Inkjet ink composition for color filters, cured product, photoconversion layer, and color filter

Abstract

To provide a color filter inkjet ink composition which can form a color filter pixel part having excellent external quantum efficiency, while containing luminescent nanocrystal particles and light-scattering particles, and also demonstrates excellent re-dispersibility.SOLUTION: A color filter inkjet ink composition contains luminescent nanocrystal particles, an organic ligand capable of bonding with the surfaces of the luminescent nanocrystal particles, light-scattering particles, a polymer dispersant, and a photopolymerizable compound, the content of the organic ligand being 15-50 pts.mass with respect to 100 pts.mass of the luminescent nanocrystal particles, and the content of the polymer dispersant being 3-15 pts.mass with respect to 100 pts.mass of the light-scattering particles.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an inkjet ink composition for a color filter, a cured product, a light conversion layer, and a color filter.

Background Art

[0002] Conventionally, color filters used in displays have been manufactured by a photolithography method using a curable resist material containing, for example, red organic pigment particles or green organic pigment particles, an alkali-soluble resin, and / or an acrylic monomer.

[0003] In recent years, as there has been a strong demand for lower power consumption in displays, instead of the above red organic pigment particles or green organic pigment particles, for example, light-emitting nanocrystal particles such as quantum dots, quantum rods, and other inorganic phosphor particles are used to form pixel portions such as red pixels and green pixels, and methods for doing so have been actively studied (for example, Patent Document 1).

[0004] By the way, in the method for manufacturing a color filter by the above photolithography method, due to the characteristics of the manufacturing method, there has been a drawback that the resist material other than the pixel portion including relatively expensive light-emitting nanocrystal particles is wasted. Under such circumstances, in order to eliminate the waste of the resist material as described above, forming a light conversion layer using a curable ink composition by an inkjet method (inkjet system) has begun to be studied.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] From the standpoint of light conversion efficiency, inkjet ink compositions for color filters sometimes contain light-scattering particles along with luminescent nanocrystalline particles. However, in ink compositions containing both luminescent nanocrystalline particles and light-scattering particles, the inorganic particle components tend to aggregate during storage, which can reduce the ability to homogeneously redisperse them during use, or so-called redispersibility.

[0007] The problem that the present invention aims to solve is to provide an inkjet ink composition for color filters that contains luminescent nanocrystalline particles and light-scattering particles, can form a color filter pixel portion having excellent external quantum efficiency, and has excellent redispersibility. [Means for solving the problem]

[0008] Through our investigations, we have found that by incorporating specific amounts of an organic ligand and a polymer dispersant, which can bind to the surface of the luminescent nanocrystalline particles, into an inkjet ink composition for color filters containing luminescent nanocrystalline particles and light-scattering particles, it is possible to obtain an inkjet ink composition for color filters that can form color filter pixel portions with excellent external quantum efficiency while containing luminescent nanocrystalline particles and light-scattering particles, and that also exhibits excellent redispersibility.

[0009] One aspect of the present invention relates to an inkjet ink composition for color filters, comprising luminescent nanocrystalline particles, an organic ligand capable of binding to the surface of the luminescent nanocrystalline particles, light-scattering particles, a polymeric dispersant, and a photopolymerizable compound, wherein the content of the organic ligand is 15 to 50 parts by mass per 100 parts by mass of the luminescent nanocrystalline particles, and the content of the polymeric dispersant is 3 to 15 parts by mass per 100 parts by mass of the light-scattering particles.

[0010] It is preferable that the molecular weight of the organic ligand is 1000 or less.

[0011] It is preferable that the weight-average molecular weight of the polymeric dispersant is 1000 or more. It is preferable that the polymeric dispersant has both an acid value and an amine value. It is preferable that the polymeric dispersant contains two or more types of polymeric dispersants.

[0012] The average particle size of the light-scattering particles is preferably 0.15 μm or more and 0.5 μm or less.

[0013] One aspect of the present invention relates to the cured product of the inkjet ink composition for color filters described above.

[0014] One aspect of the present invention relates to a light conversion layer comprising a plurality of pixel portions and light-shielding portions provided between the plurality of pixel portions, wherein the plurality of pixel portions have light-emitting pixel portions containing a cured product of the above-mentioned inkjet ink composition for color filters.

[0015] The light conversion layer may include a first luminescent pixel portion containing luminescent nanocrystalline particles that absorb light with wavelengths in the range of 420 to 480 nm and emit light having an emission peak wavelength in the range of 605 to 665 nm, and a second luminescent pixel portion containing luminescent nanocrystalline particles that absorb light with wavelengths in the range of 420 to 480 nm and emit light having an emission peak wavelength in the range of 500 to 560 nm.

[0016] One aspect of the present invention relates to a color filter comprising the above-mentioned light conversion layer. [Effects of the Invention]

[0017] According to one aspect of the present invention, it is possible to provide an inkjet ink composition for color filters that contains luminescent nanocrystalline particles and light-scattering particles, can form a color filter pixel portion having excellent external quantum efficiency, and also has excellent redispersibility. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 is a schematic cross-sectional view of a color filter according to one embodiment of the present invention. [Embodiments for Carrying out the Invention]

[0019] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the "cured product of the ink composition" is obtained by curing the curable component in the ink composition (when the ink composition contains a solvent component, the ink composition after drying). Therefore, it is preferable that the cured product of the ink composition does not contain an organic solvent, but a part of the organic solvent that has not been completely dried may remain. Also, in this specification, the "non-volatile content of the ink composition" means a component other than the organic solvent contained in the ink composition. That is, the "non-volatile content of the ink composition" may be rephrased as the component before curing to be contained in the cured product of the ink composition.

[0020] [Inkjet Ink Composition for Color Filter] An inkjet ink composition for a color filter according to one embodiment (hereinafter, also simply referred to as an "ink composition") contains luminescent nanocrystal particles, an organic ligand capable of binding to the surface of the luminescent nanocrystal particles, light-scattering particles, a polymer dispersant, and a photopolymerizable compound.

[0021] The above ink composition is, for example, an ink composition for forming a light conversion layer (pixel portion of the light conversion layer) of a color filter, and is used for forming a light conversion layer (for example, for forming a pixel portion of a color filter). This ink composition is a composition used in an inkjet method. The ink composition according to one embodiment can contribute to making the inkjet method a low-cost process compared to the photolithography method in that it can form a pixel portion (light conversion layer) without wasting expensive luminescent nanocrystal particles, an inkjet head, etc. Hereinafter, an embodiment of the ink composition will be described by taking an ink composition used for forming a light conversion layer by an inkjet method as an example.

[0022] [Luminescent Nanocrystal Particles] The luminescent nanocrystal particles are nanosized crystals that absorb excitation light and emit fluorescence or phosphorescence, and are, for example, crystals having a maximum particle diameter of 100 nm or less measured by a transmission electron microscope or a scanning electron microscope.

[0023] The luminescent nanocrystal particles can emit light (fluorescence or phosphorescence) having a wavelength different from the absorbed wavelength by, for example, absorbing light of a predetermined wavelength. The luminescent nanocrystal particles are preferably red luminescent nanocrystal particles (red luminescent nanocrystal particles) that emit light (red light) having an emission peak wavelength in the range of 605 to 665 nm, green luminescent nanocrystal particles (green luminescent nanocrystal particles) that emit light (green light) having an emission peak wavelength in the range of 500 to 560 nm, or blue luminescent nanocrystal particles (blue luminescent nanocrystal particles) that emit light (blue light) having an emission peak wavelength in the range of 420 to 480 nm. In the present embodiment, it is preferable that the ink composition contains at least one of these luminescent nanocrystal particles. Further, the light absorbed by the luminescent nanocrystal particles is preferably light (blue light) having a wavelength in the range of 400 nm or more and less than 500 nm (particularly, light having a wavelength in the range of 420 to 480 nm), or light (ultraviolet light) having a wavelength in the range of 200 nm to 400 nm. The emission peak wavelength of the luminescent nanocrystal particles can be confirmed, for example, in a fluorescence spectrum or a phosphorescence spectrum measured using a spectrofluorometer.

[0024] The red-emitting nanocrystalline particles preferably have an emission peak wavelength of 665 nm or less, 663 nm or less, 660 nm or less, 658 nm or less, 655 nm or less, 653 nm or less, 651 nm or less, 650 nm or less, 647 nm or less, 645 nm or less, 643 nm or less, 640 nm or less, 637 nm or less, 635 nm or less, 632 nm or less, or 630 nm or less, and preferably have an emission peak wavelength of 628 nm or more, 625 nm or more, 623 nm or more, 620 nm or more, 615 nm or more, 610 nm or more, 607 nm or more, or 605 nm or more. These upper and lower limits can be combined arbitrarily. In the same descriptions below, the upper and lower limits described individually can also be combined arbitrarily.

[0025] The green-emitting nanocrystalline particles preferably have an emission peak wavelength of 560 nm or less, 557 nm or less, 555 nm or less, 550 nm or less, 547 nm or less, 545 nm or less, 543 nm or less, 540 nm or less, 537 nm or less, 535 nm or less, 532 nm or less, or 530 nm or less, and preferably have an emission peak wavelength 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.

[0026] The blue-emitting nanocrystalline particles preferably have an emission peak wavelength 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 an emission peak wavelength 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.

[0027] The wavelength (emission color) of light emitted by luminescent nanocrystalline particles depends on the size (e.g., particle diameter) of the luminescent nanocrystalline particles, according to the solution to the Schrödinger wave equation in the square-well model, but also on the energy gap of the luminescent nanocrystalline particles. Therefore, the emission color can be selected by changing the constituent material and size of the luminescent nanocrystalline particles used.

