pigment dispersion

Abstract

To provide a pigment dispersion for coloring a resin composition for photolithography.SOLUTION: A dispersion according to the present invention is a dispersion for coloring a resin composition for photolithography, containing at least a pigment, a dispersant, and an organic solvent, the dispersant satisfying following conditions: (a) a combination of 1 mass% of indium tin oxide particles with an average primary particle size of 200 nm or less, 0.2 mass% of a dispersant, and the remainder being propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm, and the dispersion is measured by dynamic light scattering, resulting in the indium tin oxide particles having an average secondary particle size of 300 nm or more; and (b) a combination of 10 mass% of an organic pigment, 1.5 mass% of a dispersant, and the remainder being propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm, and the dispersion is measured by dynamic light scattering, resulting in the organic pigment having an average secondary particle size of less than 300 nm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention particularly relates to a pigment dispersion for coloring a resin composition for photolithography. [Background technology]

[0002] Conventionally, organic electroluminescent (organic EL) elements included in organic electroluminescent displays, organic electroluminescent lighting, etc. have been manufactured by forming partition walls (banks) on a substrate and then laminating various functional layers within the area surrounded by the partition walls. As a method for easily forming such partition walls, a photolithography method using a photosensitive resin composition is known.

[0003] Patent Document 1 discloses a photosensitive colored resin composition containing (A) a photopolymerization initiator, (B) an alkali-soluble resin, (C) a photopolymerizable compound, (D) a colorant, and (E) a liquid-repellent agent, wherein the (A) photopolymerization initiator has an absorbance at a wavelength of 400 nm that is greater than or equal to the maximum absorption wavelength (λ ) between 300 and 400 nm. max ) is 20% or more of the absorbance at a wavelength of 400 nm, and the absorbance at a maximum absorption wavelength (λ max ) is 10% or less of the absorbance at 1000 kJ / cm 3 / 2 ...

[0004] Patent Document 2 discloses a negative-type photosensitive resin composition containing (A) an alkali-soluble resin, (B) a radical-polymerizable compound, (C) a photopolymerization initiator, and (Da) a black pigment, wherein the (A) alkali-soluble resin contains one or more compounds selected from (A1-1) a polyimide, (A1-2) a polyimide precursor, (A1-3) a polybenzoxazole, and (A1-4) a polybenzoxazole precursor, the (C) photopolymerization initiator contains at least (C1) an oxime ester-based photopolymerization initiator and (C2) an α-hydroxyketone-based photopolymerization initiator, the content of the (C1) oxime ester-based photopolymerization initiator in the (C) photopolymerization initiator is 51 to 95 mass%, and the content of the (Da) black pigment is 5 to 50 mass% based on the total solid content of the negative-type photosensitive resin composition.

[0005] Patent Document 3 discloses a black pigment dispersion composition containing lactam black, a purple pigment, a blue pigment and / or a green pigment, and carbon black.

[0006] Patent Document 4 discloses a photosensitive coloring composition containing at least (A) a coloring material, (B) a dispersant, (C) an alkali-soluble resin, and (D) a photopolymerization initiator, wherein the (A) coloring material is (A-1) a compound represented by a given formula (1), a geometric isomer thereof, a salt thereof, or a salt of the geometric isomer thereof. The (A-2) organic coloring pigment is included, and the (A-1) organic black pigment is contained in an amount of 30 to 90% by mass relative to 100% by mass of the (A) coloring material. The (A) coloring material is contained in an amount of 20% by mass or more relative to the total solid content in the photosensitive coloring composition. The (B) dispersant is a polymer dispersant having a quaternary ammonium base as a functional group.

[0007] Patent Document 5 discloses a photosensitive coloring composition containing (a) a colorant, (b) an alkali-soluble resin, (c) a photopolymerization initiator, (d) an ethylenically unsaturated compound, (e) a solvent, and (f) a dispersant, wherein the (a) colorant contains an organic black pigment that is a compound represented by a given formula, a geometric isomer thereof, a salt thereof, or a salt of the geometric isomer, and the (c) photopolymerization initiator contains an oxime ester compound having a diphenyl sulfide skeleton represented by another given formula.

