JP7708205B2 - Composition for forming wavelength conversion film for display - Google Patents

Description

The present invention relates to a composition for forming a wavelength conversion film for displays, and more specifically, to a composition for forming a wavelength conversion film for displays that is suitable for use in various displays such as liquid crystal displays, organic electroluminescence displays, and micro LED displays.

Micro LED displays are capable of high contrast and high brightness, and have a wide range of applications, such as large screens and transparent displays, so they are expected to be the next-generation display to succeed liquid crystal displays and organic electroluminescence displays.
In a microLED display, typically, a tiny LED chip is placed at each pixel.
One method of arranging these LED chips is the RGB-LED method, in which three color LEDs are implemented. However, this method has issues such as the complexity of LED light emission control and the low performance of red LEDs, and wavelength conversion methods that can solve these issues have attracted attention.
The wavelength conversion method uses only a blue LED chip and extracts red and green light using a wavelength conversion material, and has the advantage that the three primary colors can be produced using only a blue LED chip.

Conventionally, technologies using organic light-emitting materials have been proposed as wavelength conversion materials, and for example, those using pyridine-phthalimide condensates (Patent Document 1, etc.), those using coumarin derivatives (Patent Document 2, etc.), those using perylene derivatives (Patent Document 3, etc.), those using rhodamine derivatives (Patent Document 4), and those using pyrromethene derivatives (Patent Documents 5 and 6, etc.) have been disclosed.

These wavelength converting materials are generally required to have properties 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 acrylic ester serves as a high-performance red-color conversion material with good light resistance.
Furthermore, a technique of adding a light stabilizer to prevent deterioration of the organic light-emitting material and improve durability has also been disclosed (Patent Document 8, etc.).
Furthermore, it is known that adding fine particles to the wavelength conversion material increases the optical path length due to light scattering within the color conversion layer, thereby improving the blue light absorptivity, and improves the luminous efficiency by re-scattering the light reflected at the interface (Patent Documents 9 and 10, etc.).

However, with the recent development of display technology, compositions for forming wavelength conversion films for displays require further improvements in the wavelength conversion efficiency of wavelength conversion materials from the viewpoint of improving display performance, and further improvements in the storage stability of the compositions are required from the viewpoint of productivity.

JP 2002-348568 A JP 2007-273440 A JP 2002-317175 A JP 2001-164245 A JP 2011-241160 A JP 2014-136771 A JP 2006-89724 A JP 2011-149028 A International Publication No. 2020/189678 International Publication No. 2019/181698

The present invention has been made in consideration of the above circumstances, and aims to provide a composition for forming a wavelength conversion film for displays that provides a wavelength conversion film having excellent wavelength conversion efficiency and also has excellent storage stability.

As a result of extensive research into solving the above problems, the inventors discovered that a composition for forming a wavelength conversion film for displays, which contains titanium oxide particles having an average particle size within a specific range and has a viscosity adjusted to a specific range, can solve the above problems, and thus completed the present invention.

That is, the present invention provides the following composition for forming a wavelength conversion film for a display.
1. (A) A fluorescent material, (B) titanium oxide particles, and (C) a binder are contained,
The titanium oxide particles (B) may have a surface coated with an inorganic compound, and have an average particle size of more than 50 nm and less than 200 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.
2. The composition for forming a wavelength conversion film for a display according to 1, wherein the average particle size of the titanium oxide particles (B) is 60 to 190 nm.
3. The composition for forming a wavelength conversion film for a display according to 1 or 2, wherein the titanium oxide particles (B) 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 titanium oxide particles (B) is 3 to 10 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 phosphor (A) is an organic dye.
6. A composition for forming a wavelength conversion film for a display according to any one of 1 to 5, wherein the haze value of a film formed from the composition is 18% or more.

According to the present invention, it is possible to provide a composition for forming a wavelength conversion film for displays that not only provides a wavelength conversion film having excellent wavelength conversion efficiency but also has excellent storage stability.

The present invention will be described in further detail below.
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, and is characterized in that the surfaces of the titanium oxide particles (B) may be coated with an inorganic compound, and the average particle diameter 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 surfaces of the titanium oxide particles (B) are 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 that constitute the composition for forming a wavelength conversion film for a display.

The (A) phosphor can be appropriately selected from conventionally known inorganic phosphors, organic dyes, semiconductor nanoparticles (quantum dots, quantum rods, etc.), etc., but from the viewpoint of high resolution displays and storage stability of the composition, organic dyes are preferred. Note that in the present invention, it is preferable that the phosphor does not contain semiconductor nanoparticles.