[0028] The luminescent nanocrystalline particles are preferably luminescent nanocrystalline particles containing a semiconductor material (luminescent semiconductor nanocrystalline particles). Examples of luminescent semiconductor nanocrystalline particles include quantum dots and quantum rods. Among these, quantum dots are preferred because they allow for easy control of the emission spectrum, ensure reliability, reduce production costs, and improve mass productivity.

[0029] The luminescent semiconductor nanocrystalline particles may consist only of a core containing a first semiconductor material, or they may have a core containing a first semiconductor material and a shell containing a second semiconductor material different from the first semiconductor material and covering at least a part of the core. In other words, the structure of the luminescent semiconductor nanocrystalline particles is preferably a structure consisting only of a core (core structure) or a structure consisting of a core and a shell (core / shell structure). Furthermore, in addition to the shell containing the second semiconductor material (first shell), the luminescent semiconductor nanocrystalline particles may further have a shell (second shell) containing a third semiconductor material different from the first and second semiconductor materials and covering at least a part of the core. In other words, the structure of the luminescent semiconductor nanocrystalline particles is preferably a structure consisting of a core, a first shell, and a second shell (core / shell / shell structure). Each of the core and shell can be a mixed crystal containing two or more semiconductor materials (e.g., CdSe+CdS, CIS+ZnS, etc.).

[0030] The luminescent nanocrystalline particles preferably contain 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.

[0031] Specific semiconductor materials include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, CdHgZnTe , CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe; GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, Al PAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb;SnS, SnSe, SnTe, PbS, PbSe Examples include PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; Si, Ge, SiC, SiGe, AgInSe2, CuGaSe2, CuInS2, CuGaS2, CuInSe2, AgInS2, AgGaSe2, AgGaS2, C, Si, and Ge. 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 semiconductor nanocrystalline particles include at least one 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, AgGaS2, AgGaSe2, AgGaTe2, CuInS2, CuInSe2, CuInTe2, CuGaS2, CuGaSe2, CuGaTe2, Si, C, Ge, and Cu2ZnSnS4.

[0032] Examples of red-emitting semiconductor nanocrystalline particles include CdSe nanocrystalline particles, nanocrystalline particles having a core / shell structure in which the shell portion is CdS and the inner core portion is CdSe, nanocrystalline particles having a core / shell structure in which the shell portion is CdS and the inner core portion is ZnSe, nanocrystalline particles of a mixed crystal of CdSe and ZnS, nanocrystalline particles of InP, nanocrystalline particles having a core / shell structure in which the shell portion is ZnS and the inner core portion is InP, and nanocrystalline particles having a core / shell structure. Examples include nanocrystalline particles in which the shell portion is a mixed crystal of ZnS and ZnSe and the inner core portion is InP, nanocrystalline particles of a mixed crystal of CdSe and CdS, nanocrystalline particles of a mixed crystal of ZnSe and CdS, nanocrystalline particles having a core / shell / shell structure in which the first shell portion is ZnSe, the second shell portion is ZnS and the inner core portion is InP, and nanocrystalline particles having a core / shell / shell structure in which the first shell portion is a mixed crystal of ZnS and ZnSe, the second shell portion is ZnS and the inner core portion is InP, and so on.

[0033] Examples of green-emitting semiconductor nanocrystalline particles include CdSe nanocrystalline particles, mixed crystal nanocrystalline particles of CdSe and ZnS, nanocrystalline particles having a core / shell structure in which the shell portion is ZnS and the inner core portion is InP, nanocrystalline particles having a core / shell structure in which the shell portion is a mixed crystal of ZnS and ZnSe and the inner core portion is InP, nanocrystalline particles having a core / shell / shell structure in which the first shell portion is ZnSe, the second shell portion is ZnS and the inner core portion is InP, and nanocrystalline particles having a core / shell / shell structure in which the first shell portion is a mixed crystal of ZnS and ZnSe, the second shell portion is ZnS and the inner core portion is InP.

[0034] Examples of blue-emitting semiconductor nanocrystalline particles include ZnSe nanocrystalline particles, ZnS nanocrystalline particles, nanocrystalline particles having a core / shell structure in which the shell portion is ZnSe and the inner core portion is ZnS, CdS nanocrystalline particles, nanocrystalline particles having a core / shell structure in which the shell portion is ZnS and the inner core portion is InP, nanocrystalline particles having a core / shell structure in which the shell portion is a mixed crystal of ZnS and ZnSe and the inner core portion is InP, nanocrystalline particles having a core / shell / shell structure in which the first shell portion is ZnSe, the second shell portion is ZnS and the inner core portion is InP, and nanocrystalline particles having a core / shell / shell structure in which the first shell portion is a mixed crystal of ZnS and ZnSe, the second shell portion is ZnS and the inner core portion is InP.

[0035] Semiconductor nanocrystalline particles, while maintaining the same chemical composition, can emit light in a color ranging from red to green by changing their average particle size. Furthermore, it is preferable to use semiconductor nanocrystalline particles that have minimal adverse effects on the human body. When using semiconductor nanocrystalline particles containing cadmium, selenium, etc., as luminescent nanocrystalline particles, it is preferable to select semiconductor nanocrystalline particles that contain as little of the above elements (cadmium, selenium, etc.) as possible and use them alone, or to use them in combination with other luminescent nanocrystalline particles in a way that minimizes the amount of the above elements.

[0036] The shape of the luminescent nanocrystalline particles is not particularly limited and may be any geometric shape or any irregular shape. Examples of luminescent nanocrystalline particle shapes include spherical, ellipsoidal, pyramidal, disc-shaped, branch-shaped, network-shaped, and rod-shaped particles. However, it is preferable to use particles with less directionality as luminescent nanocrystalline particles (for example, spherical or tetrahedral particles) in order to further improve the uniformity and fluidity of the ink composition.

[0037] The average particle diameter (volume average diameter) of the luminescent nanocrystalline particles is preferably 1 nm or more, 1.5 nm or more, or 2 nm or more, from the viewpoint of easily obtaining emission at a desired wavelength, and from the viewpoint of excellent dispersibility and storage stability. From the viewpoint of easily obtaining a desired emission wavelength, the average particle diameter (volume average diameter) of the luminescent nanocrystalline particles is preferably 40 nm or less, 30 nm or less, or 20 nm or less. The average particle diameter (volume average diameter) of the luminescent nanocrystalline particles is obtained by measuring it with a transmission electron microscope or a scanning electron microscope and calculating the volume average diameter.

[0038] As the luminescent nanocrystalline particles, those dispersed in a colloidal form within a photopolymerizable compound or the like can be used. Preferably, the surface of the dispersed luminescent nanocrystalline particles is passivated by the organic ligand described above.

[0039] Commercially available luminescent nanocrystalline particles can be used. Examples of commercially available luminescent nanocrystalline particles include indium phosphide / zinc sulfide, D-dot, CuInS / ZnS from NN-Labs, and InP / ZnS from Aldrich.

[0040] The content of luminescent nanocrystalline particles is preferably 10 parts by mass or more, 15 parts by mass or more, 20 parts by mass or more, or 25 parts by mass or more, per 100 parts by mass of the non-volatile content of the ink composition. A notable feature of the present invention is that it is possible to achieve excellent compatibility with inkjet processes while increasing the content of luminescent nanocrystalline particles. On the other hand, the content of luminescent nanocrystalline particles is preferably 50 parts by mass or less, 45 parts by mass or less, or 40 parts by mass or less, per 100 parts by mass of the non-volatile content of the ink composition. In this specification, the content of luminescent nanocrystalline particles refers only to the content of the luminescent nanocrystalline particles themselves, and does not include the content of organic ligands, even if the luminescent nanocrystalline particles have organic ligands.

[0041] The ink composition may contain two or more types of luminescent nanocrystalline particles, including red luminescent nanocrystalline particles, green luminescent nanocrystalline particles, and blue luminescent nanocrystalline particles, but preferably contains only one type of these particles. When the ink composition contains red luminescent nanocrystalline particles, the content of green luminescent nanocrystalline particles and blue luminescent nanocrystalline particles is preferably 10% by mass or less, and more preferably 0% by mass, based on the total mass of the luminescent nanocrystalline particles. When the ink composition contains green luminescent nanocrystalline particles, the content of red luminescent nanocrystalline particles and blue luminescent nanocrystalline particles is preferably 10% by mass or less, and more preferably 0% by mass, based on the total mass of the luminescent nanocrystalline particles.

[0042] [organic ligand] Organic ligands are present near the surface of luminescent nanocrystalline particles and have the function of dispersing the luminescent nanocrystalline particles. Organic ligands have, for example, functional groups (hereinafter also simply referred to as "affinity groups") to ensure affinity with photopolymerizable compounds, and functional groups that can bind to luminescent nanocrystalline particles (functional groups to ensure adsorption to luminescent nanocrystalline particles), and are present near the surface of luminescent nanocrystalline particles by coordinating with the surface of the luminescent nanocrystalline particles.

[0043] The affinity group is preferably a substituted or unsubstituted aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear or branched. The aliphatic hydrocarbon group may have unsaturated bonds or not. A substituted aliphatic hydrocarbon may be a group in which some carbon atoms of an aliphatic hydrocarbon group are substituted with oxygen atoms. A substituted aliphatic hydrocarbon group may include, for example, a (poly)oxyalkylene group. Here, "(poly)oxyalkylene group" means at least one of an oxyalkylene group and a polyoxyalkylene group in which two or more alkylene groups are linked by ether bonds.

[0044] Examples of functional groups that can bind to luminescent nanocrystalline particles include hydroxyl groups, amino groups, carboxyl groups, thiol groups, phosphate groups, phosphonic acid groups, phosphine groups, phosphine oxide groups, and alkoxysilyl groups.

