Ink composition, cured product, and image display device

Abstract

[Problem] To provide an ink composition or the like useful for manufacturing an image display device or the like. [Solution] One embodiment of the present invention provides an ink composition. This ink composition contains a reflective material (A), a cationically polymerizable compound (B), and a photoacid generator (C). The cationically polymerizable compound (B) contains a metal element-containing compound (B1) that has a cationically polymerizable group and a hydrolyzable group.

Description

Ink composition, cured product, and image display device

[0001] The present invention relates to an ink composition, a cured product, and an image display device.

[0002] In recent years, image display devices capable of displaying clearer images have been developed. For example, Patent Document 1 discloses a display module in which multiple LED chips are mounted on a substrate. Patent Document 1 also discloses a structure in which light-reflecting walls are provided between the LED chips to prevent interference between the output light of the LED chips (see Patent Document 1;

[0043] , FIG. 4, etc.).

[0003] Japanese Patent Application Laid-Open No. 2018-026517

[0004] However, there is still a demand for technological development to improve the brightness of light emitted by image display devices.

[0005] In view of the above circumstances, the present invention provides an ink composition and the like that is useful for producing an image display device and the like.

[0006] According to one aspect of the present invention, there is provided an ink composition comprising a reflective material (A), a cationically polymerizable compound (B), and a photoacid generator (C). The cationically polymerizable compound (B) comprises a metal element-containing compound (B1) having a cationically polymerizable group and a hydrolyzable group.

[0007] According to the above aspect, an ink composition or the like useful for producing an image display device or the like is provided.

[0008] 1 is a cross-sectional view of an image display device in which a cured product of the ink composition according to the present embodiment is used as a partition wall; FIG. 2 is a cross-sectional view of an image display device in which a cured product of the ink composition according to the present embodiment is used as a partition wall; and FIG. 3 is a cross-sectional view of an image display device in which a cured product of the ink composition according to the present embodiment is used as a partition wall.

[0009] Hereinafter, embodiments of the present invention will be described. Note that the various features shown in the following embodiments can be combined with each other. In addition, "~" in this specification means "above" through "below" unless otherwise specified.

[0010] <Ink composition> The ink composition of this embodiment is as follows. The ink composition comprises a reflective material (A), a cationically polymerizable compound (B), and a photoacid generator (C), wherein the cationically polymerizable compound (B) comprises a metal element-containing compound (B1) having a cationically polymerizable group and a hydrolyzable group. The components constituting the ink composition of this embodiment, a method for producing the ink composition, uses, etc. will be described below.

[0011] [Reflecting material (A)] The ink composition of this embodiment contains a reflecting material (A). As will be described later, the ink composition of this embodiment is typically used when forming partition walls of an image display device equipped with light-emitting elements. Here, by including the reflecting material (A) in the ink composition in this manner, the partition walls reflect light emitted by the light-emitting elements, which can contribute to improving the brightness of the image display device.

[0012] The reflective material (A) may be appropriately selected from known materials capable of reflecting light. From the viewpoint of availability, the reflective material (A) preferably contains a white pigment or a metallic pigment.

[0013] Examples of white pigments that can be used include titanium oxide (titanium white), zinc oxide (zinc white), white lead, basic lead sulfate, lead sulfate, lithopone, zinc sulfide, antimony white, barium sulfate, calcium carbonate, aluminum oxide, kaolin, and talc. On the other hand, examples of metal pigments that can be used include simple metals and various alloys. Examples of metal elements that can form these metals and various alloys include indium, aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, titanium, iron, and copper. From the viewpoint of high light reflectivity, the metal pigment preferably contains indium or aluminum. Furthermore, from the viewpoint of improving the coatability of the ink composition, the metal pigment preferably contains indium.

[0014] Alternatively, the reflective material (A) may be a material obtained by adhering a metal compound such as titanium oxide to the surface of particles that do not reflect light.

[0015] In this embodiment, the reflective material (A) may have a particulate shape. The particle shape may be polyhedral, spherical, scale-like, or the like. When the reflective material (A) has such a particulate shape, it is preferable that its average particle diameter be controlled. As an example, the Z-average particle diameter of the reflective material (A) may be 100 nm or more and 1000 nm or less, 150 nm or more and 800 nm or less, or 180 nm or more and 600 nm or less. Setting the particle diameter of the reflective material (A) within such a range can contribute to improving the balance between the coatability of the ink composition and the reflective properties of the resulting cured product. The Z-average particle diameter can be measured using a Zetasizer Nano ZS (manufactured by Malvern Instruments) or the like.

[0016] In the ink composition of this embodiment, the content of the reflective material (A) can be appropriately set depending on the application, etc. Meanwhile, the content of the reflective material (A) is preferably 0.5 parts by mass or more and 50 parts by mass or less, more preferably 1 part by mass or more and 40 parts by mass or less, and even more preferably 2 parts by mass or more and 30 parts by mass or less, when the total solid content of the ink composition is 100 parts by mass. By setting the content of the reflective material (A) within such a range, it is possible to ensure the curability of the ink composition while achieving higher reflective properties for the resulting cured product.

[0017] [Cationically Polymerizable Compound (B)] The ink composition of this embodiment contains a cationically polymerizable compound (B). This cationically polymerizable compound (B) is a compound that contains a cationically polymerizable group in its chemical structure. Specific examples of this cationically polymerizable group include cyclic ether groups such as epoxy groups and oxetanyl groups, as well as vinyl ether groups. Furthermore, the cationically polymerizable compound (B) of this embodiment includes compounds such as epoxy compounds, oxetane compounds, and oxolane compounds (e.g., tetrahydrofuran, substituted tetrahydrofuran, etc.).

[0018] The ink composition of this embodiment contains, as the cationically polymerizable compound (B), a metal element-containing compound (B1) having a cationically polymerizable group and a hydrolyzable group. Note that the ink composition of this embodiment may further contain another cationically polymerizable compound (B2) that does not fall under the category of the metal element-containing compound (B1). These components will be further described below.

[0019] The metal element-containing compound (B1) in this embodiment contains the above-mentioned cationically polymerizable group and a metal element in its chemical structure. Specifically, this metal element-containing compound (B1) can be represented by the following structural formula (1): M(R)x(X)y (1) In structural formula (1), M is a metal element, R is an organic group containing a cationically polymerizable group in its structure, and M is bonded to a carbon atom of R. X is a group selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, and a phenoxy group. x and y are integers of 1 or more, and the sum of x and y is the bonding number of M.

