Composition for forming wavelength conversion film for display

Abstract

Provided is a composition for forming a wavelength conversion film for a display which yields a wavelength conversion film having excellent wavelength conversion efficiency and has excellent storage stability. The composition for forming a wavelength conversion film for a display includes (A) a phosphor, (B) titanium oxide particles, and (C) a binder. The (B) titanium oxide particles may be coated on the surface thereof with an inorganic compound. The (B) titanium oxide particles have an average particle size greater than 50 nm and less than 200 nm and a viscosity of 10,000 mPa · s or less at 25ºC.

Description

Technical Field

[0001] The present invention relates to a composition for forming a wavelength conversion film for a display, and more specifically, to a composition for forming a wavelength conversion film for a display that is suitably used for various displays such as liquid crystal displays, organic EL displays, and micro LED displays.

Background Art

[0002] Micro LED displays are expected to be the next-generation displays after liquid crystal displays and organic EL displays because they can achieve high contrast and high brightness, and also have a wide range of applications such as large-screen displays and transparent displays. In a micro LED display, usually, micro LED chips are arranged in each pixel. As a method of arranging these LED chips, there is an RGB-LED method in which three-color LEDs are mounted. However, in this method, the complexity of light emission control of the LEDs and the low performance of red LEDs are problems, and a wavelength conversion method that can solve these problems has attracted attention. In the wavelength conversion method, only blue LED chips are used, and red and green light are extracted by a wavelength conversion material. It has the advantage that the three primary colors can be created using only blue LED chips.

[0003] Conventionally, technologies using organic light-emitting materials as wavelength conversion materials have been proposed. For example, those using a pyridine-phthalimide condensate (Patent Document 1, etc.), those using a coumarin derivative (Patent Document 2, etc.), those using a perylene derivative (Patent Document 3, etc.), those using a rhodamine derivative (Patent Document 4), and those using a pyromethene derivative (Patent Documents 5, 6, etc.) have been disclosed.

[0004] These wavelength conversion materials are generally required to have characteristics such as good wavelength conversion efficiency, color purity, and light resistance. In this regard, for example, Patent Document 7 discloses that a composition containing a binder resin made of a specific methacrylic polymer, a specific fluorescent dye, and a photopolymerizable acrylate ester can be a high-performance red conversion material with good light resistance. Also, techniques for adding a light stabilizer to prevent deterioration of the organic light-emitting material and improve durability have been disclosed (Patent Document 8, etc.). Furthermore, it is known that by adding fine particles to the wavelength conversion material, the optical path length is increased due to light scattering in the color conversion layer, improving the blue light absorption rate, and the light reflected at the interface is scattered again, improving the light emission efficiency (Patent Documents 9, 10, etc.).

[0005] However, with the recent development of display technology, for the composition for forming a wavelength conversion film for displays, from the viewpoint of improving the performance of the display, further improvement in the wavelength conversion efficiency of the wavelength conversion material is required, and from the viewpoint of productivity, further improvement in the storage stability of the composition is required.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Patent Document 9

Patent Document 10

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a wavelength conversion film excellent in wavelength conversion efficiency and a composition for forming a wavelength conversion film for a display excellent in storage stability.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that a composition for forming a wavelength conversion film for a display containing titanium oxide particles having an average particle diameter in a specific range and having a viscosity adjusted to a specific range can solve the above problems, and completed the present invention.

[0009] That is, the present invention provides the following composition for forming a wavelength conversion film for a display. 1. A composition for forming a wavelength conversion film for a display, containing (A) a phosphor, (B) titanium oxide particles, and (C) a binder, wherein the surface of the above (B) titanium oxide particles may be coated with an inorganic compound, and the average particle diameter thereof is more than 50 nm and less than 200 nm, and the viscosity at 25°C is 10,000 mPa·s or less. 2. The composition for forming a wavelength conversion film for a display according to 1, wherein the average particle diameter of the above (B) titanium oxide particles is 60 to 190 nm. 3. The composition for forming a wavelength conversion film for a display according to 1 or 2, wherein the above (B) titanium oxide particles are particles whose surfaces are not coated. 4. The composition for forming a wavelength conversion film for a display according to any one of 1 to 3, wherein the content of the above (B) titanium oxide particles is 3 to 10% by mass in the solid content. 5. The composition for forming a wavelength conversion film for a display according to any one of 1 to 4, wherein the above (A) phosphor is an organic dye. 6. A composition for forming a wavelength conversion film for a display, wherein the haze value of the film formed from the composition is 18% or more, and the composition is any one of 1 to 5.

Advantages of the Invention

[0010] According to the present invention, it is possible to provide a composition for forming a wavelength conversion film for a display that gives a wavelength conversion film excellent in wavelength conversion efficiency and also excellent in storage stability.

Modes for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described in more detail. The composition for forming a wavelength conversion film for a display of the present invention contains (A) a phosphor, (B) titanium oxide particles, and (C) a binder. The surface of the above (B) titanium oxide particles may be coated with an inorganic compound, the average particle diameter thereof is more than 50 nm and less than 200 nm, and the viscosity at 25 ° C is 10,000 mPa·s or less. When the surface of the (B) titanium oxide particles is coated with an inorganic compound, the average particle diameter is the average particle diameter of the titanium oxide particles coated with the inorganic compound. In the following description, the solid content means components other than the solvent constituting the composition for forming a wavelength conversion film for a display.

[0012] The above (A) phosphor can be appropriately selected from conventionally known inorganic phosphors, organic dyes, semiconductor nanoparticles (quantum dots, quantum rods, etc.). From the viewpoints of high definition of the display and storage stability of the composition, an organic dye is preferable. In the present invention, it is preferably free of semiconductor nanoparticles.