[0045] The molecular weight of the organic ligand is preferably 1000 or less, and more preferably 800 or less, 700 or less, 600 or less, or 500 or less. For example, the molecular weight of the organic ligand is preferably 100 or more, or 200 or more. When the molecular weight of the organic ligand is within the above range, the viscosity as an inkjet ink becomes even better.

[0046] Examples of 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).

[0047] In one embodiment, the organic ligand is preferably an organic ligand represented by the following formula (1-1).

[0048] [ka] [In equation (1-1), p represents an integer between 0 and 50, and q represents an integer between 0 and 50.]

[0049] In the organic ligand represented by formula (1-1), it is preferable that at least one of p and q is 1 or more, and more preferable that both p and q are 1 or more.

[0050] The organic ligand may be, for example, an organic ligand represented by the following formula (1-2).

[0051] [ka]

[0052] In formula (1-2), A 1 This indicates a monovalent group containing a carboxyl group, A 2 r represents a monovalent group containing a hydroxyl group, R represents a hydrogen atom, a methyl group, or an ethyl group, L represents a substituted or unsubstituted alkylene group, and r represents an integer of 0 or more. The number of carboxyl groups in a monovalent group containing a carboxyl group is preferably two or more, more preferably two to four, and even more preferably two. The number of carbon atoms in the alkylene group represented by L is preferably, for example, 1 to 10. The alkylene group represented by L may have some of its carbon atoms substituted with heteroatoms, or may be substituted with at least one heteroatom selected from the group consisting of oxygen atoms, sulfur atoms, and nitrogen atoms. r is preferably, for example, an integer from 1 to 100, or an integer from 10 to 20.

[0053] The organic ligand is preferably an organic ligand represented by the following formula (1-2A).

[0054] [ka]

[0055] In equation (1-2A), r is equivalent to the above.

[0056] In one embodiment, the organic ligand is preferably an organic ligand represented by the following formula (1-3).

[0057] [ka]

[0058] In formula (1-3), n represents an integer from 0 to 50, and m represents an integer from 0 to 50. n is preferably from 0 to 20, more preferably from 0 to 10. m is preferably from 0 to 20, more preferably from 0 to 10. It is preferable that at least one of n and m is 1 or more. That is, it is preferable that n+m is 1 or more. n+m may be 10 or less. Z represents a substituted or unsubstituted alkylene group. The number of carbon atoms in the alkylene group may be, for example, 1 to 10. The alkylene group represented by Z may have some carbon atoms substituted with heteroatoms, or may be substituted with at least one heteroatom selected from the group consisting of oxygen atoms, sulfur atoms, and nitrogen atoms.

[0059] In one embodiment, the organic ligand is preferably an organic ligand represented by the following formula (1-4).

[0060] [ka] [In equations (1-4), l represents an integer between 1 and 50.]

[0061] In the organic ligand represented by formula (1-4), l is preferably 1 to 20, 3 to 15, 5 to 10, or 7.

[0062] The content of organic ligands in the ink composition is 15 to 50 parts by mass per 100 parts by mass of luminescent nanocrystalline particles. The lower limit of the content of organic ligands in the ink composition is preferably 16 parts by mass or more, 17 parts by mass or more, 18 parts by mass or more, 19 parts by mass or more, 20 parts by mass or more, 21 parts by mass or more, 22 parts by mass or more, or 23 parts by mass or more per 100 parts by mass of luminescent nanocrystalline particles, from the viewpoint of further suppressing aggregation of components in the ink composition, further improving the effect of suppressing leak light and improving external quantum efficiency, and further improving redispersibility. The upper limit of the content of organic ligands in the ink composition is preferably 48 parts by mass or less, 46 parts by mass or less, 44 parts by mass or less, 42 parts by mass or less, 40 parts by mass or less, 38 parts by mass or less, or 36 parts by mass or less per 100 parts by mass of luminescent nanocrystalline particles, from the viewpoint of further suppressing phase separation and / or the generation of gel-like substances and further improving redispersibility. From the viewpoint of further superiority in suppressing light leakage and improving external quantum efficiency, as well as from the viewpoint of further superior redispersibility, the content of the organic ligand in the ink composition is preferably, for example, 18 to 45 parts by mass, 20 to 40 parts by mass, or 22 to 35 parts by mass per 100 parts by mass of luminescent nanocrystalline particles.

[0063] [Light scattering particles] Light-scattering particles are, for example, optically inert inorganic fine particles. When an ink composition contains light-scattering particles, it can scatter light from a light source irradiated onto the pixel area, thereby obtaining excellent optical properties.

[0064] 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; metal oxides such as silica, barium sulfate, barium carbonate, calcium carbonate, talc, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, alumina white, titanium oxide, magnesium oxide, barium oxide, aluminum oxide, bismuth oxide, zirconium oxide, and zinc oxide; metal carbonates such as magnesium carbonate, barium carbonate, bismuth subcarbonate, and calcium carbonate; metal 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 bismuth subnitrate. The light-scattering particles preferably contain at least one selected from the group consisting of titanium dioxide, alumina, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate, barium titanate, and silica, from the viewpoint of excellent discharge stability and superior effect in improving external quantum efficiency, and more preferably contain at least one selected from the group consisting of titanium dioxide, zirconium oxide, zinc oxide, and barium titanate.

[0065] The shape of the light-scattering particles may be spherical, filamentous, or irregular. However, it is preferable to use particles with less directionality as light-scattering particles (for example, spherical or tetrahedral particles) because this can further improve the uniformity, fluidity, and light scattering properties of the ink composition, and provide excellent discharge stability.

[0066] The average particle size of light-scattering particles in the ink composition is preferably 0.15 μm or more and 0.5 μm or less. The average particle size (volume average diameter) of light-scattering particles in the ink composition is preferably, for example, 0.16 μm or more and 0.4 μm or less, 0.17 μm or more and 0.3 μm or less, or 0.18 μm or more and 0.25 μm or less. When the average particle size of light-scattering particles in the ink composition is within the above range, the ejection stability of the inkjet ink becomes even better. In this specification, the average particle size (volume average diameter) of light-scattering particles in the ink composition is obtained by measuring with a dynamic light-scattering nanotrack particle size analyzer and calculating the volume average diameter.

[0067] The content of light-scattering particles is preferably 0.1 parts by mass or more, 1 part by mass or more, 2 parts by mass or more, or 3 parts by mass or more, per 100 parts by mass of the nonvolatile content of the ink composition. The content of light-scattering particles is preferably less than 10 parts by mass, 9 parts by mass or less, 7 parts by mass or less, or 5 parts by mass or less, per 100 parts by mass of the nonvolatile content of the ink composition.

[0068] The mass ratio of light-scattering particles to luminescent nanocrystalline particles (light-scattering particles / luminescent nanocrystalline particles) is preferably 0.05 or higher, 0.07 or higher, 0.1 or higher, 0.13 or higher, or 0.15 or higher, from the viewpoint of further improving the effect of external quantum efficiency. The mass ratio (light-scattering particles / luminescent nanocrystalline particles) is preferably 5.0 or lower, 2.0 or lower, 1.0 or lower, 0.5 or lower, 0.2 or lower, 0.19 or lower, 0.18 or lower, 0.17 or lower, or 0.16 or lower, from the viewpoint of further improving suitability to inkjet processes, optical properties, and their reproducibility.

[0069] From the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink, the total amount of luminescent nanocrystalline particles and light-scattering particles in the ink composition is preferably 15 parts by mass or more, 20 parts by mass or more, or 25 parts by mass or more, per 100 parts by mass of the non-volatile content of the ink composition. From the viewpoint of easily obtaining an appropriate viscosity as an inkjet ink, the total amount of luminescent nanocrystalline particles and light-scattering particles in the ink composition is preferably 60 parts by mass or less, 50 parts by mass or less, or 40 parts by mass or less, per 100 parts by mass of the non-volatile content of the ink composition.

[0070] [Polymer dispersant] The polymeric dispersant is 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. The polymeric dispersant has the function of dispersing light-scattering particles. The polymeric dispersant is adsorbed onto light-scattering particles via the functional group that has affinity for light-scattering particles, and the light-scattering particles are dispersed in the ink composition by electrostatic repulsion and / or steric repulsion between polymeric dispersants. 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). It is preferable that the polymeric dispersant is bound to the surface of the light-scattering particles and adsorbed onto them, but it may also be bound to the surface of the luminescent nanocrystalline particles and adsorbed onto the luminescent nanocrystalline particles, or it may be free in the ink composition.

[0071] 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.

[0072] 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).

[0073] 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.

[0074] 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.

[0075] The polymeric dispersant is preferably a polymer of a single monomer (homopolymer) or a 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 is preferably a comb-shaped or star-shaped graft copolymer. Examples of polymeric dispersants include acrylic resins, polyester resins, polyurethane resins, polyamide resins, polyethers, phenolic resins, silicone resins, polyurea resins, amino resins, epoxy resins, polyamines such as polyethyleneimine and polyallylamine, and polyimides.

