Color conversion sheet, and light source unit, display, and lighting device that include same

Abstract

This color conversion sheet converts incident light into light of a wavelength different from that of the incident light. The color conversion sheet has a light extraction layer as the outermost layer thereof, the surface roughness Ra of the light extraction layer is 0.05-2 μm, and the average value of the total reflectance in a wavelength region of 440-470 nm on at least one surface of the color conversion sheet is 10-60%. The present invention provides a color conversion sheet used for a display, a lighting device, etc., the color conversion sheet having a small angle dependence of color and has high brightness.

Description

Color conversion sheet, and light source unit, display, and lighting device including the same

[0001] The present invention relates to a color conversion sheet, and a light source unit, a display, and a lighting device that include the same.

[0002] There has been active research into applying multi-color technology using color conversion methods to liquid crystal displays, organic EL displays, lighting, etc. Color conversion refers to converting light from a light emitter into light with a longer wavelength, such as converting blue light into green or red light.

[0003] By forming this composition having color conversion function into a sheet and combining it with, for example, a blue light source, it becomes possible to obtain the three primary colors of blue, green, and red from the blue light source, thereby making it possible to obtain white light. By using a white light source combining such a blue light source with a sheet having color conversion function as a backlight unit and combining it with a liquid crystal driver and a color filter, it becomes possible to produce a full-color display. Furthermore, a white light source combining a blue light source with a sheet having color conversion function can also be used directly as a white light source for LED lighting, etc.

[0004] The challenges facing liquid crystal displays that use color conversion methods include the need to improve visibility and brightness. To address these challenges, a technology has been proposed in which an optical adjustment layer with predetermined reflective properties is provided on a color conversion layer, thereby improving color conversion efficiency and emitting uniform color light (see, for example, Patent Document 1).

[0005] JP 2016-62804 A

[0006] In Patent Document 1, the refractive index difference between the transparent resin and the dispersed particles in the wavelength conversion layer is reduced to enable the emitted concentrated light without diffusing. However, if the blue light source itself has uneven light distribution, i.e., if the light intensity varies greatly depending on the viewing angle, the light is emitted without being diffused, making it difficult to isotropically reflect the blue light. This results in a problem of significant color unevenness depending on the viewing angle on the viewing side, i.e., a high degree of color angular dependency. Furthermore, if the reflectivity of the wavelength conversion layer is increased to improve the uneven light distribution of such a blue light source, there is a problem that sufficient brightness cannot be ensured.

[0007] Therefore, an object of the present invention is to provide a color conversion sheet that can provide a display, lighting device, or the like with small angle dependency of color and high brightness.

[0008] In order to solve the above-mentioned problems and achieve the objects, the present invention has the following configurations. [1] A color conversion sheet that converts incident light into light with a different wavelength from the incident light, the color conversion sheet having a light extraction layer as its outermost layer, the light extraction layer having a surface roughness Ra of 0.05 μm to 2 μm, and at least one surface of the color conversion sheet having an average total reflectance of 10% to 60% in a wavelength range of 440 nm to 470 nm. [2] The color conversion sheet according to [1], wherein, when the average total reflectance of the first surface of the color conversion sheet in a wavelength range of 520 nm to 580 nm is Rg1 and the average total reflectance of the second surface of the color conversion sheet in a wavelength range of 520 nm to 580 nm is Rg2, 3%≦Rg1−Rg2 is satisfied. [3] The color conversion sheet according to [1] or [2], wherein Rb1 is the average total reflectance in the wavelength range of 440 nm to 470 nm on the first surface of the color conversion sheet, and Rb2 is the average total reflectance in the wavelength range of 440 nm to 470 nm on the second surface of the color conversion sheet, and 5%≦Rb2−Rb1≦13% is satisfied. [4] The color conversion sheet according to any one of [1] to [3], wherein the average total reflectance in the wavelength range of 440 nm to 470 nm on the color conversion sheet is 30% to 60%. [5] The color conversion sheet according to any one of [1] to [3], wherein the average total reflectance in the wavelength range of 440 nm to 470 nm on the color conversion sheet is 30% to 45%. [6] The color conversion sheet according to any one of [1] to [5], wherein the color conversion sheet contains scattering particles. [7] The content of the scattering particles is 0.03 g / m ２ ~2.1g / m ２The color conversion sheet according to [6], wherein the scattering particles comprise titania. [8] The color conversion sheet according to [6] or [7], wherein the scattering particles comprise titania. [9] The color conversion sheet according to any one of [1] to [8], wherein the color conversion sheet comprises at least a color conversion layer (A) and a color conversion layer (B), wherein the color conversion layer (A) contains a light-emitting material (a) that emits light having a peak wavelength observed in the range of 500 nm or more and less than 580 nm, and the color conversion layer (B) contains a light-emitting material (b) that emits light having a peak wavelength observed in the range of 580 nm or more and 750 nm or less.

[10] The color conversion sheet according to [9], wherein the light-emitting material (a) and / or the light-emitting material (b) are organic light-emitting materials.

[11] The color conversion sheet according to [9] or

[10] , wherein the organic light-emitting material (a) and / or the light-emitting material (b) contain a compound represented by general formula (1):

[0009]

[0010] X is C-R ７ or N; R １ ~R ９may be the same or different and are selected from hydrogen, alkyl groups, cycloalkyl groups, heterocyclic groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, hydroxyl groups, thiol groups, alkoxy groups, alkylthio groups, aryl ether groups, aryl thioether groups, aryl groups, heteroaryl groups, halogen atoms, cyano groups, aldehyde groups, carbonyl groups, carboxyl groups, oxycarbonyl groups, carbamoyl groups, amino groups, nitro groups, silyl groups, siloxanyl groups, boryl groups, phosphine oxide groups, and fused rings and aliphatic rings formed between adjacent substituents.

[12] The color conversion sheet according to any one of [9] to

[11] , wherein at least one of the color conversion layer (A) and the color conversion layer (B) contains scattering particles.

[13] A light source unit comprising a light source and the color conversion sheet according to any one of [1] to

[12] .

[14] The light source unit according to

[13] , wherein the light extraction layer of the color conversion sheet is disposed on the side opposite the light source.

[15] A light source unit including a light source and the color conversion sheet according to [3], wherein the color conversion sheet is arranged so that the second surface of the color conversion sheet faces the light source.

[16] The light source unit according to any one of

[13] to

[15] , wherein the light source is a light-emitting diode having a maximum emission in the range of 400 nm to 500 nm.

[17] A display including the light source unit according to any one of

[13] to

[16] .

[18] A lighting device including the light source unit according to any one of

[13] to

[16] .

[0011] The color conversion sheet according to the present invention has the effect of reducing the angle dependency of color and achieving high brightness. The light source unit, display, and lighting device according to the present invention use such a color conversion sheet, and therefore are able to reduce the angle dependency of color and achieve high brightness.

[0012] Schematic cross-sectional view showing an example of the color conversion sheet of the present invention. ... light source unit of the present invention.

[0013] The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified in various ways depending on the purpose and application.

[0014] <Color Conversion Sheet> The color conversion sheet according to the embodiment of the present invention is a sheet that converts incident light into light with a wavelength different from that of the incident light, preferably light with a wavelength longer than that of the incident light.

[0015] In order to reduce the angle dependence of color produced by a color conversion sheet, it is desirable to make the light emitted when the incident light passes through the color conversion sheet approach Lambertian radiation. Lambertian radiation here refers to radiation based on Lambert's law, which states that the intensity of light emitted from a perfectly diffusive surface is proportional to the cosine of the angle between the normal to the surface and the observation direction. Light produced by Lambertian radiation is said to appear the same from any angle.

[0016] When a color conversion sheet is used to convert incident light (e.g., blue light from a blue light source) into light of a different wavelength from the incident light (e.g., green light or red light), the light that is wavelength-converted and emitted within the color conversion sheet is radiated isotropically, whereas the incident light is unlikely to be isotropic because it is radiated from the light source.

[0017] The color conversion sheet according to the embodiment of the present invention has an average total reflectance of 10% to 60% on at least one surface in the wavelength range of 440 nm to 470 nm. This allows the incident blue light to be closer to Lambertian radiation. This reduces the angular dependence of blue and other colors wavelength-converted from it. From the viewpoint of achieving both brightness and angular dependence, the lower limit of the average total reflectance is preferably 30% or more. The upper limit of the average total reflectance is preferably 60% or less, and more preferably 45% or less.

[0018] In the color conversion sheet according to the embodiment of the present invention, the surface having an average total reflectance of 10% to 60% in the wavelength range of 440 nm to 470 nm is preferably the surface disposed on the light source side, because this allows the blue light incident on the color conversion sheet from the light source to be closer to Lambertian radiation at the time of incidence.

[0019] From the viewpoint of further improving brightness, the color conversion sheet according to the embodiment of the present invention preferably satisfies 3%≦Rg1−Rg2 in the wavelength range of 520 nm to 580 nm, where Rg1 is the average total reflectance of the first surface and Rg2 is the average total reflectance of the second surface. Here, when the average total reflectance of each surface of the color conversion sheet is measured in the wavelength range of 520 nm to 580 nm, the surface with the larger average total reflectance is referred to as the first surface, and the surface with the smaller average total reflectance is referred to as the second surface. Note that if the average total reflectances measured from both surfaces are equal, either surface may be designated the first surface. In such a case, for convenience, one of the surfaces is designated the first surface, and the opposite surface is designated the second surface.

[0020] When the color conversion sheet according to the embodiment of the present invention is applied to a display or lighting device, it is preferable to arrange the color conversion sheet so that the first surface faces the viewer and the second surface faces the light source. With this arrangement, the reflection of light in the green region on the viewer side is significantly greater than that on the light source side, improving the green luminous efficiency and achieving higher brightness.

[0021] There is no particular restriction on the upper limit of Rg1-Rg2, but from the viewpoint of achieving both high brightness and angle dependency of color, it is preferably 10% or less.

