that the effects of the present invention are not impaired. Examples of such other organic ligands include TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, linoleic acid, linolenic acid, ricinoleic acid, gluconic acid, 16-hydroxyhexadecanoic acid, 12-hydroxystearic acid, N-lauroyl sarcosine, N-oleyl sarcosine, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), phenylphosphonic acid, and octylphosphinic acid (OPA).

[0086] The following describes the configuration of the ink composition of the present invention, which contains the luminescent nanoparticle composite and photopolymerizable compound of the present invention. Note that the present invention is not limited to these configurations, and any other configuration may be added, or any configuration that exhibits a similar function may be substituted. In this specification, the term "cured product of the ink composition" refers to a cured product obtained by curing a curable component in the ink composition (or the ink composition after drying, if the ink composition contains a solvent component). The cured product of the ink composition after drying does not necessarily contain a solvent component.

[0087] [Photopolymerizable compound] The photopolymerizable compound is a compound that polymerizes upon irradiation with light, and is, for example, a photoradical polymerizable compound or a photocationic polymerizable compound. The photopolymerizable compound may be either a photopolymerizable monomer or a photopolymerizable oligomer (hereinafter, these may also be collectively referred to as "photopolymerizable monomer"). These photopolymerizable compounds are preferably used together with a photopolymerization initiator. A photoradical polymerizable compound is used together with a photoradical polymerization initiator, and a photocationic polymerizable compound is used together with a photocationic polymerization initiator. In other words, the photopolymerizable compound can contain a photopolymerizable compound and a photopolymerization initiator. The photopolymerizable compound may be a combination of a photoradical polymerizable compound and a photocationic polymerizable compound, or a compound having both photoradical and photocationic polymerizability. The photopolymerization initiator may be a combination of a photoradical polymerization initiator and a photocationic polymerization initiator.

[0088] Examples of the photoradical polymerizable compound include a monomer having an ethylenically unsaturated group (hereinafter also referred to as an "ethylenically unsaturated monomer"), a monomer having an isocyanate group, and the like. Here, the ethylenically unsaturated monomer refers to a monomer having an ethylenically unsaturated bond (carbon-carbon double bond). Examples of the ethylenically unsaturated monomer include monomers having an ethylenically unsaturated group such as a vinyl group, a vinylene group, or a vinylidene group. Note that monomers having these groups are sometimes referred to as "vinyl monomers."

[0089] The number of ethylenically unsaturated bonds in the ethylenically unsaturated monomer (for example, the number of ethylenically unsaturated groups) is preferably 1 to 3. The ethylenically unsaturated monomers may be used alone or in combination of two or more. From the viewpoint of achieving both excellent discharge stability and excellent curability, and from the viewpoint of further improving external quantum efficiency, the ethylenically unsaturated monomer may include a monomer having one or two ethylenically unsaturated groups and a monomer having two or three ethylenically unsaturated groups. That is, the ethylenically unsaturated monomer may be at least one combination selected from the group consisting of a combination of a monofunctional monomer and a difunctional monomer, a combination of a monofunctional monomer and a trifunctional monomer, and a combination of a difunctional monomer and a trifunctional monomer.

[0090] 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 its corresponding "methacrylate." The same applies to the expressions "(meth)acrylamide" and "(meth)acryloyl." The photopolymerizable compound preferably contains a compound having a (meth)acryloyl group as the ethylenically unsaturated group, and more preferably a (meth)acrylate or a (meth)acrylamide.

[0091] 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, nonylphenoxyethyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, ethoxyethoxyethyl (meth)acrylate, (Meth)acrylates such as 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, and 2-hydroxyethyl acrylate;

[0092] (meth)acrylamides such as (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, and N-dodecyl(meth)acrylamide; and the like. Among these, linear aliphatic (meth)acrylates such as dodecyl (meth)acrylate, aromatic (meth)acrylates such as phenoxyethyl (meth)acrylate, and alicyclic (meth)acrylates such as isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate are preferably used.

[0093] Examples of the monomer having two ethylenically unsaturated groups (bifunctional monomer) include 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, 1,6-hexanediol ... glycol (meth)acrylates such as 9-nonanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated (2) neopentyl glycol di(meth)acrylate [a compound obtained by diacrylate of a neopentyl glycol ethylene oxide 2-mol adduct], and propoxylated (2) neopentyl glycol di(meth)acrylate [a compound obtained by diacrylate of a neopentyl glycol propylene oxide 2-mol adduct];

[0094] alkylene glycol (meth)acrylates such as 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, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and 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 in which two hydroxyl groups of a diol obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol are substituted with (meth)acryloyloxy groups; Modified bisphenol A di(meth)acrylate, propylene oxide (PO) adduct of bisphenol A di(meth)acrylate, ethylene oxide (EO) adduct of bisphenol A di(meth)acrylate,

[0095] di(meth)acrylates such as di(meth)acrylates in which two hydroxyl groups of a triol obtained by adding 3 or more moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane are substituted with (meth)acryloyloxy groups, and di(meth)acrylates in which two hydroxyl groups of a diol obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A are substituted with (meth)acryloyloxy groups; Examples include bis(meth)acrylamides such as N,N'-methylenebis(meth)acrylamide and N,N'-ethylenebis(meth)acrylamide; 2-(allyloxymethyl)methyl acrylate, diallyl phthalate, and 1,3-diallyloxy-2-propanol. Among these, linear or branched alkylene ether di(meth)acrylates such as dipropylene glycol di(meth)acrylate, linear or branched aliphatic di(meth)acrylates such as 1,4-butanediol di(meth)acrylate and 1,6-hexanediol diacrylate, and allyl ether compounds such as methyl 2-(allyloxymethyl)acrylate are preferably used.

[0096] Specific examples of monomers having three ethylenically unsaturated groups (trifunctional monomers) include glycerin tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate.

[0097] Examples of the photocationically polymerizable compound include epoxy compounds, oxetane compounds, and vinyl ether compounds.

[0098] 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 and neopentyl glycol diglycidyl ether, and alicyclic epoxy compounds such as 1,2-epoxy-4-vinylcyclohexane and 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1.0]heptane. Commercially available epoxy compounds may also be used, such as "Celloxide 2000," "Celloxide 3000," and "Celloxide 4000" manufactured by Daicel Chemical Industries, Ltd.

[0099] Examples of the cationically polymerizable oxetane compound 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, and 3-hydroxybutyl-3-methyloxetane.

[0100] Commercially available oxetane compounds can also be used. Examples of commercially available oxetane compounds include the Aron Oxetane series (OXT-101, OXT-212, OXT-121, OXT-221, etc.) manufactured by Toagosei Co., Ltd.; Celloxide 2021, Celloxide 2021A, Celloxide 2021P, Celloxide 2080, Celloxide 2081, Celloxide 2083, Celloxide 2085, and Ethylenediaminetetraacetic acid (Ethylenediaminetetraacetic acid) manufactured by Daicel Chemical Industries, Ltd. Examples of compounds that can be used include "Epolead GT300," "Epolead GT301," "Epolead GT302," "Epolead GT400," "Epolead GT401," and "Epolead GT403" manufactured by Dow Chemical Japan, Inc.; and "Cyracure UVR-6105," "Cyracure UVR-6107," "Cyracure UVR-6110," "Cyracure UVR-6128," "ERL4289," and "ERL4299." Also, known oxetane compounds (e.g., oxetane compounds described in JP-A-2009-40830) can be used.

[0101] Examples of the vinyl ether compound include 2-hydroxyethyl vinyl ether, triethylene glycol vinyl monoether, tetraethylene glycol divinyl ether, and trimethylolpropane trivinyl ether. Further, as the photopolymerizable compound, N-vinyl compounds having a nitrogen atom and a vinyl group directly bonded to the nitrogen atom, such as N-vinyl-ε-caprolactam, N-vinylpyrrolidone, N-vinylimidazole, N-vinylcarbazole, N-vinylmorpholine, N-vinylacetamide, N-vinyl-N-methylacetamide, N-vinylformamide, and N-vinyl-5-methyl-2-oxazolidinone, as well as the photopolymerizable compounds described in paragraphs 0042 to 0049 of JP 2013-182215 A can also be used.