[0013] Examples of the organic dyes include compounds having a condensed aryl ring such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, indene, and derivatives thereof; compounds having a heteroaryl ring such as furan, pyrrole, thiophene, silole, 9-silafluorene, 9,9'-spirobisilafluorene, benzothiophene, benzofuran, indole, dibenzothiophene, dibenzofuran, imidazopyridine, phenanthroline, pyridine, pyrazine, naphthyridine, quinoxaline, pyrrolopyridine, and derivatives thereof; stilbene derivatives such as 1,4-distyrylbenzene, 4,4'-bis(2-(4-diphenylaminophenyl)ethenyl)biphenyl, 4,4'-bis(N-(stilben-4-yl)-N-phenylamino)stilbene; aromatic acetylene derivatives; tetraphenylbutadiene derivatives; aldazine derivatives; pyromethene derivatives; diketopyrrolo[3,4-c]pyrrole derivatives; coumarin derivatives such as coumarin 6, coumarin 7, coumarin 153, and the compounds disclosed in Patent Document 7; naphthophosphole oxide derivatives; azole derivatives such as imidazole, thiazole, thiadiazole, carbazole, oxazole, oxadiazole, triazole, and metal complexes thereof; cyanine compounds such as indocyanine green; xanthene compounds and thioxanthene compounds such as fluorescein, eosin, rhodamine; polyphenylene compounds, naphthalimide derivatives, phthalocyanine derivatives and metal complexes thereof, porphyrin derivatives and metal complexes thereof; oxazine compounds such as Nile red and Nile blue; helicene compounds; aromatic amine derivatives such as N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diphenyl-1,1'-diamine; organometallic complex compounds such as iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium (Pd), platinum (Pt), osmium (Os), rhenium (Re), etc., but are not limited thereto. In the present invention, the organic dye does not include a dye (B1) having a partial structure represented by the general formula [1] disclosed in JP-A-2021-128338.

[0014] Among the above organic dyes, coumarin derivatives, naphthophosphole oxide derivatives, pyromethene derivatives, and perylene derivatives are preferred in the present invention.

[0015] As the above coumarin derivative, a coumarin derivative represented by the following formula (1) is preferred.

[0016]

Chemical formula

[0017] In formula (1), R 1 and R 2 each independently represent an alkyl group having 2 to 10 carbon atoms, and R 3 and R 4 each independently represent an alkyl group having 2 to 8 carbon atoms, provided that R 3 and R 4 may be bonded to each other to form a ring together with a nitrogen atom. The above alkyl group having 2 to 10 carbon atoms may be linear, branched, or cyclic. Specific examples thereof include ethyl, n-propyl, i-propyl, n-butyl, n-hexyl, n-octyl, 2-ethylhexyl, cyclohexylmethyl, and neopentyl groups. The above alkyl group having 2 to 8 carbon atoms may be linear, branched, or cyclic. Specific examples thereof include those having 2 to 8 carbon atoms among the above alkyl groups having 2 to 10 carbon atoms.

[0018] Among these, it is preferable that one of R 1 and R 2 is a linear alkyl group and the other is a branched or cyclic alkyl group, and a combination of an n-hexyl group and a cyclohexylmethyl group is more preferable. R 3 and R 4 are preferably ethyl, n-propyl, n-butyl, n-hexyl, n-octyl, 2-ethylhexyl groups, and more preferably n-butyl group and n-hexyl group. Preferable examples of the coumarin derivative represented by formula (1) include, but are not limited to, the compound represented by the following formula (1A).

[0019]

Chemical formula

[0020] The coumarin derivative represented by the above formula (1A) can be synthesized, for example, using known reactions as shown in the following scheme.

[0021]

Chemical formula

[0022] That is, in the first step, according to the reaction described in paragraph

[0037] of Chinese Patent Publication No. 105001666A, etc., m-aminophenol is reacted with cyclohexylmethane halides such as bromocyclohexylmethane and 1-halohexanes such as 1-bromohexane in the presence of a base in a solvent to synthesize compound A-1. In this reaction, the usage amounts of cyclohexylmethane halide and 1-halohexane are each preferably about 0.5 mol with respect to 1 mol of m-aminophenol. As the base, sodium carbonate, potassium carbonate, etc. can be used, and the usage amount is preferably 1 - 2 mol, more preferably about 1 - 1.5 mol with respect to 1 mol of m-aminophenol. As the solvent, water; alcohol solvents such as methanol, ethanol, isopropanol, etc.; mixed solvents of water and alcohol solvents (for example, isopropanol / water (v / v) = 1:1), etc. can be used. The reaction temperature can be any temperature from room temperature to the boiling point of the solvent, but is preferably 50 - 100°C, more preferably 60 - 90°C. The reaction time is usually about 1 - 48 hours, but within the above temperature range, it is preferably about 12 - 36 hours, more preferably about 18 - 24 hours. The reaction atmosphere is not particularly limited, but an inert gas atmosphere such as nitrogen gas is preferred. After the reaction is completed, post-treatment is carried out according to a conventional method, and purification is carried out as necessary to obtain Compound A-1.

[0023] In the second step, the benzene ring of Compound A-1 is formylated to synthesize Compound A-2. The formylation method is arbitrary, but the so-called Vilsmeier-Haack reaction using a dehydrating chlorinating agent such as phosphorus oxychloride or thionyl chloride and N,N-dimethylformamide (DMF) is preferred. Specifically, a solution prepared by adding a dehydrating chlorinating agent to DMF is added to a DMF solution of Compound A-1, and after heating and stirring, water is added for hydrolysis to lead to Compound A-2. The reaction temperature is preferably about 50 to 100 °C, more preferably 60 to 80 °C. The reaction time is usually about 1 to 24 hours, preferably 1 to 12 hours, more preferably 1 to 6 hours. The reaction atmosphere is not particularly limited, and it may be an air atmosphere or an inert gas atmosphere such as nitrogen gas. After the reaction is completed, post-treatment is carried out according to a conventional method, and purification is carried out as necessary to obtain Compound A-2.

[0024] In the third step, for example, according to the reaction described in Analytical Chemistry, Vol. 89, Issue 20, Pages 11098-11106, 2017, DOI: 10.1021 / acs.analchem.7b03229, etc., Compound A-2 and 2-cyanomethylbenzothiazole are dissolved in a solvent such as methanol, and then a strong acid such as concentrated hydrochloric acid is added while stirring, heated to react, and then a weak base such as sodium acetate is added, and further heated to reflux to obtain Compound A-3. In this reaction, the amount of 2-cyanomethylbenzothiazole used is preferably 1 to 2 mol, more preferably 1 to 1.5 mol, and even more preferably 1.1 to 1.3 mol per 1 mol of Compound A-2. The reaction temperature is preferably the reflux temperature of the solvent used. The reaction time is usually about 1 to 12 hours, preferably about 1 to 6 hours. The reaction atmosphere is not particularly limited, and it may be an air atmosphere or an inert gas atmosphere such as nitrogen gas. After completion of the reaction, post-treatment is carried out according to a conventional method, and purification is carried out as necessary to obtain Compound A-3.

