Wavelength conversion member and manufacturing method therefor

Abstract

The present invention provides a wavelength conversion member that suppresses discoloration from the end portion thereof. The wavelength conversion member includes a laminate comprising a wavelength conversion layer containing quantum dots and two barrier layers laminated on one principal surface and the other principal surface of the wavelength conversion layer, respectively. In the wavelength conversion member, the barrier layers have a first modification part at least on a portion of the end surfaces thereof, the wavelength conversion layer has a second modification part at least on a portion of the end surface thereof, and at least a portion of the second modification part is exposed together with the barrier layers on the end surface of the laminate.

Description

Wavelength conversion member and method for manufacturing the same

[0001] The present disclosure relates to a wavelength conversion member and a method for manufacturing the same.

[0002] In the field of image display devices such as liquid crystal display devices, the use of quantum dots that convert the wavelength of incident light and emit the converted light has been proposed in order to improve color reproducibility. For example, International Publication No. 2016 / 039079 proposes a functional laminate film having a functional layer laminate including a quantum dot-containing functional layer and two gas barrier films, and an end surface protection layer that covers the end surfaces of the functional layer laminate.

[0003] In a sheet-shaped wavelength conversion member containing quantum dots, discoloration may progress from the edges over time. One aspect of the present disclosure aims to provide a wavelength conversion member in which discoloration from the edges is suppressed, and a method for manufacturing the same.

[0004] The first aspect is a wavelength conversion member including a laminate including a wavelength conversion layer containing quantum dots and two barrier layers respectively stacked on one main surface and the other main surface of the wavelength conversion layer. The barrier layer has a first modified portion on at least a part of its end surface, and the wavelength conversion layer has a second modified portion on at least a part of its end surface. In the wavelength conversion member, at least a part of the second modified portion is exposed at the end surface of the laminate.

[0005] In a second aspect, a method for producing a wavelength conversion member includes: preparing a laminate sheet including a wavelength conversion layer containing quantum dots and two barrier layers laminated on one main surface and the other main surface of the wavelength conversion layer, and cutting the laminate sheet into individual laminates by irradiating the laminate sheet with laser light that intersects the main surface of the laminate sheet. The laser light irradiation has a frequency of 5 kHz to 30 kHz, a scanning speed of 50 mm / s to 100 mm / s, and a laser light output of 3.4 W to 100 W.

[0006] According to one aspect of the present disclosure, it is possible to provide a wavelength conversion member in which fading from the edge is suppressed, and a method for manufacturing the same.

[0007] 1 is an example of an X-ray diffraction pattern of a nanoparticle precursor according to Reference Example 1. FIG. 2 is an example of a transmission electron microscope image of quantum dots according to Reference Example 1. FIG. 3 is a schematic cross-sectional view showing one aspect of an end portion of a laminate. FIG. 4 is an example of a backscattered electron image of a cut surface of a wavelength conversion member according to Comparative Example 1, taken by a cutting machine. FIG. 5 is an example of a backscattered electron image of a cut surface of a wavelength conversion member according to Example 3, taken by a laser beam. FIG. 6 is an example of a fluorescence microscope image of a cross section of an end portion of a wavelength conversion member according to Comparative Example 1, taken by a cutting machine. FIG. 7 is an example of a fluorescence microscope image of a cross section of an end portion of a wavelength conversion member according to Example 3, taken by a laser beam. FIG. 8 is a schematic cross-sectional view showing one aspect of a wavelength conversion member.

[0008] As used herein, the term "process" refers not only to an independent process, but also to processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. Furthermore, the content of each component in a composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. In this specification, the relationship between color names and chromaticity coordinates, the relationship between light wavelength ranges and monochromatic light color names, etc., conforms to JIS Z8110. The half-width of a phosphor refers to the wavelength width (full width at half maximum; FWHM) of the emission spectrum of a light-emitting material, where the emission intensity is 50% of the maximum emission intensity. As used herein, terms such as "sheet," "film," and "layer" are not distinguished from each other solely based on differences in name. Thus, for example, "film" and "layer" are used to include components that may also be called sheets, and "sheet" and "layer" are used to include components that may also be called films. In this specification, the term "layer" includes not only a case where the layer is formed over the entire region when the region where the layer is present is observed, but also a case where the layer is formed only in a portion of the region. The term "laminated" refers to stacking layers, and two or more layers may be bonded or detachable. In this specification, terms such as wavelength conversion layer and barrier layer may be used both before and after cutting. The size, positional relationship, etc. of components shown in each drawing may be exaggerated for clarity. In the following description, the same names and symbols indicate identical or similar components, and detailed description will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured with the same material, so that multiple elements are served by one material, or conversely, the function of one material may be shared by multiple materials. In this specification, when a layer, film, or other part is described as being "on" or "above" another part, this includes not only the case where the layer is "directly above" the other part, but also the case where there is another part in between.Furthermore, "arranged on" includes not only the upper side but also the lower side. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments described below are merely examples of wavelength conversion members and manufacturing methods thereof for embodying the technical concept of the present invention, and the present invention is not limited to the wavelength conversion members and manufacturing methods thereof described below.

[0009] Wavelength conversion member The wavelength conversion member includes a laminate including a wavelength conversion layer containing quantum dots and two barrier layers respectively stacked on one main surface and the other main surface of the wavelength conversion layer. The barrier layer has a first modified portion on at least a part of its end surface, and the wavelength conversion layer has a second modified portion on at least a part of its end surface. In the laminate constituting the wavelength conversion member, at least a part of the second modified portion is exposed at the end surface of the laminate. The wavelength conversion member may include the laminate and an end surface covering layer arranged to cover the end surface of the laminate.

[0010] The wavelength conversion layer includes two barrier layers, and the first and second modified regions are formed on the end surfaces of the laminate by, for example, irradiation with laser light, thereby suppressing fading of the wavelength conversion member from the end surface over time. This can be attributed to, for example, the formation of the first and second modified regions that can sufficiently suppress the penetration of moisture and the like by irradiating the laminate with laser light under conditions in which at least a portion of the second modified region is exposed at the end surface of the laminate. Furthermore, the first modified region covers the interface between the barrier layer and the wavelength conversion layer, thereby suppressing the influence of the external environment from the interface.

[0011] The laminate has two opposing main surfaces and end surfaces surrounding the outer edges of the main surfaces in the stacking direction. The opposing main surfaces correspond to the main surfaces of the barrier layers. The end surfaces of the laminate are arranged along the outer edges of the main surfaces and are composed of surfaces that intersect with the main surfaces. The end surfaces of the laminate may be, for example, approximately perpendicular to the main surfaces of the laminate. Furthermore, the outer edges of the main surfaces of the laminate may be surrounded by four planar end surfaces, or may be surrounded by an end surface including at least one curved end surface.

[0012] The wavelength conversion layer contains quantum dots. Quantum dots are semiconductor crystal particles with particle diameters of several nanometers to several tens of nanometers. When the size of a material is reduced to the nanometer order, electrons can only exist in a limited state within the material. Therefore, the electronic state becomes discrete, and the band gap changes depending on the particle size. Quantum dots absorb light and emit light with a wavelength corresponding to the band gap energy. Therefore, by controlling the particle size, crystal composition, etc., the emission wavelength of the quantum dots can be controlled, and the quantum dots function as a wavelength conversion material. The particle diameter of the quantum dots contained in the wavelength conversion layer may be, for example, 50 nm or less. The particle diameter of the quantum dots may preferably be 1 nm or more and 20 nm or less, 1.6 nm or more and 8 nm or less, or 2 nm or more and 7.5 nm or less.

[0013] Here, the particle size of the semiconductor nanoparticles constituting the quantum dots refers to the longest line segment connecting any two points on the periphery of the particle observed in a transmission electron microscope (TEM) image and passing through the center of the particle. The average particle size of the semiconductor nanoparticles refers to the arithmetic mean value of the particle sizes measured for semiconductor nanoparticles observed in a TEM image whose particle sizes can be measured.

[0014] When the semiconductor nanoparticles have a rod-like shape, the length of the minor axis is considered to be the particle size. Here, rod-like particles refer to particles that, when observed on a surface including the major axis, are observed as quadrilaterals (the cross section is circular, elliptical, or polygonal), including rectangular shapes long in one direction, ellipsoids, or polygonal shapes (e.g., pencil-like shapes), and the ratio of the length of the major axis to the length of the minor axis is greater than 1.2. For rod-like particles, the length of the major axis refers to the longest line segment connecting any two points on the periphery of the particle in the case of an elliptical shape, and in the case of a quadrilateral or polygonal shape, refers to the longest line segment that is parallel to the longest side defining the periphery and connects any two points on the periphery of the particle. The length of the minor axis refers to the longest line segment that is perpendicular to the line segment defining the length of the major axis and connects any two points on the periphery. Specifically, the average particle size of semiconductor nanoparticles is determined by measuring the particle size of all measurable semiconductor nanoparticles observed in a TEM image at a magnification of 50,000 times or more and 150,000 times or less, and calculating the arithmetic mean of these particle sizes. Here, "measurable" particles are those whose entire outline can be observed in a TEM image. Therefore, particles that are "cut off" because some of them are not included in the imaging range in a TEM image are not measurable. When a single TEM image contains a total of 100 or more nanoparticles, the average particle size is determined using that single TEM image. When the number of nanoparticles contained in a single TEM image is small, the imaging location is changed, additional TEM images are obtained, and the particle sizes of 100 or more particles contained in two or more TEM images are measured to determine the average particle size.

[0015] Specific examples of quantum dots include perovskite quantum dots, chalcopyrite quantum dots, and indium phosphide (InP) quantum dots. The perovskite quantum dots may contain, for example, a compound represented by the following formula (1): [M １ ｗ A １ （１－ｗ） ] ｘ M ２ ｙ X ｚ (1)

[0016] In the formula (1), M １ represents a first element including at least one element selected from the group consisting of Cs, Rb, K, Na, and Li. １ represents a nonmetallic cation containing at least one selected from the group consisting of an ammonium ion, a formamidinium ion, a guanidinium ion, an imidazolium ion, a pyridinium ion, a pyrrolidinium ion, and a protonated thiourea ion. ２ represents a second element containing at least one selected from the group consisting of Ge, Sn, Pb, Sb, and Bi. X represents an anion or a ligand containing at least one selected from the group consisting of chloride ions, bromide ions, iodide ions, cyanide ions, thiocyanate, isothiocyanate, and sulfide. x is a number from 1 to 4, y is a number from 1 to 2, z is a number from 3 to 9, and w is a number from 0 to 1. In the formula (1), the first element M １ and nonmetallic cation A １ When both of the first element M １ and nonmetallic cation A １ Both represent atomic groups that constitute a ligand.

[0017] The ammonium ion may be represented, for example, by formula (A-1) below. The formamidinium ion may be represented, for example, by formula (A-2) below. The guanidinium ion may be represented, for example, by formula (A-3) below. The protonated thiourea ion may be represented, for example, by formula (A-4) below. The imidazolium ion may be represented, for example, by formula (A-5) below. The pyridinium ion may be represented, for example, by formula (A-6) below. The pyrrolidinium ion may be represented, for example, by formula (A-7) below. In each formula representing a non-metal cation, R each independently represents at least one selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, a halogen atom, and a pseudohalogen. Any two R in each formula may be bonded to each other to form a nitrogen-containing aliphatic ring having 3 to 6 carbon atoms.

[0018] [R ４ N ＋ ] (A-1) [(NR ２ )２ RC ＋ ] (A-2) [(NR ２ ) ３ C ＋ ] (A-3) [(NR ２ ) ２ C ＋ -SR] (A-4)

[0019]

[0020] Perovskite quantum dots containing a compound having a composition represented by formula (1) emit green or red light when irradiated with light from a light source. For green light, the perovskite quantum dots may emit light having a peak emission wavelength in the range of 475 nm to 560 nm when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 545 nm, preferably a light source having a peak emission wavelength in the range of, for example, 380 nm to 500 nm. The peak emission wavelength of the green light-emitting perovskite quantum dots may be preferably in the range of 510 nm to 560 nm, 520 nm to 560 nm, or 525 nm to 535 nm. For red light, the perovskite quantum dots may emit light having a peak emission wavelength in the range of, for example, 600 nm to 680 nm when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 320 nm to 545 nm, preferably a light source having a peak emission wavelength in the range of, for example, 320 nm to 450 nm. The emission peak wavelength of the perovskite quantum dots that emit red light may be preferably in the range of 610 nm to 670 nm, 620 nm to 660 nm, or 625 nm to 635 nm. The half-width of the emission spectrum of the perovskite quantum dots may be, for example, 35 nm or less, preferably 30 nm or less, or 25 nm or less. The perovskite quantum dots may exhibit band-edge emission in the emission spectrum.

