Dispersion liquid, curable composition, cured product of same, and electronic device

Abstract

The present invention provides: a dispersion liquid which contains a polymerizable monomer (a), a colorant (b), and a dispersant (c), wherein the colorant (b) contains at least a titania-based pigment, the content of the colorant (b) with respect to the entire dispersion liquid is within the range of 40 mass% to 80 mass%, and a solvent is not contained therein; and a curable composition. The dispersion liquid and the curable composition have excellent curability and storage stability, and are excellent in terms of heat resistance, light resistance, moisture resistance, light reflection characteristics, and adhesion to a substrate.

Description

Dispersion, curable composition, cured product thereof, and electronic device

[0001] The present invention relates to a dispersion, a curable composition, a cured product of the curable composition, an LED element including the cured product, and an electronic device using the cured product.

[0002] Display devices such as liquid crystal displays, plasma displays, organic electroluminescence (EL) displays, and mini-LED displays are widely used. In recent years, active development has been underway toward the practical application of micro-LED displays, which offer excellent properties such as brightness, color gamut, contrast, and reliability, and can achieve low power consumption by using high-luminous efficiency LEDs as light sources. Materials with excellent light reflectance have been developed with the aim of maintaining the characteristics of light-emitting elements, effectively utilizing light to increase brightness, and improving image quality and contrast. For example, Patent Document 1 discloses a white curable resin composition containing a specific titanium oxide and a curable resin. The cured product is said to be able to maintain high reflectance for a long period of time and be applicable to insulating layers (solder resist films) of printed wiring boards on which light-emitting elements such as LEDs are mounted, and reflectors for light-emitting elements such as electroluminescence or LEDs. Patent Document 2 discloses a resin composition preferably containing a specific polysiloxane resin, an organometallic compound containing a specific metal, a photopolymerization initiator or quinone diazide compound, a white pigment, and a solvent. The composition is said to be able to form a fine thick-film barrier rib pattern with high reflectance that separates color-converting phosphors, thereby improving the brightness of display devices. Patent Document 3 discloses a photosensitive composition for forming a bezel (light-shielding layer), which includes a white pigment, a binder resin that is a polymer having a carboxyl group or a polymer having a carboxyl group and a cyclic ether group, a polymerizable compound, and a specific photopolymerization initiator, and is said to have high whiteness, excellent chemical resistance, and light-shielding properties, and be suitable for producing display devices such as smartphones and tablet terminals. Patent Document 4 discloses an ultraviolet-curable white ink composition for inkjet printing, which includes a pigment dispersion, a binder solution that is an epoxy resin, a monofunctional monomer, and a specific photoinitiator, and which has a thickness and hiding power within a specified range during pattern formation. The composition is said to be able to form a white bezel pattern that does not yellow even after high-temperature heat treatment and has excellent adhesion, and to be applicable to liquid crystal display devices, displays, touch panels, etc.

[0003] JP 2011-017010 A, WO 2020 / 008969 A, JP 2016-027384 A, WO 2016 / 076662 A

[0004] The white curable resin composition disclosed in Patent Document 1 is adjusted to a viscosity suitable for the application method using an organic solvent, applied to a substrate by a method such as screen printing, and then photocured or thermally cured to obtain a cured coating film. When used as a reflector for light-emitting elements on a printed wiring board, the composition is processed to cut out a portion corresponding to the light-emitting element and then overlaid on the printed wiring board. In this case, adjusting the position of the processed coating film relative to the light-emitting element is difficult, especially when the area is large, and the cut-out hole must be made relatively larger than the light-emitting element. This makes it difficult to provide a reflective portion in close proximity to the light-emitting element, making it difficult to effectively reflect light from the light-emitting element upward (i.e., toward the display surface) of the printed wiring board, and also makes it difficult to effectively use light emitted from the side upward. The method of forming a pattern of partition walls on a base substrate using the resin composition disclosed in Patent Document 2 is preferably a photosensitive paste method, which includes a coating step in which the aforementioned resin composition is applied to a base substrate and dried to obtain a dried film, an exposure step in which the resulting dried film is exposed to light in a pattern according to the desired pattern shape, a development step in which portions of the exposed dried film that are soluble in a developer are dissolved and removed, and a heating step in which the developed partition walls are cured. The resulting partition wall-attached substrate is then placed opposite a separately prepared organic electroluminescent (EL) cell, for example, arranged on a glass substrate, and bonded together with a sealant to produce a display device. This makes the manufacturing process complicated and makes it difficult to adjust the position of the organic EL and the partition wall pattern.

[0005] The photosensitive composition for forming a bezel (light-shielding layer) disclosed in Patent Document 3 is typically prepared as a liquid composition by blending a solvent, and after coating the surface of a substrate, pre-baking is performed to evaporate the solvent to form a coating film. This coating film is then exposed to light through a photomask, the unexposed areas are removed with a developer, and post-baking is performed to form a white cured film to be used as the bezel, resulting in a complicated manufacturing process. The composition disclosed in Patent Document 4 contains an epoxy resin as an essential component, and merely forms a white bezel pattern that reflects only the light from the underside of the light-emitting element. Furthermore, the composition is inkjet-printed onto a substrate to a thickness of 30 μm or less to obtain a substrate with a white bezel formed. After irradiating the substrate with ultraviolet light to form a cured white bezel pattern, the substrate must then be further heat-treated (annealed).

[0006] In particular, for microLEDs, effectively utilizing light from the LED to irradiate the front surface is preferable in order to achieve high brightness and high contrast in light-emitting devices. Therefore, there is still room for improvement in existing materials such as those described in Patent Documents 1 to 4. Regarding compositions themselves as materials for constituting light-emitting elements to be applied to electronic devices using light-emitting elements such as LEDs, there is a need for compositions that can be applied by inkjet printing and do not require annealing treatment, from the perspectives of not only the production costs of the compounds to be blended, but also environmental considerations, responding to the trend toward thinner displays, and simplifying the production process and improving safety. After extensive research, the present inventors have found that dispersions containing specific colorants and polymerizable compounds as constituent components have low viscosity and excellent dispersibility and storage stability, that curable compositions prepared from such dispersions have low viscosity and excellent curability, can be formed into molded articles by inkjet printing, and the resulting cured articles have excellent physical properties such as heat resistance, light resistance, moisture resistance, and light reflectance properties, making them useful as materials for electronic devices having light-emitting elements such as LED elements. An object of the present invention is to provide a curable composition that can be used to form a cured product by an inkjet method, which has excellent curability and storage stability, as well as excellent heat resistance, light resistance, moisture resistance, light reflectance, and adhesion to a substrate.

[0007] The present invention has the following aspects. [1] A dispersion containing a polymerizable compound (a), a colorant (b), and a dispersant (c), wherein the colorant (b) contains at least a titania-based pigment, the content of the colorant (b) in the entire dispersion is in the range of 40 to 80 mass %, and the dispersion does not contain a solvent. [2] The dispersion of [1], wherein the polymerizable compound (a) contains a polymerizable compound having a viscosity of less than 9 mPa s at 25°C. [3] The dispersion of [1] or [2], wherein the polymerizable compound (a) contains a monofunctional (meth)acrylate (a1). [4] The dispersion of [3], wherein the monofunctional (meth)acrylate (a1) contains a monofunctional (meth)acrylate having an alicyclic skeleton. [5] The dispersion of any of [1] to [4], wherein the titania-based pigment in the colorant (b) has an average particle size (D50) of 200 to 500 nm. [6] A curable composition comprising the dispersion of any one of [1] to [5] and a photopolymerization initiator (d). [7] The curable composition of [6] further comprising a (meth)acrylate (a2) having a hydroxy group. [8] The curable composition of [6] or [7] further comprising a compound (a3) ​​having two or more (meth)acrylate groups. [9] The curable composition of any one of [6] to [8], wherein the photopolymerization initiator (d) comprises an oxime-based photopolymerization initiator.

[10] The curable composition of any one of [6] to [9], further comprising a silicone-based surfactant (e).

[11] The curable composition of any one of [6] to

[10] , wherein the viscosity at 25°C is 1 to 50 mPa·s.

[12] The curable composition of any one of [6] to

[11] , wherein the content of the colorant (b) is 30 to 70 mass% relative to the total mass of the curable composition.

[13] The curable composition of any one of [6] to

[12] , wherein the titania-based pigment in the colorant (b) has an average particle size (D50) of 200 to 500 nm.

[14] The curable composition of any one of [6] to

[13] , which is an active energy ray-curable composition.

[15] The curable composition of any one of [6] to

[14] , which does not contain a solvent.

[16] A cured product of the curable composition of any one of [6] to

[15] .

[17] The cured product of

[16] , wherein the reflectance of a film having a thickness of 4 μm or less, formed by coating and curing on a substrate, is 60% or more for light with a wavelength of 550 nm.

[18] A method for producing a cured product, comprising a step of curing the curable composition of any of [6] to

[15] by irradiating it with active energy rays.

[19] The production method of

[18] , wherein the curable composition is molded by an inkjet method.

[20] An electronic device using a cured product of the curable composition of any of [6] to

[15] .

[0008] According to the present invention, it is possible to provide a curable composition that can be formed by an inkjet method, which has low viscosity, excellent curability and storage stability, as well as excellent heat resistance, light resistance, moisture resistance, light reflectance, and adhesion to a substrate.

[0009] FIG. 1 is a diagram schematically illustrating an example of the configuration of a micro LED display, which is one embodiment of an electronic device using a cured product of the curable composition of the present invention as a partition wall.