[0025] In the fourth step, for example, according to the reaction described in Dyes and Pigments, Vol. 51, Issues 2-3, Pages 153-159, 2001, etc., the product obtained by heating and reacting Compound A-3 with sulfonic acid chloride is washed with water, and then water and dibutylamine are added for further reaction to obtain a coumarin derivative represented by the formula (1A). In this reaction, the amount of sulfonic acid chloride used is preferably 1.5 to 3 mol, more preferably 2 to 2.5 mol, per 1 mol of Compound A-3. Also, the amount of dibutylamine used is preferably 1 to 3 mol, more preferably 1.5 to 2 mol, per 1 mol of Compound A-3. The reaction temperature in the reaction with sulfonic acid chloride is preferably 50 to 180 °C, more preferably 80 to 150 °C, even more preferably 100 to 140 °C. The reaction time is usually about 1 to 12 hours, preferably about 2 to 6 hours. The reaction temperature in the reaction with dibutylamine is preferably 10 to 50 °C, more preferably 15 to 40 °C, even more preferably 20 to 30 °C. The reaction time is usually about 0.5 to 12 hours, preferably about 1 to 4 hours. The reaction atmosphere is not particularly limited, and it may be an air atmosphere or an inert gas atmosphere such as nitrogen gas. After completion of the reaction, post-treatment is carried out according to a conventional method, and purification is carried out to obtain a coumarin derivative represented by the formula (1A).

[0026] Specific examples of the naphthophosphole oxide derivative include naphthophosphole oxide derivatives represented by the following formula (1B).

[0027] [Chemical formula]

[0028] Specific examples of the above pyromethene derivative include pyromethene derivatives represented by the following formula (1C).

[0029] [Chemical formula]

[0030] Specific examples of the above perylene derivative include perylene derivatives represented by the following formula (1D).

[0031] [Chemical formula]

[0032] Considering the wavelength conversion efficiency of the obtained wavelength conversion film, the content of the above phosphor (A) is preferably 0.1 to 10% by mass, more preferably 0.2 to 7% by mass, and even more preferably 0.3 to 5% by mass in the solid content.

[0033] The above titanium oxide particles (B) are those compounded as light-scattering particles. The titanium oxide particles are not particularly limited, and for example, they may be appropriately selected from those conventionally used in wavelength conversion materials. Generally, by compounding light-scattering particles into the composition for forming a wavelength conversion film for a display, the optical path length of the light entering the wavelength conversion film in the film is extended, and the chance of wavelength conversion inside the wavelength conversion film increases. As a result, the wavelength conversion efficiency is improved. Also, due to the reflection at the interface of the wavelength conversion film, the light returning to the inside of the film is scattered again, and it is known that the light extraction efficiency is improved.

[0034] The titanium oxide particles can be used in either anatase type or rutile type. Considering the transmittance of ultraviolet light at 365 nm, rutile type titanium oxide is more preferable because it has a higher transmittance.

[0035] For the titanium oxide particles, those subjected to surface treatment may be used, but in the present invention, those without surface treatment are preferred in consideration of the storage stability of the composition. When performing surface treatment, specific materials for the surface treatment include heterogeneous inorganic oxides such as silicon oxide and zirconium oxide, metal hydroxides such as aluminum hydroxide, organosiloxane, and organic acids such as stearic acid. These surface treatment materials may be used alone or in combination of multiple types.

[0036] The average particle diameter of the titanium oxide particles is more than 50 nm and less than 200 nm. From the viewpoint of wavelength conversion efficiency, the lower limit of the average particle diameter is preferably 60 nm or more, more preferably 70 nm or more. In addition to the viewpoint of wavelength conversion efficiency, considering the patterning characteristics, from the viewpoint that the total light reflectance at i-line (365 nm) is low, an average particle diameter exceeding 100 nm is more preferable. From the viewpoint of storage stability, the upper limit of the average particle diameter is preferably 190 nm or less, more preferably 180 nm or less. In this specification, the average particle diameter is the particle diameter measured by observing with a transmission electron microscope, and the dynamic light scattering particle diameter is the particle diameter (median diameter D 50 ) at which the cumulative frequency distribution in the volume-based particle size distribution measurement by the dynamic light scattering method becomes 50%.

[0037] Commercially available products may be used for the titanium oxide particles. Specific examples thereof include PT-401M (rutile type, average particle diameter 70 nm), PT-401L (rutile type, average particle diameter 130 nm), PT-501R (rutile type, average particle diameter 180 nm), etc., but are not limited thereto. The average particle diameter of the exemplified titanium oxide particles may have a variation of ±10 nm.

[0038] Considering the wavelength conversion efficiency and storage stability, the content of the above-mentioned (B) titanium oxide particles is preferably 0.1 to 20% by mass, more preferably 0.2 to 15% by mass, even more preferably 0.3 to 10% by mass, and further preferably 3 to 10% by mass in the solid content.

[0039] As the above-mentioned (C) binder, it may be selected from known resins and the like used as a binder in the composition for forming a wavelength conversion film for a display.

[0040] As the resin, it can be appropriately selected and used from resins used as the base resin of the composition for forming a wavelength conversion film for a display. For example, polyolefin resins such as polystyrene (PS), polyethylene (PE), polypropylene (PP), and polymethylpentene; acrylic resins such as polymethyl methacrylate (PMMA), methyl methacrylate-methacrylic acid copolymer, and benzyl methacrylate-methacrylic acid copolymer, ethylene-vinyl acetate copolymer (EVA); polyvinyl butyrate (PVB); cellulose ester resins such as triacetyl cellulose (TAC) and nitrocellulose. Among these, acrylic resins are preferred, and methyl methacrylate-methacrylic acid copolymers are more preferred. As for the above-mentioned resins, commercially available products may be used, or those synthesized according to conventional methods such as radical polymerization using a polymerization initiator may be used.

[0041] The average molecular weight of the above-mentioned resin is not particularly limited, but its weight average molecular weight (Mw) is usually 5,000 to 100,000, preferably 10,000 to 50,000. Note that the average molecular weight is a polystyrene conversion value by gel permeation chromatography.

[0042] As the above-mentioned (C) binder, a polymerizable monomer and a photoinitiator may be blended and polymerized after film formation. These can also be used in combination with the above-mentioned resins. The above-mentioned polymerizable monomer is not particularly limited as long as it is used together with a photoinitiator and polymerizes upon irradiation with light, but ethylenically unsaturated monomers are preferred. In the present invention, as the above-mentioned ethylenically unsaturated monomer, any of monofunctional monomers, bifunctional monomers, and monomers having three or more functional groups can be used.

[0043] Examples of the monofunctional monomer include, for example, mono(meth)acrylate represented by the following formula (M1).