[0008] Patent Document 6 discloses a colorant dispersion containing a colorant (E), wherein the colorant (E) contains a pigment (E1) and a dispersant (E2), and the dispersant (E2) contains a silsesquioxane compound having a structural unit represented by a given formula. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2020 / 017576 [Patent Document 2] International Publication No. 2019 / 150938 [Patent Document 3] Japanese Patent Application Publication No. 2019-81857 [Patent Document 4] Patent No. 6489008 [Patent Document 5] Patent No. 6528475 [Patent Document 6] Japanese Patent Application Publication No. 2018-70695 Summary of the Invention [Problem to be solved by the invention]

[0010] Generally, a transparent resin such as polyimide is used as the photosensitive resin in a resin composition for photolithography. Therefore, the resin composition for photolithography contains a colorant to prevent the electrical wiring from being visible through the bank, to prevent reflection, and / or to improve contrast.

[0011] Therefore, the present invention provides a pigment dispersion for coloring a resin composition for photolithography. [Means for solving the problem]

[0012] The present inventors have conducted extensive research and found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows: <Aspect 1> A dispersion for coloring a resin composition for photolithography, comprising at least an organic pigment, a dispersant, and an organic solvent, wherein the dispersant satisfies the following conditions (a) and (b): (a) When a mixture of 1% by mass of indium tin oxide having an average primary particle size of 200 nm or less, 0.2% by mass of the dispersant, and the remainder being propylene glycol monomethyl ether is dispersed using zirconia beads having a particle size of 0.3 mm and measured by a dynamic light scattering method, the average secondary particle size of the indium tin oxide particles is 300 nm or more, and (b) When a blend of 10% by mass of the organic pigment, 1.5% by mass of a dispersant, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm and measured by dynamic light scattering, the average secondary particle size of the organic pigment is less than 300 nm. Aspect 2: The dispersion of aspect 1, wherein the indium tin oxide satisfies the following: When a mixture of 1 mass % of indium tin oxide, 0.2 mass % of a dispersant suitable for dispersing indium tin oxide, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm and measured by dynamic light scattering, the average secondary particle size of the indium tin oxide particles is 200 nm or less. Aspect 3: The dispersion liquid according to aspect 1 or 2, wherein the organic pigment is a benzofuranone-based pigment. <Aspect 4> The dispersion according to any one of Aspects 1 to 3, wherein the dispersant is at least one selected from the group consisting of polyester-based dispersants, polyurethane-based dispersants, and polyacrylic-based dispersants. <Aspect 5> The dispersion according to any one of Aspects 1 to 4, wherein the organic solvent is at least one selected from the group consisting of glycol ethers and esters. Aspect 6: A resin composition for photolithography, comprising the pigment dispersion according to any one of Aspects 1 to 5, and a photosensitive resin. [Effects of the Invention]

[0013] According to the present invention, a pigment dispersion for coloring a resin composition for photolithography can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0014] 《Dispersion liquid》 The dispersion of the present invention is a dispersion for coloring a resin composition for photolithography, which contains at least a pigment, a dispersant, and an organic solvent, and the dispersant satisfies the following conditions (a) and (b): (a) When a mixture of 1 mass % indium tin oxide particles having an average primary particle size of 200 nm or less, 0.2 mass % of the dispersant, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads having a particle size of 0.3 mm and measured by a dynamic light scattering method, the average secondary particle size of the indium tin oxide particles is 300 nm or more, and (b) When a blend of 10% by mass of the organic pigment, 1.5% by mass of a dispersant, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm and measured by dynamic light scattering, the average secondary particle size of the organic pigment is less than 300 nm.