[0010] The present invention relates to a dispersion containing a polymerizable compound (a), a colorant (b), and a dispersant (c), wherein the colorant (b) contains at least a titania-based pigment, the content of the colorant (b) relative to the total dispersion is in the range of 40 to 80 mass% and the dispersion does not contain a solvent (hereinafter simply referred to as the "dispersion of the present invention"). The present invention also relates to a curable composition containing the above-mentioned dispersion and a photopolymerization initiator (d) (hereinafter simply referred to as the "curable composition of the present invention"). Note that, in this specification, a composition containing the dispersion of the present invention, the photopolymerization initiator (d), and various components described below is referred to as a curable composition. In this specification, "(meth)acrylate" is a term that collectively refers to acrylate, methacrylate, and both. "(Meth)acrylic" is a term that collectively refers to acrylic, methacrylic, and both. The term "(meth)acryloyloxy group" is a general term that refers to an acryloyloxy group, a methacryloyloxy group, or both.

[0011] The dispersion of the present invention exhibits excellent dispersibility of the colorant (b) and excellent storage stability. The curable composition of the present invention contains the dispersion of the present invention as a constituent component and exhibits low viscosity and excellent curability and storage stability. Furthermore, the curable composition of the present invention can be used to form a cured product by inkjet printing that exhibits excellent heat resistance, light resistance, moisture resistance, light reflectivity, and adhesion to a substrate. That is, by using the curable composition of the present invention, partition walls can be formed in close proximity to light-emitting elements such as LEDs by inkjet printing, and this partition wall precursor can be cured to form white partition walls containing a titania-based pigment. Such partition walls can act as a reflector and reflect LED light without absorbing it or allowing it to escape to the sides of the light-emitting device, thereby effectively utilizing light in light-emitting electronic devices and increasing brightness, thereby contributing to improved image quality and contrast of light-emitting electronic devices. First, the composition of the dispersion of the present invention will be described.

[0012] The polymerizable compound (a) constituting the dispersion of the present invention preferably contains a polymerizable compound having a viscosity at 25°C of less than 20 mPa·s, more preferably less than 9 mPa·s, and even more preferably less than 7 mPa·s. The viscosity of such a polymerizable compound at 25°C is preferably 1 mPa·s or more, more preferably 2 mPa·s or more. When the polymerizable compound (a) contains a polymerizable compound having a viscosity at 25°C within the above range, the dispersion of the present invention tends to have excellent dispersibility, a low viscosity, and easy handling. Furthermore, the curable composition containing the dispersion of the present invention, which will be described later, becomes easy to handle and tends to have excellent ejection stability when an inkjet method is applied.

[0013] The polymerizable compound (a) preferably contains a monofunctional (meth)acrylate (a1). The inclusion of the monofunctional (meth)acrylate (a1) makes it easier to reduce the viscosity of the dispersion of the present invention and the curable composition of the present invention containing the dispersion of the present invention, which will be described later. The monofunctional (meth)acrylate (a1) is preferably a (meth)acrylate having a cyclic skeleton, and examples thereof include a monofunctional (meth)acrylate having an aromatic ring, a (meth)acrylate having a cyclic skeleton containing a heteroatom, and a (meth)acrylate having an alicyclic skeleton.

[0014] Examples of monofunctional (meth)acrylates having an aromatic ring include 2-phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, m-phenoxybenzyl (meth)acrylate, 1-naphthalenemethyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, and phenoxy(polyethylene glycol) (meth)acrylate. Examples of (meth)acrylates having a cyclic skeleton containing a heteroatom include (meth)acryloylmorpholine, N-(meth)acryloyloxyethylhexahydrophthalimide, tetrahydrofurfuryl (meth)acrylate, and cyclic trimethylolpropane formal (meth)acrylate. Commercially available (meth)acrylates having a cyclic skeleton containing a heteroatom can also be used, such as those available under the product names "Viscoat 150" and "Viscoat 200" manufactured by Osaka Organic Chemical Industry Ltd.

[0015] Examples of the (meth)acrylate having an alicyclic skeleton include monofunctional (meth)acrylates having a cyclic aliphatic group, such as cyclohexyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, tricyclodecane dimethanol mono(meth)acrylate, adamantyl (meth)acrylate, cyclohexane dimethanol mono(meth)acrylate, trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate.

[0016] These monofunctional (meth)acrylates (a1) may be used alone or in combination of two or more. Among them, monofunctional (meth)acrylates (a1) having a viscosity of less than 9 mPa s at 25°C are more preferred, and examples thereof include trimethylcyclohexyl acrylate as a (meth)acrylate having an alicyclic skeleton and benzyl acrylate as a monofunctional (meth)acrylate having an aromatic ring. When the dispersion of the present invention contains, as the polymerizable compound (a), a monofunctional (meth)acrylate (a1) having a viscosity of less than 9 mPa s at 25°C, the handleability of the dispersion is improved and the dispersibility of the titania-based pigment contained in the colorant (b) is more likely to be improved. In other words, the polymerizable compound (a) is preferably composed of a monofunctional (meth)acrylate (a1) within a range in which the viscosity of the dispersion of the present invention and the dispersibility of the colorant (b) can be maintained, more preferably composed of a monofunctional (meth)acrylate (a1) having a viscosity of less than 9 mPa s at 25°C, and even more preferably composed of a monofunctional (meth)acrylate having an alicyclic skeleton and having a viscosity of less than 9 mPa s at 25°C.

[0017] The content of the polymerizable compound (a) in the dispersion of the present invention is preferably in the range of 20 to 60% by mass, more preferably in the range of 25 to 55% by mass, and even more preferably in the range of 30 to 50% by mass. Note that, in addition to the monofunctional (meth)acrylate (a1), the polymerizable compound (a) may further contain one or more of a (meth)acrylate (a2) having a hydroxy group or a compound (a3) ​​having two or more (meth)acrylate groups, which are preferably contained in the curable composition of the present invention described below, within a range that does not increase the viscosity of the dispersion of the present invention and can maintain the dispersibility of the colorant (b).

[0018] The colorant (b) constituting the dispersion of the present invention contains at least a titania-based pigment. Examples of titania-based pigments include white pigments such as titanium oxide and strontium titanate. Titanium oxide is particularly preferred. The crystal form of titanium oxide is classified into anatase, rutile, and brookite. Among these, rutile is preferred. Rutile-type titanium oxide can be obtained by known methods such as the chlorine method and sulfuric acid method. Titanium-based pigments such as chlorine-process titanium oxide (rutile type) and sulfuric acid-process titanium oxide (rutile type) may have their surfaces treated with other metals such as alumina or siloxane, and preferably have a titanium oxide content of 90% by mass or more. One type of titania-based pigment may be used alone, or two or more types may be used in combination. From the viewpoint of further improving the whiteness and light reflectance of the cured product of the curable composition of the present invention, which will be described later, it is more preferred to use chlorine-process titanium oxide as the titania-based pigment. Such titania pigments can be commercially available products, such as the titanium oxide WHITE product "CR" series manufactured by Ishihara Sangyo Kaisha, Ltd., and the "Tipure (registered trademark) R" series manufactured by Chemours.

[0019] The content of the colorant (b) containing at least a titania-based pigment relative to the total dispersion of the present invention is in the range of 40 to 80% by mass, preferably in the range of 55 to 75% by mass, and more preferably in the range of 60 to 75% by mass. The content of the colorant (b) within the above-mentioned range is preferred from the viewpoint of maintaining the viscosity of the dispersion, which varies depending on the blending ratio of the polymerizable compound (a), the colorant (b), and the dispersant (c), within a favorable range for ease of handling. Furthermore, the curability of the curable composition of the present invention, which will be described later and which contains the dispersion of the present invention, and the light resistance and light reflectance properties of the cured product of the curable composition of the present invention can be improved.

[0020] The average particle diameter (D50) of the titania-based pigment in colorant (b) is preferably 200 to 500 nm, more preferably 200 to 400 nm, and even more preferably 220 to 350 nm. When the average particle diameter (D50) of the titania-based pigment is 350 nm or less, the curable composition of the present invention (described below) containing the dispersion of the present invention becomes easier to handle, exhibits excellent ejection stability when used in an inkjet method, and is less susceptible to nozzle clogging. Furthermore, when the average particle diameter (D50) is 220 nm or more, the light transmittance of the cured product of the curable composition of the present invention can be sufficiently reduced, thereby improving the light reflection properties. The average particle diameter (D50) is the cumulative 50% diameter on a volume basis, and is determined by laser diffraction / scattering.

[0021] The dispersion of the present invention may further contain other colorants in addition to the titania-based pigment as the colorant (b) to the extent that the effects of the present invention are not impaired.

[0022] The dispersant (c) is used in the dispersion of the present invention for the purpose of further improving the dispersion stability of the colorant (b) in the polymerizable compound (a1). As the dispersant (c), a polymer dispersant having both a pigment-affinity group that chemically bonds to or adsorbs to the pigment surface and a polymer chain or group that is solvent-philic is preferred. The polymer dispersant improves the pigment's wettability to the dispersion medium, promoting deagglomeration of the pigment, stabilizing the pigment particle size and viscosity through its steric hindrance and electrostatic repulsion effects, and further improving the viscosity reduction and storage stability of the dispersion of the present invention or the curable composition of the present invention described below. Examples of polymer dispersants include polyester-based, acrylic-based, polyurethane-based, polyallylamine-based, carbodiimide-based, and polyamide-based dispersants. Commercially available products can be used as the dispersant (c), for example, Ajinomoto Fine-Techno Co., Ltd.'s Ajisper (Ajisper is a registered trademark) PB821, PB822, PB824; Lubrizol's Solsperse (Solsperse is a registered trademark) 24000GR, 32000, 33000, 36000, 39000, 41000; Kusumoto Chemical Co., Ltd.'s Disparlon DA-703-50; BASF's EFKA (EFKA is a registered trademark) PX4701, PX4703; EVONIK's, Dispers TEGO (registered trademark) 685, Dispers TEGO (registered trademark) 655; Kawaken Fine Chemicals Co., Ltd.'s Hinoact T-6000, and the like. The amount of dispersant (c) used is preferably in the range of 1 to 20% by mass relative to the colorant (b), and more preferably in the range of 2 to 10% by mass from the viewpoint of achieving better inkjet ejection stability and dispersion stability of colorant (b) in the curable composition of the present invention, which will be described later. If the amount of dispersant (c) used is less than 1% by mass, sedimentation or aggregation of colorant (b) occurs, and the stability of the dispersion tends to decrease. On the other hand, if it is more than 20% by mass, the viscosity of the dispersion increases, and the inkjet ejection stability of the curable composition of the present invention may deteriorate.