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

In the present invention, among the above organic dyes, coumarin derivatives, naphthophosphoroxide derivatives, pyrromethene derivatives and perylene derivatives are preferred.

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

In formula (1), ^R1 and ^R2 each independently represent an alkyl group having 2 to 10 carbon atoms, and ^R3 and ^R4 each independently represent an alkyl group having 2 to 8 carbon atoms, but ^R3 and ^R4 may be bonded to each other to form a ring together with the nitrogen atom.
The alkyl group having 2 to 10 carbon atoms may be linear, branched, or cyclic, and specific examples thereof include ethyl, n-propyl, i-propyl, n-butyl, n-hexyl, n-octyl, 2-ethylhexyl, cyclohexylmethyl, and neopentyl groups.
The alkyl group having 2 to 8 carbon atoms may be linear, branched or cyclic, and specific examples thereof include those having 2 to 8 carbon atoms among the alkyl groups having 2 to 10 carbon atoms.

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, or 2-ethylhexyl groups, and more preferably n-butyl or n-hexyl groups.
A suitable example of the coumarin derivative represented by formula (1) is a compound represented by the following formula (1A), but is not limited thereto.

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

That is, in the first step, compound A-1 is synthesized by reacting m-aminophenol with a halogenated cyclohexylmethane such as bromocyclohexylmethane and a 1-halogenated hexane such as 1-bromohexane in a solvent in the presence of a base, in accordance with the reaction described in paragraph [0037] of Chinese Patent Publication No. 105001666A or the like.
In this reaction, the amount of each of the halogenated cyclohexylmethane and the 1-halogenated hexane to be used is preferably about 0.5 mol per mol of m-aminophenol.
As the base, sodium carbonate, potassium carbonate, etc. can be used, and the amount used is preferably 1 to 2 mol, more preferably about 1 to 1.5 mol, per mol of m-aminophenol.
Examples of the solvent that can be used include water; alcoholic solvents such as methanol, ethanol, and isopropanol; and mixed solvents of water and alcoholic solvents (for example, isopropanol/water (v/v)=1:1).
The reaction temperature may be any temperature between room temperature and the boiling point of the solvent, but is preferably 50 to 100°C, more preferably 60 to 90°C.
The reaction time is usually about 1 to 48 hours, but within the above temperature range, about 12 to 36 hours is preferable, and about 18 to 24 hours is more preferable.
The reaction atmosphere is not particularly limited, but an inert gas atmosphere such as nitrogen gas is preferable.
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.

In the second step, the benzene ring of compound A-1 is formylated to synthesize compound A-2.
Any method may be used for the formylation, 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 DMF solution of compound A-1 is added to a solution prepared by adding a dehydrating chlorinating agent to DMF, and the mixture is heated and stirred, and then water is added for hydrolysis to produce 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, and more preferably 1 to 6 hours.
The reaction atmosphere is not particularly limited, and may be either 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.

In the third step, for example, in accordance with the reaction described in Analytical Chemistry, Vol. 89, Issue 20, Pages 11098-11106, 2017, DOI: 10.1021/acs.analchem.7b03229, 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 with stirring, and the mixture is heated to react, and then a weak base such as sodium acetate is added, and the mixture is further heated under 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, relative to 1 mol of compound A-2.
The reaction temperature is preferably a temperature at which the solvent used refluxes.
The reaction time is usually about 1 to 12 hours, preferably about 1 to 6 hours.
The reaction atmosphere is not particularly limited, and may be either 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-3.

In the fourth step, for example, in accordance with the reaction described in Dyes and Pigments, Vol. 51, Issues 2-3, Pages 153-159, 2001, etc., compound A-3 is reacted with sulfonic acid under heating to produce a product, which is then washed with water, and water and dibutylamine are added thereto for further reaction to obtain a coumarin derivative represented by 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 mol of compound A-3.
The amount of dibutylamine used is preferably 1 to 3 mol, and more preferably 1.5 to 2 mol, per 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., and even more preferably 100 to 140° C., and the reaction time is usually about 1 to 12 hours, and 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., and even more preferably 20 to 30° C., and the reaction time is usually about 0.5 to 12 hours, and preferably about 1 to 4 hours.
The reaction atmosphere is not particularly limited, and may be either an air atmosphere or an inert gas atmosphere such as nitrogen gas.
After the reaction is completed, the reaction product is post-treated and purified in a conventional manner to obtain the coumarin derivative represented by formula (1A).