[0015] The present inventors have found that when unnecessary portions of a resin composition for photolithography are removed to prepare a bank, components of the resin composition for photolithography, such as a dispersant and / or a pigment, may remain on the substrate, particularly on the electrode surface of the substrate, which may have an undesirable effect on the resulting organic EL device.

[0016] In response to this, the present inventors have discovered that by incorporating a specific dispersant into a resin composition for photolithography, it is possible to prevent components of the resin composition for photolithography from remaining on the substrate during bank production.

[0017] Each component of the present invention will be described below.

[0018] Pigments Examples of the pigment that can be used include carbon-based pigments such as amorphous carbon powder, graphene, carbon nanotubes, graphite, and carbon black. Examples of the pigment that can be used include organic pigments such as benzofuranone pigments, azo pigments, condensed azo pigments, phthalocyanine pigments, anthraquinone pigments, quinacridone pigments, isoindolinone pigments, diketopyrrolopyrrole pigments, and various lake pigments.

[0019] As the pigment, it is preferable to use a black pigment from the viewpoint of hiding power.

[0020] The average particle size of the pigment may be 50 nm or more, 70 nm or more, 80 nm or more, 100 nm or more, 120 nm or more, 150 nm or more, 170 nm or more, 200 nm or more, 220 nm or more, 250 nm or more, 270 nm or more, or 300 nm or more, and may be 1000 nm or less, 800 nm or less, 700 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, or 400 nm or less.

[0021] In this specification, the average secondary particle diameter is the average particle diameter measured using dynamic light scattering. Specifically, this average secondary particle diameter is the average particle diameter value measured using the cumulant method analysis of the scattering intensity distribution, calculated using a concentrated particle analyzer FPAR-1000 (Otsuka Electronics Co., Ltd.).

[0022] The pigment content in the pigment dispersion may be 5% by mass or more, 10% by mass or more, or 12% by mass or more, and may be 30% by mass or less, 25% by mass or less, 20% by mass or less, or 15% by mass or less, based on the mass of the pigment dispersion.

[0023] <Dispersant> The dispersant is a dispersant that satisfies the following conditions (a) and (b): (a) When a blend of 1 mass % indium tin oxide particles having an average primary particle size of 200 nm or less, particularly an average primary particle size of 150 nm or less, 0.2 mass % of the dispersant, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads having a particle size of 0.3 mm and measured by a dynamic light scattering method, the average secondary particle size of the indium tin oxide particles is 300 nm or more, and (b) When a blend of 10% by mass of the organic pigment, 1.5% by mass of a dispersant, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm and measured by dynamic light scattering, the average secondary particle size of the organic pigment is less than 300 nm.

[0024] Here, the indium tin oxide used in (a) above may satisfy the following: When a mixture of 1% by mass of indium tin oxide, 0.2% by mass of a dispersant suitable for dispersing indium tin oxide, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm and measured by dynamic light scattering, the average secondary particle size of the indium tin oxide particles is 200 nm or less, particularly 150 nm or less. For example, ITO-R (CIK Nanotech Co., Ltd.) can be used as the indium tin oxide particles.

[0025] Examples of dispersants suitable for dispersing indium tin oxide include: DISPERBYK-167 (BYK Additives & Instruments), Ajisper PB-881 (Ajinomoto Fine-Techno Co., Ltd.), DISPERBYK-2200 (BYK Additives & Instruments), DISPERBYK-2155 (BYK Additives & Instruments), EFKA (registered trademark) PX4701 (BASF), Solsperse 76500 (Lubrizol), Disparlon (registered trademark) SPD-202SS (Kusumoto Chemicals Co., Ltd.), Disparlon (registered trademark) DA 7301 (Kusumoto Chemicals Co., Ltd.), Flourene DOPA-17HF (Kyoeisha Chemical Co., Ltd.), Borchi (registered trademark) gen 1051 (Borcher), TEGO® DISPERS 670 (Evonik).

