TW202202581A - Method for printing ink composition for formation of light conversion layer, method for forming light conversion layer and cleaning liquid - Google Patents

Abstract

The present invention suppresses the occurrence of thickness unevenness of a light conversion layer, which is likely to occur after cleaning of a head or a nozzle, in cases where an ink composition for the formation of a light conversion layer is printed by an inkjet method, said ink composition containing luminescent nanocrystal particles and a photopolymerizable compound. A method for printing an ink composition for the formation of a light conversion layer by an inkjet method, said ink composition containing luminescent nanocrystal particles and a photopolymerizable compound. This printing method comprises: a step for cleaning an inkjet head with a cleaning liquid after ejection of the ink composition; and a step for ejecting the ink composition from the inkjet head after the cleaning step. With respect to this printing method, the cleaning liquid contains 80% by mass or more of a low-molecular weight compound; the cleaning liquid has a viscosity of 50 mPa·s or less at 25 DEG C; the low-molecular weight compound has a vapor pressure of 650 Pa or less at 25 DEG C; and the low-molecular weight compound has a logP of from -1 to 8.

Description

Printing method of ink composition for light conversion layer formation, light conversion layer formation method, and cleaning solution

The present invention relates to a printing method of an ink composition for forming a light conversion layer, a method of forming a light conversion layer, and a cleaning solution.

Conventionally, as a pixel portion (color filter pixel portion) in a display such as a liquid crystal display device, a curable resist material containing, for example, red organic pigment particles or green organic pigment particles, and an alkali-soluble resin and/or an acrylic monomer has been used. , manufactured by photolithography.

In recent years, there has been a strong demand for lower power consumption in displays, and studies are being conducted to use luminescent nanocrystals such as quantum dots, quantum rods, and other inorganic phosphor particles to replace the red organic pigment particles or green organic A method of forming color filter pixel portions such as red pixels and green pixels by using pigment particles.

However, in the method of manufacturing a color filter using the above-mentioned photolithography method, due to the characteristics of the manufacturing method, there is a waste of resist materials other than the pixel portion containing the relatively expensive luminescent nanochips shortcomings. Under such circumstances, in order to eliminate the waste of the resist material as described above, the formation of the pixel portion of the light conversion substrate by the ink jet method has been studied (Patent Document 1). [Prior Art Literature] [Patent Literature]

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

[The problem to be solved by the invention]

In the ink jet method, tiny droplets of the ink composition are attached to the printing substrate to form a specific pattern. Light conversion layers such as color filter pixel portions have thin films and fine shapes. Therefore, when applying the ink jet method (ink jet method) to the formation of light conversion layers using luminescent nanocrystals, it is important to discharge straight lines. Good ejection performance (ejection reliability) such as properties, sprayability, and long-term ejection stability.

Therefore, in the case of printing an ink composition containing luminescent nanocrystals and a photopolymerizable compound by an inkjet method, when the ink composition (or a part of the ink composition) adheres to the inkjet head When the discharge failure occurs due to the flow path or the vicinity of the nozzle, etc., the head or nozzle is usually cleaned with a cleaning liquid. However, if the cleaning is not sufficient, the removal of adhering substances in the flow path of the head or the vicinity of the nozzle is not sufficient, or the ink composition is likely to emit light due to the contact between the cleaning liquid and the ink composition. As a result, the thickness of the light conversion layer, which is a printed matter, may vary after cleaning.

Therefore, the problem to be solved by the present invention is: in the case of printing an ink composition for forming a light conversion layer containing luminescent nanocrystals and a photopolymerizable compound by an inkjet method, it is possible to suppress the problem of cleaning the head or Occurrence of thickness variation of the light conversion layer easily generated after the nozzle. [Technical means to solve the problem]

The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, they have found that, when the inkjet head is cleaned with a cleaning solution, a conventional cleaning solution for inkjet ink is used as a solution containing luminescent nanometers. In the case of a cleaning solution for an ink composition for forming a light conversion layer of crystal grains and photopolymerizable compounds, the concentration of each component in the ink composition changes significantly during cleaning, and the dispersed state of the components in the ink composition is destroyed to cause aggregation. substances (such as aggregates of luminescent nanocrystals). Furthermore, the present inventors found that, by using a low molecular weight compound containing 80% by mass or more of a vapor pressure at 25°C of 650 Pa or less and logP of -1 to 8, the viscosity at 25°C of a low molecular weight compound of 50 mPa· The specific liquid material below s can be used as a cleaning liquid to suppress the generation of the above-mentioned aggregates and to remove the above-mentioned ink composition satisfactorily, thereby completing the present invention.

One aspect of the present invention relates to a printing method, which is a method of printing an ink composition for forming a light conversion layer using an inkjet method, wherein the ink composition for forming a light conversion layer contains luminescent nanocrystals and light A polymerizable compound, and the above-mentioned printing method includes the following steps: a step of cleaning the ink jet head after the ink composition is ejected with a cleaning solution; and after the step, the ink composition is ejected from the ink jet head; and the above cleaning solution contains 80% by mass or more of low molecular weight compounds; the viscosity of the cleaning solution at 25°C is 50 mPa·s or less, the vapor pressure of the low molecular weight compounds at 25°C is 650 Pa or less, and the above low molecular weight compounds are The logP of the molecular compound is -1 to 8.

In the printing method of the above aspect, it is possible to suppress the occurrence of thickness variation of the light conversion layer that occurs when the ink composition for forming a light conversion layer containing luminescent nanocrystals and a photopolymerizable compound is printed by an inkjet method. .

The content of the luminescent nanocrystals in the ink composition is preferably 20% by mass or more based on the total mass of the ink composition.

The surface tension of the cleaning solution at 25°C is preferably 50 mN/m or less.

The dissolved oxygen concentration of the cleaning solution is preferably 7 mass ppm or less.

It is preferable that the water content contained in the said cleaning liquid is 6000 mass ppm or less.

The vapor pressure of the above-mentioned low molecular compound at 25°C is preferably 500 Pa or less, more preferably 400 Pa or less.

It is preferable that logP of the said low molecular weight compound is 1-5.

The PII value of the above-mentioned low molecular compound is preferably less than 3.

It is preferable that the said cleaning liquid further contains a dispersing agent.

It is preferable that the said cleaning liquid does not contain a peroxide substantially.

It is preferable that the said cleaning liquid further contains a surface conditioner.

The above-mentioned ink composition preferably further contains light-scattering particles and a polymer dispersant.

Another aspect of the present invention relates to a method for forming a light conversion layer, which is a method for forming a light conversion layer of a cured product containing an ink composition, and includes the steps of: printing by the printing method of the above aspect a step of ink composition; and a step of hardening the ink composition by irradiating the obtained printed matter with light. By this method, a light conversion layer with less thickness variation can be obtained.

Still another aspect of the present invention relates to a cleaning solution for cleaning an inkjet head after ejecting an ink composition for forming a light conversion layer containing luminescent nanocrystals and a photopolymerizable compound, wherein the above The cleaning solution contains 80% by mass or more of low molecular weight compounds, the viscosity at 25°C is 50 mPa·s or less, and the vapor pressure of the above low molecular weight compounds at 25°C is 650 Pa or less, and the logP of the above low molecular weight compounds is -1 ~8. With the cleaning solution, the ink composition for forming a light conversion layer containing the luminescent nanocrystal particles and the photopolymerizable compound, and the adhering matter derived from the ink composition can be removed favorably. [Effect of invention]

According to the present invention, when an ink composition for forming a light conversion layer containing luminescent nanocrystals and a photopolymerizable compound is printed by an inkjet method, light that is easily generated after cleaning the head or nozzle can be suppressed The occurrence of changes in the thickness of the conversion layer.

Hereinafter, embodiments of the present invention will be described in detail. In addition, in this specification, the numerical range represented using "-" means the range which includes the numerical value described before and after "-" as a minimum value and a maximum value, respectively. In addition, in this specification, "hardening of the ink composition" refers to curing the curable components in the ink composition (when the ink composition contains a solvent, the ink composition after drying) (for example, polymerizing a photopolymerizable compound) ) and the recipient. The cured product of the dried ink composition may not contain solvent. Unless otherwise specified, the materials exemplified in this specification may be used alone or in combination of two or more.

＜Printing method＞ A printing method according to one embodiment is a printing method of an ink composition for forming a light conversion layer including luminescent nanocrystals and a photopolymerizable compound, and includes the following steps: after the ink composition is ejected with a cleaning solution The step of cleaning the inkjet head (cleaning step); and the step of ejecting the ink composition from the inkjet head after the cleaning step (discharging step). The cleaning solution used in the printing method is characterized in that it contains 80% by mass or more of low molecular weight compounds, the viscosity of the cleaning solution at 25°C is 50 mPa·s or less, and the vapor pressure of the low molecular weight compounds at 25°C is It is 650 Pa or less, and the logP of the said low molecular weight compound is -1-8. The printing method of one embodiment may further include a step of discharging the ink composition from the ink jet head (discharging step) before the cleaning step. Hereinafter, the ejection step before the cleaning step is referred to as a first ejection step, and the ejection step after the cleaning step is referred to as a second ejection step.

By this printing method, the ink composition (the ink composition for forming a light conversion layer containing the luminescent nanocrystals and the photopolymerizable compound) remaining in the flow path of the ink jet head and the vicinity of the nozzle, and the ink composition derived from the ink composition The adhering matter is well removed by the cleaning step, and the ejection failure is suppressed, so that the occurrence of thickness variation of the light conversion layer (for example, the color filter pixel portion included in the light conversion layer) is suppressed.

Hereinafter, the ink composition and the cleaning solution used in the printing method of the present embodiment will be described first.

[ink composition] The ink composition of this embodiment is an ink composition for forming a light conversion layer (for example, for forming a color filter pixel portion of a light conversion layer) for forming a light conversion layer included in a color filter and the like, and contains a luminescent nanoparticle Rice grains, and photopolymerizable compounds. The ink composition of this embodiment contains a photopolymerizable compound, so it can be called a photocurable ink composition. In addition, since the ink composition of this embodiment contains luminescent nanocrystals, it can also be called a luminescent ink composition. By irradiating the ink composition with light (active energy rays), the photopolymerizable compound can be polymerized and cured, and a light conversion layer (eg, color filter pixel portion) containing the cured product of the ink composition is formed.

The ink composition of the present embodiment is an ink jet ink composition for the ink jet method, and is appropriately prepared in a form suitable for the ink jet method. Therefore, the ink composition of this embodiment may further contain, for example, organic ligands, photopolymerization initiators, light scattering particles, polymer dispersants, oxidizing agents, etc.

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

Luminescent nanochips can, for example, emit light of a different wavelength (fluorescence or phosphorescence) than the absorbed wavelength by absorbing light of a specific wavelength. The luminescent nanocrystals can be red luminescent nanocrystals (red luminescent nanocrystals) that emit light (red light) with a luminescent peak wavelength in the range of 605-665 nm, and can be emitting in Green luminescent nanocrystals (green luminescent nanocrystals) with light emission peak wavelength (green light) in the range of 500-560 nm, can emit light with emission peak in the range of 420-480 nm Blue light-emitting nanocrystals (blue light-emitting nanocrystals) of wavelengths of light (blue light). The ink composition preferably contains at least one of these luminescent nanocrystals. In addition, the light absorbed by the luminescent nanochip can be, for example, light with a wavelength of 400 nm or more and less than 500 nm (especially light with a wavelength in the range of 420 to 480 nm) (blue light), or 200 nm to 500 nm. Light of wavelengths in the 400 nm range (ultraviolet light). In addition, the emission peak wavelength of the luminescent nanoparticle can be confirmed by, for example, a fluorescence spectrum or a phosphorescence spectrum measured using a spectrofluorophotometer.

The red luminescent nanocrystals are preferably 665 nm or less, 663 nm or less, 660 nm or less, 658 nm or less, 655 nm or less, 653 nm or less, 651 nm or less, 650 nm or less, 647 nm or less, 645 nm or less , 643 nm or less, 640 nm or less, 637 nm or less, 635 nm or less, 632 nm or less, or 630 nm or less have emission peak wavelengths, and preferably 628 nm or more, 625 nm or more, 623 nm or more, 620 nm or more, 615 nm or more, 610 nm or more, 607 nm or more, or 605 nm or more have emission peak wavelengths. These upper limit values and lower limit values can be combined arbitrarily. In addition, in the following identical descriptions, the upper limit value and the lower limit value may be described individually and may be combined arbitrarily.

The green light-emitting nanocrystals are preferably 560 nm or less, 557 nm or less, 555 nm or less, 550 nm or less, 547 nm or less, 545 nm or less, 543 nm or less, 540 nm or less, 537 nm or less, 535 nm or less , 532 nm or less or 530 nm or less has a peak emission wavelength, and preferably 528 nm or more, 525 nm or more, 523 nm or more, 520 nm or more, 515 nm or more, 510 nm or more, 507 nm or more, 505 nm or more, 503 nm or more or 500 nm or more has a luminescence peak wavelength.

The blue light-emitting nanocrystals are preferably 480 nm or less, 477 nm or less, 475 nm or less, 470 nm or less, 467 nm or less, 465 nm or less, 463 nm or less, 460 nm or less, 457 nm or less, 455 nm or less 452 nm or less, or 450 nm or less has a peak emission wavelength, and preferably 450 nm or more, 445 nm or more, 440 nm or more, 435 nm or more, 430 nm or more, 428 nm or more, 425 nm or more, 422 nm or more Or above 420 nm with a luminescence peak wavelength.

According to the solution of the Schrodinger wave Equation of the square-well potential model, the wavelength (luminescence color) of the light emitted by the luminescent nanocrystals depends on the size (eg particle size), but also depends on the energy gap that the luminescent nanocrystals have. Therefore, the luminescent color can be selected by changing the constituent material and size of the luminescent nanoparticle used.

The light-emitting nano-die may be a light-emitting nano-die containing a semiconductor material (light-emitting semiconductor nano-die). As a light-emitting semiconductor nanocrystal, a quantum dot, a quantum rod, etc. are mentioned. Among them, quantum dots are preferred from the viewpoints that the emission spectrum can be easily controlled, reliability can be ensured, production costs can be reduced, and mass productivity can be improved.

The light-emitting semiconductor nanoparticle may consist of only a core containing the first semiconductor material, or may have a core containing the first semiconductor material, and a second semiconductor material different from the first semiconductor material and covering at least a part of the core shell. In other words, the structure of the light-emitting semiconductor nanocrystal may be a structure composed of only a core (core structure) or a structure composed of a core and a shell (core/shell structure). In addition to the shell (first shell) containing the second semiconductor material, the light-emitting semiconductor nanoparticle may further include a third semiconductor material different from the first and second semiconductor materials and coat at least a part of the core Shell (Second Shell). In other words, the structure of the light-emitting semiconductor nanoparticle may also be a structure composed of a core, a first shell, and a second shell (core/shell/shell structure). The core and the shell can be mixed crystals containing two or more semiconductor materials (eg CdSe+CdS, CIS+ZnS, etc.).