[0021] The first aspect of the chalcopyrite quantum dots may include, for example, a first semiconductor containing silver (Ag), indium (In), gallium (Ga), and sulfur (S), and a second semiconductor containing Ga and S may be disposed on the surface of the first semiconductor. The second semiconductor may further contain Ag. The first semiconductor may be a semiconductor having a chalcopyrite structure containing Ag, In, Ga, and S. In the first aspect of the chalcopyrite quantum dots, an attachment containing a second semiconductor may be disposed on the surface of a particle containing the first semiconductor, or the attachment containing the second semiconductor may coat the particle containing the first semiconductor. Furthermore, the chalcopyrite quantum dots may have a core-shell structure in which, for example, a particle containing the first semiconductor serves as a core, and an attachment containing the second semiconductor serves as a shell, and the shell is disposed on the surface of the core. For details of the chalcopyrite quantum dots of the first aspect, reference may be made to the descriptions in, for example, JP 2018-044142 A and WO 2022 / 191032.

[0022] The first semiconductor contains at least Ag, and a part of Ag is substituted with copper (Cu), gold (Au), and an alkali metal (hereinafter, M ａ The first semiconductor may further contain at least one of the elements other than Ag (sometimes referred to as "substantially Ag"), or may be substantially composed of Ag. Here, "substantially" indicates that the ratio of the number of atoms of elements other than Ag substituting for Ag to the total number of atoms of Ag and elements other than Ag substituting for Ag is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less. Furthermore, the first semiconductor may substantially be composed of Ag and alkali metals as constituent elements. Here, "substantially" indicates that the ratio of the number of atoms of elements other than Ag and alkali metals substituting for Ag to the total number of atoms of Ag, alkali metals, and elements other than Ag and alkali metals substituting for Ag is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less. Incidentally, alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs).

[0023] The first semiconductor may have a composition represented by the following formula (2a): (Ag ｐ Mａ （１－ｐ） ) ｑ In ｒ Ga （１－ｒ） S （ｑ＋３）／２ (2a) where p, q, and r satisfy 0<p≦1, 0.20<q≦1.2, and 0<r<1. M ａ indicates an alkali metal.

[0024] In the first embodiment of the chalcopyrite quantum dot, a second semiconductor may be disposed on the surface. The second semiconductor may include a semiconductor having a larger band gap energy than the first semiconductor. The second semiconductor may be a semiconductor consisting essentially of Ga and S. Alternatively, the second semiconductor may be a semiconductor consisting essentially of Ag, Ga, and S. Here, "substantially" indicates that, when the total number of atoms of all elements contained in the semiconductor containing Ga and S, or the semiconductor containing Ag, Ga, and S, is taken as 100%, the proportion of the number of atoms of elements other than Ga and S, or other than Ag, Ga, and S, is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0025] The chalcopyrite quantum dots of the first embodiment may exhibit band edge emission having a peak emission wavelength in the wavelength range of 475 nm to 560 nm (e.g., green) when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 545 nm, and the peak emission wavelength may preferably be in the range of 510 nm to 550 nm, 515 nm to 545 nm, or 525 nm to 535 nm. Furthermore, the chalcopyrite quantum dots of the first embodiment may have a half-width in their emission spectrum of, for example, 45 nm or less, preferably 40 nm or less, 35 nm or less, or 30 nm or less. The half-width may be, for example, 15 nm or more.

[0026] A second aspect of the chalcopyrite quantum dots may include, for example, a third semiconductor containing copper (Cu), silver (Ag), indium (In), gallium (Ga), and sulfur (S), and a fourth semiconductor containing Ga and S may be disposed on the surface of the third semiconductor. The fourth semiconductor may further contain Ag. The third semiconductor may be a semiconductor having a chalcopyrite structure containing Cu, Ag, In, Ga, and S. In the second aspect of the chalcopyrite quantum dots, an attachment containing the fourth semiconductor may be disposed on the surface of a particle containing the third semiconductor, or the attachment containing the fourth semiconductor may coat the particle containing the third semiconductor. Furthermore, the chalcopyrite quantum dots may have a core-shell structure in which, for example, a particle containing the third semiconductor serves as a core, and an attachment containing the fourth semiconductor serves as a shell, and the shell is disposed on the surface of the core. For details of the chalcopyrite quantum dots of the second aspect, reference can be made to the descriptions in, for example, WO 2020 / 162622 and WO 2023 / 013361.

[0027] The third semiconductor contains at least Ag and Cu, and a part of these is substituted with gold (Au) and an alkali metal (M ａ The third semiconductor may substantially contain Ag, Cu, and an alkali metal as constituent elements. Here, "substantially" indicates that the ratio of the number of atoms of elements other than Ag, Cu, and alkali metals to the total number of atoms of Ag, Cu, and alkali metals, and elements other than Ag, Cu, and alkali metals, is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0028] The third semiconductor may have a composition represented by the following formula (2b): (Ag ｓ Cu （１－ｓ） ) ｔ In ｕ Ga （１－ｕ） S （ｔ＋３）／２ (2b) where s, t, and u satisfy 0<s<1, 0.20<t≦1.2, and 0<u<1.

[0029] In the second embodiment of the chalcopyrite quantum dot, a fourth semiconductor may be disposed on the surface. The fourth semiconductor may include a semiconductor having a band gap energy larger than that of the third semiconductor. The fourth semiconductor may be a semiconductor consisting essentially of Ga and S. Alternatively, the fourth semiconductor may be a semiconductor consisting essentially of Ag, Ga, and S. Here, "substantially" indicates that, when the total number of atoms of all elements contained in the semiconductor containing Ga and S, or the semiconductor containing Ag, Ga, and S, is taken as 100%, the proportion of the number of atoms of elements other than Ga and S, or other than Ag, Ga, and S, is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0030] The chalcopyrite quantum dots of the second embodiment may exhibit band edge emission having a peak emission wavelength in the wavelength range of 600 nm to 680 nm (e.g., red) when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 545 nm, and the peak emission wavelength may be preferably in the range of 610 nm to 670 nm, 620 nm to 660 nm, or 625 nm to 635 nm. Furthermore, the chalcopyrite quantum dots of the second embodiment may have a half-width in their emission spectrum of, for example, 70 nm or less, preferably 65 nm or less, 60 nm or less, or 30 nm or less. The half-width may be, for example, 15 nm or more.

[0031] A third aspect of the chalcopyrite quantum dots may include, for example, a fifth semiconductor containing silver (Ag), gallium (Ga), and selenium (Se), and a sixth semiconductor containing zinc (Zn) and sulfur (S) may be disposed on the surface of the fifth semiconductor. The fifth semiconductor may contain at least Ag, Ga, and Se, and may be partially substituted with indium (In) and sulfur (S). The sixth semiconductor may further contain at least one of Ga and Se. The fifth semiconductor may be a semiconductor having a chalcopyrite structure containing Ag, Ga, and Se. In the third aspect of the chalcopyrite quantum dots, an attachment containing a sixth semiconductor may be disposed on the surface of a particle containing the fifth semiconductor, or the attachment containing the sixth semiconductor may coat the particle containing the fifth semiconductor. Furthermore, the chalcopyrite quantum dots may have a core-shell structure in which, for example, a particle containing the fifth semiconductor serves as a core, and an attachment containing the sixth semiconductor serves as a shell, and the shell is disposed on the surface of the core. For details of the chalcopyrite quantum dots of the third aspect, reference can be made to the descriptions in, for example, WO 2021 / 039290.

[0032] The fifth semiconductor contains at least Ag, Ga, and Se, and may contain indium (In) and sulfur (S) substituted for some of these elements.

[0033] The fifth semiconductor may have a composition represented by the following formula (2c), for example: AgIn ｘ Ga １－ｘ S ｙ Se １－ｙ (2c) where x and y satisfy 0≦x<1 and 0≦y≦1.

[0034] In a third aspect of the chalcopyrite quantum dot, a sixth semiconductor may be disposed on the surface. The sixth semiconductor may include a semiconductor having a band gap energy larger than that of the fifth semiconductor. The sixth semiconductor may be a semiconductor consisting essentially of Zn and S. Here, "substantially" indicates that, when the total number of atoms of all elements contained in the semiconductor, including Zn and S, is taken as 100%, the proportion of the number of atoms of elements other than Zn and S is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0035] The chalcopyrite quantum dots of the third embodiment may exhibit band edge emission having a peak emission wavelength in the wavelength range of 600 nm to 680 nm (e.g., red) when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 545 nm, and the peak emission wavelength may preferably be in the range of 610 nm to 670 nm, or 625 nm to 635 nm. Furthermore, the chalcopyrite quantum dots of the third embodiment may have a half-width in their emission spectrum of, for example, 50 nm or less, preferably 40 nm or less, or 30 nm or less. The half-width may be, for example, 15 nm or more.

[0036] Indium phosphide (InP) quantum dots are a type of semiconductor nanoparticles containing III-V semiconductors, such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs, and TiSb.

[0037] The III-V quantum dots may have a semiconductor nanoparticle containing a III-V semiconductor and an attachment containing a seventh semiconductor different from the III-V semiconductor constituting the semiconductor nanoparticle disposed on the surface thereof, or the attachment containing the seventh semiconductor may coat the particle containing the III-V semiconductor. Furthermore, the III-V quantum dots may have a core-shell structure, for example, in which a particle containing a III-V semiconductor serves as a core and an attachment containing the seventh semiconductor serves as a shell, with the shell disposed on the surface of the core. The seventh semiconductor may be a semiconductor with a larger bandgap energy than the III-V semiconductor. Examples of combinations of a III-V semiconductor and a seventh semiconductor include InP / ZnS, GaP / ZnS, InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, InP / ZnSTe, InGaP / ZnSTe, and InGaP / ZnSSe.

[0038] III-V semiconductor (e.g., indium phosphide-based) quantum dots may emit green or red light when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 500 nm. Green-emitting III-V semiconductor quantum dots may exhibit band-edge emission having a peak emission wavelength in the range of 475 nm to 580 nm when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 545 nm, preferably a light source having a peak emission wavelength in the range of, for example, 380 nm to 500 nm. The peak emission wavelength may preferably be in the range of 510 nm to 570 nm, 520 nm to 560 nm, or 525 nm to 535 nm. Furthermore, red-emitting III-V semiconductor quantum dots may exhibit band-edge emission having a peak emission wavelength in the wavelength range of 600 nm to 680 nm when irradiated with light from a light source having a peak emission wavelength in the range of, for example, 380 nm to 545 nm. The emission peak wavelength may be preferably in the range of 610 nm to 670 nm, 620 nm to 660 nm, or 625 nm to 635 nm. Furthermore, the III-V semiconductor quantum dots may have an emission spectrum with a half-width of, for example, 70 nm or less, preferably 65 nm or less, 60 nm or less, or 30 nm or less. The half-width may be, for example, 15 nm or more.

[0039] The quantum dots may contain other quantum dots than perovskite-based quantum dots, chalcopyrite-based quantum dots, and indium phosphide-based quantum dots, as necessary. Examples of other quantum dots include particles containing at least one semiconductor selected from the group consisting of II-VI group semiconductors, IV-VI group semiconductors, and IV group semiconductors.

[0040] Specific examples of II-VI group semiconductors include CdSe, CdTe, CdS, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, and the like. Specific examples of IV-VI semiconductors include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe, etc. Specific examples of IV semiconductors include Si, Ge, SiC, SiGe, etc.

[0041] The quantum dots may have a surface modifier disposed on their surfaces. Specific examples of the surface modifier include amino alcohols having 2 to 20 carbon atoms; ionic surface modifiers; nonionic surface modifiers; nitrogen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms; sulfur-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms; oxygen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms; phosphorus-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms; and halides containing at least one selected from the group consisting of Group 2 elements, Group 12 elements, and Group 13 elements. The surface modifiers may be used alone or in combination of two or more different types.

[0042] The amino alcohol used as a surface modifier may be any compound having an amino group and an alcoholic hydroxyl group, and including a hydrocarbon group having 2 to 20 carbon atoms. The number of carbon atoms in the amino alcohol is preferably 10 or less, more preferably 6 or less. The hydrocarbon group constituting the amino alcohol may be derived from a hydrocarbon such as a linear, branched, or cyclic alkane, alkene, or alkyne. "Derived from a hydrocarbon" means that the hydrocarbon group is formed by removing at least two hydrogen atoms from a hydrocarbon. Specific examples of amino alcohols include aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, and aminooctanol. For example, when the amino group of the amino alcohol is bonded to the surface of a semiconductor nanoparticle and the hydroxyl group is exposed on the opposite outermost surface of the particle, the polarity of the semiconductor nanoparticle changes, improving dispersibility in alcoholic solvents (e.g., methanol, ethanol, propanol, butanol, etc.).