[0026] The average secondary particle size of the indium tin oxide particles measured by dynamic light scattering may be more than 1.0 times, 1.2 times or more, 1.5 times or more, 2.0 times or more, 2.5 times or more, or 3.0 times or more of the average secondary particle size of the organic pigment measured by dynamic light scattering, and may be 20.0 times or less, 18.0 times or less, 16.0 times or less, 14.0 times or less, 12.0 times or less, 10.0 times or less, 9.0 times or less, 8.0 times or less, 7.0 times or less, or 6.0 times or less.

[0027] The dispersant used in the present invention has a low ability to disperse indium tin oxide particles and a good dispersibility for the pigment used in the dispersion liquid. It has been found that such a dispersant can effectively disperse the pigment while suppressing adhesion of the dispersant to the indium tin oxide layer of the substrate, thereby improving the properties of the resulting organic EL device.

[0028] Examples of such dispersants include polyester dispersants, polyurethane dispersants, and polyacrylic dispersants. Specific examples of such dispersants include the following: Ajisper PB-821 (Ajinomoto Fine-Techno Co., Ltd.) Solsperse 20000 (Lubrizol) Solsperse 16000 (Lubrizol) Ethreem AD 508E (NOF Corporation) Esreem AD 374M (NOF Corporation).

[0029] The content of the dispersant in the pigment dispersion may be 0.25% by mass or more, 0.5% by mass or more, 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, or 9% by mass or more, based on the solids mass of the dispersion, and may be 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less.

[0030] The content of the dispersant may be 5 parts by mass or more, 10 parts by mass or more, 15 parts by mass or more, 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 45 parts by mass or more, 50 parts by mass or more, 55 parts by mass or more, 60 parts by mass or more, or 65 parts by mass or more, relative to 100 parts by mass of the pigment, and may be 100 parts by mass or less, 90 parts by mass or less, 85 parts by mass or less, 80 parts by mass or less, 75 parts by mass or less, or 70 parts by mass or less.

[0031] <Organic solvent> Examples of the organic solvent that can be used include aromatics, alcohols, polyhydric alcohols, glycol ethers, hydrocarbons, esters, etc. These solvents may be used alone or in combination.

[0032] Examples of aromatic compounds that can be used include benzyl alcohol, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, propylene glycol monophenyl ether, diethylene glycol monophenyl ether, alkylsulfonic acid phenyl ester, butyl phthalate, ethylhexyl phthalate, tridecyl phthalate, ethylhexyl trimellitate, diethylene glycol dibenzoate, and dipropylene glycol dibenzoate.

[0033] Examples of alcohols that can be used include ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butyl alcohol, 1-pentanol, isoamyl alcohol, sec-amyl alcohol, 3-pentanol, tert-amyl alcohol, n-hexanol, methylamyl alcohol, 2-ethylbutanol, n-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-octanol, 2-ethylhexanol, 3,5,5-trimethylhexanol, nonanol, n-decanol, undecanol, n-decanol, trimethylnonyl alcohol, tetradecanol, heptadecanol, cyclohexanol, and 2-methylcyclohexanol.

[0034] Examples of polyhydric alcohols that can be used include ethylene glycol, diethylene glycol, 3-methyl-1,3 butanediol, triethylene glycol, dipropylene glycol, 1,3 propanediol, 1,3 butanediol, 1,5 pentanediol, hexylene glycol, and octylene glycol.

[0035] Examples of glycol ethers that can be used include methyl isopropyl ether, ethyl ether, ethyl propyl ether, ethyl butyl ether, isopropyl ether, butyl ether, hexyl ether, 2-ethylhexyl ether, ethylene glycol monohexyl ether, ethylene glycol mono-2-ethylbutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, 3-methyl-3-methoxy-1-butanol, 3-methoxy-1-butanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol tertiary butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, and tetrapropylene glycol monobutyl ether.