[0102] The photopolymerizable compound is preferably alkali-insoluble, from the viewpoint of easily obtaining pixel portions (cured products of the ink composition) that are highly reliable. In this specification, a photopolymerizable compound being alkali-insoluble means that the amount of the photopolymerizable compound that dissolves in a 1% by mass aqueous solution of potassium hydroxide at 25°C is 30% by mass or less, based on the total mass of the photopolymerizable compound. The amount of the photopolymerizable compound dissolved is preferably 10% by mass or less, and more preferably 3% by mass or less.

[0103] The content of the photopolymerizable compound in the ink composition 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, relative to 100 parts by mass of the total of components other than the organic solvent, from the viewpoints of increasing the dispersion stability of the luminescent nanoparticle composite and making it easier to obtain an appropriate viscosity for an inkjet ink, making the ink composition well curable, making it easier to prepare pixel parts with excellent shape stability, and improving the solvent resistance and abrasion resistance of the pixel parts (cured product of the ink composition). The content of the photopolymerizable compound 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, relative to 100 parts by mass of the total of components other than the organic solvent, from the viewpoint of easily obtaining an appropriate viscosity for an inkjet ink and obtaining better light-emitting properties (e.g., external quantum efficiency).

[0104] [Photopolymerization initiator] The photopolymerization initiator is, for example, a photoradical polymerization initiator or a photocationic polymerization initiator. As the photoradical polymerization initiator, a molecular cleavage type or hydrogen abstraction type photoradical polymerization initiator is suitable.

[0105] Suitable examples of molecular cleavage type photoradical polymerization initiators that can be used include 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, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide. Other molecular cleavage type photoradical polymerization initiators that may be used in combination include 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzil 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.

[0106] Examples of the hydrogen abstraction type photoradical polymerization initiator include benzophenone, 4-phenylbenzophenone, isophthalphenone, and 4-benzoyl-4'-methyl-diphenyl sulfide. As the photopolymerization initiator, a molecular cleavage type photoradical polymerization initiator and a hydrogen abstraction type photoradical polymerization initiator may be used in combination.

[0107] Commercially available photopolymerization initiators can also be used, and examples thereof include sulfonium salt-based cationic photopolymerization initiators such as "CPI-100P" manufactured by San-Apro Co., Ltd., acylphosphine oxide compounds such as "Lucirin TPO" manufactured by BASF, and "Irgacure 907," "Irgacure 819," "Irgacure 379EG," "Irgacure 184," and "Irgacure PAG290" manufactured by BASF.

[0108] 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, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and particularly preferably 3 parts by mass or more, relative to 100 parts by mass of the photopolymerizable compound. From the viewpoint of the stability over time of the pixel portion (cured product of the ink composition), the content of the photopolymerization initiator is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less, relative to 100 parts by mass of the photopolymerizable compound.

[0109] In the present ink composition, the photopolymerization initiator may be used in combination with a polymerization accelerator. Examples of the polymerization accelerator include amines that do not react with the photopolymerizable compound, such as trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, 4,4'-bis(diethylamino)benzophenone, etc. When a polymerization accelerator is used, the content thereof is preferably in the range of 1 to 100% by mass based on the total amount of the photopolymerization initiator and the polymerization accelerator.

[0110] [Antioxidants] The ink composition may further contain an antioxidant. The antioxidant is a compound that has the function of imparting excellent external quantum efficiency maintenance performance to the pixel portion. The antioxidant is not particularly limited, and examples thereof include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Among these, phenol-based antioxidants and phosphorus-based antioxidants are preferred. These antioxidants may be used alone or in combination of two or more.

[0111] Phenolic antioxidants are also commonly referred to as hindered phenolic compounds. Examples of such phenolic antioxidants include 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-hydroxybenzyl)phosphonate, thiodiethylene glycol bis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,2-dimethyl-2,3-dimethyl-2,4-dimethyl-2,5-dimethyl-2,6 ... ,6-Hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,6-hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid amide], 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)butylic acid] glycol ester, 4,4'-butylidenebis Bis(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,Examples include 1-dimethyl-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], etc. Of these, pentaerythritol tetrakis[3-[3,5-di(t-butyl)-4-hydroxyphenyl]propionate] is preferred as the phenolic antioxidant because it has excellent solubility in the ink composition.

[0112] As the phosphorus-based antioxidant, a phosphite triester compound is preferred. The phosphite triester compound may be, for example, a compound represented by the formula: P(OR 51 )(OR 52 )(OR 53 ) is a compound represented by the formula: 51 , R 52 , R 53 Each independently represents a monovalent organic group. 51 , R 52 , R 53 Two of these may be bonded to each other to form a ring structure. The monovalent organic group is preferably a monovalent hydrocarbon group, from the viewpoint of sufficiently satisfying performance requirements such as affinity with other components in the ink composition, such as the photopolymerizable compound, and maintaining excellent external quantum efficiency in the pixel portion. Examples of the monovalent hydrocarbon group include an alkyl group, an aryl group, an alkenyl group, etc. The monovalent hydrocarbon group preferably has 1 to 30 carbon atoms, and more preferably has 4 to 18 carbon atoms from the viewpoint of solubility in the ink composition.

[0113] The alkyl group may be linear or branched. Examples of the alkyl group include 2-ethylhexyl, butyl, octyl, nonyl, decyl, isodecyl, dodecyl, hexadecyl, and octadecyl groups. Examples of the aryl group include a phenyl group, a naphthyl group, a t-butylphenyl group, a di-t-butylphenyl group, an octylphenyl group, a nonylphenyl group, an isodecylphenyl group, an isodecylnaphthyl group, and the like. From the viewpoint of maintaining excellent external quantum efficiency of the pixel portion, the monovalent hydrocarbon group is preferably an alkyl group or an aryl group, and more preferably an alkyl group or a phenyl group.

[0114] R 51 , R 52 , R 53 It is preferred that at least two of R are identical to each other. 51 , R 52 , R 53 Preferably, at least one of them is a phenyl group, and more preferably, at least two of them are phenyl groups. R 51 , R 52 , R 53 It is preferable that at least one of them is a phenyl group and the other is an alkyl group (particularly, a branched alkyl group). That is, it is preferable that the phosphite triester compound has at least one phenyl group and one alkyl group. When the phosphite triester compound has the above-described functional group, it is possible to sufficiently satisfy performance requirements such as affinity with other components in the ink composition, such as the photopolymerizable compound, and to suppress a decrease in the external quantum efficiency of the pixel portion.

[0115] Examples of the compound represented by the above formula include triphenyl phosphite, 2-ethylhexyl diphenyl phosphite, and diphenyl octyl phosphite. The phosphite triester compound may be liquid or solid at room temperature (25°C). However, from the viewpoint of sufficiently satisfying performance requirements such as affinity with other components in the ink composition, such as the photopolymerizable compound, and being able to suppress a decrease in the external quantum efficiency of the pixel portion, it is preferable that the compound be liquid at room temperature (25°C). The melting point of the phosphite triester compound is preferably 20°C or lower, and more preferably 10°C or lower.

[0116] From the viewpoint of suppressing a decrease in the external quantum efficiency of the pixel portion, the content of the antioxidant in the ink composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even 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, relative to 100 parts by mass of the photopolymerizable compound. Even a small amount of antioxidant can effectively suppress a decrease in the external quantum efficiency of the pixel portion, and therefore the content of the antioxidant is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the photopolymerizable compound.

[0117] [Light scattering particles] The ink composition may further contain light-scattering particles. The light-scattering particles are, for example, optically inactive inorganic particles. When the ink composition contains light-scattering particles, it can scatter light from a light source irradiating the pixel portion, thereby achieving excellent optical properties (for example, external quantum efficiency).