[0020] Examples of the metal element include silicon, aluminum, titanium, zirconium, tin, lead, and boron. Among these, silicon is preferred as the metal element from the viewpoints of availability and ease of handling. That is, the metal element-containing compound (B1) is preferably a silicon-containing compound. As described above, the metal element-containing compound (B1) contains a cationically polymerizable group in the structure of R. In this regard, from the viewpoint of high reactivity, it is preferred that the structure of R contains an epoxy group. That is, the cationically polymerizable group possessed by the metal element-containing compound (B1) is preferably an epoxy group. The cationically polymerizable group contained in the structure of R may be an oxetanyl group. When X is an alkoxy group, the alkoxy group has, for example, 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 4 carbon atoms. When X is a phenoxy group, the hydrogen atoms of the benzene ring constituting the phenoxy group may be substituted with various substituents. When M is silicon, an example embodiment is one in which x is 1 or 2 and y is 2 or 3.

[0021] The metal element-containing compound (B1) of this embodiment undergoes cationic polymerization due to an acid generated by the photoacid generator (C) described below, and the metal element contained in the structure of the compound (B1) can form a chemical bond with the surface of a substrate to which the ink composition is applied. This contributes to the ink composition of this embodiment exhibiting high substrate adhesion.

[0022] Particularly preferred examples of the metal element-containing compound (B1) include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-[(3-ethyloxetan-3-yl)methoxy]propyl(trimethoxy)silane, 3-[(3-ethyloxetan-3-yl)methoxy]propyl(triethoxy)silane, 3-[(3-methyloxetan-3-yl)methoxy]propyl(trimethoxy)silane, and 3-[(3-methyloxetan-3-yl)methoxy]propyl(triethoxy)silane.

[0023] Furthermore, other cationically polymerizable compounds (B2) that may be contained in the ink composition of this embodiment are preferably epoxy compounds, oxetane compounds, vinyl ether compounds, etc., because of their easy availability and high reactivity. Note that these other cationically polymerizable compounds do not contain the above-mentioned metal elements in their chemical structures.

[0024] The cationically polymerizable compound (B) may further contain an epoxy compound as another cationically polymerizable compound (B2) that does not fall under the category of the metal element-containing compound (B1). The epoxy compound is a compound having an epoxy group, and examples thereof include glycidyl ether-type epoxy compounds and alicyclic epoxy compounds. The epoxy compound may have one or more epoxy groups, but may also contain a compound having two or more epoxy groups. That is, the epoxy compound in the other cationically polymerizable compound (B2) of this embodiment may be a monofunctional epoxy compound or a polyfunctional epoxy compound.

[0025] Specific examples of the epoxy compound include phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4,3',4'-diepoxybicyclohexyl, 1,2-epoxy 4-vinylcyclohexane, ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl, 3,4-epoxycyclohexanecarboxylate, limonene dioxide, 2,2-bis(4-glycidyloxyphenyl)propane, 2-[4-(2,3-epoxypropionyl)methyl]propane, and the like. a mixture of 1,3-bis[4-[1-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-([2,3-epoxypropoxy]phenyl)]ethyl]phenyl]propane and 1,3-bis[4-[1-[4-(2,3-epoxypropoxy)phenyl]-1-[4-[1-[4-(2,3-epoxypropoxy)phenyl]-1-methylethyl]phenyl]ethyl]phenoxy]-2-propanol, and 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-([2,3-epoxypropoxy]phenyl)]ethyl]phenyl]propane.

[0026] The epoxy compound may be any of an epoxy monomer, an epoxy oligomer, and an epoxy resin, and commercially available products such as those listed below may also be used. That is, polyfunctional epoxy monomers such as CELLOXIDE (registered trademark) CEL2021P, CEL2000, and CEL8000 (manufactured by Daicel Corporation) may be used as the epoxy compound. Furthermore, resins such as glycidyl ether epoxy resins such as TECHMORE VG3101L (manufactured by Printec Co., Ltd.), EPPN-501H and 502H (manufactured by Nippon Kayaku Co., Ltd.), and JER1032H60 (manufactured by Mitsubishi Chemical Corporation); bisphenol A novolac epoxy resins such as JER157S65 and 157S70 (manufactured by Mitsubishi Chemical Corporation); and phenol novolac epoxy resins such as EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), JER152, and 154 (manufactured by Mitsubishi Chemical Corporation) may also be used as the epoxy compound in this embodiment.

[0027] The cationically polymerizable compound (B) may further include an oxetane compound as another cationically polymerizable compound (B2) that does not fall under the category of the metal element-containing compound (B1). The oxetane compound may have one or more oxetanyl groups, but may also include a compound having two or more oxetanyl groups. That is, the oxetane compound in the other cationically polymerizable compound (B2) of this embodiment may be a monofunctional oxetane compound or a polyfunctional oxetane compound.

[0028] Examples of the oxetane compound include 2-ethylhexyloxetane, 3-ethyl-3-ethoxymethyloxetane, 3-ethyl-3-butoxymethyloxetane, 3-ethyl-3-hexyloxymethyloxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, [(1-ethyl-3-oxetanyl)methoxy]cyclohexane, 3-ethyl-3-(phenoxymethyl)oxetane, 3-ethyl-3-methoxymethyloxetane, oxetane alcohol, 3-ethyl bis[(1-ethyl-3-oxetanyl)methoxy]cyclohexane, bis[(1-ethyl-3-oxetanyl)methoxy]norbornane, 1,4-bis((1-ethyl-3oxetanyl)methoxy)benzene, 1,3-bis((1-ethyl-3oxetanyl)methoxy)benzene, 4,4'-bis((3-ethyl-3oxetanyl)methoxy)biphenyl, and xylylene bisoxetane.

[0029] The cationically polymerizable compound (B) may further contain a vinyl ether compound as another cationically polymerizable compound (B2) that does not fall under the category of the metal element-containing compound (B1). Examples of the vinyl ether compound include di- or trivinyl ether compounds such as 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; and monovinyl ether compounds such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-o-propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

[0030] When the ink composition of this embodiment contains another cationically polymerizable compound (B2), the other cationically polymerizable compound (B2) preferably contains a compound containing one cationically polymerizable group in its chemical structure. Typically, the ink composition of this embodiment preferably contains a monofunctional epoxy compound or a monofunctional oxetane compound. These compounds are less likely to undergo cure shrinkage during curing, thereby contributing to the substrate adhesion of the cured film. For example, the content of the monofunctional epoxy compound or monofunctional oxetane compound may be 5 parts by mass or more, 20 parts by mass or more, or 40 parts by mass or more, based on 100 parts by mass of the other cationically polymerizable compounds (B2). There is no particular upper limit. All of the other cationically polymerizable compounds (B2) may be monofunctional epoxy compounds or monofunctional oxetane compounds, and the content of the monofunctional epoxy compound or monofunctional oxetane compound may be adjusted to 85 parts by mass or less, based on 100 parts by mass of the other cationically polymerizable compounds (B2).