The luminescent nanoparticle preferably contains: selected from the group consisting of II-VI semiconductors, III-V semiconductors, I-III-VI semiconductors, IV semiconductors and I-II-IV-VI semiconductors At least one of the semiconductor materials is used 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, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe; GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, InAlPSb; SnS, SnSe, SnTe, PbS, PbSe, 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 easily controlling the emission spectrum, ensuring reliability, reducing production cost, and improving mass productivity, the light-emitting semiconductor nanocrystal preferably contains a material 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 ,} At least one of the group consisting of CuGaSe ₂ , CuGaTe ₂ , Si, C, Ge and Cu ₂ ZnSnS ₄ .

Examples of red light-emitting semiconductor nanocrystals include: CdSe nanocrystals; nanocrystals with a core/shell structure in which the shell portion is CdS and the inner core portion is CdSe; Shell structure, and the shell part is CdS, the inner core part is ZnSe nanograin; CdSe and ZnS mixed crystal nanograin; InP nanograin; has a core/shell structure, and the shell The part is ZnS, and the inner core is InP nanocrystals; it has a core/shell structure, and the shell part is a mixed crystal of ZnS and ZnSe, and the inner core is InP nanocrystals; CdSe and CdS Mixed crystal nanograin; mixed crystal nanograin of ZnSe and CdS; with core/shell/shell structure, and the first shell part is ZnSe, the second shell part is ZnS, and the inner core part is InP Nanocrystalline grains; have a core/shell/shell structure, and the first shell part is a mixed crystal of ZnS and ZnSe, the second shell part is ZnS, and the inner core part is a nanocrystalline grain of InP, etc.

Examples of green light-emitting semiconductor nanocrystals include: CdSe nanocrystals; CdSe and ZnS mixed crystal nanocrystals; having a core/shell structure, and the shell portion is ZnS, and the inner core is The inner part is InP nanograin; the core/shell structure, and the shell part is a mixed crystal of ZnS and ZnSe, and the inner core part is InP nanograin; it has a core/shell/shell structure, and the first shell The part is ZnSe, the second shell part is ZnS, and the inner core part is InP nanograin; it has a core/shell/shell structure, and the first shell part is a mixed crystal of ZnS and ZnSe, and the second shell part is ZnS , The inner core is InP nanocrystals, etc.

Examples of blue light-emitting semiconductor nanocrystals include: ZnSe nanocrystals; ZnS nanocrystals; having a core/shell structure, and the shell portion is ZnSe, and the inner core portion is ZnS Nano-grain; CdS nano-grain; has a core/shell structure, and the shell part is ZnS, the inner core part is InP nano-grain; has a core/shell structure, and the shell part is ZnS and Mixed crystal of ZnSe, the inner core is InP nanocrystals; it has a core/shell/shell structure, and the first shell is ZnSe, the second shell is ZnS, and the inner core is InP nanocrystals It has a core/shell/shell structure, and the first shell part is a mixed crystal of ZnS and ZnSe, the second shell part is ZnS, and the inner core part is a nanocrystalline grain of InP, etc.

When semiconductor nanocrystals have the same chemical composition, the "color that should be emitted by the particle" can be changed to red or green by changing its own average particle size. In addition, it is preferable to use a semiconductor nano-die which has as little adverse effect on the human body as possible. In the case of using semiconductor nanocrystals containing cadmium, selenium, etc. as luminescent nanocrystals, it is better to select semiconductor nanocrystals that do not contain the above-mentioned elements (cadmium, selenium, etc.) as much as possible and use them alone. Or combined with other emissive nanoparticles to minimize the above elements.

The shape of the luminescent nanocrystals is not particularly limited, and may be any geometric shape or any irregular shape. The shape of the luminescent nanocrystals may be spherical, ellipsoid, pyramidal, disc, branch, mesh, rod, etc., for example. However, as the luminescent nanocrystals, in terms of further improving the uniformity and fluidity of the ink composition, it is preferable to use particles with less directivity (eg, spherical, tetrahedral, etc.) as the particle shape. equal particles).

The average particle diameter (volume average diameter) of the luminescent nanocrystals may be 1 nm or more, and may be 1.5 nm or more, from the viewpoint of easily obtaining light emission of a desired wavelength, and from the viewpoint of excellent dispersibility and storage stability. , and can be more than 2 nm. From the viewpoint of easily obtaining a desired emission wavelength, it may be 40 nm or less, 30 nm or less, or 20 nm or less. The average particle diameter (volume average diameter) of the luminescent nanocrystals is obtained by measuring with a transmission electron microscope or a scanning electron microscope, and calculating the volume average diameter.

From the viewpoint of dispersion stability, the luminescent nanoparticle preferably has an organic ligand on its surface. For example, the surface of the luminescent nanoparticle can be passivated by organic ligands. The organic ligands can be coordinately bonded to the surface of the luminescent nanocrystals. The organic ligands are detailed below.

The luminescent nanoparticle may also have a polymer dispersant on its surface. For example, the polymer dispersant can also be bound to the surface of the luminescent nanocrystal by exchanging the organic ligand bound on the surface of the luminescent nanocrystal with the polymer dispersant. However, from the viewpoint of dispersion stability when used as an inkjet ink, it is preferable to mix a polymer dispersant with the luminescent nanocrystals in the state where the organic ligands have been coordinated. The polymer dispersant will be described in detail below.

As the luminescent nanocrystals, those dispersed in a solvent, a photopolymerizable compound, or the like in a colloidal form can be used. The surfaces of the luminescent nanoparticles in the dispersed state are preferably passivated by organic ligands. Examples of the solvent include cyclohexane, hexane, heptane, chloroform, toluene, octane, chlorobenzene, tetralin, diphenyl ether, propylene glycol monomethyl ether acetate, and butyl carbitol acetic acid. Esters, or mixtures thereof.

As the luminescent nanocrystal, a commercial item can be used. Examples of commercially available luminescent nanocrystals include indium phosphide/zinc sulfide from NN-Labs, D-dots, CuInS/ZnS, and InP/ZnS from Aldrich.

From the viewpoint of further improving the external quantum efficiency of the pixel portion, the content of the luminescent nanocrystals is based on the total mass of the ink composition, preferably 20 mass % or more, and may be 22 mass % or more, 24 mass % or more. % or more or 26% by mass or more. According to the printing method of the present embodiment, even when the content of the luminescent nanocrystals is set to 20% by mass or more, it is difficult to cause poor ejection, so that less thickness variation and better external quantum efficiency can be obtained. light conversion layer. From the viewpoint of further improving the ejection stability and the external quantum efficiency of the pixel portion, the content of the luminescent nanocrystals is based on the total mass of the ink composition, preferably 80 mass % or less, and may be 70 mass % or less, 60 mass % or less, 50 mass % or less, or 40 mass % or less. From these viewpoints, the content of the luminescent nanocrystals can be based on the total mass of the ink composition, for example, 20 to 80 mass %, 22 to 70 mass %, 24 to 60 mass %, and 24 to 50 mass %. % or 26 to 40 mass %. Furthermore, the content of the above-mentioned luminescent nanocrystals does not contain the amount of organic ligands bound to the luminescent nanocrystals. In addition, in this specification, the "total mass of the ink composition" can be in other words the components that should be contained in the cured product of the ink composition. That is, when the ink composition contains a solvent, it refers to components other than the solvent contained in the ink composition. Unless otherwise specified, the amount of the solvent is not included in the total mass of the ink composition.

The ink composition may also contain two or more of red light-emitting nanocrystals, green light-emitting nanocrystals, and blue light-emitting nanocrystals as light-emitting nanocrystals, preferably only these One of the particles. When the ink composition contains red luminescent nanocrystals, the content of green luminescent nanocrystals and the content of blue luminescent nanocrystals are based on the total mass of the luminescent nanocrystals, and are higher than those of the green luminescent nanocrystals. Preferably it is 10 mass % or less, More preferably, it is 0 mass %. When the ink composition contains green luminescent nanocrystals, the content of the red luminescent nanocrystals and the content of the blue luminescent nanocrystals are based on the total mass of the luminescent nanocrystals, and are higher than those of the green luminescent nanocrystals. Preferably it is 10 mass % or less, More preferably, it is 0 mass %.

(organic ligand) The organic ligand exists near the surface of the luminescent nanocrystals, and has the function of dispersing the luminescent nanocrystals. The organic ligand has, for example, a functional group for securing affinity with a photopolymerizable compound, a solvent, etc. (hereinafter also simply referred to as an "affinity group"), and a functional group capable of bonding with luminescent nanocrystals ( The functional group for ensuring the adsorption to the luminescent nanocrystal) exists in the vicinity of the surface of the luminescent nanocrystal by coordinately bonding to the surface of the luminescent nanocrystal.

The affinity group can be a substituted or unsubstituted aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear or may have a branched structure. In addition, the aliphatic hydrocarbon group may or may not have an unsaturated bond. The substituted aliphatic hydrocarbon may also be a group in which a part of carbon atoms of the aliphatic hydrocarbon group is substituted by oxygen atoms. The substituted aliphatic hydrocarbon group may contain, for example, a (poly)oxyalkylene group. Here, the "(poly)oxyalkylene group" means at least one of an oxyalkylene group and a polyoxyalkylene group in which two or more alkylene groups are linked by an ether bond.

Examples of functional groups capable of bonding with light-emitting nanocrystals include a hydroxyl group, an amino group, a carboxyl group, a thiol group, a phosphoric acid group, a phosphonic acid group, a phosphine group, a phosphine group, and an alkoxysilyl group. (alkoxysilyl).

Examples of the organic ligand include TOP (trioctylphosphine), TOPO (trioctylphosphine oxide), oleic acid, linoleic acid, hypolinoleic acid, ricinoleic acid, gluconic acid, 16-hydroxyl hexadecanoic acid, 12-hydroxystearic acid, lauryl sarcosine, N-oleyl sarcosine, oleylamine, octylamine, trioctylamine, cetylamine, octanethiol, dodecylamine Alkanethiol, hexylphosphonic acid (HPA), tetradecylphosphonic acid (TDPA), phenylphosphonic acid, and octylphosphinic acid (OPA).

[式（1-1）中，p表示0～50之整數，q表示0～50之整數]In one embodiment, the organic ligand may be an organic ligand represented by the following formula (1-1).

[In formula (1-1), p represents an integer of 0 to 50, and q represents an integer of 0 to 50]

In the organic ligand represented by formula (1-1), at least one of p and q is preferably 1 or more, and more preferably both p and q are 1 or more.

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

In formula (1-2), A ¹ represents a valent group containing a carboxyl group, A ² represents a valent group containing a hydroxyl group, R represents a hydrogen atom, a methyl group, or an ethyl group, and L represents a substituted or unsubstituted extension. In the alkyl group, r represents an integer of 0 or more. The number of carboxyl groups in one valent group including a carboxyl group may be two or more, two or more and four or less, or two. The number of carbon atoms in the alkylene group represented by L may be, for example, 1 to 10. In the alkylene group represented by L, a part of carbon atoms may be substituted with a hetero atom, or may be substituted with at least one hetero atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom. r may be an integer of 1-100, for example, or an integer of 10-20 may be sufficient.

From the viewpoint of excellent external quantum efficiency of the pixel portion (hardened product of the ink composition), the organic ligand may be an organic ligand represented by the following formula (1-2A).

In formula (1-2A), r has the same meaning as above.

In one embodiment, the organic ligand may also be an organic ligand represented by the following formula (1-3).

In formula (1-3), n represents an integer of 0-50, and m represents an integer of 0-50. n is preferably 0-20, more preferably 0-10. m is preferably 0-20, more preferably 0-10. 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 carbon number of the alkylene group may be, for example, 1-10. In the alkylene group represented by Z, a part of carbon atoms may be substituted with a hetero atom, or may be substituted with at least one hetero atom selected from the group consisting of an oxygen atom, a sulfur atom and a nitrogen atom.

[式（1-4）中，l表示1～50之整數]In one embodiment, the organic ligand may also be an organic ligand represented by the following formula (1-4).

[In formula (1-4), l represents an integer of 1 to 50]

In the organic ligand represented by the formula (1-4), l can be 1-20, 3-15, 5-10, or 7.

From the viewpoint of the dispersion stability of the luminescent nanocrystals and the maintenance of the luminescent properties, the content of the organic ligand in the ink composition may be 10 parts by mass relative to 100 parts by mass of the luminescent nanocrystals or more, 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, or 40 parts by mass or more. From the viewpoint of easily keeping the viscosity of the ink composition low, the content of the organic ligand in the ink composition may be 50 parts by mass or less, 45 parts by mass or less, or less than 100 parts by mass of the luminescent nanocrystals. 40 parts by mass or less or 30 parts by mass or less. From these viewpoints, the content of the organic ligand may be, for example, 10 to 50 parts by mass or 10 to 15 parts by mass relative to 100 parts by mass of the luminescent nanocrystal grains.

(Photopolymerizable compound) The photopolymerizable compound is a compound polymerized by irradiation with light, and is, for example, a radical polymerizable compound (photoradical polymerizable compound) or a cationically polymerizable compound (photocationic polymerizable compound). The photopolymerizable compound may be a photopolymerizable monomer or oligomer. It and the like are used together with a photopolymerization initiator. The photoradical polymerizable compound is used together with the photoradical polymerization initiator, and the photocationic polymerizable compound is used together with the photocationic polymerization initiator. In other words, the ink composition may contain a photopolymerizable component containing a photopolymerizable compound and a photopolymerization initiator, or may contain a photoradical polymerizable component containing a photoradical polymerizable compound and a photoradical polymerization initiator, A photocationically polymerizable component containing a photocationic polymerizable compound and a photocationic polymerization initiator may also be contained. A photoradical polymerizable compound and a photocationic polymerizable compound may be used together, a compound having photoradical polymerizability and photocationic polymerizability may be used, and a photoradical polymerization initiator and a photocationic polymerization initiator may be used together. The ink composition may contain one type of photopolymerizable compound, or two or more types, and preferably two or more types.

As a photoradical polymerizable compound, the monomer which has an ethylenically unsaturated group (henceforth "ethylenically unsaturated monomer"), the monomer which has an isocyanate group, etc. are mentioned, for example. Here, the ethylenically unsaturated monosystem refers to a monomer having an ethylenically unsaturated bond (carbon-carbon double bond). As an ethylenically unsaturated monomer, the monomer which has an ethylenically unsaturated group, such as a vinyl group, a vinyl group, a vinylidene group, is mentioned, for example. Monomers having these groups are sometimes referred to as "vinyl monomers".

