TWI870381B - Inkjet ink for color filter, light conversion layer and color filter - Google Patents

Abstract

One aspect of the present invention is an inkjet ink for a color filter, which contains luminescent nanocrystals, a photopolymerizable compound and/or a thermosetting resin, and light scattering particles, wherein the luminescent nanocrystals have organic ligands on their surfaces, and the total content of the luminescent nanocrystals, the organic ligands, the photopolymerizable compound, the thermosetting resin and the light scattering particles is 41% by mass based on the total mass of the inkjet ink. The total content of luminescent nanocrystals and organic ligands is 21 parts by mass or more relative to 100 parts by mass of the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles, the content of organic ligands is 20 parts by mass or more relative to 100 parts by mass of the total content of luminescent nanocrystals and organic ligands, and the weight average molecular weight of the organic ligands is 1000 or less.

Description

Inkjet ink for color filter, light conversion layer and color filter

The present invention relates to an inkjet ink for a color filter, a light conversion layer and a color filter.

Previously, the pixel portion (color filter pixel portion) in a display such as a liquid crystal display device was manufactured by photolithography using, for example, a curable anti-etching agent material containing red organic pigment particles or green organic pigment particles and an alkali-soluble resin and/or an acrylic monomer.

In recent years, there has been a strong demand for low power consumption in displays, and therefore research is being actively conducted on methods of forming pixel portions such as red pixels and green pixels by using luminescent nanocrystals such as quantum dots, quantum rods, and other inorganic fluorescent particles instead of the red organic pigment particles or green organic pigment particles.

However, in the manufacturing method of the color filter using the photolithography method, due to the characteristics of the manufacturing method, there is a disadvantage that the anti-etching material outside the pixel part including the relatively expensive luminescent nanocrystals will be wasted. In this case, in order to avoid the waste of the anti-etching material, research is beginning to form the pixel part of the light conversion substrate by the inkjet method (Patent Document 1).

[Prior art literature] [Patent Literature]

[Patent Document 1] International Publication No. 2008/001693

In an inkjet ink containing luminescent nanoparticles, it is desirable to increase the content of luminescent nanoparticles (and organic ligands imparted to their surfaces) from the viewpoint of improving the optical properties of the pixel portion (e.g., improving the external quantum efficiency (EQE)). Moreover, although the film thickness of the pixel portion also needs to be thickened, in order to form the pixel portion by inkjet method, it is desirable to increase the content of non-volatile components in the inkjet ink. That is, when the content of non-volatile components in the inkjet ink is low (e.g., when it is less than 40% by mass based on the total mass of the inkjet ink), after the ink is printed on the pixel portion, the volatile components evaporate and the film thickness becomes thinner, so multiple printings are required, and there is a situation where the production efficiency of inkjet is significantly reduced. However, according to the research of the inventors, it is clear that the content of luminescent nanoparticles (and organic ligands given to their surfaces) is high (for example, 21 parts by mass or more relative to 100 parts by mass of non-volatile components of inkjet ink) and the inkjet ink with a high content of non-volatile components (for example, 41% by mass or more based on the total mass of the inkjet ink) has a tendency to increase in viscosity. Therefore, in addition to the problem of difficulty in ensuring a viscosity suitable for the formation of the pixel part, there is also the possibility of increased viscosity (thickening) in the atmospheric gas environment.

Therefore, the object of the present invention is to provide an inkjet ink containing luminescent nanocrystals and a high content of non-volatile components, having a viscosity suitable for forming a pixel portion, and suppressing viscosity increase in an atmospheric gas environment, as well as an inkjet ink for a color filter, and a light conversion layer and a color filter using the inkjet ink.

One aspect of the present invention is an inkjet ink for a color filter, which contains luminescent nanocrystals, a photopolymerizable compound and/or a thermosetting resin, and light scattering particles, wherein the luminescent nanocrystals have organic ligands on their surfaces, and the total content of the luminescent nanocrystals, the organic ligands, the photopolymerizable compound, the thermosetting resin and the light scattering particles is 41% by mass based on the total mass of the inkjet ink. The total content of luminescent nanocrystals and organic ligands is 21 parts by mass or more relative to 100 parts by mass of the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles, the content of organic ligands is 20 parts by mass or more relative to 100 parts by mass of the total content of luminescent nanocrystals and organic ligands, and the weight average molecular weight of organic ligands is 1000 or less.

The inkjet ink for color filter of the present invention adopts the above-mentioned structure, so it is an inkjet ink containing luminescent nanocrystals, and the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles (hereinafter, these components are also collectively referred to as "non-volatile components") is high, and at the same time has a viscosity suitable for the formation of pixel parts, and can suppress the increase of viscosity in the atmospheric gas environment.

In the inkjet ink, the total content of luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles can be 70% by mass or more based on the total mass of the inkjet ink.

In the inkjet ink, the organic ligand may contain a polyoxyalkylene group.

Another aspect of the present invention is a light conversion layer, which includes a plurality of pixel portions and a light shielding portion disposed between the plurality of pixel portions, wherein the plurality of pixel portions have a luminescent pixel portion containing a cured product of the inkjet ink for the color filter.

The light conversion layer, as the light-emitting pixel portion, may include: a first light-emitting pixel portion, including light-emitting nanocrystals that absorb light with a wavelength in the range of 420nm to 480nm and emit light with a peak emission wavelength in the range of 605nm to 665nm; and a second light-emitting pixel portion, including light-emitting nanocrystals that absorb light with a wavelength in the range of 420nm to 480nm and emit light with a peak emission wavelength in the range of 500nm to 560nm.

The light conversion layer may further include a non-luminescent pixel portion containing light scattering particles.

Another aspect of the present invention relates to a color filter including the light conversion layer.

According to the present invention, there is provided an inkjet ink containing luminescent nanocrystals and a high content of non-volatile components, having a viscosity suitable for forming a pixel portion and suppressing viscosity increase in an atmospheric gas environment, as well as an inkjet ink for a color filter, and a light conversion layer and a color filter using the inkjet ink.

10: Pixel section

10a: First pixel portion

10b: Second pixel portion

10c: Third pixel unit

11a: The first luminescent nanocrystal

11b: Second luminescent nanocrystals

12a: First light scattering particles

12b: Second light scattering particles

12c: Third light scattering particles

13a: First hardening component

13b: Second hardening component

13c: Third hardening component

20: Light shielding part

30: Light conversion layer

40: Base material

100: Color filter

Figure 1 is a schematic cross-sectional view of a color filter in one embodiment of the present invention.

The following is a detailed description of the implementation of the present invention.

<Inkjet ink>

An inkjet ink in one embodiment contains luminescent nanocrystals, a photopolymerizable compound and/or a thermosetting resin, and light scattering particles. The inkjet ink is an inkjet ink for a color filter used to form a pixel portion of a color filter by inkjetting.

Since the inkjet ink of this embodiment is used to form the color filter pixel part by inkjet method, the color filter pixel part (light conversion layer) can be formed by using only the necessary amount at the necessary part without wasting relatively expensive luminescent nanocrystals, solvents and other materials.

[Luminescent nanocrystals]

Luminescent nanocrystals are nano-sized crystals that absorb excitation light and emit fluorescence or phosphorescence, for example, crystals with a maximum particle size of less than 100 nm as measured by a transmission electron microscope or a scanning electron microscope.

Luminescent nanocrystals, for example, can emit light of a wavelength different from the absorbed wavelength by absorbing light of a specified wavelength (fluorescence or phosphorescence). Luminescent nanocrystals can be red luminescent nanocrystals (red luminescent nanocrystals) that emit light with a peak luminescence wavelength in the range of 605nm to 665nm (red light), green luminescent nanocrystals (green luminescent nanocrystals) that emit light with a peak luminescence wavelength in the range of 500nm to 560nm (green light), or blue luminescent nanocrystals (blue luminescent nanocrystals) that emit light with a peak luminescence wavelength in the range of 420nm to 480nm (blue light). In this embodiment, the inkjet ink preferably includes at least one of the luminescent nanocrystals. Moreover, the light absorbed by the luminescent nanocrystals may be, for example, light with a wavelength in the range of 400 nm or more and less than 500 nm (particularly light with a wavelength in the range of 420 nm to 480 nm) (blue light), or light with a wavelength in the range of 200 nm to 400 nm (ultraviolet light). In addition, the luminescent peak wavelength of the luminescent nanocrystals may be confirmed in the fluorescence spectrum or phosphorescence spectrum measured using a spectrofluorescence photometer, for example.

The red luminescent nanoparticles preferably have a luminescent peak wavelength below 665nm, below 663nm, below 660nm, below 658nm, below 655nm, below 653nm, below 651nm, below 650nm, below 647nm, below 645nm, below 643nm, below 640nm, below 637nm, below 635nm, below 632nm, or below 630nm, and preferably have a luminescent peak wavelength above 628nm, above 625nm, above 623nm, above 620nm, above 615nm, above 610nm, above 607nm, or above 605nm. These upper and lower limits can be combined arbitrarily. In addition, in the same description below, the upper and lower limits recorded separately can also be combined arbitrarily.

The green luminescent nanocrystals preferably have a luminescent peak wavelength below 560nm, below 557nm, below 555nm, below 550nm, below 547nm, below 545nm, below 543nm, below 540nm, below 537nm, below 535nm, below 532nm, or below 530nm, and preferably have a luminescent peak wavelength above 528nm, above 525nm, above 523nm, above 520nm, above 515nm, above 510nm, above 507nm, above 505nm, above 503nm, or above 500nm.

The blue luminescent nanocrystals preferably have a luminescent peak wavelength below 480nm, below 477nm, below 475nm, below 470nm, below 467nm, below 465nm, below 463nm, below 460nm, below 457nm, below 455nm, below 452nm, or below 450nm, and preferably have a luminescent peak wavelength above 450nm, above 445nm, above 440nm, above 435nm, above 430nm, above 428nm, above 425nm, above 422nm, or above 420nm.

According to the solution of the Schrodinger wave equation of the well-type potential model, the wavelength (luminescence color) of the light emitted by the luminescent nanocrystal depends on the size of the luminescent nanocrystal (such as the particle diameter), but also depends on the energy gap of the luminescent nanocrystal. Therefore, the luminescence color can be selected by changing the constituent materials and size of the luminescent nanocrystal used.

The luminescent nanocrystals may be luminescent nanocrystals containing semiconductor materials (luminescent semiconductor nanocrystals). Examples of luminescent semiconductor nanocrystals include quantum dots and quantum rods. Among these, quantum dots are preferred from the perspective of easy control of the luminescent spectrum, ensuring reliability, reducing production costs, and improving mass productivity.

The light-emitting semiconductor nanocrystal may be composed only of a core including a first semiconductor material, or may have a core including the first semiconductor material and a shell including a second semiconductor material different from the first semiconductor material and covering at least a portion of the core. In other words, the structure of the light-emitting semiconductor nanocrystal may be a structure composed only of a core (core structure) or a structure including a core and a shell (core/shell structure). Moreover, in addition to the shell (first shell) including the second semiconductor material, the light-emitting semiconductor nanocrystal may also have a shell (second shell) including a third semiconductor material different from the first semiconductor material and the second semiconductor material and covering at least a portion of the core. In other words, the structure of the light-emitting semiconductor nanocrystal may be a structure including a core, a first shell, and a second shell (core/shell/shell structure). The core and shell can be mixed crystals containing two or more semiconductor materials (such as CdSe+CdS, CIS+ZnS, etc.).

The luminescent nanocrystals preferably contain at least one semiconductor material selected from the group consisting of II-VI semiconductors, III-V semiconductors, I-III-VI semiconductors, IV semiconductors, and I-II-IV-VI semiconductors as the semiconductor material.

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, CdZnSe S, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe; GaN, GaP, GaAs, GaSb, AlN, Al P, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InA lPSb; SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; Si, Ge, SiC, SiGe, AgInSe _2. CuGaSe ₂ , CuInS ₂ , CuGaS ₂ , CuInSe ₂ , AgInS ₂ , AgGaSe ₂ , AgGaS ₂ , C, Si and Ge. From the viewpoint of easy control of luminescence spectrum, ensuring reliability, reducing production cost and improving mass productivity, the luminescent semiconductor nanocrystals preferably 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, AgInS ₂ , AgInSe ₂ , AgInTe ₂ , AgGaS ₂ , AgGaSe ₂ , AgGaTe ₂ , CuInS _{2 , CuInSe 2 ,} CuInTe ₂ , CuGaS ₂ , CuGaSe _{2 , CuGaTe 2 ,} Si, C, Ge and Cu ₂ ZnSnS ₄ .

As red luminescent semiconductor nanoparticles, for example, there can be listed CdSe nanoparticles, nanoparticles with a core/shell structure in which the shell is CdS and the inner core is CdSe, nanoparticles with a core/shell structure in which the shell is CdS and the inner core is ZnSe, nanoparticles of a mixed crystal of CdSe and ZnS, nanoparticles of InP, nanoparticles with a core/shell structure in which the shell is ZnS and the inner core is InP, nanoparticles with a core/shell structure in which the shell is ZnS and the inner core is InP, and nanoparticles with a core/shell structure in which the shell is ZnS and the inner core is InP. Nanocrystals with a mixed crystal of ZnS and ZnSe and an inner core of InP, nanocrystals with a mixed crystal of CdSe and CdS, nanocrystals with a mixed crystal of ZnSe and CdS, nanocrystals with a core/shell/shell structure and a first shell of ZnSe, a second shell of ZnSe, and an inner core of InP, nanocrystals with a core/shell/shell structure and a first shell of ZnS and ZnSe, a second shell of ZnS, and an inner core of InP, etc.

Green luminescent semiconductor nanoparticles include, for example, CdSe nanoparticles, nanoparticles of mixed crystals of CdSe and ZnS, nanoparticles having a core/shell structure in which the shell is ZnS and the inner core is InP, nanoparticles having a core/shell structure in which the shell is a mixed crystal of ZnS and ZnSe and the inner core is InP, nanoparticles having a core/shell/shell structure in which the first shell is ZnSe, the second shell is ZnS, and the inner core is InP, nanoparticles having a core/shell/shell structure in which the first shell is a mixed crystal of ZnS and ZnSe, the second shell is ZnS, and the inner core is InP, and nanoparticles having a core/shell/shell structure in which the first shell is a mixed crystal of ZnS and ZnSe, the second shell is ZnS, and the inner core is InP.

Examples of blue-light-emitting semiconductor nanoparticles include ZnSe nanoparticles, ZnS nanoparticles, nanoparticles having a core/shell structure in which the shell is ZnSe and the inner core is ZnS, nanoparticles having a core/shell structure in which the shell is ZnS and the inner core is InP, and nanoparticles having a core/shell structure in which the shell is ZnS and the inner core is InP. Mixed crystals of ZnS and ZnSe, nanocrystals with an inner core of InP, nanocrystals with a core/shell/shell structure and a first shell of ZnSe, a second shell of ZnS, and an inner core of InP, mixed crystals of ZnS and ZnSe, a second shell of ZnS, and an inner core of InP, etc.