A specific example of the naphthophosphoroxide derivative is the naphthophosphoroxide derivative represented by the following formula (1B):

A specific example of the above pyrromethene derivative is the pyrromethene derivative represented by the following formula (1C):

A specific example of the perylene derivative is the perylene derivative represented by the following formula (1D):

Taking into account the wavelength conversion efficiency of the resulting wavelength conversion film, the content of the above (A) phosphor is preferably 0.1 to 10 mass% of the solid content, more preferably 0.2 to 7 mass%, and even more preferably 0.3 to 5 mass%.

The titanium oxide particles (B) are blended as light scattering particles. The titanium oxide particles are not particularly limited, and may be appropriately selected from those conventionally used in wavelength converting materials, for example.
It is generally known that blending light-scattering particles into a composition for forming a wavelength conversion film for displays extends the optical path length within the film of light that enters the wavelength conversion film, increasing the opportunities for wavelength conversion within the wavelength conversion film, thereby improving the wavelength conversion efficiency, and also that light that returns to the inside of the film due to reflection at the interface of the wavelength conversion film is scattered again, thereby improving the light extraction efficiency.

Either anatase or rutile type titanium oxide particles can be used, but considering the transmittance of ultraviolet light at 365 nm, rutile type titanium oxide is more preferred because it has a higher transmittance.

The titanium oxide particles used may be surface-treated, but in the present invention, taking into consideration the storage stability of the composition, it is preferable that the particles are not surface-treated.
In the case of carrying out the surface treatment, specific examples of the surface treatment material include different inorganic oxides such as silicon oxide and zirconium oxide, metal hydroxides such as aluminum hydroxide, organosiloxanes, organic acids such as stearic acid, etc. These surface treatment materials may be used alone or in combination of two or more kinds.

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

Commercially available titanium oxide particles may be used, and specific examples include, but are not limited to, PT-401M (rutile type, average particle diameter 70 nm), PT-401L (rutile type, average particle diameter 130 nm), and PT-501R (rutile type, average particle diameter 180 nm). Note that the average particle diameter of the titanium oxide particles exemplified may vary by ±10 nm.

Taking into consideration the wavelength conversion efficiency and storage stability, the content of the (B) titanium oxide particles is preferably 0.1 to 20 mass% of the solid content, more preferably 0.2 to 15 mass%, even more preferably 0.3 to 10 mass%, and even more preferably 3 to 10 mass%.

The above (C) binder may be selected from known resins, etc. that are used as binders in compositions for forming wavelength conversion films for displays.

The resin can be appropriately selected from resins used as base resins in compositions for forming wavelength conversion films for displays, and examples thereof include 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); and 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.
The above resins may be commercially available products or may be synthesized by a conventional method such as radical polymerization using a polymerization initiator.

The average molecular weight of the resin is not particularly limited, but the weight average molecular weight (Mw) is usually 5,000 to 100,000, and preferably 10,000 to 50,000.
The average molecular weight is a value calculated as polystyrene by gel permeation chromatography.

The binder (C) may be a mixture of a polymerizable monomer and a photopolymerization initiator, which may be polymerized after the film is formed. These may also be used in combination with the above-mentioned resin.
The polymerizable monomer is not particularly limited as long as it is used together with a photopolymerization initiator and polymerized by irradiation with light, but an ethylenically unsaturated monomer is preferred. In the present invention, the ethylenically unsaturated monomer may be any of a monofunctional monomer, a bifunctional monomer, and a trifunctional or higher monomer.

An example of a monofunctional monomer is a mono(meth)acrylate represented by the following formula (M1):

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 effect of improving external quantum efficiency, 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, for example, may have an ether bond.

Specific examples of monofunctional monomers 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, diethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethyl ... Examples of the acryloyloxyethyl (meth)acrylate include ethylaminoethyl (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, mono(2-acryloyloxyethyl) succinate, N-[2-(acryloyloxy)ethyl]phthalimide, and N-[2-(acryloyloxy)ethyl]tetrahydrophthalimide. Among these, ethoxyethoxyethyl (meth)acrylate is preferably used.

As the monofunctional monomer, 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 preferred because it is easy to improve the ejection stability in the inkjet method. In this 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.