[0022] From the viewpoint of further reducing the angle dependence of color, the color conversion sheet according to the embodiment of the present invention preferably satisfies the following relationship: 5%≦Rb2−Rb1≦13% in the wavelength range of 440 nm to 470 nm, where Rb1 is the average total reflectance of the first surface and Rb2 is the average total reflectance of the second surface. When Rb2−Rb1 is 5% or more, the reflection of light in the blue region on the light source side is sufficiently greater than that on the viewing side, thereby enabling efficient reflection of light emitted from the blue light source, thereby further reducing the angle dependence of color. Furthermore, when Rb2−Rb1 is 13% or less, the light reflection on the second surface side falls within a moderate range, making it easier to achieve both angle dependence of color and high brightness.

[0023] The total reflectance of the color conversion sheet can be measured in accordance with ASTM E1164.

[0024] The color conversion sheet according to the embodiment of the present invention preferably comprises a light extraction layer, a color conversion layer, and a base layer. Each layer will be described in detail below.

[0025] Representative structural examples of the color conversion sheet according to the embodiment of the present invention include the following five examples.

[0026] 1 is a schematic cross-sectional view showing a first example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 1, this first example of a color conversion sheet 5A is a laminate of a light extraction layer 1, a base layer 2, and a color conversion layer 3. In this structural example of the color conversion sheet 5A, the color conversion layer 3 is laminated on the base layer 2.

[0027] 2 is a schematic cross-sectional view showing a second example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 2, this second example color conversion sheet 5B is a laminate of a plurality of light extraction layers 1A, 1B, a plurality of base layers 2A, 2B, and a color conversion layer 3. In this structural example of color conversion sheet 5B, the color conversion layer 3 is sandwiched between the two base layers 2A, 2B, and the light extraction layers 1A, 1B are the outermost layers.

[0028] 3 is a schematic cross-sectional view showing a third example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 3, this third example of a color conversion sheet 5C is a laminate of a plurality of light extraction layers 1A, 1B, a plurality of base layers 2A, 2B, a color conversion layer 3, and a plurality of barrier films 6A, 6B. In this structural example of color conversion sheet 5C, the color conversion layer 3 is sandwiched between two barrier films 6A, 6B, and this laminate is further sandwiched between two base layers 2A, 2B.

[0029] 4 is a schematic cross-sectional view showing a fourth example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 4, this fourth example of a color conversion sheet 5D is a laminate of a light extraction layer 1, a base layer 2, a color conversion layer (A) 3A, and a color conversion layer (B) 3B. In this structural example of the color conversion sheet 5D, the color conversion layer (B) 3B and the color conversion layer (A) 3A are laminated in this order on the base layer 2. The color conversion layer (A) and the color conversion layer (B) emit green and red light, respectively, and will be described in detail later. The lamination order of the color conversion layer (A) and the color conversion layer (B) may be reversed.

[0030] 5 is a schematic cross-sectional view showing a fifth example of a color conversion sheet according to an embodiment of the present invention. As shown in FIG. 5, this fifth example color conversion sheet 5E is a laminate of a plurality of light extraction layers 1A, 1B, a plurality of base layers 2A, 2B, a color conversion layer (A) 3A, and a color conversion layer (B) 3B. In this structural example of color conversion sheet 5E, the color conversion layer (A) 3A and the color conversion layer (B) 3B are sandwiched between the two base layers 2A, 2B, and the light extraction layers 1A, 1B are the outermost layers.

[0031] (Light Extraction Layer) The color conversion sheet according to an embodiment of the present invention has a light extraction layer as its outermost layer. The surface roughness Ra of the light extraction layer is 0.05 μm to 2 μm, more preferably 0.1 μm to 1.5 μm, and even more preferably 0.2 μm to 1 μm. When the surface roughness Ra of the light extraction layer is within the above range, light within the color conversion sheet can be efficiently reflected, thereby improving brightness. In order to improve brightness by reflecting more light toward the viewing side, it is preferable that the light extraction layer be arranged on the side opposite the light source.

[0032] The material for the light extraction layer is not particularly limited as long as it has a surface roughness Ra of 0.05 μm to 2 μm, but it is preferable that the material contains at least a binder resin and particles.

[0033] Known binder resins can be used, including thermosetting resins, thermoplastic resins, UV-curable resins, etc. Specific examples of the thermoplastic resin include Oricox (registered trademark) KC-7000 (acrylic resin, manufactured by Kyoeisha Chemical Co., Ltd.) and UV-curable resins include LUXYDIR (registered trademark) V-4221 (urethane acrylate, manufactured by DIC Corporation). These resins may be used alone or in combination of two or more.

[0034] Examples of the particles include organic and / or inorganic particles. Specific examples include particles composed of glass, titania, silica, alumina, silicone resin, zirconia, ceria, aluminum nitride, silicon carbide, silicon nitride, barium titanate, acrylic resin, etc. These may be used alone or in combination of two or more. From the viewpoint of availability, particles selected from silica particles, alumina particles, titania particles, zirconia particles, acrylic resin particles, silicone resin particles, etc. are preferred. Furthermore, from the viewpoint of improving brightness, it is preferred that the particles include at least either acrylic resin particles or silicone resin particles.

[0035] The average particle size of the particles is not particularly limited, but is preferably 100 nm to 10,000 nm, and more preferably 100 nm to 5,000 nm from the viewpoint of binder dispersibility and coating properties.

[0036] The thickness of the light extraction layer is not particularly limited, but is preferably 0.5 μm to 10 μm, and more preferably 1 μm to 5 μm from the viewpoint of coatability.

[0037] (Base Layer) The base layer has the function of supporting the color conversion layer.

[0038] The material for the substrate layer is not particularly limited, and known materials such as metals, films, glass, ceramics, and paper can be used. Specific examples include metal plates and metal foils made of aluminum (including aluminum alloys), zinc, copper, iron, etc.; plastic films made of cellulose acetate, polyethylene terephthalate (PET), polyethylene, polyester, polyamide, polyimide, polyphenylene sulfide, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, aramid, silicone, polyolefin, thermoplastic fluororesin, tetrafluoroethylene-ethylene copolymer (ETFE), α-polyolefin resin, polycaprolactone resin, acrylic resin, silicone resin, and copolymer resins of these with ethylene; paper laminated with the above-mentioned plastic films or paper coated with the above-mentioned plastics, paper laminated or vapor-deposited with the above-mentioned metals, and plastic films laminated or vapor-deposited with the above-mentioned metals. Furthermore, when the substrate is a metal plate, the surface may be plated with a chromium or nickel-based material or ceramic-treated.

[0039] Among these, glass and resin films are preferably used because of the ease of producing and molding the color conversion sheet. Furthermore, films with high strength are preferred so that there is no risk of breakage during handling of the substrate. Resin films are preferred in terms of the required properties and economic efficiency, and among these, plastic films made of a resin selected from the group consisting of PET, polyphenylene sulfide, polycarbonate, and polypropylene are preferred in terms of economic efficiency and handling efficiency.

[0040] The thickness of the substrate layer is not particularly limited, but the lower limit is preferably 5 μm or more, more preferably 25 μm or more, and even more preferably 38 μm or more, and the upper limit is preferably 5000 μm or less, and more preferably 3000 μm or less.

[0041] (Color Conversion Layer) The color conversion layer is a layer containing a light-emitting material that converts incident light into light of a different wavelength from the incident light, and a binder resin.

[0042] In the present invention, the color conversion sheet includes at least a color conversion layer (A) and a color conversion layer (B). The color conversion layer (A) preferably contains a light-emitting material (a) that emits light with a peak wavelength observed in the range of 500 nm to less than 580 nm, and the color conversion layer (B) preferably contains a light-emitting material (b) that emits light with a peak wavelength observed in the range of 580 nm to 750 nm. The light-emitting materials (a) and (b) are contained in different layers, which suppresses interaction between the materials, resulting in light emission with higher color purity than when they are dispersed in the same layer. Furthermore, suppressing interaction between the light-emitting materials (a) and (b) allows the light-emitting materials (a) and (b) to emit light independently in each layer, making it easier to adjust the green and red emission peak wavelengths and emission intensities.

[0043] That is, by using the color conversion sheet according to the present embodiment in combination with a blue light source, it is possible to design optimal emission peak wavelengths and emission intensities for each of blue, green, and red light without deteriorating the properties of light-emitting materials such as light-emitting material (a) and light-emitting material (b) that emit light with high color purity, thereby obtaining white light with good color purity and higher brightness.

[0044] (Light-emitting material) Examples of the light-emitting material used in the present invention include inorganic fluorescent materials, fluorescent pigments, fluorescent dyes, quantum dots, etc. Two or more of these may be contained. In order to achieve highly efficient color conversion, a material exhibiting light-emitting properties with a high quantum yield is preferred, quantum dots or organic light-emitting materials are more preferred, and organic light-emitting materials are particularly preferred.

[0045] When the color conversion sheet includes the color conversion layer (A) and the color conversion layer (B), it is preferable that the light-emitting material (a) and / or the light-emitting material (b) is an organic light-emitting material.

[0046] Examples of organic light-emitting materials include compounds having a fused aryl ring, such as naphthalene, anthracene, phenanthrene, pyrene, chrysene, naphthacene, triphenylene, perylene, fluoranthene, fluorene, and 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, and pyrrolopyridine, and derivatives thereof; borane derivatives; 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; coumarin derivatives such as coumarin 6, coumarin 7, and coumarin 153; 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 Suitable examples include organometallic complex compounds containing metals such as iridium (Ir), ruthenium (Ru), rhodium (Rh), palladium (Pd), platinum (Pt), osmium (Os), and rhenium (Re).

[0047] The organic light-emitting material may be a fluorescent material or a phosphorescent material, but in order to achieve high color purity, a fluorescent material is preferred.

[0048] Among them, pyrromethene derivatives are preferably used because they provide a high fluorescence quantum yield and have better durability of chromaticity. More preferably, the compound represented by general formula (1) is used.