Semiconductor nanoparticles have the same chemical composition, and by changing their own average particle size, the color of the light that the particles should emit can be changed to red or green. Moreover, Semiconductor nanoparticles as themselves are preferably used with minimal adverse effects on the human body. When semiconductor nanoparticles containing cadmium, selenium, etc. are used as luminescent nanoparticles, it is better to select semiconductor nanoparticles that do not contain the above elements (cadmium, selenium, etc.) as much as possible and use them alone, or use them in combination with other luminescent nanoparticles to minimize the above elements.

The shape of the luminescent nanocrystals is not particularly limited and can be any geometric shape or any irregular shape. The shape of the luminescent nanocrystals can be, for example, spherical, elliptical, pyramidal, disk-shaped, dendrite-shaped, mesh-shaped, rod-shaped, etc. However, from the perspective of further improving the uniformity and fluidity of the inkjet ink, it is preferred to use particles with less directionality as particle shapes (such as spherical, regular tetrahedral, etc.) as luminescent nanocrystals.

From the perspective of easy acquisition of desired wavelength luminescence and excellent dispersibility and storage stability, the average particle size (volume average diameter) of the luminescent nanocrystals can be 1 nm or more, 1.5 nm or more, or 2 nm or more. From the perspective of easy acquisition of desired luminescent wavelength, it can be 40 nm or less, 30 nm or less, or 20 nm or less. The average particle size (volume average diameter) of the luminescent nanocrystals is measured using a transmission electron microscope or a scanning electron microscope, and the volume average diameter is calculated to obtain the average particle size.

From the viewpoint of dispersion stability, the luminescent nanocrystals have organic ligands on their surfaces. The organic ligands can be, for example, coordinated and bonded to the surfaces of the luminescent nanocrystals. In other words, the surfaces of the luminescent nanocrystals can be passivated by the organic ligands. Furthermore, when the inkjet ink further contains a polymer dispersant described later, the luminescent nanocrystals can have the polymer dispersant on their surfaces. In this embodiment, for example, the organic ligands can be removed from the luminescent nanocrystals having the organic ligands, and the polymer dispersant can be bonded to the surfaces of the luminescent nanocrystals by exchanging the organic ligands with the polymer dispersant. However, from the viewpoint of dispersion stability when forming the inkjet ink, it is preferable to prepare the polymer dispersant for the luminescent nanocrystals in a state of being coordinated with the organic ligands.

The organic ligand may include a functional group (hereinafter also referred to as an "affinity group") for ensuring affinity with a photopolymerizable compound, a thermosetting resin, an organic solvent, etc. The affinity group may be a substituted or unsubstituted aliphatic alkyl group. The aliphatic alkyl group may be a straight chain type or a branched structure. Moreover, the aliphatic alkyl group may have an unsaturated bond or may not have an unsaturated bond. The substituted aliphatic alkyl group may be a group in which a part of the carbon atoms of the aliphatic alkyl group is substituted by an oxygen atom. The substituted aliphatic alkyl group may include, for example, a (poly)oxyalkylene group.

The organic ligand preferably includes a polyoxyalkylene group. A polyoxyalkylene group is a divalent group formed by two or more alkylene groups linked by an ether bond, and has multiple oxyalkylene structures (oxyalkylene groups). The multiple alkylene groups constituting the polyoxyalkylene group may be the same or different. The alkylene group may be a straight chain or have a branched structure.

The carbon number of the alkylene group may be, for example, 1 or more, 2 or more, or 3 or more, and may be 5 or less, 4 or less, or 3 or less. The alkylene group is preferably an ethylene group, a propylene group, or a butylene group. That is, the polyoxyalkylene group preferably has at least one selected from the group consisting of an oxyalkylene structure having an ethylene group (oxyethylene structure), an oxyalkylene structure having a propylene group (oxypropylene structure), and an oxyalkylene structure having a butylene group (oxybutylene structure).

The polyoxyalkylene group preferably has an oxyalkylene structure represented by the following formula (1).

In formula (1), ^R1 and ^R2 each independently represent a hydrogen atom, a methyl group or an ethyl group, and * represents a bond. When one of ^R1 and ^R2 is a methyl group or an ethyl group, the other is preferably a hydrogen atom. ^R1 and ^R2 are preferably a hydrogen atom or a methyl group. More preferably, an oxyethyl structure in which ^R1 and ^R2 are hydrogen atoms, or an oxypropyl structure in which one of ^R1 and ^R2 is a methyl group and the other is a hydrogen atom.

When the polyoxyalkylene group has a plurality of structures represented by the formula (1), the plurality of R ^1s may be the same or different, and the plurality of R ^2s may be the same or different.

The degree of polymerization of the polyoxyalkylene group may be, for example, 2 or more, 4 or more, or 6 or more, and may be 40 or less, 30 or less, or 20 or less. Here, the degree of polymerization of the polyoxyalkylene group refers to the number of repetitions of the oxyalkylene structure (the number of alkylene groups linked by ether bonds; in the case of containing two or more oxyalkylene groups (oxyalkylene structures), the total number of these).

When the polyoxyalkylene group contains repetitions of an oxyethylene structure, the number of repetitions of the oxyethylene structure may be 2 or more, 4 or more, or 6 or more, and may be 40 or less, 30 or less, or 20 or less.

When the polyoxyalkylene group contains repetitions of an oxypropylene structure, the number of repetitions of the oxypropylene structure may be 2 or more, 4 or more, or 6 or more, and may be 40 or less, 30 or less, or 20 or less.

The polyoxyalkylene group may be included in the main chain of the organic ligand. Here, the main chain refers to the longest of the molecular chains constituting the organic ligand.

The organic ligand preferably includes a functional group capable of bonding to the luminescent nanocrystals (functional groups for ensuring adsorption to the luminescent nanocrystals). Examples of the functional groups capable of bonding to the luminescent nanocrystals include hydroxyl groups, amine groups, carboxyl groups, thiol groups, phosphoric acid groups, phosphonic acid groups, phosphine groups, phosphine oxide groups, and alkoxysilane groups. These functional groups can bond to the luminescent nanocrystals via coordination bonds, etc.

The number of functional groups capable of bonding to luminescent nanocrystals in the organic ligands may be 1 to 3, 1 to 2, or 1. At least one of the functional groups capable of bonding to luminescent nanocrystals in the organic ligands on the surface of luminescent nanocrystals may be a functional group that bonds to luminescent nanocrystals. Moreover, when the organic ligands contain multiple functional groups capable of bonding to luminescent nanocrystals, some of the multiple functional groups may not bond to the luminescent nanocrystals.

The functional group capable of bonding to the luminescent nanoparticles may be present at at least one end of the main chain of the organic ligand. That is, the organic ligand may include a functional group capable of bonding to the luminescent nanoparticles at at least one end of the main chain.

The organic ligand may have a hydrogen-bonding group. Here, the hydrogen-bonding functional group refers to a group having a hydrogen atom that can form a hydrogen bond with a carbonyl group or the like. The hydrogen-bonding group may be a group that can bond with the luminescent nanoparticles. The organic ligand present on the surface of the luminescent nanoparticles preferably has a hydrogen-bonding group that is not bonded to the luminescent nanoparticles. Examples of hydrogen-bonding groups include monovalent groups such as hydroxyl groups, amine groups, carboxyl groups, and thiol groups, and divalent groups such as amide groups (-NHCO-).

The organic ligand may have one or more first functional groups capable of bonding to the luminescent nanocrystals at one end of the main chain, and a second functional group different from the first functional group at the other end of the main chain. The first functional group may be the same as the functional group capable of bonding to the luminescent nanocrystals. The number of the first functional group may be 1 or more, 2 or more, or 2. The second functional group may be the same as the functional group capable of bonding to the luminescent nanocrystals, or may be another group different from the functional group. The other groups may be, for example, alkyl, cycloalkyl, or aryl. The number of the second functional group may be 1 or more, or 1.

In addition to the polyoxyalkylene group, the main chain may also have a substituted or unsubstituted alkyl group. The number of carbon atoms in the substituted or unsubstituted alkyl group may be, for example, 1 to 10. In the substituted alkyl group, part of the carbon atoms may be substituted by a sulfur atom, a nitrogen atom, or a carbonyl group.

In one embodiment, the organic ligand may be a compound represented by the following formula (1-1).

[Chemistry 2]

In formula (1-1), p represents an integer from 0 to 50, and q represents an integer from 0 to 50. It is preferred that at least one of p and q is greater than 1, and it is more preferred that both p and q are greater than 1.

In one embodiment, the organic ligand may be an organic ligand represented by the following formula (1-2).

In formula (1-2), r represents an integer from 1 to 50.

In the organic ligand represented by formula (1-2), r can be an integer from 1 to 20, an integer from 3 to 15, an integer from 5 to 10, or 7.

The organic ligand may be a ligand having two or more functional groups capable of bonding to the luminescent nanoparticles. That is, in one embodiment, the organic ligand may be a compound represented by the following formula (1-3).

In formula (1-3), ^A1 and ^A2 each independently represent a monovalent group that may include the functional group capable of bonding to the luminescent nanocrystal, R represents a hydrogen atom, a methyl group or an ethyl group, ^L1 and ^L2 each independently represent a substituted or unsubstituted alkylene group, and s represents an integer greater than 0. Among them, at least one of ^A1 and ^A2 includes the functional group capable of bonding to the luminescent nanocrystal, and the total number of the functional groups capable of bonding to the luminescent nanocrystal in ^A1 and ^A2 is 2 or more. In the case where ^A1 or ^A2 is a group that does not include a functional group capable of bonding to the luminescent nanocrystal, ^A1 or ^A2 may be, for example, a hydrogen atom.

The number of functional groups capable of bonding to the luminescent nanocrystals in the monovalent groups represented by ^A1 and ^A2 can be 1 or more than 2, and can be 4 or less, or can be 2. The functional group capable of bonding to the luminescent nanocrystals is preferably at least one selected from the group consisting of a hydroxyl group and a carboxyl group.

In one embodiment, it is preferred that the number of functional groups capable of bonding to luminescent nanocrystals in the monovalent group represented by ^A1 is 2, and the number of functional groups capable of bonding to luminescent nanocrystals in the monovalent group represented by ^A2 is 1. In this case, it is more preferred that both of the two functional groups capable of bonding to luminescent nanocrystals in the monovalent group represented by ^A1 are carboxyl groups, and the functional group capable of bonding to luminescent nanocrystals in the monovalent group represented by ^A2 is a hydroxyl group.

In another embodiment, it is preferred that the number of functional groups capable of bonding to the luminescent nanocrystals in the monovalent group represented by ^A1 is 2, and ^A2 is a hydrogen atom (i.e., the number of functional groups capable of bonding to the luminescent nanocrystals in the monovalent group represented by ^A2 is 0). In this case, it is more preferred that both of the two functional groups capable of bonding to the luminescent nanocrystals in the monovalent group represented by ^A1 are carboxyl groups.

The carbon number of the alkylene group represented by L may be, for example, 1 to 10. In the alkylene group represented by L, a portion of the carbon atoms (methylene) may be substituted by heteroatoms. When L is a substituted alkylene group, a portion of the carbon atoms (methylene) in the alkylene group is preferably substituted by at least one heteroatom selected from the group consisting of oxygen atoms, sulfur atoms, and nitrogen atoms, and more preferably substituted by sulfur atoms. s may be, for example, an integer greater than 1, greater than 3, or greater than 5, or an integer less than 100, less than 20, or less than 10.

The organic ligand may be a compound represented by the following formula (1-4).

In formula (1-4), x and y are each independently an integer greater than 0, z is an integer greater than 1, and ^A1 , ^A2 and s have the same meanings as ^A1 , ^A2 and s in formula (1-3). At least one of x and y is an integer greater than 1.

x can be an integer less than 3 or less than 2, and can be 1 or 0. y can be an integer greater than 1, greater than 2, or greater than 3, and can be an integer less than 5, less than 4, or less than 3, and can be 3. z can be an integer less than 4, less than 3, or less than 2, and can be 1.

The organic ligand may be a compound represented by the following formula (1-5) or (1-6).

In formulas (1-5) and (1-6), s has the same meaning as s in formula (1-3).

Examples of organic ligands containing functional groups capable of bonding to luminescent nanoparticles include TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), lauric acid, oleic acid, oleylamine, octylamine, trioctylamine, hexadecylamine, octanethiol, dodecanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), and octylphosphonic acid (OPA).

In one embodiment, the organic ligand may be an organic ligand represented by the following formula (1-7).

In formula (1-7), n represents an integer of 0 to 50, and m represents an integer of 0 to 50. n is preferably 0 to 20, and more preferably 0 to 10. m is preferably 0 to 20, and more preferably 0 to 10. Preferably, at least one of n and m is 1 or more. That is, n+m is preferably 1 or more. n+m may be 10 or less. Z represents a substituted or unsubstituted alkylene group. The number of carbon atoms of the alkylene group may be, for example, 1 to 10. In the alkylene group represented by Z, a portion of the carbon atoms may be substituted by a heteroatom, or may be substituted by at least one heteroatom selected from the group consisting of an oxygen atom, a sulfur atom, and a nitrogen atom.

From the viewpoint of making the viscosity of the inkjet ink more suitable for forming the pixel portion, the weight average molecular weight of the organic ligand is 1000 or less, and may be 900 or less, 800 or less, 700 or less, or 600 or less, and may be 250 or more, 300 or more, 400 or more, 450 or more, 500 or more, or 550 or more. In addition, in this specification, the weight average molecular weight is the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

As luminescent nanoparticles, those dispersed in a colloidal form in an organic solvent, a photopolymerizable compound, etc. can be used. The surface of the luminescent nanoparticles dispersed in the organic solvent is preferably passivated by the organic ligand. Examples of organic solvents include cyclohexane, hexane, heptane, chloroform, toluene, octane, chlorobenzene, tetrahydronaphthalene, diphenyl ether, propylene glycol monomethyl ether acetate, butyl carbitol acetate, 1,4-butanediol diacetate, or a mixture thereof.

As luminescent nanocrystals, commercial products can be used. Commercial products of luminescent nanocrystals include, for example, indium phosphide/zinc sulfide from NN-Labs, D-dots, CuInS/ZnS, and InP/ZnS from Aldrich.

From the viewpoint of improving the external quantum efficiency maintenance rate more effectively, the content of the luminescent nanocrystals is preferably more than 10 parts by mass, more preferably more than 13 parts by mass, and further preferably more than 15 parts by mass, relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink (total content of non-volatile components). When the content of the luminescent nanocrystals exceeds 10 parts by mass, since excellent luminescence intensity can be obtained, such an inkjet ink can be preferably used as a color filter. From the viewpoint of better ejection stability, the content of the luminescent nanocrystals is preferably 60 parts by mass or less, and may be 50 parts by mass or less, 40 parts by mass or less, or 35 parts by mass or less, relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink (total content of non-volatile components). The content of the luminescent nanocrystals relative to the total content (total content of non-volatile components) of 100 parts by mass of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink may be more than 10 parts by mass and less than 60 parts by mass, 13 parts by mass to 60 parts by mass, 15 parts by mass to 60 parts by mass, more than 10 parts by mass and less than 50 parts by mass, more than 10 parts by mass and less than 40 parts by mass, or more than 10 parts by mass and less than 35 parts by mass.