[0118] Examples of materials that can be used to form light-scattering particles include: elemental metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, platinum, and gold; oxides such as silicon oxide, talc, clay, kaolin, alumina white, titanium oxide, magnesium oxide, barium oxide, aluminum oxide, bismuth oxide, zirconium oxide, and zinc oxide; carbonates such as magnesium carbonate, barium carbonate, bismuth subcarbonate, and calcium carbonate; hydroxides such as aluminum hydroxide; complex oxides such as barium zirconate, calcium zirconate, calcium titanate, barium titanate, and strontium titanate; and metal salts such as barium sulfate and bismuth subnitrate.

[0119] From the viewpoint of achieving excellent ejection stability of the ink composition (inkjet ink) and an excellent effect of improving external quantum efficiency, the light-scattering particles preferably contain at least one selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate, barium titanate, and silicon oxide, and more preferably contain at least one selected from the group consisting of titanium oxide, zirconium oxide, zinc oxide, and barium titanate.

[0120] Examples of the shape of the light-scattering particles include spherical, filamentous, and irregular shapes. However, the shape of the light-scattering particles is preferably a shape with little directionality (for example, spherical, regular tetrahedral, etc.). By using light-scattering particles of 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.

[0121] The average particle diameter (volume average diameter) of the light-scattering particles is preferably 0.05 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more, from the viewpoint of excellent ejection stability of the ink composition and excellent effect of improving external quantum efficiency. From the viewpoint of achieving 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 even more preferably 0.4 μm or less.

[0122] The average particle size of the light-scattering particles is preferably 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 0.4 μm, 0.3 to 1 μm, 0.3 to 0.6 μm, or 0.3 to 0.4 μm. In this specification, the average particle size of the light-scattering particles is measured using a dynamic light-scattering Nanotrac particle size distribution analyzer and is obtained by calculating the volume average diameter. The average particle size of the light-scattering particles used can be obtained by measuring the particle size of each particle using, for example, a transmission electron microscope or a scanning electron microscope and calculating the volume average diameter.

[0123] From the viewpoint of achieving a more excellent effect of improving the external quantum efficiency of the pixel portion, the content of the light-scattering particles in the ink composition is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 3 parts by mass or more, relative to 100 parts by mass of the total of the components other than the organic solvent contained in the ink composition. From the viewpoint of achieving excellent ejection stability of the ink composition and achieving an excellent effect of improving the external quantum efficiency of the pixel portion, the content of the light-scattering particles 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, relative to 100 parts by mass of the total of the components other than the organic solvent contained in the ink composition.

[0124] The mass ratio of the content of light-scattering particles to the content of luminescent nanoparticle composites (light-scattering particles / luminescent nanoparticle composites) is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.5 or more, from the viewpoint of achieving an excellent effect of improving the external quantum efficiency of the pixel section. The above mass ratio (light-scattering particles / luminescent nanoparticle composite) is preferably 5 or less, more preferably 2 or less, and even more preferably 1.5 or less, from the viewpoints of achieving a more excellent effect in improving the external quantum efficiency of the pixel portion and excellent continuous ejection properties (ejection stability) in the inkjet method.

[0125] From the viewpoint of easily obtaining an appropriate viscosity for an inkjet ink, the total amount of the luminescent nanoparticle composite and the light-scattering particles in the ink composition 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, per 100 parts by mass of the total of the components other than the organic solvent contained in the ink composition. From the viewpoint of easily obtaining an appropriate viscosity for an inkjet ink, the total amount of the luminescent nanoparticle complex and the light-scattering particles in the ink composition 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, per 100 parts by mass of the total of the components other than the organic solvent contained in the ink composition.

[0126] [Polymer dispersant] The ink composition may further contain a polymer dispersant, which is preferably a polymer compound having a weight-average molecular weight of 750 or more and having a functional group that has affinity for the light-scattering particles. The polymer dispersant functions to stably disperse the light-scattering particles in the ink composition. This polymer dispersant adsorbs to the light-scattering particles via functional groups that have affinity for the light-scattering particles, and disperses the light-scattering particles in the ink composition due to electrostatic and / or steric repulsion between the polymer dispersants.

[0127] When the ink composition contains a polymer dispersant, the light-scattering particles can be dispersed well even when the content of the light-scattering particles is relatively high (for example, about 60% by mass). The polymer dispersant is preferably bound to the surface of the light-scattering particles, although the polymer dispersant may be bound to the surface of the luminescent nanoparticle composite or may be free in the ink composition. The functional group having an affinity for the light-scattering particles includes an acidic functional group, a basic functional group, and a nonionic functional group. The acidic functional group has a dissociable proton and may be neutralized with a base such as an amine or hydroxide ion, while the basic functional group may be neutralized with an acid such as an organic acid or an inorganic acid.

[0128] Examples of acidic functional groups include carboxyl group (-COOH), sulfo group (-SO3H), sulfate group (-OSO3H), phosphonic acid group (-PO(OH)3), phosphoric acid group (-OPO(OH)3), phosphinic acid group (-PO(OH)-), and mercapto group (-SH). Examples of 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. Examples of nonionic functional groups include a hydroxy group, an ether group, a thioether group, a sulfinyl group (-SO-), a sulfonyl group (-SO2-), a carbonyl group, a formyl group, an ester group, a carbonate ester group, an amide group, a carbamoyl group, a ureido group, a thioamide group, a thioureido group, a sulfamoyl group, a cyano group, an alkenyl group, an alkynyl group, a phosphine oxide group, and a phosphine sulfide group.

[0129] The polymer dispersant may be a polymer (homopolymer) of a single monomer, or a copolymer (copolymer) of multiple types of monomers. The polymeric dispersant may be a random copolymer, a block copolymer, or a graft copolymer. 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, phenolic resins, silicone resins, polyurea resins, amino resins, epoxy resins, polyamines such as polyethyleneimine and polyallylamine, and polyimides.

[0130] Commercially available polymer dispersants can also be used, such as the Ajisper PB series manufactured by Ajinomoto Fine-Techno Co., Ltd., the DISPER BYK series manufactured by BYK, and the Efka series manufactured by BASF.

[0131] [Zinc compounds] The ink composition may further contain a zinc compound having zinc as a central metal and two ligands coordinated to the zinc. Preferably, the zinc compound has one zinc atom and the zinc has a divalent valence. When the ink composition further contains such a zinc compound, the wavelength shift of converted light in the pixel section (the phenomenon in which the wavelength of converted light emitted from the pixel section shifts to a longer wavelength side than the emission wavelength of the luminescent nanoparticle composite) can be reduced.

[0132] In this zinc compound, the two ligands each have a sulfur atom, and are coordinated to zinc by directly bonding (e.g., ionic bonding) to the zinc. The two ligands may be the same or different. The molecular weight of the zinc compound is preferably 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 better. The molecular weight of the zinc compound may be 600 or less, or may be 500 or less. Furthermore, the molecular weight of the zinc compound may be 200 or more from the viewpoints of easily increasing the solubility in the ink composition and easily obtaining the effect of reducing wavelength shift.

[0133] The ligand is preferably a compound having a coordinating functional group containing a sulfur atom. Such a ligand is coordinated to zinc by directly bonding the sulfur atom of the coordinating functional group to zinc. Examples of the coordinating functional group include a thiol group (mercapto group), a dithiocarbamic acid group, a dithiocarboxylic acid group, and a thiocarboxylic acid group. These coordinating functional groups may, for example, be deprotonated and bound to zinc, i.e., the ligands may be coordinated to zinc in an ionized state.