The number of ethylenically unsaturated bonds (for example, the number of ethylenically unsaturated groups) in the ethylenically unsaturated monomer is, for example, 1-3. An ethylenically unsaturated monomer may be used individually by 1 type, and may be used in combination of a plurality of types. The photopolymerizable compound may contain a monomer having one ethylenically unsaturated group (monofunctional ), and monomers with two or more ethylenically unsaturated groups (polyfunctional monomers), which may include monofunctional monomers, and monomers (difunctional monomers) selected from the group consisting of two ethylenically unsaturated groups (difunctional monomers) and At least one of the group consisting of monomers having three ethylenically unsaturated groups (trifunctional monomers).

The ethylenically unsaturated group may be a vinyl group, a vinylidene group, a vinylidene group, a (meth)acryloyl group, etc., preferably a (meth)acryloyl group. In addition, in this specification, "(meth)acryloyl group" means "acryloyl group" and the corresponding "methacryloyl group". The same applies to the expressions of "(meth)acrylate" and "(meth)acrylamide".

The photopolymerizable compound preferably contains at least one compound having a (meth)acryloyl group as an ethylenically unsaturated group, and more preferably contains at least one compound selected from the group consisting of (meth)acrylate and (meth)acryloyl At least one of the group consisting of amines, more preferably at least one containing (meth)acrylate, particularly preferably at least one containing (meth)acrylate having a linear alkyl group having 8 or more carbon atoms 1 type. The photopolymerizable compound preferably contains two or more (meth)acrylates, more preferably contains two or more (meth)acrylates from the viewpoint of being easy to combine excellent ejection stability and excellent curability, and from the viewpoint of further improving the external quantum efficiency. (Meth)acrylates having one (meth)acryloyl group (monofunctional (meth)acrylates), and (meth)acrylates having two or more (meth)acryloyl groups (polyfunctional (meth)acrylate), more preferably a monofunctional (meth)acrylate, and a (meth)acrylate having two (meth)acryloyl groups (difunctional (meth)acrylic acid) selected from the group consisting of At least one of the group consisting of (meth)acrylates having three (meth)acryloyl groups (trifunctional (meth)acrylates).

啉、N-第三丁基丙烯醯胺、N-羥甲基丙烯醯胺、N-羥乙基丙烯醯胺、N-第三辛基丙烯醯胺、N-丁氧甲基丙烯醯胺、N-苯基丙烯醯胺、N-十二烷基丙烯醯胺等。其中，適宜使用(甲基)丙烯酸乙氧基乙氧基乙酯及雙丙酮丙烯醯胺。As the monofunctional monomer, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and amyl (meth)acrylate may be mentioned. , 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, cetyl (meth)acrylate , Octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, methoxyethyl (meth)acrylate, butoxyethyl (meth)acrylate, phenoxy (meth)acrylate Ethyl (meth)acrylate, nonylphenoxyethyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, Ethoxyethoxyethyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, bicyclo (meth)acrylate Pentenyloxyethyl ester, 2-hydroxy-3-phenoxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid Benzyl ester, phenylbenzyl (meth)acrylate, mono(2-acryloyloxyethyl succinate), mono(2-methacryloyloxyethyl succinate), N-[2-(propylene) Acryloyloxy)ethyl]phthalimide, N-[2-(acryloyloxy)ethyl]tetrahydrophthalimide, 4-hydroxybutyl acrylate, 2-hydroxy acrylate Propyl ester, 2-hydroxyethyl acrylate, acrylamide, N-isopropyl acrylamide, N,N-dimethyl acrylamide, N,N-diethyl acrylamide, diacetone acrylamide , 4-Propylene Glycol

Linen, N-tert-butyl acrylamide, N-methylol acrylamide, N-hydroxyethyl acrylamide, N-tert-octyl acrylamide, N-butoxymethyl acrylamide, N-Phenyl acrylamide, N-dodecyl acrylamide, etc. Among them, ethoxyethoxyethyl (meth)acrylate and diacetone acrylamide are suitably used.

Specific examples of the monomer (difunctional monomer) having two ethylenically unsaturated groups 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 Meth)acrylate, neopentyl glycol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclic Decane dimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate ) acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol hydroxypivalate diacrylate, tris(2-hydroxyethyl) isocyanurate 2 hydroxyl groups are substituted with (meth)acryloyloxy di(meth)acrylate, obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol The 2 hydroxyl groups of the diol are substituted with (meth)acryloyloxy di(meth)acrylate, and 2 moles of ethylene oxide or propylene oxide are added to 1 mole of bisphenol A to obtain The 2 hydroxyl groups of the diols are substituted with (meth)acryloyloxy di(meth)acrylate, 3 mol or more of ethylene oxide or cyclic ethylene oxide is added to 1 mol of trimethylolpropane The two hydroxyl groups of the triol obtained by oxypropane are substituted with di(meth)acrylate of (meth)acryloyloxy, and 4 mol or more of ethylene oxide is added to 1 mol of bisphenol A or propylene oxide, the 2 hydroxyl groups of the diols are substituted with (meth)acryloyloxy di(meth)acrylate, N,N'-methylenebisacrylamide, N,N' -Ethylene bisacrylamide, etc. Among them, dipropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, and 1,6-hexanediol diacrylate are suitably used.

As a specific example of the monomer (trifunctional monomer) which has three ethylenically unsaturated groups, glycerol tri(meth)acrylate, trimethylolethane tri(meth)acrylate, etc. are mentioned. Among them, glycerol tri(meth)acrylate is suitably used.

As a photocationically polymerizable compound, an epoxy compound, an oxetane compound, a vinyl ether compound, etc. are mentioned.

As the epoxy compound, bisphenol A type epoxy compound, bisphenol F type epoxy compound, phenol novolak type epoxy compound, trimethylolpropane polyglycidyl ether, neopentyl glycol diglycidyl can be mentioned Aliphatic epoxy compounds such as ethers; 1,2-epoxy-4-vinylcyclohexane, 1-methyl-4-(2-methyloxiranyl)-7-oxabicyclo[4.1 .0] Alicyclic epoxy compounds such as heptane, etc.

As an epoxy compound, a commercial item can also be used. As a commercial item of an epoxy compound, "Celloxide 2000", "Celloxide 3000", "Celloxide 4000" by Daicel Chemical Industry Co., Ltd., etc. can be used, for example.

The cationically polymerizable oxetane compound may, for example, include 2-ethylhexyl oxetane, 3-hydroxymethyl-3-methyl oxetane, 3-hydroxymethyl-3-ethyl oxetane, 3-hydroxymethyl-3-propyl oxetane, 3-hydroxymethyl-3-n-butyl oxetane, 3-hydroxymethyl-3-phenyl oxetane , 3-hydroxymethyl-3-benzyl oxetane, 3-hydroxyethyl-3-methyl oxetane, 3-hydroxyethyl-3-ethyl oxetane, 3-hydroxyethyl yl-3-propyl oxetane, 3-hydroxyethyl-3-phenyl oxetane, 3-hydroxypropyl-3-methyl oxetane, 3-hydroxypropyl-3-ethyl oxetane, 3-hydroxypropyl-3-propyl oxetane, 3-hydroxypropyl-3-phenyl oxetane, 3-hydroxybutyl-3-methyl oxetane Wait.

As an oxetane compound, a commercial item can also be used. As commercially available oxetane compounds, for example, ARONE OXETANE series ("OXT-101", "OXT-212", "OXT-121", "OXT-221", etc.) manufactured by Toagosei Co., Ltd. can be used ; "Celloxide 2021", "Celloxide 2021A", "Celloxide 2021P", "Celloxide 2080", "Celloxide 2081", "Celloxide 2083", "Celloxide 2085", "Epolead GT300", "Celloxide 2081" manufactured by Daicel Chemical Industry Co., Ltd. "Epolead GT301", "Epolead GT302", "Epolead GT400", "Epolead GT401" and "Epolead GT403"; "Cyracure UVR-6105", "Cyracure UVR-6107", "Cyracure UVR- 6110", "Cyracure UVR-6128", "ERL4289" and "ERL4299", etc. Moreover, a well-known oxetane compound (for example, the oxetane compound described in Unexamined-Japanese-Patent No. 2009-40830 etc.) can also be used.

As a vinyl ether compound, 2-hydroxyethyl vinyl ether, triethylene glycol vinyl monoether, tetraethylene glycol divinyl ether, trimethylolpropane trivinyl ether, etc. are mentioned.

In addition, as the photopolymerizable compound in the present embodiment, the photopolymerizable compounds described in paragraphs 0042 to 0049 of JP 2013-182215 A can also be used.

From the viewpoint of reducing stickiness (wrinkle) on the surface of the cured product of the ink composition, it is preferable to use a radically polymerizable compound having a cyclic structure as the photopolymerizable compound. The cyclic structure may be an aromatic ring structure or a non-aromatic ring structure. The number of cyclic structures (the total number of aromatic rings and non-aromatic rings) may be one, or two or more. The number of ring structures may be three or less. The number of carbon atoms constituting the cyclic structure is, for example, 4 or more, and may be 5 or more or 6 or more. The number of carbon atoms is, for example, 20 or less, or 18 or less.

The aromatic ring structure may be, for example, a structure having an aromatic ring having 6 to 18 carbon atoms. As a C6-C18 aromatic ring, a benzene ring, a naphthalene ring, a phenanthrene ring, an anthracene ring, etc. are mentioned. The aromatic ring structure may also be a structure having an aromatic heterocyclic ring. As an aromatic heterocyclic ring, a furan ring, a pyrrole ring, a piperane ring, a pyridine ring, etc. are mentioned, for example. The number of aromatic rings may be one or two or more. The number of aromatic rings may be 3 or less. The organic group may have a structure in which two or more aromatic rings are bonded by a single bond (for example, a biphenyl structure).

The non-aromatic ring structure may be, for example, a structure having an alicyclic ring having 5 to 20 carbon atoms. Examples of the alicyclic ring having 5 to 20 carbon atoms include cycloalkane rings such as a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, and a cyclooctane ring; a cyclopentene ring, a cyclohexene ring, and a cycloheptene ring Cycloalkene rings such as alkene rings, cyclooctene rings, etc. The alicyclic ring may also be a condensed ring such as a bicycloundecane ring, a decahydronaphthalene ring, a norbornene ring, a norbornadiene ring, and an isobornyl ring. The non-aromatic ring structure may also be a structure having a non-aromatic heterocyclic ring. As a non-aromatic heterocyclic ring, a tetrahydrofuran ring, a pyrrolidine ring, a tetrahydropyran ring, a piperidine ring, etc. are mentioned, for example.

The radically polymerizable compound having a cyclic structure is preferably a monofunctional or polyfunctional (meth)acrylate having a cyclic structure, and more preferably a monofunctional (meth)acrylate having a cyclic structure. Specifically, phenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, biphenyl (meth)acrylate, isobornyl (meth)acrylate, (meth)acrylate are preferably used. base) tetrahydrofurfuryl acrylate, dicyclopentenyloxyethyl (meth)acrylate, etc.

From the viewpoint of easily suppressing stickiness (wrinkling) on the surface of the ink composition, the content of the radically polymerizable compound having a cyclic structure may be 3% by mass or more and 5% by mass based on the total mass of the ink composition. mass % or more or 10 mass % or more. From the viewpoint of easily obtaining a suitable viscosity as an inkjet ink and easily obtaining excellent ejectability, the content of the radically polymerizable compound having a cyclic structure may be 80% based on the total mass of the ink composition. mass % or less, 60 mass % or less, or 45 mass % or less.

From the viewpoint of easily obtaining excellent ejectability, it is preferable to use a radically polymerizable compound having a linear structure with 4 or more carbon atoms as the ink composition. The straight-chain structure may be a structure in which atoms other than a hydrogen atom are connected without branching, and may have a hetero atom such as an oxygen atom in addition to a carbon atom and a hydrogen atom. That is, the straight-chain structure is not limited to a structure in which four or more carbon atoms are connected in a straight-chain form, and a straight-chain structure in which four or more carbon atoms are connected via a heteroatom such as an oxygen atom may be used. The straight chain structure may have an unsaturated bond, but it is preferably composed of only a saturated bond structure. The number of carbon atoms constituting the linear structure is preferably 5 or more, more preferably 6 or more, and still more preferably 7 or more. The number of carbon atoms constituting the linear structure is preferably 25 or less, more preferably 20 or less, and still more preferably 15 or less. Furthermore, it is preferable that the radically polymerizable compound which has a linear structure with a total carbon number of 4 or more does not have a cyclic structure from a viewpoint of dischargeability.

The straight-chain structure may be, for example, a structure having a straight-chain alkyl group having 4 or more carbon atoms. Examples of linear alkyl groups having 4 or more carbon atoms include butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, and tridecyl. , tetradecyl, pentadecyl, etc. As a radically polymerizable compound which has such a structure, the (meth)acrylic-acid alkylester which directly couple|bonded the said linear alkyl group to a (meth)acryloyloxy group is used suitably.

The straight-chain structure may be, for example, a structure having a straight-chain alkyl group having 4 or more carbon atoms. Examples of linear alkylene groups having 4 or more carbon atoms include butylene, pentylene, hexylene, heptyl, octyl, nononyl, decyl, undecenyl, Dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, etc. As the radically polymerizable compound having such a structure, an alkylene glycol di(meth)acrylate in which two (meth)acryloyloxy groups are bonded to the above linear alkyl group is preferably used.

The straight-chain structure may be, for example, a structure in which a straight-chain alkyl group and one or more straight-chain alkylene groups are bonded via an oxygen atom (a structure having an alkyl (poly)oxyalkylene group). The number of straight-chain alkyl groups may be 2 or more, and may be 6 or less. When the number of straight-chain alkyl groups is two or more, the two or more alkyl groups may be the same or different. The number of carbon atoms in the linear alkyl group and the linear extended alkyl group may be 1 or more, and may be 2 or more or 3 or more. The carbon number of the straight-chain alkyl group and the straight-chain extended alkyl group may be 4 or less. As a linear alkyl group, a methyl group, an ethyl group, and a propyl group are mentioned other than the said C4 or more linear alkyl group. As the straight-chain alkylene group, in addition to the above-mentioned straight-chain alkylene group having 4 or more carbon atoms, a methylene group, an ethylidene group, and a propylidene group may, for example, be mentioned. As the radically polymerizable compound having such a structure, an alkyl (poly)oxyalkylene group (poly)oxyalkylene group (poly)oxyalkylene group ( meth)acrylate.