[0031] Furthermore, when the ink composition of this embodiment contains another cationically polymerizable compound (B2), it is preferable that the other cationically polymerizable compound (B2) consists of two or more components. By adopting such a configuration, it becomes easier to realize an ink composition that has an excellent balance between curability, adhesion, and hardness of the cured film.

[0032] In the ink composition of this embodiment, the content of the cationically polymerizable compound (B) is preferably 5 parts by mass or more and 96 parts by mass or less, more preferably 7 parts by mass or more and 95 parts by mass or less, and even more preferably 10 parts by mass or more and 94 parts by mass or less, when the total solid content of the ink composition is 100 parts by mass. By setting the content of the cationically polymerizable compound (B) within this range, it is possible to ensure the storage stability of the ink composition while achieving a high level of curability of the ink composition.

[0033] In the ink composition of this embodiment, the content of the metal element-containing compound (B1) is preferably 1.5 parts by mass or more and 80 parts by mass or less, based on 100 parts by mass of the total solid content of the ink composition. By setting the content of the metal element-containing compound (B1) within this range, it is possible to achieve higher substrate adhesion compared to conventional techniques. Furthermore, the content of the metal element-containing compound (B1) is more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, and particularly preferably 10 parts by mass or more, based on 100 parts by mass of the total solid content of the ink composition. By setting the content of the metal element-containing compound (B1) within this range, it is possible to achieve a higher level of substrate adhesion. From the perspective of reducing production costs, the content of the metal element-containing compound (B1) can also be set to 78 parts by mass or less, 70 parts by mass or less, 60 parts by mass or less, or 55 parts by mass or less, based on 100 parts by mass of the total solid content of the ink composition.

[0034] In the ink composition of this embodiment, the content of the other cationically polymerizable compound (B2) is preferably 5 parts by mass or more and 80 parts by mass or less, more preferably 10 parts by mass or more and 78 parts by mass or less, and even more preferably 15 parts by mass or more and 75 parts by mass or less, relative to 100 parts by mass of the total solid content of the ink composition. By setting the content of the other cationically polymerizable compound (B2) within this range, good curability can be exhibited, and the film quality of the resulting reflective member can be improved.

[0035] [Photoacid Generator (C)] The ink composition of this embodiment contains a photoacid generator (C). That is, when the ink composition of this embodiment is exposed to light, this photoacid generator (C) generates an acid, which promotes the polymerization reaction of the cationically polymerizable compound (B). This photoacid generator (C) may be appropriately selected from known materials, but preferably, the photoacid generator (C) contains a sulfonium salt compound (C1). By using the sulfonium salt compound (C1) in this manner, curing of the ink composition by light proceeds efficiently.

[0036] The sulfonium salt compound (C1) is a salt of a sulfonium cation and an anion.

[0037] Here, examples of the sulfonium cation include triphenylsulfonium, (4-tert-butoxyphenyl)diphenylsulfonium, bis(4-tert-butoxyphenyl)phenylsulfonium, tris(4-tert-butoxyphenyl)sulfonium, (3-tert-butoxyphenyl)diphenylsulfonium, bis(3-tert-butoxyphenyl)phenylsulfonium, tris(3-tert-butoxyphenyl)sulfonium, (3,4-ditert-butoxyphenyl)diphenylsulfonium, bis(3,4-ditert-butoxyphenyl)phenylsulfonium, tris(3,4-ditert-butoxyphenyl)sulfonium, diphenyl(4-(phenyl) Examples of the sulfonium nitrile include (4-tert-butoxycarbonylmethyloxyphenyl)bis(4-phenyl)sulfonium, (4-tert-butoxycarbonylmethyloxyphenyl)diphenylsulfonium, tris(4-tert-butoxycarbonylmethyloxyphenyl)sulfonium, (4-tert-butoxyphenyl)bis(4-dimethylaminophenyl)sulfonium, tris(4-dimethylaminophenyl)sulfonium, 2-naphthyldiphenylsulfonium, dimethyl 2-naphthylsulfonium, 4-hydroxyphenyldimethylsulfonium, 4-methoxyphenyldimethylsulfonium, trimethylsulfonium, 2-oxocyclohexylcyclohexylmethylsulfonium, trinaphthylsulfonium, and tribenzylsulfonium.

[0038] The anion is BF ４ － , P.F. ６ － , SbF ６ － , [BX ４ ] － (X represents a phenyl group substituted with at least two fluorine or trifluoromethyl groups), [PF ｎ Y ６－ｎ ] －(Y represents a fluorinated alkyl group having 1 to 9 carbon atoms or a fluorinated phenyl group, and n is an integer of 1 to 6), sulfonate anions, etc.

[0039] Other compounds that can be used as the photoacid generator (C) (also referred to as other photoacid generators (C2)) include ionic photoacid generators other than sulfonium salts, nonionic photoacid generators, etc. Specific examples of the other photoacid generators (C2) include phenyldiazonium salts of boron tetrafluoride, diphenyliodonium salts of phosphorus hexafluoride, diphenyliodonium salts of antimony hexafluoride, diphenyliodonium salts of tetrakis(pentafluorophenyl)boron, mixtures of aluminum acetylacetone salts and orthonitrobenzylsilyl ether, phenylthiopyridium salts, phosphorus hexafluoride allene-iron complexes, sulfonyldiazomethane, N-sulfonyloxyimide-type photoacid generators such as phthalic acid imide-type photoacid generators and naphthalimide-type photoacid generators, and oxime-O-sulfonate-type photoacid generators.

[0040] In the ink composition of this embodiment, the photoacid generator (C) preferably contains a compound having a peak wavelength of 280 nm or more. The use of such a compound facilitates the formation of a reflective member in an industrially advantageous manner. This compound having a peak wavelength of 280 nm or more may be a compound corresponding to the sulfonium salt compound (C1) described above, or another compound corresponding to the photoacid generator (C2).

[0041] In the ink composition of this embodiment, the content of the photoacid generator (C) is preferably 0.1 parts by mass or more and 15 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, and even more preferably 1 part by mass or more and 8 parts by mass or less, when the total solid content of the ink composition is taken as 100 parts by mass. By setting the content of the photoacid generator (C) within this range, it is possible to ensure the storage stability of the ink composition while achieving high levels of curability and adhesion of the ink composition.

[0042] The mass proportion of the sulfonium salt compound (C1) in the entire photoacid generator (C) is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and particularly preferably 98 mass% or more. Furthermore, the photoacid generator (C) may be substantially composed of only the sulfonium salt compound (C1). This makes it easier to achieve the above-mentioned effects.