An example of a bifunctional monomer is di(meth)acrylate represented by the following formula (M2):

In formula (M2), each of the multiple R ^m3 independently represents a hydrogen atom or a methyl group, and R ^m4 represents a divalent 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 effect of improving external quantum efficiency, the number of carbon atoms in the hydrocarbon group is preferably 7 or less. The hydrocarbon group may be substituted, for example, may have an ether bond.

Specific examples of bifunctional monomers 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 diacrylate, di(meth)acrylate in which two hydroxyl groups of tris(2-hydroxyethyl)isocyanurate are substituted with (meth)acryloyloxy groups, di(meth)acrylate in which two hydroxyl groups of diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of neopentyl glycol are substituted with (meth)acryloyloxy groups, bisphenol A Examples of such di(meth)acrylates include a diol obtained by adding 2 moles of ethylene oxide or propylene oxide to 1 mole of bisphenol A, in which two hydroxyl groups of the diol are substituted with (meth)acryloyloxy groups, a di(meth)acrylate obtained by adding 3 moles or more of ethylene oxide or propylene oxide to 1 mole of trimethylolpropane, in which two hydroxyl groups of the triol are substituted with (meth)acryloyloxy groups, and a di(meth)acrylate obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of bisphenol A, in which two hydroxyl groups of the diol are substituted with (meth)acryloyloxy groups. Among these, dipropylene glycol di(meth)acrylate is preferably used.

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 preferred because it is easy to improve the ejection stability in the inkjet method. The above viscosities are measured at 25°C.

An example of a trifunctional monomer is tri(meth)acrylate represented by the following formula (M3):

In formula (M3), each of the multiple R ^m5 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 effect of improving external quantum efficiency, the number of carbon atoms in the hydrocarbon group is preferably 4 or less. The hydrocarbon group may be substituted, for example, may have an ether bond.

Specific examples of trifunctional monomers include glycerin tri(meth)acrylate, trimethylolethane tri(meth)acrylate, etc. Among these, glycerin tri(meth)acrylate is preferably used.

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 preferred because it is easy to improve the ejection stability in the inkjet method. The above viscosities are measured at 25°C.

As the photopolymerization initiator, a photoradical polymerization initiator, a photocationic polymerization initiator, etc. can be used. In consideration of compatibility with general manufacturing methods for wavelength conversion members, it is preferable to use a photoradical polymerizable compound, and in terms of being able to form pixel portions (cured products of the ink composition) without being inhibited by oxygen in the curing process, it is preferable to use a photocationic polymerizable compound.

As the photoradical polymerization initiator, a molecular cleavage type or hydrogen abstraction type photoradical polymerization initiator is preferably used.

Examples of molecular cleavage type photoradical polymerization initiators include benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine 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, and (2,4,6-trimethylbenzoyl)ethoxyphenylphosphine oxide. Other molecular cleavage type photoradical polymerization initiators that may be used in combination include, 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, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one.

Examples of hydrogen abstraction type photoradical polymerization initiators include benzophenone, 4-phenylbenzophenone, isophthalphenone, and 4-benzoyl-4'-methyl-diphenyl sulfide. A molecular cleavage type photoradical polymerization initiator and a hydrogen abstraction type photoradical polymerization initiator may be used in combination.

Photoradical polymerization initiators are also available commercially. Examples of such commercially available products include acylphosphine oxide compounds such as Omnirad 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 compounds such as Omnirad MBF and "Omnirad 754"; and Irgacure (registered trademark, the same applies below) manufactured by BASF Japan Ltd. Examples of oxime ester compounds include OXE01, Irgacure OXE02, Irgacure OXE03, Irgacure OXE04, TR-PBG-304 and TR-PBG-305 manufactured by Changzhou Strong Electronic New Materials Co., Ltd., and NCI-831 and NCI-930 manufactured by ADEKA Corporation.

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

Examples of photocationic polymerization initiators include polyarylsulfonium salts such as triphenylsulfonium hexafluoroantimonate and triphenylsulfonium hexafluorophosphate; and polyaryliodonium salts such as diphenyliodonium hexafluoroantimonate and p-nonylphenyliodonium hexafluoroantimonate.

The photocationic polymerization initiator can also be obtained as a commercially available product. Examples of such commercially available products include sulfonium salt-based photocationic polymerization initiators such as CPI-100P manufactured by San-Apro Co., Ltd., Omnicat (registered trademark; the same applies below) 270 manufactured by IGM Resin, and Irgacure 290 manufactured by BASF Japan; and iodonium salt-based photocationic polymerization initiators such as Omnicat 250 manufactured by IGM Resin.