A radically polymerizable compound having a straight-chain structure having a carbon number of 4 or more from the viewpoint of easily obtaining a viscosity suitable for inkjet ink and easily obtaining excellent dischargeability, and from the viewpoint of having excellent curability of the ink composition The content may be 1 mass % or more, 3 mass % or more, or 5 mass % or more based on the total mass of the ink composition. From the viewpoint of easily suppressing stickiness (wrinkling) on the surface of the ink composition, the content of the radically polymerizable compound having a linear structure with a carbon number of 4 or more is based on the total mass of the ink composition, and may be 80 mass % or less, 60 mass % or less, or 45 mass % or less.

As the photopolymerizable compound, from the viewpoint of excellent uniformity of the surface of the pixel portion, it is preferable to use two or more types of radically polymerizable compounds, and it is more preferable to use the above-mentioned radically polymerizable compound having a cyclic structure, It is used in combination with the above-mentioned radically polymerizable compound having a linear structure with 4 or more carbon atoms. In order to improve the external quantum efficiency, the uniformity of the surface of the pixel portion may decrease when the amount of the luminescent nanocrystals is increased, but even in this case, by combining the above-mentioned photopolymerizable compounds, it is possible to There is a tendency to obtain a pixel portion with excellent surface uniformity.

When the above-mentioned radically polymerizable compound having a cyclic structure and the above-mentioned radically polymerizable compound having a linear structure having 4 or more carbon atoms are used in combination, from the viewpoint of excellent uniformity of the surface of the pixel portion. In other words, the mass ratio (M ₂ /M ₁ ) of the content M ₂ of the radically polymerizable compound having a linear structure having a carbon number of 4 or more relative to the content M ₁ of the radically polymerizable compound having a cyclic structure is preferable It is 0.05-5, More preferably, it is 0.1-3, More preferably, it is 0.1-1.

The photopolymerizable compound may be alkali-insoluble from the viewpoint of easily obtaining a pixel portion (hardened product of the ink composition) excellent in reliability. In this specification, the term that the photopolymerizable compound is alkali-insoluble means that the dissolved amount of the photopolymerizable compound at 25°C in 1 mass % potassium hydroxide aqueous solution is 30 mass based on the total mass of the photopolymerizable compound. %the following. The said dissolved amount of a photopolymerizable compound becomes like this. Preferably it is 10 mass % or less, More preferably, it is 3 mass % or less.

From the viewpoint of easily obtaining a suitable viscosity as an inkjet ink, the viewpoint that the curability of the ink composition becomes good, and the viewpoint that the solvent resistance and abrasion resistance of the pixel portion (hardened product of the ink composition) are improved. In other words, the content of the photopolymerizable compound may be 10% by mass or more, 15% by mass or more, or 20% by mass or more based on the total mass of the ink composition. From the viewpoint of easily obtaining a suitable viscosity as an inkjet ink, and from the viewpoint of obtaining more excellent optical properties (such as external quantum efficiency), the content of the photopolymerizable compound is based on the total mass of the ink composition. It may be 60 mass % or less, 50 mass % or less, 40 mass % or less, 30 mass % or less, or 20 mass % or less. From these viewpoints, the content of the photopolymerizable compound may be, for example, 10 to 60 mass %, 15 to 50 mass %, 20 to 40 mass %, or 20 to 30 mass % based on the total mass of the ink composition. .

(photopolymerization initiator) The photopolymerization initiator is, for example, a photoradical polymerization initiator or a photocationic polymerization initiator. As the photoradical polymerization initiator, a molecular cleavage type or a hydrogen abstraction type photoradical polymerization initiator is suitable.

、2-異丙基-9-氧硫𠮿

、2,4,6-三甲基苯甲醯基二苯基氧化膦、2-苄基-2-二甲胺基-1-(4-

啉基苯基)-丁烷-1-酮、雙(2,6-二甲氧基苯甲醯基)-2,4,4-三甲基戊基氧化膦、(2,4,6-三甲基苯甲醯基)乙氧基苯基氧化膦等。作為除其等以外之分子裂解型光自由基聚合起始劑，亦可併用1-羥基環己基苯基酮、安息香乙醚、苯偶醯二甲基縮酮、2-羥基-2-甲基-1-苯基丙烷-1-酮、1-(4-異丙基苯基)-2-羥基-2-甲基丙烷-1-酮及2-甲基-1-(4-甲硫基苯基)-2-

啉基丙烷-1-酮。As a molecular cleavage type photo-radical polymerization initiator, suitable use: benzoin isobutyl ether, 2,4-diethyl-9-oxothioate

, 2-isopropyl-9-oxothio

, 2,4,6-trimethylbenzyldiphenylphosphine oxide, 2-benzyl-2-dimethylamino-1-(4-

Linophenyl)-butan-1-one, bis(2,6-dimethoxybenzyl)-2,4,4-trimethylpentylphosphine oxide, (2,4,6- Trimethylbenzyl)ethoxyphenylphosphine oxide and the like. As a molecular cleavage type photoradical polymerization initiator other than these, 1-hydroxycyclohexyl phenyl ketone, benzoin ether, benzil dimethyl ketal, 2-hydroxy-2-methyl- 1-Phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one and 2-methyl-1-(4-methylthiobenzene) base)-2-

Linopropan-1-one.

Examples of hydrogen abstraction type photoradical polymerization initiators include: benzophenone, 4-phenylbenzophenone, isophthalic ketone, 4-benzyl-4'-methyl-diphenone Phenyl sulfide, etc. A molecular cleavage-type photo-radical polymerization initiator and a hydrogen abstraction-type photo-radical polymerization initiator may also be used in combination.

As a photocationic polymerization initiator, a commercial item can also be used. Examples of commercially available products include perium salt-based photocationic polymerization initiators such as "CPI-100P" manufactured by San-Apro, acyl phosphine oxide compounds such as "Lucirin TPO" manufactured by BASF, and "Irgacure 907", "Irgacure 819", "Irgacure 379EG", "Irgacure 184" and "Irgacure PAG290", etc.

From the viewpoint of the curability of the ink composition, the content of the photopolymerization initiator may be 0.1 part by mass or more, 0.5 part by mass or more, or 1 part by mass relative to 100 parts by mass of the photopolymerizable compound. The above may be 3 parts by mass or more, or 5 parts by mass or more. The content of the photopolymerization initiator may be 40 parts by mass or less, or may be 30 parts by mass relative to 100 parts by mass of the photopolymerizable compound, from the viewpoint of the stability over time of the pixel portion (hardened product of the ink composition). part or less, may be 20 parts by mass or less, or may be 10 parts by mass or less. From these viewpoints, the content of the photopolymerization initiator may be, for example, 0.1 to 40 parts by mass relative to 100 parts by mass of the photopolymerizable compound.

(light scattering particles) The light-scattering particles are, for example, optically inert inorganic fine particles. When the ink composition contains light-scattering particles, the light from the light source irradiated to the pixel portion can be scattered, so that excellent optical properties (eg, external quantum efficiency) can be obtained.

Examples of materials constituting the light-scattering particles include simple metals such as tungsten, zirconium, titanium, platinum, bismuth, rhodium, palladium, silver, tin, platinum, and gold; silica, barium sulfate, and talc. , clay, kaolin, aluminum white, titanium oxide, 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; Metal hydroxides such as aluminum hydroxide; composite oxides such as barium zirconate, calcium zirconate, calcium titanate, barium titanate, strontium titanate, metal salts such as bismuth subnitrite, etc. From the viewpoint of excellent ejection stability and from the viewpoint of more excellent effect of improving external quantum efficiency, the light-scattering particles preferably contain titanium oxide, aluminum oxide, zirconium oxide, zinc oxide, calcium carbonate, barium sulfate, and titanium oxide. At least one kind selected from the group consisting of barium oxide and silicon dioxide, more preferably at least one kind selected from the group consisting of titanium oxide, zirconium oxide, zinc oxide, and barium titanate.

The shape of the light-scattering particles may be spherical, filamentous, indeterminate, or the like. However, as the light-scattering particles, since the uniformity, fluidity, and light-scattering properties of the ink composition can be further improved, and excellent ejection stability can be obtained, it is preferable to use the particles with less directivity as the particle shape. Particles (eg, spherical, tetrahedral, etc.).

From the viewpoint of excellent ejection stability and from the viewpoint of more excellent effect of improving external quantum efficiency, the average particle diameter (volume average diameter) of the light-scattering particles in the ink composition may be 0.05 μm (50 nm) or more, or It can be 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 diameter (volume average diameter) of the light-scattering particles in the ink composition may be 1.0 μm (1000 nm) or less, or 0.6 μm (600 nm) or less, It can also be 0.4 μm (400 nm) or less. The average particle diameter (volume average diameter) of the light-scattering particles in the ink composition may be 0.05 to 1.0 μm, 0.05 to 0.6 μm, 0.05 to 0.4 μm, 0.2 to 1.0 μm, 0.2 to 0.6 μm, 0.2 to 0.4 μm , 0.3 to 1.0 μm, 0.3 to 0.6 μm, or 0.3 to 0.4 μm. From the viewpoint of easily obtaining such an average particle diameter (volume average diameter), the average particle diameter (volume average diameter) of the light-scattering particles used may be 0.05 μm or more, or 1.0 μm or less. In this specification, the average particle diameter (volume average diameter) of the light scattering particles in the ink composition can be obtained by measuring with a dynamic light scattering type Nanotrac particle size distribution meter, and calculating the volume average diameter. In addition, the average particle diameter (volume average diameter) of the light-scattering particles used can be obtained by, for example, measuring the particle diameter of each particle with a transmission electron microscope or a scanning electron microscope, and calculating the volume average diameter.

From the viewpoint that the effect of improving the external quantum efficiency is more excellent, the content of the light-scattering particles in the ink composition is based on the total mass of the ink composition, for example, 0.1 mass % or more, or 1 mass % or more. or 2% by mass or more. The content of the light-scattering particles is based on the total mass of the ink composition, and is, for example, 60% by mass or less. The content of the light-scattering particles is preferably 10% by mass or less, more preferably 7% by mass or less, and still more preferably 5% by mass, from the viewpoint of being excellent in ejection stability and more excellent in the effect of improving the external quantum efficiency. the following. From these viewpoints, the content of the light-scattering particles is preferably 0.1 to 10% by mass based on the total mass of the ink composition.

From the viewpoint of being excellent in the effect of improving the external quantum efficiency, the mass ratio of the content of the light-scattering particles to the content of the luminescent nanocrystals (light-scattering particles/luminescent nanocrystals) may be 0.05 or more, It may be 0.1 or more, 0.2 or more, or 0.5 or more. The mass ratio (light-scattering particles/luminescent nanocrystals) may be 5.0 or less, from the viewpoint of being more excellent in the effect of improving the external quantum efficiency and excellent in the continuous ejection (discharging stability) during inkjet printing. 2.0 or less may be sufficient, and 1.5 or less may be sufficient. From these viewpoints, the mass ratio (light-scattering particles/luminescent nanocrystals) may be, for example, 0.05 to 5.0.

(polymer dispersant) The polymer dispersant is a polymer compound having a weight average molecular weight of 750 or more and a functional group having an affinity for light-scattering particles. The polymer dispersant has a function of dispersing light-scattering particles. The polymer dispersing agent is adsorbed (for example, bound) to the light scattering particles through the functional group having an affinity for the light scattering particles, and the light scattering particles are dispersed by the electrostatic repulsion and/or steric repulsion of the polymer dispersing agents. in ink compositions. The polymer dispersant is preferably combined with the surface of the light-scattering particles and adsorbed on the light-scattering particles, but it can also be combined with the surface of the luminescent nanocrystals to be adsorbed on the luminescent nanoparticles, and can also be formed in the ink composition free in matter.

As a functional group which has affinity with respect to a light-scattering particle, an acidic functional group, a basic functional group, and a nonionic functional group are mentioned. Acidic functional groups have dissociative protons, and can be neutralized by bases such as amines and hydroxide ions, and basic functional groups can also be neutralized by acids such as organic acids and inorganic acids.

As the acidic functional group, a carboxyl group (—COOH), a sulfo group (—SO ₃ H), a sulfate group (—OSO ₃ H), a phosphonic acid group (—PO(OH) ₃ ), a phosphoric acid group (—OPO (OH) ₃ ), phosphinic acid group (-PO(OH)-), mercapto group (-SH) and the like.

、咪唑、三唑等含氮雜環基等。Examples of basic functional groups include primary, secondary and tertiary amine groups, ammonium groups, imino groups, and pyridine, pyrimidine, pyridine

, imidazole, triazole and other nitrogen-containing heterocyclic groups, etc.

Examples of the nonionic functional group include a hydroxyl group, an ether group, a thioether group, a sulfinyl group (-SO-), a sulfonyl group (-SO ₂ -), a carbonyl group, a carboxyl group, an ester group, and a carbonic acid group. Ester, amide, carbamoyl, ureido, thioamide, thiourea, sulfamoyl, cyano, alkenyl, alkynyl, phosphinyl, thiophosphino.

The polymer dispersant can be a polymer of a single monomer (homopolymer) or a copolymer of multiple monomers. In addition, 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 dispersing agent can be, for example, acrylic resin, polyester resin, polyurethane resin, polyamide resin, polyether, phenolic resin, polysiloxane, polyurea resin, amine resin, epoxy resin, polystyrene Polyamines such as ethylimine and polyallylamine, polyimide, etc.

As the polymer dispersing agent, commercially available products can also be used, and as commercial products, Ajisper PB series manufactured by Ajinomoto Fine-Techno Co., Ltd., DISPERBYK series and BYK-series manufactured by BYK Corporation, and Efka series manufactured by BASF Corporation can be used Wait.

(other ingredients) The ink composition may further contain components other than the above components within a range that does not inhibit the effects of the present invention.

For example, the ink composition may further contain a solvent. Examples of the solvent include cyclohexane, hexane, heptane, chloroform, toluene, octane, chlorobenzene, tetralin, diphenyl ether, propylene glycol monomethyl ether acetate, and butyl carbitol acetic acid. Esters, or mixtures thereof, etc. However, in the ink composition of the present embodiment, the photopolymerizable compound also functions as a dispersion medium, so that the light scattering particles and the luminescent nanocrystals can be dispersed without a solvent. In this case, there is an advantage that the step of removing the solvent by drying is not required when the pixel portion is formed. When the ink composition contains a solvent, the content of the solvent may exceed 0 mass % and be 5 mass % or less based on the total mass of the ink composition (including the solvent).

