Luminescent nanoparticle composite, ink composition, photoconversion layer, and color filter

Abstract

The present invention provides a luminescent nanoparticle composite that exhibits excellent atmospheric storage stability and heat resistance, and in particular, excellent stability in maintaining external quantum efficiency. Furthermore, it provides an ink composition containing such a luminescent nanoparticle composite, which exhibits excellent dispersibility and can prevent a decrease in luminescence properties, as well as a photoconversion layer and a color filter with excellent luminescence properties. [Solution] A luminescent nanoparticle composite in which an organic ligand is coordinated to the surface of luminescent nanoparticles, characterized in that the organic ligand is represented by the following formula (1). (In formula (1), R 1 R represents an alkylene group having 1 to 6 carbon atoms, where one -CH2- in the alkylene group is replaced with -OCO-, or where one of two or more non-adjacent -CH2- in the alkylene group is replaced with -OCO-, and the remaining -CH2- are replaced with -O-, etc. 2 (where X represents an alkylene group with 1 to 10 carbon atoms, and X represents a substituent with a cyclic structure.) JPEG2026062832000024.jpg31170

Description

[Technical Field]

[0001] The present invention relates to a luminescent nanoparticle composite, an ink composition, a photoconversion layer, and a color filter. [Background technology]

[0002] Liquid crystal displays (LCDs) are widely used in applications such as mobile devices, televisions, and monitors. The color filters used in these LCDs are manufactured by photolithography, which forms a black matrix and red, green, and blue pixel patterns. Specifically, in photolithography, a photosensitive resin composition containing colorants such as pigments and dyes is coated onto a substrate, dried, masked with UV irradiation, uncured areas are removed by alkaline development, and then fired. In recent years, self-emissive displays, which combine organic EL elements that emit white light 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 the light is absorbed by the color filter in principle, so there was a fundamental limitation in reducing power consumption by improving the transmittance of the color filter itself.

[0004] To address this challenge of reducing power consumption, a method of using quantum dots, which are luminescent nanocrystalline particles, in the light conversion layer instead of conventional color filters has recently attracted attention. This light conversion layer is formed on a substrate on which a black matrix is ​​formed, and includes a red-emitting quantum dot layer that is excited by blue light and emits red fluorescence, a green-emitting quantum dot layer that is excited by blue light and emits green fluorescence, and a blue light-transmitting layer that transmits blue light. By combining this light conversion layer with a blue-emitting LED backlight or a blue-emitting organic EL element, a liquid crystal display device or a self-emissive display device is constructed.

[0005] Display devices equipped with such a light conversion layer can achieve higher light utilization efficiency than conventional display devices equipped with color filters. Furthermore, since fluorescence with a small half-width spectrum emitted from quantum dots can be directly used for color display in the display device, it is possible to create a display device with a wide color reproduction range.

[0006] For example, a method is known in which a photoconversion layer is manufactured by forming a coating film on one side of a substrate using a photosensitive resin composition containing quantum dots, patterning it by photolithography, and then curing the resulting coating film by heat treatment (see, for example, Patent Document 1). However, photolithography involves many steps and is complicated, and since the photosensitive resin composition is removed by alkaline development, it inevitably results in the waste of raw materials.

[0007] One known method for reducing raw material waste is the inkjet method. The inkjet method allows for the simultaneous formation of red and green quantum dot layers in the photoconversion layer, thereby increasing manufacturing efficiency. Furthermore, since all of the ejected ink (photosensitive resin composition) can be used, it minimizes raw material waste, unlike the photolithography method. For example, an inkjet ink containing dispersed quantum dots has been disclosed for use in patterning the photoconversion layer used in combination with a blue-emitting organic EL element (see, for example, Patent Document 2). On the other hand, ink compositions with a higher content of luminescent nanocrystalline particles have been proposed from the viewpoint of improving the optical properties of the light conversion layer (for example, the external quantum efficiency (EQE)) (see, for example, Patent Document 3). Furthermore, it has been proposed that dispersion stability and optical properties can be improved by surface-treating luminescent nanocrystalline particles with a specific compound and having at least a portion of the surface have the compound as a ligand (see, for example, Patent Document 4). [Prior art documents] [Patent Documents]

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0009] Ink compositions containing quantum dots and their film - formed products have problems of deterioration caused by oxygen and moisture contained in the atmosphere. When an ink composition containing quantum dots is supplied to a large - area region to manufacture a coated or printed product, completely isolating them from the atmosphere requires placing most of the coating or printing apparatus in a high - purity inert gas atmosphere, resulting in huge equipment investment and the like. Also, in the heating process of manufacturing a pixel portion, it is required that the external quantum efficiency does not decrease (heat resistance). However, when using a conventional ink composition containing luminescent nanoparticles, it cannot always be said that a pixel portion with sufficient heat resistance can be obtained.

[0010] According to the study by the present inventors, regarding the method of surface - treating quantum dots, which are luminescent nanocrystal particles, with a specific compound, it has been found that there is still room for improvement in the stability of the external quantum efficiency during atmospheric storage and heating for carboxylic acid compounds. An object of the present invention is to provide a luminescent nanoparticle composite excellent in atmospheric storage stability and heat resistance, particularly excellent in the maintenance stability of the external quantum efficiency. Another object of the present invention is to provide an ink composition containing such a luminescent nanoparticle composite, having excellent dispersibility and capable of preventing a decrease in luminescence characteristics, a light - conversion layer having excellent luminescence characteristics, and a color filter.

Means for Solving the Problems

[0011] The inventors of the present invention have found that the atmospheric storage stability and heat resistance can be improved by using a carboxylic acid compound having a specific chemical structure in a luminescent nanoparticle composite, and thus 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 on the surface of a luminescent nanoparticle, wherein the organic ligand is represented by the following formula (1). [Chemical formula] [In formula (1), R 1 represents an alkylene group having 1 to 6 carbon atoms, one -CH2- in the alkylene group is substituted with -OCO-, or one of two or more non - adjacent -CH2- in the alkylene group is substituted with -OCO-, and the remaining -CH2- is substituted with at least one of -O-, -S-, -CO-, -OCO-, -NH-, -CONH- or -NHCO-, and R 2 represents an alkylene group having 1 to 10 carbon atoms or a (poly)oxyalkylene group, and X represents a substituent having a cyclic structure.]

[0013] According to the luminescent nanoparticle composite of the above aspect, an ink composition having excellent dispersibility and capable of preventing a decrease in luminescent properties, a light conversion layer having excellent luminescent properties, and a color filter can be formed.

[0014] One aspect of the present invention is that the X in formula (1) is an aryl group.

[0015] One aspect of the present invention is that the δD value of the Hansen solubility parameter of the organic ligand is 17.4 MPa 0.5 or more.

[0016] One aspect of the present invention is that the luminescent nanoparticle is a core - shell structured luminescent nanoparticle containing indium and phosphorus in the core.

[0017] One aspect of the present invention is an ink composition containing the above-described luminescent nanoparticle composite and a photopolymerizable compound.

[0018] One aspect of the present invention is that the photopolymerizable compound is a photoradical polymerizable compound.

[0019] One aspect of the present invention is that the photopolymerizable compound is alkali-insoluble.

[0020] One aspect of the present invention is that the ink composition contains an antioxidant.

[0021] One aspect of the present invention is that the ink composition has zinc as the central metal and contains a zinc compound having two ligands that coordinate to the zinc.

[0022] One aspect of the present invention is that the ink composition is used in an inkjet droplet ejection method.

[0023] One aspect of the present invention is that the ink composition is for use in color filters.

[0024] One aspect of the present invention relates to a photoconversion layer made of a cured product of the ink composition described above.

[0025] One aspect of the present invention is that the photoconversion layer is alkali-insoluble.

[0026] One aspect of the present invention is that the light conversion layer comprises a plurality of pixel portions, and each of the plurality of pixel portions comprises a pixel portion containing a cured product of the ink composition described above.

[0027] One aspect of the present invention is that the light conversion layer further comprises light-shielding portions provided between a plurality of pixel portions, and the plurality of pixel portions include a first pixel portion containing a cured product of the above-mentioned ink composition and containing a luminescent nanoparticle composite that absorbs light with wavelengths in the range of 420 to 480 nm and emits light having an emission peak wavelength in the range of 605 to 665 nm as a luminescent nanoparticle composite, and a second pixel portion containing a luminescent nanoparticle composite that absorbs light with wavelengths in the range of 420 to 480 nm and emits light having an emission peak wavelength in the range of 500 to 560 nm as a luminescent nanoparticle composite.

[0028] One aspect of the present invention is that the light conversion layer comprises a third pixel portion having a transmittance of 30% or more for light with wavelengths in the range of 420 to 480 nm.

[0029] One aspect of the present invention is that the light conversion layer is a color filter. [Effects of the Invention]

[0030] According to the present invention, it is possible to provide a luminescent nanoparticle composite that is excellent in atmospheric storage stability and heat resistance, and in particular in the stability of maintaining external quantum efficiency; an ink composition containing such a luminescent nanoparticle composite that is excellent in dispersibility and can prevent a decrease in luminescence properties; a photoconversion layer and a color filter with excellent luminescence properties. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic cross-sectional view of a color filter according to one embodiment of the present invention. [Modes for carrying out the invention]

[0032] Embodiments of the present invention will be described in detail below. In this specification, numerical ranges indicated using "~" represent a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively.

[0033] The present invention relates to a luminescent nanoparticle composite in which an organic ligand is coordinated to the surface of luminescent nanoparticles, characterized in that the organic ligand is a compound represented by the following formula (1) and having a molecular weight of 200 to 350. [ka] [In formula (1), R 1 R represents an alkylene group having 1 to 6 carbon atoms, and one or more non-adjacent -CH2- atoms in the alkylene group may be independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH-, or -NHCO-. 2 [wherein X represents an alkylene group or (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.]

[0034] The luminescent nanoparticle composite of the present invention can be used, for example, in an ink composition for forming the pixel portion of a light conversion layer in a color filter or the like. In other words, 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 the pixel portion of a color filter). Such an ink composition has excellent dispersibility of the luminescent nanoparticle composite and can prevent a decrease in optical properties. The reason why the above effects are obtained is not clear, but the inventors of this invention surmise as follows.