From the viewpoint of the curability of the composition, the content of the photopolymerization initiator is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass, relative to 100% by mass of the polymerizable monomer. 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.

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

Furthermore, the composition for forming a wavelength conversion film for a display of the present invention may contain, in addition to the above-mentioned components (A) to (C), 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, as necessary.
As the surfactant, a fluorine-based surfactant is preferable, and a nonionic fluorine-based surfactant is more preferable.
Specific examples thereof include the Ftergent series, 212M, 215M, 250, 222F, FTX-218, and DFX-18 manufactured by Neos Co., Ltd., but are not limited thereto.
When a surfactant is used, its blending amount is not particularly limited, but is preferably 0.01 to 1 mass %, more preferably 0.01 to 0.5 mass %, based on the solid content of the composition for forming a wavelength conversion film for a display.

Furthermore, the composition for forming a wavelength conversion film for a display of the present invention may contain a solvent as 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; ethyl acetate, normal hexyl acetate, ethyl lactate, γ-butyrolactone, and propylene carbonate. ester-based solvents such as diisopropyl malonate and diisopropyl malonate; halogenated hydrocarbon solvents such as methylene chloride, dichloromethane, 1,2-dichloroethane and chloroform; amide-based solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone; alcohol-based solvents such as methanol, ethanol, isopropanol, n-propanol, cyclohexanol, diacetone alcohol and 2-benzooxyethanol; ethylene glycol monoethyl ether and other Examples of the organic solvent include glycol ether solvents such as 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; and 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 may be used alone or in combination of two or more.

When the composition for forming a wavelength conversion film for displays contains a solvent, the solids concentration of the composition for forming a wavelength conversion film for displays cannot be generally specified because it varies depending on the desired thickness of the wavelength conversion film and the application method, etc., but is usually 10 to 70 mass %, and preferably 20 to 60 mass %.

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

The composition for forming a wavelength conversion film for a display of the present invention can be prepared by mixing the above-mentioned components (A) to (C), other additives such as a surfactant that are used as necessary, and a solvent in any order.

The above-mentioned composition for forming a wavelength conversion film for a display of the present invention can be applied, for example, onto a substrate, and if necessary, the solvent can be evaporated by heating or the like, and if necessary, the composition can be irradiated with active energy rays (for example, ultraviolet light) to obtain a wavelength conversion film.
Examples of the application method include methods using a reverse roll coater, blade coater, slit die coater, direct gravure coater, offset gravure coater, kiss coater, natural roll coater, air knife coater, roll blade coater, barrier roll blade coater, two-stream coater, rod coater, wire bar coater, applicator, dip coater, curtain coater, spin coater, knife coater, inkjet, etc.

Heating can be carried out 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 heating at 60 to 200° C. for 5 minutes to 2 hours is preferable, and heating at 80 to 200° C. for 15 minutes to 1 hour is more preferable. Heat curing may be carried out in stages.

The irradiation with ultraviolet light is not particularly limited as long as a film can be formed, but light sources such as mercury lamps, metal halide lamps, xenon lamps, LEDs, etc. can be used, and light from which light other than the desired exposure wavelength is removed can be irradiated by combining a bandpass filter as necessary. The wavelength of the irradiated light is preferably 200 to 440 nm, and particularly preferably contains light with a wavelength of 300 to 400 nm. The exposure dose is preferably 10 to 4,000 mJ/ ^cm2 .

The heating step and the ultraviolet light exposure step may be combined in any order. For example, heating may be performed before ultraviolet light irradiation, ultraviolet light irradiation may be performed before heating, or heating may be performed before ultraviolet light irradiation and then further heating may be performed.

The thickness of the wavelength converting film is not particularly limited, but is usually 1 to 1,000 μm, preferably 3 to 500 μm, and more preferably 5 to 100 μm.
The haze value of the wavelength conversion film is not particularly limited, but is preferably 18% or more, more preferably 30% or more, and more preferably 40% or more, from the viewpoint of increasing the amount of light that can be absorbed by the phosphor by scattering the incident light within the film. 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, the measurement conditions for the haze value include, for example, conditions for measuring a film having a thickness of 6 μm formed from a composition having a titanium oxide particle content of 3.16 to 4.74 mass %.

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

The wavelength conversion film obtained from the composition of the present invention has excellent wavelength conversion efficiency and can therefore 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, as well as lighting.