[0044] [Chemical formula]

[0045] In formula (M1), R m1 represents a hydrogen atom or a methyl group, and R m2 represents a monovalent hydrocarbon group (excluding those containing an ethylenically unsaturated group). The hydrocarbon group may be linear, branched or cyclic. From the viewpoint of excellent ejection stability in the inkjet method and excellent external quantum efficiency improvement effect, the number of carbon atoms of the hydrocarbon group is preferably 7 or less. In other words, it is preferable that the monofunctional monomer is not a monomer in which R m2 in the above formula (M1) is a hydrocarbon group having 8 or more carbon atoms. The hydrocarbon group may be substituted and may have, for example, an ether bond.

[0046] Specific examples of the monofunctional monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, phenoxyethyl (meth) acrylate, nonylphenoxyethyl (meth) acrylate, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, ethoxyethoxyethyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, benzyl (meth) acrylate, phenylbenzyl (meth) acrylate, succinic acid mono(2-acryloyloxyethyl), N-[2-(acryloyloxy)ethyl]phthalimide, N-[2-(acryloyloxy)ethyl]tetrahydrophthalimide, and the like. Among these, ethoxyethoxyethyl (meth) acrylate is preferably used.

[0047] As the monofunctional monomer, from the viewpoint of easily improving the ejection stability in the inkjet method, a monomer having a viscosity of 10,000 mPa·s or less, 8,000 mPa·s or less, 5,000 mPa·s or less, or 1,000 mPa·s or less is preferable. In the present specification, the viscosity of a monomer having an ethylenically unsaturated group such as a monofunctional monomer is, for example, the viscosity at 25°C measured by an EMS viscometer.

[0048] Examples of the bifunctional monomer include di(meth)acrylate represented by the following formula (M2).

[0049]

Chem.

[0050] In formula (M2), a plurality of Rs m3 each independently represent a hydrogen atom or a methyl group, and R m4 represents a divalent hydrocarbon group (however, excluding those containing an ethylenically unsaturated group). The hydrocarbon group may be linear, branched, or cyclic. From the viewpoints of excellent discharge stability and excellent improvement effect of external quantum efficiency, the number of carbon atoms of the hydrocarbon group is preferably 7 or less. The hydrocarbon group may be substituted and may have, for example, an ether bond.

[0051] Specific examples of the bifunctional monomer include 1,3-butylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,8-octanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol hydroxypivalate diester diacrylate, di(meth)acrylate in which two hydroxyl groups of tris(2-hydroxyethyl) isocyanurate are substituted by (meth)acryloyloxy groups, di(meth)acrylate in which two hydroxyl groups of a diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol are substituted by (meth)acryloyloxy groups, di(meth)acrylate in which two hydroxyl groups of a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A are substituted by (meth)acryloyloxy groups, di(meth)acrylate in which two hydroxyl groups of a triol obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane are substituted by (meth)acryloyloxy groups, di(meth)acrylate in which two hydroxyl groups of a diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of bisphenol A are substituted by (meth)acryloyloxy groups, and the like. Among these, dipropylene glycol di(meth)acrylate is preferably used.

[0052] As the bifunctional monomer, a monomer having a viscosity of 10,000 mPa·s or less, 5,000 mPa·s or less, or 1,000 mPa·s or less is preferable from the viewpoint of easily improving the ejection stability in the inkjet method. The above viscosity is the viscosity at 25°C.

[0053] Examples of the trifunctional monomer include tri(meth)acrylate represented by the following formula (M3).

[0054] [Chemical formula]

[0055] In formula (M3), a plurality of R m5 each independently represents a hydrogen atom or a methyl group, and R m6 represents a trivalent hydrocarbon group (excluding those containing an ethylenically unsaturated group). The hydrocarbon group may be linear, branched, or cyclic. From the viewpoint of excellent ejection stability and excellent external quantum efficiency improvement effect, the number of carbon atoms of the hydrocarbon group is preferably 4 or less. The hydrocarbon group may be substituted and may have, for example, an ether bond.

[0056] Specific examples of the trifunctional monomer include glycerin tri(meth)acrylate, trimethylolethane tri(meth)acrylate, etc. Among these, glycerin tri(meth)acrylate is preferably used.

[0057] As the trifunctional monomer, a monomer having a viscosity of 10,000 mPa·s or less, 5,000 mPa·s or less, or 1,000 mPa·s or less is preferable from the viewpoint of easily improving the ejection stability in the inkjet method. The above viscosity is the viscosity at 25°C.

[0058] As the photoinitiator, a photo radical polymerization initiator, a photo cationic polymerization initiator, etc. can be used. Considering the compatibility with the general manufacturing method of the wavelength conversion member, it is preferable to use a photo radical polymerizable compound, and from the viewpoint of forming a pixel portion (cured product of the ink composition) without being affected by oxygen inhibition in the curing process, it is preferable to use a photo cationic polymerizable compound.

[0059] As the photo radical polymerization initiator, a molecular cleavage type or hydrogen abstraction type photo radical polymerization initiator is preferably used.

[0060] Examples of the molecular cleavage type photo radical polymerization initiator include benzoin isobutyl ether, 2,4 - diethyl thioxanthone, 2 - isopropyl thioxanthone, 2,4,6 - trimethylbenzoyl diphenylphosphine oxide, ethyl phenyl(2,4,6 - trimethylbenzoyl)phosphinate, 2 - benzyl - 2 - dimethylamino - 1 - (4 - morpholinophenyl) - butan - 1 - one, bis(2,6 - dimethoxybenzoyl) - 2,4,4 - trimethylpentylphosphine oxide, bis(2,4,6 - trimethylbenzoyl)phenylphosphine oxide, (2,4,6 - trimethylbenzoyl)ethoxyphenylphosphine oxide. As other molecular cleavage type photo radical polymerization initiators, for example, 1 - hydroxycyclohexyl phenyl ketone, benzoin ethyl ether, benzyl dimethyl ketal, 2 - hydroxy - 2 - methyl - 1 - phenylpropan - 1 - one, 2,2 - dimethoxy - 1,2 - diphenylethane - 1 - one, 2,2 - dimethoxy - 2 - phenylacetophenone, 1 - (4 - isopropylphenyl) - 2 - hydroxy - 2 - methylpropan - 1 - one, 2 - methyl - 1 - (4 - methylthiophenyl) - 2 - morpholinopropan - 1 - one may be used in combination.