[0035] Due to their rigid molecular structure, organic ligands with cyclic structures exhibit restricted molecular motion compared to linear or branched organic ligands. Therefore, when organic ligands with cyclic structures are coordinated to the surface of luminescent nanoparticles, radical generation during air storage and heating is suppressed. Furthermore, when organic ligands with a molecular weight below a certain level are used, the cyclic structure is introduced at a high density near the luminescent nanoparticles, increasing the cohesive energy density and reducing gas permeability to oxygen and moisture. Consequently, radicals, oxygen, and moisture that cause oxidation of surface elements of luminescent nanoparticles are reduced. Therefore, luminescent nanoparticle composites in which organic ligands with cyclic structures and a molecular weight below a certain level are coordinated to luminescent nanoparticles exhibit suppressed degradation due to oxidation of surface elements and superior stability in maintaining external quantum efficiency during air storage and heating.

[0036] Furthermore, by using a carboxylic acid compound with a specific structure as an organic ligand, the affinity for both the luminescent nanoparticles and the photopolymerizable compound is increased, allowing them to be uniformly distributed in the ink composition. Therefore, the luminescent nanoparticle composite can be uniformly dispersed in the ink composition, and the degradation of the luminescent nanoparticles can be prevented. As a result, it is believed that the present invention provides an ink composition that exhibits excellent dispersibility of luminescent nanoparticle composites and can sufficiently prevent a decrease in optical properties. This effect of preventing a decrease in optical properties is suitably exhibited during storage of the ink composition, during the fabrication of pixel portions, and so on.

[0037] Furthermore, the ink composition containing the luminescent nanoparticle composite of the present invention yields pixel portions with excellent external quantum efficiency. Moreover, because the luminescent nanoparticles are uniformly dispersed in the ink composition of the present invention, excellent ejection stability is easily obtained in inkjet droplet ejection methods (hereinafter also referred to as "inkjet methods"). In other words, the ink composition of the present invention can be suitably used in inkjet methods.

[0038] Furthermore, according to the ink composition of the present invention, the luminescent nanoparticle composite has a specific carboxylic acid compound, which suppresses the decrease in external quantum efficiency due to heating. In other words, according to the ink composition of the present invention, it is easy to form pixel portions with excellent heat resistance (stability of external quantum efficiency).

[0039] The ink composition of one embodiment can be applied as an ink for manufacturing color filters, but it is preferable to prepare and use it appropriately to suit the inkjet method rather than the photolithography method, in that it can form pixel areas (light conversion layers) by using only the necessary amount in the necessary places without wasting relatively expensive materials such as luminescent nanoparticles and solvents. In addition to the luminescent nanoparticle composite and photopolymerizable compound, such an ink composition may further contain other components such as light scattering particles, polymer dispersants, and organic solvents, as described later, if necessary.

[0040] [Luminescent nanoparticle composite] First, the luminescent nanoparticles and organic ligands that constitute the luminescent nanoparticle composite of the present invention will be described.

[0041] [Luminescent nanoparticles] Generally, luminescent nanoparticles are nano-sized crystalline materials that absorb excitation light and emit fluorescence or phosphorescence. These luminescent nanoparticles are, for example, crystalline materials with a maximum particle size of 100 nm or less, as measured by a transmission electron microscope or scanning electron microscope.

[0042] Luminescent nanoparticles can, for example, absorb light of a predetermined wavelength and then emit light of a different wavelength (fluorescence or phosphorescence). Luminescent nanoparticles may be red-luminescent nanocrystalline particles that emit light (red light) having an emission peak in the wavelength range of 605 to 665 nm, green-luminescent nanocrystalline particles that emit light (green light) having an emission peak in the wavelength range of 500 to 560 nm, or blue-luminescent nanocrystalline particles that emit light (blue light) having an emission peak in the wavelength range of 420 to 480 nm. Furthermore, the light absorbed by the luminescent nanoparticles may be, for example, light in the range of wavelengths between 400 nm and 500 nm (particularly wavelengths between 420 and 480 nm) (blue light), or light in the range of wavelengths between 200 nm and 400 nm (ultraviolet light). The wavelength of the emission peak of luminescent nanoparticles can be determined, for example, by measuring the fluorescence spectrum or phosphorescence spectrum using a spectrofluorometer.

[0043] The red-emitting nanocrystalline particles preferably have emission peaks in the wavelength range of 665nm or less, 663nm or less, 660nm or less, 658nm or less, 655nm or less, 653nm or less, 651nm or less, 650nm or less, 647nm or less, 645nm or less, 643nm or less, 640nm or less, 637nm or less, 635nm or less, 632nm or less, or 630nm or less, and preferably have emission peaks in the wavelength range of 628nm or more, 625nm or more, 623nm or more, 620nm or more, 615nm or more, 610nm or more, 607nm or more, or 605nm or more. These upper and lower limits can be combined in any way. Similarly, in the following descriptions, the upper and lower limits listed individually can be combined in any way.

[0044] The green-emitting nanocrystalline particles preferably have emission peaks 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, 543 nm or less, 537 nm or less, 535 nm or less, 532 nm or less, or 530 nm or less, and preferably have emission peaks 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.

[0045] The blue-emitting nanocrystalline particles preferably have emission peaks 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 preferably have emission peaks 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.

[0046] The wavelength (emission color) of light emitted by luminescent nanoparticles, according to the solution to the Schrödinger wave equation in the square-well model, depends not only on the size (e.g., particle diameter) of the luminescent nanoparticles but also on the energy gap they possess. Therefore, the emission color can be selected (adjusted) by changing the constituent material and size of the luminescent nanoparticles used.

[0047] The luminescent nanoparticles may be luminescent nanoparticles containing semiconductor materials (luminescent semiconductor nanoparticles). Examples of such luminescent nanoparticles include quantum dots and quantum rods. Among these, quantum dots are preferred as luminescent nanoparticles because they allow for easy control of the emission spectrum, ensure reliability, reduce production costs, and improve mass production.

[0048] The luminescent nanoparticles constituting the luminescent nanoparticle composite of the present invention are core-shell structured luminescent nanoparticles containing indium (In) and phosphorus (P) in their cores. In other words, the structure of the luminescent nanoparticle has a core containing In and P as a first semiconductor material, and a shell covering at least a portion of this core and containing a second semiconductor material different from the first semiconductor material. Furthermore, in addition to a shell containing a second semiconductor material (first shell), the luminescent nanoparticle may also have a shell (second shell) that covers at least a portion of this 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 shell may be a mixed crystal containing two or more semiconductor materials (e.g., InP+GaP, ZnS+ZnSe, etc.). The luminescent nanoparticle composite of the present invention contains In and P as constituent elements in its core, resulting in a narrow band gap, making it suitable for 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, and the stability of the external quantum efficiency is improved.

[0049] Examples of the first semiconductor material containing In and P that constitutes the core of the luminescent nanoparticles include InP, InNP, InPAs, InPSb, GaInP, GaInNP, GaInPAs, GaInPSb, InAlNP, InAlPAs, and InAlPSb.

[0050] The second or third semiconductor material constituting the shell of the luminescent nanoparticles preferably includes at least one semiconductor material selected from the group consisting of group II-VI semiconductors, group III-V semiconductors, group I-III-VI semiconductors, group IV semiconductors, and group I-II-IV-VI semiconductors.

[0051] 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 Examples include 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.

[0052] From the viewpoint of being able to easily control the emission spectrum, ensure reliability, reduce production costs, and improve mass productivity, it is preferable that the luminescent nanoparticles include 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.

[0053] Specific examples of luminescent nanoparticles constituting the luminescent nanoparticle composite of the present invention include, for example, core / shell nanoparticles comprising an InP core and a ZnS shell, core / shell nanoparticles comprising an InP core and a mixed crystal shell of ZnS and ZnSe, core / shell / shell nanoparticles comprising an InP core, a first ZnSe shell, and a second ZnS shell, and core / shell / shell nanoparticles comprising an InP core, a first mixed crystal shell of ZnS and ZnSe, and a second ZnS shell. These can be used as red-luminescent nanocrystalline particles, green-luminescent nanocrystalline particles, and blue-luminescent nanocrystalline particles.

[0054] Furthermore, by adjusting the average particle size of the luminescent nanoparticles while maintaining 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 have as little adverse effect on the human body as possible. Therefore, it is preferable to use luminescent nanoparticles that contain as little cadmium, selenium, etc. as possible on their own, or, if using luminescent nanoparticles that contain the above elements (cadmium, selenium, etc.), to combine them with other luminescent nanoparticles in a way that minimizes the amount of these elements.

[0055] The shape of the luminescent nanoparticles is not particularly limited and may be any geometric shape or any irregular shape. For example, the shape of the luminescent nanoparticles may be spherical, ellipsoidal, pyramidal, disc-shaped, branched, network-shaped, rod-shaped, etc. However, it is preferable to use particles with less directional particle shape (for example, spherical or tetrahedral particles) as the luminescent nanoparticles, as this can further improve the uniformity and fluidity of the ink composition containing the luminescent nanoparticle composite of the present invention, as described later.

[0056] The average particle size (volume average diameter) of luminescent nanoparticles is preferably 1 nm or larger, more preferably 1.5 nm or larger, and even more preferably 2 nm or larger, from the viewpoint of easily obtaining emission at the desired wavelength, and having 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 easily obtaining emission at the 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 individual particle size from the ratio of major and minor axes of the projected two-dimensional image, and then determining the average value. The size and shape of luminescent nanoparticles are thought to depend on their chemical composition, structure, manufacturing method, and manufacturing conditions.

[0057] Luminescent nanoparticles can preferably be particles that can be dispersed in colloidal form in organic solvents, photopolymerizable compounds, etc. The organic solvents are as described below. Commercially available luminescent nanoparticles can also be used. Examples of commercially available luminescent nanoparticles include indium phosphate / zinc sulfide and D-dot from NN-Labs, and InP / ZnS from Aldrich.

[0058] [organic ligand] The organic ligand constituting the luminescent nanoparticle composite of the present invention contains one or more carboxylic acid compounds having one or more carboxyl groups (hereinafter also simply referred to as "carboxylic acid compounds"). In the luminescent nanoparticle composite of the present invention, the surface (shell portion) of the luminescent nanoparticles described above is passivated (modified) with the carboxylic acid compound. Since this carboxylic acid compound, acting as an organic ligand, has a carboxyl group (-COOH), it can coordinate to the surface of luminescent nanoparticles.

[0059] Carboxylic acid compounds are represented by the following formula (1). [ka] [In formula (1), R 1 R represents an alkylene group having 1 to 6 carbon atoms, and one or more non-adjacent -CH2- atoms in the alkylene group may be independently substituted with -O-, -S-, -CO-, -COO-, -OCO-, -NH-, -CONH-, or -NHCO-. 2 [wherein X represents an alkylene group or (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.]