The present invention will be explained in more detail below with reference to synthesis examples, working examples and comparative examples, but the present invention is not limited to the following examples.

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

The meanings of the abbreviations used in the present examples are as follows: The chemical shifts of ^{the 1} H-NMR spectrum of Dye A are as follows: The measurement device used was AVANCE III HD 500 MHz (manufactured by Bruker).
¹ H NMR (in CDCl3): δ/ppm 8.93(1H,s), 8.41(1H,d,J=1.6Hz), 8.05(1H,d,J=8.5Hz), 7.87(1H,dd,J=1.6,8.5Hz), 7.48(1H,d,J=9.0Hz), 6.67(1H,dd,J=2.3,9.0Hz), 6.54(1H,d,J=2.3Hz), 3.40(2H,t,J=7.8Hz), 3.24(2H,d,J=7.0Hz), 3.17 (4H,t,J=7.6Hz), 1.76-1.62 (9H,m), 1.52(4H,qui,J=7.8Hz), 1.34-1.16(12H,m), 1.00(2H,q,J=11.1Hz), 0.92(3H,t,J=6.9Hz), 0.92(6H,t,J=7.4Hz)
MMA: methyl methacrylate MAA: methacrylic acid AIBN: α,α'-azobisisobutyronitrile V#230: Viscoat #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 size 50 nm, AlOH3 coating, manufactured by Ishihara Sangyo Kaisha, Ltd.)
PT-401M: Titanium oxide particles (rutile type, average particle size 70 nm, manufactured by Ishihara Sangyo Kaisha, Ltd.)
PT-401L: Titanium oxide particles (rutile type, average particle size 130 nm, manufactured by Ishihara Sangyo Kaisha, Ltd.)
PT-501R: Titanium oxide particles (rutile type, average particle size 180 nm, manufactured by Ishihara Sangyo Kaisha, Ltd.)
CR-EL: Titanium oxide particles (rutile type, average particle size 250 nm, manufactured by Ishihara Sangyo Kaisha, Ltd.)
Light scattering particles 1: titanium oxide particles (anatase type, average particle size 100 nm, SiO ₂ -SnO ₂ coating)
DFX-18: Futergent DFX-18 (manufactured by Neos Co., Ltd.)

Dye A: a compound represented by the following formula (1A)

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

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

Dye D: a compound represented by the following formula (1D), FL 305, manufactured by BASF

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 obtained acrylic polymer had an Mn of 9,900 and an Mw of 17,078.

[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% by mass tetraethylammonium hydroxide aqueous solution, 39.4 g of glycine, and 213.2 g of titanium tetraisopropoxide (containing 59.9 g in terms of _TiO2 ) were added under stirring. The resulting mixed solution had a molar ratio of tetraethylammonium hydroxide/titanium atom of 1.00 and a molar ratio of glycine/titanium atom of 0.70. The mixed solution was held at 90°C for 2 hours, and then held at 95°C for 5 hours to prepare a titanium mixed solution. The prepared titanium mixed solution had a pH of 11.2 and a _TiO2 concentration of 3.0% by mass. 1,500 g of the titanium mixed solution was placed in a 3-liter SUS autoclave container, and hydrothermal treatment was performed at 150°C for 5 hours. After cooling to room temperature, the solution taken out after hydrothermal treatment was a milky white aqueous dispersion of titanium oxide colloidal particles. The obtained dispersion had a pH of 12.2, a _TiO2 concentration of 3.0% by mass, and a dynamic light scattering particle size of 141 nm. Observation with a transmission electron microscope (JEM-F200, manufactured by JEOL Ltd.) revealed that the particles had a bale-like shape and an average primary particle size of 94 nm. The measurement device used for the dynamic light scattering method was a Zetasizer manufactured by Malvern Instruments Ltd.
The resulting aqueous dispersion of titanium oxide colloidal particles was then washed with water in an ultrafiltration device to remove excess electrolyte, yielding a dispersion with a _TiO2 concentration of 3.0% by mass. The resulting titanium oxide colloidal particles were used as core titanium oxide particles.