[0023] The dispersion of the present invention may further contain a surfactant from the viewpoints of improving handleability, dispersibility of the colorant (b), and the discharge stability and substrate wettability of the curable composition of the present invention, which will be described later. When the dispersion of the present invention contains a surfactant, the amount thereof is preferably 0.05 to 1 mass %, and more preferably 0.07 to 0.8 mass %, based on the total mass of the dispersion of the present invention. The surfactant will be described in detail in the description of the curable composition of the present invention.

[0024] The dispersion of the present invention is characterized by not containing a solvent. In this specification, the term "solvent" refers to a compound that dissolves the polymerizable compound (a), the dispersant (c), and the photopolymerization initiator (d) but does not react with these components. Examples of such solvents include ethers such as 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, anisole, and phenetole; esters such as methyl lactate, ethyl lactate, butyl lactate, methyl 2-hydroxyisobutanoate, ethyl acetate, butyl acetate, pentyl formate, isopentyl acetate, butyl propionate, isopropyl butyrate, ethyl butyrate, butyl butyrate, methyl pyruvate, methyl acetoacetate, and γ-butyrolactone; ether esters such as ethyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, 3-methoxybutyl acetate, and 3-methyl-3-methoxybutyl acetate; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dipropyl ether, and diethylene glycol dibutyl ether;Examples of suitable solvents include glycol ether esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, and dipropylene glycol methyl ether acetate; alcohols such as methanol, ethanol, propanol, butanol, hexanol, cyclohexanol, ethylene glycol, and propylene glycol; ketones such as acetone, 2-butanone, 2-heptanone, 4-methyl-2-pentanone, cyclopentanone, and cyclohexanone; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; aliphatic hydrocarbons such as hexane and octane; and aromatic hydrocarbons such as benzene, toluene, and xylene. Furthermore, the phrase "solvent-free" used herein means that the solvent content in the dispersion of the present invention is 1% by mass or less. The content of the solvent is preferably 0.5% by mass or less, more preferably 0.1% by mass or less. The dispersion of the present invention can well disperse the colorant (b) containing at least a titania-based pigment, even without containing a solvent, and has excellent storage stability. Therefore, the production process of the dispersion of the present invention can be simplified, and handling safety can be improved. Furthermore, the curable composition of the present invention described below can be applied by an inkjet method, and a solvent drying step or annealing treatment is not required when curing.

[0025] The dispersion of the present invention can be produced by using a conventional dispersing machine such as a bead mill or a stirrer to supply the polymerizable compound (a), colorant (b), and dispersant (c) and stir and mix them to disperse the colorant (b). When a bead mill is used, glass beads or zirconia beads can be used as the beads. Here, as the dispersing machine, various known and commonly used dispersing machines can be used, such as a bead mill, an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a Dyno Mill, a Dispermat, an SC Mill, a Nanomizer, etc.

[0026] Next, the configuration of the curable composition of the present invention will be described. The curable composition of the present invention may be a curable composition that is cured by heat or a curable composition that is cured by active energy rays. From the viewpoint of more suitable use as a partition wall forming material for micro LEDs, which will be described later, the curable composition of the present invention is preferably a curable composition that is cured by active energy rays. For this reason, the curable composition of the present invention contains the dispersion liquid of the present invention described above and a photopolymerization initiator (d).

[0027] Examples of the photopolymerization initiator (d) include 2-methylbenzoyldiphenylphosphine oxide, bis(2,6-dichlorobenzoyl)phenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, 2,6-dimethoxybenzoyldiphenylphosphine oxide, 2,6-dichlorobenzoyldiphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-di Acylphosphine compounds such as methylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,5-dimethylphenylphosphine oxide; phosphinic acid ester compounds such as methyl (2,4,6-trimethylbenzoyl)phenylphosphinate, ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate, methyl (3-benzoyl-2,4,6-trimethylbenzoyl)phenylphosphinate, ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)phenylphosphinate, and isopropyl pivaloylphenylphosphinate; ketocoumarin compounds such as 3-ketocoumarin derivatives;Benzoin isobutyl ether, 2,4-diethylthioxanthone [also known as 2,4-diethylthioxanthen-9-one], 2-isopropylthioxanthone, methyl benzoyl formate, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 1-hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzil dimethyl ketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methyl propan-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, benzophenone, 4-phenylbenzophenone, isophthalphenone, 4-benzoyl-4'-methyldiphenyl sulfide, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholinophenyl)-butan-1-one), 1-{4-[(4-benzoylphenyl)sulfanyl]phenyl}-2-methyl-2-[(4-methylphenyl)sulfonyl]propan-1-one, and the like.

[0028] Among these, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, ethyl (2,4,6-trimethylbenzoyl)phenylphosphinate, and ethyl (3-benzoyl-2,4,6-trimethylbenzoyl)phenylphosphineate are preferred, as they correspond to the wavelength of light emitted from an ultraviolet light-emitting diode (UV-LED) light source as a light source of active energy rays. In particular, when a UV-LED having a main peak wavelength of 365 to 405 nm is used as the light source, it is preferred to use an acylphosphine compound, in particular phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide or (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, as the photopolymerization initiator.

[0029] Furthermore, it is preferable that the photopolymerization initiator (d) contains an oxime-based photopolymerization initiator. When the curable composition of the present invention contains an oxime-based photopolymerization initiator as the photopolymerization initiator (d), it is easy to uniformly cure even when applied thickly, and has excellent curability, and the obtained cured product tends to have excellent heat resistance, moisture resistance, and adhesion. Examples of oxime-based photopolymerization initiators include those described in J. C. S. Perkin II, 1979, pp. 1653-1660, J. C. S. Perkin II, 1979, pp. 156-162, and J. Photopolym. Sci. Tech., 1995 ...653-1660, J. C. S. Perkin II, 1979, pp. 1653-1660, and J. Photopolym. Sci. Tech., 1995, pp. 1653-1660, J. C. S. Perkin II, 1979, pp. 1653-1660, and J. Photopolym Examples of the oxime compound include compounds described in JP-A-202-232, JP-A-2000-66385, JP-A-2000-80068, JP-A-2001-233842, JP-T-2004-534797, JP-A-2006-342166, JP-A-2007-269779, JP-A-2009-191061, and JP-A-2012-032556. Among these, the oxime compound is preferably an oxime-based photopolymerization initiator having a maximum absorption wavelength in the wavelength region of 350 nm to 500 nm, and more preferably an oxime-based photopolymerization initiator having an absorption wavelength in the wavelength region of 360 nm to 480 nm. Commercially available oxime-based photopolymerization initiators can be used, and examples thereof include "Irgacure OXE01," "Irgacure OXE02," "Irgacure OXE03," and "Irgacure OXE04" manufactured by BASF Japan Ltd., and "TR-PBG-304" manufactured by Changzhou Strong Electronic New Materials Co., Ltd.

[0030] In addition, it is more preferable to use a hydrogen abstraction photopolymerization initiator in combination in order to obtain good surface curability and high reflectance. For example, Omnirad DETX manufactured by IGM can be mentioned. The amount of these hydrogen abstraction photopolymerization initiators added is preferably 0.1 to 10 mass %, more preferably 0.3 to 8 mass %, and even more preferably 0.5 to 5 mass %, based on the total amount of the curable composition of the present invention.

[0031] The photopolymerization initiator (d) may be contained alone or in combination of two or more. The content of the photopolymerization initiator (d) in the curable composition of the present invention is preferably 0.1 to 15 mass%, more preferably 1.0 to 12 mass%, and even more preferably 2.0 to 10 mass%, based on the total mass of the curable composition of the present invention. When the content of the photopolymerization initiator (d) is within the above range, the curability and storage stability of the curable composition of the present invention become good, and the performance of the formed cured product tends to be improved.

[0032] The curable composition of the present invention may further contain a sensitizer. Examples of sensitizers include trimethylamine, methyldimethanolamine, triethanolamine, p-diethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N,N-dimethylbenzylamine, 4,4'-bis(diethylamino)benzophenone, diethoxyanthracene, dibutoxyanthracene, anthracene-9,10-diethyl ether, and 9,10-bis(n-heptanoyloxy)anthracene. Examples include UVS-581, UVS-2171, and UVS-1331 manufactured by Air Water Inc. When the curable composition of the present invention contains a sensitizer, the content thereof is preferably 0.1 to 15% by mass, and more preferably 0.5 to 8% by mass, based on the total mass of the curable composition of the present invention. When the content of the sensitizer is within the above range, the curable composition of the present invention has good curability, and the performance of the cured product formed tends to be improved.

[0033] In addition to the above-described components, the curable composition of the present invention may further contain, if necessary, a polymerization inhibitor such as hydroquinone, di-t-butylhydroquinone, p-methoxyphenol, benzoquinone, dibutylhydroxytoluene, nitrosamine salts, hindered amine compounds, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), etc. When a polymerization inhibitor is contained, the amount thereof is preferably in the range of 0.01 to 2 mass % relative to the total amount of the curable composition of the present invention.