[0036] As the hydrocarbons, for example, straight-chain hydrocarbons such as hexane, isohexane, heptane, octane, nonane, and decane, and cyclic hydrocarbons such as cyclohexane, methylcyclohexane, and ethylcyclohexane can be used.

[0037] Examples of esters include propylene glycol methyl ether acetate, propylene glycol diacetate, 3-methyl-3-methoxybutyl acetate, propylene glycol ethyl ether acetate, ethylene glycol ethyl ether acetate, butyl formate, isobutyl formate, isoamyl formate, propyl acetate, butyl acetate, isopropyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, propyl propionate, isobutyl propionate, isoamyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, propyl isobutyrate, Examples of usable surfactants include methyl valerate, ethyl valerate, propyl valerate, methyl isovalerate, ethyl isovalerate, propyl isovalerate, methyl trimethylacetate, ethyl trimethylacetate, propyl trimethylacetate, methyl caproate, ethyl caproate, propyl caproate, methyl caprylate, ethyl caprylate, propyl caprylate, methyl laurate, ethyl laurate, methyl oleate, ethyl oleate, caprylic acid triglyceride, tributyl acetate citrate, octyl oxystearate, propylene glycol monoricinoleate, methyl 2-hydroxyisobutyrate, and 3-methoxybutyl acetate.

[0038] <<Resin Composition for Photolithography>> The resin composition for photolithography of the present invention contains the above-mentioned pigment dispersion and a photosensitive resin.

[0039] A bank using this resin composition can be produced by, for example, negative or positive photolithography.

[0040] More specifically, in the case of negative photolithography, the resin composition is applied to a substrate for an organic EL element, for example, a substrate having an indium tin oxide (ITO) layer, to form a resin layer, and then the resin layer is exposed to light in areas corresponding to the banks, and then the resin layer is washed to remove (develop) the unexposed areas, thereby producing a bank.

[0041] In the case of positive photolithography, the resin composition is applied to a substrate for an organic EL element to form a resin layer, and then the resin layer is exposed to light in areas other than those corresponding to the bank, and the resin layer is then washed to remove (develop) the exposed areas, thereby producing a bank.

[0042] The content of the pigment in the resin composition for photolithography may be 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, or 4% by mass or more, based on the mass of the resin composition for photolithography, and may be 15% by mass or less, 13% by mass or less, 11% by mass or less, 9% by mass or less, 7% by mass or less, 6% by mass or less, or 5% by mass or less.

[0043] The content of the dispersant in the resin composition for photolithography may be, based on the mass of the resin composition for photolithography, 0.025 mass% or more, 0.05 mass% or more, 0.1 mass% or more, 0.3 mass% or more, 0.5 mass% or more, 0.7 mass% or more, 1 mass% or more, 2 mass% or more, or 3 mass% or more, or 15 mass% or less, 13 mass% or less, 11 mass% or less, 9 mass% or less, 7 mass% or less, 5 mass% or less, or 4 mass% or less. Furthermore, the content of the dispersant in the resin composition for photolithography may be such that the ratio of the dispersant to the pigment is the ratio shown for the dispersion.

[0044] <Photosensitive resin> As the photosensitive resin, for example, a negative photosensitive resin or a positive photosensitive resin can be used.

[0045] As taught in Patent Document 2, for example, a resin composition containing an alkali-soluble resin, a radical polymerizable compound, and a photopolymerization initiator can be used as the negative photosensitive resin.

[0046] Examples of alkali-soluble resins that can be used include polyimides, polyimide precursors, polybenzoxazoles, and polybenzoxazole precursors.

[0047] Examples of the radical polymerizable compound include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, 1,3-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol nona(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, pentaerythritol undeca(meth)acrylate, pentaerythritol dodeca(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, 2,2-bis[4-(3-(meth)acryloxy-2-hydroxypropoxy)phenyl]propane, 1,3,5-tris((meth)acryloxyethyl)isocyanuric acid, 1,3-bis((meth)acryloxyethyl)isocyanuric acid, or acid-modified products thereof can be used.