On the other hand, 27.9 g of an aqueous solution of sodium silicate (JIS No. 3 sodium silicate, containing 34% by mass as _SiO2 , manufactured by Fuji Chemical Co., Ltd.) was diluted with 27.9 g of pure water, and then 8.6 g of sodium stannate trihydrate (containing 55% by mass as _SnO2 , manufactured by Showa Kako Co., Ltd.) was added and dissolved under stirring to obtain an aqueous solution of silicate-sodium stannate. 64.4 g of the obtained aqueous solution of silicate-sodium stannate was diluted with 411 g of pure water and passed through a column filled with a hydrogen 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 alkaline aqueous dispersion of silicon dioxide-stannic oxide composite oxide colloidal particles, with a pH of 8.2 and a primary particle diameter of 5 nm or less. The obtained silicon dioxide-stannic oxide composite oxide colloidal particles were used as coated particles.

144.0 g of the prepared coated particles made of silicon dioxide-stannic oxide composite oxide was added to 1,200 g of the aqueous dispersion of titanium oxide particles serving as the cores, and the mixture was then kept at a temperature of 95°C for 2 hours to obtain an aqueous dispersion of modified titanium oxide colloidal particles. The aqueous dispersion of modified titanium oxide colloidal particles obtained was then passed through a column filled with a hydrogen cation exchange resin (Amberlite (registered trademark) IR-120B) to obtain an aqueous dispersion of acidic modified titanium oxide colloidal particles. The aqueous dispersion obtained was then placed in an evaporator equipped with an eggplant-shaped flask for concentration, and water was distilled off at 590 Torr while adding methanol to obtain 129.8 g of a methanol dispersion of modified titanium oxide colloidal particles. The obtained methanol dispersion had a viscosity of 1.2 mPa s, a pH of 6.4 (diluted with the same mass of water as the dispersion), a solids concentration of 30.5 mass%, a moisture content of 0.8 mass%, and a dynamic light scattering particle diameter of 140 nm. Observation with a transmission electron microscope revealed that the particles had a bale-like shape with an average primary particle diameter of 101 nm.

[Examples 1 to 10, Comparative Examples 1 to 9] Preparation of compositions for forming wavelength conversion films and evaluation thereof (1) Preparation of compositions for forming wavelength conversion films The components were mixed in the compositions 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 compositions for forming wavelength conversion films. The composition ratios in Tables 1 and 2 represent the mass ratios of the solid contents.

(2) Evaluation 1: Evaluation of Viscosity For the compositions for forming a wavelength conversion film of Examples 1 to 10 and Comparative Examples 1 to 9, measurements were carried out under the conditions shown below, and the measured values were regarded as the viscosity of each composition for forming a wavelength conversion film.
Apparatus: EMS-1000 manufactured by Kyoto Electronics Manufacturing Co., Ltd. Measurement temperature: 25°C
Probe size: 2.0 mm Φ
Rotational speed: 500 rpm
Measurement time: 5 seconds

(3) Evaluation 2: Evaluation of film properties The wavelength conversion film-forming compositions 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 prebaked on a hot plate at 110° C. for 120 seconds to obtain coating samples with a film thickness of 6 μm. Thereafter, the coating samples of Examples 1 to 6, and 9, and Comparative Examples 1, 2, 4 to 6, and 9 were postbaked at 160° C. for 60 minutes. The coating samples of Example 7 and Comparative Example 7 were postbaked at 120° C. for 60 minutes.
The wavelength conversion film-forming compositions of Example 8 and Comparative Examples 3 and 9 were applied onto an alkali-free glass substrate using a bar coater, and then the entire surface of the resin film was irradiated with ultraviolet light at 365 nm with an exposure dose of 1000 mJ/ ^cm2 using a batch-type UV irradiation device (high-pressure mercury lamp 2 kW x 1 lamp) (manufactured by Eye Graphics Co., Ltd.), thereby forming a cured film on the alkali-free glass substrate.
The haze value of the obtained coating film sample was measured using a turbidity meter NDH5000 manufactured by Nippon Denshoku Industries Co., Ltd. according to the measurement method in accordance with ASTM D1003-61.

Next, the coating sample was placed on top of 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 sample was measured using a spectroradiometer USR-45 manufactured by Ushio Inc., and the result was recorded as (1).
Similarly, the light emitted only from the LED light was measured, excluding the coating sample, and the result was (2). From the obtained spectral irradiance spectrum, the number of photons of light with a wavelength of 480 nm or less in result (2) was taken as the "number of excitation light photons". Similarly, the number of photons of light with a wavelength of 480 nm or less in result (1) was taken as the "number of transmitted light photons". Similarly, the number of photons of light with a wavelength of more than 480 nm in result (1) was taken as the "number of emitted light photons".
The "blue light absorptance" and "conversion efficiency" were calculated using the following formulas.
Blue light absorptance = (number of excitation light photons - number of transmitted light photons) ÷ number of excitation light photons Conversion efficiency = number of emitted photons ÷ number of excitation light photons