For example, the ink composition may further contain a modified polysiloxane. The modified polysiloxane has a dimethyl polysiloxane structure and has a structure in which a part of its methyl group is substituted with an organic group. Dimethylpolysiloxane is also known as polydimethylsiloxane. As an organic group substituted for a methyl group, a substituted or unsubstituted alkyl group, an aralkyl group, a polyether group, etc. are mentioned. As a substituted alkyl group, the alkyl group substituted with an epoxy group, a hydroxyl group, a methacryloyloxy group, an acryloxy group, etc. is mentioned. The ink composition contains one or more of the modified polysiloxanes.

The modified polysiloxane is preferably selected from the group consisting of polyether-modified polysiloxane, aralkyl-modified polysiloxane, and polyether-modified and aralkyl-modified polysiloxane (using polyether-based At least one of the group consisting of modified polysiloxanes modified with both aralkyl groups.

A commercial item can be used for the modified polysiloxane. Specific examples of the commercially available products are shown below. ・Made by BYK-Chemie: BYK-300, 302, 306, 307, 310, 315, 320, 322, 323, 325, 330, 331, 333, 337, 340, 344, 347, 348, 370, 375, 377 , 355, 356, 357, 390, UV3500, UV3510, UV3570, etc. ・Made by Tego Chemie: Tegorad-2100, 2200, 2250, 2500, 2700, TegoGlide-410, 432, 450, etc. ・Made by Shin-Etsu Silicones Co., Ltd.: KP341, KF6001, KF6002, KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF- 642, KF-643, KF-6020, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, KF-6017, etc. ・Dow Corning Toray (stock) manufacture: Toray Silicone DC3PA, Toray Silicone SH7PA, Toray Silicone DC11PA, Toray Silicone SH21PA, Toray Silicone SH28PA, Toray Silicone SH29PA, Toray Silicone SH30PA, Toray Silicone SH8400, etc. ・Manufactured by Momentive Advanced Materials: TSF-4440, TSF-4300, TSF-4445, TSF-4460, TSF-4452, etc.

From the viewpoint of better compatibility with the inkjet process, optical properties and reproducibility, the content of the modified polysiloxane may be 0.0001% by mass or more based on the total mass of the ink composition, It may be 0.001 mass % or more, 0.005 mass % or more, and 0.01 mass % or more. From the viewpoint of making the viscosity of the ink composition containing a high concentration of luminescent nanocrystals suitable for viscosity and surface tension by inkjet, the content of the modified polysiloxane is based on the total mass of the ink composition. On a basis, it may be 5 mass % or less, 2 mass % or less, 1 mass % or less, 0.5 mass % or less, 0.1 mass % or less, or 0.05 mass % or less. Especially when the modified polysiloxane has a mercapto group, an amine group, a carboxyl group, an epoxy group, etc., the modified polysiloxane is inhibited from reacting with the photopolymerizable compound or interacting with the luminescent nanocrystals. From the viewpoint of increasing viscosity, the content of the modified polysiloxane is preferably below the above-mentioned upper limit value.

The ink composition may further contain, for example, a thermosetting resin, a curing agent, a curing accelerator (curing catalyst), a polymerization inhibitor, a chain transfer agent, an antioxidant, and the like.

The viscosity of the ink composition described above may be 2 mPa·s or more, 5 mPa·s or more, or 7 mPa·s, for example, from the viewpoint of ejection stability during inkjet printing. above. The viscosity of the ink composition may be 20 mPa·s or less, 15 mPa·s or less, or 12 mPa·s or less. The viscosity of the ink composition may be, for example, 2 to 20 mPa·s, 2 to 15 mPa·s, 2 to 12 mPa·s, 5 to 20 mPa·s, 5 to 15 mPa·s, and 5 to 12 mPa·s. , 7 to 20 mPa·s, 7 to 15 mPa·s, or 7 to 12 mPa·s. In addition, the said viscosity is the viscosity at the ink temperature at the time of implementing inkjet printing, for example, and it is the viscosity measured with the E-type viscometer. The ink temperature when performing inkjet printing is preferably 25 to 60°C, more preferably 30 to 55°C, and still more preferably 30 to 40°C. The temperature of the ink when performing inkjet printing is adjusted by the temperature of the inkjet head when performing inkjet printing.

When the ink composition is in inkjet printing, when the viscosity of the ink temperature is 2 mPa·s or more, since the meniscus shape of the inkjet ink at the front end of the ink ejection hole of the inkjet head is stable, the ejection of the inkjet ink is stable. Control (for example, control of ejection amount and ejection timing) becomes easy. On the other hand, when the viscosity of the ink composition is 20 mPa·s or less at the ink temperature during inkjet printing, the inkjet ink can be smoothly ejected from the ink ejection hole.

The surface tension of the ink composition is preferably a surface tension suitable for an inkjet method, specifically, preferably in the range of 20-40 mN/m, more preferably 25-35 mN/m. By setting the surface tension to this range, ejection control (eg, control of ejection amount and ejection timing) becomes easy, and the occurrence of flight deviation can be suppressed. Furthermore, the flying offset refers to a deviation of 30 μm or more from the sprayed position of the ink composition relative to the target position when the ink composition is ejected from the ink ejection hole. When the surface tension is 40 mN/m or less, since the shape of the meniscus at the tip of the ink ejection hole is stable, the ejection control of the ink composition (for example, the ejection amount and ejection timing control) becomes easy. On the other hand, in the case where the surface tension is 20 mN/m or more, since the contamination of the periphery of the ink ejection hole with the ink jet ink can be prevented, the occurrence of flying offset can be suppressed. That is, there is no case where the ink composition is not sprayed accurately on the pixel portion forming area to be sprayed, resulting in insufficient filling of the ink composition, or the ink composition is sprayed on the pixel portion forming area that should be sprayed. Adjacent pixel portions form regions (or pixel portions), and color reproducibility decreases. In addition, the surface tension described in this specification means the surface tension measured at 23 degreeC, and is what was measured by the ring method (also called a ring method).

When the ink composition is alkali-soluble, the coating film of the ink composition easily absorbs moisture in the atmosphere, so with the passage of time, the luminescent properties (such as fluorescent properties) of luminescent nanocrystals (quantum dots, etc.) ) will be gradually damaged. From this viewpoint, the ink composition is preferably an ink composition capable of forming an alkali-insoluble coating film. Such an ink composition can be obtained by using an alkali-insoluble photopolymerizable compound as the photopolymerizable compound. The so-called coating film of the ink composition is alkali-insoluble, which means that the amount of dissolution of the coating film of the ink composition at 25°C in 1 mass % potassium hydroxide aqueous solution is based on the total mass of the coating film of the ink composition. The standard is 30 mass % or less. The above-mentioned dissolved amount of the coating film of the ink composition is preferably 10% by mass or less, more preferably 3% by mass or less. Furthermore, the ink composition is an ink composition capable of forming an alkali-insoluble coating film, which can be obtained by coating the ink composition on a substrate, and then drying it at 80° C. for 3 minutes. The above-mentioned dissolved amount of the coating film having a thickness of 1 μm was confirmed.

The above-mentioned ink composition can be produced, for example, by a method including a step of mixing the constituent components of the above-mentioned ink composition. The manufacturing method of an ink composition may further comprise the process of carrying out the dispersion process of the mixture of the said component.

The method for producing an ink composition includes, for example: a first step of preparing a dispersion of light-scattering particles containing light-scattering particles; and a second step of combining the dispersion of light-scattering particles and luminescent nanoparticles Grain mix. The dispersion of light-scattering particles may further contain a polymer dispersant. In this method, the dispersion of light-scattering particles may further contain a photopolymerizable compound, and in the second step, a photopolymerizable compound may be further mixed. By the above-mentioned method, the light-scattering particles can be sufficiently dispersed. Therefore, the optical properties (eg, external quantum efficiency) of the pixel portion can be improved, and an ink composition excellent in ejection stability can be easily obtained.

In the step of preparing the dispersion of the light-scattering particles, the light-scattering particles can be prepared by mixing the light-scattering particles, a polymer dispersant, which may be present, and a photopolymerizable compound, and performing dispersion treatment. the dispersion. The mixing and dispersing treatment can be performed using a dispersing device such as a bead mill, a paint conditioner, a planetary mixer, and a jet mill. From the viewpoint that the dispersibility of the light-scattering particles becomes favorable and it is easy to adjust the average particle diameter of the light-scattering particles to a desired range, it is preferable to use a bead mill or a paint conditioner. The light-scattering particles can be more sufficiently dispersed by mixing the light-scattering particles and the polymer dispersant before mixing the light-emitting nanocrystals and the light-scattering particles. Therefore, excellent ejection stability and excellent external quantum efficiency can be further easily obtained.

The manufacturing method of an ink composition may further comprise the process of preparing the dispersion of the luminescent nanocrystal containing a luminescent nanocrystal and a photopolymerizable compound before the 2nd process. In this case, in the second step, the dispersion of light-scattering particles and the dispersion of luminescent nanocrystals are mixed. In the step of preparing the dispersion of the luminescent nanocrystals, the luminescent nanocrystal dispersion can be prepared by mixing the luminescent nanocrystals with the photopolymerizable compound and performing dispersion treatment. As the luminescent nanocrystal, a luminescent nanocrystal having an organic ligand on the surface thereof can be used. That is, the luminescent nanoparticle dispersion may further contain an organic ligand. The mixing and dispersing treatment can be carried out using a common stirring device such as an electromagnetic stirrer and a three-one motor, or a dispersing device such as a vortex mixer, a bead mill, a paint conditioner, a planetary mixer, and a jet mill. From the viewpoint of not applying excessive energy to the luminescent nanocrystals, it is preferable to use a common stirring device such as an electromagnetic stirrer, a Sany motor, or a vortex mixer. By this method, the performance of the luminescent nanocrystals can be sufficiently dispersed without deteriorating. Therefore, the optical properties (eg, external quantum efficiency) of the pixel portion can be improved, and an ink composition excellent in ejection stability can be easily obtained.

[cleaning liquid] The cleaning solution of the present embodiment is a liquid substance (such as a liquid composition), which is characterized by containing 80% by mass or more of low molecular weight compounds, and having a viscosity of 50 mPa·s or less at 25°C. The vapor pressure at 25°C is 650 Pa or less, and the logP of the above-mentioned low molecular compound is -1 to 8. A low molecular weight compound may be used individually by 1 type, and may be used in combination of a plurality of types.

With the cleaning solution of the present embodiment, the ink composition remaining in the vicinity of the flow path and nozzles of the ink jet head and the adhering matter derived from the ink composition can be removed favorably. The reason for obtaining such an effect is presumed as follows.

That is, the conventional cleaning solution for inkjet ink tends to have high volatility in order to prevent the cleaning solution from remaining in the inkjet head after cleaning. However, in the case of using such a highly volatile cleaning solution, the cleaning solution volatilizes rapidly, so the ink composition tends to adhere to the vicinity of the flow paths and nozzles of the inkjet head. In particular, when conventional cleaning solutions are used for cleaning ink compositions containing luminescent nanocrystals and photopolymerizable compounds, the components in the ink composition are in a dispersed state (such as luminescent nanocrystals). The dispersion state of rice grains and light-scattering particles) tends to be easily destroyed by the cleaning solution, and the components in the ink composition such as luminescent nanocrystals agglomerate and easily generate adhesions. Since the flow paths and nozzles of the ink jet head have a fine structure, even if a small amount of the above-mentioned adherents remains, the flow path resistance will increase, and the ejectability of the ink composition will also decrease. On the other hand, the cleaning solution of the present embodiment contains 80% by mass or more of low molecular weight compounds, and the logP of the low molecular weight compounds is -1 to 8. Therefore, when the cleaning solution of the present embodiment is used, the above-mentioned dispersion damage is unlikely to occur. . In addition, since the vapor pressure of the low-molecular-weight compound at 25°C is 650 Pa or less, by using the cleaning solution of this embodiment, rapid volatilization of the cleaning solution can be suppressed. The viscosity at 25°C is 50 mPa·s or less, so it can suppress the increase in the resistance of the flow path when it comes into contact with the ink composition. Therefore, even if a local dispersion failure occurs, it is difficult for the aggregate to remain. The inventors of the present invention speculate that the above-mentioned effects are obtained for such reasons.

The viscosity of the cleaning solution at 25°C is preferably 30 mPa·s or less, more preferably 20 mPa·s or less, from the viewpoint of better fluid permeability of the cleaning solution when it comes into contact with the ink composition. From the viewpoint of cleaning properties, the viscosity of the cleaning solution at 25°C is preferably 2 mPa·s or more. In addition, the said viscosity is the value measured using the E-type viscometer.

Low molecular weight compounds are organic compounds whose molecular weight is less than 750. The molecular weight of the low-molecular-weight compound is preferably 500 or less in terms of easily obtaining an appropriate viscosity. The molecular weight of the low molecular weight compound is preferably 50 or more, and more preferably 100 or more, from the viewpoint that the volatility does not become too high.

The vapor pressure of the low-molecular compound at 25°C is preferably 500 Pa or less, more preferably 400 Pa or less, from the viewpoint of more easily suppressing the rapid volatilization of the cleaning solution to generate adhesions from the ink composition. The vapor pressure of the low molecular compound at 25°C is, for example, 0.00001 Pa or more. In addition, the vapor pressure is recorded and described in SciFinder (Chemical Abstracts Service, an online search service of the American Chemical Society).

The logP of the low-molecular-weight compound is preferably 0 or more, more preferably 1 or more, from the viewpoint of being less likely to cause dispersion damage during washing. The logP of the low molecular weight compound is preferably 6 or less, more preferably 5 or less, from the viewpoint of easier maintenance of the dispersed state of the components in the ink composition during washing. From these viewpoints, the logP of the low molecular weight compound is preferably 0-6, more preferably 1-5. logP was obtained from SciFinder (Chemical Abstracts Service, an online search service of the American Chemical Society).

From the viewpoint of easily adjusting the viscosity of the cleaning solution to the above range, the viscosity of the low molecular compound at 25°C is preferably 50 mPa·s or less, more preferably 30 mPa·s or less, and still more preferably 20 mPa·s. s or less. The viscosity of the low molecular weight compound at 25°C is preferably 1 mPa·s or more from the viewpoint of easily adjusting the viscosity of the cleaning solution to the above range. The viscosity of the low molecular weight compound can be measured in the same manner as the viscosity of the cleaning solution.

Since organic compounds with a PII value of 3 or more are highly irritating to the human body, the PII value of the low molecular weight compound is preferably less than 3, more preferably 2 or less, and still more preferably 1 or less. It is preferable that the cleaning liquid does not substantially contain an organic compound having a PII value of 3 or more.