[0060] R 1 Examples of alkylene groups having 1 to 6 carbon atoms represented by (including those with -CH2- substitutions) include methylene groups, ethylene groups, methylmethylene groups, methylethylene groups, trimethylene groups, tetramethylene groups, pentamethylene groups, hexamethylene groups, or groups represented by the following formulas (2-1) to (2-14). Among these, formulas (2-1), (2-2), (2-3), (2-4), (2-5), (2-6), (2-7), or (2-8) are preferred, and formula (2-1) or (2-2) are more preferred. The asterisk symbol in equations (2-1) to (2-14) represents a bond with an adjacent base. [ka] [ka]

Chem.

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[0061] Examples of substituents having a cyclic structure represented by X include aryl groups, aryloxy groups, arylthio groups, heteroaryl groups, monocyclic or polycyclic cycloalkyl groups, and monocyclic or polycyclic cycloalkyloxy groups. Preferably, the substituent represented by X is an aryl group or a monocyclic cycloalkyloxy group, and more preferably an aryl group.

[0062] From the perspective of easily obtaining cured products with excellent maintenance stability of external quantum efficiency, carboxylic acid compounds have a Hansen solubility parameter (HSP value) of δD of 17.4 MPa. 0.5 Preferably, the pressure is 17.4 to 18.2 MPa. 0.5 It is more preferable that it be within that range. Furthermore, the δP value in the Hansen solubility parameter (HSP value) of the carboxylic acid compound is 3 to 9 MPa. 0.5 Furthermore, δH is 7-13 MPa 0.5 It is preferable that it be so. Here, the Hansen solubility parameter is a parameter that divides the solubility parameter introduced by Hildebrand into three components, δD, δP, and δH, and represents them in three-dimensional space. δD represents the effect due to nonpolar interactions, δP represents the effect due to inter-dipole forces, and δH represents the effect due to hydrogen bonding forces. The values ​​of the Hansen solubility parameter for various compounds are listed, for example, in Charles M. Hansen's "Hansen Solubility Parameters: A Users Handbook." Furthermore, the values ​​of the Hansen solubility parameter for compounds not listed can be estimated using computer software (Hansen Solubility Parameters in Practice (HSPiP)).

[0063] By using a carboxylic acid compound having such Hansen solubility parameters as an organic ligand, the affinity for both the luminescent nanoparticles and the photopolymerizable compound is increased, allowing them to be uniformly distributed in the ink composition. As a result, the luminescent nanoparticle complex is uniformly dispersed in the ink composition, and the degradation of the luminescent nanoparticles can be prevented. As a result, it is believed that the present invention provides an ink composition that exhibits excellent dispersibility of luminescent nanoparticle composites and can sufficiently prevent a decrease in optical properties. This effect of preventing a decrease in optical properties is suitably exhibited during storage of the ink composition, during the fabrication of pixel portions, and so on.

[0064] The molecular weight of the carboxylic acid compound is 200 to 350, with 250 or more being more preferable. It is believed that an ink composition can be obtained that prevents thickening during storage 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 viewpoint of easily obtaining an appropriate viscosity for inkjet ink and maintaining luminescence properties. The molecular weight of carboxylic acid compounds can be determined by GC-MS, GPC, or 1 It can be determined by HNMR. The molecular weight of a carboxylic acid compound with a molecular weight distribution is 1 It is preferable to determine the molecular weight by 1H NMR, and the number-average molecular weight is preferably between 200 and 350.

[0065] Suitable carboxylic acid compounds include, specifically, the following compounds: [ka]

[0066] The luminescent nanoparticle composite of the present invention is obtained by mixing the luminescent nanoparticles and a carboxylic acid compound in an organic solvent, preferably as described later. The amount of carboxylic acid compound used as an 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 per 100 parts by mass of luminescent nanoparticles, from the viewpoint of dispersion stability and maintenance of luminescence properties of the resulting luminescent nanoparticle complex. Alternatively, the amount of 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 per 100 parts by mass of luminescent nanoparticles. From these perspectives, the amount of carboxylic acid compound used may be, for example, 10 to 50 parts by mass or 20 to 40 parts by mass per 100 parts by mass of luminescent nanoparticles.

[0067] Furthermore, carboxylic acid compounds whose Hansen solubility parameter δD deviates from the above range, or other organic ligands, may be used in combination, provided that they do not inhibit the effects of the present invention. 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, octanthiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), phenylphosphonic acid, and octylphosphinic acid (OPA).

[0068] The following describes the composition of the ink composition of the present invention, which contains the luminescent nanoparticle composite and the photopolymerizable compound of the present invention. However, the present invention is not limited to these compositions, and any other compositions may be added or replaced with any compositions that exhibit similar functions. In this specification, "cured ink composition" refers to a cured product obtained by curing the curable component in the ink composition (or, if the ink composition contains a solvent component, the dried ink composition). Note that the dried cured ink composition does not necessarily need to contain a solvent component.

[0069] [Photopolymerizable compound] Photopolymerizable compounds are compounds that polymerize upon irradiation with light, and are, for example, photoradical polymerizable compounds or photocationic polymerizable compounds. Photopolymerizable compounds may be either photopolymerizable monomers or photopolymerizable oligomers (hereinafter, these will also be collectively referred to as "photopolymerizable monomers"). These photopolymerizable compounds are preferably used with a photopolymerization initiator. Photoradical polymerizable compounds are used with a photoradical polymerization initiator, and photocationic polymerizable compounds are used with a photocationic polymerization initiator. In other words, a photopolymerizable compound may contain both a photopolymerizable compound and a photopolymerization initiator. Furthermore, the photopolymerizable compound may be a combination of a photoradical polymerizable compound and a photocationic polymerizable compound, or a compound possessing both photoradical polymerizability and photocationic polymerizability may be used. In addition, the photopolymerization initiator may be a combination of a photoradical polymerization initiator and a photocationic polymerization initiator.

[0070] Examples of photoradical polymerizable compounds include monomers having an ethylenically unsaturated group (hereinafter also referred to as "ethylenically unsaturated monomers") and monomers having an isocyanate group. Here, ethylenically unsaturated monomers refer to monomers that have an ethylenically unsaturated bond (carbon-carbon double bond). Examples of ethylenically unsaturated monomers include monomers that have an ethylenically unsaturated group, such as a vinyl group, a vinylene group, and a vinylidene group. Monomers with these groups are sometimes referred to as "vinyl monomers."

[0071] The number of ethylenically unsaturated bonds (e.g., the number of ethylenically unsaturated groups) in an ethylenically unsaturated monomer is preferably 1 to 3. The ethylenically unsaturated monomer may be used alone or in combination of two or more types. 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 monomers having one or two ethylenically unsaturated groups and monomers having two or three ethylenically unsaturated groups. That is, the ethylenically unsaturated monomer can 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.

[0072] Examples of ethylenically unsaturated groups include vinyl groups, vinylene groups, 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 an ethylenically unsaturated group, and (meth)acrylates and (meth)acrylamides are more preferred.

[0073] 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, 2-hydroxyethyl acrylate, etc.

[0074] Examples of (meth)acrylamides include (meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, diacetone(meth)acrylamide, 4-acryloylmorpholine, Nt-butyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, Nt-octyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-phenyl(meth)acrylamide, N-dodecyl(meth)acrylamide, etc. 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.

[0075] Examples of monomers having two ethylenically unsaturated groups (difunctional monomers) 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, and 1 Glycol (meth)acrylates such as 9-nonanediol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, ethoxylated (2) neopentyl glycol di(meth)acrylate [compound obtained by diacrylate of a 2-mol adduct of neopentyl glycol ethylene oxide], and propoxylated (2) neopentyl glycol di(meth)acrylate [compound obtained by diacrylate of a 2-mol adduct of neopentyl glycol propylene oxide];

[0076] 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, bis(4-acryloxypolyethoxyphenyl)propane; Neopentyl glycol hydroxypivalate diacrylate, di(meth)acrylate in which two hydroxyl groups of tris(2-hydroxyethyl) isocyanurate are substituted with (meth)acryloyloxy groups, di(meth)acrylate in which two hydroxyl groups of a diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol are substituted with (meth)acryloyloxy groups. Modified bisphenol A di(meth)acrylate, bisphenol A propylene oxide (PO) adduct di(meth)acrylate, bisphenol A ethylene oxide (EO) adduct di(meth)acrylate

[0077] Di(meth)acrylates such as di(meth)acrylates obtained by adding 3 or more moles of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane, in which two hydroxyl groups of a triol are substituted with (meth)acryloyloxy groups; and di(meth)acrylates obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A, in which two hydroxyl groups of a diol are substituted with (meth)acryloyloxy groups. Examples include bis(meth)acrylamides such as N,N'-methylenebis(meth)acrylamide and N,N'-ethylenebis(meth)acrylamide; methyl 2-(allyloxymethyl)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 2-(allyloxymethyl)methyl acrylate are preferably used.

[0078] 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.

[0079] Examples of photocationically polymerizable compounds include epoxy compounds, oxetane compounds, and vinyl ether compounds.

[0080] 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, as well as alicyclic epoxy compounds such as 1,2-epoxy-4-vinylcyclohexane and 1-methyl-4-(2-methyloxyranyl)-7-oxabicyclo[4.1.0]heptane. Commercially available epoxy compounds can also be used, such as "Celoxide 2000," "Celoxide 3000," and "Celoxide 4000" manufactured by Daicel Chemical Industries, Ltd.

[0081] Cationic polymerizable oxetane compounds include 2-ethylhexyloxetane, 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3-n-butyloxetane, 3-hydroxymethyl-3-phenyloxetane, 3-hydroxymethyl-3-benzyloxetane, 3-hydroxyethyl-3-methyloxetane, 3-hydroxyethyl-3-ethyloxetane, 3-hydroxyethyl-3-propyloxetane, 3-hydroxyethyl-3-phenyloxetane, 3-hydroxypropyl-3-methyloxetane, 3-hydroxypropyl-3-ethyloxetane, 3-hydroxypropyl-3-propyloxetane, 3-hydroxypropyl-3-phenyloxetane, and 3-hydroxybutyl-3-methyloxetane.