[0049]

[0050] X is C-R ７ Or N. １ ~R ９ may be the same or different and are selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring or an aliphatic ring formed between adjacent substituents.

[0051] In all of the above groups, hydrogen may be replaced with deuterium. The same applies to the compounds or partial structures thereof described below.

[0052] In the following description, for example, a substituted or unsubstituted aryl group having 6 to 40 carbon atoms means 6 to 40 carbon atoms including the number of carbon atoms contained in substituents substituted on the aryl group, and the same applies to other substituents specifying the number of carbon atoms.

[0053] In addition, in all of the above groups, the substituent when substituted is preferably a group selected from alkyl groups, cycloalkyl groups, heterocyclic groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, hydroxyl groups, thiol groups, alkoxy groups, alkylthio groups, aryl ether groups, aryl thioether groups, aryl groups, heteroaryl groups, halogen, cyano groups, aldehyde groups, carbonyl groups, carboxyl groups, oxycarbonyl groups, carbamoyl groups, amino groups, nitro groups, silyl groups, siloxanyl groups, boryl groups and phosphine oxide groups, and more preferably a specific substituent that is preferred in the description of each substituent.In addition, these substituents may be further substituted with the above-mentioned substituents.

[0054] The term "unsubstituted" in the context of "substituted or unsubstituted" means that a hydrogen atom or a deuterium atom has been substituted. The same applies to the term "substituted or unsubstituted" in the compounds or partial structures thereof described below.

[0055] The alkyl group refers to a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group, which may or may not have a substituent. When the alkyl group is substituted, the additional substituent is not particularly limited, and examples thereof include an alkyl group, a halogen atom, an aryl group, and a heteroaryl group. This point is also applicable to the following description. Furthermore, the number of carbon atoms in the alkyl group is not particularly limited, but is preferably in the range of 1 to 20, more preferably 1 to 8, in terms of availability and cost.

[0056] The cycloalkyl group refers to a saturated alicyclic hydrocarbon group, such as a cyclopropyl group, a cyclohexyl group, a norbornyl group, an adamantyl group, or the like, which may or may not have a substituent. The number of carbon atoms in the alkyl group is not particularly limited, but is preferably in the range of 3 to 20.

[0057] The heterocyclic group refers to an aliphatic ring having atoms other than carbon atoms in the ring, such as a pyran ring, a piperidine ring, or a cyclic amide, which may or may not have a substituent. The number of carbon atoms in the heterocyclic group is not particularly limited, but is preferably in the range of 2 to 20.

[0058] The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond, such as a vinyl group, an allyl group, or a butadienyl group, which may or may not have a substituent. The number of carbon atoms in the alkenyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0059] The cycloalkenyl group refers to an unsaturated alicyclic hydrocarbon group containing a double bond, such as a cyclopentenyl group, a cyclopentadienyl group, or a cyclohexenyl group, which may or may not have a substituent. The number of carbon atoms in the cycloalkenyl group is not particularly limited, but is preferably in the range of 3 to 20.

[0060] The alkynyl group refers to an unsaturated aliphatic hydrocarbon group containing a triple bond, such as an ethynyl group, which may or may not have a substituent. The number of carbon atoms in the alkynyl group is not particularly limited, but is preferably in the range of 2 to 20.

[0061] The alkoxy group refers to a functional group in which an aliphatic hydrocarbon group is bonded via an ether bond, such as a methoxy group, an ethoxy group, or a propoxy group, and this aliphatic hydrocarbon group may or may not have a substituent. The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably in the range of 1 to 20.

[0062] An alkylthio group is an alkoxy group in which the oxygen atom of the ether bond is replaced with a sulfur atom. The hydrocarbon group of the alkylthio group may or may not have a substituent. The number of carbon atoms in the alkylthio group is not particularly limited, but is preferably in the range of 1 to 20.

[0063] The aryl ether group refers to a functional group to which an aromatic hydrocarbon group, such as a phenoxy group, is bonded via an ether bond, and the aromatic hydrocarbon group may or may not have a substituent. The number of carbon atoms in the aryl ether group is not particularly limited, but is preferably in the range of 6 to 40.

[0064] An aryl thioether group is an aryl ether group in which the oxygen atom of the ether bond is substituted with a sulfur atom. The aromatic hydrocarbon group in the aryl ether group may or may not have a substituent. The number of carbon atoms in the aryl ether group is not particularly limited, but is preferably in the range of 6 to 40.

[0065] The aryl group refers to an aromatic hydrocarbon group such as a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a benzofluorenyl group, a dibenzofluorenyl group, a phenanthryl group, an anthracenyl group, a benzophenanthryl group, a benzanthracenyl group, a chrysenyl group, a pyrenyl group, a fluoranthenyl group, a triphenylenyl group, a benzofluoranthenyl group, a dibenzoanthracenyl group, a perylenyl group, or a helicenyl group. Among these, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, an anthracenyl group, a pyrenyl group, a fluoranthenyl group, or a triphenylenyl group is preferred. The aryl group may or may not have a substituent. The number of carbon atoms in the aryl group is not particularly limited, but is preferably 6 to 40, more preferably 6 to 30.

[0066] R １ ~R ９ When is a substituted or unsubstituted aryl group, the aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, or an anthracenyl group, more preferably a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, even more preferably a phenyl group, a biphenyl group, or a terphenyl group, and particularly preferably a phenyl group.

[0067] When each of the substituents is further substituted with an aryl group, the aryl group is preferably a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, or an anthracenyl group, more preferably a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group, and particularly preferably a phenyl group.

[0068] The heteroaryl group refers to a cyclic aromatic group having one or more atoms other than carbon in the ring, such as a pyridyl group, a furanyl group, a thiophenyl group, a quinolinyl group, an isoquinolinyl group, a pyrazinyl group, a pyrimidyl group, a pyridazinyl group, a triazinyl group, a naphthyridinyl group, a cinnolinyl group, a phthalazinyl group, a quinoxalinyl group, a quinazolinyl group, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, a benzocarbazolyl group, a carbolinyl group, an indolocarbazolyl group, a benzofurocarbazolyl group, a benzothienocarbazolyl group, a dihydroindenocarbazolyl group, a benzoquinolinyl group, an acridinyl group, a dibenzoacridinyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group. Here, the naphthyridinyl group refers to any of a 1,5-naphthyridinyl group, a 1,6-naphthyridinyl group, a 1,7-naphthyridinyl group, a 1,8-naphthyridinyl group, a 2,6-naphthyridinyl group, and a 2,7-naphthyridinyl group. The heteroaryl group may or may not have a substituent. The number of carbon atoms in the heteroaryl group is not particularly limited, but is preferably in the range of 2 to 40, more preferably 2 to 30.

[0069] R １ ~R ９When is a substituted or unsubstituted heteroaryl group, the heteroaryl group is preferably a pyridyl group, a furanyl group, a thiophenyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group, more preferably a pyridyl group, a furanyl group, a thiophenyl group, or a quinolinyl group, and particularly preferably a pyridyl group.

[0070] When each substituent is further substituted with a heteroaryl group, the heteroaryl group is preferably a pyridyl group, a furanyl group, a thiophenyl group, a quinolinyl group, a pyrimidyl group, a triazinyl group, a benzofuranyl group, a benzothiophenyl group, an indolyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a carbazolyl group, a benzimidazolyl group, an imidazopyridyl group, a benzoxazolyl group, a benzothiazolyl group, or a phenanthrolinyl group, more preferably a pyridyl group, a furanyl group, a thiophenyl group, or a quinolinyl group, and particularly preferably a pyridyl group.

[0071] Halogen refers to an atom selected from fluorine, chlorine, bromine and iodine.

[0072] The carbonyl group, carboxyl group, oxycarbonyl group, and carbamoyl group may or may not have a substituent. Examples of the substituent include an alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group, and these substituents may be further substituted.

[0073] The amino group is a substituted or unsubstituted amino group. In the case of substitution, examples of the substituent include an aryl group, a heteroaryl group, a linear alkyl group, and a branched alkyl group. As the aryl group and the heteroaryl group, a phenyl group, a naphthyl group, a pyridyl group, and a quinolinyl group are preferred. These substituents may be further substituted. The number of carbon atoms is not particularly limited, but is preferably in the range of 2 to 50, more preferably 6 to 40, and particularly preferably 6 to 30.

[0074] The silyl group refers to, for example, alkylsilyl groups such as trimethylsilyl, triethylsilyl, tert-butyldimethylsilyl, propyldimethylsilyl, and vinyldimethylsilyl, and arylsilyl groups such as phenyldimethylsilyl, tert-butyldiphenylsilyl, triphenylsilyl, and trinaphthylsilyl. The substituent on the silicon may be further substituted. The number of carbon atoms in the silyl group is not particularly limited, but is preferably in the range of 1 to 30.

[0075] The siloxanyl group refers to a silicon compound group bonded via an ether bond, such as a trimethylsiloxanyl group, etc. The substituent on the silicon may be further substituted.

[0076] The boryl group is a substituted or unsubstituted boryl group. When substituted, examples of the substituent include an aryl group, a heteroaryl group, a linear alkyl group, a branched alkyl group, an aryl ether group, an alkoxy group, and a hydroxyl group, and among these, an aryl group and an aryl ether group are preferred.

[0077] The phosphine oxide group is —P(═O)R １０ R １１ R is a group represented by the formula: １０ , R １１ is the R １ ~R ９ are selected from the same group.

[0078] In addition, any two adjacent substituents (for example, R １ and R ２ ) may be bonded to each other to form a conjugated or non-conjugated fused ring. The fused ring may contain, in addition to carbon, an element selected from nitrogen, oxygen, sulfur, phosphorus, and silicon. Furthermore, the fused ring may be further fused with another ring.

[0079] When the compound represented by general formula (1) is used as a light-emitting material, it exhibits a high fluorescence quantum yield and has a small half-width peak of the emission spectrum, and therefore, it is possible to achieve efficient color conversion and high color purity, and further improve the durability of chromaticity.