The total content of luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink (total content of non-volatile components) is 41% by mass or more, based on the total mass of the inkjet ink, and can be 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, or 95% by mass or more, and can also be 100% by mass. When the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink (total content of non-volatile components) is 70% by mass or more based on the total mass of the inkjet ink, it can be preferably used as a solvent-free inkjet ink.

When the inkjet ink contains a photopolymerizable compound and does not contain a thermosetting resin, the total content of the non-volatile components is the total content of the luminescent nanoparticles, the organic ligands, the photopolymerizable compound, and the light scattering particles. Moreover, when the inkjet ink contains a thermosetting resin and does not contain a photopolymerizable compound, the total content of the non-volatile components is the total content of the luminescent nanoparticles, the organic ligands, the thermosetting resin, and the light scattering particles.

The inkjet ink may contain two or more of red, green and blue luminescent nanocrystals as luminescent nanocrystals, but preferably contains only one of these particles. When the inkjet ink contains red luminescent nanocrystals, the content of green luminescent nanocrystals and the content of blue luminescent nanocrystals are preferably 10% by mass or less, and more preferably 0% by mass, based on the total mass of the luminescent nanocrystals. When the inkjet ink contains green luminescent nanocrystals, the content of red luminescent nanocrystals and the content of blue luminescent nanocrystals are preferably 10% by mass or less, and more preferably 0% by mass, based on the total mass of the luminescent nanocrystals.

With respect to 100 parts by mass of the total content of the luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink, the total content of the luminescent nanoparticles and organic ligands is 21 parts by mass or more, and may be 25 parts by mass or more, 27 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 45 parts by mass or more or 50 parts by mass or more, and may be 70 parts by mass or less, 65 parts by mass or less, 60 parts by mass or less or 55 parts by mass or less.

From the viewpoint of suppressing the viscosity increase of the inkjet ink caused by atmospheric exposure, the content of the organic ligand is 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, or 32 parts by mass or more, and may be 50 parts by mass or less, 45 parts by mass or less, 40 parts by mass or less, or 38 parts by mass or less, relative to 100 parts by mass of the total content of the luminescent nanocrystals and the organic ligand. When the content of the organic ligand is 50 parts by mass or less relative to 100 parts by mass of the total content of the luminescent nanocrystals and the organic ligand, the content of the luminescent nanocrystals in the inkjet ink can be relatively increased, which is preferred. In this specification, the content of organic ligands relative to the total content of luminescent nanocrystals and organic ligands 100 parts by mass is defined as the probability (ratio of organic compounds) obtained by TG-DTA measurement of a mixture containing luminescent nanocrystals and organic ligands. The mixture containing luminescent nanocrystals and organic ligands can be obtained by adding a poor solvent of the mixture to an inkjet ink, allowing the mixture to settle, and then drying it.

[Photopolymerizable compounds]

The photopolymerizable compound of the present embodiment is a compound that polymerizes by irradiation with light, for example, a photoradical polymerizable compound or a photocationic ion polymerizable compound. The photopolymerizable compound may be a photopolymerizable monomer or oligomer. These may be used together with a photopolymerization initiator. The photoradical polymerizable compound may be used together with a photoradical polymerization initiator, and the photocationic ion polymerizable compound may be used together with a photocationic ion polymerization initiator. In other words, the inkjet ink may contain a photopolymerizable component comprising a photopolymerizable compound and a photopolymerization initiator, may contain a photoradical polymerizable component comprising a photoradical polymerizable compound and a photoradical polymerization initiator, and may also contain a photocationic ion polymerizable component comprising a photocationic ion polymerizable compound and a photocationic ion polymerization initiator. A photo-radical polymerizable compound and a photo-cationic polymerizable compound may be used together, a compound having both photo-radical polymerizable properties and photo-cationic polymerizable properties may be used, and a photo-radical polymerization initiator and a photo-cationic polymerization initiator may be used together. A photo-polymerizable compound may be used alone or in combination of two or more.

As photo-free radical polymerizable compounds, for example, monomers having ethylenic unsaturated groups (hereinafter also referred to as "ethylenic unsaturated monomers"), monomers having isocyanate groups, etc. can be listed. Here, ethylenic unsaturated monomers refer to monomers having ethylenic unsaturated bonds (carbon-carbon double bonds). As ethylenic unsaturated monomers, for example, monomers having ethylenic unsaturated groups such as vinyl, vinylene, and vinylidene can be listed. Monomers having these groups are sometimes referred to as "vinyl monomers".

The number of ethylenically unsaturated bonds in the ethylenically unsaturated monomer (e.g., the number of ethylenically unsaturated groups) is, for example, 1 to 3. The ethylenically unsaturated monomer may be used alone or in combination. From the viewpoint of easily taking into account both excellent ejection stability and excellent curability and further improving the external quantum efficiency, the photopolymerizable compound may include a monomer having 1 or 2 ethylenically unsaturated groups and a monomer having 2 or 3 ethylenically unsaturated groups. That is, the ethylenically unsaturated monomer may include at least one combination selected from the group consisting of a monofunctional monomer and a difunctional monomer, a monofunctional monomer and a trifunctional monomer, a difunctional monomer and a difunctional monomer, and a difunctional monomer and a trifunctional monomer. In this embodiment, the photopolymerizable compound preferably contains two or more monomers having two ethylenically unsaturated bonds.

As ethylenically unsaturated groups, in addition to vinyl, vinylidene and vinylidene groups, (meth)acryl groups and the like can also be cited. In addition, in this specification, "(meth)acryl group" refers to "acryl group" and its corresponding "methacryl group". The same applies to "(meth)acrylate" and "(meth)acrylamide".

Examples of the monofunctional monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (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, and dimethylhexyl (meth)acrylate. Ethoxyethoxyethyl acrylate, isobornyl (meth)acrylate, dicyclopentyl (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-acryloxyethyl) succinate, mono(2-methacryloxyethyl) succinate, N-[2-(acryloxy)ethyl]phthalimide, N-[2-(acryloxy)ethyl]tetrahydrophthalimide, 4-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl acrylate, and the like. Among these, ethoxyethoxyethyl (meth)acrylate can be preferably used.

Specific examples of monomers having two ethylenically unsaturated groups (difunctional monomers) include 1,3-butanediol 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, esters, di(meth)acrylates in which two hydroxyl groups of tri(2-hydroxyethyl)isocyanurate are substituted with (meth)acryloyloxy groups, di(meth)acrylates in which two hydroxyl groups of a diol are substituted with (meth)acryloyloxy groups, obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol, di(meth)acrylates in which two hydroxyl groups of a diol are substituted with (meth)acryloyloxy groups, obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of bisphenol A, Di(meth)acrylate substituted with (meth)acryloyloxy, di(meth)acrylate in which two hydroxyl groups of triol are substituted with (meth)acryloyloxy, di(meth)acrylate in which two hydroxyl groups of diol are substituted with (meth)acryloyloxy, etc., obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trihydroxymethylpropane, and di(meth)acrylate in which two hydroxyl groups of diol are substituted with (meth)acryloyloxy, etc. Among these, dipropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol diacrylate are preferably used.

Specific examples of monomers having three ethylenically unsaturated groups (trifunctional monomers) include glycerol tri(meth)acrylate, trihydroxymethylethane tri(meth)acrylate, etc. Among these, glycerol tri(meth)acrylate is preferably used.

Examples of photo-ion polymerizable compounds include epoxy compounds, cyclohexane compounds, vinyl ether compounds, etc.

Examples of epoxy compounds include bisphenol A epoxy compounds, bisphenol F epoxy compounds, phenol novolac epoxy compounds, aliphatic epoxy compounds such as trihydroxymethylpropane polyglycidyl ether and neopentyl glycol diglycidyl ether, and alicyclic epoxy compounds such as 1,2-epoxy-4-vinylcyclohexane and 1-methyl-4-(2-methyloxyheterocyclopropyl)-7-oxoheterobicyclo[4.1.0]heptane.

As the epoxy compound, a commercial product may be used. As the commercial product of the epoxy compound, for example, "Celloxide 2000", "Celloxide 3000", "Celloxide 4000" etc. manufactured by Daicel Chemical Industries Co., Ltd. may be used.

Examples of cationically polymerizable cyclohexyloxybutane compounds include 2-ethylhexylcyclohexyloxybutane, 3-hydroxymethyl-3-methylcyclohexyloxybutane, 3-hydroxymethyl-3-ethylcyclohexyloxybutane, 3-hydroxymethyl-3-propylcyclohexyloxybutane, 3-hydroxymethyl-3-n-butylcyclohexyloxybutane, 3-hydroxymethyl-3-phenylcyclohexyloxybutane, 3-hydroxymethyl-3-benzylcyclohexyloxybutane, 3-hydroxyethyl-3-cyclohexyloxybutane, -Methyloxycyclobutane, 3-hydroxyethyl-3-ethyloxycyclobutane, 3-hydroxyethyl-3-propyloxycyclobutane, 3-hydroxyethyl-3-phenyloxycyclobutane, 3-hydroxypropyl-3-methyloxycyclobutane, 3-hydroxypropyl-3-ethyloxycyclobutane, 3-hydroxypropyl-3-propyloxycyclobutane, 3-hydroxypropyl-3-phenyloxycyclobutane, 3-hydroxybutyl-3-methyloxycyclobutane, etc.

As the cyclooxetane compound, a commercial product may be used. As the commercial product of the cyclooxetane compound, for example, the Aron Oxetane Series ("OXT-101", "OXT-212", "OXT-121", "OXT-221", etc.) manufactured by Toagosei Co., Ltd.; "Celloxide 2021", "Celloxide 2021A", "Celloxide 2021P", "Celloxide 2080", "Celloxide 2081", "Celloxide 2083", "Celloxide 2085", "Epolead GT300", "Epolead GT301", "Epolead GT302", "Epolead GT400", "Epolead GT401" and "Epolead GT403" manufactured by Dow Chemical Co., Ltd. "Cyracure UVR-6105", "Cyracure UVR-6107", "Cyracure UVR-6110", "Cyracure UVR-6128", "ERL4289" and "ERL4299" manufactured by Cyracure Chemical Japan Co., Ltd. In addition, known cyclohexane compounds (such as cyclohexane compounds described in Japanese Patent Laid-Open No. 2009-40830, etc.) can also be used.

As the vinyl ether compound, there can be listed 2-hydroxyethyl vinyl ether, triethylene glycol vinyl monoether, tetraethylene glycol divinyl ether, trihydroxymethylpropane trivinyl ether, etc.

Furthermore, as the photopolymerizable compound in this embodiment, the photopolymerizable compound described in paragraphs 0042 to 0049 of Japanese Patent Publication No. 2013-182215 can also be used.

From the perspective of easily obtaining a pixel portion (cured product of inkjet ink) with excellent reliability, the photopolymerizable compound may be alkali-insoluble. In this specification, the photopolymerizable compound being alkali-insoluble means that the amount of the photopolymerizable compound dissolved in a 1% potassium hydroxide aqueous solution at 25°C is 30% by mass or less based on the total mass of the photopolymerizable compound. The solubility of the photopolymerizable compound is preferably 10% by mass or less, and more preferably 3% by mass or less.

From the viewpoint of easily obtaining a viscosity suitable for inkjet ink, the viewpoint of improving the curability of inkjet ink, and the viewpoint of improving the solvent resistance and abrasion resistance of the pixel portion (cured product of inkjet ink), the content of the photopolymerizable compound can be 10 parts by mass or more, 15 parts by mass or more, or even 20 parts by mass or more, relative to 100 parts by mass of the total content of the luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink. From the perspective of easily obtaining a viscosity appropriate for inkjet ink and obtaining better optical properties (e.g., the effect of suppressing the decrease in external quantum efficiency), the content of the photopolymerizable compound can be 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, relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink.

[Photopolymerization initiator]

The photopolymerization initiator is, for example, a photoradical polymerization initiator. As the photoradical polymerization initiator, a molecular cleavage type or dehydrogenation type photoradical polymerization initiator is preferred.

As the molecular cleavage type photoradical polymerization initiator, preferably used are benzoin isobutyl ether, 2,4-diethylthiothione, 2-isopropylthiothione, 2,4,6-trimethylbenzyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butane-1-one, bis(2,6-dimethoxybenzyl)-2,4,4-trimethylpentylphosphine oxide, (2,4,6-trimethylbenzyl)ethoxyphenylphosphine oxide, and the like. As molecular cleavage type photoradical polymerization initiators other than these, 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one and 2-methyl-1-(4-methylthiophenyl)-2-morpholinylpropane-1-one may also be used in combination.

As dehydrogenation type photo-radical polymerization initiators, benzophenone, 4-phenylbenzophenone, isophthalic acid ketone, 4-benzoyl-4'-methyl-diphenyl sulfide, etc. can be listed. Molecular cleavage type photo-radical polymerization initiators and dehydrogenation type photo-radical polymerization initiators can also be used together.

As the photocatalytic ion polymerization initiator, a commercial product may be used. Examples of commercial products include cobalt salt-based photocatalytic ion polymerization initiators such as "CPI-100P" manufactured by San-apro, acylphosphine oxide compounds such as "Lucirin TPO" manufactured by BASF, and "Irgacure 907", "Irgacure 819", "Irgacure 379EG", "Irgacure 184" and "Irgacure PAG290" manufactured by BASF.

From the perspective of the curability of the inkjet ink, the content of the photopolymerization initiator can be 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 relative to 100 parts by mass of the photopolymerizable compound. From the perspective of the temporal stability of the pixel portion (cured product of the inkjet ink), the content of the photopolymerization initiator can be 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 relative to 100 parts by mass of the photopolymerizable compound.

[Thermosetting resin]

In the present embodiment, the thermosetting resin is a resin that is cured by crosslinking with heat. The thermosetting resin is, for example, a resin that functions as a binder in a cured product. The thermosetting resin has a curing group. Examples of the curing group include an epoxy group, an oxycyclobutane group, an isocyanate group, an amino group, a carboxyl group, a hydroxymethyl group, etc. From the perspective of excellent heat resistance and storage stability of the cured product of the inkjet ink, and excellent adhesion to the light shielding portion (such as a black matrix) and the substrate, an epoxy group is preferred. The thermosetting resin may have one curing group or may have two or more curing groups.