[0034] Furthermore, the curable composition of the present invention preferably further contains a (meth)acrylate (a2) having a hydroxy group. Examples of the (meth)acrylate (a2) having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-ethylhexyl diglycol (meth)acrylate, diethylene glycol mono(meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 1,4-cyclohexanedimethanol monoacrylate, and 1-(acryloyloxy)-3-(methacryloyloxy)-2-propanol. These (meth)acrylates (a2) having a hydroxy group may be used alone or in combination of two or more. Among these, 2-hydroxypropyl(meth)acrylate and 4-hydroxybutyl(meth)acrylate are preferred, and 4-hydroxybutyl(meth)acrylate is more preferred, from the viewpoints of being versatile, relatively inexpensive, and providing good curability, inkjet ejection properties, and excellent physical properties such as moisture resistance and heat resistance of the cured product after curing. When the polymerizable compound (a2) contains a (meth)acrylate having a hydroxy group, the moisture resistance, heat resistance, and adhesion to a substrate of the cured product formed from the curable composition of the present invention are improved.

[0035] The content of the (meth)acrylate (a2) having a hydroxy group is preferably in the range of 1 to 50 mass %, more preferably in the range of 3 to 40 mass %, and even more preferably in the range of 4 to 35 mass %, relative to the total mass of the curable composition of the present invention. When the curable composition of the present invention contains the (meth)acrylate having a hydroxy group in such a range, the curability is improved, and the performance of the cured product after curing, such as moisture resistance, heat resistance, and adhesion to a substrate, is improved.

[0036] The curable composition of the present invention preferably further contains a compound (a3) ​​having two or more (meth)acrylate groups. Examples of the compound (a3) ​​having two or more (meth)acrylate groups include ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 2-methyl-1,8-octanediol di(meth)acrylate, and 2-butyl-2-ethyl-1,3-propanediol di(meth). glycol di(meth)acrylates such as hydroxypivalic acid neopentyl glycol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethoxylated (2) neopentyl glycol di(meth)acrylate [a compound obtained by di(meth)acrylating a neopentyl glycol ethylene oxide 2-mol adduct], propoxylated (2) neopentyl glycol di(meth)acrylate [a compound obtained by di(meth)acrylating a neopentyl glycol propylene oxide 2-mol adduct], and hydroxypivalic acid neopentyl glycol di(meth)acrylate;

[0037] Alkylene glycol di(meth)acrylates such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and bis(4-acryloxypolyethoxyphenyl)propane; di(meth)acrylate of tris(2-hydroxyethyl)isocyanurate; dimethyloltricyclodecane di(meth)acrylate, and caprolactone-modified hydroxypivalic acid neopentyl glycol di(meth)acrylate; trifunctional (meth)acrylates such as bisphenol A di(meth)acrylate, propylene oxide-modified bisphenol A di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, propylene oxide-modified bisphenol F di(meth)acrylate, and ethylene oxide-modified bisphenol F di(meth)acrylate; trifunctional (meth)acrylates such as pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethylene oxide-modified tri(meth)acrylate, trimethylolpropane propylene oxide-modified tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, modified glycerin tri(meth)acrylate, propylene oxide adduct tri(meth)acrylate of glycerin, and ethylene oxide adduct tri(meth)acrylate of glycerin; tetrafunctional (meth)acrylates such as pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and tetramethylolmethane tetra(meth)acrylate; hexafunctional (meth)acrylates such as dipentaerythritol hexa(meth)acrylate and caprolactone-modified dipentaerythritol hexa(meth)acrylate; and the like.

[0038] Furthermore, urethane (meth)acrylate and amino (meth)acrylate can also be used as the compound (a3) ​​having two or more (meth)acrylate groups. The urethane (meth)acrylate and amino (meth)acrylate may be any of a monomer, oligomer, and polymer. In this specification, "monomer" refers to a compound having a molecular weight (weight average molecular weight if the molecular weight is distributed) of 1,000 or less. The molecular weight of the monomer (weight average molecular weight if the molecular weight is distributed) is 50 to 1,000. "Oligomer" generally refers to a polymer having a finite number of monomer-based structural units (generally 5 to 100) and a weight average molecular weight greater than 1,000 and less than 30,000. "Polymer" refers to a polymer having a weight average molecular weight of 30,000 or more. The weight average molecular weight is measured by gel permeation chromatography (GPC) and calculated as a standard polystyrene equivalent value.

[0039] Examples of the urethane (meth)acrylate include aliphatic urethane (meth)acrylate and aromatic urethane (meth)acrylate. The weight average molecular weight of the urethane (meth)acrylate is preferably 1,000 to 30,000, more preferably 2,000 to 20,000. Commercially available urethane (meth)acrylates can also be used, such as U-2PPA, U-4HA, U-6HA, U-6LPA, U-15HA, U-324A, UA-122P, UA5201, and UA-512 manufactured by Shin-Nakamura Chemical Co., Ltd.; CN965NS, CN964A85, CN964, CN959, CN962, CN963J85, CN965, and CN982B88 manufactured by ARKEMA (Sartomer); CN981, CN983, CN991, CN996, CN9002, CN9906NS, CN9007, CN9009, CN9010, CN9011, CN9178, CN9788, CN9893; and EBECRYL230, EBECRYL270, EBECRYL8402, EBECRYL8804, EBECRYL8807, EBECRYL9270, KRM8191 manufactured by Daicel-Allnex Co., Ltd.

[0040] The amino(meth)acrylate is an amine-modified (meth)acrylate having an amino group. The number average molecular weight of the amino(meth)acrylate is preferably 500 to 20,000, more preferably 600 to 10,000, and even more preferably 800 to 5,000. Commercially available amino(meth)acrylates can also be used, such as EBECRYL7100 and EBECRYL80 manufactured by Daicel-Allnex Corporation and CN551 manufactured by ARKEMA (manufactured by Sartomer).

[0041] The compound (a3) ​​having two or more (meth)acrylate groups may be used alone or in combination of two or more. The content of the compound (a3) ​​having two or more (meth)acrylate groups in the curable composition of the present invention is preferably in the range of 1 to 20 mass%, more preferably in the range of 2 to 15 mass%, and even more preferably in the range of 3 to 12 mass%, relative to the total mass of the curable composition of the present invention. When the curable composition of the present invention contains the compound (a3) ​​having two or more (meth)acrylate groups in such a range, the curability of the curable composition of the present invention is improved, and further, the performance of the cured product formed from the curable composition of the present invention, such as flexibility and adhesion to a substrate, is improved. Furthermore, when one type of compound is used alone as the compound (a3) ​​having two or more (meth)acrylate groups, for example, when a compound having three or more (meth)acrylate groups such as the above-exemplified trifunctional (meth)acrylates or tetrafunctional (meth)acrylates, such as trimethylolpropane ethylene oxide-modified triacrylate, is used, the hardness of the cured product formed from the curable composition of the present invention can be increased, and the heat resistance and moisture resistance can also be effectively improved.

[0042] The curable composition of the present invention may further contain a (meth)acrylate having a phosphate group and a (meth)acrylate having a cyclic skeleton, in addition to the (meth)acrylate (a2) having a hydroxy group and the compound (a3) ​​having two or more (meth)acrylate groups described above.

[0043] Examples of the (meth)acrylate having a phosphate group include alkylene (meth)acrylate phosphates such as methylene (meth)acrylate phosphate, ethylene (meth)acrylate phosphate, propylene (meth)acrylate phosphate, and tetramethylene (meth)acrylate phosphate; phosphate esters of polyethylene glycol monoacrylate; and phosphate esters of polypropylene glycol monomethacrylate.

[0044] Commercially available (meth)acrylates having a phosphate group can also be used, and examples thereof include those manufactured by Daicel-Allnex Co., Ltd. under the product name "EBECRYL168," and those manufactured by Nippon Kayaku Co., Ltd. under the product names "KAYAMER PM-2" and "KAYAMER PM-21," manufactured by Unichemical Co., Ltd. under the product names "Phosmer M," "Phosmer PE," and "Phosmer PP," manufactured by Kyoeisha Chemical Co., Ltd. under the product names "Light Ester P-1M," "Light Acrylate P-1A(N)," and "Light Ester P-2M," manufactured by Kyoeisha Chemical Co., Ltd., and "JPA-514" manufactured by Johoku Chemical Industry Co., Ltd.

[0045] The (meth)acrylate having a phosphate group may be used alone or in combination of two or more. When the curable composition of the present invention contains a (meth)acrylate having a phosphate group, the amount thereof is preferably in the range of 0.1 to 10 mass %, more preferably in the range of 0.2 to 8 mass %, relative to the total mass of the curable composition of the present invention. When the curable composition of the present invention contains a (meth)acrylate having a phosphate group in such a range, the curability of the curable composition of the present invention is improved, and further, the performance of the cured product formed from the curable composition of the present invention, such as adhesion to a substrate, is improved.

[0046] Examples of the (meth)acrylate having a cyclic skeleton include the monofunctional (meth)acrylate having an aromatic ring, the (meth)acrylate having a cyclic skeleton containing a heteroatom, and the (meth)acrylate having an alicyclic skeleton, as described above in the monofunctional (meth)acrylate (a1). The (meth)acrylate having a cyclic skeleton may be used alone or in combination of two or more. When the (meth)acrylate having a cyclic skeleton is contained, it becomes easy to adjust the viscosity of the curable composition of the present invention to a suitable viscosity range when molding by an inkjet method. In addition, the shrinkage of the cured product formed from the curable composition of the present invention is reduced, and the cured product has excellent adhesion, etc.