[0043] Examples of ionic surface modifiers used as surface modifiers include nitrogen-containing compounds, sulfur-containing compounds, and oxygen-containing compounds having an ionic functional group in the molecule. The ionic functional group may be either cationic or anionic, and preferably has at least a cationic group. Specific examples of surface modifiers and surface modification methods can be found in, for example, Chemistry Letters, Vol. 45, pp. 898-900, 2016.

[0044] The ionic surface modifier may be, for example, a sulfur-containing compound having a tertiary or quaternary alkylamino group. The number of carbon atoms in the alkyl group of the alkylamino group may be, for example, 1 to 4. The sulfur-containing compound may also be an alkyl or alkenyl thiol having 2 to 20 carbon atoms. Specific examples of the ionic surface modifier include hydrogen halide salts of dimethylaminoethanethiol, halogen salts of trimethylammoniumethanethiol, hydrogen halide salts of dimethylaminobutanethiol, and halogen salts of trimethylammoniumbutanethiol.

[0045] Examples of nonionic surface modifiers used as surface modifiers include nitrogen-containing compounds, sulfur-containing compounds, and oxygen-containing compounds having nonionic functional groups including alkylene glycol units and alkylene glycol monoalkyl ether units. The number of carbon atoms in the alkylene group in the alkylene glycol unit may be, for example, 2 to 8, preferably 2 to 4. The number of repeating alkylene glycol units may be, for example, 1 to 20, preferably 2 to 10. The nitrogen-containing compound constituting the nonionic surface modifier may have an amino group, the sulfur-containing compound may have a thiol group, and the oxygen-containing compound may have a hydroxyl group. Specific examples of nonionic surface modifiers include methoxytriethyleneoxyethanethiol and methoxyhexaethyleneoxyethanethiol.

[0046] Examples of nitrogen-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include amines and amides. Examples of sulfur-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include thiols. Examples of oxygen-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include carboxylic acids, alcohols, ethers, aldehydes, and ketones. Examples of phosphorus-containing compounds having a hydrocarbon group with 4 to 20 carbon atoms include trialkylphosphines, triarylphosphines, trialkylphosphine oxides, and triarylphosphine oxides.

[0047] Examples of the halide containing at least one element selected from the group consisting of Group 2 elements, Group 12 elements, and Group 13 elements include magnesium chloride, calcium chloride, zinc chloride, cadmium chloride, aluminum chloride, and gallium chloride.

[0048] The quantum dots contained in the wavelength conversion layer may include at least one type selected from the group consisting of first quantum dots having an emission peak wavelength in the wavelength range of 475 nm to 560 nm and second quantum dots having an emission peak wavelength in the wavelength range of 600 nm to 680 nm. The quantum dots may include at least one type of first quantum dot and at least one type of second quantum dot. The first quantum dots may include at least one type selected from the group consisting of perovskite quantum dots, indium phosphide quantum dots, and the first embodiment of chalcopyrite quantum dots. Preferably, the first quantum dots may include at least one type selected from the group consisting of perovskite quantum dots and the first embodiment of chalcopyrite quantum dots. Furthermore, the second quantum dots may include at least one type selected from the group consisting of perovskite quantum dots, the second embodiment of chalcopyrite quantum dots, and indium phosphide quantum dots. Preferably, the second quantum dots may comprise at least one selected from the group consisting of the chalcopyrite quantum dots and indium phosphide quantum dots of the second aspect. When the wavelength conversion layer comprises the first quantum dots and the second quantum dots, green light and red light are emitted from the first quantum dots and the second quantum dots, respectively, when the wavelength conversion layer is irradiated with blue light having a wavelength of, for example, 420 nm or more and 460 nm or less. As a result, white light is obtained by mixing the green light and red light emitted from the first quantum dots and the second quantum dots with the blue light transmitted through the wavelength conversion layer.

[0049] The wavelength conversion layer constituting the laminate may be one layer or two or more layers. For example, when the wavelength conversion layer is two layers, one wavelength conversion layer may contain first quantum dots and the other wavelength conversion layer may contain second quantum dots. The wavelength conversion layer may contain, for example, chalcopyrite quantum dots that emit green light and chalcopyrite quantum dots that emit red light. The wavelength conversion layer may contain chalcopyrite quantum dots that emit green light and indium phosphide quantum dots that emit red light. The wavelength conversion layer may contain perovskite quantum dots that emit green light and indium phosphide quantum dots that emit red light. The wavelength conversion layer may contain perovskite quantum dots that emit green light and chalcopyrite quantum dots that emit red light. Furthermore, the wavelength conversion layer may include, for example, a layer containing chalcopyrite quantum dots that emit green light and a layer containing chalcopyrite quantum dots that emit red light. The wavelength conversion layer may include a layer containing chalcopyrite quantum dots that emit green light and a layer containing indium phosphide quantum dots that emit red light. The wavelength conversion layer may include a layer containing perovskite quantum dots that emit green light and a layer containing indium phosphide quantum dots that emit red light. The wavelength conversion layer may include a layer containing perovskite quantum dots that emit green light and a layer containing chalcopyrite quantum dots that emit red light.

[0050] The wavelength conversion layer may contain, in addition to quantum dots, at least one phosphor as a light-emitting material other than quantum dots, as necessary. Examples of the phosphor that can be used include garnet-based phosphors such as aluminum garnet. Examples of garnet-based phosphors include cerium-activated yttrium-aluminum garnet-based phosphors and cerium-activated lutetium-aluminum garnet-based phosphors. In addition to garnet-based phosphors, nitrogen-containing calcium aluminosilicate phosphors activated with europium and / or chromium, europium-activated silicate phosphors, β-SiAlON-based phosphors, nitride-based phosphors such as CASN-based or SCASN-based phosphors, and LnSi ３ N １１rare earth nitride phosphors such as BaSi ２ O ２ N ２ : Eu-based or Ba-based ３ Si ６ O １２ N ２ : Eu-based oxynitride phosphors, CaS-based phosphors, SrGa ２ S ４ Sulfide-based phosphors such as ZnS-based phosphors, chlorosilicate-based phosphors, SrLiAl ３ N ４ : Eu phosphor, SrMg ３ SiN ４ : Eu phosphor, K as a manganese-activated fluoride complex phosphor ２ SiF ６ : Mn phosphor and K ２ (Si,Al)F ６ : Mn phosphor (e.g., K ２ Si ０．９９ Al ０．０１ F ５．９９ :Mn) can be used. In this specification, in a formula representing the composition of a phosphor, multiple elements separated by a comma (,) mean that at least one of these multiple elements is contained in the composition. Furthermore, in a formula representing the composition of a phosphor, the part before the colon (:) represents the host crystal, and the part after the colon (:) represents the activator element.

[0051] The wavelength conversion layer may include, for example, green-emitting chalcopyrite quantum dots and red-emitting manganese-activated fluoride complex phosphors, or may include green-emitting perovskite quantum dots and red-emitting manganese-activated fluoride complex phosphors. The wavelength conversion layer may also include a layer containing green-emitting chalcopyrite quantum dots and a layer containing red-emitting manganese-activated fluoride complex phosphors. Furthermore, the wavelength conversion layer may include a layer containing green-emitting perovskite quantum dots and a layer containing red-emitting manganese-activated fluoride complex phosphors.

[0052] The wavelength conversion layer may contain a cured resin in addition to the quantum dots. The cured resin may be a cured product of the photocurable composition described below. The content of the quantum dots contained in the wavelength conversion layer may be, for example, 0.01% by mass or more and 1.0% by mass or less, preferably 0.05% by mass or more and 0.5% by mass or less, or 0.1% by mass or more and 0.5% by mass or less, relative to the total amount of the cured resin. When the content of the quantum dots is 0.01% by mass or more, sufficient luminescence intensity tends to be obtained when irradiated with light, and when the content of the quantum dots is 1.0% by mass or less, aggregation of the quantum dots tends to be suppressed, and color unevenness tends to be suppressed.

[0053] The photocurable composition that forms the cured resin may contain, for example, a (meth)acrylic compound. The (meth)acrylic compound may be a monofunctional (meth)acrylic compound having one (meth)acryloyl group per molecule, or a polyfunctional (meth)acrylic compound having two or more (meth)acryloyl groups per molecule. As the (meth)acrylic compound, one type may be used alone, or two or more types may be used in combination, and a monofunctional (meth)acrylic compound and a polyfunctional (meth)acrylic compound may be used in combination. Here, the (meth)acrylic compound includes an acrylic compound, a methacrylic compound, and a mixture thereof, and the same applies to similar notations.

[0054] Specific examples of the monofunctional (meth)acrylic compound include (meth)acrylic acid; alkyl (meth)acrylates in which the alkyl group has 1 to 18 carbon atoms, such as methyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isononyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylate compounds having an aromatic ring, such as benzyl (meth)acrylate and phenoxyethyl (meth)acrylate; aminoalkyl (meth)acrylates, such as N,N-dimethylaminoethyl (meth)acrylate; (meth)acrylate compounds having an alicyclic group, such as cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and methylene oxide-added cyclodecatriene (meth)acrylate; (meth)acrylate compounds having a heterocyclic group such as (meth)acryloylmorpholine; fluorinated alkyl (meth)acrylates such as heptadecafluorodecyl (meth)acrylate; (meth)acrylate compounds having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate; (meth)acrylate compounds having an isocyanate group such as 2-(2-(meth)acryloyloxyethyloxy)ethyl isocyanate, 2-(meth)acryloyloxyethyl isocyanate; (meth)acrylamide compounds such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, 2-hydroxyethyl(meth)acrylamide; and the like.

[0055] From the viewpoint of the heat resistance and moist heat resistance of the cured product, the polyfunctional (meth)acrylic compound is preferably a compound having two to four (meth)acryloyl groups in the molecule, and more preferably a compound having three (meth)acryloyl groups in the molecule.

[0056] Specific examples of polyfunctional (meth)acrylic compounds include alkylene glycol di(meth)acrylates such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate; tri(meth)acrylate compounds such as trimethylolpropane tri(meth)acrylate and tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate; and tetra(meth)acrylate compounds such as trimethylolpropane tetra(meth)acrylate and pentaerythritol tetra(meth)acrylate.

[0057] The (meth)acrylic compound may contain a monofunctional (meth)acrylate compound having an alicyclic group, or may contain isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, or the like, preferably isobornyl (meth)acrylate, from the viewpoint of further improving the heat resistance and moist heat resistance of the cured product.

[0058] The content of the (meth)acrylic compound in the photocurable composition may be, for example, 10% by mass or more and 50% by mass or less, and preferably 15% by mass or more and 45% by mass or less, or 20% by mass or more and 40% by mass or less, relative to the total amount of the photocurable composition. When the content of the (meth)acrylic compound is 10% by mass or more, the storage stability of the photocurable composition and the adhesion of the cured product tend to be further improved, and when the content of the (meth)acrylic compound is 50% by mass or less, the heat resistance and moist heat resistance of the cured product tend to be further improved.

[0059] The photocurable composition may contain, for example, a (meth)allyl compound. The (meth)allyl compound may be a monofunctional (meth)allyl compound having one (meth)allyl group per molecule, or a polyfunctional (meth)allyl compound having two or more (meth)allyl groups per molecule. As the (meth)allyl compound, one type may be used alone, or two or more types may be used in combination, and a monofunctional (meth)allyl compound and a polyfunctional (meth)allyl compound may be used in combination. From the viewpoint of further improving the adhesion of the cured product, it is preferable that the (meth)allyl compound contains a polyfunctional (meth)allyl compound. The ratio of the polyfunctional (meth)allyl compound to the total amount of (meth)allyl compounds may be, for example, 80% by mass or more, preferably 90% by mass or more, or may be 100% by mass.

[0060] Specific examples of the monofunctional (meth)allyl compound include (meth)allyl acetate, (meth)allyl propionate, (meth)allyl benzoate, (meth)allyl phenyl acetate, (meth)allyl phenoxy acetate, (meth)allyl methyl ether, and (meth)allyl glycidyl ether.

[0061] From the viewpoint of the heat resistance and moist heat resistance of the cured product, the polyfunctional (meth)allyl compound is preferably a compound having 2 to 4 (meth)allyl groups in the molecule, and more preferably a compound having 3 (meth)allyl groups in the molecule.

[0062] Specific examples of polyfunctional (meth)allyl compounds include di(meth)allyl cyclohexanedicarboxylate, di(meth)allyl maleate, di(meth)allyl adipate, di(meth)allyl phthalate, di(meth)allyl isophthalate, di(meth)allyl terephthalate, glycerin di(meth)allyl ether, trimethylolpropane di(meth)allyl ether, pentaerythritol di(meth)allyl ether, 1,3-di(meth)allyl-5-glycidyl isocyanurate, tri(meth)allyl cyanurate, tri(meth)allyl isocyanurate, tri(meth)allyl trimellitate, tetra(meth)allyl pyromellitate, 1,3,4,6-tetra(meth)allyl glycoluril, 1,3,4,6-tetra(meth)allyl-3a-methylglycoluril, and 1,3,4,6-tetra(meth)allyl-3a,6a-dimethylglycoluril. Among these, from the viewpoint of the heat resistance and moist heat resistance of the cured product, it is preferable to use at least one selected from the group consisting of tri(meth)allyl cyanurate, tri(meth)allyl isocyanurate, di(meth)allyl phthalate, di(meth)allyl isophthalate, di(meth)allyl terephthalate, and di(meth)allyl cyclohexanedicarboxylate, and tri(meth)allyl isocyanurate is more preferable.