In addition, thermosetting resins include resins having photo-radical polymerizability (polymerizes by light irradiation when used with a photo-radical polymerization initiator) and resins having photo-cationic polymerizability (polymerizes by light irradiation when used with a photo-cationic polymerization initiator). When the inkjet ink contains a thermosetting resin having photo-radical polymerizability and a photo-radical polymerization initiator, the thermosetting resin having photo-radical polymerizability is classified as a photo-radical polymerizable compound (photopolymerizable compound). When the inkjet ink contains a photo-cationically polymerizable thermosetting resin and a photo-cationically polymerizable initiator, the photo-cationically polymerizable thermosetting resin is classified as a photo-cationically polymerizable compound (photopolymerizable compound).

Thermosetting resins can be polymers of a single monomer (homopolymer) or copolymers of multiple monomers (copolymer). Furthermore, thermosetting resins can be any of random copolymers, block copolymers, or graft copolymers.

As a thermosetting resin, a compound having two or more thermosetting groups in one molecule can be used, and it is usually used in combination with a hardener. When a thermosetting resin is used, a catalyst (hardening accelerator) that can promote the thermosetting reaction can be further added. In other words, the inkjet ink can contain a thermosetting component including a thermosetting resin (and a hardener and a hardening accelerator used as needed). In addition to these, a polymer that itself has no polymerization reactivity can also be used.

As a compound having two or more thermosetting groups in one molecule, for example, an epoxy resin having two or more epoxy groups in one molecule (hereinafter also referred to as a "polyfunctional epoxy resin") can be used. "Epoxy resins" include both monomeric epoxy resins and polymeric epoxy resins. The number of epoxy groups in a polyfunctional epoxy resin in one molecule is preferably 2 to 50, and more preferably 2 to 20. The epoxy group can be any structure as long as it has an oxycyclopropane ring structure, and can be, for example, a glyceryl group, an oxyethyl group, an oxirane group, or the like. As epoxy resins, well-known polyvalent epoxy resins that can be cured by carboxylic acids can be listed. Such epoxy resins are widely disclosed in, for example, the "Epoxy Resin Handbook" edited by Masaaki Shinbo and published by the Daily Industry News (1987), and these can be used.

Examples of thermosetting resins having epoxy groups (including polyfunctional epoxy resins) include polymers of monomers having an oxycyclopropane ring structure and copolymers of monomers having an oxycyclopropane ring structure and other monomers. Specific examples of polyfunctional epoxy resins include polyglycidyl methacrylate, methyl methacrylate-glycidyl methacrylate copolymer, benzyl methacrylate-glycidyl methacrylate copolymer, n-butyl methacrylate-glycidyl methacrylate copolymer, 2-hydroxyethyl methacrylate-glycidyl methacrylate copolymer, (3-ethyl-3-oxycyclobutyl) methyl methacrylate-glycidyl methacrylate copolymer, and styrene- glycidyl methacrylate. Furthermore, as the thermosetting resin of this embodiment, the compounds described in paragraphs 0044 to 0066 of Japanese Patent Publication No. 2014-56248 may also be used.

As the polyfunctional epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, diphenyl ether type epoxy resin, hydroquinone type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, fluorene type epoxy resin, phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, trihydroxy epoxy resin, Phenylmethane type epoxy resin, trifunctional epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene phenol type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol A core-containing polyol type epoxy resin, polypropylene glycol type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, glyoxal type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, etc.

More specifically, examples include bisphenol A type epoxy resins such as "Epicoat 828" (manufactured by Nippon Epoxy Resin Co., Ltd.), bisphenol F type epoxy resins such as "YDF-175S" (manufactured by Tohto Chemical Co., Ltd.), brominated bisphenol A type epoxy resins such as "YDB-715" (manufactured by Tohto Chemical Co., Ltd.), bisphenol S type epoxy resins such as "EPICLON EXA1514" (manufactured by DIC Corporation), and bisphenol F type epoxy resins such as "YDF-175S" (manufactured by Tohto Chemical Co., Ltd.). C-1312" (manufactured by Tohto Chemical Industry Co., Ltd.), hydroquinone-type epoxy resins such as "Epiclon EXA4032", "HP-4770", "HP-4700", "HP-5000" (manufactured by DIC Corporation), naphthalene-type epoxy resins such as "Epicoat YX4000H" (manufactured by Nippon Epoxy Resin Co., Ltd.), Biphenyl epoxy resins such as "Epicoat 157S70" (manufactured by Nippon Epoxy Resin Co., Ltd.), bisphenol A novolac epoxy resins such as "Epicoat 154" (manufactured by Nippon Epoxy Resin Co., Ltd.), Phenol novolac epoxy resins such as the trade name "YDPN-638" (manufactured by Tohto Kasei Co., Ltd.), cresol novolac epoxy resins such as the trade name "YDCN-701" (manufactured by Tohto Kasei Co., Ltd.), dicyclopentadiene phenol epoxy resins such as the trade names "Epiclon HP-7200" and "HP-7200H" (manufactured by DIC Co., Ltd.), and the trade name "Epicoat 1032H60" (manufactured by Nippon Epoxy Trihydroxyphenylmethane epoxy resins such as "VG3101M80" (manufactured by Mitsui Chemicals Co., Ltd.), trifunctional epoxy resins such as "Epicoat 1031S" (manufactured by Nippon Epoxy Resin Co., Ltd.), tetraphenylethane epoxy resins such as "Denacol EX-411" (manufactured by Nagase Chemicals Co., Ltd.), hydrogenated bisphenol A epoxy resins such as "ST-3000" (manufactured by Tohto Chemicals Co., Ltd.), and "Epicoat 190P" (manufactured by Nippon Epoxy Resin Co., Ltd.) Glycidyl ester type epoxy resins such as "YH-434" (manufactured by Tohto Kasei Co., Ltd.), glycidylamine type epoxy resins such as "YDG-414" (manufactured by Tohto Kasei Co., Ltd.), alicyclic polyfunctional epoxy compounds such as "Epolead GT-401" (manufactured by Daicel Chemical Co., Ltd.), and triglycidyl isocyanate (TGIC) Hybrid epoxy resins, etc. Moreover, if necessary, "neotohto E" (manufactured by Tohto Kasei Co., Ltd.) can be mixed as an epoxy reactive diluent.

As the multifunctional epoxy resin, "FINEDIC A-247S", "FINEDIC A-254", "FINEDIC A-253", "FINEDIC A-229-30A", "FINEDIC A-261", "FINEDIC A249", "FINEDIC A-261" manufactured by DIC Corporation can be used. "FINEDIC A-266", "FINEDIC A-241", "FINEDIC M-8020", "EPICLON N-740", "EPICLON N-770", "EPICLON N-865", "EPICLON EXA-4850-150" (trade names), etc.

From the perspective of easily obtaining a suitable viscosity for inkjet ink, improving the curability of inkjet ink, and improving the solvent resistance and abrasion resistance of the pixel portion (cured product of inkjet ink), the weight average molecular weight of the thermosetting resin can be 750 or more, 1000 or more, or 2000 or more. From the perspective of achieving a suitable viscosity for inkjet ink, it can be 500000 or less, 300000 or less, or 200000 or less. However, the molecular weight after crosslinking is not limited to this.

From the viewpoint of easily obtaining a viscosity appropriate for inkjet ink, the viewpoint of improving the curability of inkjet ink, and the viewpoint of improving the solvent resistance and abrasion resistance of the pixel portion (cured product of inkjet ink), the content of the thermosetting resin can be 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or 20 parts by mass or more relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink. From the viewpoint that the viscosity of the inkjet ink will not become too high and the thickness of the pixel portion will not become too thick relative to the light conversion function, the content of the thermosetting resin can be less than 60 parts by mass, less than 50 parts by mass, less than 40 parts by mass, less than 30 parts by mass, or less than 20 parts by mass relative to the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink of 100 parts by mass.

[Hardener]

Examples of curing agents used to cure thermosetting resins include acid anhydrides, phenolic compounds, and amine compounds. These curing agents may be used alone or in combination of two or more. The curing agent preferably includes at least one selected from the group consisting of acid anhydrides, phenolic compounds, and amine compounds. Furthermore, when epoxy resin is used as a thermosetting resin, onium salts, organometallic complexes, tertiary amines, imidazoles, and the like may be used for self-polymerization.

Examples of acid anhydrides (acid anhydride hardeners) include 4-methylcyclohexane-1,2-dicarboxylic anhydride (4M-HHPA), 3-methylcyclohexane-1,2-dicarboxylic anhydride, cyclohexane-1,2-dicarboxylic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, 3-methyl-1,2,3,6-tetrahydrophthalic anhydride, 4-methyl-1,2,3,6-tetrahydrophthalic anhydride, Dicarboxylic anhydride, bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, methyl bicyclo[2.2.1]heptane-2,3-dicarboxylic anhydride, methyl-3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, 3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, etc.

Examples of phenolic compounds (phenolic curing agents) include bisphenol A, bisphenol F, bisphenol S, resorcinol, o-catechol, hydroquinone, fluorene bisphenol, 4,4'-biphenol, 4,4',4"-trihydroxytriphenylmethane, naphthalene diol, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, calix resorcinol aromatics, novolac type phenolic resins (e.g., phenol novolac resins, cresol novolac resins, bisphenol A novolac resins, Polyphenol novolac resins synthesized from polyhydroxy compounds and formaldehyde, represented by bisphenol S novolac resins and resorcinol novolac resins, naphthol-phenol co-phenol novolac resins, naphthol-cresol co-phenol novolac resins, naphthol novolac resins, and alkoxy aromatic ring-containing modified novolac resins (using formaldehyde to link phenol nuclei and polyphenol compounds containing alkoxy aromatic rings)), aralkyl type phenol resins (such as neophenol resins (xylok resin), phenol aralkyl resins such as phenol aralkyl resins and naphthol aralkyl resins), aromatic hydrocarbon formaldehyde resin modified phenol resins, dicyclopentadiene phenol addition resins, trihydroxymethylmethane resins, tetraphenylethane resins, biphenyl modified phenol resins (polyphenol compounds with a phenol nucleus linked by a dimethylene group), biphenyl modified naphthol resins (polyphenol compounds with a phenol nucleus linked by a dimethylene group), amines Polyphenol compounds such as triazine-modified phenol resins (polyphenol compounds using melamine, benzoguanamine, etc. to link phenol cores). From the perspective of excellent external quantum efficiency improvement effect, phenolic compounds preferably include novolac-type phenolic resins. As novolac-type phenolic resins, phenol novolac resins, cresol novolac resins, and bisphenol A novolac resins can be preferably used.

Specific examples of novolac-type phenolic resins include "PHENOLITE TD-2131" and "PHENOLITE TD-2090" (trade names) manufactured by DIC Co., Ltd., and "GPH-65" and "GPH-103" (trade names) manufactured by Nippon Kayaku Co., Ltd.

As amine compounds (amine curing agents), for example, there can be listed: aliphatic polyamines such as ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine, etc., aromatic polyamines such as m-xylylenediamine, diaminodiphenylmethane, phenylenediamine, etc., alicyclic polyamines such as 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, norbornanediamine, etc., dicyandiamide, linolenic acid dimer and polyamide resin synthesized from ethylenediamine.

Regarding the hardener, from the perspective of the external quantum efficiency and heat resistance of the cured product of the inkjet ink, an acid anhydride hardener is ideal, and from the perspective of the curability of the cured product of the inkjet ink and the viscosity stability of the inkjet ink, a phenol hardener is ideal.

The content of the hardener, for example, relative to 100 parts by mass of the total content of the luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink, can be 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. The content of the hardener, for example, relative to 100 parts by mass of the total content of the luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink, can be 1 part by mass or more, or 3 parts by mass or more.

[Hardening accelerator (hardening catalyst)]

Examples of curing accelerators (curing catalysts) used to cure thermosetting resins include phosphorus compounds, tertiary amine compounds, imidazole compounds, organic acid metal salts, Lewis acids, and amine complexes. Examples of phosphorus compounds include triphenylphosphine, tri-p-tolylphosphine, diphenylcyclohexylphosphine, and methyltributylphosphonium iodide. Examples of tertiary amine compounds include N,N-dimethylbenzylamine, 1,8-diazabicyclo(5,4,0)undecene-7, 1,5-diazabicyclo(4,3,0)nonene-5, and tris(dimethylaminomethyl)phenol. Examples of imidazole compounds include 1-cyanoethyl-2-ethyl-4-methylimidazole and 2-ethyl-4-methylimidazole.

From the perspective of easily obtaining a pixel portion (cured product of inkjet ink) with excellent reliability, the thermosetting resin may be alkali-insoluble. The thermosetting resin being alkali-insoluble means that the amount of the thermosetting resin dissolved in a 1 mass % potassium hydroxide aqueous solution at 25°C is 30 mass % or less based on the total mass of the thermosetting resin. The solubility of the thermosetting resin is preferably 10 mass % or less, and more preferably 3 mass % or less.

In this embodiment, the inkjet ink only needs to contain at least one of a photopolymerizable compound and a thermosetting resin, and may contain both a photopolymerizable compound and a thermosetting resin. When the inkjet ink contains a photopolymerizable compound, it may not contain a thermosetting resin. Furthermore, when the inkjet ink contains a thermosetting resin, it may not contain a photopolymerizable compound. From the perspective of the storage stability of the inkjet ink containing luminescent nanoparticles (such as quantum dots) and the durability (wet-heat stability, etc.) of the pixel portion (cured product of the inkjet ink), it is preferred to use a thermosetting resin among photopolymerizable compounds and thermosetting resins. From the perspective of the storage stability of the inkjet ink containing luminescent nanoparticles (such as quantum dots) and the ability to cure at a low temperature that is not susceptible to the deterioration of the quantum dots by heating, it is more preferred to use a photoradical polymerizable compound. From the perspective of being able to form a pixel portion (cured product of the inkjet ink) without being hindered by oxygen in the curing process, it is preferred to use a photocationic ion polymerizable compound.

When the inkjet ink contains a photopolymerizable compound and a thermosetting resin, from the viewpoint of easily obtaining a viscosity suitable for the inkjet ink, from the viewpoint of improving the curability of the inkjet ink, and from the viewpoint of improving the solvent resistance and abrasion resistance of the pixel portion (cured product of the inkjet ink), the total content of the photopolymerizable compound and the thermosetting resin can be 3 parts by mass or more, 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, or even 20 parts by mass or more relative to 100 parts by mass of the total content of the luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink. Furthermore, from the viewpoint that the viscosity of the inkjet ink will not become too high and the thickness of the pixel portion will not become too thick relative to the light conversion function, the total content of the photopolymerizable compound and the thermosetting resin can be less than 60 parts by mass, less than 40 parts by mass, or less than 20 parts by mass relative to the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink of 100 parts by mass.

[Light scattering particles]

Light scattering particles are, for example, optically inactive inorganic particles. When inkjet ink contains light scattering particles, light from a light source irradiating the pixel portion can be scattered, thereby obtaining excellent optical properties.