[0080] Also, R７ As the alkyl group, a structure represented by the following general formula (2) is preferred.

[0081]

[0082] r is selected from the group consisting of hydrogen, alkyl groups, cycloalkyl groups, heterocyclic groups, alkenyl groups, cycloalkenyl groups, alkynyl groups, hydroxyl groups, thiol groups, alkoxy groups, alkylthio groups, aryl ether groups, aryl thioether groups, aryl groups, heteroaryl groups, halogens, cyano groups, aldehyde groups, carbonyl groups, carboxyl groups, oxycarbonyl groups, carbamoyl groups, amino groups, nitro groups, silyl groups, siloxanyl groups, boryl groups, and phosphine oxide groups. k is an integer of 1 to 3. When k is 2 or greater, each r may be the same or different.

[0083] Preferably, r is a substituted or unsubstituted aryl group. Among aryl groups, phenyl and naphthyl groups are particularly preferred. When r is an aryl group, k in general formula (2) is preferably 1 or 2, and from the viewpoint of obtaining a high fluorescence quantum yield, k is more preferably 2. Furthermore, it is preferable that at least one of r is substituted with an alkyl group or an aryl group. In this case, particularly preferred examples of the alkyl group include a group selected from a methyl group, an ethyl group, and a tert-butyl group. Furthermore, when r is an aryl group, a group selected from a phenyl group and a naphthyl group is preferred, and these aryl groups may be further substituted with an alkyl group, a heterocyclic group, an alkenyl group, a hydroxyl group, an alkoxy group, an aryl ether group, an aryl group, a heteroaryl group, a halogen atom, a cyano group, a carboxyl group, an ester group, an oxycarbonyl group, or an alkoxy group.

[0084] Examples of the compound represented by formula (1) are shown below, but the compound is not limited to these.

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092] The compound represented by general formula (1) can be produced by the methods described in, for example, JP-A-8-509471 and JP-A-2000-208262, in which a pyrromethene compound is reacted with a metal salt in the presence of a base to obtain the desired pyrromethene metal complex.

[0093] Furthermore, the pyrromethene-boron fluoride complex can be synthesized by referring to the methods described in J. Org. Chem., vol. 64, No. 21, pp. 7813-7819 (1999), Angew. Chem., Int. Ed. Engl., vol. 36, pp. 1333-1335 (1997), etc. For example, a method in which a compound represented by the following general formula (3) and a compound represented by the following general formula (4) are heated in 1,2-dichloroethane in the presence of phosphorus oxychloride, and then a compound represented by the following general formula (5) is reacted in 1,2-dichloroethane in the presence of triethylamine, can be mentioned, but is not limited thereto. １ ~R ９ is the same as above. J represents a halogen.

[0094]

[0095] Furthermore, when introducing an aryl group or a heteroaryl group, a method of forming a carbon-carbon bond using a coupling reaction between a halogenated derivative and a boronic acid or a boronate ester derivative can be used, but this is not a limitation. Similarly, when introducing an amino group or a carbazolyl group, a method of forming a carbon-nitrogen bond using a coupling reaction between a halogenated derivative and an amine or a carbazole derivative in the presence of a metal catalyst such as palladium can be used, but this is not a limitation.

[0096] The color conversion layer of the present invention may contain an assist dopant such as rubrene in order to increase the efficiency of energy transfer from the excitation light to the compound that emits delayed fluorescence.

[0097] Examples of organic light-emitting materials other than the compound represented by general formula (1) are shown below, but the present invention is not particularly limited to these.

[0098]

[0099] Examples of inorganic phosphors include SrAl ２ O ４ : Eu, Y ２ SiO ５ :Ce, Tb, MgAl １１ O １９ : Ce, Tb, Sr ７ Al １２ O ２５ : Eu, MgGa ２ S ４ : Eu, CaGa ２ S ４ : Eu, SrGa ２ S ４ : Eu, BaGa ２ S ４ : Green phosphor such as Eu; ５ (P.O. ４ ) ３ Cl:Eu, (SrCaBa) ５ (P.O. ４ ) ３ Cl:Eu, (BaCa) ５ (P.O. ４ ) ３ Cl:Eu, B ５ O ９ Cl: Eu, Mn, Mg (PO ４ ) ６ Cl ２ :Eu, Mn, Ca(PO ４ ) ６ Cl ２ :Eu, Mn, Sr(PO ４ ) ６ Cl ２ :Eu, Mn, Ba(PO ４ ) ６ Cl ２ : Blue phosphors such as Eu and Mn; ２ O ２S: Eu, La ２ O ２ S: Eu, Y ２ O ３ : Eu, Gd ２ O ２ S: Eu, K ２ SiF ６ There are also red phosphors such as Y:Mn. ３ (Al, Ga) ５ O １２ :Ce, (Y, Gd) ３ Al ５ O １２ : Ce, Lu ３ Al ５ O １２ : Ce, Y ３ Al ５ O １２ : YAG-based phosphor such as Ce, Tb ３ Al ５ O １２ : TAG-based phosphors such as Ce, (Ba, Sr) ２ SiO ４ : Eu-based phosphor or Ca ３ Sc ２ Si ３ O １２ : Ce-based phosphor, (Sr, Ba, Mg) ２ SiO ４ : Silicate-based phosphors such as Eu, (Ca, Sr) ２ Si ５ N ８ :Eu, (Ca,Sr)AlSiN ３ :Eu, CaSiAlN ３ : Nitride phosphor such as Eu, Cax(Si,Al) １２ (O, N) １６ :Eu and other oxynitride phosphors, and further (Ba, Sr, Ca)Si ２ O ２ N ２ : Eu-based phosphor, Ca ８ MgSi ４ O １６ Cl ２ : Eu-based phosphor, SrAl ２ O ４ : Eu, Sr4Al １４ O ２５ :Eu and other phosphors.

[0100] Quantum dots are phosphors with excellent quantum efficiency, and by confining electrons, holes, and excitons in all directions in three-dimensional space in nano-sized (for example, diameters of about 2 nm to 10 nm) semiconductor crystals, they have discrete energy levels, and by changing the size of the dots, the peak wavelength (emission color) of the emitted light can be freely selected. Materials used for quantum dots include materials combining Zn, Cd, Pb, etc., which can be divalent cations, with O, S, Se, Te, etc., which can be divalent anions (for example, cadmium selenide (CdSe), zinc sulfide (ZnS), etc.), materials combining Ga, In, etc., which can be trivalent cations, with P, As, Sb, etc., which can be trivalent anions (for example, indium phosphide (InP), gallium arsenide (GaAs), etc.), and even chalcopyrite-type compounds (CuInSe ２ A preferred example of the material for the quantum dot phosphor is CdSe.

[0101] Compounds that emit delayed fluorescence are discussed on pages 87-103 of "State-of-the-Art Organic EL" (edited by Adachi Chinaya and Fujimoto Hiroshi, published by CMC Publishing). This document explains that by bringing the energy levels of the singlet excited state and triplet excited state of an emitting material close to each other, reverse energy transfer from the triplet excited state, which normally has a low transition probability, to the singlet excited state occurs with high efficiency, resulting in the manifestation of thermally activated delayed fluorescence (TADF). Furthermore, Figure 5 in this document explains the mechanism by which delayed fluorescence occurs. The emission of delayed fluorescence can be confirmed by transient photoluminescence (PL) measurements.

[0102] In this specification, a compound that emits fluorescence by transitioning from a triplet excited state to a singlet excited state with high efficiency, including a compound that exhibits thermally activated delayed fluorescence, is referred to as a "compound that emits delayed fluorescence."

[0103] Usually, fluorescent light is emitted from a singlet excited state generated after photoexcitation of a light-emitting material, and the triplet excited state of a light-emitting material generated by intersystem crossing is thermally deactivated in a room temperature environment and does not emit fluorescence. On the other hand, as described above, in a compound that emits delayed fluorescence, even if a triplet excited state is generated, it is quickly converted to a singlet excited state and then emits fluorescence. Therefore, the triplet excited state, which cannot contribute to light emission in ordinary fluorescent materials, can also contribute to fluorescent light emission. Therefore, highly efficient light emission can be obtained.

[0104] The triplet excited state of a compound that emits delayed fluorescence quickly converts to a singlet excited state, making it difficult to generate singlet oxygen. This feature has been found to prevent degradation of the luminescent material, suppress changes in chromaticity over time, and improve durability.

[0105] In order to design a molecule so that the energy levels of the singlet excited state and the triplet excited state are close to each other, it is effective to bond an electron donor skeleton and an electron acceptor skeleton within the same molecule. By doing so, it is possible to separate the HOMO (highest occupied molecular orbital) orbital and the LUMO (lowest unoccupied molecular orbital) orbital within the molecule. The electron donor skeleton and the electron acceptor skeleton may be bonded directly or via a linking group. In this case, the linking group is preferably a skeleton containing an aromatic hydrocarbon.

[0106] Examples of electron donor skeletons include skeletons having an amine nitrogen atom. Among them, skeletons selected from skeletons containing diarylamine or triarylamine, skeletons containing carbazole, skeletons containing benzocarbazole, skeletons containing indolocarbazole, skeletons containing phenoxazine, and skeletons containing phenothiazine are preferred. Among these, skeletons selected from skeletons containing carbazole, skeletons containing benzocarbazole, skeletons containing indolocarbazole, and skeletons containing phenoxazine are more preferred, and skeletons selected from skeletons containing carbazole and skeletons containing phenoxazine are even more preferred.

[0107] On the other hand, examples of electron-accepting skeletons include skeletons containing electron-withdrawing substituents. Electron-withdrawing groups, also called electron-accepting groups, are atomic groups that attract electrons from substituted atomic groups due to inductive effects or resonance effects in organic electronics theory. Examples of electron-withdrawing groups include those whose Hammett's rule substituent constant (σp(para)) is a positive value. The Hammett's rule substituent constant (σp(para)) can be cited from the Revised 5th Edition of the Basic Chemistry Handbook (II-380 pages).