[0063] The content of the (meth)allyl compound in the curable composition may be, for example, 1% by mass or more and 30% by mass or less, and preferably 5% by mass or more and 20% by mass or less, or 10% by mass or more and 15% by mass or less, relative to the total amount of the curable composition. When the content of the (meth)allyl compound is 1% by mass or more, the heat resistance and moist heat resistance of the cured product tend to be further improved, and when the content of the (meth)allyl compound is 30% by mass or less, the adhesion of the cured product tends to be further improved.

[0064] The photocurable composition preferably contains an alkyleneoxy group-containing compound having an alkyleneoxy group and a polymerizable reactive group. This tends to facilitate the preparation of a curable composition with high viscosity, and tends to suppress the coalescence of dispersoids due to aggregation when the mixture of the components is stirred to prepare the curable composition, which is an emulsion of the resin component and dispersoids. As a result, high dispersion quality is maintained, and the wavelength conversion member tends to have excellent luminescence intensity.

[0065] The alkyleneoxy group-containing compound preferably has an ester group. This tends to improve the dispersibility of dispersoids such as modified silicone. The alkyleneoxy group-containing compound may have one or more ester groups, and preferably has two or more ester groups.

[0066] The alkyleneoxy group-containing compound preferably has two or more polymerizable reactive groups, more preferably has two polymerizable reactive groups. By having two or more polymerizable reactive groups, the adhesiveness, heat resistance, and moist heat resistance of the cured product tend to be further improved. Examples of the polymerizable reactive group include a functional group having an ethylenic double bond, more specifically, a (meth)acryloyl group.

[0067] As the alkyleneoxy group, from the viewpoint that a high-viscosity curable composition can be more easily prepared by increasing the viscosity of the alkyleneoxy group-containing compound, an alkyleneoxy group having 2 or more carbon atoms is preferred, an alkyleneoxy group having 2 or 3 carbon atoms is more preferred, and an alkyleneoxy group having 2 carbon atoms is even more preferred. The alkyleneoxy group-containing compound may have one type of alkyleneoxy group or two or more types of alkyleneoxy groups.

[0068] The alkyleneoxy group-containing compound may be a polyalkyleneoxy group-containing compound having a polyalkyleneoxy group containing a plurality of alkyleneoxy groups.

[0069] The alkyleneoxy group-containing compound may have 2 to 30 alkyleneoxy groups, preferably 2 to 20, 3 to 10, or 3 to 5 alkyleneoxy groups.

[0070] The alkyleneoxy group-containing compound preferably has a bisphenol structure, which tends to provide excellent moist heat resistance. Examples of the bisphenol structure include a bisphenol A structure and a bisphenol F structure, and among these, the bisphenol A structure is preferred.

[0071] Specific examples of the alkyleneoxy group-containing compound include alkoxyalkyl (meth)acrylates such as butoxyethyl (meth)acrylate; polyalkylene glycol monoalkyl ether (meth)acrylates such as diethylene glycol monoethyl ether (meth)acrylate, triethylene glycol monobutyl ether (meth)acrylate, tetraethylene glycol monomethyl ether (meth)acrylate, hexaethylene glycol monomethyl ether (meth)acrylate, octaethylene glycol monomethyl ether (meth)acrylate, nonaethylene glycol monomethyl ether (meth)acrylate, dipropylene glycol monomethyl ether (meth)acrylate, heptapropylene glycol monomethyl ether (meth)acrylate, and tetraethylene glycol monoethyl ether (meth)acrylate; polyalkylene glycol monoaryl ether (meth)acrylates such as hexaethylene glycol monophenyl ether (meth)acrylate; and heterocyclic alkylene glycols such as tetrahydrofurfuryl (meth)acrylate. (meth)acrylate compounds having a hydroxyl group such as triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, hexaethylene glycol mono(meth)acrylate, and octapropylene glycol mono(meth)acrylate; (meth)acrylate compounds having a glycidyl group such as glycidyl (meth)acrylate; polyalkylene glycol compounds such as polyethylene glycol di(meth)acrylate and polypropylene glycol di(meth)acrylate; tri(meth)acrylate compounds such as ethylene oxide-added trimethylolpropane tri(meth)acrylate; tetra(meth)acrylate compounds such as ethylene oxide-added pentaerythritol tetra(meth)acrylate; bisphenol-type di(meth)acrylate compounds such as ethoxylated bisphenol A-type di(meth)acrylate, propoxylated bisphenol A-type di(meth)acrylate, and propoxylated ethoxylated bisphenol A-type di(meth)acrylate; and the like.Among the alkyleneoxy group-containing compounds, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, and propoxylated ethoxylated bisphenol A di(meth)acrylate are preferred, with ethoxylated bisphenol A di(meth)acrylate being more preferred. One type of alkyleneoxy group-containing compound may be used alone, or two or more types may be used in combination.

[0072] When the photocurable composition contains an alkyleneoxy group-containing compound, the content of the alkyleneoxy group-containing compound in the photocurable composition may be, for example, 0.5% by mass or more and 10% by mass or less, and preferably 1% by mass or more and 8% by mass or less, or 1.5% by mass or more and 5% by mass or less, relative to the total amount of the photocurable composition. When the content of the alkyleneoxy group-containing compound is 0.5% by mass or more, the photocurable composition tends to be easily highly viscous, while when the content of the alkyleneoxy group-containing compound is 10% by mass or less, the viscosity of the photocurable composition does not become too high, and the production efficiency of the wavelength conversion member tends to be excellent.

[0073] The photocurable composition may contain at least one photopolymerization initiator, such as a compound that generates radicals when irradiated with active energy rays such as ultraviolet rays.

[0074] Specific examples of the photopolymerization initiator include benzophenone, N,N'-tetraalkyl-4,4'-diaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4,4'-bis(dimethylamino)benzophenone (also known as "Michler's ketone"), 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 1-hydroxycyclohexane, 1-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one ... Aromatic ketone compounds such as 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-(2-hydroxyethoxy)-phenyl)-2-hydroxy-2-methyl-1-propan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; quinone compounds such as alkylanthraquinone and phenanthrenequinone; benzoin compounds such as benzoin and alkylbenzoin; benzoin ethers such as benzoin alkyl ethers and benzoin phenyl ether compounds; benzyl derivatives such as benzyl dimethyl ketal; 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer, 2-(o-chlorophenyl)-4,5-di(m-methoxyphenyl)imidazole dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazole dimer, 2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer, 2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer, etc. acridine derivatives such as 9-phenylacridine and 1,7-(9,9'-acridinyl)heptane; oxime ester compounds such as 1,2-octanedione 1-[4-(phenylthio)-2-(O-benzoyloxime)] and ethanone 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime); coumarin compounds such as 7-diethylamino-4-methylcoumarin; thioxanthone compounds such as 2,4-diethylthioxanthone;Acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide; etc. The photopolymerization initiator may be used alone or in combination of two or more types.

[0075] As the photopolymerization initiator, from the viewpoint of curability, at least one selected from the group consisting of an acylphosphine oxide compound, an aromatic ketone compound, and an oxime ester compound is preferable, at least one selected from the group consisting of an acylphosphine oxide compound and an aromatic ketone compound is more preferable, and an acylphosphine oxide compound is even more preferable.

[0076] The content of the photopolymerization initiator in the photocurable composition may be, for example, 0.1% by mass or more and 5% by mass or less, and preferably 0.1% by mass or more and 3% by mass or less, or 0.5% by mass or more and 1.5% by mass or less, relative to the total amount of the photocurable composition. When the content of the photopolymerization initiator is 0.1% by mass or more, the sensitivity of the photocurable composition tends to be sufficient, and when the content of the photopolymerization initiator is 5% by mass or less, the effect on the hue of the photocurable composition and the decrease in storage stability tend to be suppressed.

[0077] The curable composition may contain a liquid medium. The liquid medium refers to a medium that is in a liquid state at room temperature (25°C). Examples of liquid media include ketone solvents, ether solvents, carbonate solvents, ester solvents, aprotic polar solvents, alcohol solvents, glycol monoether solvents, aromatic hydrocarbon solvents, terpene solvents, saturated aliphatic monocarboxylic acids, and unsaturated aliphatic monocarboxylic acids. The curable composition may contain one type of liquid medium alone, or may contain two or more types of liquid media.

[0078] When the photocurable composition contains a liquid medium, the content of the liquid medium in the photocurable composition may be, for example, 1 mass % or more and 10 mass % or less, and preferably 4 mass % or more and 10 mass % or less, or 4 mass % or more and 7 mass % or less, relative to the total amount of the photocurable composition.

[0079] The photocurable composition may contain other components, as necessary, such as a polymerization inhibitor, a silane coupling agent, a surfactant, an adhesion promoter, an antioxidant, etc. The photocurable composition may contain one type of each of the other components alone, or two or more types.

[0080] The photocurable composition may further contain quantum dots. The photocurable composition containing quantum dots can be prepared, for example, by mixing quantum dots, a (meth)acrylic compound, an alkyleneoxy group-containing compound, a photopolymerization initiator, and, if necessary, the above-mentioned components, using a conventional method. The quantum dots are preferably mixed in the form of a quantum dot dispersion dispersed in, for example, a monofunctional (meth)acrylate compound having an alicyclic group and a liquid medium.

[0081] The wavelength conversion layer can be formed by curing a photocurable composition containing quantum dots. Specifically, for example, a photocurable composition containing quantum dots is applied between two barrier layers, and the photocurable composition is cured by light irradiation to form a wavelength conversion layer containing quantum dots and a cured resin.

[0082] The wavelength and dose of light irradiated when forming the wavelength conversion layer can be appropriately set depending on the composition of the photocurable composition. ２ More than 5000mJ / cm ２ The irradiation dose is as follows: Examples of ultraviolet light sources include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and ultraviolet light-emitting diodes (UV-LEDs).

[0083] The wavelength conversion layer may be formed in the form of a film having two opposing main surfaces and end surfaces surrounding the outer edges of the main surfaces. When the wavelength conversion layer is in the form of a film, the average thickness of the wavelength conversion layer corresponding to the height of the end surfaces may be, for example, 30 μm or more and 200 μm or less, preferably 30 μm or more and 150 μm or less, or 80 μm or more and 120 μm or less. When the average thickness is 30 μm or more, the wavelength conversion efficiency tends to be further improved, and when the average thickness is 200 μm or less, when applied to a backlight unit, the backlight unit tends to be thinner. The average thickness of the film-like cured product is determined, for example, as the arithmetic mean value of thicknesses measured at any three points using a reflection spectroscopic film thickness meter or the like.

[0084] A barrier layer is laminated on each of the two main surfaces of the wavelength conversion layer to form a laminate. The barrier layer may be a barrier film having an inorganic layer, for example, in order to prevent a decrease in the luminous efficiency of the quantum dots.

[0085] The average thickness of the barrier layer may be, for example, from 20 μm to 150 μm, preferably from 20 μm to 120 μm, or from 25 μm to 100 μm. When the average thickness is 20 μm or more, functions such as barrier properties tend to be sufficient, and when the average thickness is 150 μm or less, a decrease in light transmittance tends to be suppressed. The average thickness of the barrier layer is determined in the same manner as for the film-like wavelength conversion layer.

[0086] The barrier layer preferably has a barrier property against oxygen. The oxygen permeability of the barrier layer is, for example, 0.5 mL / (m ２ 24h atm) or less, and preferably 0.3 mL / (m ２ ・24h・atm) or less, or 0.1mL / (m ２ The oxygen permeability of the barrier layer can be measured using an oxygen permeability measuring device (for example, OX-TRAN manufactured by MOCON) under conditions of a temperature of 23° C. and a relative humidity of 65%.

[0087] A barrier film having an inorganic layer constituting a barrier layer may have, for example, a substrate film and an inorganic layer provided on at least one main surface of the substrate film. Alternatively, for example, the barrier layer may be a laminate film including two substrate films and an inorganic layer disposed between the two substrate films. Examples of materials constituting the substrate film include thermoplastic resins such as polyester (e.g., polyethylene terephthalate, polyethylene naphthalate), cellulose triacetate, cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, polymethyl methacrylate, polycarbonate, and polyurethane. Preferred materials constituting the substrate film include polyester and cellulose triacetate.