Examples of materials constituting the light scattering particles include: single metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, and gold; silicon dioxide, barium sulfate, barium carbonate, calcium carbonate, talc, clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, alumina, titanium oxide, and magnesium oxide. , barium oxide, aluminum oxide, bismuth oxide, zirconium oxide, zinc oxide and other metal oxides; magnesium carbonate, barium carbonate, bismuth subcarbonate, calcium carbonate and other metal carbonates; aluminum hydroxide and other metal hydroxides; barium zirconate, calcium zirconate, calcium titanium, barium titanium, strontium titanium and other complex oxides; bismuth subnitrate and other metal salts, etc. From the viewpoint of excellent ejection stability and better effect of improving external quantum efficiency, the light scattering particles preferably include at least one selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate, barium titanate and silicon dioxide, and more preferably include at least one selected from the group consisting of titanium oxide, zirconium oxide, zinc oxide and barium titanate.

The shape of light scattering particles can be spherical, filamentous, irregular, etc. However, as light scattering particles, it is better to use particles with less directionality as a particle shape (such as spherical, regular tetrahedral, etc.) from the perspective of further improving the uniformity, fluidity and light scattering of the inkjet ink and obtaining excellent ejection stability.

From the viewpoint of excellent ejection stability and a more excellent effect of improving external quantum efficiency, the average particle size (volume average diameter) of the light scattering particles in the inkjet ink may be 0.05 μm (50 nm) or more, 0.2 μm (200 nm) or more, or 0.3 μm (300 nm) or more. From the viewpoint of excellent ejection stability, the average particle size (volume average diameter) of the light scattering particles in the inkjet ink may be 1.0 μm (1000 nm) or less, 0.6 μm (600 nm) or less, or 0.4 μm (400 nm) or less. The average particle size (volume average diameter) of the light scattering particles in the inkjet ink may be 0.05μm~1.0μm, 0.05μm~0.6μm, 0.05μm~0.4μm, 0.2μm~1.0μm, 0.2μm~0.6μm, 0.2μm~0.4μm, 0.3μm~1.0μm, 0.3μm~0.6μm or 0.3μm~0.4μm. From the viewpoint of easily obtaining such an average particle size (volume average diameter), the average particle size (volume average diameter) of the light scattering particles used may be 0.05μm or more and 1.0μm or less. In this specification, the average particle size (volume average diameter) of the light scattering particles in the inkjet ink is measured using a dynamic light scattering Nanotrac particle size distribution meter and the volume average diameter is calculated. In addition, the average particle size (volume average diameter) of the light scattering particles used can be obtained by measuring the particle size of each particle using a transmission electron microscope or a scanning electron microscope and calculating the volume average diameter.

From the perspective of achieving a better effect of improving the external quantum efficiency, the content of light scattering particles in the inkjet ink can be 0.1 parts by mass or more, 1 part by mass or more, 5 parts by mass or more, 7 parts by mass or more, 10 parts by mass or more, or 12 parts by mass or more relative to 100 parts by mass of the total content of the luminescent nanoparticles, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink. From the perspective of excellent ejection stability and a more excellent effect of improving external quantum efficiency, the content of light scattering particles can be 60 parts by mass or less, 50 parts by mass or less, 40 parts by mass or less, 30 parts by mass or less, 25 parts by mass or less, 20 parts by mass or less, or 15 parts by mass or less, relative to 100 parts by mass of the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink. When the inkjet ink contains a polymer dispersant, the light scattering particles can be well dispersed even when the content of the light scattering particles is relatively high (for example, when it is set to about 60 parts by mass).

From the perspective of excellent external quantum efficiency improvement effect, the mass ratio of the content of light scattering particles to the content of luminescent nanocrystals (light scattering particles/luminescent nanocrystals) can be 0.01 or more, 0.02 or more, 0.05 or more, 0.07 or more, 0.1 or more, 0.2 or more, or 0.5 or more. From the perspective of more excellent external quantum efficiency improvement effect and excellent continuous ejection property (ejection stability) during inkjet printing, the mass ratio (light scattering particles/luminescent nanocrystals) can be 5.0 or less, 2.0 or less, or 1.5 or less.

From the perspective of easily obtaining an appropriate viscosity for inkjet ink, the content of inorganic components in the inkjet ink (for example, the total amount of luminescent nanocrystals and light scattering particles) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink. From the perspective of easily obtaining an appropriate viscosity for an inkjet ink, the content of inorganic components in the inkjet ink (e.g., the total amount of luminescent nanocrystals and light scattering particles) is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, and even more preferably 40 parts by mass or less, relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins and light scattering particles in the inkjet ink. The content of inorganic components in inkjet ink (e.g., the total amount of luminescent nanocrystals and light scattering particles) relative to the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in inkjet ink (100 parts by mass) can be 5 parts by mass to 80 parts by mass, 10 parts by mass to 50 parts by mass, or 20 parts by mass to 40 parts by mass.

The inkjet ink may contain other components other than the above components within the scope that does not hinder the effect of the present invention. Examples of other components include polymer dispersants, solvents, antioxidants, etc.

[Polymer dispersant]

The polymer dispersant is a polymer compound having a weight average molecular weight of 750 or more and having a functional group having affinity for light scattering particles. The polymer dispersant has the function of dispersing light scattering particles. The polymer dispersant is adsorbed on the light scattering particles through the functional group having affinity for the light scattering particles, and the light scattering particles are dispersed in the inkjet ink by electrostatic repulsion and/or stereo repulsion between the polymer dispersants. The polymer dispersant is preferably bound to the surface of the light scattering particles and adsorbed on the light scattering particles, but it can also be bound to the surface of the luminescent nanocrystals and adsorbed on the luminescent nanocrystals, or it can be free in the inkjet ink.

As functional groups having affinity for light scattering particles, there are acidic functional groups, alkaline functional groups, and non-ionic functional groups. Acidic functional groups have dissociative protons and can be neutralized by bases such as amines and hydroxide ions, while alkaline functional groups can also be neutralized by acids such as organic acids and inorganic acids.

Examples of the acidic functional group include carboxyl (-COOH), sulfonyl (-SO ₃ H), sulfate (-OSO ₃ H), phosphonic acid (-PO(OH) ₃ ), phosphoric acid (-OPO(OH) ₃ ), phosphinic acid (-PO(OH)-), and hydrazine (-SH).

As basic functional groups, primary amine groups, secondary amine groups, tertiary amine groups, ammonium groups, imine groups, and nitrogen-containing heterocyclic groups such as pyridine, pyrimidine, pyrazine, imidazole, and triazole can be cited.

Examples of the nonionic functional group include a hydroxyl group, an ether group, a thioether group, a sulfinyl group (-SO-), a sulfonyl group ( _-SO2- ), a carbonyl group, a formyl group, an ester group, a carbonate group, an amide group, a carbamoyl group, a urea group, a sulfamide group, a thiourea group, an amine sulfonyl group, a cyano group, an alkenyl group, an alkynyl group, a phosphine oxide group, and a phosphine sulfide group.

The polymer dispersant may be a polymer of a single monomer (homopolymer) or a copolymer of multiple monomers (copolymer). Furthermore, the polymer dispersant may be any of a random copolymer, a block copolymer or a graft copolymer. Furthermore, when the polymer dispersant is a graft copolymer, it may be a comb-shaped graft copolymer or a star-shaped graft copolymer. The polymer dispersant may be, for example, an acrylic resin, a polyester resin, a polyurethane resin, a polyamide resin, a polyether, a phenol resin, a silicone resin, a polyurea resin, an amino resin, an epoxy resin, polyamines such as polyethyleneimine and polyallylamine, polyimides, etc.

As a polymer dispersant, commercial products can also be used. As commercial products, Ajisper PB series manufactured by Ajinomoto Fine-Techno Co., Ltd., DISPERBYK series and BYK- series manufactured by BYK, and Efka series manufactured by BASF can be used.

As commercially available polymer dispersants, for example, DISPERBYK-130, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-167, DISPERBYK-168, DISPERBYK-170 manufactured by BYK-Chemie can be used. ", "DISPERBYK-171", "DISPERBYK-174", "DISPERBYK-180", "DISPERBYK-182", "DISPERBYK-183", "DISPERBYK-184", "DISPERBYK-185", "DISPERBYK-2000", "DISPERBYK-2001", "DISPERBYK-2008", "DISPERBYK-2010", "DISPERBYK-2011", "DISPERBYK-2012", "DISPERBYK-2013", "DISPERBYK-2014", "DISPERBYK-2015", "DISPERBYK-2016", "DISPERBYK-2017", "DISPERBYK-2018", "DISPERBYK-2019", "DISPERBYK-2020", "DISPERBYK-2021", "DISPERBYK-2023", "DISPERBYK-2024", "DISPERBYK-2025", "DISPERBYK-2026", "DISPERBYK-2027", "DISPERBYK-2028", "DISPERBYK-2029", "DISPERBYK-2030", "DISPERBYK-2031", "DISPERBYK-2032", "DISPERBYK-2033", "DISPERBYK-2034", "DISPERBYK-2035", "DISPERBYK-2036", "DISPERBYK-2037", "DISPERBYK-2038", "DISPERBYK-2039", "DISPERBYK-2 DISPERBYK-2009", "DISPERBYK-2020", "DISPERBYK-2022", "DISPERBYK-2025", "DISPERBYK-2050", "DISPERBYK-2070", "DISPERBYK-2096", "DISPERBYK-2150", "DISPERBYK-2155", "DISPERBYK-2163", "DISPERBYK-2164", "DISPERBYK-2165", "DISPERBYK-2166", "DISPERBYK-2167", "DISPERBYK-2168", "DISPERBYK-2170", "DISPERBYK-2171", "DISPERBYK-2173", "DISPERBYK-2174", "DISPERBYK-2175", "DISPERBYK-2176", "DISPERBYK-2177", "DISPERBYK-2178", "DISPERBYK-2179", "DISPERBYK-2180", "DISPERBYK-2181", "DISPERBYK-2183", "DISPERBYK-2184", "DISPERBYK-2185", "DISPERBYK-2186", "DISPERBYK-2187", "DISPERBYK-2188", "DISPERBYK-2189", "DISPERBYK-2190", "DISPERBYK-2191", "DISPERBYK-2192", "DISPERBYK-2193", "DISPERBYK-2194", "DISPERBYK-2195", "DISPERB K)-2164", "BYK-LPN21116" and "BYK-LPN6919" manufactured by BASF; "EFKA4010", "EFKA4015", "EFKA4046", "EFKA4047", "EFKA4061", "EFKA4080", "EFKA4300", "EFKA4310", "EFKA4320", "EFKA4330", "EFKA4340", "EFKA4560", "EFKA4585", "EFKA5207", "EFKA1501", "EFKA1502", "EFKA1503" and "EFKA PX-4701; Solsperse 3000, Solsperse 9000, Solsperse 13240, Solsperse 13650, Solsperse 13940, Solsperse 11200, Solsperse 13940, Solsperse 13240, Solsperse 1365 ... Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 20000, Solsperse 21000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 280 00", "Solsperse 32000", "Solsperse 32500", "Solsperse 32550", "Solsperse 32600", "Solsperse 33000", "Solsperse 34750", "Solsperse 35100", "Solsperse 35200", "Solsperse Solsperse 36000, Solsperse 37500, Solsperse 38500, Solsperse 39000, Solsperse 41000, Solsperse 54000, Solsperse 71000 and Solsperse 76500; Ajinomoto Fine Chemicals Fine-Techno Co., Ltd. manufactured "Ajisper PB821", "Ajisper PB822", "Ajisper PB881", "PN411" and "PA111"; Evonik Co., Ltd. manufactured "TEGO Dispers 650", "TEGO Dispers 660C", "TEGO Dispers (Dispers rs)662C", "TEGO Dispers 670", "TEGO Dispers 685", "TEGO Dispers 700", "TEGO Dispers 710" and "TEGO Dispers 760W"; "Disparlon DA-703-50", "DA-705" and "DA-725" manufactured by Kusumoto Chemicals, etc.

[Solvent]

Examples of solvents include ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol dibutyl ether, diethyl adipate, dibutyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, diethyl succinate, 1,4-butanediol diacetate, and glyceryl triacetate.

From the perspective of continuous ejection of the inkjet ink, the boiling point of the solvent under atmospheric pressure is preferably above 150°C, and more preferably above 180°C. Furthermore, when forming a pixel portion, the solvent needs to be removed from the inkjet ink before the inkjet ink hardens, so from the perspective of easy removal of the solvent, the boiling point of the solvent under atmospheric pressure is preferably below 300°C.

In the inkjet ink of this embodiment, the photopolymerizable compound also functions as a dispersant, so that light scattering particles and luminescent nanocrystals can be dispersed without a solvent. In this case, there is an advantage that there is no need to remove the solvent by drying when forming the pixel portion.

[Antioxidant]

The inkjet ink may further contain an antioxidant. In this case, the quantum yield can be improved, and the decrease in quantum yield over time can be further suppressed. The antioxidant may be, for example, a phosphite compound, a thioether compound, etc. From the perspective of improving the quantum yield and further suppressing the decrease in quantum yield over time, a phosphite compound is preferred.

The antioxidant may be a triester phosphite compound. The triester phosphite compound may be a compound represented by the following formula (2).

In formula (2), R ¹¹ , R ¹² and R ¹³ each independently represent a monovalent organic group. Two selected from R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring. The monovalent organic group may be, for example, a monovalent alkyl group. Examples of the monovalent alkyl group include alkyl groups, aryl groups, alkenyl groups, etc. The number of carbon atoms in the monovalent alkyl group may be 1 to 30, or 4 to 18.

Specific examples of the compound represented by formula (2) include triphenyl phosphite (triphenyl phosphite), 2-ethylhexyl diphenyl phosphite, diphenyl octyl phosphite, etc.

The phosphite triester compound can be a liquid or a solid at room temperature (25°C), but it is preferably a liquid at room temperature (25°C) from the viewpoint of fully satisfying the required performance of the inkjet ink, which is compatibility with other components (photopolymerizable compounds, etc.) in the inkjet ink, and further suppressing the decrease in the quantum yield of the inkjet ink. The melting point of the phosphite triester compound can be below 20°C or below 10°C.

From the viewpoint of further suppressing the decrease in the quantum yield of the inkjet ink, the content of the antioxidant may be 0.01 parts by mass or more, 0.1 parts by mass or more, 1 part by mass or more, or 5 parts by mass or more, relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink. Since the decrease in quantum yield can be more effectively suppressed even when added in a small amount, the content of the antioxidant is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, further preferably 5 parts by mass or less, and further preferably 3 parts by mass or less, relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, thermosetting resins, and light scattering particles in the inkjet ink. When the content of the antioxidant is within the above range, in addition to being able to ensure better film strength when the coating film is formed, the permeation of the antioxidant to the surface is further suppressed, and good optical characteristics can be ensured.