[0082] It is also possible to use commercially available oxetane compounds. Examples of commercially available oxetane compounds include the Aron Oxetane series from Toagosei Co., Ltd. ("OXT-101", "OXT-212", "OXT-121", "OXT-221", etc.); and "Celoxide 2021", "Celoxide 2021A", "Celoxide 2021P", "Celoxide 2080", "Celoxide 2081", "Celoxide 2083", "Celoxide 2085", etc. from Daicel Chemical Industries, Ltd. "Polyd GT300", "Epolid GT301", "Epolid GT302", "Epolid GT400", "Epolid GT401", and "Epolid GT403"; "Cyracure UVR-6105", "Cyracure UVR-6107", "Cyracure UVR-6110", "Cyracure UVR-6128", "ERL4289", and "ERL4299" manufactured by Dow Chemical Japan Ltd. can be used. In addition, known oxetane compounds (for example, oxetane compounds described in Japanese Patent Application Publication No. 2009-40830, etc.) can also be used.

[0083] Examples of vinyl ether compounds include 2-hydroxyethyl vinyl ether, triethylene glycol vinyl monoether, tetraethylene glycol divinyl ether, and trimethylolpropane trivinyl ether. Furthermore, as photopolymerizable compounds, 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, or photopolymerizable compounds described in paragraphs 0042 to 0049 of Japanese Patent Application Publication No. 2013-182215 can also be used.

[0084] From the viewpoint of easily obtaining highly reliable pixel portions (cured products of the ink composition), the photopolymerizable compound is preferably alkali-insoluble. 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 photopolymerizable compound dissolved is preferably 10% by mass or less, and more preferably 3% by mass or less.

[0085] The amount of 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, per 100 parts by mass of the total of components other than organic solvents, from the viewpoint of improving the dispersion stability of the luminescent nanoparticle composite, making it easier to obtain an appropriate viscosity as an inkjet ink, from the viewpoint of improving the curability of the ink composition, from the viewpoint of making it easier to produce pixel portions with excellent shape stability, and from the viewpoint of improving the solvent resistance and abrasion resistance of the pixel portions (cured products 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, based on 100 parts by mass of the total components other than the organic solvent, from the viewpoint of easily obtaining an appropriate viscosity for inkjet ink and obtaining better luminescence characteristics (e.g., external quantum efficiency).

[0086] [Photopolymerization initiator] Photopolymerization initiators include, for example, photoradical polymerization initiators or photocationic polymerization initiators. As photoradical polymerization initiators, molecular cleavage type or hydrogen abstraction type photoradical polymerization initiators are preferred.

[0087] Suitable molecular cleavage-type photoradical polymerization initiators include, for example, benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide. Other molecular cleavage-type photoradical polymerization initiators that may be used in combination include 1-hydroxycyclohexylphenyl ketone, benzoin ethyl ether, benzyldimethyl 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.

[0088] Examples of hydrogen abstraction type photoradical polymerization initiators include benzophenone, 4-phenylbenzophenone, isophthalphenone, and 4-benzoyl-4'-methyl-diphenyl sulfide. Furthermore, a combination of a molecular cleavage-type photoradical polymerization initiator and a hydrogen abstraction-type photoradical polymerization initiator may be used as the photopolymerization initiator.

[0089] Commercially available photopolymerization initiators can also be used, such as sulfonium salt-based photocationic polymerization initiators like "CPI-100P" from Sunapro, acylphosphine oxide compounds like "Lucirin TPO" from BASF, and "Irgacure 907," "Irgacure 819," "Irgacure 379EG," "Irgacure 184," and "Irgacure PAG290" from BASF.

[0090] 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, per 100 parts by mass of the photopolymerizable compound. From the viewpoint of the long-term stability 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, per 100 parts by mass of the photopolymerizable compound.

[0091] In this ink composition, the photopolymerization initiator may be used in combination with a polymerization accelerator. Examples of polymerization accelerators include amines that do not react with photopolymerizable compounds, such as trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, and 4,4'-bis(diethylamino)benzophenone. When a polymerization accelerator is used, its content is preferably in the range of 1 to 100% by mass relative to the total amount of the photopolymerization initiator and polymerization accelerator.

[0092] [Antioxidant] The ink composition may further contain an antioxidant. The antioxidant is a compound that provides excellent external quantum efficiency maintenance performance to the pixel portion. The antioxidant is not particularly limited and examples include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among these, phenolic antioxidants or phosphorus antioxidants are preferred. These antioxidants may be used individually or in combination of two or more.

[0093] 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 ,6-Hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 1,6-Hexamethylenebis[(3,5-di-t-butyl-4-hydroxyphenyl)propionamide], 4,4'-Thiobis(6-t-butyl-m-cresol), 2,2'-Methylenebis(4-methyl-6-t-butylphenol), 2,2'-Methylenebis(4-ethyl-6-t-butylphenol), Bis[3,3-bis(4-hydroxy-3-t-butylphenyl)butyric acid]glycol ester, 4,4'-Butylidenebi Tris(6-t-butyl-m-cresol), 2,2'-ethylidenebis(4,6-di-t-butylphenol), 2,2'-ethylidenebis(4-second-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 and triethylene glycol bis[(3-t-butyl-4-hydroxy-5-methylphenyl)propionate]. Among the phenolic antioxidants, pentaerythritol tetrakis[3-[3,5-di(t-butyl)-4-hydroxyphenyl]propionate] is preferred due to its excellent solubility in ink compositions.

[0094] As a phosphorus-based antioxidant, phosphite triester compounds are preferred. Phosphite triester compounds include, for example, those with the formula: P(OR 51 )(OR 52 )(OR 53 It is a compound represented by the formula ). In the formula, R 51 , R 52 , R 53 Each of these independently represents a monovalent organic group. Also, R 51 , R 52 , R 53 Two of these may be bonded together to form a ring structure. From the viewpoint of sufficiently satisfying performance requirements such as affinity with other components in the ink composition, such as photopolymerizable compounds, and maintaining excellent external quantum efficiency of the pixel portion, the monovalent organic group is preferably a monovalent hydrocarbon group. Examples of monovalent hydrocarbon groups include alkyl groups, aryl groups, and alkenyl groups. The number of carbon atoms in the monovalent hydrocarbon group is preferably 1 to 30, and more preferably 4 to 18 from the viewpoint of solubility in the ink composition.

[0095] Alkyl groups may be linear or branched. Examples of alkyl groups include 2-ethylhexyl, butyl, octyl, nonyl, decyl, isodecyl, dodecyl, hexadecyl, and octadecyl groups. Examples of aryl groups include phenyl group, naphthyl group, t-butylphenyl group, di-t-butylphenyl group, octylphenyl group, nonylphenyl group, isodecylphenyl group, isodecylphenyl group, and isodecylnaphthyl group. The monovalent hydrocarbon group is preferably an alkyl group or an aryl group, and more preferably an alkyl group or a phenyl group, from the viewpoint of maintaining excellent external quantum efficiency of the pixel portion.

[0096] R 51 , R 52 , R 53 It is preferable that at least two of them 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 are phenyl groups. R 51 , R 52 , R 53 Preferably, at least one of these groups is a phenyl group and one is an alkyl group (particularly a branched alkyl group). In other words, 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-mentioned functional group, it can sufficiently satisfy performance requirements such as affinity with other components in the ink composition, such as photopolymerizable compounds, and suppress a decrease in the external quantum efficiency of the pixel portion.

[0097] Examples of compounds represented by the above formula include triphenyl phosphite, 2-ethylhexyldiphenyl phosphite, and diphenyloctyl phosphite. The phosphite triester compound may be liquid or solid at room temperature (25°C), but it is preferable that it be liquid at room temperature (25°C) from the viewpoint of sufficiently satisfying performance requirements such as affinity with other components in the ink composition, such as photopolymerizable compounds, and suppressing a decrease in the external quantum efficiency of the pixel area. The melting point of the phosphite triester compound is preferably 20°C or lower, and more preferably 10°C or lower.

[0098] 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, per 100 parts by mass of the photopolymerizable compound. Even adding only a small amount of antioxidant can effectively suppress the decrease in the external quantum efficiency of the pixel area. For this reason, the antioxidant content 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, per 100 parts by mass of the photopolymerizable compound.

[0099] [Light scattering particles] The ink composition may further contain light-scattering particles. These light-scattering particles are, for example, optically inert inorganic particles. When the ink composition contains light-scattering particles, it can scatter light from a light source irradiated onto the pixel area, thereby obtaining excellent optical properties (e.g., external quantum efficiency).

[0100] Examples of materials that constitute light-scattering particles include elemental metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, platinum, and gold; oxides such as silicon dioxide, talc, clay, kaolin, alumina white, titanium dioxide, 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.

[0101] From the viewpoint of excellent ejection stability of the ink composition (inkjet ink) and superior effect on improving external quantum efficiency, the light-scattering particles preferably include at least one selected from the group consisting of titanium dioxide, aluminum oxide, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate, barium titanate, and silicon oxide, and more preferably include at least one selected from the group consisting of titanium dioxide, zirconium oxide, zinc oxide, and barium titanate.

[0102] Examples of light-scattering particle shapes include spherical, filamentous, and irregular shapes. However, it is preferable that the light-scattering particles have a shape with little directionality (for example, spherical or tetrahedral). By using light-scattering particles of such shape, the uniformity, fluidity, and light scattering properties of the ink composition can be further improved, and excellent ejection stability can be ensured.

[0103] The average particle diameter (volume average diameter) of the light-scattering particles is preferably 0.05 μm or larger, more preferably 0.2 μm or larger, and even more preferably 0.3 μm or larger, from the viewpoint of excellent ejection stability of the ink composition and superior effect on improving external quantum efficiency. From the viewpoint of excellent ejection stability of the ink composition, the average particle size of the light-scattering particles is preferably 1 μm or less, more preferably 0.6 μm or less, and even more preferably 0.4 μm or less.

[0104] The average particle size of the light-scattering particles is preferably 0.05-1 μm, 0.05-0.6 μm, 0.05-0.4 μm, 0.2-1 μm, 0.2-0.6 μm, 0.2-0.4 μm, 0.3-1 μm, 0.3-0.6 μm, or 0.3-0.4 μm. In this specification, the average particle diameter of light-scattering particles is obtained by measuring it using a dynamic light-scattering nanotrack particle size analyzer and calculating the volume-averaged diameter. Furthermore, the average particle diameter of the light-scattering particles used can be obtained, for example, by measuring the particle diameter of each particle using a transmission electron microscope or scanning electron microscope and calculating the volume-average diameter.

[0105] From the viewpoint of achieving superior improvement in the external quantum efficiency of the pixel portion, the content of 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, based on 100 parts by mass of the total components other than the organic solvent contained in the ink composition. From the viewpoint of excellent ejection stability of the ink composition and superior effect on improving the external quantum efficiency of the pixel portion, the content of 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, based on 100 parts by mass of the total of components other than organic solvents contained in the ink composition.