[0043] [Sensitizer (D)] The ink composition of this embodiment may contain a sensitizer (D). That is, by containing the sensitizer (D) in this manner, the ink composition of this embodiment can ensure good curability even while containing the reflective material (A).

[0044] In this embodiment, the sensitizer (D) preferably contains a compound (D1) containing an anthracene skeleton, which can ensure good curability of the ink composition.

[0045] Examples of the compound (D1) containing an anthracene skeleton include anthracene, 9-anthracenemethanol, 9-anthracenecarboxylic acid, 9,10-diphenylanthracene, 9,10-bis(phenylethynyl)anthracene, 2-methoxyanthracene, 1,5-dimethoxyanthracene, 1,8-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dibutoxyanthracene, 9,10-bis(octanoyloxy)anthracene, 6-chloroanthracene, and 1,5-dichloroanthracene. These may be used alone or in combination.

[0046] The ink composition of this embodiment may also contain another sensitizer (D2) that does not fall under the category of the compound (D1) containing an anthracene skeleton. Examples of the other sensitizer (D2) include aromatic nitro compounds, coumarins, thiazolines, oxazolines, thioxanthones, benzothiazole, nitroaniline, nitroacenaphthene, benzoin alkyl ethers, N-alkylated phthalones, naphthalenes, chrysene, pyrene, benzopyran, azoindolizines, furocoumarins, phenothiazine, benzo[c]phenothiazine, 7-H-benzo[c]phenothiazine, triphenylene, 1,3-dicyanobenzene, and phenyl-3-cyanobenzoate.

[0047] In the ink composition of this embodiment, the content of the sensitizer (D) is preferably 0.05 parts by mass or more and 6 parts by mass or less, more preferably 0.08 parts by mass or more and 4 parts by mass or less, and even more preferably 0.1 parts by mass or more and 2 parts by mass or less, when the total solid content of the ink composition is taken as 100 parts by mass. By setting the content of the sensitizer (D) within this range, it is possible to ensure the storage stability of the ink composition while achieving a high level of curability of the ink composition.

[0048] The mass proportion of the anthracene skeleton-containing compound (D1) in the entire sensitizer (D) is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and particularly preferably 98 mass% or more. Alternatively, the sensitizer (D) may be essentially composed of the anthracene skeleton-containing compound (D1) alone. This makes it easier to achieve the above-described effects.

[0049] [Solvent (S)] The ink composition of this embodiment may contain a solvent (S) as a volatile component. By containing the solvent (S) in this manner, the ink composition of this embodiment is more likely to have excellent coatability. This solvent (S) can be one or more solvents known in the ink field. Note that, as the organic solvent, for example, one or more of alcohol-based solvents, ketone-based solvents, ester-based solvents, ether-based solvents, ether ester-based solvents, glycol ether-based solvents, amide-based solvents, carbonate-based solvents, etc. can be used. Note that, in this specification, the solvent (S) refers to a component that does not fall under the above-mentioned components (A) to (D) and has a boiling point of 250°C or less at 1 atmosphere.

[0050] Examples of alcohol-based solvents include methanol, ethanol, isopropanol, 1-butanol, tertiary butanol, isobutanol, diacetone alcohol, and 3-methoxy-3-methyl-1-butanol. Examples of ketone-based solvents include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, and diisobutyl ketone. Examples of ester-based solvents include ethyl acetate, methyl acetate, butyl acetate, methoxybutyl acetate, cellosolve acetate, amyl acetate, normal propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, and butyl lactate. Examples of ether-based solvents include dibutyl ether, tetrahydrofuran, and dioxane. Examples of ether ester-based solvents include 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, and methyl methoxypropionate. Examples of glycol ether solvents include ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, and butyl cellosolve (ethylene glycol monobutyl ether). Examples of amide solvents include N-methylpyrrolidone and N,N-dimethylformamide. Examples of carbonate solvents include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0051] The content of the solvent (S) in the ink composition of this embodiment is arbitrary. For example, the content of the solvent (S) may be set so that the solids concentration of the ink composition is 70% by mass or more, the content of the solvent (S) may be set so that the solids concentration of the ink composition is 80% by mass or more, or the content of the solvent (S) may be set so that the solids concentration of the ink composition is 90% by mass or more. Here, the "solids concentration" refers to the proportion of all components of the ink composition excluding the solvent (S) from the entire ink composition. In other words, in this specification, the solids content refers to the portion of the ink composition excluding components that do not fall under the above-mentioned components (A) to (D) and have a boiling point of 250°C or less at 1 atmosphere. The ink composition of this embodiment may also be configured to be substantially free of the above-mentioned solvent (S). In this specification, the term "substantially free" is used to exclude embodiments in which a specific component is intentionally added, but is used to allow embodiments in which it is unavoidable to avoid the inclusion of a specific component in the manufacturing process. In an exemplary process, the solvent (S) needs to be removed by heating as a step prior to exposing the ink composition of this embodiment to light. When the content of the solvent (S) in the ink composition is controlled, this is advantageous in that such a heating step can be omitted.

[0052] [Other Additives] The ink composition of this embodiment may contain additional components other than the components described above. These additional components include surface conditioners, which include silicone compounds, waxes, antifoaming agents, leveling agents, and anti-foaming agents (components that break down air trapped during coating).

[0053] Examples of the surface conditioner include the Acronal (registered trademark) series (manufactured by BASF, (meth)acrylic resin type) such as Acronal 4F, the BYK series (manufactured by BYK), the Polyflow series (manufactured by Kyoeisha Chemical Co., Ltd.), the Resiflow series (manufactured by ESTRON CHEMICAL), and the Modaflow series (manufactured by Monsanto).

[0054] The ink composition of this embodiment may contain only one type of surface conditioner, or may contain two or more types of surface conditioner. The amount of surface conditioner in the ink composition of this embodiment is not particularly limited and may be adjusted appropriately in consideration of other performance factors.

[0055] The ink composition of this embodiment may contain additives other than the various components described above, such as a filler, a coupling agent, an antioxidant, a viscosity modifier, a storage stabilizer, a dispersant, etc. The amounts of these agents in the ink composition of this embodiment are not particularly limited and may be adjusted as appropriate in consideration of the balance with other performance properties.

[0056] [Method for Producing Ink Composition] The ink composition of this embodiment is typically produced by mixing the above-described components.

[0057] To give a more specific example, the ink composition of this embodiment can be produced by the following procedure: (Step 1): A dispersion containing the reflective material (A) is obtained by dispersing the reflective material (A) in a dispersion medium. (Step 2): The obtained dispersion is mixed with other materials.