[0076] The weight-average molecular weight of the polymeric dispersant is 750 or more, preferably 1000 or more, 1500 or more, 2000 or more, or 3000 or more. For example, the weight-average molecular weight of the polymeric dispersant is preferably 40000 or less, or 30000 or less. When the molecular weight of the polymeric dispersant is within the above range (for example, 1000 or more), the dispersion stability of light-scattering particles is excellent, and the ejection performance of the inkjet ink is further improved. In this specification, the weight-average molecular weight (Mw) is a value measured by gel permeation chromatography (GPC) under the following conditions. Measuring device: HLC-8220GPC, manufactured by Tosoh Corporation. Columns; TSK-GUARDCOLUMN SuperHZ-L (manufactured by Tosoh Corporation) + TSK-GEL SuperHZM-M (manufactured by Tosoh Corporation) x 4 Detector; RI (Differential Refractometer) Data processing; Tosoh Corporation Multi-Station GPC-8020 model II Measurement conditions; Column temperature 40°C Solvent; tetrahydrofuran Flow rate; 0.35ml / min Standard; monodisperse polystyrene Sample: 100 μl of a tetrahydrofuran solution containing 0.2% by mass (based on resin solids content) filtered through a microfilter.

[0077] The polymeric dispersant is preferably a compound having at least a basic functional group. That is, the polymeric dispersant is preferably having an amine value. The amine value of the polymeric dispersant is preferably 0.1 mg KOH / g or more, 1 mg KOH / g or more, 5 mg KOH / g or more, or 10 mg KOH / g or more. The amine value of the polymeric dispersant is preferably 120 mg KOH / g or less, 100 mg KOH / g or less, 90 mg KOH / g or less, or 80 mg KOH / g or less.

[0078] The amine value of a polymer dispersant can be measured as follows: Prepare a sample solution by dissolving x g of polymer dispersant and 1 mL of bromophenol blue reagent in 50 mL of a mixed solution of toluene and ethanol in a volume ratio of 1:1. Titrate the sample solution with 0.5 mol / L hydrochloric acid until it turns green, and calculate the amine value using the following formula. Amine value = y / x × 28.05 In the formula, y represents the volume (mL) of 0.5 mol / L hydrochloric acid required for the titration, and x represents the mass (g) of the polymer dispersant.

[0079] The polymeric dispersant preferably has an acid value, and more preferably has both an acid value and an amine value. The acid value of the polymeric dispersant is preferably, for example, 0 mgKOH / g or more, or 10 mgKOH / g or more, and preferably 70 mgKOH / g or less, 60 mgKOH / g or less, or 50 mgKOH / g or less.

[0080] The acid value can be measured as follows: Prepare a sample solution by dissolving 1 mL of polymer dispersant pg and phenolphthalein reagent in 50 mL of a mixed solution of toluene and ethanol in a volume ratio of 1:1. Titrate the sample solution with a 0.1 mol / L ethanol potassium hydroxide solution (prepared by dissolving 7.0 g of potassium hydroxide in 5.0 mL of distilled water and adding 95 vol% ethanol to make 1000 mL) until the sample solution turns pale pink, and calculate the acid value using the following formula. Acid value=q×r×5.611 / p In the formula, q represents the titration volume (mL) of the 0.1 mol / L ethanol potassium hydroxide solution required for the titration, r represents the titer of the 0.1 mol / L ethanol potassium hydroxide solution required for the titration, and p represents the mass (g) of the polymer dispersant. Examples of polymeric dispersants having the above-mentioned acid value and amine value include dispersants having a linear aliphatic polyester skeleton and an aliphatic polyether skeleton as their basic skeletons and having carboxyl groups and amino groups, copolymers of arylamine moieties with maleic acid and amino group-containing maleic acid, and copolymers of polyarylamine and aliphatic polyester.

[0081] The polymeric dispersant may be used alone or in combination of two or more types. Preferably, the polymeric dispersant contains two or more types of polymeric dispersants.

[0082] Commercially available polymer dispersants can also be used. Examples of commercially available products include the Azisper PB series from Ajinomoto Fine Techno Co., Ltd., the Disperbyk series and BYK- series from BYK, the Efka series from BASF, and Solspers S24000GR from Lubrizol Nippon Co., Ltd.

[0083] The content of the polymer dispersant in the ink composition is 3 to 15 parts by mass per 100 parts by mass of light-scattering particles. The lower limit of the content of the polymer dispersant in the ink composition is preferably 4 parts by mass or more, or 5 parts by mass or more, per 100 parts by mass of light-scattering particles, from the viewpoint of further suppressing the aggregation of components in the ink composition, further improving the effect of suppressing leak light and improving external quantum efficiency, and further improving redispersibility. The upper limit of the content of the polymer dispersant in the ink composition is preferably 13 parts by mass or less, 11 parts by mass or less, 9 parts by mass or less, or 7 parts by mass or less, from the viewpoint of further suppressing the degradation of luminescent nanocrystalline particles and further improving the effect of improving external quantum efficiency. From the above viewpoint, the content of the polymer dispersant in the ink composition is preferably, for example, 3 to 13 parts by mass, 3 to 11 parts by mass, 4 to 9 parts by mass, or 4 to 7 parts by mass per 100 parts by mass of light-scattering particles.

[0084] [Photopolymerizable compound] A photopolymerizable compound is a compound that polymerizes upon irradiation with light. Preferably, the photopolymerizable compound is, for example, a photoradical polymerizable compound. Preferably, the photopolymerizable compound is a photopolymerizable monomer or oligomer. The photopolymerizable compound is used together with a photopolymerization initiator. The photoradical polymerizable compound is used together with a photoradical polymerization initiator. In other words, the ink composition may contain a photopolymerizable component comprising a photopolymerizable compound and a photopolymerization initiator, or it may contain a photoradical polymerizable component comprising a photoradical polymerizable compound and a photoradical polymerization initiator. The ink composition may contain one photopolymerizable compound, two or more, and preferably two or more.

[0085] 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, an ethylenically unsaturated monomer refers to a monomer having an ethylenically unsaturated bond (carbon-carbon double bond).

[0086] The number of ethylenically unsaturated bonds (e.g., the number of ethylenically unsaturated groups) in an ethylenically unsaturated monomer is, for example, 1 to 3. An ethylenically unsaturated monomer may be used alone or in combination with multiple other monomers. From the viewpoint of easily achieving both excellent discharge stability and excellent curability, and from the viewpoint of further improving external quantum efficiency, the photopolymerizable compound may contain monomers having one ethylenically unsaturated group (monofunctional monomers) and monomers having two or more ethylenically unsaturated groups (polyfunctional monomers), and may contain at least one selected from the group consisting of monofunctional monomers and monomers having two ethylenically unsaturated groups (difunctional monomers) and monomers having three ethylenically unsaturated groups (trifunctional monomers).

[0087] The ethylenically unsaturated group is preferably a vinyl group, vinylene group, vinylidene group, (meth)acryloyl group, etc., and more preferably a (meth)acryloyl group. In this specification, "(meth)acryloyl group" means "acryloyl group" and the corresponding "methacryloyl group". The same applies to the expressions "(meth)acrylate" and "(meth)acrylamide".

[0088] The photopolymerizable compound comprises at least one compound having a (meth)acryloyl group as an ethylenically unsaturated group, more preferably at least one selected from the group consisting of (meth)acrylates and (meth)acrylamides, even more preferably at least one (meth)acrylate, and particularly preferably at least one (meth)acrylate having a linear alkyl group having 8 or more carbon atoms. From the viewpoint of easily achieving both excellent discharge stability and excellent curability, and from the viewpoint of further improving external quantum efficiency, the photopolymerizable compound preferably contains two or more types of (meth)acrylates, more preferably a (meth)acrylate having one (meth)acryloyl group (monofunctional (meth)acrylate) and a (meth)acrylate having two or more (meth)acryloyl groups (polyfunctional (meth)acrylate), and even more preferably a monofunctional (meth)acrylate and at least one selected from the group consisting of a (meth)acrylate having two (meth)acryloyl groups (difunctional (meth)acrylate) and a (meth)acrylate having three (meth)acryloyl groups (trifunctional (meth)acrylate). From the viewpoint of further improving optical properties (e.g., wavelength control), the photopolymerizable compound preferably contains a (meth)acrylate having a hydroxyl group.

[0089] Examples of monofunctional monomers include lauryl (meth)acrylate, glycerin mono(meth)acrylate, 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, ethoxydiethylene glycol (meth)acrylate, and methoxytriethylene glycol (meth)acrylate. Butoxydiethylene glycol (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, benzyl (meth)acrylate, phenylbenzyl (meth)acrylate, mono(2-acryloyloxyethyl) succinate, mono(2-methacryloyloxyethyl) succinate, N-[2-(acryloyloxy)ethyl]phthalimide, N-[2-(acryloyloxy)ethyl]tetrahydrophthalimide, 4-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, N,Examples include N-diethylacrylamide, diacetone acrylamide, 4-acryloylmorpholine, N-tert-butylacrylamide, N-hydroxymethylacrylamide, N-hydroxyethylacrylamide, N-tert-octylacrylamide, N-butoxymethylacrylamide, N-phenylacrylamide, and N-dodecylacrylamide.

[0090] Specific 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, 1,9-nonanediol di(meth)acrylate, Tricyclodecanedimethanol di(meth)acrylate, ethylene 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, neopentyl glycol hydroxypivalate diacrylate, tris(2-hydroxyethyl) isocyanurate with two hydroxyl groups (meth)acrylate Di(meth)acrylates substituted with acryloyloxy groups, di(meth)acrylates in which two hydroxyl groups of a diol obtained by adding 4 or more moles of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol are substituted with (meth)acryloyloxy groups, di(meth)acrylates in which two hydroxyl groups of a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A are substituted with (meth)acryloyloxy groups, trimethylolpropane Examples include di(meth)acrylates obtained by adding 3 or more moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A, in which two hydroxyl groups of a triol are substituted with (meth)acryloyloxy groups; 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; N,N'-methylenebisacrylamide; and N,N'-ethylenebisacrylamide.