[0047] In this specification, (meth)acrylates having a hydroxyl group and a cyclic skeleton are classified as (meth)acrylates (a2) having a hydroxyl group, and (meth)acrylates having a phosphate group and a cyclic skeleton are classified as (meth)acrylates having a phosphate group. Furthermore, monomers having two or more (meth)acrylate groups, regardless of whether they have a cyclic skeleton, are classified as (meth)acrylates (a2) having a hydroxyl group or (meth)acrylates having a phosphate group if they have at least one hydroxyl group or phosphate group, and are classified as compounds (a3) ​​having two or more (meth)acrylate groups if they have neither a hydroxyl group nor a phosphate group. In other words, (meth)acrylates having a cyclic skeleton include mono(meth)acrylates having a cyclic skeleton and neither a hydroxyl group nor a phosphate group.

[0048] When the curable composition of the present invention contains a (meth)acrylate having a cyclic skeleton, the amount is preferably within 50% by mass, more preferably within 45% by mass, and even more preferably within 40% by mass, relative to the total mass of the curable composition of the present invention. When the curable composition of the present invention contains a (meth)acrylate having a cyclic skeleton in an amount of 50% by mass or less, the curability of the curable composition of the present invention is improved, its storage stability and shrinkage of the formed cured product are suppressed, and performance such as adhesion to the substrate is improved. Here, when a (meth)acrylate having a cyclic skeleton is blended into the curable composition of the present invention, the (meth)acrylate having a cyclic skeleton may contain the same type of compound as the compound described above in the monofunctional (meth)acrylate (a1). In this case, the content of the (meth)acrylate having a cyclic skeleton relative to the entire curable composition of the present invention may be calculated from the total amount of the monofunctional (meth)acrylate having a cyclic skeleton in the monofunctional (meth)acrylate (a1) derived from the dispersion of the present invention and the (meth)acrylate having a cyclic skeleton blended in the curable composition.

[0049] The (meth)acrylate (a2) having a hydroxy group, the compound (a3) ​​having two or more (meth)acrylate groups, the (meth)acrylate having a phosphate group, and the (meth)acrylate having a cyclic skeleton may be compounds made from biomass raw materials. In such cases, the curable composition of the present invention itself can be considered an environmentally friendly product, which is more preferable from the viewpoint of reducing the environmental load.

[0050] The curable composition of the present invention may further contain another polymerizable compound different from the above-mentioned polymerizable compound (a). Examples of the other polymerizable compound include a monofunctional polymerizable compound different from the above-mentioned monofunctional (meth)acrylate (a1), or a polymerizable compound having two or more polymerizable groups (hereinafter referred to as a "polyfunctional polymerizable compound") different from the above-mentioned compound (a3) ​​having two or more (meth)acrylate groups. Here, the polymerizable group refers to a group having a polymerizable unsaturated double bond.

[0051] The monofunctional polymerizable compound is preferably a compound that has a polymerizable unsaturated double bond and is liquid at 25°C, and its molecular weight is preferably 60 to 2000, more preferably 100 to 1000. The viscosity of such a monofunctional polymerizable compound is preferably 1000 mPa·s or less, more preferably 300 mPa·s or less. The viscosity is preferably 1 mPa·s or more, more preferably 3 mPa·s or more.

[0052] Examples of the monofunctional polymerizable compound that is another polymerizable compound include a polymerizable compound having a heterocyclic structure and a monovinyl ether compound. Examples of the polymerizable compound having a heterocyclic structure include N-vinylcaprolactam, N-vinylpyrrolidone, and N-vinylformamide.

[0053] Examples of the monovinyl ether compound include ethylene glycol monovinyl ether, triethylene glycol monovinyl ether, hydroxyethyl monovinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, hydroxynonyl monovinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, phenyl glycidyl ether, butyl glycidyl ether, and 2-ethylhexyl glycidyl ether.

[0054] Examples of the polyfunctional polymerizable compound that is another polymerizable compound include a compound represented by the following general formula (1): ２ =CR ４ -COO-R ５ -O-CH=CH-R ６ ...(1) (wherein, R ４ represents a hydrogen atom or a methyl group, R ５ represents an organic residue having 2 to 20 carbon atoms, and R ６represents a hydrogen atom or an organic residue having 1 to 11 carbon atoms.) (hereinafter simply referred to as "monomer (1)"), divinyl ether compounds, trivinyl ether compounds, etc. ５ Examples of the organic residue having 2 to 20 carbon atoms represented by R include a linear, branched or cyclic alkylene group having 2 to 20 carbon atoms, an alkylene group having 2 to 20 carbon atoms having an oxygen atom in its structure via an ether bond and / or an ester bond, and an aromatic group having 6 to 11 carbon atoms in which a hydrogen atom bonded to a carbon atom constituting the ring may be substituted with another substituent, and an alkylene group having 2 to 6 carbon atoms and an alkylene group having 2 to 9 carbon atoms having an oxygen atom in its structure via an ether bond are preferred. ６ Examples of the organic residue having 1 to 11 carbon atoms represented by the formula (I) include a linear, branched, or cyclic alkyl group having 1 to 10 carbon atoms, and an aromatic group having 6 to 11 carbon atoms in which a hydrogen atom bonded to a carbon atom constituting the ring may be substituted with another substituent, and an alkyl group having 1 or 2 carbon atoms and an aromatic group having 6 to 8 carbon atoms are preferred.

[0055] Specific examples of the monomer (1) include 2-vinyloxyethyl (meth)acrylate, 3-vinyloxypropyl (meth)acrylate, 1-methyl-2-vinyloxyethyl (meth)acrylate, 2-vinyloxypropyl (meth)acrylate, 4-vinyloxybutyl (meth)acrylate, 1-methyl-3-vinyloxypropyl (meth)acrylate, 1-vinyloxymethylpropyl (meth)acrylate, 2-methyl-3-vinyloxypropyl (meth)acrylate, and 3-methyl-3-vinyloxypropyl (meth)acrylate. vinyloxypropyl, 1,1-dimethyl-2-vinyloxyethyl (meth)acrylate, 3-vinyloxybutyl (meth)acrylate, 1-methyl-2-vinyloxypropyl (meth)acrylate, 2-vinyloxybutyl (meth)acrylate, 4-vinyloxycyclohexyl (meth)acrylate, 5-vinyloxypentyl (meth)acrylate, 6-vinyloxyhexyl (meth)acrylate, 4-vinyloxymethylcyclohexylmethyl (meth)acrylate, p-vinyloxymethylphenyl (meth)acrylate Methyl, 2-(vinyloxyethoxy)ethyl (meth)acrylate, 2-(vinyloxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxy)propyl (meth)acrylate, 2-(vinyloxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)ethyl (meth)acrylate, 2-(vinyloxy) Examples of the monomer (1) include 2-(vinyloxyethoxyisopropoxy)ethyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)propyl (meth)acrylate, 2-(vinyloxyethoxyethoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyisopropoxy)isopropyl (meth)acrylate, 2-(vinyloxyethoxyethoxyethoxy)ethyl (meth)acrylate, polyethylene glycol monovinyl ether (meth)acrylate, and polypropylene glycol monovinyl ether (meth)acrylate. From the viewpoints of low viscosity, high flash point, and excellent curability, 2-(2-vinyloxyethoxy)ethyl (meth)acrylate is preferred, and 2-(2-vinyloxyethoxy)ethyl acrylate is more preferred.

[0056] Examples of divinyl ether compounds or trivinyl ether compounds include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylolpropane trivinyl ether.

[0057] When the curable composition of the present invention further contains another polymerizable compound, the other polymerizable compound may be used alone or in combination of two or more. When the other polymerizable compound is further contained, the content is preferably 30 mass % or less, more preferably 20 mass % or less, based on the total curable composition of the present invention, and from the viewpoint of easily adjusting the viscosity of the obtained curable composition of the present invention and the cure shrinkage rate of the cured product of the curable composition of the present invention, still more preferably 10 mass % or less.

[0058] The curable composition of the present invention may further contain a surfactant from the viewpoint of ensuring handling properties and ejection stability applicable to inkjet method, and adjusting surface tension to a desired range.Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, etc.; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene-polyoxypropylene block copolymers, etc.; cationic surfactants such as alkylamine salts, quaternary ammonium salts, etc.; compounds having a silicone chain, silicone surfactants having a polymer chain such as a silicone chain and a poly(meth)acrylate chain, silicone surfactants having a polyether chain at the side chain or end and a polysiloxane structure in the main chain; fluorine surfactants having a perfluoroalkyl chain, oily fluorine compounds (e.g., fluorine oil) and solid fluorine compound resins (e.g., tetrafluoroethylene resin), etc., preferably hydrophobic organic fluorocompounds. These are available as commercially available products, such as the "Megafac (registered trademark)" series manufactured by DIC Corporation, the "Ftergent (registered trademark)" series manufactured by Neos Corporation, the "BYK (registered trademark)" series manufactured by BYK Corporation, the "TEGO (registered trademark) Rad" series manufactured by Evonik, the "DISPARLON (registered trademark) OX" series manufactured by Kusumoto Chemical Industries, Ltd., and "Polyflow No. 7," "Florene AC-300," and "Florene AC-303" manufactured by Kyoeisha Chemical Co., Ltd. Among these, from the viewpoint of further improving the handleability of the curable composition of the present invention, the dispersibility of the colorant (b) in the curable composition, the discharge stability, and the wettability to the substrate, it is preferred that the curable composition of the present invention further contains a silicone surfactant (e). Commercially available silicone surfactants (e) include, for example, the "KF" series (KF351, KF352, KF352A, KF615, KF54, etc.) manufactured by Shin-Etsu Chemical Co., Ltd., and examples of UV-curable surfactants include BYK-UV3500 (acrylic group-containing polyether-modified polydimethylsiloxane) manufactured by BYK Corporation.When the curable composition of the present invention contains the silicone surfactant (e), the amount thereof is preferably 0.05 to 1 mass %, more preferably 0.07 to 0.8 mass %, based on the total mass of the curable composition of the present invention.