[0088] The average thickness of the substrate film may be, for example, 10 μm or more and 150 μm or less, preferably 20 μm or more and 125 μm or less. When the average thickness of the substrate film is 10 μm or more, the occurrence of wrinkles and folds during assembly and handling of the wavelength conversion member is effectively suppressed. Furthermore, when the average thickness is 150 μm or less, it can contribute to reducing the weight and thickness of the image display device.

[0089] The substrate film may be composed of a single film or a laminated film composed of multiple films. Depending on the application, such a laminated film may be composed of multiple layers of films made of the same type of constituent material, or multiple layers of films made of different types of constituent material.

[0090] The inorganic layer may be a film made of an inorganic compound such as an oxide, a nitride, an oxynitride, or a carbide. Specific examples include metal oxides such as aluminum oxide, magnesium oxide, tantalum oxide, zirconium oxide, titanium oxide, and indium tin oxide (ITO); metal nitrides such as aluminum nitride; metal carbides such as aluminum carbide; silicon oxides such as silicon oxide, silicon oxynitride, silicon oxycarbide, and silicon oxynitride carbide; silicon nitrides such as silicon nitride and silicon carbide nitride; silicon carbides such as silicon carbide; and hydrides thereof. The inorganic layer may be made of one type of inorganic compound, or may be made of two or more types of inorganic compounds.

[0091] The average thickness of the inorganic layer may be, for example, 10 nm or more and 200 nm or less, preferably 10 nm or more and 100 nm or less, or 15 nm or more and 75 nm or less.

[0092] The inorganic layer may be formed by a known method depending on the material used, such as a plasma CVD method such as CCP-CVD or ICP-CVD, a sputtering method such as magnetron sputtering or reactive sputtering, a vacuum deposition method, or a vapor phase deposition method.

[0093] The barrier layer constituting the laminate may have a first modified region on at least a portion of its end face. The first modified region may have at least one oxygen-containing functional group (hereinafter also simply referred to as functional group) selected from the group consisting of a carboxy group, a hydroxy group, a carbonyl group, etc., on its surface. The presence of the functional group on the surface of the first modified region can be identified, for example, by measuring the infrared absorption spectrum of the surface of the first modified region. The infrared absorption spectrum can be measured by the attenuated total reflection (ATR) method using, for example, a Fourier transform infrared spectrometer (for example, manufactured by Thermo Fisher Scientific). Specifically, the carbonyl group will have a peak attributable to the CO stretching vibration (for example, at a wavenumber of 1725 cm). －１ The presence of a hydroxyl group can be identified by detecting a peak attributable to OH stretching vibration (for example, a peak at a wave number of 3300 cm －１The presence of the first modified region can be identified by detecting the first modified region. The first modified region can be formed, for example, by applying energy to the barrier layer.

[0094] The content of functional groups in the first modified region can be evaluated, for example, by measuring the infrared absorption spectrum of the surface of the first modified region. Specifically, for example, a peak attributed to CH stretching vibration (for example, a peak at a wave number of 2957 cm －１ ) intensity I １ ＣＨ The intensity I of the peak assigned to the CO stretching vibration is １ ＣＯ The ratio (I １ ＣＯ / I １ ＣＨ ), and the intensity of the peak assigned to the OH stretching vibration I １ ＯＨ The ratio (I １ ＯＨ / I １ ＣＨ ) on the surface of the first modified portion, the content of each functional group can be evaluated. １ ＣＯ / I １ ＣＨ ) may be, for example, 0.1 or more and 30 or less, preferably 0.5 or more, 1 or more, 5 or more, 7 or more, or 9 or more, and preferably 20 or less, 15 or less, 14 or less, 12 or less, or 11 or less. In addition, the ratio (I １ ＯＨ / I １ ＣＨ ) may be, for example, 0.1 or more and 10 or less, preferably 0.2 or more, 0.4 or more, 0.6 or more, or 0.8 or more, and preferably 5 or less, 4 or less, 2 or less, 1.5 or less, or 1.2 or less. When the ratio of the intensities of the peaks attributable to the CO stretching vibration and the OH stretching vibration on the surface of the first modified section is within the above numerical range, moisture components contained in the outside air, etc., are easily bonded to the CO groups and OH groups on the surface of the first modified section. This makes it possible to effectively prevent moisture components contained in the outside air, etc., from penetrating into the wavelength conversion member.

[0095] The barrier layer has a first modified portion on its end surface, and the region other than the first modified portion is an unmodified unmodified portion. The unmodified portion may be, for example, a region to which energy to form the first modified portion has not been applied. The content of functional groups in the unmodified portion (also referred to as the first unmodified portion), which is an unmodified region of the barrier layer, may be less than the content of functional groups in the first modified portion. That is, the ratio of the content of functional groups in the first modified portion to the content of functional groups in the unmodified portion may be greater than 1. The unmodified portion may be a region separated from the end surface of the barrier layer by a predetermined distance in a direction parallel to the main surface of the barrier layer, for example, a region separated from the end surface by 5 mm or more, preferably 10 mm or more, or 20 mm or more. The unmodified portion may also be the end surface of the barrier layer before forming the individual laminates using laser light in the manufacturing method described below. The first modified portion may be a region separated from the end surface of the barrier layer by 10 μm or less, preferably 9 μm or less, in a direction parallel to the main surface of the barrier layer.

[0096] The content of functional groups in the first modified section and the first non-modified section can be evaluated by measuring the infrared absorption spectrum as described above. Therefore, in the infrared absorption spectrum, the ratio of the peak intensity corresponding to the hydroxy group in the first modified section to the peak intensity corresponding to the hydroxy group in the first non-modified section may be greater than 1, preferably 1.03 or more, 1.05 or more, or 1.1 or more, and may be 20 or less, 10 or less, 5 or less, 2 or less, or 1.2 or less. Furthermore, in the infrared absorption spectrum, the ratio of the peak intensity corresponding to the carbonyl group in the first modified section to the peak intensity corresponding to the carbonyl group in the first non-modified section may be greater than 1, preferably 1.1 or more, 1.2 or more, or 1.25 or more, and may be 20 or less, 10 or less, 5 or less, 2 or less, or 1.5 or less. Here, the peak intensity corresponding to a hydroxy group may be the intensity ratio of the peak attributable to OH stretching vibration relative to the peak intensity attributable to CH stretching vibration, as described above, and the peak intensity corresponding to a carbonyl group may be the intensity ratio of the peak attributable to CO stretching vibration relative to the peak intensity attributable to CH stretching vibration.

[0097] The first modified portion may be, for example, a thermally denatured product of the thermoplastic resin that constitutes the barrier layer. It is thought that the first modified portion is formed by forming the end surface of the laminate using laser light, as in the method for producing a wavelength conversion member described below, whereby the thermoplastic resin that constitutes the barrier layer is thermally denatured. The first modified portion may be formed on at least a part of the end surface of the barrier layer, or may be formed on the entire end surface of the barrier layer.

[0098] The wavelength conversion layer constituting the laminate may have a second modified region on at least a portion of its end surface. The second modified region may have at least one oxygen-containing functional group (hereinafter simply referred to as a functional group) selected from the group consisting of a carboxy group, a hydroxy group, a carbonyl group, etc., on its surface. The presence of the functional group on the surface of the second modified region can be identified, for example, by measuring the infrared absorption spectrum of the surface of the second modified region, as with the surface of the first modified region. The second modified region can be formed, for example, by applying energy to the wavelength conversion layer.

[0099] The content of functional groups in the second modified region can be evaluated, for example, by measuring the infrared absorption spectrum of the surface of the second modified region. Specifically, for example, a peak attributed to CH stretching vibration (for example, a peak at a wave number of 2957 cm －１ ) intensity I ２ ＣＨ The intensity I of the peak assigned to the CO stretching vibration is ２ ＣＯ The ratio (I ２ ＣＯ / I ２ ＣＨ ), the intensity of the peak assigned to the OH stretching vibration I ２ ＯＨ The ratio (I ２ ＯＨ / I ２ ＣＨ ) on the surface of the second modified portion, the content of each functional group can be evaluated. ２ ＣＯ / I ２ ＣＨ) may be, for example, 0.1 or more and 30 or less, preferably 0.2 or more, 0.4 or more, 0.8 or more, 1 or more, or 1.2 or more, and may be preferably 15 or less, 10 or less, 6 or less, 4 or less, or 2 or less. In addition, the ratio (I ２ ＯＨ / I ２ ＣＨ ) may be, for example, 0.1 or more and 10 or less, preferably 0.2 or more or 0.3 or more, and preferably 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.8 or less, or 0.6 or less. When the intensity ratio of the peaks attributable to the CO stretching vibration and the OH stretching vibration on the surface of the second modified section is within the above numerical range, moisture components contained in the outside air, etc. are easily bonded to the CO groups and OH groups on the surface of the second modified section. This is thought to make it possible to effectively prevent moisture components contained in the outside air, etc. from penetrating into the wavelength conversion member.

[0100] The wavelength conversion layer has a second modified portion on its end surface, and the region other than the second modified portion is an unmodified unmodified portion. The unmodified portion may be, for example, a region to which energy to form the second modified portion has not been applied. The content of functional groups in the unmodified region of the wavelength conversion layer (also referred to as the second unmodified portion) may be less than the content of functional groups in the second modified portion. That is, the ratio of the content of functional groups in the second modified portion to the content of functional groups in the unmodified portion may be greater than 1. The second unmodified portion may be a region separated from the end surface of the wavelength conversion layer by a predetermined distance in a direction parallel to the main surface of the wavelength conversion layer, for example, a region separated from the end surface by 5 mm or more, preferably 10 mm or more, or 20 mm or more. The second unmodified portion may also be the end surface of the wavelength conversion layer before forming the individual laminate using laser light in the manufacturing method described below. The second modified portion may be a region located at a distance of 10 μm or less, preferably 9 μm or less, from the end face of the wavelength conversion layer in a direction parallel to the main surface of the wavelength conversion layer.

[0101] The content of functional groups in the second modified portion and the second non-modified portion can be evaluated by measuring the infrared absorption spectrum as described above. Therefore, in the infrared absorption spectrum, the ratio of the peak intensity corresponding to the hydroxy group in the second modified portion to the peak intensity corresponding to the hydroxy group in the second non-modified portion may be greater than 1, preferably 1.2 or more, 2 or more, 2.4 or more, 2.6 or more, 2.8 or more, or 3 or more, and may be 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. Furthermore, in the infrared absorption spectrum, the ratio of the peak intensity corresponding to the carbonyl group in the second modified portion to the peak intensity corresponding to the carbonyl group in the second non-modified portion may be greater than 1, preferably 1.2 or more, 1.6 or more, 2 or more, or 2.4 or more, and may be 8 or less, 7 or less, 6 or less, 5 or less, or 4 or less. Here, the peak intensity corresponding to a hydroxy group may be the intensity ratio of the peak attributable to OH stretching vibration relative to the peak intensity attributable to CH stretching vibration, as described above, and the peak intensity corresponding to a carbonyl group may be the intensity ratio of the peak attributable to CO stretching vibration relative to the peak intensity attributable to CH stretching vibration.

[0102] The second modified portion may be, for example, a thermally denatured product of the cured resin constituting the wavelength conversion layer. It is considered that, as in the method for producing a wavelength conversion member described below, the end surface of the laminate is formed using laser light, and the cured resin constituting the wavelength conversion layer is thermally denatured to form the second modified portion. The second modified portion may be formed on at least a portion of the end surface of the wavelength conversion layer, or may be formed on the entire end surface of the wavelength conversion layer.

[0103] In the laminate, at least a portion of the second modified region may be exposed at the end surface of the laminate. The average thickness of the second modified region exposed at the end surface of the laminate may be 10% to 80% of the average thickness of the wavelength conversion layer, preferably 20% to 70% or 20% to 60%. Here, the thickness of the second modified region refers to the height of the second modified region in the stacking direction of the laminate. The ratio of the average thickness of the second modified region exposed at the end surface of the laminate to the average thickness of the wavelength conversion layer is calculated as a percentage of the arithmetic mean of the values ​​measured at any three positions of the exposed second modified region and divided by the average thickness of the wavelength conversion layer. In one aspect, the end surface of the laminate may be formed by stacking the first modified region, the second modified region, and the first modified region in this order.

[0104] In one embodiment, the first modified portion may cover at least a portion of the boundary between the barrier layer and the wavelength conversion layer at the end surface of the laminate. By covering the boundary between the barrier layer and the wavelength conversion layer with the first modified portion, a wavelength conversion member can be configured in which fading from the end surface is more effectively suppressed. The length of the boundary covered by the first modified portion may be 1% or more of the total length of the boundary at the end surface of the laminate, and may be preferably 10% or more, or 100%.