[0058] That is, in the above-described method, a dispersion containing the reflective material (A) is first obtained in (Step 1), and then this dispersion is mixed with other materials to obtain the desired ink composition. The dispersion medium used to obtain the dispersion may be any of various materials capable of dispersing the reflective material (A). For example, when the cationically polymerizable compound (B) is liquid, the cationically polymerizable compound (B) may also be used as the dispersion medium. Furthermore, to improve the dispersibility of the dispersion, a dispersant (also referred to as an anti-settling agent or dispersion aid) may be added. Known dispersants may be used, but typically, polymer-type dispersants are used. Commercially available dispersants may be used, and specific examples include the FLOWRENE DOPA series (manufactured by Kyoeisha Chemical Co., Ltd.), the SOLSPERSE series (manufactured by The Lubrizol Nippon Corporation), the AJISPER series (manufactured by Ajinomoto Fine-Techno Co., Ltd.), the Disper BYK series (manufactured by BYK), and the DISPALON series (manufactured by Kusumoto Chemical Co., Ltd.). The blending ratio of the dispersant in the dispersion can be appropriately set depending on the type of dispersant, but is, for example, in the range of 1 to 100 parts by mass, preferably 3 to 70 parts by mass, per 100 parts by mass of the reflective material (A).

[0059] Subsequently, the dispersion obtained in (Step 1) is mixed with other materials in (Step 2). In (Step 2), the mixing method is not particularly limited. In this manner, the target ink composition can be obtained.

[0060] [Uses] The ink composition of this embodiment is used to form components included in, for example, image display devices. Examples of such image display devices include display devices equipped with light-emitting elements such as OLED (organic light-emitting diode) elements, mini LEDs (mini light-emitting diodes), micro LEDs (micro light-emitting diodes), and quantum dots.

[0061] The ink composition of this embodiment is cured by exposure to light to form a cured product (cured film), which can function as a component within an image display device. Typically, this component is provided in a display area of ​​the image display device where an image is displayed. Here, the display area refers to an area of ​​the image display device that is defined by connecting the pixels that can be recognized by a person facing the image display device and the viewpoint of the person facing the image display device.

[0062] Typically, the ink composition is used to form partition walls provided in an image display device. Here, the partition walls are interposed between a plurality of light-emitting elements in an image display device including a plurality of light-emitting elements. In this case, the partition walls exert a function of controlling the direction of light emission when a certain light-emitting element emits light. As a result, the ink composition can contribute to improving the brightness of the image display device.

[0063] The reflectance characteristics of the cured product formed from the ink composition are preferably set, for example, as follows. That is, the average value of the diffuse reflectance of the cured product formed from the ink composition in the range of 400 nm to 700 nm is preferably 50% or more, more preferably 60% or more, and even more preferably 70% or more. By doing so, the function of controlling the direction of light emission as described above is more easily exhibited. Note that this diffuse reflectance can be measured using an ultraviolet-visible spectrophotometer (using an integrating sphere, SolidSpec-3700, manufactured by Shimadzu Corporation) or the like.

[0064] An example of an image display device provided with such partition walls will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an image display device in which a cured product of the ink composition according to this embodiment is used as a partition wall. The image display device 100 in FIG. 1 includes a substrate 10, partition walls 11, and light-emitting elements 12. The substrate 10 of this image display device 100 is made of a material selected from various materials, and may be made of either an inorganic material or an organic material. A typical example of the substrate 10 is a glass substrate, but it may also be made of a composite material made of glass fiber and epoxy resin, an organic material such as polyimide, or a ceramic other than glass. Although not shown in detail in the drawings, the substrate 10 typically includes circuits and electrodes so that a current can be applied to the light-emitting elements 12. The circuits and electrodes may be made of copper, indium tin oxide, or the like.

[0065] The light-emitting elements 12 are typically mini-LEDs or micro-LEDs, and the light-emitting elements 12(R), 12(G), and 12(B) emit light of different wavelengths (red, green, and blue). Note that the light-emitting elements 12 included in the image display device 100 of this embodiment may be OLEDs.

[0066] The partition walls 11 are formed by curing the ink composition of this embodiment, and are provided between the plurality of light-emitting elements 12. As described above, the partition walls 11 function to control the direction of light emission when the light-emitting elements 12 emit light. Note that, since the partition walls 11 of this embodiment are formed from a specific ink composition, they have excellent adhesion to the substrate 10, and can stably exhibit this function even during long-term use.

[0067] Such partition walls 11 can be obtained by applying an ink composition to a substrate 10 on which light-emitting elements 12 are mounted so that the ink composition is disposed between the light-emitting elements 12, and then photo-curing the ink composition. Such application is, for example, performed using an inkjet printer (i.e., the ink composition of this embodiment can also be said to be for inkjet use). While FIG. 1 shows a structure in which the partition walls 11 are disposed in positions so as to be in contact with the light-emitting elements 12 (the partition walls 11 are disposed so as to be in contact with at least one of the plurality of light-emitting elements 12), the partition walls 11 and the light-emitting elements 12 may also be configured to be spaced apart. In addition, when the partition walls 11 are disposed in positions so as to be in contact with the light-emitting elements 12, as in the image display device 100 shown in FIG. 1, this is preferable because it more easily performs the function of controlling the direction of light emission as described above.

[0068] In this embodiment, the height of the partition wall 11 and the light emitting element 12 (thickness in the thickness direction of the substrate 10) can be set appropriately. １１ ) and the average height of the plurality of light emitting elements 12 (average height H １２ ) is defined, H １１ and H １２ Specifically, H １１ and H １２ The ratio (H １１ / H １２ ) may be in the range of 0.6 to 1.5, may be in the range of 0.7 to 1.4, may be in the range of 0.8 to 1.2, or may be in the range of 0.9 to 1.1. By setting it in such a range, it becomes easier to control the direction of the light emitted by the light emitting element 12. On the other hand, from the viewpoint of simplifying the manufacturing process of the image display device 100, H １１ and H １２ The ratio of H to H may be different from the ranges stated above. １１ and H １２ The ratio (H １１ / H １２) may be in the range of 0.1 to 1.1, may be in the range of 0.2 to 1.0, may be in the range of 0.3 to 1.0, or may be in the range of 0.8 to 1.0. The average height of the partition walls 11 and the light-emitting elements 12 can be determined, for example, by disassembling the image display device 100 and observing the disassembled product with a scanning electron microscope or the like.