[0134] Examples of the compound having a coordinating functional group include dithiocarbamic acids such as monoalkyldithiocarbamic acid, dialkyldithiocarbamic acid, diaryldithiocarbamic acid, alkylaryldithiocarbamic acid, and diaralkyldithiocarbamic acid; mercaptopyridines such as 2-mercaptopyridine N-oxide; mercaptobenzothiazoles such as 2-mercaptobenzothiazole; and mercaptobenzoxazoles such as 2-mercaptobenzoxazole. From the viewpoints of further improving external quantum efficiency, further improving photostability, and achieving a more significant effect of reducing wavelength shift, it is preferable that at least one of the two ligands is a dithiocarbamic acid (a compound having a dithiocarbamic acid group as a coordinating functional group), and it is more preferable that both of the two ligands are dithiocarbamic acids (compounds having a dithiocarbamic acid group as a coordinating functional group).

[0135] Specific examples of the zinc compound include zinc bis(2-hydroxyethyl)dithiocarbamate, zinc bis(2-mercaptopyridine N-oxide), zinc (toluene-3,4-dithiolato), zinc bis(dibenzyldithiocarbamate), zinc bis(dibutyldithiocarbamate), zinc bis(diethyldithiocarbamate), zinc bis(N-ethyl-N-phenyldithiocarbamate), and zinc bis(2-mercaptobenzothiazole). Commercially available products may also be used, such as "Noccela BZ" manufactured by Ouchi Shinko Chemical Industry Co., Ltd. and "Zinc Pyrithione" manufactured by Tokyo Chemical Industry Co., Ltd.

[0136] From the viewpoint of further improving the external quantum efficiency, further improving the photostability, and more significantly reducing the wavelength shift, the content of the zinc compound is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the total of the components other than the organic solvent contained in the ink composition. From the same viewpoint, the content of the zinc compound is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of the total of all components other than the organic solvent contained in the ink composition.

[0137] [Organic solvents] 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, diethyl succinate, 1,4-butanediol diacetate, and glyceryl triacetate.

[0138] The boiling point of the organic solvent is preferably 150° C. or higher, and more preferably 180° C. or higher, from the viewpoint of continuous ejection stability of the ink composition (inkjet ink). Furthermore, when forming pixel portions, it is necessary to remove the organic solvent from the ink composition before curing the ink composition. Therefore, from the viewpoint of facilitating removal of the organic solvent, it is preferable that the boiling point of the organic solvent is 300°C or less.

[0139] 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, allowing the luminescent nanoparticle composite to exhibit excellent luminescence 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, and dipropylene glycol methyl ether acetate; diacetate compounds such as 1,4-butanediol diacetate and propylene glycol diacetate; and glyceryl triacetate.

[0140] In the ink composition of this embodiment, the photopolymerizable compound also functions as a dispersion medium, making it possible to disperse light-scattering particles and luminescent nanoparticle composites without using a solvent, which has the advantage of eliminating the need for a step of removing the organic solvent by drying when forming pixel portions.

[0141] The ink composition may further contain components other than the above-described components, such as additives such as ultraviolet absorbers, surface tension adjusters, anti-fading agents, and conductive salts, as long as the effects of the present invention are not impaired.

[0142] From the viewpoint of ejection stability, the viscosity of the ink composition during ejection may be 2 mPa·s or more, 5 mPa·s or more, or 7 mPa·s or more, or 20 mPa·s or less, 15 mPa·s or less, or 12 mPa·s or less. The viscosity of the ink composition when ejected is preferably 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, 7 to 20 mPa·s, 7 to 15 mPa·s, or 7 to 12 mPa·s. In this specification, the viscosity of the ink composition when it is ejected is a value measured using an E-type viscometer at the same temperature as when it is ejected.

[0143] When the viscosity of the ink composition when ejected 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 stable, making it easier to control the ejection of the ink composition (for example, control of the ejection amount and ejection timing). On the other hand, if the viscosity of the ink composition when ejected is 20 mPa·s or less, the ink composition can be smoothly ejected from the ink ejection holes.

[0144] The surface tension of the ink composition is preferably a surface tension suitable for inkjet ink, specifically, preferably 20 to 40 mN / m, more preferably 25 to 35 mN / m. Adjusting the surface tension within this range facilitates ejection control of the ink composition (for example, control of the ejection amount and ejection timing) and can also suppress the occurrence of deflected flight. The deflection of ink droplets refers to the occurrence of a deviation of 30 μm or more in the landing position of an ink composition when the ink composition is ejected from an ink ejection orifice relative to the target position.

[0145] When the surface tension is 40 mN / m or less, the meniscus shape of the ink composition at the tip of the ink ejection orifice is stable, making it easy to control the ejection of the ink composition (for example, control of the ejection amount and ejection timing). On the other hand, when the surface tension is 20 mN / m or more, contamination of the periphery of the ink ejection hole with the ink composition can be prevented, thereby suppressing the occurrence of deflected ink flight. In other words, it is possible to prevent the ink composition from landing accurately in the pixel formation region where it is intended to land, resulting in pixel portions that are insufficiently filled with the ink composition, or the ink composition from landing in a pixel formation region (or pixel portion) adjacent to the pixel formation region where it is intended to land, resulting in reduced color reproducibility. In this specification, the surface tension of the ink composition is a value measured at 23° C. using the ring method (also called the ring method).

[0146] When the ink composition of this embodiment is used as an inkjet ink, it is preferably applied to a piezoelectric inkjet recording device. In the piezoelectric 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 the desired luminescence characteristics can be more easily obtained in the pixel area (light conversion layer). Although one embodiment of the ink composition has been described above, the ink composition of the above-described embodiment 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.

[0147] When the ink composition is used in a photolithography method, the ink composition is first applied to a substrate and then dried to form a coating film. The resulting coating film is soluble in an alkaline developer and is patterned by treatment with the alkaline developer. In this case, an aqueous solution is preferably used as the alkaline developer from the viewpoint of ease of waste liquid treatment, and therefore the coating film of the ink composition is treated with the aqueous solution. On the other hand, in the case of an ink composition using a luminescent nanoparticle composite (such as quantum dots), the luminescent nanoparticle composite is unstable in water, and the luminescent properties (e.g., fluorescent properties) may be impaired by moisture. The ink composition of the present invention is preferably used in an inkjet method, which does not require treatment with an alkaline developer (aqueous solution).

[0148] Furthermore, even if 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 will be prone to absorbing moisture from the atmosphere, which may impair the luminescence properties (e.g., fluorescence properties) of the luminescent nanoparticle composites (quantum dots, etc.) over time. From the viewpoint of more reliably reducing the occurrence of problems due to water absorption, in this embodiment, the coating film of the ink composition is preferably alkali-insoluble. That is, the ink composition of this embodiment is preferably an ink composition that can form an alkali-insoluble coating film.

[0149] Such an ink composition can be obtained by using an alkali-insoluble photopolymerizable compound as the photopolymerizable compound. Here, the coating film of the ink composition being alkali-insoluble means that the amount of the coating film of the ink composition that dissolves in a 1% by mass aqueous solution of potassium hydroxide at 25°C is 30% by mass or less, based on the total mass of the coating film of the ink composition. The dissolution amount is preferably 10% by mass or less, and more preferably 3% by mass or less. Whether the ink composition is capable of forming an alkali-insoluble coating film can be confirmed by measuring the amount of dissolution in a 1 μm-thick coating film obtained by applying the ink composition to a substrate and drying it at 80°C for 3 minutes.

[0150] <Method of manufacturing ink composition> The ink composition of this embodiment is prepared, for example, by mixing the above-described components (the luminescent nanoparticle composite, the photopolymerizable compound, and other optional components). The method for producing an 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.

[0151] 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 a second step of mixing the dispersion of light-scattering particles with a luminescent nanoparticle composite. The dispersion of light-scattering particles may further contain a polymer dispersant. In this method, the dispersion of light-scattering particles may further contain a photopolymerizable compound, and the photopolymerizable compound may further be mixed in the second step. According to the above method, the light-scattering particles can be sufficiently dispersed, which makes it possible to improve the optical properties (e.g., external quantum efficiency) of the pixel portion and to easily obtain an ink composition with excellent ejection stability.