When the inkjet ink contains a photopolymerizable compound, from the viewpoint of further suppressing the decrease in the quantum yield of the inkjet ink, the content of the antioxidant can be 0.01 parts by mass or more, 0.1 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, or 3 parts by mass or more relative to 100 parts by mass of the photopolymerizable compound. Since even a small amount of addition can more effectively suppress the decrease in quantum yield, the content of the antioxidant can be 10 parts by mass or less, 7 parts by mass or less, or 5 parts by mass or less relative to 100 parts by mass of the photopolymerizable compound. When the content of the antioxidant is within the above range, in addition to being able to ensure better film strength when the coating film is formed, it also tends to further suppress the permeation of the antioxidant to the surface and to ensure good optical properties.

Regarding the viscosity of the inkjet ink described above at the ink temperature during inkjet printing (e.g., a temperature range of 25°C to 40°C), for example, from the perspective of ejection stability during inkjet printing, it can be 2 mPa.s or more, 5 mPa.s or more, or 7 mPa.s or more. From the perspective of obtaining an inkjet ink suitable for forming a pixel portion, the viscosity of the inkjet ink at the ink temperature during inkjet printing (e.g., a temperature range of 25°C to 40°C) can be 17 mPa.s or less, 15 mPa.s or less, or 12 mPa.s or less. The viscosity of the inkjet ink at the ink temperature during inkjet printing (e.g., a temperature range of 25°C to 40°C) can be, for example, 2 mPa.s to 17 mPa.s, 2 mPa.s or less. s~15mPa．s、2mPa．s~12mPa．s、5mPa．s~17mPa．s、5mPa．s~15mPa．s、5mPa．s~12mPa．s、7mPa．s~17mPa．s、7mPa．s~15mPa．s、or 7mPa．s~12mPa．s. For example, the viscosity of the inkjet ink at 40°C may be within the above range. In this specification, the viscosity of the inkjet ink is, for example, the viscosity measured using an E-type viscometer.

When the viscosity of the inkjet ink at the ink temperature during inkjet printing is above 2mPa.s, the curved liquid surface shape of the inkjet ink at the front end of the ink ejection hole of the printhead is stable, so the ejection control of the inkjet ink (such as the control of the ejection amount and the timing of the ejection) becomes easy. On the other hand, when the viscosity of the inkjet ink at the ink temperature during inkjet printing is below 17mPa.s, the inkjet ink can be ejected smoothly from the ink ejection hole, and the pixel portion can be easily formed.

The surface tension of the inkjet ink is preferably a surface tension suitable for the inkjet method, specifically, preferably in the range of 20mN/m~40mN/m, more preferably 25mN/m ~35mN/m. By setting the surface tension to this range, ejection control (for example, control of ejection amount and ejection timing) becomes easy, and the occurrence of flight bend can be suppressed. In addition, flight bend refers to the deviation of the landing position of the inkjet ink relative to the target position by more than 30μm when the inkjet ink is ejected from the ink ejection hole. When the surface tension is less than 40mN/m, the curved liquid surface shape at the front end of the ink ejection hole is stable, so the ejection control of the inkjet ink (for example, control of ejection amount and ejection timing) becomes easy. On the other hand, when the surface tension is 20mN/m or more, the inkjet ink can be prevented from contaminating the periphery of the ink ejection hole, thereby suppressing the occurrence of flight bending. That is, there will be no situation where the inkjet ink incorrectly lands on the pixel forming area where it should land, resulting in insufficient pixel filling, or the inkjet ink lands on the pixel forming area (or pixel area) adjacent to the pixel forming area where it should land, resulting in reduced color reproducibility. The inkjet ink can have the surface tension at the ink temperature during inkjet printing (e.g., a temperature range of 25°C to 40°C), and can also have the surface tension at 40°C.

The inkjet ink of this embodiment is preferably applied to a piezoelectric jet (Piezojet) inkjet recording device based on a mechanical ejection mechanism using a piezoelectric element. In the piezoelectric jet method, the inkjet ink is not exposed to high temperature instantly during each ejection. Therefore, the luminescent nanocrystals are less likely to deteriorate, and it is easier to obtain the expected luminescent properties in the pixel part (light conversion layer).

From the viewpoint of suppressing the absorption of moisture in the atmosphere by the coating film of the inkjet ink, and suppressing the decrease in the luminescence (e.g., fluorescence) of the luminescent nanoparticles (quantum dots, etc.) over time, in this embodiment, the coating film of the inkjet ink is preferably alkali-insoluble. That is, the inkjet ink of this embodiment is preferably an inkjet ink capable of forming an alkali-insoluble coating film. Such an inkjet ink can be obtained by using an alkali-insoluble photopolymerizable compound and/or an alkali-insoluble thermosetting resin as the photopolymerizable compound and/or the thermosetting resin. The coating film of the inkjet ink is alkali-insoluble, which means that the amount of the coating film of the inkjet ink dissolved in a 1 mass % potassium hydroxide aqueous solution at 25°C is 30 mass % or less based on the total mass of the coating film of the inkjet ink. The dissolution amount of the coating film of the inkjet ink is preferably 10 mass % or less, and more preferably 3 mass % or less. In addition, the content that the inkjet ink is an inkjet ink capable of forming an alkali-insoluble coating film can be confirmed by measuring the dissolution amount of a coating film with a thickness of 1μm obtained by applying the inkjet ink on a substrate and drying it at 80°C for 3 minutes.

<Inkjet ink manufacturing method>

The inkjet ink of the embodiment is obtained, for example, by mixing the constituent components of the inkjet ink and performing a dispersion process.

The method for manufacturing inkjet ink includes, for example, a first step of preparing a dispersion of light scattering particles containing light scattering particles; and a second step of mixing the dispersion of light scattering particles and luminescent nanocrystals. As luminescent nanocrystals, luminescent nanocrystals having organic ligands on their surfaces are used. That is, the luminescent nanocrystal dispersion further contains organic ligands. The dispersion of light scattering particles may also further contain a polymer dispersant. In this method, the dispersion of light scattering particles may further contain a photopolymerizable compound and/or a thermosetting resin, and in the second step, the photopolymerizable compound and/or the thermosetting resin may be further mixed. According to this method, the light scattering particles can be fully dispersed. Therefore, the optical properties of the pixel portion can be improved, and an inkjet ink with excellent ejection stability can be easily obtained.

In the step of preparing a dispersion of light scattering particles, the dispersion of light scattering particles can be prepared by mixing the light scattering particles with a polymer dispersant and a photopolymerizable compound and/or a thermosetting resin as appropriate and performing a dispersion treatment. The mixing and dispersion treatment can be performed using a dispersion device such as a bead mill, a paint conditioner, a planetary mixer, and a spray mill. From the viewpoint that the dispersibility of the self-light scattering particles becomes good and the average particle size of the light scattering particles is easily adjusted to a desired range, it is preferably to use a bead mill or a paint conditioner. By mixing the light scattering particles and the polymer dispersant before mixing the luminescent nanocrystals with the light scattering particles, the light scattering particles can be more fully dispersed. Therefore, it is possible to further easily obtain excellent ejection stability and excellent external quantum efficiency.

The method for manufacturing the inkjet ink may also include, before the second step, a step of preparing a dispersion of luminescent nanocrystals containing luminescent nanocrystals and an organic solvent. In this case, in the second step, a dispersion of light-scattering particles is mixed with a dispersion of luminescent nanocrystals. In the step of preparing a dispersion of luminescent nanocrystals, the luminescent nanocrystal dispersion may be prepared by mixing the luminescent nanocrystals with an organic solvent and performing a dispersion treatment. The mixing and dispersion treatment may be performed using a dispersion device such as a bead mill, a coating conditioner, a planetary mixer, or a jet mill. From the viewpoint that the dispersibility of the self-luminescent nanocrystals becomes good and the average particle size of the luminescent nanocrystals is easily adjusted to the desired range, it is preferable to use a bead mill, a coating regulator or a jet mill. According to this method, the luminescent nanocrystals can be fully dispersed. Therefore, the optical properties of the pixel portion can be improved, and an inkjet ink with excellent ejection stability can be easily obtained. In the above step, a photopolymerizable compound and/or a thermosetting resin can be further contained in the dispersion of the luminescent nanocrystals.

In the manufacturing method, the organic solvent can be prepared in the first step or in the second step. That is, the first step can be a step of preparing a dispersion of light-scattering particles containing light-scattering particles, a polymer dispersant and an organic solvent, and the second step can be a step of mixing the dispersion of light-scattering particles, luminescent nanocrystals and an organic solvent.

The method for manufacturing inkjet ink may further include a step of mixing an organic solvent with a thermosetting resin and/or a photopolymerizable compound to prepare a solution containing the thermosetting resin and/or the photopolymerizable compound. In this case, in the second step, the light scattering particle dispersion, the luminescent nanocrystal dispersion, and the solution containing the thermosetting resin and/or the photopolymerizable compound prepared in the step may be mixed with the organic solvent. That is, the second step may be a step of mixing the light scattering particle dispersion, the luminescent nanocrystal dispersion, the solution containing the thermosetting resin and/or the photopolymerizable compound, and the organic solvent.

In this manufacturing method, other components other than the above components may be further used. In this case, the other components may be contained in the luminescent nanocrystal dispersion or in the light scattering particle dispersion. Furthermore, the other components may be mixed in a composition obtained by mixing the luminescent nanocrystal dispersion and the light scattering particle dispersion.

<Ink jet ink set>

An inkjet ink set of an embodiment includes the inkjet ink of the embodiment. In addition to the inkjet ink (luminescent inkjet ink) of the embodiment, the inkjet ink set may also include an inkjet ink (non-luminescent inkjet ink) that does not contain luminescent nanocrystals. The non-luminescent inkjet ink may be a previously known inkjet ink, which may have the same composition as the inkjet ink (luminescent inkjet ink) of the embodiment except that it does not contain luminescent nanocrystals.

Non-luminescent inkjet ink does not contain luminescent nanocrystals, so when light is incident on a pixel portion formed by non-luminescent inkjet ink (including a pixel portion of a cured product of non-luminescent inkjet ink), the light emitted from the pixel portion has approximately the same wavelength as the incident light. Therefore, non-luminescent inkjet ink can be preferably used to form a pixel portion of the same color as the light from the light source. For example, when the light from the light source is light with a wavelength in the range of 420nm to 480nm (blue light), the pixel portion formed by non-luminescent inkjet ink may become a blue pixel portion.

The non-luminescent inkjet ink preferably contains light scattering particles. When the non-luminescent inkjet ink contains light scattering particles, the light incident on the pixel portion can be scattered by the pixel portion formed by the non-luminescent inkjet ink, thereby reducing the light intensity difference of the outgoing light from the pixel portion in the viewing angle.

<Light conversion layer and color filter, and their manufacturing methods>

Below, the light conversion layer and color filter obtained by using the inkjet ink set of the embodiment are described in detail with reference to the drawings. In addition, in the following description, the same symbols are used for the same or equivalent elements, and repeated descriptions are omitted.

FIG1 is a schematic cross-sectional view of a color filter in an embodiment. As shown in FIG1 , the color filter 100 includes a substrate 40 and a light conversion layer 30 disposed on the substrate 40. The light conversion layer 30 includes a plurality of pixel portions 10 and a light shielding portion 20.

The light conversion layer 30 has a first pixel portion 10a, a second pixel portion 10b, and a third pixel portion 10c as the pixel portion 10. The first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c are arranged in a grid shape in a repeated manner in this order. The light shielding portion 20 is provided between adjacent pixel portions, that is, between the first pixel portion 10a and the second pixel portion 10b, between the second pixel portion 10b and the third pixel portion 10c, and between the third pixel portion 10c and the first pixel portion 10a. In other words, the adjacent pixel portions are separated from each other by the light shielding portion 20.

The first pixel portion 10a and the second pixel portion 10b are respectively luminescent pixel portions (luminescent pixel portions) comprising a cured product of the inkjet ink of the embodiment. The cured product contains luminescent nanocrystals, a curing component and light scattering particles. The curing component is a component obtained by polymerization of a photopolymerizable compound and/or curing (polymerization, crosslinking, etc.) of a thermosetting resin, and includes a polymer of a photopolymerizable compound and/or a cured product of a thermosetting resin. That is, the first pixel portion 10a includes a first curing component 13a and first luminescent nanocrystals 11a and first light scattering particles 12a respectively dispersed in the first curing component 13a. Similarly, the second pixel portion 10b includes a second curing component 13b and second luminescent nanocrystals 11b and second light scattering particles 12b respectively dispersed in the second curing component 13b. 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 particles 12a and the second light scattering particles 12b may be the same or different.

The first luminescent nanocrystal 11a is a red luminescent nanocrystal that absorbs light of a wavelength in the range of 420nm to 480nm and emits light having a peak luminescence wavelength in the range of 605nm to 665nm. That is, the first pixel portion 10a can also be referred to as a red pixel portion for converting blue light into red light. Moreover, the second luminescent nanocrystal 11b is a green luminescent nanocrystal that absorbs light of a wavelength in the range of 420nm to 480nm and emits light having a peak luminescence wavelength in the range of 500nm to 560nm. That is, the second pixel portion 10b can also be referred to as a green pixel portion for converting blue light into green light.

The total content of the luminescent nanocrystals and the organic ligands in the luminescent pixel portion is 21% by mass or more, based on the total mass of the luminescent pixel portion, and may be 25% by mass or more, 27% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, or 50% by mass or more, and may be 70% by mass or less, 65% by mass or less, 60% by mass or less, or 55% by mass or less.

From the perspective of achieving a better external quantum efficiency improvement effect, the content of light scattering particles in the luminescent pixel portion can be 0.1 mass% or more, 1 mass% or more, 3 mass% or more, or 5 mass% or more based on the total mass of the luminescent pixel portion. From the perspective of achieving a better external quantum efficiency improvement effect and excellent reliability of the pixel portion, the content of light scattering particles can be 60 mass% or less, 50 mass% or less, 40 mass% or less, or 30 mass% or less based on the total mass of the luminescent pixel portion.

The third pixel portion 10c is a non-luminescent pixel portion (non-luminescent pixel portion) containing a cured product of the non-luminescent inkjet ink. The cured product does not contain luminescent nanocrystals, but contains light scattering particles and a curing component. The curing component is, for example, a component obtained by polymerization of a photopolymerizable compound and/or curing (polymerization, crosslinking, etc.) of a thermosetting resin, including a polymer of a photopolymerizable compound and/or a cured body of a thermosetting resin. That is, the third pixel portion 10c includes a third curing component 13c and third light scattering particles 12c dispersed in the third curing component 13c. The third light scattering particles 12c may be the same as or different from the first light scattering particles 12a and the second light scattering particles 12b.

The third pixel unit 10c has a transmittance of 30% or more for light with a wavelength in the range of 420nm to 480nm, for example. Therefore, the third pixel unit 10c functions as a blue pixel unit when a light source emitting light with a wavelength in the range of 420nm to 480nm is used. In addition, the transmittance of the third pixel unit 10c can be measured by a microscopic spectrometer.