The low molecular weight compound is preferably a compound having an ethylenically unsaturated group from the viewpoint of being easily compatible with the photopolymerizable compound in the ink composition and more easily maintaining the dispersed state of the components in the ink composition. A compound having a methacryloyl group is preferable, and a monofunctional or polyfunctional methacrylate is more preferable. However, from the viewpoint that the viscosity does not become too high, it is preferable that the low molecular weight compound does not have an acryl group.

As a low molecular weight compound, in addition to the above-mentioned compounds (for example, a monofunctional monomer, a difunctional monomer, and a trifunctional monomer) exemplified as the photopolymerizable compound, for example, ethylene glycol monobutyl ether acetate may, for example, be mentioned. , diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol dibutyl ether, tripropylene glycol monomethyl ether, diethyl adipate , Dibutyl oxalate, Dimethyl malonate, Diethyl malonate, Dimethyl succinate, Diethyl succinate, 1,4-Butanediol diacetate, Glyceryl triacetate, Carbonic acid Acrylate, phenoxyethanol, benzyl alcohol, etc. Among them, at least one selected from the group consisting of phenoxyethyl methacrylate, 1,6-hexanediol dimethacrylate, and propylene glycol monomethyl ether acetate is suitably used.

The content of the low-molecular-weight compound is preferably 85% by mass or more based on the total mass of the cleaning solution from the viewpoint of easily obtaining the cleaning solution. The content of the low molecular weight compound may be 100 mass % or less, 95 mass % or less, or 90 mass % or less based on the total mass of the cleaning liquid.

The cleaning solution may contain a dispersant. By containing the dispersant in the cleaning solution, it becomes easier to suppress the dispersion and destruction of the ink composition caused by the cleaning solution. The dispersant may be a dispersant with a molecular weight of 30,000 or less. The dispersant is preferably a dispersant having a molecular weight of 750 or more.

As the dispersant, a compound known as a pigment dispersant can be used, and a polymer dispersant described as a component that can be included in the ink composition can also be used. As the dispersant, when the ink composition contains light-scattering particles, the above-mentioned polymer dispersant is preferably used, and the same polymer dispersant as the polymer dispersant contained in the ink composition is more preferably used.

From the viewpoint of more easily suppressing the dispersion destruction of the ink composition, the content of the dispersant is based on the total mass of the cleaning solution, preferably 1 mass % or more, more preferably 2 mass % or more, and more preferably 3 mass % or more. The content of the dispersant may be 20% by mass or less, or 15% by mass or less, based on the total mass of the cleaning liquid. In this embodiment, it is preferable that the content of the dispersing agent having a molecular weight of 750 or more is within the above-mentioned range.

The cleaning solution may contain a surface conditioner. By adding a surface conditioner to the cleaning solution, the surface tension of the cleaning solution is reduced, and the cleaning solution can easily penetrate into the interface between the ink composition, the flow channel and the nozzle opening, and the cleaning performance is improved.

As the surface conditioning agent, for example, a polyether-modified polysiloxane-based surface conditioning agent, an aralkyl-modified polysiloxane-based surface conditioning agent, a fluorine-based surface conditioning agent, and the like can be used. Among them, polyether-modified polysiloxane-based surface conditioners are suitably used. As the surface conditioner, the modified polysiloxanes described as components that can be included in the ink composition can also be used.

From the viewpoint of further reducing the surface tension of the cleaning solution, the content of the surface conditioner is based on the total mass of the cleaning solution, preferably 0.5% by mass or more, more preferably 1% by mass or more, and still more preferably 2 mass % or more. The content of the surface conditioner may be 10 mass % or less, 5 mass % or less, or 3 mass % or less based on the total mass of the cleaning liquid.

The cleaning liquid may further contain components other than organic compounds (eg, water, etc.). However, from the viewpoint of suppressing deactivation of the luminescent nanocrystals, the water content of the cleaning solution is preferably 6000 mass ppm or less, more preferably 3000 mass ppm or less, and still more preferably 1000 mass ppm or less.

The cleaning solution is preferably substantially free of compounds that deactivate the luminescent nanocrystals, such as peroxides, so as not to impair the functionality of the luminescent nanocrystals. The so-called cleaning solution does not substantially contain peroxide, refers to the measurement of the cleaning solution when adding 5% by volume of potassium iodide ethanol solution (3% by weight) to the cleaning solution with an optical path length of 1 cm using a UV-Vis spectrophotometer. The absorption spectrum of the clean liquid has no absorption around 400-450 nm (absorbance is below 0.1). In addition, from the viewpoint of suppressing the generation of peroxides stored for a long time, the cleaning solution preferably does not contain a compound having a polyalkylene glycol chain such as a PEG chain or a PPG chain. The content of the compound having a polyalkylene glycol chain is based on the total mass of the cleaning solution, for example, 5 mass % or less (preferably 0 mass %).

From the viewpoint that the cleaning solution easily penetrates into the interface between the ink composition, the flow channel and the nozzle opening, and the cleaning performance is further improved, the surface tension of the cleaning solution at 25°C is preferably 50 mN/m or less, more preferably 50 mN/m or less. 45 mN/m or less, more preferably 40 mN/m or less. From the viewpoint of suppressing osmotic damage to the flow path and nozzle opening, the surface tension of the cleaning solution at 25°C is preferably 5 mN/m or more, more preferably 10 mN/m or more, and more preferably 15 mN/m above. In addition, the said surface tension is the value measured by the ring method (also called the ring method).

From the viewpoint of suppressing deactivation of the luminescent nanocrystals, the dissolved oxygen concentration of the cleaning solution is preferably 7 mass ppm or less. That is, in the cleaning step, it is preferable to set the dissolved oxygen concentration of the cleaning solution at the time of cleaning to 7 mass ppm or less. The dissolved oxygen concentration of the cleaning liquid is more preferably 5 mass ppm or less, and still more preferably 4 mass ppm or less. The dissolved oxygen concentration of the cleaning solution can be adjusted by changing the temperature, pressure, etc. of the cleaning solution when performing the cleaning step. In addition, the said dissolved oxygen concentration is the value measured using a dissolved oxygen concentration meter.

The cleaning solution described above can be prepared by mixing the above components (low molecular compound, dispersant, surface conditioner, etc.).

Next, each step in the printing method of the present embodiment will be described. In the following description, "ink composition" and "cleaning liquid" refer to the above-described ink composition of this embodiment and the cleaning liquid of this embodiment.

[1st ejection step] In the first ejection step, the ink composition is ejected from the head (inkjet head) of the inkjet printing apparatus. Thereby, a printed matter containing the ink composition or its dried product is formed. The first ejection step refers to the printing step immediately preceding the cleaning step. Therefore, when the second cleaning step is performed after the cleaning step is performed once, it refers to the printing step immediately before the second cleaning step. The printing step can be performed continuously or intermittently.

Specifically, the inkjet printing device may be a continuous type or an on-demand type, but from the viewpoint that the effects of the present invention can be remarkably obtained, an on-demand type is preferred . Instant printing is a method of ejecting the required amount of ink droplets during printing, and the ink supply after ejection will utilize the capillary phenomenon. Therefore, when the conventional printing method is applied to the print-on-demand inkjet printing device, there is a tendency that the ink composition of the present embodiment has a tendency to have poor ejection. However, in the printing method of the present embodiment, even when using In the case of a ready-to-print inkjet printing device, the occurrence of ejection failure can also be suppressed, and the occurrence of thickness variation of the light conversion layer can be suppressed.

As a printing method of a print-on-demand inkjet printing apparatus, a bubble inkjet (registered trademark) method using an electrothermal transducer as an energy generating element, or a piezoelectric inkjet method using a piezoelectric element, etc., can be exemplified. Among them, an ink jet printing apparatus using a piezoelectric ink jet method is preferred, which utilizes a mechanical ejection mechanism using a piezoelectric element. In the piezoelectric inkjet method, the ink composition is not instantaneously exposed to high temperature during ejection. Therefore, the deterioration of the luminescent nanocrystals is less likely to occur, and the pixel portion (light conversion layer) is more likely to obtain desired luminescent properties.

The inkjet head includes a plurality of nozzles and a flow path for supplying the ink composition to the nozzles. A plurality of nozzles are formed in, for example, a nozzle plate provided in the ink jet head. The ink composition is supplied to the nozzle through the flow path in the ink jet head, and is ejected from an opening (discharge port) provided at one end of the nozzle.

The ejection time and ejection amount of the ink composition are not particularly limited. For example, in the case of performing regular cleaning, if the cleaning step is performed every day at the end of the operation of the printing press or at the start of the operation of the next day, the ejection time is several hours. On the other hand, in the case of long-term operation of 24-hour operation, or the case of intermittent long-term operation of several days or months, the ink composition can be continuously ejected until the occurrence of ejection failure is confirmed. In this case, the cleaning step can be performed at the time when the ejection failure of the ink composition is confirmed.

[washing step] In the cleaning step, the inkjet head is cleaned with a cleaning solution. Thereby, the ink composition in the flow path in the inkjet head and the vicinity of the nozzle (such as the inner wall of the nozzle and the periphery of the ejection port of the nozzle plate) and the adhering matter from the ink composition are removed.

The cleaning of the inkjet head can be performed by, for example, filling the ink supply system of the inkjet printing apparatus with a cleaning liquid, and using a diaphragm pump or the like to send liquid and/or pressurize, a water level difference, etc., to remove the cleaning liquid. The clean liquid is filled into the inkjet head and discharged from the nozzle. In the case where the ink is discharged by pressing, the pressing force is preferably 1 kPa to 50 kPa, more preferably 5 kPa to 30 kPa. In addition, the nozzle plate can also be washed more cleanly by wiping the nozzle plate (especially the periphery of the ejection port) with "non-woven cloth containing cleaning liquid, etc.". In addition, the cleaning method is not limited to the above-mentioned method, and a cleaning method recommended in the inkjet printing apparatus and inkjet head to be used may be applied.

The amount of the cleaning solution to be used is not particularly limited, and can be appropriately set according to the size of the object to be cleaned, the amount of ink composition remaining in the ink jet head, and the amount of adhered matter. The temperature of the cleaning solution may be, for example, 20 to 50°C. The temperature of the cleaning solution can be adjusted according to the temperature of the inkjet head.

[Second ejection step] The second ejection step is a step of ejecting the ink composition from the inkjet head similarly to the first ejection step, and refers to the printing step immediately following the cleaning step. Therefore, when the second cleaning step is performed next, it becomes the first ejection step with respect to the second cleaning step. As described above, in the present invention, the quality of the printed matter formed by the second ejection step is remarkably excellent. At this time, the ink composition used may be the same as or different from the ink composition used in the first ejection step.

[pause step] The printing method of the present embodiment may include a pause step in which printing (ejection of the ink composition) is not performed for a long time (eg, 6 hours or more) between the first ejection step and the second ejection step. The suspending step may be, for example, a step for maintaining the inkjet printing device, or a step for suspending the process at night or the like. In the case of implementing such a suspension step, the thickness of the light conversion layer produced by printing after the suspension step is prone to change. However, by performing the above cleaning step before the suspension step or after the suspension step (preferably before the suspension step) , the thickness variation of the light conversion layer can be suppressed.

In the printing method of the present embodiment, after the second discharge step, the cleaning step may be performed again as described above. After the cleaning step, the above-mentioned spraying step, the optional pause step, and the cleaning step may be repeatedly performed.

<Method of forming light conversion layer> A method of forming a light conversion layer according to an embodiment includes: a step of printing the ink composition of the above-described embodiment by the printing method of the above-described embodiment; The printed matter) is irradiated with light (active energy rays) to harden the ink composition of the above embodiment. Thereby, the light conversion layer containing the hardened|cured material of the ink composition of the said embodiment is obtained.

The light conversion layer is, for example, a light conversion layer constituting a color filter. In this case, the cured product of the ink composition of the above-described embodiment constitutes the color filter pixel portion.

Hereinafter, the light conversion layer constituting the color filter and the formation method thereof will be exemplified, and the formation method of the light conversion layer of the present embodiment will be described. In addition, in the following description, the same code|symbol is used for the same or equivalent element, and the repeated description is abbreviate|omitted. In addition, in the following description, the ink composition of the said embodiment is called a luminescent ink composition, and the non-luminescent ink composition which does not contain a luminescent nanocrystal is called a non-luminescent ink composition. The non-luminescent ink composition may be a conventionally known ink composition, and has the same composition as the ink composition (luminescent ink composition) of the above-described embodiment except that it does not contain luminescent nanocrystals.

FIG. 1 is a schematic cross-sectional view of a color filter having a light conversion layer according to an embodiment. As shown in FIG. 1 , the color filter 100 includes a base material 40 and a light conversion layer 30 provided on the base material 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 10 a , a second pixel portion 10 b , and a third pixel portion 10 c as the pixel portion 10 . The 1st pixel part 10a, the 2nd pixel part 10b, and the 3rd pixel part 10c are arrange|positioned in a lattice shape so that it may repeat in 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 third pixel portion 10c. 1 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 light-emitting pixel portions (light-emitting pixel portions) containing a cured product of the above-described ink composition, respectively. The 1st pixel part 10a contains the 1st hardening component 13a, and the 1st luminescent nanocrystal 11a and the 1st light-scattering particle 12a which were respectively dispersed in the 1st hardening component 13a. Similarly, the 2nd pixel part 10b contains the 2nd hardening component 13b, and the 2nd luminescent nanocrystal 11b and the 2nd light-scattering particle 12b which are respectively dispersed in the 2nd hardening component 13b. The hardening component is a component obtained by polymerization of a photopolymerizable compound, and includes a polymer of a photopolymerizable compound. In addition to the above-mentioned polymers, the curing component may contain organic components (organic ligands, polymer dispersants, unreacted polymerizable compounds, etc.) contained in the ink composition. In the first pixel portion 10a and the second pixel portion 10b, the first hardening component 13a and the second hardening 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, can be different.

The first luminescent nanocrystal 11a is a red luminescent nanocrystal that absorbs light with a wavelength in the range of 420 to 480 nm and emits light with an emission peak wavelength in the range of 605 to 665 nm. That is, in other words, the first pixel portion 10a is a red pixel portion for converting blue light into red light. In addition, the second luminescent nanocrystal 11b is a green luminescent nanocrystal that absorbs light having a wavelength in the range of 420 to 480 nm and emits light having an emission peak wavelength in the range of 500 to 560 nm. That is, in other words, the second pixel portion 10b is a green pixel portion for converting blue light into green light.