[0061] Examples of the hydrogen abstraction type photo radical polymerization initiator include benzophenone, 4-phenylbenzophenone, isophthalophenone, and 4-benzoyl-4'-methyl-diphenyl sulfide. A molecular cleavage type photo radical polymerization initiator and a hydrogen abstraction type photo radical polymerization initiator may be used in combination.

[0062] The photo radical polymerization initiator can also be obtained as a commercial product. Such commercial products include acylphosphine oxide compounds such as Omnirad (registered trademark. The same shall apply hereinafter.) TPO-H, Omnirad TPO-L, and Omnirad 819 manufactured by IGM resin; alkylphenone compounds such as Omnirad 651, Omnirad 184, Omnirad 1173, Omnirad 2959, Omnirad 127, Omnirad 907, Omnirad 369, Omnirad 369E, and Omnirad 379EG; intramolecular hydrogen abstraction type compounds such as Omnirad MBF and "Omnirad 754"; oxime ester compounds such as Irgacure (registered trademark. The same shall apply hereinafter.) OXE01, Irgacure OXE02, Irgacure OXE03, and Irgacure OXE04 manufactured by BASF Japan, TR-PBG-304 and TR-PBG-305 manufactured by Changzhou Qiangli Electronic New Materials Co., Ltd., and NCI-831 and NCI-930 manufactured by ADEKA Corporation.

[0063] In addition to these, examples of the oxime ester compounds include the compounds described in JP-T-2004-534797, the compounds described in JP-A-2000-80068, the compounds described in WO 2012 / 45736, the compounds described in WO 2015 / 36910, the compounds described in JP-A-2006-36750, the compounds described in JP-A-2008-179611, the compounds described in WO 2009 / 131189, the compounds described in JP-T-2012-526185, the compounds described in JP-T-2012-519191, the compounds described in WO 2006 / 18973, the compounds described in WO 2008 / 78678, the compounds described in JP-A-2011-132215, and other oxime ester compounds.

[0064] Examples of the cationic photoinitiators include polyaryl sulfonium salts such as triphenylsulfonium hexafluoroantimonate and triphenylsulfonium hexafluorophosphate; polyaryl iodonium salts such as diphenyliodonium hexafluoroantimonate and P-nonylphenyliodonium hexafluoroantimonate.

[0065] The cationic photoinitiator can also be obtained as a commercial product. Examples of such commercial products include sulfonium salt-based cationic photoinitiators such as CPI-100P manufactured by San-Apro Ltd., Omnicat (registered trademark, the same shall apply hereinafter) 270 manufactured by IGM Resin B.V., and Irgacure 290 manufactured by BASF Japan Ltd.; iodonium salt-based cationic photoinitiators such as Omnicat 250 manufactured by IGM Resin B.V.

[0066] From the viewpoint of the curability of the composition, the content of the above photoinitiator is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass based on 100% by mass of the polymerizable monomer. Further, from the viewpoint of the storage stability of the composition, the upper limit of the content is preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0067] The content of the above (C) binder is preferably 70 to 99.8% by mass, more preferably 85 to 99.8% by mass, and even more preferably 90 to 99% by mass in the solid content.

[0068] In addition to the above components (A) to (C), the composition for forming a wavelength conversion film for a display of the present invention may contain various known additives such as a light stabilizer, an antioxidant, a surfactant, a flame retardant, a clarifying agent, an ultraviolet absorber, a crosslinking agent, and a filler, if necessary. As the surfactant, a fluorine-based surfactant is preferable, and a nonionic fluorine-based surfactant is more preferable. Specific examples thereof include the Fタージェント series, 212M, 215M, 250, 222F, FTX-218, DFX-18, etc. manufactured by Neos Co., Ltd., but are not limited thereto. When using a surfactant, its blending amount is not particularly limited, but it is preferably 0.01 to 1% by mass, more preferably 0.01 to 0.5% by mass in the solid content of the composition for forming a wavelength conversion film for a display.

[0069] Furthermore, the composition for forming a wavelength conversion film for a display according to the present invention may contain a solvent if necessary. Specific examples thereof include aromatic or halogenated aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and chlorobenzene; aliphatic hydrocarbons such as n-heptane, n-hexane, and cyclohexane; ether solvents such as diethyl ether, tetrahydrofuran, dioxane, and 1,2-dimethoxyethane; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; ester solvents such as ethyl acetate, normal hexyl acetate, ethyl lactate, γ-butyrolactone, propylene carbonate, and diisopropyl malonate; halogenated hydrocarbon solvents such as methylene chloride, dichloromethane, 1,2-dichloroethane, and chloroform; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone; alcohol solvents such as methanol, ethanol, isopropanol, n-propanol, cyclohexanol, diacetone alcohol, and 2-benzooxyethanol; glycol ether solvents such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol diglycidyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, dipropylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate; glycol solvents such as ethylene glycol, propylene glycol, hexylene glycol, 3-octylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, 1,3-butanediol, 2,3-butanediol, and 1,4-butanediol. These organic solvents may be used alone or in combination of two or more.

[0070] When the composition for forming a wavelength conversion film for a display contains a solvent, the solid content concentration of the composition for forming a wavelength conversion film for a display varies depending on the thickness of the target wavelength conversion film, the coating method, etc., and thus cannot be generally defined, but is usually 10 to 70% by mass, preferably 20 to 60% by mass.

[0071] The upper limit of the viscosity at 25 °C of the above composition for forming a wavelength conversion film for a display is 10,000 mPa·s or less, preferably 1,000 mPa·s or less. Considering the storage stability, the lower limit is preferably 5 mPa·s or more, more preferably 10 mPa·s or more. In the present invention, the viscosity means a measured value by an EMS viscometer.

[0072] The composition for forming a wavelength conversion film for a display of the present invention can be prepared by mixing the above components (A) to (C), other additives such as surfactants used as necessary, and a solvent in an arbitrary order.

[0073] By applying the above-described composition for forming a wavelength conversion film for a display of the present invention onto a substrate, for example, evaporating the solvent by heating or the like as necessary, and further irradiating with active energy rays (for example, ultraviolet light) as necessary, a wavelength conversion film can be obtained. Examples of the coating method include methods using a reverse roll coater, a blade coater, a slit die coater, a direct gravure coater, an offset gravure coater, a kiss coater, a natural roll coater, an air knife coater, a roll blade coater, a valibar roll blade coater, a toast stream coater, a rod coater, a wire bar coater, an applicator, a dip coater, a curtain coater, a spin coater, a knife coater, an inkjet, etc.