[0048] The photopolymerization initiator may be, for example, a photopolymerization initiator containing at least an oxime ester-based photopolymerization initiator and an α-hydroxyketone-based photopolymerization initiator.

[0049] The content of the photosensitive resin may be 20% by mass or more, 25% by mass or more, 30% by mass or more, 35% by mass or more, 40% by mass or more, 45% by mass or more, 50% by mass or more, 55% by mass or more, 60% by mass or more, 65% by mass or more, or 70% by mass or more, based on the total mass of the resin composition for photolithography, and may be 95% by mass or less, 90% by mass or less, 85% by mass or less, 80% by mass or less, or 75% by mass or less. [Example]

[0050] The present invention will be specifically explained with reference to examples and comparative examples, but the present invention is not limited to these.

[0051] <<Evaluation of Dispersants>> <Evaluation of Dispersibility of Indium Tin Oxide> A dispersion was prepared containing 1 mass % indium tin oxide particles (CIK Nanotech), 0.2 mass % of a dispersant shown in Table 1, and the remainder being propylene glycol monomethyl ether. The indium tin oxide particles in this dispersion were dispersed using zirconia beads with a particle size of 0.3 mm, and then the average particle size of the indium tin oxide particles was measured by dynamic light scattering.

[0052] <Evaluation of dispersibility of organic pigments> A dispersion was prepared containing 10 mass% of an organic pigment (Irgaphor Black S0100CF, BASF), 0.2 mass% of a dispersant shown in Table 1, and the remainder being propylene glycol monomethyl ether. The organic pigment in this dispersion was dispersed using zirconia beads with a particle size of 0.3 mm, and then the average particle size of the organic pigment was measured by dynamic light scattering.

[0053] Details of the organic pigments used are as follows: IRGAPHOR BLACK S0100CF (benzofuranone-based black pigment with primary particles of 40-80 nm)

[0054] Details of each dispersant and the evaluation results are shown in Table 1.

[0055] [Table 1]

[0056] As shown in Table 1, dispersants in which the average secondary particle diameter of dispersed indium tin oxide particles is 300 nm or more and the average secondary particle diameter of dispersed organic pigment is less than 300 nm are considered to be dispersants of Examples, and dispersants that do not satisfy these conditions are considered to be dispersants of Comparative Examples. Note that when the dispersant of Comparative Example 10 was used, the average secondary particle diameter of dispersed indium tin oxide particles was 147 nm, which is clear, so the average primary particle diameter of the indium tin oxide particles used in the evaluation was 200 nm or less, particularly 150 nm or less.

[0057] <<Preparation of pigment dispersions, coating films, and organic EL devices>> The pigment dispersion of Example 2 was prepared by mixing 4.13 parts by mass of a pigment (Irgaphor (registered trademark) Black S0100CF, BASF), 1.24 parts by mass of the dispersant of Example 2, and 22.14 parts by mass of propylene glycol monomethyl ether.

[0058] Next, 2.75 parts by mass of the prepared pigment dispersion was mixed with 7.25 parts by mass of a photosensitive resin (DL-1000, Toray Industries, Inc.) to prepare a resin composition for photolithography.

[0059] The prepared resin composition was applied to a substrate having an indium tin oxide (ITO) layer to form a resin layer, and then the resin layer was exposed to light with an energy of 500 mJ at the locations corresponding to the positions of the banks.The resin layer was then washed with tetramethylammonium hydroxide as a developer to remove (develop) the resin layer in the areas other than the banks, thereby producing banks with a thickness of 1.2 μm.

[0060] Next, an organic EL device for evaluation was fabricated in the same manner as in Patent Document 2.

[0061] Specifically, a nitrogen plasma treatment was performed as a pretreatment on an ITO substrate serving as an anode on which a bank had been formed, and then a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport material, and a cathode were deposited in this order by vacuum deposition. The specific materials used for the hole injection layer, the hole transport layer, the light-emitting layer, the electron transport material, and the cathode were the same as those used in Patent Document 2.