[0106] The mass ratio of light-scattering particles to the content of luminescent nanoparticle composites (light-scattering particles / luminescent nanoparticle composites) is preferably 0.1 or higher, more preferably 0.2 or higher, and even more preferably 0.5 or higher, from the viewpoint of having an excellent effect on improving the external quantum efficiency of the pixel portion. 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 viewpoint of being superior in improving the external quantum efficiency of the pixel area and providing excellent continuous ejection (ejection stability) in the inkjet method.

[0107] From the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink, the total amount of luminescent nanoparticle composites and 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, based on 100 parts by mass of the total amount of components other than organic solvents contained in the ink composition. From the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink, the total amount of luminescent nanoparticle composites and 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, based on 100 parts by mass of the total amount of components other than organic solvents contained in the ink composition.

[0108] [Polymer dispersant] The ink composition may further contain a polymeric dispersant. The polymeric dispersant is preferably a polymer compound having a weight-average molecular weight of 750 or more and having a functional group that has affinity for light-scattering particles. Polymeric dispersants have the function of stably dispersing light-scattering particles in an ink composition. These polymeric dispersants adsorb onto light-scattering particles via functional groups that have an affinity for light-scattering particles, and disperse the light-scattering particles in the ink composition through electrostatic and / or steric repulsion between polymeric dispersants.

[0109] When the ink composition contains a polymeric dispersant, the light-scattering particles can be dispersed well even when the content of light-scattering particles is relatively high (for example, about 60% by mass). The polymeric dispersant is preferably bound to the surface of the light-scattering particles. However, the polymeric dispersant may also be bound to the surface of the luminescent nanoparticle composite, or it may be free in the ink composition. Examples of functional groups that have affinity for light-scattering particles include acidic functional groups, basic functional groups, and nonionic functional groups. Acidic functional groups have dissociable protons and may be neutralized by bases such as amines and hydroxide ions, while basic functional groups may be neutralized by acids such as organic acids and inorganic acids.

[0110] Examples of acidic functional groups include carboxyl groups (-COOH), sulfo groups (-SO3H), sulfate groups (-OSO3H), phosphonic acid groups (-PO(OH)3), phosphate groups (-OPO(OH)3), phosphinic acid groups (-PO(OH)-), and mercapto groups (-SH). 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 hydroxyl groups, ether groups, thioether groups, sulfinyl groups (-SO-), sulfonyl groups (-SO2-), carbonyl groups, formyl groups, ester groups, carbonate ester groups, amide groups, carbamoyl groups, ureido groups, thioamide groups, thioureido groups, sulfamoyl groups, cyano groups, alkenyl groups, alkynyl groups, phosphine oxide groups, and phosphine sulfide groups.

[0111] The polymeric dispersant may be a polymer (homopolymer) of a single monomer, or a copolymer (copolymer) of multiple monomers. Furthermore, the polymeric dispersant may be a random copolymer, a block copolymer, or a graft copolymer. If 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, polyethyleneimines, polyamines such as polyallylamines, and polyimides.

[0112] Commercial polymer dispersants can also be used. Examples of commercially available polymer dispersants include the Azisper PB series from Ajinomoto Fine Techno Co., Ltd., the Disper BYK series from BYK, and the Efka series from BASF.

[0113] [Zinc compounds] The ink composition may further contain a zinc compound having zinc as the central metal and two ligands coordinating to the zinc. Preferably, the zinc compound has one zinc atom and the zinc is divalent. When such a zinc compound is further included, the wavelength shift of the converted light in the pixel area (a phenomenon in which the wavelength of the converted light emitted from the pixel area shifts to a longer wavelength than the emission wavelength of the luminescent nanoparticle composite) can be reduced.

[0114] In this zinc compound, each of the two ligands has a sulfur atom, and these sulfur atoms are directly bonded to the zinc (e.g., by an ionic bond), thereby coordinating with the zinc. The two ligands may be identical 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 wavelength shift reduction effect tends to be more pronounced, and the initial external quantum efficiency and photostability of the pixel area tend to be superior. The molecular weight of the zinc compound may be 600 or less, or 500 or less. Furthermore, the molecular weight of the zinc compound may be 200 or more from the viewpoint of easily improving solubility in the ink composition and easily obtaining the wavelength shift reduction effect.

[0115] The above ligand is preferably a compound having a coordinating functional group containing a sulfur atom. In such a ligand, the sulfur atom of the coordinating functional group is directly bonded to zinc, thereby coordinating to zinc. Examples of coordinating functional groups include thiol groups (mercapto groups), dithiocarbamate groups, dithiocarboxylic acid groups, and thiocarboxylic acid groups. These coordinating functional groups, for example, are deprotonated and bonded to zinc. That is, the ligands may be coordinated to zinc in an ionized state.

[0116] Examples of compounds having the above-mentioned coordinating functional group include dithiocarbamates such as monoalkyldithiocarbamate, dialkyldithiocarbamate, diaryldithiocarbamate, alkylaryldithiocarbamate, and dialkyldithiocarbamate; mercaptopyridines such as 2-mercaptopyridine N-oxide; mercaptobenzothiazoles such as 2-mercaptobenzothiazole; and mercaptobenzoxazoles such as 2-mercaptobenzoxazole. From the viewpoint of further improving external quantum efficiency, further improving photostability, and obtaining a more pronounced effect of reducing wavelength shift, it is preferable that at least one of the two ligands is a dithiocarbamate (a compound having a dithiocarbamate group as a coordinating functional group), and it is more preferable that both ligands are dithiocarbamates (compounds having a dithiocarbamate group as a coordinating functional group).

[0117] Specific examples of zinc compounds include zinc bis(2-hydroxyethyl)dithiocarbamate, zinc bis(2-mercaptopyridine N-oxide), zinc (toluene-3,4-dithiolat), zinc bis(dibenzyldithiocarbamate), zinc bis(dibutyldithiocarbamate), zinc bis(diethyldithiocarbamate), zinc bis(N-ethyl-N-phenyldithiocarbamate), and zinc bis(2-mercaptobenzothiazole). These can also be commercially available products, such as "Noxellar BZ" manufactured by Ouchi Shinko Chemical Industry Co., Ltd., and "Zinc Pyrithione" manufactured by Tokyo Chemical Industry Co., Ltd.

[0118] From the viewpoint of further improving external quantum efficiency, further improving photostability, and obtaining a more significant effect of reducing wavelength shift, the zinc compound content 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, based on 100 parts by mass of the total of components other than organic solvents contained in the ink composition. Furthermore, from a similar viewpoint, the zinc compound content 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, based on 100 parts by mass of the total components other than the organic solvent contained in the ink composition.

[0119] [Organic solvents] The ink composition may also contain organic solvents as needed. 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.

[0120] From the viewpoint of the continuous ejection stability of the ink composition (inkjet ink), the boiling point of the organic solvent is preferably 150°C or higher, and more preferably 180°C or higher. Furthermore, when forming the pixel portion, it is necessary to remove the organic solvent from the ink composition before the ink composition hardens. Therefore, from the viewpoint of facilitating the removal of the organic solvent, it is preferable that the boiling point of the organic solvent be 300°C or lower.

[0121] The organic solvent preferably contains an acetate compound with a boiling point of 150°C or higher. In this case, the affinity between the luminescent nanoparticle composite and the organic solvent is further improved, and the luminescent nanoparticle composite can exhibit excellent 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.

[0122] In the ink composition of this embodiment, since the photopolymerizable compound also functions as a dispersion medium, it is possible to disperse the light-scattering particles and luminescent nanoparticle composite without solvents. In this case, there is the advantage that the step of removing organic solvents by drying when forming the pixel portion is unnecessary.

[0123] The ink composition may further contain additives other than those described above, such as ultraviolet absorbers, surface tension modifiers, fade inhibitors, and conductive salts, to the extent that they do not impair the effects of the present invention.

[0124] The viscosity of the ink composition at the time of ejection may be 2 mPa·s or more, 5 mPa·s or more, or 7 mPa·s or more, for example, from the viewpoint of ejection stability. The viscosity at the time of ejection may also be 20 mPa·s or less, 15 mPa·s or less, or 12 mPa·s or less. The viscosity of the ink composition at the time of dispensing is preferably 2-20 mPa·s, 2-15 mPa·s, 2-12 mPa·s, 5-20 mPa·s, 5-15 mPa·s, 5-12 mPa·s, 7-20 mPa·s, 7-15 mPa·s, or 7-12 mPa·s. In this specification, the viscosity of the ink composition at the time of ejection is the value measured using an E-type viscometer at the same temperature as at the time of ejection.

[0125] When the viscosity of the ink composition at the time of ejection is 2 mPa·s or higher, the meniscus shape of the ink composition at the tip of the ink ejection hole of the ejection head becomes 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 at the time of ejection is 20 mPa·s or less, the ink composition can be smoothly ejected from the ink ejection hole.

[0126] The surface tension of the ink composition is preferably suitable for inkjet ink, specifically 20 to 40 mN / m, and more preferably 25 to 35 mN / m. By adjusting the surface tension within this range, it becomes easier to control the ejection of the ink composition (e.g., control of the ejection amount and ejection timing), and the occurrence of flight deviations can be suppressed. Flight deviation refers to a situation where, when the ink composition is ejected from the ink ejection hole, the point of impact of the ink composition deviates by 30 μm or more from the target position.

[0127] When the surface tension is 40 mN / m or less, the meniscus shape of the ink composition at the tip of the ink ejection hole is stable, making it easier to control the ejection of the ink composition (for example, controlling the ejection amount and timing). On the other hand, if the surface tension is 20 mN / m or higher, contamination of the area around the ink ejection hole with the ink composition can be prevented, thereby suppressing the occurrence of flight deviations. In other words, it is possible to prevent the ink from not landing accurately in the formation area of ​​the pixel where it should land, resulting in pixel areas with insufficient filling of the ink composition, or to prevent the ink composition from landing in the formation area (or pixel area) adjacent to the formation area of ​​the pixel where it should land, thus preventing a decrease in color reproducibility. In this specification, the surface tension of the ink composition is the value measured at 23°C using the ring method (also known as the ring-to-ring method).

[0128] When using the ink composition of this embodiment as an inkjet ink, it is preferable to apply it to a piezo-type inkjet recording device. In a piezo-type device, the ink composition is not exposed to high temperatures instantaneously 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 embodiment can also be used in methods other than inkjet printing, such as photolithography. In this case, it is preferable that the ink composition contains an alkali-soluble resin as a binder polymer.