[0091] Specific examples of monomers having three ethylenically unsaturated groups (trifunctional monomers) include glycerin tri(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and EO-modified trimethylolpropane tri(meth)acrylate.

[0092] From the viewpoint of easily obtaining pixel portions (cured products of the ink composition) with excellent reliability, the photopolymerizable compound is preferably alkali-insoluble. In this specification, alkali-insoluble photopolymerizable compound means that the amount of photopolymerizable compound dissolved 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 above amount of dissolution of the photopolymerizable compound is preferably 10% by mass or less, and more preferably 3% by mass or less.

[0093] From the viewpoint of easily obtaining an appropriate viscosity for inkjet ink, having good curability of the ink composition, and improving the solvent resistance and abrasion resistance of the pixel portion (cured product of the ink composition), the content of the photopolymerizable compound is preferably 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more per 100 parts by mass of the nonvolatile content of the ink composition. From the viewpoint of easily obtaining an appropriate viscosity for inkjet ink and obtaining better optical properties (e.g., external quantum efficiency), the content of the photopolymerizable compound is preferably 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, or 20 parts by mass or less per 100 parts by mass of the nonvolatile content of the ink composition.

[0094] In the ink composition of this embodiment, the photopolymerizable compound also functions as a dispersion medium, making it possible to disperse light-scattering particles and luminescent nanocrystalline particles without solvents. In this case, there is the advantage that the step of removing the solvent by drying when forming the pixel portion is unnecessary.

[0095] [Photopolymerization initiator] The ink composition may further contain a photopolymerization initiator. The photopolymerization initiator is used together with a photopolymerizable compound. The photopolymerization initiator is, for example, a photoradical polymerization initiator or a photocationic polymerization initiator. As a photoradical polymerization initiator, a molecular cleavage type or a hydrogen abstraction type photoradical polymerization initiator is preferred.

[0096] Suitable molecular cleavage-type photoradical polymerization initiators include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide. Other molecular cleavage-type photoradical polymerization initiators that may be used in combination include 1-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.

[0097] Examples of hydrogen abstraction-type photoradical polymerization initiators include benzophenone, 4-phenylbenzophenone, isophthalphenone, and 4-benzoyl-4'-methyl-diphenyl sulfide. A combination of a molecular cleavage-type photoradical polymerization initiator and a hydrogen abstraction-type photoradical polymerization initiator may also be used.

[0098] Commercially available photocationic polymerization initiators can also be used. Examples of commercially available products include sulfonium salt-based photocationic polymerization initiators such as "CPI-100P" from Sunapro, acylphosphine oxide compounds such as "Lucirin TPO" from BASF, and "Irgacure 907," "Irgacure 819," "Irgacure 379EG," "Irgacure 184," and "Irgacure PAG290" from BASF.

[0099] From the viewpoint of the curability of the ink composition, the content of the photopolymerization initiator is preferably 0.1 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, 3 parts by mass or more, or 5 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, 30 parts by mass or less, 20 parts by mass or less, or 10 parts by mass or less per 100 parts by mass of the photopolymerizable compound.

[0100] The ink composition may further contain components other than those described above (for example, organic solvents, thermosetting resins, curing agents, curing accelerators (curing catalysts), polymerization inhibitors, chain transfer agents, antioxidants, etc.) to the extent that they do not impair the effects of the present invention.

[0101] The viscosity of the ink composition described above at the ink temperature during inkjet printing is preferably 2 mPa·s or more, 5 mPa·s or more, or 7 mPa·s or more, from the viewpoint of ejection stability during inkjet printing. The viscosity of the ink composition at the ink temperature during inkjet printing is preferably 20 mPa·s or less, 15 mPa·s or less, or 12 mPa·s or less. In this specification, the viscosity of the ink composition refers to the viscosity measured by, for example, an E-type viscometer, measured at 25°C.

[0102] When the viscosity of the ink composition at the ink temperature during inkjet printing is 2 mPa·s or higher, the meniscus shape of the inkjet ink at the tip of the ink ejection hole of the ejection head is stable, making it easier to control the ejection of the inkjet ink (for example, controlling the ejection amount and timing). On the other hand, when the viscosity of the ink composition at the ink temperature during inkjet printing is 20 mPa·s or lower, the inkjet ink can be smoothly ejected from the ink ejection hole.

[0103] The surface tension of the ink composition is preferably suitable for an inkjet system, specifically in the range of 20 to 40 mN / m, and more preferably in the range of 25 to 35 mN / m. Setting the surface tension within this range facilitates ejection control (e.g., control of ejection volume and ejection timing) and suppresses the occurrence of flight deviation. Flight deviation refers to a deviation of 30 μm or more from the target position when the ink composition is ejected from the ink ejection hole. When the surface tension is 40 mN / m or less, the meniscus shape at the tip of the ink ejection hole is stable, making it easier to control the ejection of the ink composition (e.g., control of ejection volume and ejection timing). On the other hand, when the surface tension is 20 mN / m or more, contamination of the area around the ink ejection hole with inkjet ink can be prevented, thus suppressing the occurrence of flight deviation. In other words, the ink composition will not land accurately on the pixel area where it is to land, resulting in insufficient filling of some pixels, nor will it land on a pixel area (or pixel area) adjacent to the area where it is to land, thus preventing a decrease in color reproducibility. The surface tension described in this specification refers to the surface tension measured at 23°C and measured using the ring method (also known as the ring-to-ring method).

[0104] The ink composition of this embodiment is preferably applied to a piezojet type inkjet recording device that uses a mechanical ejection mechanism with a piezoelectric element. In the piezojet method, the ink composition is not exposed to high temperatures instantaneously during ejection. Therefore, deterioration of the luminescent nanocrystalline particles is less likely to occur, and the expected luminescence characteristics can be more easily obtained in the pixel area (light conversion layer).

[0105] <Method for manufacturing ink composition> The ink composition of the above-described embodiment includes, for example, a step of mixing the components of the ink composition described above. The method for manufacturing the ink composition may further include a step of dispersing the mixture of the components.

[0106] A method for producing an ink composition includes, for example, a step of mixing a dispersion of light-scattering particles containing light-scattering particles and a polymer dispersant with a dispersion of luminescent nanocrystalline particles containing luminescent nanocrystalline particles and an organic ligand. This method makes it possible to improve the optical properties of the pixel area (improvement of external quantum efficiency, suppression of leaked light, etc.) and to obtain an ink composition with excellent redispersibility.

[0107] A method for producing an ink composition may include a step of preparing a dispersion of light-scattering particles containing light-scattering particles, a polymeric dispersant, and a photopolymerizable compound, prior to the step of mixing a dispersion of light-scattering particles and a dispersion of luminescent nanocrystalline particles. In the step of preparing the dispersion of light-scattering particles, the dispersion of light-scattering particles may be prepared by mixing the light-scattering particles, the polymeric dispersant, and the photopolymerizable compound and performing a dispersion treatment. The mixing and dispersion treatment may be carried out using dispersion equipment such as a bead mill, paint conditioner, planetary agitator, or jet mill. From the viewpoint of achieving good dispersibility of the 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.

[0108] The method for producing the ink composition may further include a step of preparing a dispersion of luminescent nanocrystalline particles containing luminescent nanocrystalline particles, an organic ligand, and a photopolymerizable compound, prior to the step of mixing a dispersion of light-scattering particles and a dispersion of luminescent nanocrystalline particles. In the step of preparing the dispersion of luminescent nanocrystalline particles, the dispersion of luminescent nanocrystalline particles may be prepared by mixing the luminescent nanocrystalline particles, the photopolymerizable compound, and the organic ligand and performing a dispersion treatment. The mixing and dispersion treatment may be carried out using conventional stirring devices such as electromagnetic stirrers and three-way motors, or dispersion devices such as vortex mixers, bead mills, paint conditioners, planetary stirrers, and jet mills. From the viewpoint of not imparting excessive energy to the luminescent nanocrystalline particles, it is preferable to use conventional stirring devices such as electromagnetic stirrers and three-way motors or vortex mixers. According to this method, the luminescent nanocrystalline particles can be sufficiently dispersed without degrading their performance. Therefore, it is possible to improve the optical properties of the pixel area (such as improving external quantum efficiency and suppressing stray light), and to obtain an ink composition with excellent redispersibility.

[0109] <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 nanocrystalline particles (non-luminescent ink composition). The non-luminescent ink composition is, for example, a curable ink composition. The non-luminescent ink composition may be a conventionally known ink composition and may have the same composition as the ink composition of the embodiment described above (luminescent ink composition), except that it does not contain luminescent nanocrystalline particles.

[0110] Since non-luminescent ink compositions do not contain luminescent nanocrystalline particles, when light is incident on a pixel portion formed by a non-luminescent ink composition (a pixel portion including 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-luminescent ink compositions are suitably used to form pixel portions of the same color as the light from a light source. For example, if the light from the light source has a wavelength in the range of 420 to 480 nm (blue light), the pixel portion formed by the non-luminescent ink composition can become a blue pixel portion.

[0111] 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 the light incident on the pixel portion, thereby reducing the difference in light intensity of the light emitted from the pixel portion at the viewing angle.

[0112] <Photon conversion layer and color filter> The details of the light conversion layer and color filter obtained using the ink composition set of the above-described embodiment will be explained below 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.

[0113] Figure 1 is a schematic cross-sectional view of a color filter according to one embodiment. As shown in Figure 1, the color filter 100 comprises a substrate 40 and a light conversion layer 30 provided on the substrate 40. The light conversion layer 30 comprises a plurality of pixel portions 10 and a light-shielding portion 20.