[0062] A pigment dispersion, a coating film, and an organic EL device of Comparative Example 1 were prepared in the same manner as in Example 2, except that the dispersant of Comparative Example 1 was used instead of the dispersant of Example 2.

[0063] <Evaluation of organic EL display devices> <Light Emitting Characteristics 1> The organic EL device prepared by the above method was stored at 85°C for 192 hours, and then luminescence was caused by applying a voltage of 3.5V. The device was then observed under a microscope to check for luminescence defects such as non-luminescent areas or uneven brightness (microscope body: ECLIPSE, model LV150, Nikon Corporation; microscope objective lens: LU Plan Fluor 5x, Nikon Corporation). Luminescent areas with varying brightness were considered to have uneven brightness, and areas with uneven brightness were considered to have no light emission. The evaluation criteria were as follows: A: The light is emitted uniformly, with no uneven brightness. B: Light is emitted, but there is some unevenness in brightness. C: The light emission is weak and there is uneven brightness. D: Not emitting light.

[0064] <Light Emitting Characteristics 2> The organic EL device fabricated by the above method was made to emit light at an applied voltage of 5 V, and the light-emitting characteristics were evaluated based on changes in current.

[0065] As an index of the light-emitting properties, the change in current compared with an organic EL element fabricated using an uncolored (transparent) resin composition for photolithography (DL-1000, Toray Industries, Inc.), i.e., a resin composition for photolithography that does not contain a pigment (referred to as "Comparative Example 12" in Table 2), was calculated using the following formula. Current change = Yb / Yc Yb: Current density when using a photolithography resin composition containing a pigment dispersion Yc: Current density when using uncolored (transparent) photolithography resin composition (DL-1000)

[0066] The current density was measured at 5.0 V using an automatic IVL characteristic measuring device (ETS-170, System Giken Co., Ltd.).

[0067] The evaluation criteria are as follows: A: 0.90 or higher B: 0.80 or more and less than 0.90 C: 0.60 or more and less than 0.80 D: Less than 0.60

[0068] Table 2 shows the configurations and evaluation results of the examples and comparative examples.

[0069] [Table 2]

Claims

1. A dispersion for coloring a resin composition for photolithography, comprising at least a benzofuranone pigment, a dispersant, and an organic solvent containing glycol ethers, wherein the dispersant satisfies the following conditions (a) and (b): (a) When a mixture of 1 mass % indium tin oxide particles having an average primary particle size of 200 nm or less, 0.2 mass % of the dispersant, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads having a particle size of 0.3 mm and measured by a dynamic light scattering method, the average secondary particle size of the indium tin oxide particles is 300 nm or more, and (b) In a formulation containing 10% by mass of the organic pigment, 1.5% by mass of a dispersant, and the remainder being propylene glycol monomethyl ether, the dispersion is dispersed using zirconia beads having a particle size of 0.3 mm, and when the dispersion is measured by a dynamic light scattering method, the average secondary particle size of the organic pigment is less than 300 nm.

2. 10. The dispersion of claim 1, wherein the indium tin oxide satisfies: When a mixture of 1 mass % of indium tin oxide, 0.2 mass % of a dispersant suitable for dispersing indium tin oxide, and the remainder propylene glycol monomethyl ether is dispersed using zirconia beads with a particle size of 0.3 mm and measured by dynamic light scattering, the average secondary particle size of the indium tin oxide particles is 200 nm or less.

3. 3. The dispersion according to claim 1, wherein the dispersant is at least one selected from the group consisting of polyester-based dispersants, polyurethane-based dispersants, and polyacrylic-based dispersants.

4. The dispersion according to any one of claims 1 to 3, wherein the organic solvent is a combination of propylene glycol monomethyl ether and an ester.

5. A resin composition for photolithography, comprising the pigment dispersion according to any one of claims 1 to 4 and a photosensitive resin.

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