From the viewpoint of having a more excellent effect of improving the external quantum efficiency and obtaining an excellent luminous intensity, the content of the luminescent nanocrystals in the luminescent pixel portion is based on the total mass of the cured product of the luminescent ink composition In total, it is preferably 10% by mass or more, and may be 20% by mass or more, 22% by mass or more, 24% by mass or more, or 26% by mass or more. From the viewpoint of excellent reliability of the pixel portion and from the viewpoint of obtaining excellent luminous intensity, the content of the luminescent nanocrystals is based on the total mass of the cured product of the luminescent ink composition, preferably 80 mass % or less, and may be 70 mass % or less, 60 mass % or less, 50 mass % or less, or 40 mass % or less.

From the viewpoint that the effect of improving the external quantum efficiency is more excellent, the content of the light-scattering particles in the light-emitting pixel portion is based on the total mass of the cured product of the light-emitting ink composition, for example, 0.1% by mass or more, or It may be 1 mass % or more or 2 mass % or more. The content of the light-scattering particles is based on the total mass of the cured product of the luminescent ink composition, and is, for example, 60% by mass or less. The content of the light-scattering particles is based on the total mass of the cured product of the luminescent ink composition, and is preferably 10 mass from the viewpoint that the effect of improving the external quantum efficiency is more excellent and the reliability of the pixel portion is excellent. % or less, more preferably 7 mass % or less, still more preferably 5 mass % or less.

The third pixel portion 10c is a non-luminescent pixel portion (non-luminescent pixel portion) including a cured product of the non-luminescent ink composition. The cured product does not contain light-emitting nanocrystal grains, but contains light-scattering particles and curing components. That is, the 3rd pixel part 10c contains the 3rd hardening component 13c, and the 3rd light-scattering particle 12c dispersed in the 3rd hardening component 13c. The 3rd hardening component 13c is a component obtained by superposing|polymerizing a polymerizable compound, for example, and contains the polymer of a polymerizable compound. The 3rd light-scattering particle 12c, the 1st light-scattering particle 12a, and the 2nd light-scattering particle 12b may be the same, and may differ.

The third pixel portion 10c has, for example, a transmittance of 30% or more for light having a wavelength in the range of 420 to 480 nm. Therefore, the third pixel portion 10c functions as a blue pixel portion when a light source emitting light having a wavelength in the range of 420 to 480 nm is used. In addition, the transmittance of the 3rd pixel part 10c can be measured by the microspectroscopy apparatus.

From the viewpoint of further reducing the light intensity difference at the viewing angle, the content of the light-scattering particles in the non-luminescent pixel portion may be 1 mass % based on the total mass of the cured product of the non-luminescent ink composition. More than 5 mass % or more may be sufficient, and 10 mass % or more may be sufficient. From the viewpoint of further reducing light reflection, the content of the light-scattering particles may be 50% by mass or less, or 30% by mass or less, based on the total mass of the cured product of the non-luminescent ink composition. It may be 20 mass % or less.

The thickness of the pixel portion (the first pixel portion 10a, the second pixel portion 10b, and the third pixel portion 10c) may be, for example, 1 μm or more, 2 μm or more, or 3 μm or more. 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, 30 μm or less, 20 μm or less, or 15 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 fine particles, metal oxides, inorganic pigments, and organic pigments in the binder polymer can also be used. Wait. As the binder polymer used here, one or two or more kinds of polyimide resin, acrylic resin, epoxy resin, polyacrylamide, polyvinyl alcohol, gelatin, casein, cellulose, etc. can be used Resin mixtures, photosensitive resins, O/W emulsion resin compositions (for example, those obtained by emulsification of reactive polysiloxane), etc. The thickness of the light shielding portion 20 may be, for example, 0.5 μm or more and 10 μm or less.

The base material 40 is a transparent base material with light transmittance, for example, transparent glass substrates such as quartz glass, Pyrex (registered trademark) glass, synthetic quartz plate, etc., and transparent flexible base materials such as transparent resin films and optical resin films can be used Wait. Among these, it is preferable to use the glass substrate which consists of alkali-free glass which does not contain an alkali component in glass. Specifically, "7059 glass", "1737 glass", "Eagle 200" and "Eagle XG" manufactured by Corning Corporation, "AN100" manufactured by Asahi Glass Co., Ltd., "OA-10G" manufactured by Nippon Electric Glass Co., Ltd. and "OA-11". It is a material with a low coefficient of thermal expansion, and is excellent in dimensional stability and workability during high-temperature heat treatment.

The color filter 100 provided with the above light conversion layer 30 is suitable for use in the case of using a light source that emits light having a wavelength in the range of 420 to 480 nm.

The light conversion layer 30 can be formed by a method including the following steps: a printing step in which the luminescent ink composition is printed on the pixel portion forming region by the printing method of the above-mentioned embodiment, and the pixel portion forming region is formed by having a luminescent ink composition. The light-shielding portion 20 on the base material 40 of the light-shielding portion 20 formed in a pattern is divided; and the curing step is to cure the luminescent ink composition by irradiating light (active energy rays) to the obtained printed matter.

In the printing step, the luminescent ink composition ejected in the first ejection step and the luminescent ink composition ejected in the second ejection step selectively adhere to the pixel portion forming region on the substrate 40 . When the light-emitting ink composition adhered to the pixel portion forming region contains an organic solvent, the organic solvent can be removed from the light-emitting ink composition by drying. Thereby, the printed matter containing the luminescent nanocrystal, a photopolymerizable compound, and the arbitrary components other than the said organic solvent exists as the case may be obtained.

The drying of the luminescent ink composition only needs to remove at least a part of the organic solvent, and preferably all the organic solvent is removed. The drying method of the luminescent ink composition is preferably drying under reduced pressure (drying under reduced pressure). From the viewpoint of controlling the composition of the luminescent ink composition, drying under reduced pressure is usually carried out at 20 to 30° C. for 3 to 30 minutes under a pressure of 1.0 to 500 Pa.

In the curing step, by curing the luminescent ink composition (or the luminescent ink composition after drying) contained in the printed matter, a luminescent pixel portion of a cured product containing the luminescent ink composition is obtained.

For curing of the luminescent ink composition, for example, a mercury lamp, a metal halide lamp, a xenon lamp, and an LED can be used. The wavelength of the light to be irradiated may be, for example, 200 nm or more and 440 nm or less. The exposure amount may be, for example, 10 mJ/cm ² or more and 20000 mJ/cm ² or less.

The hardening step can also be carried out in the middle of the printing step. For example, after the first discharge step and before the second discharge step, a curing step may be performed on the printed matter printed by the first discharge step. In this case, the hardening step is performed on the printed matter printed by the second discharge step after the second discharge step.

The method of forming the light conversion layer 30 may further include the step of forming a non-luminescent pixel portion. The non-luminescent pixel portion can be formed in the same manner as the luminescent pixel portion except that a non-luminescent ink composition is used instead of the luminescent ink composition.

The method of forming the light conversion layer 30 may further include the step of forming the light shielding portion 20 . As a method of forming the light-shielding portion 20 , a thin film of a metal such as chromium or a thin film of a resin composition containing light-shielding particles may be formed in a region on one surface side of the substrate 40 that serves as a boundary between a plurality of pixel portions, and the The method of patterning the thin film, etc. The metal thin film can be formed by, for example, a sputtering method, a vacuum deposition method, or the like, and the film of the resin composition containing light-shielding particles can be formed by, for example, methods such as coating and printing. As a method of performing patterning, photolithography etc. are mentioned.

As mentioned above, although the printing method and the formation method of the light conversion layer of this embodiment were demonstrated, this invention is not limited to the said method.

For example, one aspect of the present invention can also be described as the cleaning solution related to the above-described embodiment. In addition, for example, one aspect of the present invention can also be described as a method for cleaning an inkjet head, the method comprising the steps of: ejecting a liquid containing luminescent nanocrystals, and After the ink composition for forming the light conversion layer of the photopolymerizable compound (for example, the ink composition of the above-mentioned embodiment), the ink jet head is cleaned.

In addition, the light conversion layer and the color filter which can be formed by this invention are not limited to the light conversion layer and the color filter demonstrated above.

For example, the light conversion layer may include a pixel portion (blue pixel portion) including a cured product of a light-emitting ink composition containing blue light-emitting nanocrystals instead of the third pixel portion 10c, or in addition to the third pixel portion In addition to 10c, a pixel portion (blue pixel portion) including a cured product of a light-emitting ink composition containing blue light-emitting nanocrystals is provided. In addition, the light conversion layer may include a pixel portion (eg, a yellow pixel portion) including a cured product of the luminescent ink composition containing nanocrystals that emit light of colors other than red, green, and blue. In such cases, each of the luminescent nanocrystals contained in each pixel portion of the light conversion layer preferably has a maximum absorption wavelength in the same wavelength region.

Moreover, at least a part of the pixel part of a light conversion layer may contain the hardened|cured material of the composition containing a pigment other than a luminescent nanocrystal.

In addition, the color filter may include, on the pattern of the light-shielding portion, an ink-repellent layer made of a material having ink-repellent properties, which is narrower in width than the light-shielding portion. In addition, the ink repellent layer may not be provided, and after the area including the pixel portion formation area is covered with the photocatalyst-containing layer as the wettability variable layer, the photocatalyst-containing layer is irradiated with light through a light shield to expose the photocatalyst-containing layer. The ink affinity of the pixel portion formation region is increased significantly. As a photocatalyst, titanium oxide, zinc oxide, etc. are mentioned.

In addition, the color filter may include an ink-receiving layer including hydroxypropyl cellulose, polyvinyl alcohol, gelatin, or the like between the substrate and the pixel portion.

In addition, the color filter may include a protective layer on the pixel portion. This protective layer is provided in order to flatten the color filter and prevent the components contained in the pixel portion, or the components contained in the pixel portion and the components contained in the photocatalyst-containing layer from being eluted into the liquid crystal layer. As the material constituting the protective layer, a known protective layer for color filters can be used.

Furthermore, in the pixel portion of the light conversion layer of the present embodiment, in addition to the above-mentioned luminescent nanocrystals, a pigment having substantially the same color as that of the luminescent nanocrystals may be further contained. In order to contain a pigment in a pixel part, you may contain a pigment in a luminescent ink composition.

In addition, one or two types of luminescent pixel portions among 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 set to be different. A pixel portion containing a luminescent nanocrystal and a colored material. As the colored material that can be used here, a known colored material can be used, and for example, as the colored material used for the red pixel portion (R), a diketopyrrolopyrrole pigment and/or an anionic red organic dye can be exemplified. The colored material used for the green pixel portion (G) may, for example, be selected from the group consisting of a copper halide phthalocyanine pigment, a phthalocyanine-based green dye, a mixture of a phthalocyanine-based blue dye, and an azo-based yellow organic dye. at least one of them. As the colored material used for the blue pixel portion (B), an epsilon-type copper phthalocyanine pigment and/or a cationic blue organic dye can be exemplified. The amount of these colored materials to be used when contained in the light conversion layer is based on the total mass of the pixel portion (hardened product of the ink composition) from the viewpoint of preventing a decrease in transmittance. Preferably it is 1-5 mass %.

In addition, the color filter may include a normal color filter layer that does not contain luminescent nano-chips and contains the above-mentioned colored material between the base material and the pixel portion of the present embodiment. That is, the color filter of the present embodiment may include a substrate, a color filter layer provided on the substrate that does not contain luminescent nanoparticles but contains a colored material, and the present embodiment provided on the color filter layer The pixel part of the method. [Example]

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following examples. In addition, all the materials used in the examples were made by introducing argon gas and replacing the dissolved oxygen with argon gas. As for the titanium oxide, one heated at 175° C. under a reduced pressure of 1 mmHg for 4 hours before mixing and left to cool under an argon atmosphere was used. The liquid materials used in the examples were dehydrated by molecular sieve 3A for more than 48 hours before mixing.

<Preparation of QD Particles with Organic Ligand (QD Powder)> [Synthesis of Organic Ligand 1] Polyethylene glycol |average Mn350| (manufactured by Sigma-Aldrich) was put into a flask, and then placed in a nitrogen atmosphere Next, while stirring, an equimolar amount of succinic anhydride (manufactured by Sigma-Aldrich) and polyethylene glycol|average Mn350| was added thereto. The internal temperature of the flask was raised to 80°C, and the mixture was stirred for 8 hours, thereby obtaining the organic ligand 1 represented by the following formula (A) in the form of a pale yellow viscous oil.

[Production of QD powder using ligand exchange] Add 2.0 times the amount of PGMEA (propylene glycol) to InP nanocrystalline dispersion manufactured by Nanosys (InP QD in Heptane Red InP QD, QD particle (luminescent nanoparticle) concentration 30%, organic ligand: oleic acid) Monomethyl ether acetate), and the organic ligand 1 in an amount corresponding to 40% by mass relative to the QD particles (the amount excluding the organic ligand), and the coordination was carried out by stirring at 80° C. for 1 hour. body exchange. The QD particles were agglomerated by adding 4 times the amount of heptane to the solution and precipitated by centrifugation, and then the QD particles were separated by pouring the supernatant. The obtained QD particles were dried with a vacuum dryer to obtain QD powder 1 (QD particles/organic ligand=75 mass %/25 mass %).

<Preparation of Light Scattering Particle Dispersion> In a container filled with argon gas, 5.23 g of titanium oxide (product name: CR-60-2, manufactured by Ishihara Sangyo Co., Ltd., average particle diameter (volume average diameter): 210 nm), polymer dispersant (Ajisper PB -821, manufactured by Ajinomoto Fine-Techno Co., Ltd.) 0.27 g, and HDDM (1,6-hexanediol dimethacrylate, product name: Lightester 1.6HX, manufactured by Kyoeisha Chemical Co., Ltd.) 4.5 g were mixed Then, zirconia beads (diameter: 1.25 mm) were added to the obtained mixture, and the mixture was subjected to a dispersion treatment by shaking with a paint conditioner for 2 hours, and the zirconia beads were removed with a polyester mesh filter, thereby obtaining Light-scattering particle dispersion 1 (titanium oxide content: 55 mass %).

<Preparation of ink composition and evaluation of physical properties> [Ink composition 1: QD low concentration (less than 10% by mass)] Mix 5 g of QD powder 1, 1 g of light-scattering particle dispersion 1, 3 g of photopolymerization initiator (phenyl(2,4,6-trimethylbenzyl)-diphenylene Phosphine oxide, manufactured by IGM resin, product name: Omnirad TPO, and 91 g of a photopolymerizable component (PhEM (phenoxyethyl methacrylate, product name: Lightester PO, Kyoeisha Chemical Co., Ltd.) Manufacturing): LM (Lauryl methacrylate, product name: Lightester L, manufactured by Kyoeisha Chemical Co., Ltd.): HDDM=47:21:32 (mass ratio)), uniformly carried out in a container filled with argon gas After mixing, the mixture was filtered through a filter with a pore size of 5 μm in a glove box. Furthermore, argon gas was introduced into the container containing the obtained filtrate, and the container was saturated with argon gas. Next, the pressure was reduced to remove the argon gas, whereby the ink composition 1 (inkjet ink) was obtained.