[0069] In the exemplary embodiment, the average height H of the partition wall 11 １１ may be 25 μm or less, or may be 20 μm or less. By doing so, it becomes easier to obtain a film quality that is uniform in the film thickness direction. Note that, from the viewpoint of suppressing interference of light emitted by the light emitting elements 12, the thickness of the partition walls 11 may be equal to or greater than the above-mentioned numerical value. In forming such partition walls 11, for example, the following method can be adopted. That is, the ink composition may be adjusted to a film thickness that allows it to be cured by exposure, and the ink composition may be once cured by exposure, and a coating film of the ink composition may be further formed on the cured film, thereby forming the partition walls 11 with a high film thickness (in other words, the partition walls 11 may be formed by laminating cured films of the ink composition). For this reason, the thickness of the partition walls 11 can be designed to be greater than the above-mentioned thickness as necessary. As an example, the average height H of the plurality of partition walls 11 may be set to 1 / 2 or more. １１ The thickness may be 300 μm or less, or may be 200 μm or less. From the viewpoint of improving the film quality of the partition walls 11, a heating step may be carried out after laminating the cured film to improve the degree of crosslinking of the film. １１ The lower limit of the thickness is not particularly limited, but is, for example, 1 μm or more.

[0070] On the other hand, the average height H of the light emitting element 12 １２ is set appropriately depending on the application and specifications of the image display device 100. As an example, the average height H １２ may be in the range of 1 to 100 μm, may be in the range of 2 to 80 μm, or may be in the range of 3 to 50 μm.

[0071] The hardness of the partition walls 11 may be adjusted for the purpose of improving the reliability of the resulting image display device 100. For example, the pencil hardness of the partition walls 11 may be H or more, 2H or more, 3H or more, or 4H or more.

[0072] The image display device to which the ink composition of this embodiment is applied may be as follows: Fig. 2 is a cross-sectional view of an image display device to which the cured product of the ink composition according to this embodiment is applied as a partition wall.

[0073] 2 includes a substrate 20, a partition wall 21, and a light-emitting element 22. The substrate 20 of this image display device 200 can be configured as the substrate 10 described above, and the light-emitting element 22 can be configured as the same as the light-emitting element 12 described above.

[0074] In the image display device 200, the partition wall 21 has a structure in which a plurality of layers (two layers) are laminated. Specifically, in the image display device 200 shown in Fig. 2, the partition wall 21 has a reflective material layer 21A and a light-shielding material layer 21B laminated thereon.

[0075] The reflective material layer 21A is formed by curing the ink composition of this embodiment and can be made of the same material as the partition wall 11 described above. On the other hand, the light-shielding material layer 21B can be made of a light-shielding material. This light-shielding material may contain either an inorganic material or an organic material. The light-shielding material layer 21B is provided between a plurality of light-emitting elements 22. In this case, the light-shielding material layer 21B functions to reduce light interference between a light-emitting element (e.g., light-emitting element 22(R)) and an adjacent light-emitting element (e.g., light-emitting element 22(G)) when the light-emitting element emits light, and to suppress display unevenness caused by reflection from wiring (metal wiring, etc.) formed on the substrate 20.

[0076] The reflective material layer 21A can be formed by applying a predetermined ink composition to the substrate 20 and curing it, similar to the partition wall 11 described above. On the other hand, when the light-shielding material layer 21B is configured to contain an inorganic material, it can be formed, for example, as follows. That is, the light-shielding material layer 21B can be formed by depositing an inorganic material having light-shielding properties (metals such as Al, Cu, Ti, Mo, and the like, or alloys thereof) on the reflective material layer 21A. On the other hand, when the light-shielding material layer 21B is configured to contain an organic material, it can be formed, for example, as follows. That is, the light-shielding material layer 21B can be formed by applying a mixed material of a light-shielding agent and a binder component to the reflective material layer 21A.

[0077] The light-blocking agent here may include carbon black or other light-blocking agents other than carbon black. Examples of these other light-blocking agents include inorganic light-blocking agents such as titanium black; iron oxide black; light-blocking agents containing one or more metal elements such as vanadium, silver, copper, and tin; organic black pigments such as aniline black, perylene black, and lactam black; and black dyes such as azo compounds and azine compounds. In addition, these other light-blocking agents may be formed by combining chromatic pigments such as red pigments, blue pigments, green pigments, and yellow pigments, or chromatic dyes such as red dyes, blue dyes, green dyes, and yellow dyes. These other light-blocking agents may be used alone or in combination as long as the light-blocking function of the resulting cured product is ensured.

[0078] On the other hand, the binder component may be either a plastic material or a curable material, but is typically a curable material. More specifically, the binder component may be a cured product of a polymerizable compound, and the polymerizable compound may be a radically polymerizable compound or a cationically polymerizable compound. In this case, the binder component may contain an agent that generates radicals or acids when exposed to light.

[0079] The height relationship between the partition wall 21 and the light-emitting element 22 may be the same as the height relationship between the partition wall 11 and the light-emitting element 12 in the image display device 100 shown in FIG. 1. The height ratio between the reflective material layer 21A and the light-shielding material layer 21B (height of the reflective material layer 21A:height of the light-shielding material layer 21B (H ２１Ａ : H ２１Ｂ On the other hand, from the viewpoint of achieving a good balance between improving the brightness of the light emitted by the image display device 200 and alleviating the interference of light between the light emitting elements, this H ２１Ａ : H ２１Ｂ may be in the range of 30:1 to 1:2, may be in the range of 20:1 to 1:1, may be in the range of 15:1 to 3:1.

[0080] Furthermore, the image display device to which the ink composition of this embodiment is applied may be as follows: Fig. 3 is a cross-sectional view of an image display device to which the cured product of the ink composition according to this embodiment is applied as partition walls.

[0081] 3 includes a substrate 30, a partition wall 31, and a light-emitting element 32. The substrate 30 of the image display device 300 can be configured similarly to the substrate 10 described above, and the partition wall 31 can be configured similarly to the partition wall 11 described above.

[0082] In the image display device 300, the plurality of light-emitting elements 32 are configured to emit light of the same color (see 32(B) in FIG. 3 ). In contrast, the image display device 300 of this embodiment is provided with a mechanism (wavelength adjustment layer) that adjusts the wavelength of light emitted by the light-emitting elements 32 on the substrate 30. Specifically, in the image display device 300 shown in FIG. 3 , a wavelength conversion layer (also referred to as wavelength conversion material 33) is provided on the side of the light-emitting element 32(B) opposite to the side on which the substrate 30 is located. Here, this wavelength conversion material 33 is provided with a wavelength conversion region 331, a wavelength conversion region 332, and a transparent region 333.