[0105] When the first modified portion covers the boundary between the barrier layer and the wavelength conversion layer, the first modified portion may further cover a portion of the wavelength conversion layer. The covered portion of the wavelength conversion layer may be a portion of the second modified portion or an unmodified portion of the wavelength conversion layer. The coverage of the portion of the wavelength conversion layer covered by the first modified portion may be, for example, 5% to 50%, preferably 5% to 30%, or 5% to 10%, as a ratio of the area of ​​the wavelength conversion layer calculated from the length of the end face of the laminate and the average thickness of the wavelength conversion layer.

[0106] One embodiment of the end portion of a wavelength conversion member including a laminate will be described with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing one embodiment of a cross section at the end portion of a wavelength conversion member 100, taken along a cross section parallel to the stacking direction. The wavelength conversion member 100 is composed of a wavelength conversion layer 20 and barrier layers 10 disposed on each of the two main surfaces of the wavelength conversion layer 20. At the end portion of the wavelength conversion member 100, a first modified region 18 is formed at the end portion of the barrier layer 10, and a second modified region 28 is formed at the end portion of the wavelength conversion layer 20. In the first modified region 18, for example, a thickened region 16 formed by an increased thickness of the barrier layer and a bubble region 12 formed by gas generated by laser light irradiation are formed.

[0107] The thickened portion 16 is formed by expanding the main surface of the barrier layer opposite to the wavelength conversion layer side in the stacking direction. The formation of the thickened portion 16 at the end of the wavelength conversion member 100 makes it possible to further reduce the water vapor permeability to the end side. The end of the laminate has routes for moisture to enter from the stacking direction and from a direction perpendicular to the stacking direction, making it an area that is easily exposed to moisture, but the formation of the thickened portion 16 makes it possible to effectively suppress moisture intrusion.

[0108] Furthermore, by forming the bubble portions 12 in the first modified section 18, even if stress is applied to the end of the wavelength conversion member 100, the buffering effect of the bubble portions 12 can prevent peeling between the wavelength conversion layer 20 and the barrier layer 10. Stress may be unintentionally applied to the end of the wavelength conversion member, for example, during transportation of the wavelength conversion member or installation in a backlight device, etc. Furthermore, by forming the bubble portions 12, a refractive index difference is created in the barrier layer, which may improve the light scattering properties of the wavelength conversion member.

[0109] The barrier layer at the end of the wavelength conversion member 100 may have a protrusion 14 formed thereon, protruding outward from the wavelength conversion layer. The protrusion 14 may be formed as part of the first modified section 18. Forming a protrusion at the end of the wavelength conversion member makes it possible to suppress direct stress load on the wavelength conversion layer due to interference between the wavelength conversion member and the housing of a backlight device, for example, when incorporating the wavelength conversion member into a backlight device, etc. This suppresses peeling between the wavelength conversion layer and the barrier layer, making it possible to more effectively suppress the intrusion of moisture and the like into the wavelength conversion layer. Furthermore, when an end surface coating layer is disposed on the end surface of the laminate, the contact area between the end surface of the laminate and the end surface coating layer is increased, further improving the adhesion of the end surface coating layer to the laminate.

[0110] The wavelength conversion member may further include an end surface covering layer that covers the end surface of the laminate. By including the end surface covering layer, fading from the end surface of the wavelength conversion member can be more effectively suppressed. The end surface covering layer may be a member having gas barrier properties formed, for example, containing an inorganic material. The end surface covering layer may be a member that suppresses the intrusion of moisture, oxygen, etc. from the end surface of the laminate. The end surface covering layer may be arranged so as to cover at least a portion of the end surface of the laminate, and preferably may be arranged so as to cover the entire periphery of the end surface of the laminate.

[0111] The end face covering layer may include a film made of an inorganic compound such as an oxide, nitride, oxynitride, or carbide, as exemplified above as the inorganic layer. Among these, silicon compounds such as silicon oxide, silicon nitride, silicon oxynitride, and silicon carbide may be used from the viewpoints of gas barrier properties and a high refractive index. The end face covering layer may be made of one type of inorganic compound, or may be made of two or more types of inorganic compounds. The end face covering layer may also include a cured resin layer made of a resin composition containing at least one functional material selected from the group consisting of a moisture remover (moisture scavenger), an oxygen remover (oxygen scavenger), an antioxidant, and the like, as described below. The resin composition may include, for example, an epoxy resin as a base material.

[0112] When the end surface covering layer includes a film made of an inorganic compound, the average thickness of the film in the direction perpendicular to the end surface of the laminate may be, for example, 0.05 μm to 1 μm, preferably 0.05 μm to 0.9 μm, or 0.1 μm to 0.8 μm. When the end surface covering layer includes a cured resin layer, the average thickness of the cured resin layer may be, for example, 5 μm to 1000 μm, preferably 200 μm to 800 μm, or 300 μm to 650 μm. The thickness of the end surface covering layer is, for example, the distance between the outermost end of the end surface covering layer and the end surface of the laminate when viewed from above. When the end surface covering layer includes a cured resin layer, the thickness of the cured resin layer may be uniform along the stacking direction of the wavelength conversion member, or may increase or decrease in one direction.

[0113] The end surface covering layer may be formed by a known method depending on the material used. When the end surface covering layer includes a film made of an inorganic compound, the film made of the inorganic compound can be formed by, for example, a plasma CVD method such as CCP-CVD or ICP-CVD, a sputtering method such as magnetron sputtering or reactive sputtering, a vacuum deposition method, or a vapor phase deposition method. When the end surface covering layer includes a cured resin layer, the cured resin layer can be formed by applying a desired resin composition to the end surface of the laminate and then curing it.

[0114] FIG. 8 is a schematic cross-sectional view of a wavelength conversion member 110 illustrating an example of an end face coating layer. The end face coating layer 30 shown in FIG. 8 is a cured resin layer made of a resin composition containing an epoxy resin and at least one functional material selected from the group consisting of a moisture remover (moisture scavenger), an oxygen remover (oxygen scavenger), and an antioxidant. In FIG. 8 , the end face coating layer 30 is provided on both opposing end faces of the wavelength conversion member 110. The end face coating layer 30 may be provided on the entire end face surrounding the outer periphery of the wavelength conversion member 110. On the end face of the wavelength conversion member 110, the end face coating layer 30 is disposed across the two barrier layers 10 and the wavelength conversion layer 20, and covers at least the boundary between the upper barrier layer 10 and the wavelength conversion layer 20 and the boundary between the lower barrier layer 10 and the wavelength conversion layer 20. This more effectively prevents moisture and other contaminants from penetrating through the boundary between the barrier layer 10 and the wavelength conversion layer 20. The upper end of the end covering layer 30 is located higher in the height direction than the boundary between the barrier layer 10 and the wavelength conversion layer 20 located above. In the end covering layer 30 shown in FIG. 8 , as indicated by the opposing arrows, the upper end of the end covering layer 30 is located between the upper surface of the barrier layer 10 and the upper surface of the wavelength conversion layer 20 located above, and does not reach the upper surface of the barrier layer 10 located above. By separating the upper end of the end covering layer 30 from the upper surface of the barrier layer 10, it is possible to prevent the end covering layer 30 from unintentionally creeping up onto the upper surface of the barrier layer 10 when arranging the end covering layer 30, thereby preventing a decrease in brightness at the upper end of the stack. Furthermore, the lower end of the end covering layer 30 is located approximately flush with the lower surface of the barrier layer 10 located below. Furthermore, the end covering layer 30 has an inclined surface 32 that is inclined relative to the upper surface of the barrier layer 10 located above. The inclined surface 32 may be flat or may include a curved surface. In addition, when the wavelength conversion member includes an end surface covering layer that covers the end surface of the laminate, the end surface of the laminate may be a surface formed by cutting by irradiation with laser light, or may be a surface that is not cut by irradiation with laser light. Preferably, the end surface of the laminate may be a surface formed by cutting by irradiation with laser light.

[0115] The wavelength conversion member may include a laminate including other layers as needed, such as a hard coat layer, an optical compensation layer, a transparent conductive layer, an adhesion-imparting layer, and an intermediate layer described below.

[0116] The laminate may include an intermediate layer disposed between the wavelength conversion layer and the barrier layer. The intermediate layer may be made of a material having good adhesion to both the wavelength conversion layer and the barrier layer. This can prevent moisture and other contaminants from penetrating through the boundary between the intermediate layer and the wavelength conversion layer, the boundary between the intermediate layer and the barrier layer, etc. The intermediate layer may contain, as a base material, a cured resin having a composition similar to that of the cured resin exemplified in the description of the wavelength conversion layer.

[0117] The intermediate layer may further contain at least one functional material in addition to the curable resin, such as a moisture remover (moisture scavenger), an oxygen remover (oxygen scavenger), an antioxidant, etc., and may contain at least one selected from the group consisting of these.

[0118] Examples of moisture removers include oxides of Group 2 elements such as magnesium oxide and calcium oxide, hydrotalcite, aluminosilicates (e.g., zeolites), and silicon oxides (e.g., silica gel). Here, the hydrotalcite may be a compound having a composition represented by the following formula (3): [M ３ １－ｘ M ４ ｘ (OH) ２ ] ｘ＋ [A ｎ－ ｘ / ｎ ・mH ２ O] ｘ－ (3)

[0119] In formula (3), M ３ is Mg ２＋ , Mn ２＋ , Fe ２＋ , Co ２＋ , Ni ２＋ , Cu ２＋ , Zn ２＋ It represents a divalent metal ion such as M ４ is Fe ３＋ , Cr ３＋ , Co３＋ , In ３＋ It indicates a trivalent metal ion such as A. ｎ－ OH － , F － , Cl － ,Br － , NO ３ － , CO ３ ２－ , S.O. ４ ２－ , Fe(CN) ６ ３－ , C.H. ３ COO － , oxalate, salicylate, etc., where x satisfies the relationship 0<x≦0.33, and m is a positive number.

[0120] Examples of oxygen removers include ceria-zirconia solid solution (CZ solid solution), etc. Examples of antioxidants include ascorbic acid, catechin, dibutylhydroxytoluene, tocopherol, butylhydroxyanisole, etc.

[0121] The content of the functional material in the intermediate layer may be, for example, 0.1 parts by mass to 20 parts by mass, preferably 0.1 parts by mass to 15 parts by mass, or 0.1 parts by mass to 2 parts by mass, relative to 100 parts by mass of the cured resin. By setting the content of the functional material in the intermediate layer within the above range, it is possible to suppress the intrusion of moisture contained in the outside air, etc., while suppressing a decrease in the luminous efficiency of the wavelength conversion member caused by the functional material.

[0122] The thickness of the intermediate layer may be, for example, 10 μm or more and 100 μm or less, preferably 20 μm or more or 30 μm or more, and preferably 70 μm or less or 40 μm or less.

[0123] 2. Method for manufacturing wavelength conversion member A method for manufacturing a wavelength conversion member may include: a first step of preparing a laminate sheet including a wavelength conversion layer containing quantum dots and two barrier layers laminated on one main surface and the other main surface of the wavelength conversion layer, and a second step of cutting the laminate sheet into individual laminates by irradiating the laminate sheet with laser light that intersects the main surface of the laminate sheet to obtain individual laminates. The laser light irradiation in the second step may have a frequency of 5 kHz to 30 kHz, a scanning speed of 50 mm / s to 100 mm / s, and a laser light output of 3.4 W to 100 W.

[0124] By cutting the laminate sheet by irradiating it with laser light into individual pieces to form a laminate, it is possible to suppress fading from the edge of the wavelength conversion member including the laminate. This can be thought of as being because, for example, cutting the laminate sheet by irradiating it with laser light forms a first modified region derived from the barrier layer and a second modified region derived from the wavelength conversion layer on the edge surface of the laminate.

[0125] In the first step, a laminate sheet is prepared, comprising a wavelength conversion layer containing quantum dots and two barrier layers laminated on one main surface and the other main surface of the wavelength conversion layer, respectively. The laminate sheet can be produced, for example, as follows: The photocurable composition described above is applied to the surface of a continuously conveyed film-like barrier layer (e.g., a barrier film) to form a first composition layer. Examples of methods for applying the photocurable composition include gravure coating, die coating, curtain coating, extrusion coating, rod coating, and roll coating. Next, a film-like barrier layer (e.g., a barrier film) is laminated onto the first composition layer. This results in a laminate sheet precursor in which the barrier layer, the first composition layer, and the barrier layer are laminated in this order. Next, the first composition layer is cured by irradiating it with light from either barrier layer side to form a wavelength conversion layer, thereby obtaining a laminate sheet in which the barrier layer, the wavelength conversion layer, and the barrier layer are laminated in this order. If necessary, the first composition layer may be subjected to a drying treatment, heat treatment, or the like before irradiating it with light. The wavelength conversion layer and the barrier layer constituting the laminate sheet are as described above in detail.