[0059] The curable composition of the present invention may further contain a leveling agent. The leveling agent easily smoothes the surface of the cured product formed from the curable composition, making it easier for the cured product to cure uniformly when irradiated with ultraviolet light, and therefore making it less likely for unevenness to occur in the cured product. Examples of leveling agents include silane compounds, fluorine compounds, acrylic copolymers, and alcohol alkoxylate compounds. The above-mentioned surfactants can also be used as leveling agents.

[0060] As described above, the curable composition of the present invention contains the dispersion of the present invention and a photopolymerization initiator (d). In other words, the curable composition of the present invention contains a polymerizable compound (a) derived from the components of the dispersion of the present invention, a colorant (b) containing at least a titania-based pigment, a dispersant (c), a photopolymerization initiator (d), preferably at least one of a (meth)acrylate (a2) having a hydroxy group or a compound (a3) ​​having two or more (meth)acrylate groups, and a silicone surfactant (e), and more preferably the optional components described above. The content of the colorant (b) in the curable composition of the present invention can be controlled by the amount of the dispersion of the present invention used when preparing the curable composition of the present invention. The content of the colorant (b) is preferably in the range of 30 to 70% by mass, more preferably 35 to 65% by mass, and even more preferably 40 to 60% by mass, based on the total mass of the curable composition of the present invention. Furthermore, the average particle size (D50) of the titania pigment in colorant (b) is preferably 200 to 500 nm, more preferably 200 to 400 nm, and even more preferably 220 to 350 nm. When the content of colorant (b) in the curable composition of the present invention is within the above-mentioned range, the cured product of the curable composition of the present invention tends to have excellent heat resistance, light resistance, moisture resistance, and adhesion to substrates, and in particular, excellent light reflection properties. Furthermore, the storage stability and curability of the curable composition of the present invention also tend to be excellent.

[0061] The curable composition of the present invention may further contain additives such as an ultraviolet absorber, an antioxidant, a surface tension modifier, a discoloration inhibitor, a conductive salt, etc. Furthermore, from the viewpoint of further improving adhesion to substrates such as plastic substrates, the curable composition may also contain a non-reactive resin such as an acrylic resin, an epoxy resin, a terpene phenol resin, or a rosin ester.

[0062] The viscosity of the curable composition of the present invention at 25°C is preferably in the range of 1 to 50 mPa·s, more preferably in the range of 3 to 40 mPa·s, and even more preferably in the range of 5 to 35 mPa·s. The surface tension of the curable composition of the present invention is preferably in the range of 15 to 45 mN / m. When the viscosity and surface tension of the curable composition of the present invention at 25°C are within the above-mentioned ranges, the curable composition of the present invention has excellent dispersibility and is easy to handle, making it easy to apply an inkjet method. This is also preferred from the viewpoint of improving inkjet ejection stability when molding by the inkjet method.

[0063] Here, the curable composition of the present invention may further contain a solvent for the purpose of adjusting the viscosity as described above, etc., within a range that does not impair the effects of the present invention. However, it is preferable that the composition does not contain a solvent. When the composition does not contain a solvent, a drying step or heat treatment (annealing treatment) for removing the solvent can be omitted when curing the curable composition of the present invention. In other words, the manufacturing process can be simplified, and the composition can be applied to a wide range of materials, including inorganic materials such as glass, ceramics, and marble; resin materials such as acrylic resins, vinyl chloride resins, polycarbonate resins, polyester resins, and polyolefin resins; metal materials such as aluminum, iron, copper, and stainless steel; wood; and paper. In addition, the composition has good curability, and the cured product is less likely to generate outgassing due to the solvent, which tends to improve safety. Therefore, it is easy to obtain a cured product of the curable composition of the present invention that can be applied by an inkjet method and does not require annealing treatment.

[0064] The curable composition of the present invention can be produced by supplying the dispersion of the present invention, the photopolymerization initiator (d), the (meth)acrylate (a2) having a hydroxy group, the compound (a3) ​​having two or more (meth)acrylate groups, and various optional components as necessary, and stirring and mixing them using a conventional dispersing machine such as a bead mill or a stirrer. Here, as the dispersing machine, various known and commonly used dispersing machines such as a bead mill, an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a Dyno Mill, a Dispermat, an SC Mill, and a Nanomizer can be used.

[0065] As described above, the curable composition of the present invention is preferably a curable composition that is cured by active energy rays. Examples of active energy rays include visible light, ultraviolet light, infrared light, microwaves, EUV, semiconductor laser light, and excimer lasers (KrF, ArF). Among these active energy rays, the curable composition of the present invention is more preferably a curable composition that is cured by irradiation with light such as ultraviolet light. Examples of light sources that can be used for ultraviolet light include metal halide lamps, xenon lamps, carbon arc lamps, chemical lamps, low-pressure mercury lamps, high-pressure mercury lamps, laser diode (LD) lamps, and UV-LED lamps. From the viewpoint of extremely low heat generation and environmental protection that can accommodate mercury-free trends, it is more preferable to cure the composition by light irradiation using a UV-LED lamp, preferably a UV-LED lamp with a main peak wavelength of approximately 365 to 405 nm that can provide sufficient illuminance. The irradiation energy of light using a UV-LED is 50 to 5,000 mJ / cm. ２ and preferably in the range of 200 to 3000 mJ / cm ２ The range is more preferable.

[0066] When the curable composition of the present invention is used as, for example, a reflector (partition) portion of a light-emitting element, the method for forming the curable composition is not particularly limited. For example, the curable composition of the present invention is applied between light-emitting elements by dropping, using a spin coater, a die coater, a dispenser, an inkjet method, a stencil printing method, a screen printing method, a gravure printing method, or through a mask, to prepare a coating film preferably having the same thickness as the light-emitting element, and then cured; the curable composition of the present invention is preliminarily injected into a mold form by, for example, a dispenser, transfer molding, injection molding, etc., and a lead frame or the like to which a light-emitting element is fixed is immersed therein and then cured; the curable composition of the present invention is injected into a form into which a light-emitting element is inserted and then cured; the curable composition of the present invention is injected into a cup or the like having a light-emitting element arranged at the bottom by a dispenser, etc., and then cured.

[0067] Among these, molding by an inkjet method using an inkjet recording method is preferred. In this case, droplets of the curable composition of the present invention can be deposited on the target with high positional accuracy, thereby improving the accuracy of the shape and dimensions of the cured product. Furthermore, compared to molding by a printing method involving contact, such as screen printing, molding the curable composition of the present invention by an inkjet method allows partition walls to be formed only in the necessary areas, thereby reducing the amount of the curable composition used. In the inkjet method, any of the conventionally known ink ejection methods can be used, such as a method that ejects droplets using the vibration of a piezoelectric element (a recording method using an inkjet head that forms ink droplets by mechanical deformation of an electrostrictive element), a method that uses thermal energy, a method that uses an actuator that uses electrostatic force, or a method that uses a continuous-jet charge-controlled head. Among these, a method using a piezoelectric element is preferred because it is thought to have less adverse effects on the curable composition of the present invention. Furthermore, the curable composition of the present invention can be molded by the inkjet method by previously heating it to reduce its viscosity before ejecting it from the inkjet head.

[0068] A cured product can be produced by discharging the curable composition of the present invention, preferably by an inkjet method, and then curing it by irradiating it with active energy rays, preferably ultraviolet rays. The cured product of the curable composition of the present invention is preferably coated on a substrate and cured to form a film having a thickness of 4 μm or less, and the reflectance of the film is 60% or more for light with a wavelength of 550 nm. The upper limit of this reflectance is not particularly limited and may be 100% or 90%. When the content of colorant (b) in the curable composition of the present invention is within the above-mentioned range, the cured product is likely to have excellent light reflection properties, making it easier to achieve the above-mentioned reflectance. The curable composition of the present invention is suitable as a material for forming a reflector for light-emitting elements such as organic EL elements and LED elements, particularly as a material for forming a partition wall as a reflector. That is, one aspect of the present invention is an LED element containing a cured product of the curable composition of the present invention. In particular, the curable composition of the present invention is suitable as a material for forming a partition wall in a micro LED element.

[0069] Another aspect of the present invention is an electronic device using a cured product of the curable composition of the present invention. By using a cured product of the curable composition of the present invention, the dimensional and shape accuracy of the electronic device can be improved, and the physical properties of the cured product of the curable composition of the present invention can be exhibited. In other words, the present invention is an electronic device in which a light-reflecting white wall is provided in the immediate vicinity of the periphery of a light-emitting element by an inkjet method. Since the lateral light of the light-emitting element can be reflected, light can be used effectively, improving the brightness of the electronic device and reducing energy consumption. Furthermore, a coating film having a thickness of 4 μm or less and having a reflectance of 60% or more at a wavelength of 550 nm can be produced as a cured product from the curable composition of the present invention. In other words, the light-reflecting white wall in the electronic device can be made thinner, leading to thinner, smaller, and lighter electronic devices, and even shortening the manufacturing process of the electronic device. Examples of such electronic devices include displays, projectors, mobile terminals, wristwatches, monitors, and other display devices, touch panels, or lighting devices that use light-emitting elements such as LED elements, micro LED elements, organic EL elements, and organic light-emitting elements (OLEDs); conductive films, organic semiconductor devices, solar cells, organic solar cells, organic photoconductors (OPCs), organic transistors, and CMOS image sensors (CISs).

[0070] The use of the curable composition of the present invention is not limited to the electronic devices described above. The curable composition of the present invention can be used to manufacture various products that utilize its properties, such as a material for forming a filter that can adjust the degree of light scattering and transmission.