Further, the "conversion efficiency" of the coating samples of Examples 1 to 3, 9 and 10, and Comparative Example 4 divided by the "conversion efficiency" of the coating sample of Comparative Example 4, the "conversion efficiency" of the coating samples of Example 4 and Comparative Example 5 divided by the "conversion efficiency" of the coating sample of Comparative Example 5, the "conversion efficiency" of the coating samples of Example 5 and Comparative Example 6 divided by the "conversion efficiency" of the coating sample of Comparative Example 6, the "conversion efficiency" of the coating samples of Example 6 and Comparative Example 7 divided by the "conversion efficiency" of the coating sample of Comparative Example 7, the "conversion efficiency" of the coating samples of Example 7 and Comparative Example 8 divided by the "conversion efficiency" of the coating sample of Comparative Example 8, and the "conversion efficiency" of the coating samples of Example 8 and Comparative Example 9 divided by the "conversion efficiency" of the coating sample of Comparative Example 9 were defined as the "conversion efficiency enhancement degree". Based on the obtained conversion efficiency enhancement degree, the film properties of the coating samples were evaluated. The judgment criteria are as follows. The obtained results are shown in Tables 3 and 4.
<Judgment criteria>
A: Conversion efficiency increase is greater than 2.5 B: Conversion efficiency increase is greater than 2.1 and is equal to or less than 2.5 C: Conversion efficiency increase is equal to or less than 2.1

(4) Evaluation 3: Evaluation of film-formability In Evaluation 2, when the compositions for forming a wavelength conversion film 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 and the film-formability was evaluated. The judgment criteria were 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. In addition, the coating sample of Comparative Example 3 had radial coating unevenness on the film surface that was so noticeable that it was visible to the naked eye, and the film-forming property was extremely poor. Therefore, it was impossible to measure the "conversion efficiency" of Evaluation 2 for Comparative Example 3.

(5) Evaluation 4: Evaluation of storage stability The compositions for forming a wavelength conversion film 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 settling of titanium oxide particles) was visually confirmed. The evaluation criteria were as follows. The obtained results are shown in Tables 3 and 4.
<Judgment criteria>
A: No settling was observed within one week. B: No settling was observed after one day, but settling was observed after two days. C: Settling was observed after one day.

(6) Evaluation 5: Evaluation of total light reflectance For coating samples obtained in the same manner 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). The film properties of the coating samples were evaluated based on the total light reflectance obtained. The evaluation criteria were as follows. The obtained results are shown in Tables 3 and 4.
<Judgment criteria>
A: Total light reflectance is 15% or less. B: Total light reflectance is greater than 15%.

As shown in Tables 3 and 4, in Examples 1 to 10 which satisfy the requirements of the present invention, the degree of conversion efficiency increase in Evaluation 2 was high, and the storage stability in Evaluation 4 was good, and a balance between conversion efficiency and storage stability was observed. In contrast, in Comparative Examples 1 to 9 which do not satisfy the requirements of the present invention, the degree of conversion efficiency increase in Evaluation 2 was low, or the storage stability in Evaluation 4 was poor, and a balance between conversion efficiency and storage stability was not observed. Furthermore, Comparative Example 3 had a viscosity of 10,143 mPa·s, which does not satisfy the requirements of the present invention, and therefore the film-forming properties were extremely poor, making it difficult to evaluate the coating properties.

Claims (6)

(A) an organic dye, (B) titanium oxide particles, and (C) a binder;
The titanium oxide particles (B) may have a surface coated with an inorganic compound , and the titanium oxide particles have an average particle size of 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, the haze value of a film formed from the composition for forming a wavelength conversion film for a display being 18% or more. The composition for forming a wavelength conversion film for a display according to claim 1, wherein the average particle size of the titanium oxide particles (B) is greater than 100 nm and less than or equal to 190 nm. 3. The composition for forming a wavelength conversion film for a display according to claim 1 or 2, wherein the titanium oxide particles (B) are of rutile type and the surfaces of the titanium oxide particles are not coated. The composition for forming a wavelength conversion film for a display according to claim 1 or 2, wherein the content of the titanium oxide particles (B) is 3 to 10 mass % of the solid content. 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. A display equipped with the wavelength conversion film according to claim 5.