[0074] Heating can be performed using a general heating device such as an oven or a hot plate. The heating conditions are not particularly limited as long as a film can be formed, but preferably 5 minutes to 2 hours at 60 to 200°C, more preferably 15 minutes to 1 hour at 80 to 200°C. Note that stepwise heat curing may also be performed.

[0075] The irradiation of ultraviolet light is not particularly limited as long as a film can be formed, but a light source such as a mercury lamp, a metal halide lamp, a xenon lamp, or an LED can be used, and if necessary, a band-pass filter can be combined to irradiate light from which light other than the target exposure wavelength has been removed. The wavelength of the irradiated light is preferably 200 to 440 nm, particularly preferably including light having a wavelength of 300 to 400 nm. The exposure amount is preferably 10 to 4,000 mJ / cm 2 is preferred.

[0076] The above-mentioned heating step and the ultraviolet light exposure step may be combined in any order. For example, heating may be performed first and then ultraviolet light irradiation may be performed, or ultraviolet light irradiation may be performed first and then heating may be performed, or heating may be performed first, then ultraviolet light irradiation may be performed, and then further heating may be performed.

[0077] The thickness of the wavelength conversion film is not particularly limited, but is usually 1 to 1,000 μm, preferably 3 to 500 μm, more preferably 5 to 100 μm. The haze value of the wavelength conversion film is not particularly limited, but from the viewpoint of increasing the amount of light that can be absorbed by the phosphor by scattering incident light in the film, it is preferably 18% or more, more preferably 30% or more, still more preferably 40% or more. The upper limit of the haze value is not particularly limited, but is usually about 95%. In the present invention, the haze value is a value measured according to ASTM D1003-61. In the present invention, as the measurement conditions for the above haze value, for example, the conditions for measuring a film having a film thickness of 6 μm formed from a composition having a titanium oxide particle content of 3.16 to 4.74% by mass can be mentioned.

[0078] The base material may be appropriately selected from those used as the base substrate for forming this type of film. However, a glass substrate or a polymer plate with a light transmittance of 50% or more in the visible region of 400 to 800 nm is preferred. Specific examples of the glass include soda-lime glass, barium-strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz, and the like. Specific examples of the polymer include polycarbonate, acrylic, polyethylene terephthalate, polyethersulfide, polysulfone, and the like.

[0079] Since the wavelength conversion film obtained by the composition of the present invention is excellent in wavelength conversion efficiency, it can be suitably used as a wavelength conversion film (color conversion film) for displays such as micro LED displays, organic EL displays, and liquid crystal displays, and lighting.

Examples

[0080] Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[0081] [Molecular weight measurement] In this example, the molecular weight of the polymer was measured using a GPC system manufactured by JASCO Corporation as the apparatus, and Shodex (registered trademark) KF-804L and 803L as the columns, and was carried out under the following conditions. Column oven: 40 °C Flow rate: 1 ml / min Eluent: Tetrahydrofuran

[0082] The meanings of the abbreviations used in this example are as follows. Note that for Dye A 1 The chemical shift of the 1H-NMR spectrum is as follows. An AVANCE III HD 500 MHz (manufactured by Bruker) was used as the measuring apparatus. 11H NMR (in CDCl3): δ / ppm 8.93 (1H, s), 8.41 (1H, d, J = 1.6 Hz), 8.05 (1H, d, J = 8.5 Hz), 7.87 (1H, dd, J = 1.6, 8.5 Hz), 7.48 (1H, d, J = 9.0 Hz), 6.67 (1H, dd, J = 2.3, 9.0 Hz), 6.54 (1H, d, J = 2.3 Hz), 3.40 (2H, t, J = 7.8 Hz), 3.24 (2H, d, J = 7.0 Hz), 3.17 (4H, t, J = 7.6 Hz), 1.76 - 1.62 (9H, m), 1.52 (4H, qui, J = 7.8 Hz), 1.34 - 1.16 (12H, m), 1.00 (2H, q, J = 11.1 Hz), 0.92 (3H, t, J = 6.9 Hz), 0.92 (6H, t, J = 7.4 Hz) MMA: Methyl methacrylate MAA: Methacrylic acid AIBN: α,α’-Azobisisobutyronitrile V#230: Viscote #230 (1,6 - Hexanediol diacrylate, manufactured by Osaka Organic Chemical Industry Co., Ltd.) OXE - 02: Irgacure OXE02 (manufactured by BASF) PGME: Propylene glycol monomethyl ether CPN: Cyclopentanone TTO - 55(A): Titanium oxide particles (rutile type, average particle diameter 50 nm, AlOH3 - coated, manufactured by Ishihara Sangyo Co., Ltd.) PT - 401M: Titanium oxide particles (rutile type, average particle diameter 70 nm, manufactured by Ishihara Sangyo Co., Ltd.) PT - 401L: Titanium oxide particles (rutile type, average particle diameter 130 nm, manufactured by Ishihara Sangyo Co., Ltd.) PT - 501R: Titanium oxide particles (rutile type, average particle diameter 180 nm, manufactured by Ishihara Sangyo Co., Ltd.) CR - EL: Titanium oxide particles (rutile type, average particle diameter 250 nm, manufactured by Ishihara Sangyo Co., Ltd.) Light - scattering particle 1: Titanium oxide particles (anatase type, average particle diameter 100 nm, SiO2 - SnO2 - coated) DFX - 18: Phthalgen DFX - 18 (manufactured by Neos Co., Ltd.)

[0083] Dye A: A compound represented by the following formula (1A)

Chemical formula

[0084] Dye B: A compound represented by the following formula (1B), C-Naphox-TEG, manufactured by Tokyo Chemical Industry Co., Ltd.

Chemical formula

[0085] Dye C: A compound represented by the following formula (1C), BDP FL, manufactured by Tokyo Chemical Industry Co., Ltd.

Chemical formula

[0086] Dye D: A compound represented by the following formula (1D), FL 305, manufactured by BASF

Chemical formula

[0087] [Synthesis Example 1] Preparation of polymer solution 80.0 g of MMA, 20.0 g of MAA, and 2.5 g of AIBN were dissolved in 190.0 g of CPN, and reacted at 90 °C for 20 hours to obtain an acrylic polymer solution P1 (solid content concentration: 30% by mass). The Mn of the obtained acrylic polymer was 9,900, and the Mw was 17,078.