[0083] That is, in the image display device 300 shown in FIG. 3 , the wavelength conversion region 331 converts blue light emitted by the light-emitting element 32(B) into red light, while the wavelength conversion region 332 converts blue light emitted by the light-emitting element 32(B) into green light. These wavelength conversion regions 331 and 332 contain, for example, quantum dots, which can convert the wavelength of light received from the light-emitting element 32(B). By adopting such a configuration, RGB emission can be achieved as an image display device while achieving advantages in the manufacturing process, such as mounting the same type of light-emitting element on a substrate. While FIG. 3 shows a configuration in which blue light emitted by the light-emitting element 32(B) passes through the transparent region 333, the configuration of the image display device 300 is not necessarily limited to this. For example, a wavelength conversion region may be used instead of the transparent region 333. In this way, it is also possible to control (fine-tune) the color tone of the emitted blue light. 3 shows an embodiment in which the wavelength conversion material 33 including the wavelength conversion region 331 is employed, but a color filter may also be disposed on the light emitting element 32. Such a color filter filters out light of a certain wavelength region from the wavelength of the light emitted from the light emitting element 32. That is, in the image display device 300 of this embodiment, a layer may be provided as a wavelength adjustment layer that filters out light of a certain wavelength region from the light emitted by any of the plurality of light emitting elements. In this way, the color tone of the light emitted from the image display device 300 can be adjusted.

[0084] The partition walls of the various image display devices described above may have a structure different from that shown in the drawings. For example, a layer having another function may be interposed between the reflective material layer 21A and the light-shielding material layer 21B shown in FIG. 2. Furthermore, various partition walls may contain a component other than the material formed from the cured product of the ink composition of this embodiment. For example, the partition walls may contain another functional film (including a light-shielding film) extending in the height direction from the substrate. Furthermore, the image display device of this embodiment may have a configuration other than that shown in each drawing. For example, a separate cover glass or the like may be provided on the side of the light-emitting element or partition wall opposite the side where the substrate is present.

[0085] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0086] Furthermore, it may be provided in the following aspects.

[0087] (1) An ink composition comprising a reflective material (A), a cationically polymerizable compound (B), and a photoacid generator (C), wherein the cationically polymerizable compound (B) comprises a metal element-containing compound (B1) having a cationically polymerizable group and a hydrolyzable group.

[0088] (2) The ink composition according to (1) above, wherein the reflective material (A) contains a white pigment or a metallic pigment.

[0089] (3) In the ink composition according to (1) or (2) above, the Z-average particle size of the reflective material (A) is 100 nm or more and 1000 nm or less.

[0090] (4) The ink composition according to any one of (1) to (3) above, wherein the metal element-containing compound (B1) is a silicon-containing compound.

[0091] (5) The ink composition according to any one of (1) to (4) above, wherein the cationically polymerizable group of the metal element-containing compound (B1) is an epoxy group.

[0092] (6) The ink composition according to any one of (1) to (5) above, further comprising a sensitizer (D).

[0093] (7) In the ink composition according to any one of (1) to (6) above, the cationically polymerizable compound (B) further contains an oxetane compound as another cationically polymerizable compound (B2) that does not fall under the category of the metal element-containing compound (B1).

[0094] (8) In the ink composition according to any one of (1) to (7) above, the content of the metal element-containing compound (B1) is 1.5 parts by mass or more and 80 parts by mass or less, when the total solid content of the ink composition is 100 parts by mass.

[0095] (9) The ink composition according to any one of (1) to (8) above, which is an inkjet ink composition.

[0096] (10) The ink composition according to any one of (1) to (9) above, wherein the solid content is 70% by mass or more.

[0097] (11) The ink composition according to any one of (1) to (10) above, wherein the ink composition is used to form a partition wall in an image display device including a plurality of light-emitting elements, and the partition wall is interposed between the plurality of light-emitting elements.

[0098] (12) A cured product obtained by curing the ink composition according to any one of (1) to (11) above.

[0099] (13) An image display device comprising the cured product according to (12) above. Of course, the present invention is not limited to this.

[0100] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0101] [Raw Materials Used] First, the raw materials used in this example will be described. The raw materials used in this example are as follows. A1-1: Ti-Pure R-105 (rutile titanium oxide; manufactured by Chemours) A1-2: 49CJ-1120 (scale-shaped indium filler (solid content concentration 20%); manufactured by Oike Industries Co., Ltd.) B1-1: KBM-403 (chemical name: 3-glycidoxypropyltrimethoxysilane; manufactured by Shin-Etsu Chemical Co., Ltd.) B2-1: Aron Oxetane OXT-101 (chemical name: 3-ethyl-3-hydroxymethyl oxetane; manufactured by Toagosei Co., Ltd.) B2-2: Denacol EX-141 (chemical name: phenyl glycidyl ether; manufactured by Nagase ChemteX Corporation) B2-3: Aron Oxetane OXT-221 (chemical name: 3-ethyl-3{[3-ethyloxetan-3-yl]methoxy}methyl) oxetane; manufactured by Toagosei Co., Ltd.) B2-4: Denacol EX-121 (chemical name: 2-ethylhexyl glycidyl ether; manufactured by Nagase ChemteX Corporation) B2-5: Limonene dioxide (manufactured by RENESSENZ, LLC.) C1-1: CPI-110P (chemical name: diphenyl[4-(phenylthio)phenyl]sulfonium hexafluorophosphate; manufactured by San-Apro Ltd.) C1-2: CPI-110B (chemical name: diphenyl[4-(phenylthio)phenyl]sulfonium tetrakis(pentafluorophenyl)borate; manufactured by San-Apro Ltd.) D1-1: Anthracure (registered trademark) UVS-1331 (chemical name: 9,10-dibutoxyanthracene; manufactured by Air Water Performance Chemicals Inc.) D2-1: Omnirad DETX (chemical name: 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propane; manufactured by IGM ResinS) X-1: Solsperse 36000 (100% active polymer dispersant; manufactured by Lubrizol Japan Co., Ltd.) X-2: BYK-361N (polyacrylate surface conditioner; manufactured by BYK)

[0102] [Preparation of Ink Composition, etc.] A pigment dispersion and an ink composition were prepared according to the following steps.

[0103] (Preparation of Pigment Dispersion) Various materials were premixed to obtain the ratios shown in Table 1, and then processed in a sand mill for 5 hours to obtain a pigment dispersion containing a predetermined reflective material. In Example 8, a commercially available product in which an indium filler was dispersed was used as is.

[0104] (Preparation of Ink Composition) The pigment dispersion obtained above was thoroughly mixed with each of the components shown in Table 1 to prepare an ink composition. Table 1 also lists the solids concentration of the ink composition, the content (mass%) of component (A), the content (mass%) of component (B1), and the content (mass%) of the oxetane compound relative to the total solids. Ink compositions with a solids concentration of less than 100% contained propylene glycol monomethyl ether as a solvent.