[0114] The light conversion layer 30 has a pixel section 10 comprising 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, repeating in this order. The light-shielding sections 20 are provided between adjacent pixel sections, that is, between the first pixel section 10a and the second pixel section 10b, between the second pixel section 10b and the third pixel section 10c, and between the third pixel section 10c and the first pixel section 10a. In other words, these adjacent pixel sections are separated by the light-shielding sections 20.

[0115] The first pixel portion 10a and the second pixel portion 10b are luminescent pixel portions (luminescent pixel portions) each containing a cured product of the ink composition of the embodiment described above. The first pixel portion 10a includes a first curing component 13a and first luminescent nanocrystalline particles 11a and first light-scattering particles 12a dispersed in the first curing component 13a, respectively. Similarly, the second pixel portion 10b includes a second curing component 13b and second luminescent nanocrystalline particles 11b and second light-scattering particles 12b dispersed in the second curing component 13b, respectively. The curing component is a component obtained by polymerization of a photopolymerizable compound and includes a polymer of the photopolymerizable compound, an organic ligand, and a polymeric dispersant. The curing component may further contain organic components (such as unreacted photopolymerizable compounds) that were included in the ink composition. In the first pixel portion 10a and the second pixel portion 10b, the first curing component 13a and the second curing component 13b may be the same or different, and the first light-scattering particle 12a and the second light-scattering particle 12b may be the same or different.

[0116] The first luminescent nanocrystalline particle 11a is a red-emitting nanocrystalline particle that absorbs light with wavelengths in the range of 420 to 480 nm and emits light with an emission peak wavelength in the range of 605 to 665 nm. In other words, the first pixel portion 10a can be described as a red pixel portion for converting blue light to red light. The second luminescent nanocrystalline particle 11b is a green-emitting nanocrystalline particle that absorbs light with wavelengths in the range of 420 to 480 nm and emits light with an emission peak wavelength in the range of 500 to 560 nm. In other words, the second pixel portion 10b can be described as a green pixel portion for converting blue light to green light.

[0117] The content of luminescent nanocrystalline particles in the luminescent pixel portion is preferably 15% by mass or more, 18% by mass or more, 20% by mass or more, or 24% by mass or more, based on the total mass of the cured product of the luminescent ink composition, from the viewpoint of superior effect in improving external quantum efficiency and obtaining excellent luminescence intensity. The content of luminescent nanocrystalline particles is preferably 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, or 40% by mass or less, based on the total mass of the cured product of the luminescent ink composition, from the viewpoint of superior reliability of the pixel portion and obtaining excellent luminescence intensity.

[0118] From the viewpoint of superior improvement in external quantum efficiency, the content of light-scattering particles in the luminescent pixel portion is preferably, for example, 0.1% by mass or more, and more preferably 1% by mass or more, or 2% 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 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less, based on the total mass of the cured product of the luminescent ink composition.

[0119] 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 nanocrystalline particles, but contains light-scattering particles and a curing component. That is, the third pixel portion 10c contains 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 polymerizable compound, and includes a polymer of a polymerizable compound. The third light-scattering particles 12c may be the same as or different from the first light-scattering particles 12a and the second light-scattering particles 12b.

[0120] The third pixel portion 10c has a transmittance of 30% or more for light with wavelengths in the range of 420 to 480 nm, for example. Therefore, the third pixel portion 10c functions as a blue pixel portion when a light source emitting light with wavelengths in the range of 420 to 480 nm is used. The transmittance of the third pixel portion 10c can be measured using a microspectroscopic device.

[0121] From the viewpoint of further reducing the difference in light intensity at the viewing angle, the content of light-scattering particles in the non-emissive pixel portion is preferably 1% by mass or more, 5% by mass or more, or 10% 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 50% by mass or less, 30% by mass or less, or 20% by mass or less, based on the total mass of the cured product of the non-emissive ink composition.

[0122] The thickness of the pixel portion (first pixel portion 10a, second pixel portion 10b, and third pixel portion 10c) is preferably, for example, 1 μm or more, 2 μm or more, or 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, for example, 30 μm or less, 20 μm or less, or 15 μm or less.

[0123] The light-shielding portion 20 is a so-called black matrix provided for the purpose of separating adjacent pixels to prevent color mixing and preventing light leakage from the light source. The material constituting the light-shielding portion 20 is not particularly limited, and in addition to metals such as chromium, cured resin compositions containing light-shielding particles such as carbon nanoparticles, metal oxides, inorganic pigments, and organic pigments in a binder polymer can be used. As the binder polymer used here, one or more resins such as polyimide resin, acrylic resin, epoxy resin, polyacrylamide, polyvinyl alcohol, gelatin, casein, and cellulose can be mixed, or a photosensitive resin or an O / W emulsion type resin composition (for example, an emulsion of reactive silicone) can be used. The thickness of the light-shielding portion 20 is preferably, for example, 0.5 μm or more, or 10 μm or less.

[0124] The substrate 40 is a transparent substrate with light transmittance, and can be a transparent glass substrate such as quartz glass, Pyrex® glass, or synthetic quartz plate, or a transparent flexible substrate such as a transparent resin film or optical resin film. Among these, it is preferable to use a glass substrate made of alkali-free glass that does not contain alkali components in the glass. Specifically, Corning's "7059 glass," "1737 glass," "Eagle 200," and "Eagle XG," Asahi Glass's "AN100," and Nippon Electric Glass's "OA-10G" and "OA-11" are suitable. These are materials with a low coefficient of thermal expansion and excellent dimensional stability and workability in high-temperature heat treatment.

[0125] The color filter 100, which includes the above-described light conversion layer 30, is preferably used when a light source that emits light with a wavelength in the range of 420 to 480 nm is used.

[0126] 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 regions demarcated by the light-shielding portions 20 on the substrate 40. The pixel portions 10 can be formed by a method comprising the steps of selectively adhering an ink composition to the pixel portion formation regions on the substrate 40 using an inkjet method, and curing the ink composition to obtain luminescent pixel portions. By using the above-mentioned luminescent ink composition as the ink composition, luminescent pixel portions can be obtained, and by using a non-luminescent ink composition, non-luminescent pixel portions can be obtained.

[0127] Methods for forming the light-shielding portion 20 include forming a thin film of a metal such as chromium, or a thin film of a resin composition containing light-shielding particles, in the region that forms the boundary between multiple pixel portions on one side of the substrate 40, and then patterning this thin film. The metal thin film can be formed, for example, by sputtering or vacuum deposition, and the thin film of a resin composition containing light-shielding particles can be formed, for example, by coating or printing. Photolithography can be used as a method for patterning.

[0128] 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.

[0129] The ink composition may be cured by irradiation with active energy rays (e.g., ultraviolet light). For example, a mercury lamp, metal halide lamp, xenon lamp, or LED may be used for curing. The wavelength of the irradiated light is preferably, for example, 200 nm or more, or 440 nm or less. The exposure dose is, for example, 10 mJ / cm². 2 Above 20,000 mJ / cm², or 20,000 mJ / cm². 2 The following is preferable:

[0130] Although an embodiment of a color filter, a light conversion layer, and a method for manufacturing them has been described above, the present invention is not limited to the above embodiment.

[0131] For example, the light conversion layer may include a pixel portion (blue pixel portion) containing a cured product of a luminescent ink composition containing blue-emitting nanocrystalline particles, instead of or in addition to the third pixel portion 10c. Alternatively, the light conversion layer may include a pixel portion (e.g., yellow pixel portion) containing a cured product of a luminescent ink composition containing nanocrystalline particles that emit light of a color other than red, green, or blue. In these cases, it is preferable that each of the luminescent nanocrystalline particles contained in each pixel portion of the light conversion layer has an absorption maximum wavelength in the same wavelength range.

[0132] Furthermore, at least a portion of the pixel portion of the light conversion layer may contain a cured product of a composition containing pigments other than luminescent nanocrystalline particles.

[0133] Furthermore, the color filter may have an ink-repellent layer made of an ink-repellent material that is narrower than the light-shielding area, on the pattern of the light-shielding area. Alternatively, instead of providing an ink-repellent layer, a photocatalyst-containing layer may be formed in a solid coating manner as a wettability variable layer in the area including the pixel area formation area, and then the photocatalyst-containing layer may be exposed by irradiating it with light through a photomask to selectively increase the ink-hydration of the pixel area formation area. Examples of photocatalysts include titanium dioxide and zinc oxide.

[0134] Furthermore, the color filter may include an ink-receiving layer containing hydroxypropyl cellulose, polyvinyl alcohol, gelatin, etc., between the substrate and the pixel portion.

[0135] Furthermore, the color filter may have a protective layer on the pixel portion. This protective layer is provided to flatten the color filter and to prevent the elution of components contained in the pixel portion, or components contained in the pixel portion and the photocatalyst-containing layer, into the liquid crystal layer. The material constituting the protective layer can be one that is known to be used as a protective layer for color filters.

[0136] Furthermore, in addition to the luminescent nanocrystalline particles described above, the pixel portion of the light conversion layer in this embodiment may also contain a pigment of approximately the same color as the luminescent color of the luminescent nanocrystalline particles. To include the pigment in the pixel portion, the ink composition may also contain the pigment.

[0137] Furthermore, in this embodiment, one or two of the red pixel portion (R), green pixel portion (G), and blue pixel portion (B) in the light conversion layer may be pixel portions containing a colorant without containing light-emitting nanocrystalline particles. Known colorants can be used as colorants, for example, diketopyrrolopyrrole pigments and / or anionic red organic dyes can be used as colorants for the red pixel portion (R). At least one colorant selected from the group consisting of copper halide phthalocyanine pigment, phthalocyanine green dye, and a mixture of phthalocyanine blue dye and azo yellow organic dye can be used for the green pixel portion (B). ε-type copper phthalocyanine pigment and / or cationic blue organic dye can be used as colorants for the blue pixel portion (B). When these colorants are included in the light conversion layer, 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) from the viewpoint of preventing a decrease in transmittance.