[0071] FIG. 1 shows a schematic diagram of an example of the configuration of a micro LED display, an electronic device using a cured product of the curable composition of the present invention, but the present invention is not limited thereto. For example, the curable composition of the present invention can also be applied to displays such as those disclosed in U.S. Patent No. 10,978,626. In FIG. 1 , the micro LED display 100 includes a substrate 2, micro LED elements 1 mounted on the substrate 2, an encapsulant 3, joints 4 between the micro LED elements 1 and metal wiring (not shown) formed on the surface of the substrate 2, and partition walls 5. A black layer 6 covering the top of the partition walls 5 and a solder resist section 7 are provided as needed. The micro LED display 100 includes a plurality of micro LED elements 1, and the plurality of micro LED elements 1 are separated from adjacent micro LED elements 1 on the substrate 2 by partition walls 5. The partition walls 5 are a cured product of the curable composition of the present invention. The substrate 2 can be, for example, a transparent inorganic material such as glass, or a film made of a heat-resistant resin material such as polyethylene naphthalate, polyamide, or polyimide. The thickness of the substrate 2 is not particularly limited, and in the case of a film, a thickness in the range of 25 to 125 μm is usually preferred from the viewpoint of a balance between heat resistance, insulation properties, manufacturing costs, etc. The thickness of the encapsulant 3 in the micro LED display 100 is usually preferably in the range of 5 to 100 μm, more preferably in the range of 5 to 30 μm. By making the encapsulant 3 thinner, the micro LED display 100 can be made thinner and also flexible. The thickness of the encapsulant 3 refers to the distance from the outermost surface of the encapsulant 3 or the interface with the opposing substrate to the outermost surface on the other side of that surface or the opposing interface.

[0072] The micro LED display 100 shown in FIG. 1 can be manufactured, for example, as follows. First, a substrate 2 is prepared. If necessary, a solder resist composition is applied to the entire surface of the substrate 2. After drying, the composition is pattern-exposed and washed with a developer to form a solder resist portion 7 having a pattern in which the micro LED elements 1 can be arranged. A plurality of micro LED elements 1 are mounted on the surface of the substrate 2. Next, a precursor for the partition walls 5 is formed to a predetermined height between the plurality of micro LED elements 1 on the surface of the substrate 2 using the curable composition of the present invention, for example, by an inkjet method. The precursor is then cured by irradiating with ultraviolet light to form the partition walls 5. As described above, the partition walls 5 have a film reflectance of 60% or more at a thickness of 4 μm or less for light with a wavelength of 550 nm. If necessary, a photosensitive material containing a black colorant is applied to the partition walls 5, for example, by an inkjet method, to form a coating. The coating is then cured by irradiating with ultraviolet light to form a black layer 6. The provision of the black layer 6 prevents unintended reflection due to external light. A transparent encapsulant material is then applied, for example, by an inkjet method, to form a coating film that covers the multiple micro LED elements 1, and the coating film is then cured by irradiating it with ultraviolet light to form the encapsulant 3. The ultraviolet light irradiation in the above production may be performed in an oxygen-containing atmosphere, such as the air atmosphere, or in an inert atmosphere, such as a nitrogen atmosphere. The curable composition of the present invention may also be used as a material for forming the solder resist portion 7. In this case, light from below the light-emitting element, such as a micro LED, can be efficiently reflected, allowing efficient use of the light emitted from the LED.

[0073] Although one embodiment of the dispersion, the curable composition, the cured product of the curable composition of the present invention and the method for producing the same, the LED element including the cured product, and the electronic device using the cured product of the present invention have been described above, the present invention is not limited to the configuration of the above-mentioned embodiment. For example, the curable composition of the present invention may have any other optional components in addition to the configuration of the above embodiment, or may be substituted with any optional components that produce the same effect.

[0074] The present invention will be specifically explained below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples, etc. The compounds used in the Examples, etc. are shown below.

[0075] <Polymerizable Compound (a1)> a1-1: Miramer M1130 (trade name, manufactured by MIWON Corporation, trimethylcyclohexyl acrylate (monofunctional (meth)acrylate having an alicyclic skeleton), viscosity (25°C) 3.0 mPa·s) a1-2: Light Acrylate PO-A (trade name, manufactured by Kyoeisha Chemical Co., Ltd., phenoxyethyl acrylate (monofunctional (meth)acrylate having an aromatic ring), viscosity (25°C) 8.3 mPa·s) <Colorant (b)> b-1: PF690 (trade name, manufactured by Ishihara Sangyo Kaisha, Ltd., chlorine-process rutile-type titanium dioxide), average particle size (D50): 250 nm <Dispersant (c)> c-1: "Solsperse (registered trademark) 36000" (manufactured by Lubrizol)

[0076] <(Meth)acrylates (a2) Having a Hydroxy Group> a2-1: 4-HBA (trade name, manufactured by Osaka Organic Chemical Industry Ltd., 4-hydroxybutyl acrylate, viscosity (25°C) 5.5 mPa·s) a2-2: HPA (trade name, manufactured by Osaka Organic Chemical Industry Ltd., hydroxypropyl acrylate), viscosity (25°C) 4.0 mPa·s) <Compounds (a3) ​​Having Two or More (Meth)acrylate Groups> a3-1: Miramer M320 (trade name, manufactured by MIWON Co., Ltd., glycerin propylene oxide adduct triacrylate, viscosity (25°C) 80 to 120 mPa·s) a3-2: ARONIX M-405 (trade name, manufactured by Toagosei Co., Ltd., dipentaerythritol penta- and hexaacrylate, viscosity (25°C) 3700 to 5700 mPa·s) a3-3: EBECRYL80 (trade name, manufactured by Daicel-Allnex Corporation, amine-modified highly reactive polyether acrylate, viscosity (25°C) to 3000 mPa·s) a3-4: EBECRYL7100 (trade name, manufactured by Daicel-Allnex Corporation, amino acrylate, viscosity (25°C) to 1200 mPa·s) a3-5: CN991NS (trade name, manufactured by ARKEMA (manufactured by Sartomer), aliphatic urethane acrylate, viscosity (25°C) 6000 to 12000 mPa·s)

[0077] <Photopolymerization initiators (d)> d-1: TPO-H [(2,4,6-trimethylbenzoyl)diphenylphosphine oxide; acylphosphine oxide photopolymerization initiator, manufactured by IGM Resins B.V.] d-2: Omnirad 819 [phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide; acylphosphine oxide photopolymerization initiator, manufactured by IGM Resins B.V.] d-3: ESACURE3644 [ketocoumarin photopolymerization initiator, manufactured by IGM Resins B.V.] Manufactured by BASF Japan Co., Ltd.] d-4: Irgacure OXE03 [oxime-based photopolymerization initiator, manufactured by BASF Japan Co., Ltd.] d-5: Kayacure DETX-S [2,4-diethylthioxanthen-9-one; thioxanthene-based photopolymerization initiator, manufactured by Nippon Kayaku Co., Ltd.] <Sensitizer> Anthracure UVS-2171 [thioxanthone-based photopolymerization initiator, manufactured by Air Water Inc.]

[0078] <Polymerization inhibitor> Nonflex Alba: 2,5-di-t-butylhydroquinone (manufactured by Seiko Chemical Co., Ltd.) <Silicone surfactant (e)> e-1: KF-54 (polyether-modified polysiloxane, manufactured by Shin-Etsu Chemical Co., Ltd.) e-2: KF-352A (polyether-modified polysiloxane, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0079] 1. Preparation of Dispersions [Example 1-1] 46 parts by mass of polymerizable compound (a1-2), 50 parts by mass of colorant (b-1), and 4 parts by mass of dispersant (c-1) were placed in a bead mill and stirred and mixed to obtain dispersion X1. The viscosity of dispersion X1 at 25°C was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) and found to be 104.3 mPa·s. [Example 1-2] 46 parts by mass of polymerizable compound (a1-1), 50 parts by mass of colorant (b-1), and 4 parts by mass of dispersant (c-1) were placed in a bead mill and stirred and mixed to obtain dispersion X2. The viscosity of dispersion X2 at 25°C was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) and found to be 23.1 mPa·s. Example 1-3: 35.2 parts by mass of polymerizable compound (a1-1), 60 parts by mass of colorant (b-1), and 4.8 parts by mass of dispersant (c-1) were placed in a bead mill and stirred and mixed to obtain dispersion X3. The viscosity of dispersion X3 at 25°C was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) and found to be 35 mPa·s. The D50 of colorant (b-1) in dispersion X3 was also found to be 239 nm. Example 1-4: 24.4 parts by mass of polymerizable compound (a1-1), 70 parts by mass of colorant (b-1), and 5.6 parts by mass of dispersant (c-1) were placed in a bead mill and stirred and mixed to obtain dispersion X4. The viscosity of dispersion X4 at 25°C was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) and found to be 1300 mPa·s. [Example 1-5] 8.2 parts by mass of polymerizable compound (a1-1), 85 parts by mass of colorant (b-1), and 6.8 parts by mass of dispersant (c-1) were placed in a bead mill and stirred to obtain a dispersion, but the viscosity of the mixture increased significantly, making it difficult to handle. [Example 1-6] 37.6 parts by mass of polymerizable compound (a1-1), 60 parts by mass of colorant (b-1), and 2.4 parts by mass of dispersant (c-1) were placed in a bead mill and stirred to obtain dispersion X6. The viscosity of dispersion X6 at 25°C was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) and was found to be 25.0 mPa s. [Example 1-7] 32.4 parts by mass of polymerizable compound (a1-1), 65 parts by mass of colorant (b-1), and 2.6 parts by mass of dispersant (c-1) were placed in a bead mill and stirred to obtain dispersion X4.The viscosity of Dispersion X4 at 25°C was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) and was found to be 35.0 mPa·s. The composition and viscosity of each dispersion are summarized in Table 1.