[0126] In the second step, the laminate sheet is cut by irradiating it with laser light that intersects the main surface of the laminate sheet to obtain individual laminates. The frequency of the laser light in the second step may be, for example, 5 kHz to 30 kHz, preferably 5 kHz to 28 kHz, or 5 kHz to 25 kHz. The laser light output may be, for example, 3.4 W to 100 W, preferably 5 W to 50 W, or 5 W to 30 W. Examples of laser light include a carbon dioxide laser, a UV laser, and a YAG laser, and a carbon dioxide laser may be used.

[0127] Cutting of a laminate sheet by irradiation with laser light is carried out by scanning the laser light across the main surface of the laminate sheet. The scanning speed of the laser light may be, for example, 50 mm / s to 100 mm / s, preferably 60 mm / s to 100 mm / s, or 70 mm / s to 100 mm / s. The number of scans of the laser light per cut surface may be, for example, 1 to 5, preferably 1 to 2.

[0128] The laser beam may be irradiated onto the laminate sheet while discharging an inert gas near the laser beam irradiation position. Discharging the inert gas can prevent contamination of the laminate by decomposition gases. Examples of the inert gas used for discharging include rare gases such as argon and nitrogen gas, and nitrogen gas may be used. The discharge rate of the inert gas may be, for example, 100 ml / s or more and 1000 ml / s or less, and preferably 100 ml / s or more and 500 ml / s or less.

[0129] In the second step, the laminate sheet to be irradiated with laser light may be held in contact with the support, or may be held in a state where at least the laser light irradiation position is separated from the support. From the viewpoint of the processability of the laminate sheet, the laminate sheet may be held in a state where at least the laser light irradiation position is separated from the support. That is, the laser light irradiation may be carried out by providing a space on the main surface of the laminate sheet opposite to the main surface irradiated with the laser light at the laser light irradiation position. As a method for holding the laser light irradiation position separated from the support, for example, the entire laminate sheet portion including the region of the singulated laminate may be held separated from the support, or a recess, notch, etc. may be provided in the support at the position corresponding to the laser light irradiation position, and a space may be provided on the opposite side of the laser light irradiation position.

[0130] In the individual laminates formed by cutting the laminate sheet by irradiating the laser beam, the cut surfaces intersecting the main surfaces are the end surfaces. The cut surfaces that become the end surfaces of the laminate may be, for example, substantially perpendicular to the main surfaces of the laminate. The cut surfaces may also be provided so as to surround the outer edge of the laminate. The outer edge of the laminate may be surrounded by four planar cut surfaces, or may be surrounded by a cut surface including at least one curved cut surface.

[0131] At the cut surface of the laminate, at least part of the end faces of the two barrier layers constituting the laminate and at least part of the end face of the wavelength conversion layer are exposed. By forming the cut surface so that at least part of the end face of the wavelength conversion layer is exposed, fading of the wavelength conversion member from its end over time is suppressed. Details of the exposed state of the end face of the wavelength conversion layer at the cut surface of the laminate are as described above.

[0132] At the cut surface of the laminate, a first modified region may be formed on at least a portion of the end surface of the barrier layer. The first modified region may have at least one oxygen-containing functional group selected from the group consisting of a carboxy group, a hydroxy group, and a carbonyl group on its surface. The amount of oxygen-containing functional groups on the surface of the first modified region is as described above. Furthermore, the density of oxygen-containing functional groups on the surface of the first modified region may be greater than the density of oxygen-containing functional groups on the end surface of the barrier layer of the laminate sheet before cutting. That is, the ratio of the density of oxygen-containing functional groups on the surface of the first modified region to the density of oxygen-containing functional groups on the end surface of the barrier layer of the laminate sheet before cutting may be greater than 1, preferably 5 or greater. Details of the ratio of the density of oxygen-containing functional groups on the surface of the first modified region to the density of oxygen-containing functional groups on the end surface of the barrier layer of the laminate sheet before cutting are as described above.

[0133] At the cut surface of the laminate, the first modified portion may cover the boundary between the barrier layer and the wavelength conversion layer. Details of the covering state of the first modified portion at the cut surface of the laminate are as described above.

[0134] At the cut surface of the laminate, a second modified region may be formed on at least a part of the end surface of the wavelength conversion layer. The second modified region may have at least one oxygen-containing functional group selected from the group consisting of a carboxy group, a hydroxy group, and a carbonyl group on its surface. The amount of oxygen-containing functional groups on the surface of the second modified region is as described above. Furthermore, the density of oxygen-containing functional groups on the surface of the second modified region may be greater than the density of oxygen-containing functional groups on the end surface of the wavelength conversion layer of the laminate sheet before cutting. That is, the ratio of the density of oxygen-containing functional groups on the surface of the second modified region to the density of oxygen-containing functional groups on the end surface of the wavelength conversion layer of the laminate sheet before cutting may be greater than 1, preferably 5 or more. Details of the ratio of the density of oxygen-containing functional groups on the surface of the second modified region to the end surface of the wavelength conversion layer of the laminate sheet before cutting are as described above.

[0135] The barrier layer of the laminate sheet may contain a thermoplastic resin as described above. When the barrier layer contains a thermoplastic resin, the first modified portion formed on the cut surface of the laminate may contain a thermally denatured product of the thermoplastic resin formed when the laminate sheet is cut with laser light. Furthermore, the wavelength conversion layer of the laminate sheet may contain a cured resin of a photocurable composition as described above. When the wavelength conversion layer contains a cured resin, the second modified portion formed on the cut surface of the laminate may contain a thermally denatured product of the cured resin formed when the laminate sheet is cut with laser light.

[0136] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0137] Reference Example 1: Preparation of a laminated sheet Preparation of nanoparticle precursor As raw materials, 25.2 g of formamidinium hydrobromide (FABr; manufactured by Tokyo Chemical Industry Co., Ltd.) and 25.2 g of lead (II) bromide (PbBr ２Stream Chemicals): 74.2 g, 10 mm diameter zirconia balls YTZ (yttria-stabilized zirconia; AS ONE Corporation): 22.6 g, and 2 mm diameter zirconia balls YTZ (yttria-stabilized zirconia; AS ONE Corporation): 5.6 g were placed in an alumina pot. The alumina pot containing the raw materials was attached to a ball mill rotating stand (AV-1; AS ONE Corporation), and the raw materials were mixed for 48 hours at a rotation speed of 160 rpm. Next, 50 g of hexane as an organic solvent was added to the alumina pot containing the raw materials, and the raw materials were mixed for an additional 3 hours at a rotation speed of 160 rpm. After the raw material mixing was completed, the mixture obtained by suction filtration was passed through a nylon mesh with a mesh size of 300 μm to remove the zirconia balls YTZ, and a slurry-like first mixture was obtained. This first mixture was filtered under suction and then naturally dried in the air for 24 hours to obtain nanoparticle precursors.

[0138] The nanoparticle precursor is [(NH ２ ) ２ CH]PbBr ３ (hereinafter referred to as "FAPbBr ３ The nanoparticle precursor had a composition represented by the formula (1). The nanoparticle precursor was orange in color. The nanoparticle precursor did not emit light even when irradiated with light having a wavelength of 450 nm.

[0139] Measurement of X-ray diffraction pattern The XRD pattern of the nanoparticle precursor obtained above was measured by X-ray diffraction (XRD) using CuKα radiation. Using an X-ray diffractometer (MiniFlex, manufactured by Rigaku Corporation), the XRD pattern showing the diffraction intensity (Intensity) versus the diffraction angle (2θ) was measured under the following conditions. The results are shown in Figure 1.

[0140] Figure 1 shows the XRD pattern of the nanoparticle precursor (top) and the FAPbBr nanoparticles with an orthorhombic crystal structure registered in the ICSD (Inorganic Crystal Structure Database). ３ As shown in FIG. 1, the peak positions of the XRD pattern of the nanoparticle precursor are the same as those of FAPbBr registered in the ICSD. ３The XRD pattern of the nanoparticle precursor confirmed that the nanoparticle precursor had an orthorhombic crystal structure.

[0141] Preparation of nanoparticles Nanoparticle precursor: 3.15 g, organic solvents oleylamine (Tokyo Chemical Industry Co., Ltd.): 0.94 g, octadecyldimethyl(3-sulfopropyl)ammonium hydroxide (SBE-18; Merck): 0.31 g, and toluene (Fujifilm Wako Pure Chemical Industries, Ltd.): 101 g, and zirconia ball YTZ (yttria-stabilized zirconia; AS ONE Corporation): 422 g of 0.2 mm diameter as a dispersion medium were added to a wet fine bead mill grinder / disperser (Labostar Mini; Ashizawa Finetech Co., Ltd.), and stirred for 1 hour at a peripheral speed of 14 m / s and a rotation speed of 4456 rpm. The mixture obtained by stirring was passed through a nylon mesh with a mesh size of 25 μm by suction filtration to remove the zirconia ball YTZ and unground coarse nanoparticle precursor, and a slurry-like second mixture was obtained. The second mixture was placed in a container and centrifuged at 5,000 rpm for 10 minutes using a centrifuge (CN-2060; rotation radius 94 mm; AS ONE Corporation) to settle coarse particles and recover the supernatant. The resulting supernatant was filtered through a syringe filter with a pore size of 0.2 μm to obtain a dispersion containing nanoparticles. The content of nanoparticles in the dispersion was 0.57% by mass.

[0142] When the dispersion liquid containing the nanoparticles was irradiated with light of 450 nm, the dispersion liquid containing the nanoparticles emitted light.

[0143] Transmission Electron Microscope (TEM) Observation of Nanoparticles The nanoparticles in the solution were observed using a transmission electron microscope (TEM; H-7650; manufactured by Hitachi High-Technologies Corp.) Figure 2 shows a TEM image of the nanoparticles.

[0144] Average Particle Size of Nanoparticles The average particle size of nanoparticles was measured from TEM images magnified from 80,000 to 200,000 times the nanoparticle size. Here, a Hi-Res Carbon HRC-C10 STEM Cu100P grid (manufactured by Oken Shoji Co., Ltd.) was used as the TEM grid. The obtained nanoparticles were spherical or polygonal in shape. The average particle size was determined by selecting three or more TEM images, measuring the particle sizes of all measurable nanoparticles contained in these TEM images, and calculating the arithmetic mean value. Specifically, the average particle size of nanoparticles was determined by measuring the particle size of each nanoparticle as the length of the longest line segment connecting any two points on the periphery of the particle observed in the TEM image and passing through the center of the particle, and then calculating the arithmetic mean value of the particle sizes of more than 100 nanoparticles. The average particle size of the obtained nanoparticles was 11.2 nm.

[0145] Preparation of nanoparticle IBOA dispersion: 5.0 g of a dispersion containing nanoparticles (nanoparticle content 0.57% by mass) was mixed with 2.03 g of isobornyl acrylate (IBOA; manufactured by Tokyo Chemical Industry Co., Ltd.) as a radical polymerizable monomer to prepare a solution. The pressure of this solution was reduced to 10 mbar using an evaporator, and the toluene was evaporated over 24 hours while heating at 30°C to obtain a nanoparticle IBOA dispersion. The nanoparticle content in the dispersion was 1.4% by mass.

[0146] Luminescence Properties The luminescence properties of the nanoparticle IBOA dispersion were measured. Using a quantum efficiency measurement device (QE-2100, manufactured by Otsuka Electronics Co., Ltd.), the nanoparticle IBOA dispersion was irradiated with light having an emission peak wavelength of 450 nm, and the emission spectrum was measured at room temperature (25°C). The nanoparticle IBOA dispersion was diluted with a solvent (IBOA) so that the absorbance at 450 nm was 0.15. From the obtained emission spectrum, the internal quantum efficiency (%), emission peak wavelength (nm), and half-width (nm) of the emission spectrum were determined. The internal quantum efficiency (%) is the proportion of photons converted to emission out of the photons absorbed by the nanoparticles, and was calculated by dividing the number of emitted photons (%) by the number of absorbed photons (%). The luminescence properties of the nanoparticle IBOA dispersion are shown in Table 1.

[0147]

[0148] The nanoparticle IBOA dispersion had a high internal quantum efficiency of 92%, a narrow half-value width of 24 nm, and excellent color purity. It also emitted green light by absorbing light with a peak wavelength of 450 nm and emitting light with a peak wavelength of 518 nm.

[0149] An acrylic monomer mixture was obtained by mixing 0.7 g of dicyclopentanyl acrylate (FA-513AS; manufactured by Showa Denko Materials Co., Ltd.), 0.3 g of EO-modified bisphenol A dimethacrylate (FA-321M; manufactured by Showa Denko Materials Co., Ltd.), and 0.01 g of a photopolymerization initiator, 2,4,6-trimethylbenzoyl)phosphine oxide (TPO; manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). 0.23 g of the nanoparticle IBOA dispersion obtained above and 1.0 g of the acrylic monomer mixture were mixed in a planetary centrifugal mixer (Mazerus Star; manufactured by Kurabo Industries, Ltd.) to prepare a photocurable composition.