[0108] Although there are cases where a phenyl group also takes a positive value, the phenyl group is not included in the electron-withdrawing groups of the present application.

[0109] Examples of the electron-withdrawing group include -F (σp: +0.20), -Cl (σp: +0.28), -Br (σp: +0.30), -I (σp: +0.30), and -CO ２ R １２ (σp:R １２ is an ethyl group, +0.45), -CONH ２ (σp: +0.38), -COR １２ (σp:R １２ is a methyl group, +0.49), -CF ３ (σp: +0.51), -SO ２ R １２ (σp:R １２ is a methyl group, +0.69), -NO ２ (σp: +0.81) and the like. １２represents a hydrogen atom, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 ring carbon atoms, a substituted or unsubstituted heterocyclic group having 5 to 30 ring atoms, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 1 to 30 carbon atoms. Specific examples of each of these groups include the same examples as above.

[0110] Among these, preferred are skeletons containing a heteroaryl group having a partial structure in which a carbon atom and a nitrogen atom are bonded by a double bond, skeletons containing a fluorinated substituent, skeletons containing a cyano group, skeletons containing a carbonyl group, skeletons containing a sulfoxide or disulfoxide, and skeletons containing a phosphine oxide group. Among these, skeletons containing a heteroaryl group having a partial structure in which a carbon atom and a nitrogen atom are bonded by a double bond, skeletons containing a fluorinated substituent, and skeletons containing a cyano group are more preferred from the viewpoint of the stability of the compound.

[0111] Among skeletons containing a heteroaryl group having a partial structure in which a carbon atom and a nitrogen atom are bonded by a double bond, specifically, skeletons containing pyridine, pyrimidine, pyrazine, triazine, quinoline, quinoxaline, quinazoline, or phenanthroline are preferred, and among these, skeletons containing pyrimidine, triazine, quinoxaline, or quinazoline are more preferred, and skeletons containing triazine are even more preferred.

[0112] Among the skeletons containing fluorinated substituents, skeletons containing fluorinated aryl groups or fluoroalkyl groups are more preferred.As the skeletons containing fluorinated aryl groups, fluorinated benzene rings are preferred, and specifically, skeletons containing fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene or pentafluorobenzene are more preferred.As the skeletons containing fluoroalkyl groups, skeletons containing benzene rings substituted with trifluoromethyl groups are preferred, and among these, skeletons containing mono(trifluoromethyl)benzene or bis(trifluoromethyl)benzene are more preferred.

[0113] Among the skeletons having a cyano group, skeletons containing cyanobenzene, dicyanobenzene, and tricyanobenzene are more preferred.

[0114] Examples of compounds in which the above-described electron donor skeleton and electron acceptor skeleton are combined are shown below, but are not limited to these. Note that the compounds shown here are known to emit delayed fluorescence according to previous literature.

[0115]

[0116] In addition to the compounds having the above-mentioned electron donor skeleton and electron acceptor skeleton bonded together, compounds represented by general formula (6) or (7) are also preferred as compounds that emit delayed fluorescence.

[0117]

[0118] In general formula (6) or (7), ring Za, ring Zb, and ring Zc each independently represent a substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms, or a substituted or unsubstituted heteroaryl ring having 6 to 30 ring carbon atoms.

[0119] Z １ and Z ２ are each independently an oxygen atom, NRa (a nitrogen atom having a substituent Ra), or a sulfur atom. １ When R is NRa, R may be bonded to ring Za or ring Zb to form a ring. ２ When is NRa, Ra may be bonded to ring Za or ring Zc to form a ring.

[0120] E is a boron atom, a phosphorus atom, SiRa (a silicon atom having a substituent Ra), or P═O. １ and E ２ each independently represents BRa (a boron atom having a substituent Ra), PRa (a phosphorus atom having a substituent Ra), SiRa ２ (a silicon atom having two substituents Ra), P(=O)Ra ２ (phosphine oxide having two substituents Ra), P(=S)Ra ２ (phosphine sulfide having two substituents Ra), S(=O) or S(=O) ２ It is. １ is BRa, PRa, SiRa２ , P(=O)Ra ２ or P(=S)Ra ２ When R a is R a , R a may be bonded to ring Z a or ring Z b to form a ring. ２ is BRa, PRa, SiRa ２ , P(=O)Ra ２ or P(=S)Ra ２ In the case where R a is a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a substituted or unsubstituted alkyl group, R a may be bonded to ring Z a or ring Z c to form a ring.

[0121] Examples of the substituted or unsubstituted aryl ring having 6 to 30 ring carbon atoms in ring Za, ring Zb, and ring Zc include aromatic hydrocarbon rings such as a benzene ring, a naphthalene ring, a phenanthrene ring, a chrysene ring, an anthracene ring, and a pyrene ring. Among these, a benzene ring is preferred from the viewpoint of ensuring solubility. Examples of heteroaryl rings having 5 to 30 ring carbon atoms include aromatic heteroaryl ring structures such as a pyridine ring, a quinoline ring, and a phenanthroline ring. From the viewpoints of ease of raw material availability and difficulty of synthesis, a pyridine ring is preferred.

[0122] Ra is preferably a group having 6 to 40 carbon atoms including the substituent. Ra is more preferably a substituted or unsubstituted aryl group. Examples of the substituted or unsubstituted aryl group include a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted naphthyl group, and a substituted or unsubstituted phenanthrenyl group. A substituted or unsubstituted phenyl group is more preferred.

[0123] Rb is preferably a group having 6 to 40 carbon atoms including the substituent, and more preferably a substituted or unsubstituted aryl group or a substituted or unsubstituted alkyl group.

[0124] Z １ and Z ２is preferably an oxygen atom or NRa, because the π-conjugated system of the compound represented by general formula (6) or (7) is efficiently expanded, and reverse intersystem crossing from the triplet excited state to the singlet excited state occurs more efficiently, thereby further improving durability.

[0125] E is preferably a boron atom, and E １ and E ２ is preferably BRa, because the π-conjugated system of the compound represented by general formula (6) or (7) is efficiently expanded, and reverse intersystem crossing from the triplet excited state to the singlet excited state occurs more efficiently, thereby further improving durability.

[0126] Ring Za, ring Zb, and ring Zc are preferably benzene rings, because the π-conjugated system of the compound represented by general formula (7) or (7) is efficiently expanded, and reverse intersystem crossing from the triplet excited state to the singlet excited state occurs more efficiently, thereby further improving durability.

[0127] The compound represented by general formula (6) or (7) is a molecule that can separate the HOMO orbital and the LUMO orbital by the multiple resonance effect by optimally arranging an electron-donating amine nitrogen atom and an electron-accepting boron atom, as described in, for example, the literature Adv. Mater., 2016, 28, 2777-2781. From the viewpoint of clearly separating the HOMO orbital and the LUMO orbital, bringing the singlet excited state and the triplet excited state closer to each other and facilitating the emission of delayed fluorescence, it is preferable that E is a boron atom with strong electron-accepting properties and Z １ and Z ２ are preferably both NRa groups having strong electron donating properties.

[0128] Furthermore, due to the multiple resonance effect, the compound represented by general formula (6) or (7) has a sharper emission spectrum than a compound having an electron donor skeleton and an electron acceptor skeleton bonded thereto, resulting in emission of higher color purity. That is, the compound represented by general formula (6) or (7) is advantageous for improving the color gamut of the display, and is therefore preferred. Furthermore, in the compound represented by general formula (6) or (7), rings Za, Zb, and Zc are present around the E atom in general formula (6) or (7), where the LUMO orbital is mainly localized, and therefore the LUMO orbital can be delocalized from the E atom to each ring. By delocalizing the LUMO orbital, the multiple resonance effect operates efficiently, resulting in emission of higher color purity.

[0129] Furthermore, a structure in which Ra in the general formula (6) or (7) is bonded to at least one of the rings Za, Zb, and Zc is more preferred. This is because Ra is bonded to at least one of the rings Za, Zb, and Zc, and thus E in the general formula (6) or E in the general formula (7) is bonded to at least one of the rings Za, Zb, and Zc. １ and E ２ This is because it is expected that the steric protection effect of the compound will be further enhanced, and the effect of suppressing a decrease in the fluorescence quantum yield will be further improved.

[0130] Examples of the compounds represented by general formula (6) or (7) are shown below, but the compounds are not particularly limited to these.

[0131]

[0132] (Scattering Particles) From the viewpoint of achieving efficient and uniform color conversion, the color conversion sheet preferably contains scattering particles. The scattering particles are more preferably contained in the color conversion layer. Examples of scattering particles include organic and / or inorganic particles.

[0133] Specific examples include particles composed of glass, titania, silica, alumina, silicone resin, zirconia, ceria, aluminum nitride, silicon carbide, silicon nitride, barium titanate, acrylic resin, etc. These may be used alone or in combination of two or more. From the viewpoint of availability, particles selected from silica particles, alumina particles, titania particles, zirconia particles, acrylic resin particles, silicone resin particles, etc. are preferred. From the viewpoint of dispersibility in the binder resin in the color conversion layer, titania particles are more preferred. Furthermore, from the viewpoint of improving brightness, it is preferred that the scattering particles include particles selected from alumina particles, silica particles, and silicone resin particles.

[0134] The average particle size of the scattering particles is not particularly limited, but is preferably 100 nm to 5000 nm, and more preferably 100 nm to 500 nm. By using scattering particles with an average particle size in this range, the dispersibility in the binder resin is improved, and the light scattering efficiency of the luminescent material is improved.