[0129] When using an ink composition in photolithography, the ink composition is first applied to a substrate, and then the ink composition is dried to form a coating film. The resulting coating film is soluble in alkaline developer and is patterned by treatment with alkaline developer. In this case, an aqueous solution is preferably used as the alkaline developer from the viewpoint of ease of waste disposal, so the coating film of the ink composition is treated with an aqueous solution. On the other hand, in the case of ink compositions using luminescent nanoparticle composites (such as quantum dots), the luminescent nanoparticle composites are unstable in water, and their luminescence properties (e.g., fluorescence properties) may be impaired by moisture. The ink composition of the present invention is preferably used in inkjet methods, which do not require treatment with an alkaline developer (aqueous solution).

[0130] 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 easily absorb moisture from the atmosphere, which may cause the luminescence properties (e.g., fluorescence properties) of the luminescent nanoparticle composite (quantum dots, etc.) to deteriorate over time. From the viewpoint of more reliably reducing the occurrence of problems due to water absorption, in this embodiment, it is preferable that the coating film of the ink composition is alkali-insoluble. That is, the ink composition of this embodiment is preferably an ink composition capable of forming an alkali-insoluble coating film.

[0131] Such ink compositions can be obtained by using an alkali-insoluble photopolymerizable compound as the photopolymerizable compound. Here, the alkali-insoluble nature of the coating film of the ink composition 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 above dissolution amount is preferably 10% by mass or less, and more preferably 3% by mass or less. Furthermore, the fact that the ink composition is capable of forming an alkali-insoluble coating film can be confirmed by measuring the amount of solubility 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.

[0132] <Method for manufacturing ink composition> The ink composition of this embodiment comprises, for example, a step of mixing the above-mentioned components (luminescent nanoparticle composite, photopolymerizable compound, and other optional components). The method for producing the ink composition may further include a step of dispersing the mixture of the above-mentioned components. The following describes, as an example, a method for producing an ink composition containing light-scattering particles.

[0133] A method for producing an ink composition containing light-scattering particles comprises, 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 composite of luminescent nanoparticles. The dispersion of light-scattering particles may further contain a polymeric dispersant. In this method, the dispersion of light-scattering particles may further contain a photopolymerizable compound, and the photopolymerizable compound may be further mixed in the second step. According to the above method, light-scattering particles can be sufficiently dispersed. Therefore, it is possible to improve the optical properties of the pixel area (e.g., external quantum efficiency) and easily obtain an ink composition with excellent ejection stability.

[0134] In the first step, a dispersion of light-scattering particles may be prepared by mixing light-scattering particles with, if necessary, a polymeric dispersant and a photopolymerizable compound, and then performing a dispersion treatment. Mixing and dispersion can be carried out using, for example, a bead mill, paint conditioner, planetary agitator, jet mill, or other dispersion device. From the viewpoint of achieving good dispersibility of light-scattering particles and making it easy to adjust the average particle size of the light-scattering particles to a desired range, it is preferable to use a bead mill or paint conditioner. Furthermore, by mixing the light-scattering particles with a polymer dispersant before mixing the luminescent nanoparticle composite with the light-scattering particles, the light-scattering particles can be dispersed more effectively. Therefore, excellent discharge stability and superior external quantum efficiency can be obtained more easily.

[0135] The method for producing the ink composition may further include a step before the second step of preparing a dispersion of luminescent nanoparticles containing the luminescent nanoparticle complex and a photopolymerizable compound. In this case, the second step involves mixing a dispersion of light-scattering particles with the dispersion of luminescent nanoparticles. In the step of preparing a dispersion of luminescent nanoparticle composites, the dispersion of luminescent nanoparticle composites may be prepared by mixing the luminescent nanoparticle composites with a photopolymerizable compound and performing a dispersion treatment.

[0136] Mixing and dispersion can be carried out using, for example, a bead mill, paint conditioner, planetary agitator, jet mill, or other dispersion device. From the viewpoint of achieving good dispersibility of the luminescent nanoparticle composite and easily adjusting the average particle size of the luminescent nanoparticle composite to a desired range, it is preferable to use a bead mill, paint conditioner, or jet mill. This method allows for sufficient dispersion of the luminescent nanoparticle composite. As a result, it is possible to improve the optical properties of the pixel area (e.g., external quantum efficiency) and easily obtain an ink composition with excellent ejection stability.

[0137] In the above manufacturing method, when other components such as antioxidants and organic solvents are added, these components may be mixed into a dispersion of luminescent nanoparticle composites, into a dispersion of light-scattering particles, or into a mixed dispersion obtained by mixing a dispersion of luminescent nanoparticle composites and a dispersion of light-scattering particles.

[0138] <Ink Composition Set> An ink composition set according to one embodiment comprises the ink composition of the embodiment described above. In addition to the ink composition of the embodiment described above (luminescent ink composition), the ink composition set may also include an ink composition that does not contain luminescent nanoparticle composites (non-luminescent ink composition). The non-luminescent ink composition is, for example, a conventionally known ink composition. The non-luminescent ink composition can have the same composition as the ink composition (luminescent ink composition) of the above-described embodiment, except that it does not contain a luminescent nanoparticle composite.

[0139] The non-luminescent ink composition does not contain luminescent nanoparticle composites. Therefore, when light is incident on a pixel portion formed with the non-luminescent ink composition (a pixel portion containing a cured product of the non-luminescent ink composition), the light emitted from the pixel portion has approximately the same wavelength as the incident light. Therefore, non-emissive ink compositions are suitably used to form pixel portions of the same color as the light from the light source. For example, if the light from the light source is in the wavelength range of 420 to 480 nm (blue light), the pixel portions formed by the non-emissive ink composition may become blue pixels.

[0140] The non-luminescent ink composition preferably contains light-scattering particles. When the non-luminescent ink composition contains light-scattering particles, the pixel portion formed by the non-luminescent ink composition can scatter incident light. This makes it possible to reduce the difference in light intensity at the viewing angle of the light emitted from the pixel portion.

[0141] <Photoconversion layer and color filter> Next, the details of the light conversion layer and color filter obtained using the ink composition set of the above-described embodiment will be explained with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant explanations will be omitted. Figure 1 is a schematic cross-sectional view of a color filter according to one embodiment of the present invention. For the sake of explanation, the upper side of Figure 1 will be referred to as "top" or "upper," and the lower side will be referred to as "bottom" or "downward." The color filter 100 shown in Figure 1 comprises a substrate 40 and a light conversion layer 30 provided on the substrate 40. The light conversion layer 30 includes a plurality of pixel sections 10 and a light-shielding section 20.

[0142] The light conversion layer 30 has a pixel section 10 which includes a first pixel section 10a, a second pixel section 10b, and a third pixel section 10c. The first pixel section 10a, the second pixel section 10b, and the third pixel section 10c are arranged in a grid pattern so as to repeat in this order. The light-shielding portion 20 is provided between adjacent pixel portions 10, that is, between the first pixel portion 10a and the second pixel portion 10b, between the second pixel portion 10b and the third pixel portion 10c, and between the third pixel portion 10c and the first pixel portion 10a. In other words, adjacent pixel portions 10 are separated by the light-shielding portion 20.

[0143] The first pixel portion 10a and the second pixel portion 10b are luminescent pixel portions (luminescent pixel portions) containing a luminescent nanoparticle composite, a curing component, and light-scattering particles. At least one of the first pixel portion 10a or the second pixel portion 10b contains a cured product of the ink composition described above. As shown in Figure 1, the first pixel portion 10a includes a first curing component 13a and a first luminescent nanoparticle composite 11a and first light-scattering particles 12a dispersed in the first curing component 13a. Similarly, the second pixel portion 10b includes a second curing component 13b and a second luminescent nanoparticle composite 11b and second light-scattering particles 12b dispersed in the second curing component 13b.

[0144] The curing 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 polymeric dispersants and unreacted photopolymerizable compounds). In the first pixel portion 10a and the second pixel portion 10b, the first curing component 13a and the second curing component 13b may be the same or different. Also, the first light-scattering particle 12a and the second light-scattering particle 12b may be the same or different.

[0145] The first luminescent nanoparticle composite 11a is a red luminescent nanoparticle composite that absorbs light in the wavelength range of 420-480 nm and emits light having an emission peak in the wavelength range of 605-665 nm. In other words, the first pixel portion 10a can be called a red pixel portion for converting blue light into red light. Furthermore, the second luminescent nanoparticle composite 11b is a green luminescent nanoparticle composite that absorbs light in the wavelength range of 420-480 nm and emits light having an emission peak in the wavelength range of 500-560 nm. In other words, the second pixel portion 10b can be called a green pixel portion for converting blue light into green light.

[0146] 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 being superior in terms of improving external quantum efficiency and obtaining excellent luminescence intensity. From the viewpoint of excellent reliability of the pixel portion and obtaining excellent luminescence intensity, the content of the luminescent nanoparticle composite is preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and particularly preferably 60% by mass or less, based on the total mass of the cured product of the luminescent ink composition.

[0147] From the viewpoint of achieving superior improvement in external quantum efficiency, the content of 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 superior improvement in external quantum efficiency and superior reliability of the pixel portion, the content of 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.

[0148] The third pixel portion 10c is a non-luminescent pixel portion (non-luminescent pixel portion) containing a cured product of the non-luminescent ink composition described above. The cured product does not contain luminescent nanoparticle composites, but contains light-scattering particles and a curing component. As shown in Figure 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 particle 12c may be the same as or different from the first light-scattering particle 12a and the second light-scattering particle 12b.

[0149] The third pixel portion 10c preferably has a transmittance of 30% or more for light in the wavelength range of 420 to 480 nm. In this case, the third pixel portion 10c can function as a blue pixel portion if a light source emitting light in the wavelength range of 420 to 480 nm is used. The transmittance of the third pixel portion 10c can be measured using a microspectroscopic device.

[0150] From the viewpoint of further reducing the difference in light intensity at the viewing angle, the content of light-scattering particles in the third pixel portion (non-emissive pixel portion) 10c is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on the total mass of the cured product of the non-emissive ink composition. From the viewpoint of further reducing light reflection, the content of light-scattering particles is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less, based on the total mass of the cured product of the non-luminescent ink composition.

[0151] 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.

[0152] The light-shielding section 20 is a partition (black matrix) provided to separate adjacent pixel sections to prevent color mixing (crosstalk) and to prevent light leakage from the light source. The constituent materials of the light-shielding portion 20 are not particularly limited, but include metals such as chromium, as well as resin compositions containing a binder resin and light-shielding particles such as carbon nanoparticles, metal oxides, inorganic pigments, and organic pigments. For the binder resin, for example, a resin containing one or more of the following can be used: polyimide resin, acrylic resin, epoxy resin, polyacrylamide, polyvinyl alcohol, gelatin, casein, cellulose, photosensitive resin, O / W emulsion resin (e.g., reactive silicone emulsion), etc. The thickness of the light-shielding portion 20 is preferably 1 to 30 μm.