[0138] Furthermore, the color filter may include a conventional color filter layer between the substrate and the pixel portion of this embodiment, which does not contain luminescent nanocrystalline particles but contains the above-mentioned colorant. In other words, the color filter of this embodiment may comprise a substrate, a color filter layer provided on the substrate which does not contain luminescent nanocrystalline particles but contains a colorant, and a pixel portion of this embodiment provided on the color filter layer. [Examples]

[0139] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited only to the following examples. All the materials used in the examples were those in which argon gas was introduced to replace dissolved oxygen with argon gas. The liquid materials used in the examples were dehydrated with molecular sieves 3A for 48 hours or more in advance before mixing and then used.

[0140] <Preparation of Photopolymerizable Compound> The photopolymerizable compounds shown in Table 1 were prepared.

Table 1

[0141] Example 1 <Preparation of QD Powder A> [Synthesis of Organic Ligand 1] After polyethylene glycol |average Mn 350| (manufactured by Sigma-Aldrich) was put into a flask, an equimolar amount of succinic anhydride (manufactured by Sigma-Aldrich) was added thereto while stirring in a nitrogen gas environment. The internal temperature of the flask was raised to 80 °C and stirred for 8 hours to obtain organic ligand 1 represented by the following formula (A) as a pale yellow viscous oil.

Chemical Formula

[0142] [Preparation of QD Powder A by Ligand Exchange] To an InP nanocrystalline dispersion manufactured by Nanosys (InP QD in Heptane Red InP QD, QD particle (luminescent nanocrystalline particle) concentration 30%, organic ligand: oleic acid), 2.0 times the amount of PGMEA and 35% by mass of organic ligand 1 relative to the amount of QD particles (excluding the amount of organic ligand) were added, and ligand exchange was performed by stirring at 80°C for 1 hour. To this solution, 4 times the amount of heptane was added to agglomerate the QD particles, which were then precipitated by centrifugation, and the QD particles were separated by sedation of the supernatant. The obtained QD particles were dried in a vacuum dryer to obtain red luminescent QD powder A (QD particles / organic ligand = 76% by mass / 24% by mass).

[0143] <Preparation of light-scattering particle dispersion A> In a container filled with argon gas, 8.0 g of titanium dioxide (product name: PF-690, manufactured by Ishihara Sangyo Co., Ltd., average particle size (volume average diameter): 210 nm), 0.4 g of polymer dispersant (product name: PB-821, manufactured by Ajinomoto Fine Techno Co., Ltd.), and 11.6 g of phenoxyethyl acrylate (product name: Light Acrylate PO-A, manufactured by Kyoeisha Chemical Co., Ltd.) were mixed. Then, zirconia beads (diameter: 0.03 mm) were added to the resulting mixture, and the mixture was dispersed by shaking with paint conditioner for 4 hours. Next, the zirconia beads were removed from the mixture using a polyester mesh filter to obtain a light-scattering particle dispersion.

[0144] <Preparation of the ink composition of Example 1> 1.71 g of QD powder A, 0.52 g of light-scattering particle dispersion A, 0.30 g of photopolymerization initiator (phenyl (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by IGM resin, product name: Omnirad TPO)), 2.37 g of a mixture of photopolymerizable compounds (PhEM:LM:HDMMA = 43:22:35 (mass ratio)), and 0.05 g of hindered phenol antioxidant (manufactured by BASF Japan, product name: Irganox1010) were combined and uniformly mixed in a container filled with argon gas. The mixture was then filtered in a glove box using a filter with a pore size of 5 μm. Furthermore, argon gas was introduced into the container containing the obtained filtrate to saturate the container with argon gas. Next, the argon gas was removed by reducing the pressure to obtain the ink composition of Example 1.

[0145] Example 2 <Preparation of QD powder B by ligand exchange> To an InP nanocrystalline dispersion manufactured by Nanosys (InP QD in Heptane Green InP QD, QD particle (luminescent nanocrystalline particle) concentration 30%, organic ligand: oleic acid), 2.0 times the amount of PGMEA and 40% by mass of organic ligand 1 relative to the amount of QD particles (excluding the amount of organic ligand) were added, and ligand exchange was performed by stirring at 80°C for 1 hour. To this solution, 4 times the amount of heptane was added to agglomerate the QD particles, which were then precipitated by centrifugation, and the QD particles were separated by sedation of the supernatant. The obtained QD particles were dried in a vacuum dryer to obtain green luminescent QD powder B (QD particles / organic ligand = 66% by mass / 34% by mass).

[0146] <Preparation of the ink composition of Example 2> 1.71 g of QD powder B, 0.59 g of light-scattering particle dispersion A, 0.12 g of photopolymerization initiator (phenyl (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by IGM resin, product name: Omnirad TPO)), 2.39 g of a mixture of photopolymerizable compounds (PhEM:LA:HDMMA = 39:23:38 (mass ratio)), and 0.05 g of hindered phenol antioxidant (manufactured by BASF Japan, product name: Irganox1010) were combined and uniformly mixed in a container filled with argon gas. The mixture was then filtered in a glove box using a filter with a pore size of 5 μm. Furthermore, argon gas was introduced into the container containing the obtained filtrate to saturate the container with argon gas. Next, the argon gas was removed by reducing the pressure to obtain the ink composition of Example 2.

[0147] Example 3 <Preparation of light-scattering particle dispersion B> In a container filled with argon gas, 8.0 g of titanium dioxide (product name: PF-690, manufactured by Ishihara Sangyo Co., Ltd., average particle size (volume average diameter): 210 nm), 0.8 g of polymer dispersant (product name: PB-821, manufactured by Ajinomoto Fine Techno Co., Ltd.), and 11.2 g of phenoxyethyl acrylate (product name: Light Acrylate PO-A, manufactured by Kyoeisha Chemical Co., Ltd.) were mixed. Then, zirconia beads (diameter: 0.03 mm) were added to the resulting mixture, and the mixture was dispersed by shaking with paint conditioner for 4 hours. Next, the zirconia beads were removed from the mixture using a polyester mesh filter to obtain a light-scattering particle dispersion.

[0148] <Preparation of the ink composition of Example 3> The ink composition of Example 3 was prepared in the same manner as in Example 2, except that light-scattering particle dispersion B was used instead of light-scattering particle dispersion A, and GLM was added to the mixture of photopolymerizable compounds, changing the weight ratio PhEM:LA:HDDMA:GLM = 34:22:38:6.

[0149] Example 4 <Preparation of light-scattering particle dispersion C> In a container filled with argon gas, 8.0 g of titanium dioxide (product name: PF-690, manufactured by Ishihara Sangyo Co., Ltd., average particle size (volume average diameter): 210 nm), 0.4 g of polymer dispersant (product name: PB-821, manufactured by Ajinomoto Fine Techno Co., Ltd., amine value: 10, acid value: 17), 0.4 g of polymer dispersant (product name: Solspers S24000GR, manufactured by Nippon Lubrizol Co., Ltd., amine value: 42, acid value: 26), and 11.2 g of phenoxyethyl acrylate (product name: Light Acrylate PO-A, manufactured by Kyoeisha Chemical Co., Ltd.) were mixed. Then, zirconia beads (diameter: 0.03 mm) were added to the resulting mixture, and the mixture was dispersed by shaking with paint conditioner for 4 hours. Next, the zirconia beads were removed from the mixture using a polyester mesh filter to obtain a light-scattering particle dispersion.

[0150] <Preparation of the ink composition of Example 4> The ink composition of Example 4 was prepared in the same manner as in Example 3, except that light-scattering particle dispersion C was used instead of light-scattering particle dispersion B.

[0151] Comparative Example 1 <Preparation of light-scattering particle dispersion D> In a container filled with argon gas, 8.0 g of titanium dioxide (product name: PF-690, manufactured by Ishihara Sangyo Co., Ltd., average particle size (volume average diameter): 210 nm), 0.16 g of polymer dispersant (product name: PB-821, manufactured by Ajinomoto Fine Techno Co., Ltd.), and 11.8 g of phenoxyethyl acrylate (product name: Light Acrylate PO-A, manufactured by Kyoeisha Chemical Co., Ltd.) were mixed. Then, zirconia beads (diameter: 0.03 mm) were added to the resulting mixture, and the mixture was dispersed by shaking with paint conditioner for 4 hours. Next, the zirconia beads were removed from the mixture using a polyester mesh filter to obtain a light-scattering particle dispersion.

[0152] <Preparation of the ink composition of Comparative Example 1> The ink composition of Comparative Example 1 was prepared in the same manner as in Example 1, except that light-scattering particle dispersion D was used instead of light-scattering particle dispersion A.

[0153] Comparative Example 2 <Preparation of QD powder C by ligand exchange> To an InP nanocrystalline dispersion manufactured by Nanosys (InP QD in Heptane Red InP QD, QD particle (luminescent nanocrystalline particle) concentration 30%, organic ligand: oleic acid), 2.0 times the amount of PGMEA and 20% by mass of organic ligand 1 relative to the amount of QD particles (excluding the amount of organic ligand) were added, and ligand exchange was performed by stirring at 80°C for 1 hour. To this solution, 4 times the amount of heptane was added to agglomerate the QD particles, which were then precipitated by centrifugation, and the QD particles were separated by sedation of the supernatant. The obtained QD particles were dried in a vacuum dryer to obtain red luminescent QD powder C (QD particles / organic ligand = 86% by mass / 14% by mass).