From the perspective of further reducing the light intensity difference in the viewing angle, the content of light scattering particles in the non-luminescent pixel portion can be 1% by mass or more, 5% by mass or more, or 10% by mass or more, based on the total mass of the non-luminescent pixel portion. From the perspective of further reducing light reflection, the content of light scattering particles can be 80% by mass or less, 75% by mass or less, or 70% by mass or less, based on the total mass of the non-luminescent pixel portion.

The thickness of the pixel portion (the first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c) may be, for example, 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, or 6 μm or more, and may be 30 μm or less or 20 μm or less.

The light shielding portion 20 is a so-called black matrix provided for the purpose of separating adjacent pixel portions to prevent color mixing and 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, a cured product of a resin composition containing light shielding particles such as carbon particles, metal oxides, inorganic pigments, and organic pigments in a binder polymer may also be used. As the binder polymer used here, one or more of polyimide resins, acrylic resins, epoxy resins, polyacrylamide, polyvinyl alcohol, gelatin, casein, cellulose, etc., a mixture of two or more, a photosensitive resin, an oil-in-water (O/W) emulsion type resin composition (for example, a reactive silicone emulsified), etc. can be used. The thickness of the light shielding portion 20 can be, for example, not less than 0.5 μm and not more than 10 μm.

The substrate 40 is a transparent substrate having light transmittance, for example, a transparent glass substrate such as quartz glass, Pyrex (registered trademark) glass, synthetic quartz plate, a transparent resin film, a transparent flexible substrate such as an optical resin film, etc. can be used. Among these, it is preferable to use a glass substrate including an alkali-free glass containing no alkali components in the glass. Specifically, "7059 glass", "1737 glass", "EAGLE 200" and "EAGLE XG" manufactured by Corning, "AN100" manufactured by Asahi Glass Co., Ltd., "OA-10G" and "OA-11" manufactured by Nippon Electric Glass Co., Ltd. are preferred. These are raw materials with a small thermal expansion coefficient, and are excellent in dimensional stability and workability during high-temperature heating treatment.

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

A manufacturing method of a light conversion layer 30 (color filter 100) of an embodiment includes: a step of forming a light shielding portion 20 on a substrate 40 (light shielding portion forming step); a step of configuring the inkjet ink of the embodiment in a pixel forming area divided by the light shielding portion 20 on the substrate 40 by inkjet method (configuration step); and a step of curing the inkjet ink (curing step).

In the light-shielding portion forming step, the light-shielding portion 20 is formed into a pattern (e.g., a grid shape). The method of forming the light-shielding portion 20 includes forming a metal film such as chromium, or a film of a resin composition containing light-shielding particles on one side of the substrate 40, and patterning the film. The metal film can be formed, for example, by a sputtering method, a vacuum evaporation method, etc. The film of a resin composition containing light-shielding particles can be formed, for example, by coating, printing, etc. As a method of patterning, photolithography can be cited.

In the configuration step, inkjet ink is selectively configured (attached) in the pixel forming area (area on the substrate 40 where the light shielding part 20 is not formed (opening of the light shielding part 20)) by inkjet method. As the inkjet method, there can be cited the Bubble Jet (registered trademark) method using an electrothermal converter as an energy generating element, or the piezoelectric jet method using a piezoelectric element, etc.

In the hardening step, the inkjet ink arranged in the arrangement step is hardened by irradiation with active energy rays or heating.

When the inkjet ink is cured by irradiation with active energy rays (e.g., ultraviolet rays), a mercury lamp, a metal halide lamp, a xenon lamp, a light emitting diode (LED), etc. may be used as a light source. The wavelength of the irradiated light may be, for example, greater than 200 nm and less than 440 nm. The exposure amount may be, for example, greater than 10 mJ/ ^cm2 and less than 4000 mJ/ ^cm2 .

When the inkjet ink is hardened by heating, the heating temperature can be, for example, above 110°C and below 250°C. The heating time can be, for example, above 10 minutes and below 120 minutes.

When the inkjet ink contains a solvent (organic solvent), the manufacturing method of this embodiment may further include a step of volatilizing the solvent (volatilization step). The volatilization step is performed, for example, between the configuration step and the curing step. In the volatilization step, the solvent is volatilized, for example, by heating the inkjet ink. The heating temperature may be, for example, above 50°C and below 150°C. The heating time may be, for example, above 1 minute or above 3 minutes and below 30 minutes.

In the volatilization step, the solvent (organic solvent) can also be volatilized by drying based on reduced pressure (reduced pressure drying). From the perspective of controlling the composition of the ink composition, the conditions for reduced pressure drying can generally be 1.0Pa~500Pa, 20℃~30℃, 3 minutes~30 minutes.

Above, an embodiment of the color filter and the light conversion layer and the manufacturing method thereof is described, but the present invention is not limited to the embodiment.

For example, instead of the third pixel portion 10c or in addition to the third pixel portion 10c, the light conversion layer may also include: a pixel portion (blue pixel portion) containing a cured product of a luminescent inkjet ink containing blue luminescent nanocrystals. Moreover, the light conversion layer may include: a pixel portion (e.g., a yellow pixel portion) containing a cured product of a luminescent inkjet ink containing nanocrystals emitting light of other colors than red, green, and blue. In these cases, it is preferred that the luminescent nanocrystals contained in each pixel portion of the light conversion layer have absorption maximum wavelengths in the same wavelength region.

Furthermore, at least a portion of the pixel portion of the light conversion layer may include a cured product of a composition containing a pigment other than the luminescent nanocrystals.

Furthermore, the color filter may include an ink-repellent layer containing a material having ink repellency and having a width smaller than that of the light-shielding portion on the pattern of the light-shielding portion. Furthermore, instead of providing the ink-repellent layer, a photosensitive medium containing layer as a wettability variable layer may be formed in the area including the pixel forming area in a coating manner over the entire surface, and then the photosensitive medium containing layer is exposed to light through a photomask to selectively increase the ink affinity of the pixel forming area. Examples of the photosensitive medium include titanium oxide, zinc oxide, and the like.

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

Furthermore, the color filter may include a protective layer on the pixel portion. The protective layer is provided to flatten the color filter and prevent the components contained in the pixel portion, or the components contained in the pixel portion and the photocatalyst containing layer from eluting into the liquid crystal layer. The material constituting the protective layer may be used as a known protective layer for color filters.

Furthermore, in addition to the luminescent nanocrystals, the pixel portion of the light conversion layer of this embodiment may further contain a pigment having a color substantially the same as the luminescent color of the luminescent nanocrystals. In order to make the pixel portion contain the pigment, the inkjet ink may contain the pigment.

Furthermore, one or two of the red pixel portion (R), the green pixel portion (G), and the blue pixel portion (B) in the light conversion layer of the present embodiment may be formed as a pixel portion containing no luminescent nanocrystals but containing a colorant. As the colorant that can be used here, a known colorant can be used. For example, as a colorant for the red pixel portion (R), a diketopyrrolopyrrole pigment and/or anionic red organic dye can be listed. As a colorant for the green pixel portion (G), at least one selected from the group consisting of a mixture of a copper halogenide phthalocyanine pigment, a phthalocyanine green dye, a phthalocyanine blue dye, and an azo yellow organic dye can be listed. As color materials for the blue pixel part (B), ε-type copper phthalocyanine pigments and/or cationic blue organic dyes can be listed. The amount of these color materials used, when contained in the light conversion layer, is preferably 1% to 5% by mass based on the total mass of the pixel part (cured product of inkjet ink) from the perspective of preventing a decrease in transmittance.

Embodiment

The present invention is specifically described below by way of examples. However, the present invention is not limited to the following examples. In addition, all materials used in the examples are obtained by introducing argon and replacing dissolved oxygen with argon. Titanium oxide was heated at 175°C for 4 hours under a reduced pressure of 1 mmHg before mixing, and then placed in an argon gas environment for cooling. The liquid materials used in the examples were dehydrated for more than 48 hours using a molecular sieve 3A before mixing.

[Preparation of organic ligands for InP/ZnSeS/ZnS nanocrystals]

After polyethylene glycol |average Mn400| (|average Mn400|) (manufactured by Sigma-Aldrich) was placed in a flask, succinic anhydride (manufactured by Sigma-Aldrich) in an amount equal to the molar amount of polyethylene glycol |average Mn400| was added thereto while stirring in a nitrogen atmosphere. The internal temperature of the flask was raised to 80°C and stirred for 8 hours to obtain an organic ligand 1 represented by the following formula (A-1) as a light yellow viscous oil.

After polyethylene glycol |average Mn750| (manufactured by Sigma-Aldrich) was placed in a flask, succinic anhydride (manufactured by Sigma-Aldrich) in an amount equal to the molar amount of polyethylene glycol |average Mn750| was added thereto while stirring in a nitrogen atmosphere. The internal temperature of the flask was raised to 80°C and stirred for 8 hours to obtain an organic ligand 2 represented by the following formula (A-2) as a light yellow viscous oil.

With reference to Japanese Patent Publication No. 2002-121549, an organic ligand 3 represented by the following formula (A-3) (triethylene glycol monomethyl ether ester of 3-butylpropionic acid (triethylene glycol monomethyl ether butylpropionate, TEGMEMP)) was synthesized.

After JEFAMINE M-1000 (manufactured by Huntsman) was placed in a flask, succinic anhydride (manufactured by Sigma-Aldrich) in an amount equal to that of JEFAMINE M-1000 was added thereto while stirring in a nitrogen atmosphere. The internal temperature of the flask was raised to 80°C and stirred for 8 hours to obtain the comparative ligand 1 represented by the following formula (B) as a light yellow viscous oil.

The polystyrene-equivalent weight average molecular weight (Mw) of the ligands was measured by GPC measurement using HLC-8320 manufactured by Tosoh. As a result, the Mw of organic ligand 1 was 597, the Mw of organic ligand 2 was 906, the Mw of organic ligand 3 was 273, and the Mw of comparative example ligand 1 was 1191.

<Preparation of red luminescent InP/ZnSeS/ZnS nanocrystal dispersion >

[Preparation of indium laurate solution]

Add 10 g of 1-octadecene (ODE), 146 mg (0.5 mmol) of indium acetate, and 300 mg (1.5 mmol) of lauric acid to a reaction flask to obtain a mixture. Heat the mixture at 140°C for 2 hours under vacuum to obtain a transparent solution (indium laurate solution). Keep the solution at room temperature in a glove box until needed. In addition, since indium laurate has low solubility at room temperature and is easily precipitated, when using the indium laurate solution, heat the indium laurate precipitated in the solution (ODE mixture) to about 90°C to form a transparent solution, and then measure the required amount for use.

[Preparation of red luminescent nanocrystal core (InP core)]

5 g of trioctylphosphine oxide (TOPO), 1.46 g (5 mmol) of indium acetate and 3.16 g (15.8 mmol) of lauric acid were added to a reaction flask to obtain a mixture. The mixture was heated at 160°C for 40 minutes under a nitrogen (N ₂ ) environment, and then heated at 250°C for 20 minutes under vacuum. Next, the reaction temperature (temperature of the mixture) was raised to 300°C under a nitrogen (N ₂ ) environment. At this temperature, a mixture of 3 g of 1-octadecene (ODE) and 0.25 g (1 mmol) of tri(trimethylsilyl)phosphine was quickly introduced into the reaction flask, and the reaction temperature was maintained at 260°C. After 5 minutes, the reaction was stopped by removing the heater, and the obtained reaction solution was cooled to room temperature. Next, 8 ml of toluene and 20 ml of ethanol were added to the reaction solution in the glove box. Centrifugal separation was then performed to precipitate the InP nanocrystals, and the InP nanocrystals were obtained by decanting the supernatant. Next, the obtained InP nanocrystals were dispersed in hexane. Thus, a dispersion containing 5% by mass of InP nanocrystals (hexane dispersion) was obtained.

The obtained hexane dispersion of InP nanoparticles and the indium laurate solution were charged into a reaction flask to obtain a mixture. The loading amounts of the hexane dispersion of InP nanoparticles and the indium laurate solution were adjusted to 0.5 g (25 mg of InP nanoparticles) and 5 g (178 mg of indium laurate), respectively. The mixture was allowed to stand at room temperature under vacuum for 10 minutes, and then the flask was restored to normal pressure using nitrogen, and the temperature of the mixture was raised to 230°C, and maintained at this temperature for 2 hours, and the hexane was removed from the inside of the flask. Next, the temperature inside the flask was raised to 250°C, and a mixture of 3 g of 1-octadecene (ODE) and 0.03 g (0.125 mmol) of tri(trimethylsilyl)phosphine was quickly introduced into the reaction flask, and the reaction temperature was maintained at 230°C. After 5 minutes, the reaction was stopped by removing the heater, and the obtained reaction solution was cooled to room temperature. Next, 8 ml of toluene and 20 ml of ethanol were added to the reaction solution in the glove box. Centrifugal separation was then performed to precipitate InP nanoparticles (InP cores) that became the cores of red luminescent InP/ZnSeS/ZnS nanoparticles, and then InP nanoparticles (InP cores) were obtained by decanting the supernatant. Next, the obtained InP nanoparticles (InP cores) are dispersed in hexane to obtain a dispersion (hexane dispersion) containing 5% by mass of InP nanoparticles (InP cores).

[Formation of the shell of red luminescent nanocrystals (ZnSeS/ZnS shell)]

After adding 2.5 g of the obtained InP nanoparticles (InP cores) in hexane dispersion to the reaction flask, 0.7 g of oleic acid was added to the reaction flask at room temperature, and the temperature was raised to 80°C and maintained for 2 hours. Then, 14 mg of diethylzinc, 8 mg of bis(trimethylsilyl) selenide and 7 mg of hexamethyldisilathiane (ZnSeS precursor solution) dissolved in 1 ml of ODE were added dropwise to the reaction mixture, and the temperature was raised to 200°C and maintained for 10 minutes to form a ZnSeS shell with a thickness of 0.5 monolayer.

Then, the temperature was raised to 140°C and maintained for 30 minutes. Next, a ZnS precursor solution obtained by dissolving 69 mg of diethylzinc and 66 mg of hexamethyldisilasulfane in 2 ml of ODE was added dropwise to the reaction mixture, and the temperature was raised to 200°C and maintained for 30 minutes to form a ZnS shell with a thickness of 2 monolayers. After 10 minutes of dropping the ZnS precursor solution, the reaction was stopped by removing the heater. Then, the reaction mixture was cooled to room temperature, and the obtained white precipitate was removed by centrifugal separation to obtain a transparent nanoparticle dispersion (ODE dispersion of InP/ZnSeS/ZnS nanoparticles) in which red luminescent InP/ZnSeS/ZnS nanoparticles were dispersed.