[0105] [Evaluation] The ink compositions obtained were evaluated according to the following items. The evaluation results are shown in Table 1. The test environment was a temperature of 20°C and a humidity of 45%.

[0106] <Preparation of Evaluation Substrate> An inkjet printer (Stage JET, manufactured by Tritec Corporation) equipped with a piezoelectric inkjet head (KM1024iMHE, manufactured by Konica Minolta, Inc., ink droplet volume 13 pL) was prepared. Each ink composition was filled into this printer and ejected at a head temperature of 35°C. Eagle XG (Display Grade Glass, manufactured by Corning (registered trademark)) was used as the coated substrate. Next, the substrate was irradiated with UV light using a UV irradiation device (USHIO (Model) UVX-516, lamp: USHIO (Type) UVH-0501C-1200) until dry to the touch. The substrate was then heated for 10 minutes in a safe-type oven set at an internal temperature of 130°C to obtain an evaluation substrate.

[0107] The film thickness of the film formed from the ink composition and the cumulative dose of UV irradiation are as shown in Table 1. Here, the irradiation intensity and the cumulative dose were measured using a digital illuminometer (manufactured by Eye Graphics Co., Ltd., model: UVPF-A1, photoreceiver: PD-365).

[0108] In addition, in the case of one coating in Table 1, a cured film was obtained by inkjet coating followed by exposure and then heating. In the case of two coatings, inkjet coating was performed once, followed by exposure, and after this exposure, inkjet coating and exposure were performed again, and then heating was performed again.

[0109] <Diffuse reflectance measurement> Diffuse reflectance was measured in the 400 to 700 nm range using an ultraviolet-visible spectrophotometer (using an integrating sphere, manufactured by Shimadzu Corporation, SolidSpec-3700), and the average value was taken as the diffuse reflectance. Furthermore, diffuse reflectance was measured in the 450 to 470 nm range, and the average value was taken as the diffuse reflectance at 460 nm. Note that a Spectralon (registered trademark) reflection standard (model number: SRS-99-020) manufactured by Labsphere was used as the standard reflector.

[0110] <Transmittance Measurement> The transmittance in the range of 400 to 700 nm was measured using an ultraviolet-visible spectrophotometer (using an integrating sphere, manufactured by Shimadzu Corporation, SolidSpec-3700), and the average value was taken as the transmittance. Note that an unpainted Eagle XG was used for baseline measurement.

[0111] <Appearance> The appearance of the above evaluation substrates was evaluated according to the following evaluation criteria: A: No abnormalities B: Wrinkles occurred near the edges C: Wrinkles occurred over the entire coating film

[0112] <Adhesion> The above evaluation substrate was used as the adhesion evaluation substrate. For ink compositions that gave good results with Eagle XG, a glass epoxy substrate (Sunhayato's single-sided glass epoxy FR-4) and a Bakelite substrate (As One Corporation's Bakelite paper-containing phenolic resin) were also used as adhesion evaluation substrates. Specifically, adhesion evaluation substrates were prepared by coating and curing in the same manner as when Eagle XG was used. Adhesion was evaluated by a cross-cut test in accordance with JIS K5600-5-6:1999, with cuts made at 1 mm intervals, to evaluate the adhesion between the cured film and the substrate. A rating of 0 to 3 is within the practical range. 0: The edges of the cuts are completely smooth, and there is no peeling at any of the grid squares. 1: Minor peeling of the coating at the intersections of the cuts. The cross-cut area is not clearly affected by more than 5%. 2: The coating peels along the edges of the cuts and / or at the intersections. The cross-cut area is clearly more than 5% affected but not more than 15%. 3: The coating has partially or completely peeled off in large areas along the edges of the cuts and / or various areas of the mesh have partially or completely peeled off. The cross-cut area is clearly more than 15% affected but not more than 35% affected. 4: The coating has partially or completely peeled off in large areas along the edges of the cuts and / or several areas of the mesh have partially or completely peeled off. The cross-cut area is clearly not more than 65% affected. 5: Any level of peeling that cannot be classified as category 4.

[0113] <Pencil Hardness> The substrate on which the film was formed as described above was used as a substrate for pencil hardness evaluation. Using this evaluation substrate, pencil hardness evaluation was performed in accordance with the test method of JIS-K5600-5-4. The pencil used was a MITSU-BISHI pencil, and the test equipment used was a pencil scratch hardness tester manufactured by Toyo Seiki Seisakusho, Ltd.

[0114]

[0115] As can be seen from the results of this example, the ink composition of this embodiment can provide a cured product that has an excellent balance between substrate adhesion and reflectivity.

[0116] ​10, 20, 30: substrate, 11, 21, 31: partition wall, 12, 22, 32: light-emitting element, 21A: reflective material layer, 21B: light-shielding material layer, 22: light-emitting element, 33: wavelength conversion material, 100, 200, 300: image display device, 200: image display device, 300: image display device, 331: wavelength conversion region, 332: wavelength conversion region, 333: transparent region

Claims

1. An ink composition comprising: a reflective material (A); a cationically polymerizable compound (B); and a photoacid generator (C); wherein the cationically polymerizable compound (B) comprises a metal element-containing compound (B1) having a cationically polymerizable group and a hydrolyzable group.

2. The ink composition according to claim 1, wherein the reflective material (A) contains a white pigment or a metallic pigment.

3. The ink composition according to claim 1 or 2, wherein the Z-average particle size of the reflective material (A) is 100 nm or more and 1000 nm or less.

4. The ink composition according to any one of claims 1 to 3, wherein the metal element-containing compound (B1) is a silicon-containing compound.

5. The ink composition according to any one of claims 1 to 4, wherein the cationically polymerizable group of the metal element-containing compound (B1) is an epoxy group.

6. The ink composition according to any one of claims 1 to 5, further comprising a sensitizer (D).

7. An ink composition according to any one of claims 1 to 6, wherein the cationically polymerizable compound (B) further contains an oxetane compound as another cationically polymerizable compound (B2) not corresponding to the metal element-containing compound (B1).

8. The ink composition according to any one of claims 1 to 7, wherein the content of the metal element-containing compound (B1) is 1.5 parts by mass or more and 80 parts by mass or less when the total solid content of the ink composition is 100 parts by mass.

9. The ink composition according to any one of claims 1 to 8, which is for use in an inkjet printer.

10. The ink composition according to any one of claims 1 to 9, wherein the ink composition has a solid content of 70 mass % or more.

11. The ink composition according to any one of claims 1 to 10, which is used to form a partition wall, the partition wall being interposed between a plurality of light-emitting elements in an image display device having a plurality of light-emitting elements.

12. A cured product obtained by curing the ink composition according to any one of claims 1 to 11.

13. An image display device comprising the cured product according to claim 12.

Images