[0152] In the first step, a dispersion of light-scattering particles may be prepared by mixing light-scattering particles and, if necessary, a polymer dispersant and a photopolymerizable compound, and then performing a dispersion treatment. The mixing and dispersion treatment can be carried out using a dispersing device such as a bead mill, a paint conditioner, a planetary mixer, a jet mill, etc. From the viewpoints of improving the dispersibility of the light-scattering particles and facilitating the adjustment of the average particle size of the light-scattering particles to a desired range, it is preferable to use a bead mill or a paint conditioner. Furthermore, by mixing the light-scattering particles with a polymeric dispersant before mixing the light-scattering particles with the luminescent nanoparticle composite, the light-scattering particles can be more thoroughly dispersed, which makes it easier to obtain excellent discharge stability and excellent external quantum efficiency.

[0153] The method for producing an ink composition may further include a step of preparing a dispersion of a luminescent nanoparticle composite containing a luminescent nanoparticle composite and a photopolymerizable compound before the step 2. In this case, in the step 2, the dispersion of light-scattering particles and the dispersion of the luminescent nanoparticle composite are mixed. In the step of preparing a dispersion of a luminescent nanoparticle composite, the dispersion of a luminescent nanoparticle composite may be prepared by mixing the luminescent nanoparticle composite with a photopolymerizable compound and carrying out a dispersion treatment.

[0154] The mixing and dispersion treatment can be carried out using a dispersing device such as a bead mill, a paint conditioner, a planetary mixer, a jet mill, etc. From the viewpoints of improving the dispersibility of the luminescent nanoparticle composite and facilitating the adjustment of the average particle size of the luminescent nanoparticle composite to a desired range, it is preferable to use a bead mill, a paint conditioner, or a jet mill. This method allows the luminescent nanoparticle composite to be sufficiently dispersed, thereby improving the optical properties of the pixel portion (e.g., external quantum efficiency) and easily producing an ink composition with excellent ejection stability.

[0155] In the above-mentioned production method, when other components such as an antioxidant or an organic solvent are blended, these components may be mixed into the dispersion of the luminescent nanoparticle composite, the dispersion of the light-scattering particles, or a mixed dispersion obtained by mixing the dispersion of the luminescent nanoparticle composite and the dispersion of the light-scattering particles.

[0156] <Ink composition set> An ink composition set of one embodiment includes the ink composition of the above-described embodiment. The ink composition set may also include an ink composition that does not contain a luminescent nanoparticle composite (non-luminescent ink composition), in addition to the ink composition of the above-described embodiment (luminescent ink composition). The non-luminous ink composition may be, for example, a conventionally known ink composition, and may have the same composition as the ink composition (luminous ink composition) of the above-described embodiment, except that the non-luminous ink composition does not contain a luminous nanoparticle composite.

[0157] The non-luminous ink composition does not contain a luminous nanoparticle composite. Therefore, when light is incident on a pixel portion formed using the non-luminous ink composition (a pixel portion containing a cured product of the non-luminous ink composition), the light emitted from the pixel portion has approximately the same wavelength as the incident light. Therefore, the non-luminous ink composition is suitable for forming pixel portions of 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 portions formed by the non-luminous ink composition will be blue pixel portions.

[0158] The non-luminous ink composition preferably contains light-scattering particles. When the non-luminous ink composition contains light-scattering particles, the pixel portion formed by the non-luminous ink composition can scatter incident light. This can reduce the difference in light intensity of the light emitted from the pixel portion depending on the viewing angle.

[0159] <Light conversion layer and color filter> Next, the light conversion layer and color filter obtained using the ink composition set of the above-described embodiment will be described in detail with reference to the drawings. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and duplicated descriptions will be omitted. 1 is a schematic cross-sectional view of a color filter according to one embodiment of the present invention. Hereinafter, for convenience of explanation, the upper side in FIG. 1 will also be referred to as "top" or "upper side," and the lower side will also be referred to as "bottom" or "lower side." 1 includes a substrate 40 and a light conversion layer 30 provided on the substrate 40. The light conversion layer 30 includes a plurality of pixel units 10 and a light-shielding unit 20.

[0160] The light conversion layer 30 has a first pixel portion 10a, a second pixel portion 10b, and a third pixel portion 10c as the pixel portion 10. The first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c are arranged in a lattice pattern, repeating in this order. The light-shielding portions 20 are provided between adjacent pixel portions 10, i.e., 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, the adjacent pixel portions 10 are separated by the light-shielding portions 20.

[0161] The first pixel portion 10a and the second pixel portion 10b are luminescent pixel portions (luminescent pixel portions) containing a luminescent nanoparticle composite, a curable component, and light-scattering particles. At least one of the first pixel portion 10a and the second pixel portion 10b contains a cured product of the ink composition described above. 1, the first pixel portion 10a includes a first curing component 13a, and first luminescent nanoparticle composites 11a and first light-scattering particles 12a dispersed in the first curing component 13a. 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.

[0162] The curable component is a component obtained by polymerization of a photopolymerizable compound, and may include a polymer of the photopolymerizable compound and organic components in the ink composition (such as a polymer dispersant and an unreacted photopolymerizable compound). 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 as or different from each other, and the first light-scattering particles 12a and the second light-scattering particles 12b may be the same as or different from each other.

[0163] 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 portion 10a can be said to be a red pixel portion for converting blue light into red light. Second luminescent nanoparticle composite 11b is a green luminescent 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 500 to 560 nm. That is, second pixel portion 10b can be said to be a green pixel portion for converting blue light into green light.

[0164] From the viewpoint of achieving a superior effect of improving external quantum efficiency and obtaining excellent luminescence intensity, the content of the luminescent nanoparticle composite in the luminescent pixel portion is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, particularly preferably 20% by mass or more, and most preferably 30% by mass or more, based on the total mass of the cured product of the luminescent ink composition. From the viewpoint of achieving excellent reliability in the pixel portion and excellent luminescence intensity, the content of the luminescent nanoparticle composite is preferably 80 mass % or less, more preferably 75 mass % or less, even more preferably 70 mass % or less, and particularly preferably 60 mass % or less, based on the total mass of the cured product of the luminescent ink composition.

[0165] From the viewpoint of achieving a more excellent effect of improving external quantum efficiency, the content of the light-scattering particles in the luminescent pixel portion is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 3% by mass or more, based on the total mass of the cured product of the luminescent ink composition. From the viewpoint of achieving a superior effect in improving external quantum efficiency and superior reliability of the pixel portion, the content of the light-scattering particles is preferably 60% by mass or less, more preferably 50% by mass or less, even 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 most preferably 15% by mass or less, based on the total mass of the cured product of the luminescent ink composition.

[0166] 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 a luminous nanoparticle composite, but contains light-scattering particles and a curable 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.

[0167] The third pixel unit 10c preferably has a transmittance of 30% or more for light in the wavelength range of 420 to 480 nm, for example. In this case, if a light source that emits light in the wavelength range of 420 to 480 nm is used, the third pixel unit 10c can function as a blue pixel unit. The transmittance of the third pixel portion 10c can be measured by a microspectrometer.

[0168] From the viewpoint of further reducing the difference in light intensity at different viewing angles, the content of light-scattering particles in the third pixel portion (non-luminous pixel portion) 10c is preferably 1 mass % or more, more preferably 3 mass % or more, and even more preferably 5 mass % or more, based on the total mass of the cured product of the non-luminous ink composition. From the viewpoint of further reducing light reflection, the content of the light-scattering particles is preferably 80 mass % or less, more preferably 75 mass % or less, and even more preferably 70 mass % or less, based on the total mass of the cured product of the non-luminous ink composition.

[0169] The thickness of the pixel portion (first pixel portion 10a, second pixel portion 10b, and third pixel portion 10c) is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more. The thickness of the pixel portion (first pixel portion 10a, second pixel portion 10b, and third pixel portion 10c) is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less.