<Preparation of green luminescent InP/ZnSeS/ZnS nanocrystal dispersion>

[Synthesis of green luminescent nanocrystal core (InP core)]

5 g of trioctylphosphine oxide (TOPO), 1.46 g (5 mmol) of indium acetate and 3.16 g (15.8 mmol) of lauric acid were added to a reaction flask to obtain a mixture. The mixture was heated at 160°C for 40 minutes under a nitrogen (N ₂ ) environment, and then heated at 250°C for 20 minutes under vacuum. Next, the reaction temperature (temperature of the mixture) was raised to 300°C under a nitrogen (N ₂ ) environment. At this temperature, a mixture of 3 g of 1-octadecene (ODE) and 0.25 g (1 mmol) of tri(trimethylsilyl)phosphine was quickly introduced into the reaction flask, and the reaction temperature was maintained at 260°C. After 5 minutes, the reaction was stopped by removing the heater, and the obtained reaction solution was cooled to room temperature. Next, 8 ml of toluene and 20 ml of ethanol were added to the reaction solution in the glove box. Centrifugal separation was then performed to precipitate the InP nanocrystals (InP cores), and the InP nanocrystals (InP cores) were obtained by decanting the supernatant. Next, the obtained InP nanocrystals (InP cores) were dispersed in hexane to obtain a dispersion (hexane dispersion) containing 5% by mass of InP nanocrystals (InP cores).

[Synthesis of green luminescent nanocrystal shell (ZnSeS/ZnS shell)]

After adding 2.5 g of the obtained InP nanoparticles (InP cores) in hexane dispersion to the reaction flask, 0.7 g of oleic acid was added to the reaction flask at room temperature and the temperature was raised to 80°C. Then, 14 mg of diethylzinc, 8 mg of bis(trimethylsilyl) selenide and 7 mg of hexamethyldisilasulfane (ZnSeS precursor solution) dissolved in 1 ml of ODE were added dropwise to the reaction mixture to form a ZnSeS shell with a thickness of 0.5 monolayer.

After the ZnSeS precursor solution was added dropwise, the reaction temperature was maintained at 80°C for 10 minutes. Then, the temperature was raised to 140°C and maintained for 30 minutes. Next, a ZnS precursor solution obtained by dissolving 69 mg of diethylzinc and 66 mg of hexamethyldisilasulfane in 2 ml of ODE was added dropwise to the reaction mixture to form a ZnS shell with a thickness of 2 monolayers. After 10 minutes of adding the ZnS precursor solution, the reaction was stopped by removing the heater. Then, the reaction mixture was cooled to room temperature, and the obtained white precipitate was removed by centrifugal separation to obtain a transparent nanoparticle dispersion (ODE dispersion) in which green luminescent InP/ZnSeS/ZnS nanoparticles were dispersed.

[Preparation of green luminescent nanocrystal dispersion 1 (InP/ZnSeS/ZnS nanocrystal dispersion) based on ligand exchange]

To the obtained green luminescent nanocrystal dispersion (ODE dispersion of InP/ZnSeS/ZnS nanocrystal), 2 times the amount of PGMEA (propylene glycol monomethyl ether) was added to temporarily condense the nanocrystals, and then 20 parts by weight of organic ligand 1 was added relative to 100 parts by weight of the total content of the luminescent nanocrystals in the dispersion and the ligands during synthesis (solid components in the ODE dispersion), and then stirred at 80°C for 2 hours to perform ligand exchange. Before the ligand exchange, the condensed nanocrystals were dispersed again while the ligand exchange was taking place. Then, 4 times the amount of heptane was added to the nanocrystal dispersion after the ligand exchange, so that the nanocrystals were condensed again, and after precipitation by centrifugal separation, the supernatant was decanted and dried under vacuum to obtain nanocrystals (InP/ZnSeS/ZnS nanocrystals modified with the organic ligand).

The weight loss of the dried nanocrystals at 150°C to 500°C was measured using TG/DTA6200 manufactured by Hitachi High-Tech Science, and the organic ligand ratio in the luminescent nanocrystals (the content of organic ligands relative to 100 parts by mass of the total content of luminescent nanocrystals and organic ligands) was calculated. The result was 26 parts by mass.

The obtained nanocrystals (InP/ZnSeS/ZnS nanocrystals modified with the organic ligands) are dispersed in 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name: NK Ester A-HD-N, hereinafter also referred to as "HDDA") to obtain a green luminescent nanocrystal dispersion 1. The total content of luminescent nanocrystals and organic ligands in the green luminescent nanocrystal dispersion is 50 mass %.

[Preparation of InP/ZnSeS/ZnS nanocrystal dispersion 2~InP/ZnSeS/ZnS nanocrystal dispersion 5 based on ligand exchange]

By the same method as the InP/ZnSeS/ZnS nanocrystal dispersion 1, the type of organic ligand and the ratio of organic ligand used are adjusted as shown in Table 1, thereby obtaining luminescent nanocrystal dispersions 2 to luminescent nanocrystal dispersions 5. The amount of organic ligand added during ligand exchange relative to the total content of luminescent nanocrystals and ligands during synthesis is 100 parts by mass. In luminescent nanocrystal dispersion 2, it is 50 parts by mass, in luminescent nanocrystal dispersion 3, it is 30 parts by mass, in luminescent nanocrystal dispersion 4, it is 20 parts by mass, in luminescent nanocrystal dispersion 5, it is 30 parts by mass, in luminescent nanocrystal dispersion 6, it is 30 parts by mass, and in luminescent nanocrystal dispersion 7, it is 30 parts by mass.

<Preparation of light-scattering particle dispersion>

In a container filled with argon, 27.5 g of titanium oxide (trade name: CR-60-2, manufactured by Ishihara Sangyo Co., Ltd., average particle size (volume average diameter): 210 nm), 1.0 g of a polymer dispersant (trade name: Ajisper PB-821, manufactured by Ajinomoto Fine-Techno Co., Ltd.), and 21.5 g of HDDA as a light scattering particle dispersant were mixed, and zirconia beads (diameter: 1.25 mm) were added to the obtained mixture. The mixture was dispersed by shaking for 2 hours using a paint conditioner, and the zirconia beads were removed using a polyester mesh filter to obtain a light scattering particle dispersion 1 (titanium oxide content: 55 mass %).

[Preparation of inkjet ink]

<Implementation Example 1>

7.0 g of luminescent nanocrystal dispersion 1, 0.9 g of light scattering particle dispersion 1, 0.3 g of photopolymerization initiator (phenyl (2,4,6-trimethylbenzyl-diphenyl)-phosphine oxide (manufactured by IGM resin, trade name: Omnirad TPO)), 0.3 g of antioxidant Adekastab C and 1.5 g of HDDA were uniformly mixed in a container filled with argon, and the mixture was filtered using a 5 μm filter in a glove box. Further, argon was introduced into the container containing the obtained filtrate, and the container was saturated with argon. Next, the pressure is reduced to remove the argon, thereby obtaining the inkjet ink of Example 1. The total content (non-volatile component concentration) of the luminescent nanocrystals, organic ligands, photopolymerizable compounds and light scattering particles in the inkjet ink based on the total mass of the inkjet ink, and the total content of the luminescent nanocrystals and organic ligands relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds and light scattering particles in the inkjet ink are shown in Table 2.

<Example 2~Example 5, Comparative Example 1~Comparative Example 2, Reference Example 1~Reference Example 2>

The total content (non-volatile component concentration) of luminescent nanocrystals, organic ligands, photopolymerizable compounds and light scattering particles in the inkjet ink based on the total mass of the inkjet ink, and the total content of luminescent nanocrystals and organic ligands relative to 100 parts by mass of the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds and light scattering particles in the inkjet ink were adjusted to the amounts shown in Table 2, and inkjet inks of Examples 2 to 5, Comparative Examples 1 to 2, and Reference Examples 1 to 2 were obtained. Regarding Reference Example 2, diethylene glycol diethyl ether was used as a solvent to adjust the total content of luminescent nanocrystals, organic ligands, photopolymerizable compounds and light scattering particles in the inkjet ink to 25% by mass.

[Evaluation of inkjet ink viscosity and viscosity increase in atmospheric gas environment]

The viscosity of the inkjet ink of the embodiment and the comparative example was evaluated by measuring the viscosity at 40°C using an E-type viscometer. In the viscosity evaluation, when the viscosity at 40°C is 17.0 mPa.s or less, it is evaluated as having a viscosity suitable for forming a pixel portion, and when the viscosity at 40°C exceeds 17.0 mPa.s, it is evaluated as not having a viscosity suitable for forming a pixel portion.

The evaluation of viscosity increase in an atmospheric gas environment (viscosity increase under atmospheric exposure) was carried out by dropping a certain amount of inkjet ink of the embodiment and comparative example into a culture dish and tilting the culture dish after 3 minutes. When the culture dish was tilted, if it flowed without any problem, it was evaluated as no viscosity increase, and if it did not flow or even partially changed into a gel state, it was evaluated as viscosity increase. The evaluation of viscosity increase was carried out in a clean room with a constant humidity (humidity 50±2%RH).

[Evaluation of optical properties]

[Production of samples for evaluation]

Each inkjet ink was applied to a glass substrate in the atmosphere using a spin coater so that the film thickness was 10 μm. In a nitrogen gas environment, the coated film was irradiated with UV so that the accumulated light amount reached 1500 mJ/cm ² using a UV irradiation device using an LED lamp with a main wavelength of 395 nm to cure it, and a layer (light conversion layer) containing a cured product of the inkjet ink was formed on the glass substrate. In this way, a substrate having a light conversion layer, i.e., each evaluation sample, was prepared.

[External quantum efficiency (EQE) evaluation]

As a surface-emitting light source, a blue LED (peak emission wavelength: 450nm) manufactured by CCS Co., Ltd. was used. The measuring device was a radiation spectrophotometer (trade name "MCPD-9800") manufactured by Otsuka Electronics Co., Ltd. connected to an integrating sphere, and the integrating sphere was set on the upper side of the blue LED. The prepared evaluation sample was inserted between the blue LED and the integrating sphere, and the spectrum observed by lighting the blue LED and the illuminance at each wavelength were measured.

Based on the spectrum and illuminance measured by the measuring device, the external quantum efficiency is calculated as follows. The external quantum efficiency is a value indicating the proportion of light (photons) incident on the light conversion layer that is emitted to the observer side as fluorescence. Therefore, the larger the value, the better the luminescence characteristics of the light conversion layer, and it is an important evaluation indicator.

EQE(%)=P1(green)/E(blue)×100

Here, E (blue) and P1 (green) represent the following respectively.

E (blue): Indicates the total value of "illuminance × wavelength ÷hc" in the wavelength range of 380nm~490nm.

P1 (green): Indicates the total value of "illuminance × wavelength ÷ hc" in the wavelength range of 500nm~650nm.

These are values equivalent to the number of observed photons. In addition, h represents Planck’s constant and c represents the speed of light.

[Production of light conversion layer based on inkjet method]

After sputtering metallic chromium on a glass substrate containing alkali-free glass ("OA-10G" manufactured by Nippon Electric Glass Co., Ltd.), a pattern is formed by photolithography, and then a photoresist SU-8 (manufactured by Nippon Kayaku Co., Ltd.) is applied, exposed, developed, and post-baked to form an SU-8 pattern on the chromium pattern. The partition wall pattern thus produced is designed to have an opening portion of a sub-pixel equivalent to 100μm×300μm, with a line width of 20μm and a thickness of 10μm.

An inkjet printer (manufactured by FUJIFILM Dimatix, trade name "DMP-2850") was used to set the head temperature to 40°C, and the inkjet ink was ejected to the opening of the partition wall pattern. For the compositions other than Reference Example 2, after ejection once, they were cured in a nitrogen atmosphere using a UV irradiation device with a main wavelength of 395 nm LED lamp at a cumulative light amount of 1500 mJ/ ^cm2 , thereby producing a 10 μm thick light conversion layer.

After the composition of Reference Example 2 is sprayed into the partition wall opening, the solvent is removed by decompression, and the ink is sprayed into the partition wall pattern again by inkjet. This is repeated 5 times to produce a 10μm thick light conversion layer.

The results of the above evaluations and the number of times the inkjet was ejected during the preparation of the light conversion layer are shown in Table 2. In addition, in Table 2, the content X represents the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, and light scattering particles based on the total mass of the inkjet ink, and the content Y represents the total content of the luminescent nanocrystals and organic ligands relative to 100 parts by mass of the total content of the luminescent nanocrystals, organic ligands, photopolymerizable compounds, and light scattering particles.

10: Pixel section

10a: First pixel portion

10b: Second pixel portion

10c: Third pixel unit

11a: The first luminescent nanocrystal

11b: Second luminescent nanocrystals

12a: First light scattering particles

12b: Second light scattering particles

12c: Third light scattering particles

13a: First hardening component

13b: Second hardening component

13c: Third hardening component

20: Light shielding part

30: Light conversion layer

40: Base material

100: Color filter

Claims (7)

A color filter inkjet ink comprising luminescent nanocrystals, a photopolymerizable compound and/or a thermosetting resin, and light scattering particles, wherein the luminescent nanocrystals have organic ligands on their surfaces, the total content of the luminescent nanocrystals, the organic ligands, the photopolymerizable compound, the thermosetting resin, and the light scattering particles is 41% by mass or more based on the total mass of the inkjet ink, and the luminescent nanocrystals have organic ligands on their surfaces. The total content of the particles and the organic ligand is 21 parts by mass or more relative to 100 parts by mass of the total content of the luminescent nanocrystals, the organic ligand, the photopolymerizable compound, the thermosetting resin and the light scattering particles. The content of the organic ligand is 20 parts by mass or more relative to 100 parts by mass of the total content of the luminescent nanocrystals and the organic ligand. The weight average molecular weight of the organic ligand is 1000 or less. The inkjet ink for color filter as described in claim 1, wherein the total content of the luminescent nanoparticles, the organic ligand, the photopolymerizable compound, the thermosetting resin and the light scattering particles is 70% by mass or more based on the total mass of the inkjet ink. In the inkjet ink for color filter as described in claim 1 or claim 2, the organic ligand comprises a polyoxyalkylene group. A light conversion layer includes a plurality of pixel portions and a light shielding portion disposed between the plurality of pixel portions, wherein the plurality of pixel portions have a luminescent pixel portion comprising a cured product of the inkjet ink for a color filter as described in any one of claims 1 to 3. The light conversion layer as described in claim 4, wherein the light-emitting pixel portion includes: a first light-emitting pixel portion, comprising light-emitting nanocrystals that absorb light with a wavelength in the range of 420 nm to 480 nm and emit light with a peak emission wavelength in the range of 605 nm to 665 nm; and a second light-emitting pixel portion, comprising light-emitting nanocrystals that absorb light with a wavelength in the range of 420 nm to 480 nm and emit light with a peak emission wavelength in the range of 500 nm to 560 nm. The light conversion layer as described in claim 4 or claim 5 further includes a non-luminescent pixel portion containing light scattering particles. A color filter comprises a light conversion layer as described in any one of claims 4 to 6.

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