[0154] <Preparation of the ink composition of Comparative Example 2> The ink composition of Comparative Example 1 was prepared in the same manner as in Example 1, except that QD powder C was used instead of QD powder A.

[0155] Comparative Example 3 <Preparation of light-scattering particle dispersion E> In a container filled with argon gas, 8.0 g of titanium dioxide (product name: PF-690, manufactured by Ishihara Sangyo Co., Ltd., average particle size (volume average diameter): 210 nm), 1.44 g of polymer dispersant (product name: PB-821, manufactured by Ajinomoto Fine Techno Co., Ltd.), and 10.6 g of phenoxyethyl acrylate (product name: Light Acrylate PO-A, manufactured by Kyoeisha Chemical Co., Ltd.) were mixed. Then, zirconia beads (diameter: 0.03 mm) were added to the resulting mixture, and the mixture was dispersed by shaking with paint conditioner for 4 hours. Next, the zirconia beads were removed from the mixture using a polyester mesh filter to obtain a light-scattering particle dispersion.

[0156] <Preparation of the ink composition of Comparative Example 3> The ink composition of Comparative Example 3 was prepared in the same manner as in Example 1, except that light-scattering particle dispersion E was used instead of light-scattering particle dispersion A.

[0157] Comparative Example 4 <Preparation of QD powder D by ligand exchange> To an InP nanocrystalline dispersion manufactured by Nanosys (InP QD in Heptane Red InP QD, QD particle (luminescent nanocrystalline particle) concentration 30%, organic ligand: oleic acid), 2.0 times the amount of PGMEA and 60% by mass of organic ligand 1 relative to the amount of QD particles (excluding the amount of organic ligand) were added, and ligand exchange was performed by stirring at 80°C for 1 hour. To this solution, 4 times the amount of heptane was added to agglomerate the QD particles, which were then precipitated by centrifugation, and the QD particles were separated by sedation of the supernatant. The obtained QD particles were dried in a vacuum dryer to obtain red luminescent QD powder D (QD particles / organic ligand = 48% by mass / 52% by mass).

[0158] <Preparation of the ink composition of Comparative Example 4> The ink composition of Comparative Example 4 was prepared in the same manner as in Example 1, except that luminescent nanocrystalline particle dispersion D was used instead of luminescent nanocrystalline particle dispersion A.

[0159] Preparation of evaluation samples The ink composition was applied to a glass substrate using a spin coater in air to a film thickness of 10 μm. The coated film was cured by irradiating it with UV light in a nitrogen atmosphere using an LED lamp with a main wavelength of 395 nm to an integrated light intensity of 10,000 mJ / cm2. Then, it was heated at 180°C for 30 minutes in a glove box with an oxygen concentration of 1 volume% or less to form a layer (photoconversion layer) consisting of the cured ink composition on the glass substrate. This obtained a sample for evaluation.

[0160] Evaluation of external quantum efficiency (EQE) A blue LED (peak emission wavelength: 450 nm) manufactured by CCS Corporation was used as the surface-emitting light source. The measurement device consisted of an integrating sphere connected to a radiation spectrophotometer (product name "MCPD-9800") manufactured by Otsuka Electronics Co., Ltd., with the integrating sphere placed above the blue LED. The prepared evaluation sample was inserted between the blue LED and the integrating sphere, and the spectrum observed and the illuminance at each wavelength were measured with the blue LED lit. The external quantum efficiency was determined from the spectrum and illuminance measured by the above measuring device as follows. The external quantum efficiency is a value that indicates what proportion of the light (photons) incident on the photoconversion layer is emitted to the observer as fluorescence. Therefore, a larger value indicates that the photoconversion layer has excellent emission characteristics and is an important evaluation indicator. Red QD EQE(%)=[P1(Red)] / E(Blue)×100 Green QD EQE(%)=[P1(Green) / E(Blue)]×100 Here, E (Blue), P1 (Red), and P1 (Green) represent the following, respectively. E (Blue): Represents the sum of "illuminance × wavelength ÷ hc" in the wavelength range of 380~490nm. P1 (Red): Represents the sum of "illuminance × wavelength ÷ hc" in the wavelength range of 590~780nm. P1 (Green): Sum of "illuminance × wavelength ÷ hc" in the wavelength range of 500~650nm. Represents a value. These values ​​correspond to the number of photons observed. Note that h represents Planck's constant and c represents the speed of light.

[0161] EQE was evaluated based on the following criteria. A: RedQD EQE≧35%, GreenQD EQE≧30% B:RedQD30% <EQE<35%、GreenQD25%<EQE<30% C: RedQD EQE≦30%, GreenQD EQE≦25%

[0162] Evaluation of redispersibility (filtration) When luminescent nanocrystalline particles and light-scattering particles aggregate, their redispersibility deteriorates, which can lead to poor ejection performance as an inkjet ink. Therefore, to evaluate the redispersibility of the particles, the filterability of the ink composition was evaluated. Since aggregates reduce filterability, better filterability indicates better redispersibility. 5 ml of the ink composition, stored in a 40°C constant temperature bath for two weeks, was stirred in a vortex mixer and then filtered using a φ25 mm polypropylene filter with a pore size of 1.2 μm (manufactured by Nippon Pall Co., Ltd.) at a pressure of 0.1 MPa. Samples that were completely filtered in 2 minutes were designated as "A", samples that were completely filtered in 10 minutes were designated as "B", and samples that could not be completely filtered were designated as "C".

[0163] Evaluation of light leakage A blue LED (peak emission wavelength: 450 nm) manufactured by CCS Corporation was used as a surface-emitting light source. The evaluation sample was placed on this light source with the glass substrate side facing downwards. An integrating sphere was connected to an luminescence spectrophotometer (product name "MCPD-9800") manufactured by Otsuka Electronics Co., Ltd., and the integrating sphere was placed close to the light conversion filter placed on the blue LED. In this state, the blue LED was turned on, and the peak intensity (S) of the observed light at a wavelength of 450 nm was measured. Next, the light at a wavelength of 450 nm was observed in the same manner as above, except that the glass substrate (slide glass) used to fabricate the light conversion filter was placed on the light source instead of the light conversion filter, and the peak intensity (R) of the light was measured. The leakage rate T (peak intensity ratio: S / R × 100) of the light at a wavelength of 450 nm was calculated and evaluated according to the following criteria. A smaller light leakage rate indicates higher color purity, which is preferable. A: Red QD T≦10%, Green QD T≦20% C: Red QD T>10%, Green QD T>20%

[0164] Tables 2 and 3 show the evaluation results. The amount of organic ligand for luminescent nanocrystalline particles in the table refers to the content of organic ligand per 100 parts by mass of luminescent nanocrystalline particles in the ink composition. The amount of dispersant for light-scattering particles in the table refers to the content of polymeric dispersant per 100 parts by mass of light-scattering particles in the ink composition.

[0165] [Table 2] [Table 3]

[0166] The ink composition of the example was shown to improve the external quantum efficiency of the coating film and also exhibit excellent redispersibility (compared to the comparative example). It was also confirmed that the ink composition of the example further has a light leakage suppression effect. [Explanation of symbols]

[0167] 10...Pixel section, 10a...First pixel section, 10b...Second pixel section, 10c...Third pixel section, 11a...First luminescent nanocrystalline particle, 11b...Second luminescent nanocrystalline particle, 12a...First light-scattering particle, 12b...Second light-scattering particle, 12c...Third light-scattering particle, 20...Light-shielding section, 30...Light conversion layer, 40...Substrate, 100...Color filter.

Claims

1. A material comprising: luminescent nanocrystalline particles containing InP; an organic ligand capable of binding to the surface of the luminescent nanocrystalline particles; light-scattering particles; a polymeric dispersant; and a photopolymerizable compound. The aforementioned organic ligand is of the following formula (A) 【Chemistry 1】 The organic ligand shown is, The content of the organic ligand is 15 to 40 parts by mass per 100 parts by mass of the luminescent nanocrystalline particles. An inkjet ink composition for color filters, wherein the amount of the polymer dispersant is 3 to 15 parts by mass per 100 parts by mass of the light-scattering particles.

2. The inkjet ink composition for color filters according to claim 1, wherein the molecular weight of the organic ligand is 1000 or less.

3. The inkjet ink composition for color filters according to claim 1 or 2, wherein the weight-average molecular weight of the polymer dispersant is 1000 or more.

4. The inkjet ink composition for color filters according to any one of claims 1 to 3, wherein the polymer dispersant has both an acid value and an amine value.

5. The inkjet ink composition for color filters according to any one of claims 1 to 3, wherein the polymer dispersant comprises two or more polymer dispersants.

6. The inkjet ink composition for color filters according to any one of claims 1 to 5, wherein the average particle size of the light-scattering particles is 0.15 μm or more and 0.5 μm or less.

7. A cured product of an inkjet ink composition for color filters according to any one of claims 1 to 6.

8. It comprises a plurality of pixel portions and a light-shielding portion provided between the plurality of pixel portions, The photoconversion layer has a plurality of pixel portions, each having a light-emitting pixel portion containing a cured product of the inkjet ink composition for color filters described in any one of claims 1 to 6.

9. As the light-emitting pixel portion, A first luminescent pixel portion containing luminescent nanocrystalline particles that absorb light with wavelengths in the range of 420 to 480 nm and emit light having an emission peak wavelength in the range of 605 to 665 nm, A second luminescent pixel portion containing luminescent nanocrystalline particles that absorb light with wavelengths in the range of 420 to 480 nm and emit light having an emission peak wavelength in the range of 500 to 560 nm, The optical conversion layer according to claim 8, comprising:

10. A color filter comprising the light conversion layer described in claim 8 or 9.

Images