[0170] The light-shielding portion 20 is a partition portion (black matrix) provided to separate adjacent pixel portions to prevent color mixing (crosstalk) and to prevent leakage of light from the light source. The constituent material of the light-shielding portion 20 is not particularly limited, but examples include metals such as chromium, as well as resin compositions containing binder resins and light-shielding particles such as carbon microparticles, metal oxides, inorganic pigments, and organic pigments. Examples of binder resins that can be used include resins containing one or more of polyimide resin, acrylic resin, epoxy resin, polyacrylamide, polyvinyl alcohol, gelatin, casein, cellulose, etc., photosensitive resins, and O / W emulsion resins (e.g., reactive silicone emulsions). The thickness of the light-shielding portion 20 is preferably 1 to 30 μm.

[0171] The substrate 40 is a transparent substrate that is optically transparent. For example, a transparent glass substrate made of quartz glass, Pyrex (registered trademark) glass, synthetic quartz, or the like, a transparent flexible substrate such as a transparent resin film, or an optical resin film can be used as the substrate 40. Among these, it is preferable to use a glass substrate made of alkali-free glass that does not contain any alkali components in the glass. Specific examples of alkali-free glass include Corning's "7059 Glass," "1737 Glass," "Eagle 200," and "Eagle XG," AGC's "AN100," and Nippon Electric Glass's "OA-10G" and "OA-11." These are materials with a small coefficient of thermal expansion, and are excellent in dimensional stability and workability during high-temperature heat treatment.

[0172] The color filter 100 having the above-described light conversion layer 30 can be suitably used in combination with a light source that emits light with a wavelength in the range of 420 to 480 nm.

[0173] The color filter 100 can be manufactured, for example, by forming a pattern of light-shielding portions 20 on a substrate 40, and then forming pixel portions 10 in the pixel portion formation areas partitioned by the light-shielding portions 20 on the substrate 40. The pixel portion 10 can be formed by a method comprising the steps of selectively depositing an ink composition (inkjet ink) onto the pixel portion formation region on the substrate 40 by an inkjet method, and irradiating the ink composition with active energy rays (e.g., ultraviolet rays) to cure the ink composition. When the above-mentioned luminous ink composition is used as the ink composition, a luminous pixel portion is obtained, and when a non-luminous ink composition is used, a non-luminous pixel portion is obtained.

[0174] The light-shielding portion 20 can be formed in the area that forms the boundary between multiple pixel portions on one surface of the substrate 40 by patterning a thin metal film such as chromium or a thin film of a resin composition containing light-shielding particles. The metal thin film can be formed by, for example, a sputtering method, a vacuum deposition method, etc. Furthermore, the thin film of the resin composition containing the light-shielding particles can be formed by, for example, a coating method, a printing method, etc. The patterning method may be photolithography.

[0175] Examples of inkjet methods include a bubble jet (registered trademark) method using an electrothermal converter 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 a portion of the organic solvent during drying, and it is more preferable to remove all of the organic solvent. The ink composition is preferably dried under reduced pressure (vacuum drying), which is usually carried out at a pressure of 1.0 to 500 Pa at 20 to 30° C. for 3 to 30 minutes in order to control the composition of the ink composition.

[0176] The ink composition can be cured using, for example, a mercury lamp, a metal halide lamp, a xenon lamp, an LED, or the like. The wavelength of the light to be irradiated is preferably 200 to 440 nm, and the exposure dose is preferably 10 to 4000 mJ / cm. 2 It is preferable that:

[0177] When the cured product is subjected to heat treatment (post-baking) to reduce outgassing by removing unreacted materials and improve adhesion by thermal crosslinking, the heating temperature is preferably 110 to 250° C. The heating time is preferably 10 to 120 minutes.

[0178] Although an embodiment of the light conversion layer and color filter, as well as the manufacturing method thereof, has been described above, the present invention is not limited to this. For example, the light conversion layer may have a pixel portion (blue pixel portion) containing a cured product of a luminescent ink composition containing a blue luminescent nanoparticle composite, instead of or in addition to the third pixel portion 10c. The light conversion layer may also have pixel portions (e.g., yellow pixel portions) containing a cured product of a luminescent ink composition containing a luminescent nanoparticle composite that emits light of a color other than red, green, or blue. In this case, it is preferable that each of the luminescent nanoparticle composites contained in each pixel portion of the light conversion layer has a maximum absorption wavelength in the same wavelength range.

[0179] Furthermore, at least a part of the pixel portion 10 of the light conversion layer 30 may be configured to include a cured product of a composition containing a pigment other than the luminescent nanoparticle composite. Furthermore, the color filter 100 may have an ink-repellent layer on the light-shielding portion 20 that is narrower than the light-shielding portion 20 and is made of an ink-repellent material. Furthermore, instead of providing an ink-repellent layer, a photocatalyst-containing layer as a wettability-variable layer may be formed in a solid state in the region including the pixel portion formation region, and then the photocatalyst-containing layer may be exposed to light through a photomask to selectively increase the ink affinity (wettability) of the pixel portion formation region. Examples of photocatalysts include titanium oxide and zinc oxide.

[0180] The color filter 100 may include an ink-receiving layer between the substrate 40 and the pixel portion 10, the ink-receiving layer containing hydroxypropyl cellulose, polyvinyl alcohol, gelatin, or the like. The color filter may also have a protective layer on the pixel portion 10. This protective layer is provided to flatten the color filter and to prevent the components contained in the pixel portion 10 and the components contained in the photocatalyst-containing layer from eluting into other layers. As the material for forming the protective layer, a known material used as the protective layer for the color filter 100 can be used.

[0181] Furthermore, in manufacturing the light conversion layer 30 and the color filter 100, the pixel portion may be formed by photolithography instead of the inkjet method. In this case, first, the ink composition is applied in a layer form on the substrate 40 to form an ink composition layer. Next, the ink composition layer is exposed to light in a predetermined pattern and then developed using a developer. This forms pixel portions 10 made of a cured product of the ink composition. Since the developer is usually alkaline, an alkali-soluble material is used as the material for the ink composition. However, in terms of material usage efficiency, the inkjet method is superior to the photolithography method. This is because, in principle, the photolithography method removes more than two-thirds of the material, resulting in waste. For this reason, in this embodiment, it is preferable to use the ink composition as an inkjet ink and form pixel portions by the inkjet method.

[0182] Furthermore, the pixel portion 10 of the light conversion layer 30 of this embodiment may further contain, in addition to the above-mentioned luminescent nanoparticle composite, a pigment of approximately the same color as the luminescent color of the luminescent nanoparticle composite. To incorporate the pigment into the pixel portion 10, the pigment may be mixed into the ink composition.

[0183] In addition, one or two of the red light-emitting pixel portion (R), green light-emitting pixel portion (G) and blue light-emitting pixel portion (B) in the light conversion layer 30 of this embodiment may be pixel portions that do not contain a light-emitting nanoparticle composite but contain a colorant. Usable coloring materials include, for example, diketopyrrolopyrrole pigments and / or anionic red organic dyes for the red-emitting pixel portion (R). The green-emitting pixel portion (G) includes at least one selected from the group consisting of halogenated copper phthalocyanine pigments, phthalocyanine green dyes, and mixtures of phthalocyanine blue dyes and azo yellow organic dyes. The blue-emitting pixel portion (B) includes ε-type copper phthalocyanine pigments and / or cationic blue organic dyes. When mixed into the light conversion layer 30, the amount of these coloring materials used is preferably 1 to 5 mass % 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. [Example]

[0184] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples. The compounds used in the present examples are shown below.