[0135] The content of the scattering particles is not particularly limited, but is preferably 0.03 g / m ２ ~2.1 g / m ２ is preferable, and more preferably 0.9 g / m ２ ~2.1 g / m ２ is preferred, and 0.9 g / m ２ ~1.4g / m ２ By setting the content of the scattering particles in this range, it is possible to efficiently increase the reflectance in the color conversion layer while also achieving a good balance with the brightness. ２ ] is the color conversion layer 1m ２ When the color conversion sheet includes a color conversion layer (A) and a color conversion layer (B), it is preferable that the content of scattering particles in either one of the layers or both layers is in the above range.

[0136] Furthermore, in the present invention, when the color conversion sheet includes a color conversion layer (A) and a color conversion layer (B), it is preferable that at least one of the color conversion layer (A) and the color conversion layer (B) contains scattering particles. The scattering particles are preferably contained in a biased state in either the color conversion layer (A) or the color conversion layer (B). Here, "biased presence of scattering particles" means that only one of the color conversion layer (A) and the color conversion layer (B) contains scattering particles, or that the content of scattering particles in the color conversion layer (A) and the color conversion layer (B) is different. When the color conversion layer (A) contains scattering particles, the luminous efficiency of the (A) layer is improved, and the peak wavelength is shortened, resulting in a color conversion sheet with a wider color gamut. Furthermore, when the color conversion layer (B) contains scattering particles, the color conversion efficiency of the (B) layer is improved, and self-absorption is suppressed, thereby shortening the peak wavelength. When the peak wavelength of the color conversion layer (B) is shortened, it is possible to bring the luminous efficiency closer to the luminosity peak, resulting in a color conversion sheet with higher brightness.

[0137] Therefore, from the viewpoint of a high color gamut, it is preferable that the content of scattering particles in the color conversion layer (A) is greater than the content of scattering particles in the color conversion layer (B), and it is most preferable that only the color conversion layer (A) contains scattering particles. On the other hand, from the viewpoint of high brightness, it is preferable that the content of scattering particles in the color conversion layer (B) is greater than the content of scattering particles in the color conversion layer (A), and it is most preferable that only the color conversion layer (B) contains scattering particles.

[0138] When the above-mentioned pyrromethene derivatives or compounds represented by general formulas (6) and (7) are used as the luminescent material contained in the color conversion layer, these compounds tend to have strong self-absorption due to their small Stokes shift, which significantly increases the luminance and wide color gamut due to the bias of scattering particles.

[0139] (Binder Resin) The binder resin contained in the color conversion layer forms a continuous phase and may be a material having excellent moldability, transparency, heat resistance, etc. Examples of binder resins include photocurable resist materials having reactive vinyl groups, such as acrylic acid-based, methacrylic acid-based, polyvinyl cinnamate-based, and cyclic rubber-based materials, epoxy resins, silicone resins (including organopolysiloxane cured products (crosslinked products) such as silicone rubber and silicone gel), urea resins, fluorine resins, polycarbonate resins, acrylic resins, urethane resins, melamine resins, polyvinyl resins, polyamide resins, phenolic resins, polyvinyl alcohol resins, cellulose resins, aliphatic ester resins, aromatic ester resins, aliphatic polyolefin resins, and aromatic polyolefin resins. Copolymer resins of these may also be used as the binder resin. By appropriately designing these resins, binder resins useful for the color conversion composition and color conversion sheet according to the present invention can be obtained. Among these resins, epoxy resins, silicone resins, acrylic resins, ester resins, olefin resins, or mixtures thereof can be preferably used from the viewpoints of transparency, heat resistance, etc. Furthermore, from the viewpoint of durability, resins selected from acrylic resins, ester resins, and cycloolefin resins are more preferred.

[0140] Suitable specific examples of binder resins include those described in WO 2016 / 190283, WO 2017 / 61337, WO 2018 / 43237, WO 2019 / 21813, and WO 2019 / 188019.

[0141] The binder resin may contain additives such as dispersants and leveling agents for stabilizing the coating film, or may contain adhesion promoters such as silane coupling agents as sheet surface modifiers. The binder resin may also contain inorganic particles such as silica particles and silicone microparticles as agents for inhibiting the precipitation of color conversion materials.

[0142] (Other Additives) In addition to the binder resin and the luminescent material, the color conversion layer may contain fillers, antioxidants, processing and heat stabilizers, light resistance stabilizers such as ultraviolet absorbers, dispersants and leveling agents for stabilizing the coating film, plasticizers, crosslinking agents such as epoxy compounds, curing agents such as amines, acid anhydrides, and imidazoles, pigments, and adhesion aids such as silane coupling agents as modifiers for the sheet surface.

[0143] Examples of fillers include, but are not limited to, fine particles such as fumed silica, glass powder, and quartz powder, titanium oxide, zirconia oxide, barium titanate, zinc oxide, and silicone fine particles. These fillers may be used alone or in combination.

[0144] Examples of the antioxidant include, but are not limited to, phenolic antioxidants such as 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-ethylphenol. These antioxidants may be used alone or in combination.

[0145] Examples of processing and heat stabilizers include, but are not limited to, phosphorus-based stabilizers such as tributyl phosphite, tricyclohexyl phosphite, triethyl phosphine, diphenylbutyl phosphine, etc. These stabilizers may be used alone or in combination.

[0146] Examples of the light resistance stabilizer include, but are not limited to, benzotriazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole and 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole. These light resistance stabilizers may be used alone or in combination.

[0147] The content of these additives in the color conversion layer depends on the molar absorption coefficient, fluorescence quantum yield, and absorption intensity at the excitation wavelength of the compound, as well as the thickness and transmittance of the sheet to be produced, but is usually 1.0 × 10 －３Parts by mass or more and 30 parts by mass or less are preferred, and 1.0 × 10 －２ It is more preferable that the content is 1.0×10 parts by mass or more and 15 parts by mass or less. －１ It is particularly preferable that the amount is from 1 part by mass to 10 parts by mass.

[0148] (Solvent) The color conversion layer may contain a solvent. The solvent is not particularly limited as long as it can adjust the viscosity of the resin in a fluid state and does not excessively affect the light emission and durability of the light-emitting material. Examples of solvents include water, 2-propanol, ethanol, toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, hexane, heptane, acetone, methyl acetate, ethyl acetate, butyl acetate, propyl acetate, isopropyl acetate, terpineol, Texanol, methyl cellosolve, ethyl cellosolve, butyl carbitol, butyl carbitol acetate, 1-methoxy-2-propanol, propylene glycol monomethyl ether acetate, tetrahydrofuran, tetrahydropyran, and 1,4-dioxane. Two or more of these solvents may also be mixed and used. Among these solvents, toluene and ethyl acetate are particularly preferred because they do not affect the deterioration of the compound represented by general formula (1) and leave little residual solvent after drying.

[0149] (Barrier Layer) The color conversion sheet according to the embodiment of the present invention may further include a barrier layer. The barrier layer may be used as appropriate to prevent deterioration of the color conversion layer due to oxygen, moisture, or heat. The barrier layer is preferably provided so as to be in contact with the color conversion layer. The barrier layer may be provided on both sides of the color conversion layer, or on only one side.

[0150] Specific examples of the barrier layer include inorganic oxides such as silicon oxide, aluminum oxide, titanium oxide, tantalum oxide, zinc oxide, tin oxide, indium oxide, yttrium oxide, and magnesium oxide, inorganic nitrides such as silicon nitride, aluminum nitride, titanium nitride, and silicon carbonitride, mixtures thereof, metal oxide thin films or metal nitride thin films obtained by adding other elements to these, and films made of various resins such as polyvinylidene chloride, acrylic resins, silicone resins, melamine resins, urethane resins, fluorine-containing resins, and polyvinyl alcohol-based resins such as saponified vinyl acetate. Furthermore, examples of films having a moisture barrier function include films made of various resins such as polyethylene, polypropylene, nylon, polyvinylidene chloride, copolymers of vinylidene chloride and vinyl chloride, copolymers of vinylidene chloride and acrylonitrile, fluorine-containing resins, and polyvinyl alcohol-based resins such as saponified vinyl acetate.

[0151] (Other Layers) Furthermore, the color conversion sheet according to the embodiment of the present invention may further include an auxiliary layer having functions such as light extraction, anti-reflection, anti-glare, anti-reflection and anti-glare, hard coating (friction resistance), anti-static, anti-fouling, electromagnetic wave shielding, infrared blocking, ultraviolet blocking, polarization, color toning, etc. Furthermore, an adhesive layer may be provided between multiple color conversion layers.

[0152] The thickness of the color conversion sheet is not particularly limited, but is preferably 1 to 5,000 μm in total for all layers. A thickness of 1 μm or more ensures sufficient film strength, making it less likely for problems such as film breakage to occur. A thickness of 5,000 μm or less allows for a sheet with excellent handleability to be obtained. The thickness is more preferably 10 to 1,000 μm, even more preferably 15 to 500 μm, and particularly preferably 30 to 300 μm.

[0153] The film thickness of the color conversion sheet in the present invention refers to the film thickness (average film thickness) measured based on Method A of measuring thickness by mechanical scanning in JIS K7130 (1999) Plastics - Films and Sheets - Thickness Measurement Methods.

[0154] <Method for Producing Color Conversion Sheet> An example of a method for producing a color conversion sheet according to an embodiment of the present invention is described below. In this method for producing a color conversion sheet, first, a composition for producing a color conversion layer is prepared as follows. The above-mentioned light-emitting material, binder resin, solvent, and the like are mixed in predetermined amounts. After mixing the above components to a predetermined composition, the components are mixed and dispersed uniformly using a stirrer / kneader such as a homogenizer, a planetary mixer, a three-roller mixer, a ball mill, a planetary ball mill, or a bead mill, to obtain a color conversion composition. After mixing and dispersing, or during the mixing and dispersing process, degassing is preferably performed under vacuum or reduced pressure conditions. It is also possible to premix certain components, or to perform treatments such as aging. It is also possible to remove the solvent using an evaporator to achieve a desired solids concentration.