[Ink composition 2: QD high concentration (10 mass % or more)] Mix 30 g of QD powder 1, 5 g of light-scattering particle dispersion 1, 3 g of photopolymerization initiator (phenyl(2,4,6-trimethylbenzyl)-diphenylene oxy-phosphine oxide, manufactured by IGM resin company, product name: Omnirad TPO), and 62 g of photopolymerizable component (PhEM:LM:HDDM=47:21:32 (mass ratio)) in a container filled with argon gas After mixing uniformly, the mixture was filtered through a filter with a pore size of 5 μm in a glove box. Furthermore, argon gas was introduced into the container containing the obtained filtrate, and the container was saturated with argon gas. Next, the pressure was reduced to remove the argon gas, whereby the ink composition 2 (inkjet ink) was obtained.

[Evaluation of coating film properties] Using the ink composition 2, a sample for evaluation was prepared. Specifically, the ink composition 2 was applied on a glass substrate with a spin coater in the atmosphere so as to have a film thickness of 15 μm. In a nitrogen atmosphere, the coating film was cured by irradiating UV with a UV irradiation device using an LED lamp with a dominant wavelength of 395 nm so as to achieve a cumulative light intensity of 10,000 mJ/cm ² , and the oxygen concentration was 1 vol% or less. Heating at 180°C for 30 minutes in a glove box, a layer (light conversion layer) composed of the hardened product of the ink composition was formed on the glass substrate. Thereby, the sample for evaluation was obtained.

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

From the spectrum and illuminance measured by the above-mentioned measuring apparatus, the external quantum efficiency was obtained as follows. The external quantum efficiency is a value indicating the ratio of the degree to which light (photons) incident on the light conversion layer is emitted to the observer side in the form of fluorescence. Therefore, the larger the value, the more excellent the light-emitting properties of the light conversion layer, which is an important evaluation index. EQE (%) = [P1 (red)]/E (blue) × 100

Here, E (blue) and P1 (red) represent the following, respectively. E (blue): Indicates the total value of "illuminance × wavelength÷hc" in the wavelength region of 380 to 490 nm. P1 (red): Indicates the total value of "illuminance × wavelength÷hc" in the wavelength region of 590 to 780 nm. Its equivalence system corresponds to the value of the number of photons observed. Furthermore, h represents Planck's constant, and c represents the speed of light.

The EQE of the evaluation sample (light conversion layer) produced from the ink composition 2 was 35%.

<Example> [Preparation of cleaning solution] The cleaning solutions 1 to 13 shown in Tables 1 and 2 were prepared. As low molecular weight compounds, phenoxyethyl methacrylate (PhEM), 1,6-hexanediol dimethacrylate (HDDMA), propylene glycol monomethyl ether acetate (PEGMEA), and tripropylene glycol monomethyl ether were used (TPM), isopropyl alcohol (IPA), and triethylene glycol (TEG), and as dispersants, Solsperse 71000 (product name) manufactured by Lubrizol Corporation was used. Furthermore, none of the cleaning solutions 1 to 13 contained peroxide. In addition, regarding the cleaning solutions 1 to 11, the surface tension and the water content of the cleaning solutions were measured, and it was confirmed that the surface tension was 50 mN/m or less, and the water content was 6000 mass ppm or less. Table 3 shows the logP of the low molecular weight compounds used in the cleaning solution and the vapor pressure at 25°C.

[Table 1] cleaning solution 1 cleaning solution 2 cleaning solution 3 cleaning solution 4 cleaning solution 5 cleaning solution 6 cleaning solution 7 low molecular compound PhEM 100 - 50 97 - 47.5 73 HDDMA 100 50 - 97 47.5 PEGMEA twenty four Dispersant - - - 3 3 3 3 Viscosity@25℃（Pa・s） 7.3 5.6 6.3 10.2 7.4 8.6 5.6

[Table 2] cleaning solution 8 cleaning solution 9 cleaning solution 10 cleaning solution 11 cleaning solution 12 cleaning solution 13 low molecular compound PGMEA 100 - 97 - - - TPM - 100 - 97 - - IPA - - - - 100 - TEG - - - - - 100 Dispersant - - 3 3 - - Viscosity@25℃（Pa・s） 1.1 5.3 1.4 7.1 2 45

[table 3] PhEM HDDMA PGMEA TPM IPA TEG logP 2.79 3.74 0.48 0.1 0.17 -1.65 Vapor pressure@25℃（Pa） 0.08 0.017 417 0.12 10839 0.038

The viscosity of the cleaning solution was measured with an E-type viscometer at 25°C. In addition, the logP of a low molecular weight compound used the value recorded in Scifinder (Chemical Abstracts Service, the online search service of American Chemical Society). In addition, the vapor pressure of a low molecular weight compound used the value recorded in Scifinder (Chemical Abstracts Service, the online search service of American Chemical Society).

[Evaluation of liquid permeability] In the cleaning step, the ink is diluted by the cleaning solution, which sometimes causes dispersion failure and generation of stickers. In order to evaluate the degree of adhesion generation in this cleaning step, the liquid permeability of the ink diluted with the cleaning solution was evaluated. Since the adhesion will reduce the liquid permeability, the better the liquid permeability, the less adhesion is produced. A diluted solution obtained by diluting the ink composition 10 times with the cleaning solution was prepared with the combination of the ink composition and the cleaning solution shown in Table 4. With respect to the obtained diluent, the liquid permeability of the diluent was evaluated immediately after preparation and one month after preparation. The liquid flow conditions and evaluation criteria are shown below, and Table 4 shows the evaluation results. (liquid flow condition) ・Filter: Polypropylene filter Φ25 mm pore size 0.6 μm (manufactured by Nihon Pall Co., Ltd.) ・Liquid volume: 50 ml ・Pressure pressure for liquid flow: 0.1 MPa (Evaluation Criteria) A: All liquids can pass through B: More than 90% and less than 100% of the liquid can pass through C: More than 70% and less than 90% of the liquid can pass through D: Less than 70% of the liquid can pass through

[Evaluation of cleaning properties] The cleaning properties of the cleaning solution were evaluated by the combination of the ink composition and the cleaning solution shown in Table 4. Specifically, first, the ink composition was ejected using the following inkjet printing apparatus. (ink jet condition) ・Inkjet printing device: Device Printer NM1 (manufactured by MICROJET) ・Inkjet head: KM1024iMHE-D (manufactured by Konica Minolta)

Next, the inkjet head was cleaned with a cleaning solution, and the ink composition was ejected again using the above-described inkjet printing apparatus. The cleaning with the cleaning solution is performed under the following conditions. (washing condition) ・Liquid volume: 200 ml ・Fluid pressure: 20 kpa

The cleaning performance of the cleaning solution was evaluated based on the ejection performance of the ink composition after cleaning. The evaluation criteria are shown below, and Table 4 shows the evaluation results. (Evaluation Criteria) KM1024iMHE-D was used to perform 1-hour printing as the first ejection step, and after confirming that all 1024 nozzles had no ejection defects, a 6-hour pause step was set. Next, the above-mentioned KM1024iMHE-D was washed with a cleaning solution, the ink was refilled, and the second ejection step was performed for 2 hours. The cleaning performance was evaluated based on the number of nozzles with defective ejection in the second ejection step. A: No nozzle with bad ejection B: There are more than 0 and 5 or less nozzles with defective ejection C: There are more than 5 and 10 or less nozzles with poor ejection D: There are more than 10 bad nozzles

[Table 4] Liquid permeability washability Ink Composition 1 Ink Composition 2 Ink Composition 1 Ink Composition 2 Early stage 1 month later Early stage 1 month later Example 1 cleaning solution 1 A A B C B C Example 2 cleaning solution 2 A A B C B C Example 3 cleaning solution 3 A A B C B C Example 4 cleaning solution 4 - - A A - B Example 5 cleaning solution 5 - - A A - B Example 6 cleaning solution 6 - - A A - A Example 7 cleaning solution 7 - - A A - A Example 8 cleaning solution 8 B C C D C D Example 9 cleaning solution 9 A B C D C D Example 10 cleaning solution 10 - - B C - C Example 11 cleaning solution 11 - - B C - C Comparative Example 1 cleaning solution 12 - - D D D D Comparative Example 2 cleaning solution 13 - - D D D D

[Evaluation of Formability of QDCF] In the same manner as the above-mentioned evaluation of cleaning properties, with the combinations of ink compositions and cleaning solutions shown in Tables 5 and 6, after the ink compositions were ejected, the inkjet head was washed with the cleaning solution. net. Then, by inkjet printing using the ink composition shown in Table 5 or Table 6, the ink composition is filled in the bank on the glass substrate attached to the bank to form a precursor layer (made of ink with a thickness of 15 μm). layer of composition). Next, in a nitrogen atmosphere, the precursor layer was irradiated with UV to cure the precursor layer by a UV irradiation device using an LED lamp with a dominant wavelength of 395 nm so that the cumulative light amount was 10,000 mJ/cm ² , and the oxygen concentration was 1 volume. % or less was heated at 180°C for 30 minutes in a glove box to form a layer (light conversion layer) composed of a cured product of the ink composition, and a QDCF with a light conversion layer was obtained. The thickness change of the obtained light conversion layer was measured, and the QDCF formability was evaluated. The measurement method and evaluation criteria of the layer thickness are shown below, and the evaluation results are shown in Tables 5 and 6. (Measuring Method and Evaluation Criteria) The thickness of the light conversion layer was measured using a scanning white interference microscope manufactured by Hitachi High-Tech Science Co., Ltd., and evaluated by the coefficient of variation. In addition, the coefficient of variation is calculated based on the standard deviation/average value. A: Coefficient of variation is less than 3% B: Coefficient of variation is more than 3% and less than 4% C: Coefficient of variation is more than 4% and less than 5% D: Coefficient of variation is more than 5%

[Qy maintenance rate evaluation] In order to confirm the presence or absence of functional degradation (eg, deactivation) of the luminescent nanocrystals caused by the cleaning solution, the maintenance rate of Qy (absolute value of emission quantum yield) was evaluated by the following method. Qy was measured using Quantaurus-QY manufactured by Hamamatsu Photonics. Furthermore, Qy when the ink composition was diluted with the ink diluent was defined as Qy1, and Qy when the ink composition was diluted with each cleaning solution was defined as Qy2, and the Qy maintenance rate was calculated using the following formula. Qy maintenance rate = Qy2/Qy1 The evaluation criteria are shown below, and the evaluation results are shown in Tables 5 and 6. (Evaluation Criteria) A: The maintenance rate is more than 90% B: Maintenance rate is 70 or more and less than 90% C: Maintenance rate is more than 50 and less than 70% D: The maintenance rate is less than 50%

[table 5] ink composition cleaning solution QDCF formability Qy maintenance rate Example 1A 1 1 B A Example 2A 2 B A Example 3A 3 B A

[Table 6] ink composition cleaning solution QDCF formability Qy maintenance rate Example 1B 2 1 C A Example 2B 2 C A Example 3B 3 C A Example 4B 4 B A Example 5B 5 B A Example 6B 6 A A Example 7B 7 A A Example 8B 8 C A Example 9B 9 C D Example 10B 10 C A Example 11B 11 B D Comparative Example 1B 12 D D Comparative Example 2B 13 D D

10: Pixel part 10a: 1st pixel part 10b: 2nd pixel part 10c: 3rd pixel part 11a: The first luminescent nanocrystal 11b: Second luminescent nanoparticle 12a: The first light-scattering particle 12b: Second light-scattering particle 12c: Third light-scattering particle 20: Shading part 30: light conversion layer 40: Substrate 100: color filter

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

Claims (15)

A printing method, which is a method of printing an ink composition for forming a light conversion layer by using an inkjet method, the ink composition for forming a light conversion layer containing luminescent nanocrystal grains and a photopolymerizable compound, and the printing method Has the following steps: The step of cleaning the ink jet head after the above-mentioned ink composition is ejected by a cleaning liquid; and After the above-mentioned steps, the step of ejecting the above-mentioned ink composition from the above-mentioned inkjet head; and The above cleaning solution contains 80% by mass or more of low molecular weight compounds, The viscosity of the above cleaning solution at 25°C is less than 50 mPa·s, The vapor pressure of the above-mentioned low molecular compound at 25°C is below 650 Pa, The logP of the above-mentioned low molecular compound is -1-8. The printing method according to claim 1, wherein the content of the luminescent nanocrystals in the ink composition is 20% by mass or more based on the total mass of the ink composition. The printing method according to claim 1 or 2, wherein the surface tension of the cleaning solution at 25°C is 50 mN/m or less. The printing method according to any one of claims 1 to 3, wherein the dissolved oxygen concentration of the cleaning solution is 7 mass ppm or less. The printing method according to any one of claims 1 to 4, wherein the amount of water contained in the cleaning solution is 6000 mass ppm or less. The printing method according to any one of claims 1 to 5, wherein the vapor pressure of the low molecular compound at 25°C is 500 Pa or less. The printing method according to any one of claims 1 to 6, wherein the vapor pressure of the low molecular compound at 25°C is 400 Pa or less. The printing method according to any one of claims 1 to 7, wherein the logP of the low molecular weight compound is 1 to 5. The printing method according to any one of claims 1 to 8, wherein the PII value of the low molecular weight compound is less than 3. The printing method according to any one of claims 1 to 9, wherein the cleaning solution further contains a dispersant. The printing method according to any one of claims 1 to 10, wherein the cleaning solution does not substantially contain peroxide. The printing method according to any one of claims 1 to 11, wherein the cleaning solution further contains a surface conditioner. The printing method according to any one of claims 1 to 12, wherein the ink composition further contains light-scattering particles and a polymer dispersant. A method for forming a light conversion layer, which is a method for forming a light conversion layer of a cured product containing an ink composition, and has the following steps: The step of printing the above-mentioned ink composition by the printing method of any one of claims 1 to 13; and The step of hardening the above-mentioned ink composition by irradiating the obtained printed matter with light. A cleaning solution for cleaning an inkjet head after ejecting an ink composition for forming a light conversion layer containing luminescent nanocrystals and a photopolymerizable compound, The above cleaning solution contains 80% by mass or more of low molecular weight compounds, The viscosity at 25°C is less than 50 mPa·s, and The vapor pressure of the above-mentioned low molecular compound at 25°C is below 650 Pa, The logP of the above-mentioned low molecular compound is -1-8.

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