[0153] The substrate 40 is a transparent substrate that is light-transmitting. For example, the substrate 40 can be a transparent glass substrate made of quartz glass, Pyrex® glass, synthetic quartz, etc., a transparent resin film, an optical resin film, or other transparent flexible substrate. In particular, it is preferable to use a glass substrate made of alkali-free glass that does not contain alkali components in the glass for the substrate 40. 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 materials have a low coefficient of thermal expansion and offer excellent dimensional stability and workability in high-temperature heat treatment.

[0154] The color filter 100, equipped with the above-described light conversion layer 30, can be suitably used in combination with a light source that emits light in the wavelength range of 420 to 480 nm.

[0155] 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 attaching an ink composition (inkjet ink) to the pixel portion formation area on the substrate 40 by an inkjet method, and curing the ink composition by irradiating it with active energy rays (for example, ultraviolet light). If the above-described luminescent ink composition is used as the ink composition, luminescent pixel portions are obtained, and if the non-luminescent ink composition is used, non-luminescent pixel portions are obtained.

[0156] The light-shielding portion 20 can be formed in a region that forms the boundary between multiple pixel portions on one surface of the substrate 40 by patterning a thin film of a metal such as chromium or a thin film of a resin composition containing light-shielding particles. Thin metal films can be formed, for example, by sputtering or vacuum deposition. Furthermore, thin films of resin compositions containing light-shielding particles can be formed, for example, by coating or printing. Methods for patterning include photolithography.

[0157] Examples of inkjet methods include the bubble jet (registered trademark) method, which uses an electrothermal converter as an energy generating element, and the piezo jet method, which uses a piezoelectric element. When an ink composition contains an organic solvent, it is preferable to remove at least a portion of the organic solvent during drying, and more preferably to remove all of it. The preferred method for drying the ink composition is drying under reduced pressure (vacuum drying). Vacuum drying is usually performed at a pressure of 1.0 to 500 Pa at 20 to 30°C for 3 to 30 minutes, from the viewpoint of controlling the composition of the ink composition.

[0158] The ink composition can be cured using, for example, a mercury lamp, a metal halide lamp, a xenon lamp, or an LED. The wavelength of the irradiated light is preferably 200-440 nm, and the exposure dose is 10-4000 mJ / cm². 2 It is preferable that this be the case.

[0159] When heat treatment (post-bake) of the cured product is performed to reduce outgassing by removing unreacted materials and to improve adhesion through thermal crosslinking, the heating temperature is preferably 110 to 250°C. The heating time is preferably 10 to 120 minutes.

[0160] Although an embodiment of the light conversion layer and color filter, as well as a method for manufacturing them, has been described above, the present invention is not limited to these. For example, the light conversion layer may include, in place of the third pixel portion 10c, or in addition to the third pixel portion 10c, a pixel portion (blue pixel portion) containing a cured product of a luminescent ink composition containing a blue light-emitting nanoparticle composite. Furthermore, the light conversion layer may include pixel portions (e.g., yellow pixel portions) containing a cured product of a luminescent ink composition that includes 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 an absorption maximum wavelength in the same wavelength range.

[0161] Furthermore, at least a portion of the pixel portion 10 of the light conversion layer 30 may be composed of a cured product of a composition containing pigments other than the luminescent nanoparticle composite. Furthermore, the color filter 100 may have an ink-repellent layer on the light-shielding portion 20 made of an ink-repellent material that is narrower than the light-shielding portion 20. Furthermore, instead of providing an ink-repellent layer, a photocatalyst-containing layer may be formed in a solid coating manner in the region including the pixel formation area, as a wettability variable layer. Then, the photocatalyst-containing layer may be exposed by irradiating it with light through a photomask to selectively increase the ink-hydrophilicity (wettability) of the pixel formation area. Examples of photocatalysts include titanium dioxide and zinc oxide.

[0162] The color filter 100 may include an ink receiving layer containing hydroxypropyl cellulose, polyvinyl alcohol, gelatin, etc., between the substrate 40 and the pixel portion 10. Furthermore, the color filter may 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 leaching into other layers. As the constituent material of the protective layer, known materials used as the protective layer of the color filter 100 can be used.

[0163] Furthermore, in the manufacture of the light conversion layer 30 and the color filter 100, the pixel portions may be formed by photolithography instead of inkjet. In this case, first, an ink composition is coated in layers onto 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 a pixel portion 10 made of cured ink composition. Since developing solutions are typically alkaline, alkali-soluble materials are used as the materials for the ink composition. However, from the viewpoint of material utilization efficiency, the inkjet method is superior to the photolithography method. This is because, by its principle, the photolithography method removes more than two-thirds of the material, resulting in material waste. For this reason, in this embodiment, it is preferable to use the ink composition as an inkjet ink and form the pixel portion by the inkjet method.

[0164] Furthermore, the pixel portion 10 of the light conversion layer 30 in this embodiment may also contain a pigment of approximately the same color as the light emission color of the light emission nanoparticle composite, in addition to the light emission nanoparticle composite described above. To include the pigment in the pixel portion 10, the pigment may be mixed into the ink composition.

[0165] Furthermore, one or two of the red light-emitting pixel portions (R), green light-emitting pixel portions (G), and blue light-emitting pixel portions (B) in the light conversion layer 30 of this embodiment may not contain a light-emitting nanoparticle composite, but may contain a colorant. Here, examples of usable colorants include, for example, diketopyrrolopyrrole pigments and / or anionic red organic dyes for the red light-emitting pixel portion (R). For the green light-emitting pixel portion (G), at least one selected from the group consisting of copper halide phthalocyanine pigments, phthalocyanine green dyes, and mixtures of phthalocyanine blue dyes and azo yellow organic dyes. For the blue light-emitting pixel portion (B), ε-type copper phthalocyanine pigments and / or cationic blue organic dyes are used. When these colorants are mixed into the light conversion layer 30, the amount used is preferably 1 to 5% by 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. [Examples]

[0166] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples. The compounds used in this example are shown below.

[0167] <Photopolymerizable compound> • HDDMA: 1,6-Hexanediol dimethacrylate (Product name: "NK Ester HD-N", manufactured by Shin Nakamura Chemical Industry 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: "Funkrill FA-512AS", manufactured by Showa Denko Materials Co., Ltd.) • DCPEM: Dicyclopentenyloxyethyl methacrylate (Product name: "Funkrill 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: "Noxellar BZ-P", manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) <Antioxidant> Agent 1: Bis(decyl)pentaerythritol diphosphite (Product name "JPE-10", manufactured by Johoku Chemical Industry Co., Ltd.) • Agent 2: Pentaerythritol tetrakis[3-[3,5-di(t-butyl)-4-hydroxyphenyl]propionate] (Product name "irganox 1010", manufactured by BASF Japan Ltd.)

[0168] <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 the mixture was heated under vacuum at 140°C for 2 hours. Next, 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 rapidly 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. Then, centrifugation was performed, and InP nanoparticles were obtained by draining the supernatant. Next, the obtained InP nanoparticles were dispersed in ODE. This yielded a dispersion (ODE dispersion) containing 5% by mass of InP nanoparticles.

[0169] (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 the mixture was heated under vacuum at 120°C 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 for 30 minutes under vacuum. Next, after raising the temperature to 200°C under a nitrogen atmosphere, 3 mL of the 0.4 M zinc precursor solution 1 obtained in (2-1) above and 0.8 mL of 1.0 M selenide trioctylphosphine (TOPSe) were added to the reaction flask, and the mixture was held at 200°C for 30 minutes to form a ZnSe shell. Next, 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. The temperature was then 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, centrifugation was performed, and by draining the supernatant, luminescent nanoparticles 1 with a core-shell structure (InP / ZnSe / ZnS) containing In and P in the core and having a ZnSe shell and a ZnS shell were obtained.

[0170] <Organic Ligand> Carboxylic acid compounds 1 to 16 were prepared as follows.

[0171] Carboxylic acid 1: 18 g (110 mmol, 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, and the mixture was washed once with 100 mL of 1N hydrochloric acid, and then twice with saturated saline solution. The organic layer was dried over magnesium sulfate and then concentrated to obtain carboxylic acid 1. Carboxylic acid 2: Using 110 mmol of diethylene glycol monophenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 2 was obtained in the same manner as in the preparation of carboxylic acid 1. Carboxylic acid 3: Carboxylic acid 3 was obtained using 110 mmol of diethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of succinic anhydride, 110 mmol of triethylamine, and 50 g of toluene, in the same manner as in the production of carboxylic acid 1. Carboxylic acid 4: Using 110 mmol of diethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 4 was obtained in the same manner as in the production of carboxylic acid 1. Carboxylic acid 5: Carboxylic acid 5 was obtained using 110 mmol of ethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, in the same manner as in the production of carboxylic acid 1. Carboxylic acid 6: Carboxylic acid 6 was obtained using 110 mmol of propylene glycol monophenyl ether (manufactured by Nippon Emulsifier Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, in the same manner as in the production of carboxylic acid 1. Carboxylic acid 7: Using 110 mmol of tetrahydrofurfuryl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 7 was obtained in the same manner as in the preparation of carboxylic acid 1. Carboxylic acid 8: Carboxylic acid 8 was obtained using 110 mmol of glycerol formal (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, in the same manner as in the preparation of carboxylic acid 1. Carboxylic acid 9: 19 g (100 mmol, 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, and the mixture was washed once with 100 mL of 1N hydrochloric acid, and then twice with saturated saline solution. The organic layer was dried over magnesium sulfate and then concentrated to obtain carboxylic acid 9. Carboxylic acid 10: Using 100 mmol of tetrahydrofurfuryl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 105 mmol of 3-mercaptopropionic acid, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 10 was obtained in the same manner as in the preparation of carboxylic acid 9. Carboxylic acid 11: Using 110 mmol of triethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of succinic anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 11 was obtained in the same manner as in the production of carboxylic acid 1. Carboxylic acid 12: Using 110 mmol of polyethylene glycol monomethyl ether (Merck), which has a number-average molecular weight of 350, 100 mmol of succinic anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 12 was obtained in the same manner as in the preparation of carboxylic acid 1. Carboxylic acid 13: Using 110 mmol of tetraethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of succinic anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 13 was obtained in the same manner as in the production of carboxylic acid 1. Carboxylic acid 14: Using 110 mmol of hexaethylene glycol monobenzyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 14 was obtained in the same manner as in the production of carboxylic acid 1. Carboxylic acid 15: Using 110 mmol of triethylene glycol monomethyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of cis-1,2-cyclohexanedicarboxylic acid anhydride glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 15 was obtained in the same manner as in the preparation of carboxylic acid 1. Carboxylic acid 16: Using 110 mmol of diethylene glycol monophenyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 mmol of cis-1,2-cyclohexanedicarboxylic acid anhydride glutaric acid anhydride, 110 mmol of triethylamine, and 50 g of toluene, carboxylic acid 16 was obtained in the same manner as in the preparation of carboxylic acid 1. The chemical structures of the obtained carboxylic acids 1 to 16 are shown. [ka]

[0172] [Manufacturing 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 the mixture was stirred at 80°C for 3 hours under a nitrogen atmosphere. After cooling the reaction solution to room temperature, 10 ml of acetone and 60 ml of heptane were added to reprecipitate the compound. Subsequently, centrifugation was performed, and the luminescent nanoparticle composite A-1 was obtained by sedation of the supernatant.