[0155] Next, the color conversion composition prepared by the above-mentioned method is applied to a substrate and dried. The substrate here is preferably a substrate film in which the above-mentioned substrate layer and light extraction layer are integrated. The application can be carried out 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, two-stream coater, rod coater, wire bar coater, applicator, dip coater, curtain coater, spin coater, knife coater, etc. In order to obtain a uniform thickness of the color conversion layer, application using a slit die coater or dip coater is preferred.

[0156] The color conversion layer can be dried using a common heating device such as a hot air dryer or an infrared dryer. In this case, the heating conditions are usually 40 to 250°C for 1 minute to 5 hours, and more preferably 60 to 200°C for 2 minutes to 4 hours. It is also possible to heat and cure the layer in stages using a step cure method or the like.

[0157] After the color conversion layer is formed, the substrate can be replaced as needed by simple methods such as, but not limited to, a method of replacing the substrate using a hot plate, or a method using a vacuum laminator or a dry film laminator.

[0158] <Light Source Unit> The light source unit according to the embodiment of the present invention includes at least a light source and a color conversion sheet. The light source included in the light source unit of the present invention can be any type of light source that emits light in a wavelength range that can be absorbed by the light-emitting material. For example, any light source, such as a hot cathode tube, a cold cathode tube, a fluorescent light source such as an inorganic EL, an organic electroluminescent element, a light-emitting diode (LED), or an incandescent light source, can be used in principle, but LEDs are particularly suitable. For light source units used in displays and lighting devices, a blue LED with a maximum emission wavelength in the 400-500 nm range is a suitable light source because it can enhance the color purity of blue light. Excitation light in the 400-500 nm wavelength range is also preferred because it has relatively low excitation energy and can prevent decomposition of the light-emitting material. The excitation light may have one emission peak or two or more emission peaks, but a single emission peak is preferred to enhance color purity. It is also possible to use multiple excitation light sources with different emission peaks in any combination.

[0159] By combining a blue light source with the color conversion sheet of the present invention, it becomes possible to obtain white light from the blue light source, and the color conversion sheet can be used as a light source unit that emits white light.

[0160] Although there are no particular limitations on the arrangement of the light source and the color conversion sheet, it is preferable that the light extraction layer of the color conversion sheet is arranged on the side opposite to the light source. Also, it is preferable that the color conversion sheet is arranged so that the second side of the color conversion sheet faces the light source, which allows more blue light from the light source to be reflected, thereby reducing the angle dependency of the color.

[0161] When the color conversion sheet includes color conversion layer (A) and color conversion layer (B), it is preferable that color conversion layer (B) is disposed closer to the light source than color conversion layer (A).

[0162] The light source unit may include other optical sheets in addition to the light source and the color conversion sheet. Examples of other optical sheets include a prism sheet, a polarizing reflective film, and a diffusion sheet. A typical configuration, as shown in FIG. 6 , includes a substrate 7, a reflective layer 8, and a light source 9 stacked together, a color conversion sheet 5 according to an embodiment of the present invention disposed between a diffusion plate 10 and a prism sheet 11, and a polarizing reflective film 12 disposed on the surface of the prism sheet 11 opposite the light source. Other configurations include a configuration in which the light source and the color conversion sheet are closely attached to each other, or a remote phosphor type in which the light source and the color conversion sheet are separated from each other. The light source unit may also include a color filter to enhance color purity.

[0163] The light source unit of the present invention can be used for applications such as backlight units for displays, lighting devices, interiors, signs, billboards, etc. It is particularly suitable for use in displays and lighting devices.

[0164] <Display and Illumination Device> A display and an illumination device according to an embodiment of the present invention include at least the light source unit described above.

[0165] Examples of displays include organic EL displays and liquid crystal displays. One example of an organic EL display configuration is a configuration in which an EL element that emits blue light with a maximum emission in the wavelength range of 400 to 500 nm is used as a light source, and the sheet of the present invention is placed on top of it to form a light source unit that emits white light, and this is combined with a color filter to provide a full-color display. One example of a liquid crystal display configuration is a configuration in which the above-mentioned light source unit is used as a backlight unit, and optical films such as a liquid crystal cell equipped with a color filter, a polarizing film, and a brightness enhancement film are further included.

[0166] The lighting device may use the light source unit of the present invention as is, or may further include a diffusion plate or a heat sink in addition to the light source unit of the present invention, or may further include a color filter for adjusting the color temperature.

[0167] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0168] <Measurement of Surface Roughness Ra> The surface roughness Ra of the light extraction layer was measured using a Surfcom 1400G (manufactured by Tokyo Seimitsu Co., Ltd.) in accordance with JIS B 0601 (2013). Each measurement was performed once.

[0169] <Measurement of Total Reflectance> The total reflectance of the color conversion sheets produced in the Examples and Comparative Examples was measured in accordance with ASTM E1164 using a spectrophotometer CM-2600D (manufactured by Konica Minolta, Inc.) as SCI (Specular Component Include). The average value of the total reflectance in the measurement wavelength range of 440 to 470 nm and the average value of the total reflectance in the measurement wavelength range of 520 to 580 nm were calculated. Each measurement was performed once.

[0170] <Evaluation of Color Angle Dependence> A BenQ LCD monitor (SW2700PT) was disassembled, and the color conversion sheets produced in the Examples and Comparative Examples described below were inserted in place of the built-in color conversion sheet. The monitor was then reassembled. The backlight unit was configured as "reflective film / light guide plate / color conversion sheet / diffusion sheet / prism sheet / polarized reflective film." The resulting monitor displayed blue, green, and red monochromatic colors, and their respective color coordinates in the (x, y) color space were measured using a spectroradiometer (CS-1000, manufactured by Konica Minolta). The spectroradiometer was positioned perpendicular to the center point of the monitor. The differences between the x and y values ​​measured with the monitor positioned perpendicular to the center and the x and y values ​​measured with the monitor tilted 30 degrees vertically were calculated as Δx and Δy, respectively. The measurement distance between the monitor and the spectroradiometer was 50 cm. If Δx and Δy are 0.015 or less, the angle dependency of color is small and the color conversion sheet is good, if they are 0.01 or less it is even better, and if they are 0.005 or less it is extremely good.

[0171] <Relative Brightness> As in the evaluation of the angle dependency of color, a BenQ LCD monitor (SW2700PT) was disassembled, and the color conversion sheets produced in the Examples and Comparative Examples described below were inserted in place of the built-in color conversion sheet. After that, the monitor was reassembled and the brightness was measured using a spectroradiometer (CS-1000, manufactured by Konica Minolta). The brightness of the white light after color conversion in Example 1 was set to 100, and the brightness of the Examples and Comparative Examples described below was compared. The relative brightness (%) is the brightness relative to Example 1 as the reference.

[0172] <Light-emitting material> In the following examples and comparative examples, compounds G-1 and R-1 are the compounds shown below.

[0173]

[0174] Compound G-1 (emission peak wavelength: 515 nm) was synthesized by a known method. Compound R-1 (emission peak wavelength: 629.5 nm) was synthesized by a known method.

[0175] <Substrate Film> Substrate film A: "Lumirror" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 100 μm) was used.

[0176] Substrate film B: 100 parts by weight of LUXYDIR (registered trademark) V-4221 (urethane acrylate, manufactured by DIC Corporation) as a resin, 0.15 parts by weight of MX-80H3WT (crosslinked acrylic monodisperse particles, average particle size 0.8 μm, manufactured by Soken Chemical & Engineering Co., Ltd.) as fine particles, and 25 parts by weight of toluene as a solvent were mixed, and then the mixture was stirred and degassed at 1000 rpm for 20 minutes using a planetary stirring and degassing apparatus "Mazerustar" (registered trademark) KK-400 (manufactured by Kurabo Industries, Ltd.) to obtain a composition for forming a light extraction layer.

[0177] Next, the composition for forming the light extraction layer was applied onto a substrate layer, "Lumirror" (registered trademark) U48 (manufactured by Toray Industries, Inc., thickness 100 μm), using a slit die coater, and the coating was dried by heating at 80° C. for 20 minutes. Thereafter, a high-pressure mercury lamp was used to dry the coating with an integrated light intensity of 250 mJ / cm. ２ The composition for forming a light extraction layer was cured by irradiating it with ultraviolet light of 1000 W at ...

[0178] Substrate film C: Substrate film C was obtained in the same manner as for substrate film B, except that the fine particles were changed to MX-300 (crosslinked acrylic monodisperse particles, average particle size 3 μm, manufactured by Soken Chemical & Engineering Co., Ltd.).

[0179] Substrate film D: Substrate film D was obtained in the same manner as in the preparation of substrate film B, except that the fine particles were changed to MX-500L (crosslinked acrylic monodisperse particles, average particle size 5 μm, manufactured by Soken Chemical & Engineering Co., Ltd.).

[0180] Substrate film E: Substrate film E was obtained in the same manner as in the preparation of substrate film B, except that the fine particles were changed to MX-1000 (crosslinked acrylic monodisperse particles, average particle size 10 μm, manufactured by Soken Chemical & Engineering Co., Ltd.).

[0181] Example 1 100 parts by weight of Oricox (registered trademark) KC-7000 (acrylic resin, manufactured by Kyoeisha Chemical Co., Ltd.) as a resin, 0.2 parts by weight of G-1 and 0.02 parts by weight of R-1 as luminescent materials, 3.3 parts by weight of JR-405 (titania particles, average particle size 0.21 μm, manufactured by Teika Corporation) as scattering particles, and 300 parts by weight of toluene as a solvent were mixed, and then the mixture was stirred and defoamed at 1000 rpm for 20 minutes using a planetary stirring and defoaming device "Mazerustar" (registered trademark) KK-400 (manufactured by Kurabo Industries, Ltd.) to obtain a resin composition for forming a color conversion layer.

[0182] Similarly, using "CLARITY" (registered trademark) LA2140 (acrylic resin, manufactured by Kuraray Co., Ltd.) as the resin, 160 parts by weight of toluene as the solvent was mixed with 100 parts by weight of the resin, and then the mixture was stirred and degassed for 20 minutes at 300 rpm using a planetary stirring and degassing device "MAZELSTAR" (registered trademark) KK-400 (manufactured by Kuraray Co., Ltd.) to obtain a resin composition for adhesive layer.