[0088] [Synthesis Example 2] Preparation of light-scattering particles 1 1,429.1 g of pure water was placed in a 5-liter container, and 315.6 g of a 35 mass% aqueous solution of tetraethylammonium hydroxide, 39.4 g of glycine, and 213.2 g of titanium tetraisopropoxide (containing 59.9 g in terms of TiO2) were added with stirring. The resulting mixed solution had a molar ratio of tetraethylammonium hydroxide / titanium atoms of 1.00 and a molar ratio of glycine / titanium atoms of 0.70. The mixed solution was held at 90 °C for 2 hours and then at 95 °C for 5 hours to prepare a titanium mixed solution. The pH of the prepared titanium mixed solution was 11.2 and the TiO2 concentration was 3.0 mass%. 1,500 g of the above titanium mixed solution was charged into a 3-liter SUS autoclave container, and hydrothermal treatment was carried out at 150 °C for 5 hours. After cooling to room temperature, the taken-out solution after hydrothermal treatment was an aqueous dispersion of milky white titanium oxide colloid particles. The obtained dispersion had a pH of 12.2, a TiO2 concentration of 3.0 mass%, a dynamic light scattering particle size of 141 nm, and when observed by a transmission electron microscope (JEM-F200, manufactured by JEOL Ltd.), tabular particles with an average primary particle size of 94 nm were observed. In addition, a Zetasizer manufactured by Malvern Instruments Ltd. was used as the measuring device for the dynamic light scattering method. Next, the obtained aqueous dispersion of titanium oxide colloid particles was subjected to washing with water by ultrafiltration to remove excess electrolytes, and a dispersion with a TiO2 concentration of 3.0 mass% was obtained. The obtained titanium oxide colloid particles were used as the core titanium oxide particles.

[0089] On one hand, 27.9 g of an aqueous sodium silicate solution (JIS No. 3 sodium silicate, containing 34% by mass of SiO2, manufactured by Fuji Chemical Co., Ltd.) was diluted with 27.9 g of pure water. Then, 8.6 g of sodium stannate trihydrate (containing 55% by mass of SnO2, manufactured by Showa Chemical Industry Co., Ltd.) was added and dissolved with stirring to obtain an aqueous sodium silicate - sodium stannate solution. 64.4 g of the obtained aqueous sodium silicate - sodium stannate solution was diluted with 411 g of pure water and passed through a column filled with a hydrogen - type cation exchange resin (Amberlite (registered trademark) IR - 120B) to obtain 570 g of an aqueous dispersion of silicon dioxide - stannic oxide composite oxide colloidal particles. The obtained aqueous dispersion had a pH of 2.7 and a total metal oxide concentration of 2.5% by mass. Next, 2.9 g of diisopropylamine was added to the obtained aqueous dispersion of silicon dioxide - stannic oxide composite oxide colloidal particles. The obtained dispersion was an aqueous dispersion of alkaline silicon dioxide - stannic oxide composite oxide colloidal particles, with a pH of 8.2 and colloidal particles having a primary particle diameter of 5 nm or less. The obtained silicon dioxide - stannic oxide composite oxide colloidal particles were used as coated particles.

[0090] To 1,200 g of the aqueous dispersion of the titanium oxide particles serving as the core, 144.0 g of the coated particles composed of the prepared silicon dioxide - stannic oxide composite oxide were added. Then, it was held at a temperature of 95°C for 2 hours to obtain an aqueous dispersion of modified titanium oxide colloidal particles. Thereafter, the obtained aqueous dispersion of modified titanium oxide colloidal particles was passed through a column filled with a hydrogen - type cation exchange resin (Amberlite (registered trademark) IR - 120B) to obtain an acidic aqueous dispersion of modified titanium oxide colloidal particles. Next, the obtained aqueous dispersion was put into an evaporator equipped with an eggplant - shaped flask and concentrated. By distilling off water at 590 Torr while adding methanol, 129.8 g of a methanol dispersion of modified titanium oxide colloidal particles was obtained. The obtained methanol dispersion had a viscosity of 1.2 mPa·s, a pH of 6.4 (diluted with water having the same mass as the dispersion), a solid content concentration of 30.5% by mass, a water content of 0.8% by mass, a dynamic light scattering particle diameter of 140 nm, and when observed by a transmission electron microscope, tabular particles with an average primary particle diameter of 101 nm were observed.

[0091] [Examples 1 to 10, Comparative Examples 1 to 9] Preparation and Evaluation of Composition for Forming Wavelength Conversion Film (1) Preparation of Composition for Forming Wavelength Conversion Film The components were mixed in the composition shown in Table 1, and the resulting mixture was filtered using a polytetrafluoroethylene (PTFE) filter with a pore size of 5.0 μm to prepare a composition for forming a wavelength conversion film. The composition ratios in Tables 1 and 2 represent mass ratios based on solid content.

[0092] [Table 1]

[0093] [Table 2]

[0094] (2) Evaluation 1: Evaluation of Viscosity The compositions for forming wavelength conversion films of Examples 1 to 10 and Comparative Examples 1 to 9 were measured under the following conditions, and this was taken as the viscosity of each composition for forming a wavelength conversion film. Apparatus: EMS-1000 manufactured by Kyoto Electronics Industry Co., Ltd. Measurement temperature: 25°C Probe size: 2.0 mm Φ Rotation speed: 500 rpm Measurement time: 5 seconds

[0095] (3) Evaluation 2: Evaluation of Film Properties The compositions for forming wavelength conversion films of Examples 1 to 7, 9 and 10, and Comparative Examples 1, 2 and 4 to 8 were applied onto a quartz substrate using a spin coater, and then pre-baked on a hot plate at 110°C for 120 seconds to obtain a coating film sample with a film thickness of 6 μm. Thereafter, the coating film samples of Examples 1 to 6, 9 and Comparative Examples 1, 2, 4 to 6, 9 were post-baked at 160°C for 60 minutes. The coating film samples of Examples 7 and Comparative Example 7 were post-baked at 120°C for 60 minutes. The composition for forming a wavelength conversion film of Example 8 and Comparative Examples 3 and 9 was applied onto a non-alkali glass substrate using a bar coater, and then irradiated with ultraviolet light at 365 nm with an exposure amount of 1000 mJ / cm 2 over the entire surface of the resin film by a batch type UV irradiation apparatus (high-pressure mercury lamp 2 kW × 1 lamp, manufactured by Eye Graphics Co., Ltd.), thereby forming a cured film on the non-alkali glass substrate. For the obtained coating film sample, the haze value was measured in accordance with the measurement method based on ASTM D1003-61 using a turbidimeter NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd.