[0173] [Examples 2-10, Comparative Examples 1-6] Except for changing the types of luminescent nanoparticles and organic ligands as shown in Table 1, the same procedure as in Example 1 was performed to obtain luminescent nanoparticle complexes A-2 to A-10 and B-1 to B-4. In Comparative Examples 5 and 6, reprecipitation was not possible, and luminescent nanoparticle complexes were not obtained. It is thought that carboxylic acids 15 and 16, which have substituents at the α-position of the carboxyl group, could not be reprecipitated in the acetone-heptane mixed solvent because the ligand exchange reaction did not proceed sufficiently due to steric hindrance caused by the substituents. Table 1 shows the δD values and molecular weights of the organic ligands used. The δD values of the Hansen solubility parameters were estimated using HSPiP. The number average molecular weight of the organic ligand with a molecular weight distribution was 1 determined from the integration ratio of HNMR.

[0174] [Table 1]

[0175] <Production of Light-Scattering Particle Dispersion> In a container filled with argon gas, 33.0 g of titanium oxide (product name: CR-60-2, manufactured by Ishihara Sangyo Co., Ltd., average particle diameter (volume average diameter): 210 nm), 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. Thereafter, zirconia beads (diameter: 1.25 mm) were added to the obtained mixture, and the mixture was dispersed by shaking for 2 hours using a paint conditioner, and the zirconia beads were removed using a polyester mesh filter to obtain a light-scattering particle dispersion (titanium oxide content: 55% by mass).

[0176] 1. Preparation of Ink Composition <Ink Composition 1> The luminescent nanoparticle composite A-1, a photopolymerizable compound, a photoinitiator, the light-scattering particle dispersion, and an antioxidant were blended so that the content of each component was the amount shown in Table 2 (unit: part by mass), and uniformly mixed in a container filled with argon gas. Thereafter, in a glove box, the mixture was filtered through a filter with a pore size of 5 μm. Furthermore, argon gas was introduced into the container containing the obtained filtrate, and the inside of the container was saturated with argon gas. Next, the pressure was reduced to remove argon gas, thereby obtaining Ink Composition 1.

[0177] <Ink compositions 2-20> Each luminescent nanoparticle composite was combined with a photopolymerizable compound, a photopolymerization initiator, a light-scattering particle dispersion, a dithiocarbamate compound, and an antioxidant in the amounts (parts by mass) shown in Table 2, and ink compositions 2 to 20 were obtained in the same manner as ink composition 1.

[0178] 2. Evaluation of the ink composition 2-1. Preparation of samples for external quantum efficiency evaluation Each ink composition was coated onto a glass substrate using a spin coater in air to a film thickness of 10 μm. The coated film was subjected to UV irradiation under a nitrogen atmosphere using an LED lamp with a main wavelength of 395 nm, accumulating light intensity of 1000 mJ / cm². 2 The ink composition was cured by UV irradiation to form a layer (photoconversion layer) on the glass substrate. This created an evaluation sample, which was a substrate having a photoconversion layer.

[0179] 2-2. Measurement of External Quantum Efficiency (EQE) A blue LED (manufactured by CCS Corporation) emitting light with an emission peak at a wavelength of 450 nm was used as a surface-emitting light source. The measurement device consisted of 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 a blue LED and an integrating sphere, and the spectrum observed and the illuminance at each wavelength were measured while the blue LED was turned on.

[0180] The external quantum efficiency (EQE) was determined from the spectrum and illuminance measured by the above measuring device as follows. EQE (Emission Emission Value) is a value that indicates the proportion of light (photons) incident on the photoconversion layer that is emitted as fluorescence towards the observer. Therefore, a higher EQE value indicates that the photoconversion layer has excellent emission characteristics and is an important evaluation indicator. EQE(%) = P1(Green) / E(Blue) × 100

[0181] Here, E (Blue) and P1 (Green) represent the following values, respectively. E (Blue) represents the sum of "illuminance × wavelength ÷ hc" in the wavelength range of 380 to 490 nm. P1 (Green) represents the sum of "illuminance × wavelength ÷ hc" in the wavelength range of 500 to 650 nm. These values ​​correspond to the number of photons observed. Note that h represents Planck's constant and c represents the speed of light.

[0182] 2-3. Heat resistance Each evaluation sample prepared in 2-1 was transferred to a 180°C hot plate placed in a glove box under a nitrogen atmosphere and heated for 30 minutes. After the evaluation samples cooled to room temperature, the EQE was measured in the same manner as in 2-2, and the EQE retention rate was calculated using the following formula. The heat resistance was then evaluated according to the following criteria. Maintenance rate = [EQE after heating] / [EQE before heating] × 100 [Evaluation Criteria] ◎: 98% or higher ○: 95% or more, less than 98% △: 90% or more, less than 95% ×: Less than 90%

[0183] 2-4. Atmospheric storage stability (atmospheric stability) Each evaluation sample prepared in 2-3 was left in the air under the illumination of the yellow room for 24 hours, and then the EQE was measured in the same manner as in 2-2. The maintenance ratio of the EQE after irradiation relative to the EQE before irradiation was calculated using the following formula, and atmospheric stability was evaluated according to the following criteria. Maintenance rate = [EQE after 24 hours] / [Initial EQE] × 100 [Evaluation Criteria] ◎: 98% or higher ○: 95% or more, less than 98% △: 90% or more, less than 95% ×: Less than 90%

[0184] 2-5. Viscosity of the 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] ◎: 12 mPa·s or less 〇: Exceeding 12 mPa·s and 13 mPa·s or less △: Exceeding 13 mPa·s and 14 mPa·s or less ×: Exceeding 14 mPa·s

[0185] 2-6. Storage Stability of Ink Composition The ink composition prepared in 1 was stored in a constant temperature tester maintained at 40°C for 2 weeks, and then the viscosity of the ink composition was measured. The thickening rate of the ink composition was determined by the following formula, and the storage stability was evaluated according to the following criteria. Thickening rate = ([Viscosity after 2 weeks] - [Initial viscosity]) / [Initial viscosity] × 100 [Evaluation Criteria] ◎: Thickening is 3% or less 〇: Thickening exceeds 3% and is 5% or less △: Thickening exceeds 5% The above evaluation results are shown in Table 2.

[0186]

Table 2

Industrial Applicability

[0187] The luminescent nanoparticle composite of the present invention is excellent in air storage stability and heat resistance. From an ink composition containing such a luminescent nanoparticle composite, a light conversion layer excellent in luminescence characteristics, and a color filter used in portable terminals, televisions, monitors, etc. can be provided, and it is useful as a liquid crystal display device or a self-emitting display device.

Explanation of Signs

[0188] 10 Pixel portion 10a First pixel portion 10b Second pixel portion 10c Third pixel portion 11a First luminescent nanoparticle composite 11b Second luminescent nanoparticle composite 12a First light scattering particle 12b Second light scattering particle 12c Third light scattering particle 20 Light-shielding part 30 Light conversion layer 40 Base material 100 Color Filters

Claims

1. A luminescent nanoparticle composite in which an organic ligand is coordinated to the surface of luminescent nanoparticles, A luminescent nanoparticle composite characterized in that the organic ligand is represented by the following formula (1). 【Chemistry 1】 [In formula (1), R １ This represents an alkylene group having 1 to 6 carbon atoms, and one -H in the alkylene group ２ The - is replaced by -OCO-, or two or more non-adjacent -CH groups in the alkylene group. ２ - one of -CH ２ The - is replaced by -OCO-, and the remaining -CH ２ - is replaced by at least one of -O-, -S-, -CO-, -OCO-, -NH-, -CONH- or -NHCO-, R ２ [wherein X represents an alkylene group or (poly)oxyalkylene group having 1 to 10 carbon atoms, and X represents a substituent having a cyclic structure.]

2. Two non-adjacent -CH in the alkylene group ２ - One of the two -CH ２ - is replaced by -OCO-, and the remaining -CH ２ - is replaced by -S-. The luminescent nanoparticle composite according to claim 1.

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 formula (1) is an aryl group.

5. The luminescent nanoparticle composite according to any one of claims 1 to 3, wherein the δD value of the Hansen solubility parameter of the organic ligand is 17.4 MPa 0.5 or higher.

6. The luminescent nanoparticle composite according to any one of claims 1 to 5, wherein the luminescent nanoparticles are core-shell structured luminescent nanoparticles containing indium and phosphorus in the core.

7. An ink composition comprising a 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 photoradical polymerizable 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 containing an antioxidant.

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

12. An ink composition according to any one of claims 7 to 11, used in an inkjet droplet ejection method.

13. An ink composition according to any one of claims 7 to 12, for use as a color filter.

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

15. A light conversion layer comprising multiple pixel portions, The photoconversion layer has a plurality of pixel portions, each containing a cured product of the ink composition described in any one of claims 7 to 13.

16. The light-shielding portion is further provided between the plurality of pixel portions, The plurality of pixel portions include the cured product and the luminescent nanoparticle composite, which absorbs light with wavelengths in the range of 420 to 480 nm and emits light having an emission peak wavelength in the range of 605 to 665 nm, and a first pixel portion, The cured product is included, and the luminescent nanoparticle composite is in the range of 420 to 480 nm. It absorbs light of a certain wavelength and emits light with an emission peak wavelength in the range of 500 to 560 nm. A second pixel portion containing a photosensitive nanoparticle composite, The optical conversion layer according to claim 15, having the above characteristics.

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

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