[0183] Next, a resin composition for forming a color conversion layer was applied to the surface of the base film C opposite the light extraction layer using a slit die coater, and heated and dried at 120°C for 20 minutes to form a color conversion layer with an average thickness of 25 μm.

[0184] Next, the resin composition for the adhesive layer was applied to the side opposite the light extraction layer of another substrate film C using a slit die coater, and heated and dried at 120°C for 20 minutes to form an adhesive layer with an average film thickness of 10 μm.

[0185] Next, the above two units were heat-laminated so that the color conversion layer and the adhesive layer were directly laminated to produce a color conversion sheet with a structure of "light extraction layer / base layer / color conversion layer / adhesive layer / base layer / light extraction layer."

[0186] The total reflectance, color angle dependency, and luminance of each of the two surfaces of the prepared color conversion sheet were measured using the methods described above. The results are shown in Table 1. Measurements were performed with an arbitrary surface facing the light source and the opposite surface facing the viewer. However, since the color conversion sheet of this example has a symmetrical structure, the values ​​measured from both surfaces were the same, as shown in Table 1.

[0187] (Examples 2 to 6, Comparative Examples 1 to 4) Color conversion sheets were produced and evaluated in the same manner as in Example 1, except that the type of substrate film and the amount of scattering particles added to the color conversion layer were changed as shown in Table 1. The results are shown in Table 1.

[0188] Comparing Example 1 and Comparative Example 1, the average total reflectance in the wavelength range of 440 nm to 470 nm was lower than 10%, and Example 1, in which the average total reflectance was 10% or more, showed significantly smaller angular dependency of color.

[0189] Furthermore, a comparison of Examples 1 to 4 revealed that the greater the average value of the total reflectance, the smaller the angle dependency of color. However, as shown in Comparative Example 2, when the average value of the total reflectance exceeds 60%, the angle dependency of color decreases, but the brightness is significantly reduced. Examples 1 and 2 were particularly good in terms of the balance between the angle dependency of color and brightness.

[0190] Comparing Example 1 and Comparative Example 3, Example 1, in which the surface roughness of the light extraction layer is 0.05 μm or more, exhibited significantly better brightness than Comparative Example 3, in which the surface roughness of the light extraction layer was less than 0.05 μm.

[0191] Furthermore, a comparison of Examples 1, 5, and 6 with Comparative Example 4 revealed that when the surface roughness of the light extraction layer was in the range of 0.05 μm to 2 μm, the brightness was good.

[0192]

[0193] Example 7 A resin composition (A) for producing a color conversion layer was obtained in the same manner as in Example 1, except that R-1 was not added.

[0194] A resin composition (B) for producing a color conversion layer was obtained in the same manner as in Example 1, except that G-1 was not added.

[0195] A resin composition for adhesive layer was obtained in the same manner as in Example 1.

[0196] Next, using a slit die coater, resin composition (A) for forming a color conversion layer was applied to the surface of base film C opposite the light extraction layer, and heated at 120°C for 20 minutes and dried to form a color conversion layer (A) with an average film thickness of 25 μm.

[0197] Next, using a slit die coater, resin composition (B) for forming a color conversion layer was applied to the side opposite the light extraction layer of another substrate film C, and heated and dried at 120°C for 20 minutes to form a color conversion layer (B) with an average film thickness of 25 μm.

[0198] Similarly, the adhesive resin composition was applied onto the color conversion layer (B) using a slit die coater, heated at 120° C. for 20 minutes, and dried to form an adhesive layer having an average thickness of 10 μm.

[0199] Next, the above two units were heat-laminated so that the color conversion layer (A) and the adhesive layer were directly laminated to produce a color conversion sheet with a structure of "light extraction layer / base layer / color conversion layer (A) / adhesive layer / color conversion layer (B) / base layer / light extraction layer."

[0200] Using the prepared color conversion sheet, the total reflectance of each of both surfaces was measured using the method described above. Because the surface on the color conversion layer (A) side had a higher average total reflectance in the wavelength range of 520 nm to 580 nm than the surface on the color conversion layer (B) side, the surface on the color conversion layer (A) side was designated the first surface, and the surface on the color conversion layer (B) side was designated the second surface. The angle dependence of color and luminance were measured using the method described above. Rb1 and Rg1 are the average values ​​of total reflectance measured from the surface on the color conversion layer (A) side (first surface), and Rb2 and Rg2 are the average values ​​of total reflectance measured from the surface on the color conversion layer (B) side (second surface). The angle dependence of color and luminance were measured by positioning the color conversion sheet so that the color conversion layer (B) side faced the light source.

[0201] Examples 8 to 11, Comparative Examples 5 to 6 Color conversion sheets were prepared and evaluated in the same manner as in Example 7, except that the amount of scattering particles added was changed as shown in Table 2. The results are shown in Table 2.

[0202] A comparison of Examples 7, 9, and 10 reveals that the larger the Rb2-Rb1, the smaller the angle dependency of color.

[0203] Comparing Example 7 and Example 11, it was found that the luminance was improved when the scattering particles were present only in the color conversion layer (B).

[0204]

[0205] (Example 12) A color conversion sheet was prepared in the same manner as in Example 7, and evaluated in the same manner as in Example 7, except that the measurement arrangement was changed so that the surface on the color conversion layer (B) side (second surface) became the viewing side. The results are shown in Table 3.

[0206] Comparing Example 7 and Example 12, it was found that the color angle dependence was smaller in Example 7, in which the color conversion layer (B) (second surface) was placed on the light source side, compared to Example 12, in which the color conversion layer (B) (second surface) was placed on the viewing side.

[0207]

[0208] REFERENCE SIGNS LIST 1, 1A, 1B Light extraction layer 2, 2A, 2B Base layer 3 Color conversion layer 3A Color conversion layer (A) 3B Color conversion layer (B) 5, 5A, 5B, 5C, 5D, 5E Color conversion sheet 6A, 6B Barrier layer 7 Substrate 8 Reflective layer 9 Light source 10 Diffuser 11 Prism sheet 12 Polarized reflective film 13 Light source unit

Claims

1. A color conversion sheet that converts incident light into light with a different wavelength from the incident light, said color conversion sheet having a light extraction layer as its outermost layer, said light extraction layer having a surface roughness Ra of 0.05 μm to 2 μm, and at least one surface of said color conversion sheet having an average total reflectance of 10% to 60% in the wavelength range of 440 nm to 470 nm.

2. The color conversion sheet according to claim 1, wherein Rg1 is an average value of the total reflectance in the wavelength region of 520 nm to 580 nm on the first surface of the color conversion sheet, and Rg2 is an average value of the total reflectance in the wavelength region of 520 nm to 580 nm on the second surface of the color conversion sheet, and 3%≦Rg1-Rg2 is satisfied.

3. The color conversion sheet according to claim 1, wherein, when the average value of the total reflectance in the wavelength region of 440 nm to 470 nm on the first surface of the color conversion sheet is Rb1 and the average value of the total reflectance in the wavelength region of 440 nm to 470 nm on the second surface of the color conversion sheet is Rb2, 5%≦Rb2-Rb1≦13%.

4. The color conversion sheet according to claim 1, wherein the average total reflectance of said color conversion sheet in the wavelength region of 440 nm to 470 nm is 30% to 60%.

5. The color conversion sheet according to claim 1, wherein the average total reflectance of said color conversion sheet in the wavelength region of 440 nm to 470 nm is 30% to 45%.

6. The color conversion sheet according to claim 1, wherein the color conversion sheet contains scattering particles.

7. The content of the scattering particles is 0.03 g / m ２ ~2.1g / m ２ The color conversion sheet according to claim 6 .

8. The color conversion sheet according to claim 6, wherein the scattering particles include titania particles.

9. The color conversion sheet according to claim 1, wherein the color conversion sheet comprises at least a color conversion layer (A) and a color conversion layer (B), the color conversion layer (A) contains a luminescent material (a) that emits light having a peak wavelength observed in the region of 500 nm or more and less than 580 nm, and the color conversion layer (B) contains a luminescent material (b) that emits light having a peak wavelength observed in the region of 580 nm or more and 750 nm or less.

10. The color conversion sheet according to claim 9, wherein the luminescent material (a) and / or the luminescent material (b) is an organic luminescent material.

11. The color conversion sheet according to claim 9, wherein the organic light-emitting material (a) and / or the light-emitting material (b) contains a compound represented by general formula (1): X is C-R ７ or N; R １ ~R ９ may be the same or different and are selected from hydrogen, an alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an alkynyl group, a hydroxyl group, a thiol group, an alkoxy group, an alkylthio group, an aryl ether group, an aryl thioether group, an aryl group, a heteroaryl group, a halogen, a cyano group, an aldehyde group, a carbonyl group, a carboxyl group, an oxycarbonyl group, a carbamoyl group, an amino group, a nitro group, a silyl group, a siloxanyl group, a boryl group, a phosphine oxide group, and a fused ring and an aliphatic ring formed between adjacent substituents.

12. The color conversion sheet according to claim 9, wherein at least one of the color conversion layer (A) and the color conversion layer (B) contains scattering particles.

13. A light source unit comprising a light source and the color conversion sheet according to claim 1.

14. The light source unit according to claim 13, wherein the light extraction layer of the color conversion sheet is disposed on the side opposite to the light source.

15. A light source unit including a light source and the color conversion sheet according to claim 3, wherein the color conversion sheet is arranged so that the second surface of the color conversion sheet faces the light source side.

16. The light source unit according to claim 13, wherein the light source is a light emitting diode having a maximum emission in the range of 400 nm to 500 nm.

17. A display comprising a light source unit according to any one of claims 13 to 16.

18. A lighting device comprising a light source unit according to any one of claims 13 to 16.

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