[0096] Next, the coating film sample was placed on a blue LED light (emission peak wavelength 450 nm) manufactured by CCS, Inc., the LED light was turned on, and the light emitted through the coating film sample was measured using a spectro-radiation illuminometer USR-45 manufactured by Ushio Inc., and the result was designated as (1). Similarly, the light emitted only from the LED light excluding the coating film sample was measured in the same manner, and the result was designated as (2). From the obtained spectro-radiation illuminance spectrum, the number of photons of light having a wavelength of 480 nm or less in result (2) was defined as the "excitation light photon number". Similarly, the number of photons of light having a wavelength of 480 nm or less in result (1) was defined as the "transmitted light photon number". Similarly, the number of photons of light having a wavelength exceeding 480 nm in result (1) was defined as the "emission light photon number". The "blue light absorption rate" and the "conversion efficiency" were calculated by the following formulas. Blue light absorption rate = (Excitation light photon number - Transmitted light photon number) ÷ Excitation light photon number Conversion efficiency = Emission light photon number ÷ Excitation light photon number

[0097] Furthermore, the numerical values obtained by dividing the "conversion efficiency" of the coating film samples of Examples 1 to 3, 9 and 10, and Comparative Example 4 by the "conversion efficiency" of the coating film sample of Comparative Example 4, the "conversion efficiency" of the coating film samples of Example 4 and Comparative Example 5 by the "conversion efficiency" of the coating film sample of Comparative Example 5, the "conversion efficiency" of the coating film samples of Example 5 and Comparative Example 6 by the "conversion efficiency" of the coating film sample of Comparative Example 6, the "conversion efficiency" of the coating film samples of Example 6 and Comparative Example 7 by the "conversion efficiency" of the coating film sample of Comparative Example 7, the "conversion efficiency" of the coating film samples of Example 7 and Comparative Example 8 by the "conversion efficiency" of the coating film sample of Comparative Example 8, the "conversion efficiency" of the coating film samples of Example 8 and Comparative Example 9 by the "conversion efficiency" of the coating film sample of Comparative Example 9 were defined as the "conversion efficiency enhancement factor". Based on the obtained conversion efficiency enhancement factor, the film properties of the coating film samples were evaluated. The criteria are as follows. The obtained results are shown in Tables 3 and 4. 〈Judgment Criteria〉 A: The conversion efficiency enhancement factor is greater than 2.5 B: The conversion efficiency enhancement factor is greater than 2.1 and less than or equal to 2.5 C: The conversion efficiency enhancement factor is less than or equal to 2.1

[0098] (4) Evaluation 3: Evaluation of film-forming property In Evaluation 2, when the wavelength conversion film-forming compositions of Examples 1 to 10 and Comparative Examples 1 to 9 were applied onto a substrate, the state of the coating film was visually confirmed to evaluate the film-forming property. The criteria are as follows. The obtained results are shown in Tables 3 and 4. 〈Judgment Criteria〉 A: A uniform coating film was obtained and the film-forming property was good B: Coating unevenness occurred and the film-forming property was poor Note that for the coating film sample of Comparative Example 3, radial coating unevenness was significantly observed visually on the film surface, and the film-forming property was extremely poor. Therefore, it was impossible to measure the "conversion efficiency" in Evaluation 2 for Comparative Example 3.

[0099] (5) Evaluation 4: Evaluation of storage stability The wavelength conversion film-forming compositions of Examples 1 to 10 and Comparative Examples 1 to 3 were stored at 25°C for one week, and the state of the composition during storage (presence or absence of precipitation of titanium oxide particles) was visually confirmed. The criteria for judgment are as follows. The obtained results are shown in Tables 3 and 4. <Judgment Criteria> A: No precipitation is observed until one week has passed. B: No precipitation is observed after one day has passed, and precipitation is observed after two days have passed. C: Precipitation is observed after one day has passed.

[0100] (6) Evaluation 5: Evaluation of total light reflectance For the coating film samples obtained by the same method as in Evaluation 2, the total light reflectance at a wavelength of 365 nm was measured using an ultraviolet-visible spectrophotometer (UV-2600 manufactured by Shimadzu Corporation). Based on the obtained total light reflectance, the film properties of the coating film samples were evaluated. The criteria for judgment are as follows. The obtained results are shown in Tables 3 and 4. <Judgment Criteria> A: The total light reflectance is 15% or less. B: The total light reflectance is greater than 15%.

[0101] [Table 3]

[0102] [Table 4]

[0103] As shown in Table 3 and Table 4, in Examples 1 to 10 that meet the requirements of the present invention, the conversion efficiency enhancement intensity in Evaluation 2 was high, the storage stability in Evaluation 4 was good, and the compatibility between the conversion efficiency and the storage stability was observed. On the contrary, in Comparative Examples 1 to 9 that do not meet the requirements of the present invention, the conversion efficiency enhancement intensity in Evaluation 2 was low, or the storage stability in Evaluation 4 was poor, and the compatibility between the conversion efficiency and the storage stability was not observed. Furthermore, in Comparative Example 3, the viscosity was 10,143 mPa·s, and since it did not meet the requirements of the present invention, the film-forming property was extremely poor, and it was difficult to evaluate the physical properties of the coating film.

Claims

1. (A) an organic pigment, (B) titanium oxide particles, and (C) a binder, wherein the surface of the above-mentioned (B) titanium oxide particles may be coated with an inorganic compound, the average particle diameter of the titanium oxide particles is 60 to 190 nm, a composition for forming a wavelength conversion film for a display having a viscosity at 25°C of 10,000 mPa·s or less, a composition for forming a wavelength conversion film for a display, wherein the haze value of the film formed from the composition for forming a wavelength conversion film for a display is 18% or more.

2. The composition for forming a wavelength conversion film for a display according to Claim 1, wherein the average particle diameter of the above-mentioned (B) titanium oxide particles is more than 100 nm and 190 nm or less.

3. The composition for forming a wavelength conversion film for a display according to Claim 1 or 2, wherein the above-mentioned (B) titanium oxide particles are of the rutile type and the surface of the titanium oxide particles is not coated.

4. The composition for forming a wavelength conversion film for a display according to Claim 1 or 2, wherein the content of the above-mentioned (B) titanium oxide particles is 3 to 10% by mass in the solid content.

5. A wavelength conversion film having a haze value of 18% or more, obtained from the composition for forming a wavelength conversion film for a display according to Claim 1 or 2.

6. A display provided with the wavelength conversion film according to Claim 5.

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