[0185] <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: Fancryl FA-512AS, manufactured by Showa Denko Materials Co., Ltd.) DCPEM: Dicyclopentenyloxyethyl methacrylate (Product name: Fancryl FA-512MT, manufactured by Showa Denko Materials Co., Ltd.) AOMA: 2-(allyloxymethyl)methyl acrylate (Product name: "AOMA", manufactured by Nippon Shokubai Co., Ltd.) <Photopolymerization initiator> TPO-H: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Product name: Omnirad TPO-H, manufactured by IGM Resins BV) 819:Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Product name: Omnirad 819, manufactured by IGM Resins BV) <Zinc compounds> ZDBC: Zinc dibutyldithiocarbamate (Product name: Noccela BZ-P, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) <Antioxidants> 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.)

[0186] <Luminescent nanoparticles> The 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 a reaction flask and then heated at 140° C. under vacuum for 2 hours. Then, under a nitrogen atmosphere, the temperature of the mixture was raised to 250° C. 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. Next, 8 ml of toluene and 20 ml of ethanol were added to the reaction solution in the glove box. The mixture was then centrifuged, and the supernatant was decanted to obtain InP nanoparticles. The resulting InP nanoparticles were then dispersed in ODE, thereby obtaining a dispersion containing 5 mass % of InP nanoparticles (ODE dispersion).

[0187] (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 heated at 120°C under vacuum for 2 hours to prepare 0.4 M zinc precursor solution 1. (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. under vacuum for 30 minutes. Next, the temperature was raised to 200°C under a nitrogen atmosphere, and then 3 mL of the 0.4 M zinc precursor solution 1 obtained in (2-1) above and 0.8 mL of 1.0 M trioctylphosphine selenide (TOPSe) were added to the reaction flask, and the mixture was kept 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, and 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. Next, 8 ml of toluene and 20 ml of ethanol were added to the reaction solution. Subsequently, the solution was centrifuged, and the supernatant was decanted to obtain luminescent nanoparticles 1 with a core-shell structure (InP / ZnSe / ZnS) containing In and P in the core and ZnSe and ZnS shells.

[0188] <Organic Ligand> Carboxylic Acids 1 to 16 as carboxylic acid compounds were prepared as follows.

[0189] Carboxylic acid 1: 18 g (110 mmol) of diethylene glycol monophenyl ether, manufactured by Tokyo Chemical Industry Co., Ltd., 10 g (100 mmol) of succinic anhydride, 11 g (110 mmol) of triethylamine, and 50 g of toluene were added to a reaction flask, and the mixture was stirred at room temperature under a nitrogen atmosphere for 3 hours. 50 g of ethyl acetate was added to the reaction solution, which was then washed once with 100 mL of 1N hydrochloric acid and twice with saturated brine. The organic layer was dried over magnesium sulfate and concentrated to give 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 (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 in the production of carboxylic acid 1, using 110 mmol of diethylene glycol monobenzyl ether (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 in the production of carboxylic acid 1, using 110 mmol of diethylene glycol monobenzyl ether (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 in the production of carboxylic acid 1, using 110 mmol of ethylene glycol monobenzyl ether (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 in the production of carboxylic acid 1, using 110 mmol of propylene glycol monophenyl ether (manufactured by 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 in the production of carboxylic acid 1, using 110 mmol of tetrahydrofurfuryl alcohol (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 in the production of carboxylic acid 1, using 110 mmol of glycerol formal (Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric anhydride, 110 mmol of triethylamine, and 50 g of toluene. Carboxylic acid 9: 19 g (100 mmol) of phenoxyethyl acrylate, manufactured by Tokyo Chemical Industry Co., Ltd., 11 g (105 mmol) of 3-mercaptopropionic acid, 11 g (110 mmol) of triethylamine, and 50 g of toluene were added to a reaction flask, and the mixture was stirred at 80° C. for 6 hours under a nitrogen atmosphere. 50 g of ethyl acetate was added to the reaction solution, which was then washed once with 100 mL of 1N hydrochloric acid and twice with saturated brine. The organic layer was dried over magnesium sulfate and concentrated to give carboxylic acid 9. Carboxylic Acid 10: Carboxylic acid 10 was obtained in the same manner as in the production of carboxylic acid 9, using 100 mmol of tetrahydrofurfuryl acrylate (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 (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 in the production of carboxylic acid 1, using 110 mmol of polyethylene glycol monomethyl ether having a number average molecular weight of 350 (manufactured by Merck), 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 (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 in the production of carboxylic acid 1, using 110 mmol of hexaethylene glycol monobenzyl ether (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 obtained in the same manner as in the production of carboxylic acid 1, using 110 mmol of triethylene glycol monomethyl ether (Tokyo Chemical Industry Co., Ltd.), 100 mmol of cis-1,2-cyclohexanedicarboxylic anhydride glutaric anhydride, 110 mmol of triethylamine, and 50 g of toluene. Carboxylic acid 16: Carboxylic acid 16 was obtained in the same manner as in the production of carboxylic acid 1, using 110 mmol of diethylene glycol monophenyl ether (Tokyo Chemical Industry Co., Ltd.), 100 mmol of cis-1,2-cyclohexanedicarboxylic anhydride glutaric anhydride, 110 mmol of triethylamine, and 50 g of toluene. The chemical structural formulas of the obtained carboxylic acids 1 to 16 are shown below.

[0190] [ka]

[0191] [Production of luminescent nanoparticle composites] [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 a reaction flask, and then the mixture was stirred at 80° C. for 3 hours under a nitrogen atmosphere. After the reaction solution was cooled to room temperature, 10 ml of acetone and 60 ml of heptane were added to reprecipitate the product, followed by centrifugation and decanting the supernatant to obtain luminescent nanoparticle conjugate A-1.

[0192] [Examples 2 to 10, Comparative Examples 1 to 6] Luminescent nanoparticle complexes A-2 to A-10 and B-1 to B-4 were obtained 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. Note that reprecipitation was not possible, and no luminescent nanoparticle composites were obtained, in Comparative Examples 5 and 6. It is thought that carboxylic acids 15 and 16, which have a substituent at the α-position of the carboxy group, could not be reprecipitated in an acetone-heptane mixed solvent because the ligand exchange reaction did not proceed sufficiently due to steric hindrance caused by the substituent. Table 1 also shows the δD values ​​of the Hansen solubility parameters and molecular weights of the organic ligands used. The Hansen solubility parameter δD value was estimated using HSPiP. The number average molecular weight of the organic ligand with molecular weight distribution is 1 It was calculated from the integral ratio of HNMR.

[0193] [Table 1]

[0194] <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 Kaisha, Ltd., average particle size (volume average diameter): 210 nm), 1.0 g of a polymer dispersant (Ajisper PB-821, manufactured by Ajinomoto Fine-Techno Co., Inc.), and 26.0 g of 1,4-butanediol diacrylate were mixed. Zirconia beads (diameter: 1.25 mm) were then added to the resulting mixture, and the mixture was dispersed by shaking for 2 hours using a paint conditioner. The zirconia beads were then removed using a polyester mesh filter to obtain a light-scattering particle dispersion (titanium oxide content: 55% by mass).

[0195] 1. Preparation of Ink Composition <Ink composition 1> Luminescent nanoparticle composite A-1, a photopolymerizable compound, a photopolymerization initiator, a light-scattering particle dispersion, and an antioxidant were blended so that the content of each component was the amount shown in Table 2 (unit: parts by mass), and the mixture was mixed uniformly in a container filled with argon gas. The mixture was then filtered through a filter with a pore size of 5 μm in a glove box. Further, argon gas was introduced into the container containing the obtained filtrate, and the inside of the container was saturated with argon gas. The pressure was then reduced to remove the argon gas, thereby obtaining ink composition 1.

[0196] <Ink compositions 2 to 20> Each luminescent nanoparticle composite was mixed with a photopolymerizable compound, a photopolymerization initiator, a light-scattering particle dispersion, a dithiocarbamic acid compound, and an antioxidant so that the content of each component was the amount shown in Table 2 (unit: parts by mass), and ink compositions 2 to 20 were obtained in the same manner as ink composition 1.