[0080]

[0081] Examples 1-1 and 1-2 show that the viscosity of the resulting dispersion varies depending on the type and viscosity of the polymerizable compound used. Furthermore, Examples 1-2 to 1-5 show that the content of colorant (b-1) relative to the total dispersion significantly affects the viscosity of the resulting dispersion. Considering the whiteness and light reflectance of the cured product of a curable composition prepared using the dispersion, the content of colorant (b) is in the range of 40 to 80% by mass, preferably 55 to 75% by mass, and more preferably 60 to 75% by mass, from the viewpoint of maintaining the viscosity change of the dispersion within a range that allows for good handleability. Examples 1-6 and 1-7 also show that the content of dispersant (c) relative to the total dispersion significantly affects the viscosity of the resulting dispersion. The content of the dispersant (c) in the entire dispersion is preferably in the range of 2 to 10 mass %, but in consideration of the good stability and low viscosity of the dispersion, it is found that the content of the dispersant (c) is particularly preferably in the range of 2 to 6 mass %.

[0082] 2. Preparation of Curable Composition [Example 2-1] 77.50 parts by mass of the dispersion X3 obtained in Example 1-3, 2.80 parts by mass of polymerizable compound (a1-1), 10.82 parts by mass of (a2-1) as (meth)acrylate (a2) having a hydroxy group, 4.70 parts by mass of (a3-1) as compound (a3) ​​having two or more (meth)acrylate groups, 0.80 parts by mass of (d-1) and 3.20 parts by mass of (d-2) as photopolymerization initiator (d), 0.09 parts by mass of polymerization inhibitor, and 0.09 parts by mass of silicone surfactant (e-1) were placed in a container and stirred and mixed to prepare curable composition 1. Table 1 shows the content mass ratio of each component of curable composition 1 as a percentage. [Examples 2-2 to 2-6] Dispersion X3 obtained in Example 1-3, the polymerizable compound (a1), the (meth)acrylate having a hydroxy group (a2), the compound having two or more (meth)acrylate groups (a3), the photopolymerization initiator (d), the polymerization inhibitor, and the silicone surfactant (e) shown in Table 1 were placed in a container and stirred and mixed to prepare curable compositions 2 to 6 having the content ratios of each component shown in Table 1. [Examples 2-7 to 2-8] Dispersion X7 obtained in Example 1-7, the polymerizable compound (a1), the (meth)acrylate having a hydroxy group (a2), the compound having two or more (meth)acrylate groups (a3), the photopolymerization initiator (d), the polymerization inhibitor, and the silicone surfactant (e) shown in Table 1 were placed in a container and stirred and mixed to prepare curable compositions 7 to 8 having the content ratios of each component shown in Table 1. [Examples 2-9 to 2-10] Dispersion X7 obtained in Example 1-7, the polymerizable compound (a1), the (meth)acrylate having a hydroxy group (a2), the compound having two or more (meth)acrylate groups (a3), the photopolymerization initiator (d), the sensitizer, the polymerization inhibitor, and the silicone surfactant (e) shown in Table 1 were placed in a container and mixed with stirring to prepare curable compositions 9 to 10 having the content ratios of each component shown in Table 1.

[0083] 3. Evaluation 3-1. Viscosity of curable composition Measurement was performed at a temperature of 25°C using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.). The viscosity of each curable composition is shown in Table 2. When the viscosity is 50 mPa·s or less, preferably 30 mPa·s or less, and more preferably 25 mPa·s or less, good ejection conditions are likely to be obtained in the inkjet method. Furthermore, when each curable composition was stored at -20 to 20°C, there was little change in viscosity, and all had good storage stability.

[0084] 3-2. Light reflectance of cured product (1) The curable composition obtained in each example was applied to a non-alkali glass substrate (35 mm length × 35 mm width, 0.7 mm thickness) using a spin coater to form a coating film with a thickness of 4 μm. This coating film was then irradiated with UV-LED light at a peak wavelength of 365 nm and a peak irradiance of 1000 mW / cm using a UV-LED irradiation device (manufactured by ITEC Systems Co., Ltd.). ２ , cumulative light intensity 3 J / cm ２ The coatings were cured by irradiating them with ultraviolet light under the conditions of (a) to (b) to produce cured products (cured coating films). (2) The light reflectance of each of the cured products obtained above in the wavelength range of 400 to 800 nm was measured using an integrating sphere with a spectrometer (Hitachi spectrophotometer "U-4100"). The measured light reflectance of only the alkali-free glass substrate used in producing the cured products was used as the reference value. Each of the cured products was almost white. The light reflectance values ​​of each of the cured products at 550 nm are shown in Table 2.

[0085] 3-3. Adhesion of cured products In the same manner as in 3-2(1), cured products (cured coating films) of the curable compositions obtained in each production example were prepared, and after making grid-like cuts with a cutter, adhesive tape (manufactured by Nichiban Co., Ltd.) was attached to the surface. The adhesive tape was then peeled off and the state of the cured coating remaining on the substrate was visually observed, and adhesion was evaluated according to the following criteria. [Evaluation criteria] A: No peeling of the cured coating film was observed. B: Partial peeling was observed. C: Significant peeling was observed.

[0086] 3-4. Moisture Resistance of Cured Products Cured products (cured coating films) of the curable compositions obtained in each Production Example were prepared in the same manner as in 3-2(1), and each cured product was placed in a thermostatic chamber at 85°C and a relative humidity of 85% for 500 hours. The cured products were removed and allowed to cool naturally to 25°C, after which the presence or absence of surface non-uniformity was observed under a microscope (100x magnification), and the moisture resistance was evaluated according to the following criteria. [Evaluation Criteria] A: No change B: Non-uniformity on the surface of the cured product was observed under a microscope at 100x magnification C: Non-uniformity on the surface of the cured product was visible without the need for microscopic observation

[0087] The mass ratio of each component contained in each curable composition and the results of the above evaluations are summarized in Table 2. Table 2 also shows, for each curable composition, the total proportion of the polymerizable compound (a1) and the polymerizable compound (a2) relative to the mass of the entire curable composition (monofunctional compound proportion; mass%), the proportion of the compound having two or more (meth)acrylate groups (polyfunctional compound proportion; mass%), and the proportion of the photopolymerization initiator (d) relative to the mass of the entire curable composition (photopolymerization initiator (d) proportion; mass%).

[0088]

[0089] These results show that a dispersion containing a polymerizable compound (a1), a titania-based pigment as a colorant (b), and a dispersant (c), as well as a curable composition containing a photopolymerization initiator (d), a (meth)acrylate having a hydroxy group (a2), and a compound having two or more (meth)acrylate groups (a3), has low viscosity, is easy to handle, and has excellent storage stability. The cured product also has a well-balanced excellent curability, light reflectance, adhesion to a substrate, and moisture resistance.

[0090] The curable composition of the present invention has excellent curability and can be used to form a molded product by an inkjet method, and the resulting cured product has excellent heat resistance, light resistance, moisture resistance, and light reflection properties. The curable composition of the present invention is particularly suitable as a composition for forming a reflector for a light-emitting element, and is useful as a reflector (partition wall) material for a micro LED element. Furthermore, electronic devices using a cured product of the curable composition of the present invention are useful as various display devices, touch panels, or lighting; conductive films, organic semiconductor devices, solar cells, organic solar cells, organic photoconductors (OPCs), organic transistors, CMOS image sensors (CISs), etc.

[0091] REFERENCE SIGNS LIST 1 Micro LED element 2 Substrate 3 Sealant 4 Joint 5 Partition 6 Black layer 7 Solder resist 100 Micro LED display

Claims

1. A dispersion containing a polymerizable compound (a), a colorant (b), and a dispersant (c), wherein the colorant (b) contains at least a titania-based pigment, the content of the colorant (b) with respect to the whole dispersion is in the range of 40 to 80% by mass, and the dispersion does not contain a solvent.

2. The dispersion according to claim 1, wherein the polymerizable compound (a) contains a polymerizable compound having a viscosity of less than 9 mPa·s at 25°C.

3. The dispersion according to claim 1 or 2, wherein the polymerizable compound (a) contains a monofunctional (meth)acrylate (a1).

4. The dispersion according to claim 3, wherein the monofunctional (meth)acrylate (a1) contains a monofunctional (meth)acrylate having an alicyclic skeleton.

5. The dispersion according to claim 1, wherein the average particle diameter (D50) of the titania-based pigment in the colorant (b) is 200 to 500 nm.

6. A curable composition containing the dispersion according to claim 1 and a photopolymerization initiator (d).

7. The curable composition according to claim 6, further containing a (meth)acrylate (a2) having a hydroxy group.

8. The curable composition according to claim 6, further containing a compound (a3) having two or more (meth)acrylate groups.

9. The curable composition according to claim 6, wherein the photopolymerization initiator (d) includes an oxime-based photopolymerization initiator.

10. The curable composition according to claim 6, further containing a silicone-based surfactant (e).

11. The curable composition according to claim 6, having a viscosity of 1 to 50 mPa·s at 25°C.

12. The curable composition according to claim 6, wherein the content of the colorant (b) is 30 to 70% by mass with respect to the total mass of the curable composition.

13. The curable composition according to claim 6, wherein the average particle diameter (D50) of the titania-based pigment in the colorant (b) is 200 to 500 nm.

14. The curable composition according to claim 6, which is an active energy ray curable composition.

15. The curable composition according to claim 6, which does not contain a solvent.

16. A cured product of the curable composition according to any one of claims 6 to 15.

17. The cured product according to claim 16, wherein the reflectance of a film having a thickness of 4 μm or less formed by coating and curing on a substrate is 60% or more for light having a wavelength of 550 nm.

18. A method for producing a cured product, comprising a step of curing the curable composition according to any one of claims 6 to 15 by irradiating it with active energy rays.

19. The production method according to claim 18, wherein the curable composition is formed by an inkjet method.

20. An electronic device using a cured product of the curable composition according to any one of claims 6 to 15.

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