[0197] 2. Evaluation of ink composition 2-1. Preparation of samples for evaluating external quantum efficiency Each ink composition was applied to a glass substrate in the atmosphere using a spin coater so as to give a film thickness of 10 μm. The coating film was exposed to a UV irradiation device using an LED lamp with a dominant wavelength of 395 nm under a nitrogen atmosphere at an integrated light dose of 1000 mJ / cm 2 The ink composition was cured by irradiating it with UV light so that the cured ink composition was cured to form a layer (light conversion layer) on the glass substrate. In this way, a sample for evaluation was prepared, which was a substrate having a light conversion layer.

[0198] 2-2.External quantum efficiency (EQE) measurement The surface-emitting light source used was a blue LED (manufactured by CCS Inc.) that emits light with an emission peak at a wavelength of 450 nm. The measurement device was a radiation spectrophotometer (manufactured by Otsuka Electronics Co., Ltd., "MCPD-9800") connected to an integrating sphere, with the integrating sphere placed above the blue LED. Each evaluation sample prepared in 2-1 was inserted between the blue LED and the integrating sphere, and the blue LED was turned on to measure the observed spectrum and illuminance at each wavelength.

[0199] From the spectrum and illuminance measured by the above measurement device, the external quantum efficiency (EQE) was calculated as follows. EQE is a value that indicates the percentage of light (photons) incident on the light conversion layer that is emitted as fluorescence toward the observer. Therefore, a large EQE value indicates that the light conversion layer has excellent luminescence properties, and is an important evaluation index. EQE(%)=P1(Green) / E(Blue)×100

[0200] Here, E (Blue) and P1 (Green) represent the following values, respectively. 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 observed photons. Note that h is Planck's constant and c is the speed of light.

[0201] 2-3. Heat resistance Each evaluation sample prepared in 2-1 was transferred to a hot plate at 180°C placed in a glove box under a nitrogen atmosphere and heated for 30 minutes. After the evaluation sample was cooled to room temperature, the EQE was measured in the same manner as in 2-2. The EQE retention rate was calculated using the following formula, and the heat resistance was evaluated according to the following criteria. Retention rate = [EQE after heating] / [EQE before heating] x 100 [Evaluation criteria] ◎: 98% or more 〇: 95% or more, less than 98% △: 90% or more, less than 95% ×: Less than 90%

[0202] 2-4. Atmospheric storage stability (atmospheric stability) Each evaluation sample prepared in 2-3 was left in the atmosphere under the lighting of a yellow room for 24 hours, and then the EQE was measured in the same manner as in 2-2. The maintenance rate of the EQE after irradiation to the EQE before irradiation was calculated using the following formula, and the atmospheric stability was evaluated according to the following criteria. Maintenance rate = [EQE after 24 hours] / [initial EQE] x 100 [Evaluation criteria] ◎: 98% or more 〇: 95% or more, less than 98% △: 90% or more, less than 95% ×: Less than 90%

[0203] 2-5. Viscosity of ink composition The viscosity of the ink composition prepared in 1 at 40°C was measured using an E-type viscometer, and the viscosity was evaluated according to the following criteria. [Evaluation criteria] ◎: 12mPa·s or less 〇: Exceeding 12mPa·s, below 13mPa·s △: Exceeding 13mPa·s, 14mPa·s or less ×: Exceeding 14mPa·s

[0204] 2-6. Storage stability of ink composition The ink composition prepared in 1 was stored for 2 weeks in a thermostatic tester maintained at 40°C, and then the viscosity of the ink composition was measured, and the viscosity increase rate of the ink composition was calculated using the following formula, and the storage stability was evaluated according to the following criteria. Viscosity increase rate = ([Viscosity after 2 weeks] - [Initial viscosity]) / [Initial viscosity] x 100 [Evaluation criteria] ◎: Viscosity increase of 3% or less 〇: Viscosity increase is over 3% and 5% or less △: Viscosity increase of more than 5% The evaluation results are shown in Table 2.

[0205] [Table 2] [Industrial Applicability]

[0206] The luminescent nanoparticle composite of the present invention has excellent atmospheric storage stability and heat resistance. An ink composition containing such a luminescent nanoparticle composite can provide a light conversion layer with excellent luminescent properties and a color filter for use in mobile terminals, televisions, monitors, etc., and is useful as a liquid crystal display device or a self-luminous display device. [Explanation of symbols]

[0207] 10 Pixel section 10a First pixel section 10b Second pixel section 10c Third pixel section 11a. First luminescent nanoparticle complex 11b Second luminescent nanoparticle complex 12a First light scattering particle 12b Second light scattering particle 12c Third light scattering particle 20 Light blocking section 30 Light conversion layer 40 Base material 100 color filters

Claims

1. A luminescent nanoparticle complex in which an organic ligand is coordinated to the surface of a luminescent nanoparticle, The organic ligand is a compound represented by the following formula (1) and has a molecular weight of 200 to 350. 【Chemistry 1】 [In formula (1), R １ represents an alkylene group having 1 to 6 carbon atoms, and one —CH ２ - is replaced by -OCO-, or two or more non-adjacent -CH ２ One of -CH ２ - is replaced by -OCO-, and the remaining -CH ２ - is substituted with at least one of -O-, -S-, -CO-, -OCO-, -NH-, -CONH-, or -NHCO-, and R ２ represents an alkylene group or a (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.

2. Two —CH groups that are not adjacent to each other in the alkylene group ２ One of -CH ２ - is replaced by -OCO-, and the remaining -CH ２ The luminescent nanoparticle composite of claim 1 , wherein - is substituted with -S-.

3. The luminescent nanoparticle composite according to claim 1, wherein the organic ligand represented by formula (1) is selected from the following Carboxylic Acids 1 to 10. 【Chemistry 2】

4. The luminescent nanoparticle composite according to claim 1 or 2, wherein X in the formula (1) is an aryl group.

5. The Hansen solubility parameter δD value of the organic ligand is 17.4 MPa. ０．５ The luminescent nanoparticle composite according to any one of claims 1 to 3, wherein the luminescent nanoparticle composite is a luminescent nanoparticle composite having a molecular weight of 1000 or more.

6. 6. The luminescent nanoparticle composite according to claim 1, wherein the luminescent nanoparticle is a core-shell structured luminescent nanoparticle containing indium and phosphorus in the core.

7. An ink composition comprising the luminescent nanoparticle composite according to any one of claims 1 to 6 and a photopolymerizable compound.

8. The ink composition according to claim 7 , wherein the photopolymerizable compound is a radically photopolymerizable compound.

9. The ink composition according to claim 7 or 8, wherein the photopolymerizable compound is alkali-insoluble.

10. The ink composition according to any one of claims 7 to 9, further comprising an antioxidant.

11. The ink composition according to any one of claims 7 to 10, further comprising a zinc compound having zinc as a central metal and having two ligands coordinated to the zinc.

12. The ink composition according to any one of claims 7 to 11, which is used in a droplet ejection method using an inkjet system.

13. The ink composition according to any one of claims 7 to 12, which is for use in a color filter.

14. A light conversion layer comprising a cured product of the ink composition according to any one of claims 7 to 13.

15. A light conversion layer including a plurality of pixel units, The light conversion layer has a plurality of pixel portions each including a cured product of the ink composition according to any one of claims 7 to 13.

16. Further, a light-shielding portion is provided between the plurality of pixel portions, the plurality of pixel units include a first pixel unit that includes the cured product and contains, as the luminescent nanoparticle composite, a luminescent nanoparticle composite that absorbs light having a wavelength in a range of 420 to 480 nm and emits light having an emission peak wavelength in a range of 605 to 665 nm; a second pixel unit that includes the cured product and contains, as the light-emitting nanoparticle composite, a light-emitting nanoparticle composite that absorbs light in a wavelength range of 420 to 480 nm and emits light having an emission peak wavelength in a range of 500 to 560 nm; and 16. The light conversion layer of claim 15, having

17. A color filter comprising the light conversion layer according to any one of claims 14 to 16.

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