[0150] Barrier films (TBF1004, manufactured by i-components) were prepared as the two barrier layers. A photocurable composition was applied between the two barrier layers using a roll-to-roll coater, and then irradiated with ultraviolet light from a UV irradiator to initiate a polymerization reaction of the monomers and cause curing, thereby producing a laminated sheet in which the barrier films were adhered to both main surfaces of a 50 μm-thick wavelength conversion layer.

[0151] Example 1 The laminate sheet obtained above was cut using a carbon dioxide laser irradiator at a frequency of 25 kHz, an output of 7.5 W, a scanning speed of 70 mm / s, and two passes per cross section to cut out a rectangular laminate (□25 mm) with a side of 25 mm, to produce the wavelength conversion member of Example 1.

[0152] Example 2 A wavelength conversion member of Example 2 was produced in the same manner as in Example 1, except that the output of the carbon dioxide laser irradiator was changed to 15 W.

[0153] Example 3 A wavelength conversion member of Example 3 was produced in the same manner as in Example 1, except that the output of the carbon dioxide laser irradiator was changed to 30 W.

[0154] Comparative Example 1 A wavelength conversion member of Comparative Example 1 was produced by cutting the laminate sheet obtained above into a rectangular laminate (25 mm square) with one side being 25 mm using a cutter.

[0155] Evaluation 1. Scanning Microscope Observation SEM images were obtained as backscattered electron images of the cut surfaces of the wavelength conversion members produced in Comparative Example 1 and Example 3 using a scanning electron microscope (SEM; JSM-IT200 manufactured by JEOL Ltd.) under conditions of an acceleration voltage of 5 kV and a probe current of 50 μA. A backscattered electron image of the cut surface of the wavelength conversion member of Comparative Example 1 cut by a cutter is shown in FIG. 4, and a backscattered electron image of the cut surface of the wavelength conversion member of Example 3 cut by a laser is shown in FIG.

[0156] As shown in Fig. 4 , interfacial peeling was observed between the wavelength conversion layer and each barrier layer on the cut surface of the wavelength conversion member produced in Comparative Example 1. On the other hand, as shown in Fig. 5 , interfacial peeling was suppressed between the wavelength conversion layer and each barrier layer on the cut surface of the wavelength conversion member produced in Example 3.

[0157] 2. Fluorescence Microscope Observation The wavelength conversion members produced in Comparative Example 1 and Example 3 were dry diced to expose the cut edges to prepare samples. The cross sections of the edges of the prepared samples were observed using a fluorescence microscope (Olympus Corporation). A fluorescence microscope image of the cross section of the edge of the wavelength conversion member of Comparative Example 1 cut by a cutting machine is shown in FIG. 6 , and a fluorescence microscope image of the cross section of the edge of the wavelength conversion member of Example 3 cut by a laser is shown in FIG. 7 .

[0158] A comparison of FIG. 6 and FIG. 7 reveals that the first modified region and the second modified region are present in the cross section of the wavelength conversion member of Example 3.

[0159] 3. Infrared Absorption Spectrum A sample having a modified cut surface was prepared by cutting the barrier film, which was the barrier layer used in Reference Example 1, under the laser irradiation conditions of Example 3. The infrared absorption spectra of the modified cut surface (first modified portion) of the prepared sample and an unmodified cut surface (first unmodified portion) formed by cutting with a cutter at a position 20 mm from the cut surface were measured by the attenuated total reflection (ATR) method using a Fourier transform infrared spectrophotometer (manufactured by Thermo Fisher Scientific).

[0160] From the obtained infrared absorption spectrum, the peak intensity (peak wavelength 1725 cm ) attributed to the CO stretching vibration in the first modified region, which is the cut surface of the prepared sample formed by the laser, was －１ ;I １ ＣＯ ), the peak intensity attributed to OH stretching vibration (peak wavelength 3300 cm －１ ;I １ ＯＨ ) and the peak intensity attributed to CH stretching vibration (peak wavelength 2957 cm －１ ;I １ ＣＨ ) were measured, and the peak intensity ratio (I １ ＣＯ / I １ ＣＨ ), and the peak intensity ratio assigned to OH stretching vibration (I １ ＯＨ / I １ ＣＨ ) were calculated. In addition, the peak intensity (peak wavelength 1725 cm) attributed to the CO stretching vibration in the first unmodified portion, which is the cut surface formed by the cutter, was calculated. －１ ;I ２ ＣＯ ), peak intensity product attributed to OH stretching vibration, peak wavelength 3300 cm －１ ;I ２ ＯＨ ) and the peak intensity attributed to CH stretching vibration (peak wavelength 2957 cm －１ ;I ２ ＣＨ ) were measured, and the peak intensity ratio (I ２ ＣＯ / I ２ ＣＨ ), and the peak intensity ratio assigned to OH stretching vibration (I ２ ＯＨ / I ２ ＣＨ ) were calculated. Furthermore, using these peak intensity ratios, the ratio of the peak intensity ratio attributable to the CO stretching vibration in the first modified region to the peak intensity ratio attributable to the CO stretching vibration in the first unmodified region (I １ ＣＯ / I ２ ＣＯ) and the ratio of the peak intensity ratio attributable to the OH stretching vibration in the first modified portion to the peak intensity ratio attributable to the OH stretching vibration in the first unmodified portion (I １ ＯＨ / I ２ ＯＨ The results are shown in Table 2.

[0161]

[0162] The acrylic monomer mixture prepared in Reference Example 1 was irradiated with ultraviolet light under the same conditions as in Reference Example 3 to obtain a cured product. The obtained cured product was cut under the laser irradiation conditions of Examples 2 and 3 to prepare samples having modified cut surfaces. The infrared absorption spectra of the modified cut surface (second modified portion) of the prepared sample and an unmodified cut surface (second unmodified portion) formed by cutting with a cutter at a position 20 mm from the cut surface were measured using a Fourier transform infrared spectrophotometer (manufactured by Thermo Fisher Scientific).

[0163] From the obtained infrared absorption spectrum, the peak intensity (peak wavelength 1725 cm) attributed to the CO stretching vibration in the modified cut surface (second modified portion) of the sample prepared under the laser irradiation conditions of Example 2 was －１ ;I ３ ＣＯ ), the peak intensity attributed to OH stretching vibration (peak wavelength 3300 cm －１ ;I ３ ＯＨ ) and the peak intensity attributed to CH stretching vibration (peak wavelength 2957 cm －１ ;I ３ ＣＨ ) were measured, and the peak intensity ratio (I ３ ＣＯ / I ３ ＣＨ ), and the peak intensity ratio assigned to OH stretching vibration (I ３ ＯＨ / I ２３ ＣＨ ) were calculated. In addition, the peak intensity (peak wavelength 1725 cm) attributed to the CO stretching vibration in the modified cut surface (second modified portion) of the sample prepared under the laser irradiation conditions of Example 3 was calculated. －１ ;I４ ＣＯ ), the peak intensity attributed to OH stretching vibration (peak wavelength 3300 cm －１ ;I ４ ＯＨ ) and the peak intensity attributed to CH stretching vibration (peak wavelength 2957 cm －１ ;I ４ ＣＨ ) were measured, and the peak intensity ratio (I ４ ＣＯ / I ４ ＣＨ ), and the peak intensity ratio assigned to OH stretching vibration (I ４ ＯＨ / I ４ ＣＨ ) were calculated. Furthermore, the peak intensity (peak wavelength 1725 cm) attributed to the CO stretching vibration in the unmodified cut surface (second unmodified portion) was calculated. －１ ;I ５ ＣＯ ), the peak intensity attributed to OH stretching vibration (peak wavelength 3300 cm －１ ;I ５ ＯＨ ) and the peak intensity attributed to CH stretching vibration (peak wavelength 2957 cm －１ ;I ５ ＣＨ ) were measured, and the peak intensity ratio (I ５ ＣＯ / I ５ ＣＨ ), and the peak intensity ratio assigned to OH stretching vibration (I ５ ＯＨ / I ５ ＣＨ ) was calculated. Furthermore, using these peak intensity ratios, the ratio of the peak intensity ratio attributable to the CO stretching vibration in the second modified region to the peak intensity ratio attributable to the CO stretching vibration in the second unmodified region (I ３ ＣＯ / I ５ ＣＯ , I ４ ＣＯ / I ５ ＣＯ) and the ratio of the peak intensity ratio attributable to the OH stretching vibration in the second modified portion to the peak intensity ratio attributable to the OH stretching vibration in the second unmodified portion (I ３ ＯＨ / I ５ ＯＨ , I ４ ＯＨ / I ５ ＯＨ The results are shown in Table 3.

[0164]

[0165] 4. High-Temperature, High-Humidity Storage Test The following evaluation was performed on the wavelength conversion members of Examples 1 to 3 and Comparative Example 1. Each wavelength conversion member was placed in a thermo-hygrostat (manufactured by Espec Corporation) in an atmosphere at a temperature of 60°C and a relative humidity of 90%. After 100 hours had passed, the member was removed from the thermo-hygrostat and used as a sample after the storage test.

[0166] For the samples after the storage test, the appearance was photographed from the main surface side using a digital camera (manufactured by Olympus) to obtain an evaluation image. Image analysis software was used to obtain an emission intensity profile corresponding to green, with the horizontal axis representing the distance from one side of the wavelength conversion member to the opposite side. In the obtained emission intensity profile, a relative emission intensity profile was obtained, where the arithmetic mean value of the emission intensities at three points, including the emission intensity at a midpoint equidistant from both ends of the wavelength conversion member and the emission intensities at two points 0.5 mm from the midpoint, was taken as 100%. The distance (mm) from the end corresponding to a relative emission intensity of 90% in the relative emission intensity profile was determined and used as an evaluation value for discoloration. The results are shown in Table 4.

[0167]

[0168] From Table 4, it can be seen that by forming the cut surface using a laser, fading from the edge after the high-temperature, high-humidity storage test is suppressed.

[0169] The wavelength conversion member according to the embodiment of the present disclosure is useful for various lighting light sources, in-vehicle light sources, display light sources, etc. In particular, it can be advantageously applied to backlight units of image display devices using liquid crystal.

[0170] The disclosure of Japanese Patent Application No. 2022-043592 (filing date: March 18, 2022) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A wavelength conversion member comprising a laminate comprising a wavelength conversion layer containing quantum dots and two barrier layers laminated on one main surface and the other main surface of the wavelength conversion layer, The barrier layer has a first modified portion on at least a part of its end face, The wavelength conversion layer has a second modified portion on at least a part of its end face, A wavelength conversion member in which at least a portion of the second modified portion is exposed at the end face of the laminate.

2. The wavelength conversion member according to claim 1, wherein the first modified portion and the second modified portion each have at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and a carbonyl group on their surface.

3. The wavelength conversion member according to claim 1, further comprising a cured resin which is a cured product of a photocurable composition, wherein the wavelength conversion layer is further a cured resin.

4. The wavelength conversion member according to claim 3, wherein the second modified portion includes a thermally modified product of the cured resin.

5. The wavelength conversion member according to claim 1, wherein the barrier layer comprises a thermoplastic resin.

6. The wavelength conversion member according to claim 5, wherein the first modified portion includes a thermally modified product of the thermoplastic resin.

7. The wavelength conversion member according to claim 1, wherein the quantum dot comprises at least one selected from the group consisting of perovskite quantum dots, chalcopyrite quantum dots, and indium phosphide quantum dots.

8. The wavelength conversion member according to claim 1, wherein the quantum dot includes a first quantum dot having an emission peak wavelength in the wavelength range of 475 nm to 560 nm.

9. The wavelength conversion member according to claim 1, wherein the quantum dot includes a second quantum dot having an emission peak wavelength in the wavelength range of 600 nm to 680 nm.

10. The wavelength conversion member according to any one of claims 1 to 9, wherein the laminate has an end face to which the first modified portion covers the boundary between the barrier layer and the wavelength conversion layer.

11. The wavelength conversion member according to claim 1, further comprising an end face coating layer on the end face of the laminate.

12. The wavelength conversion member according to claim 2, wherein the wavelength conversion layer has a peak intensity ratio of 1.2 or more for the hydroxyl group of the second modified portion relative to the unmodified portion in the infrared absorption spectrum.

13. The wavelength conversion member according to claim 2, wherein the wavelength conversion layer has a peak intensity ratio of 1.2 or more for the carbonyl group of the second modified portion relative to the unmodified portion in the infrared absorption spectrum.

14. A laminated sheet is prepared comprising a wavelength conversion layer containing quantum dots, and two barrier layers laminated on one main surface and the other main surface of the wavelength conversion layer, This includes obtaining a laminated body by cutting the laminated sheet into individual pieces by irradiating the main surface of the laminated sheet with laser light intersecting it, The method for manufacturing a wavelength conversion member, wherein the laser light irradiation is performed in a manner in which the laser light frequency is 5 kHz or more and 30 kHz or less, the scanning speed is 50 mm / s or more and 100 mm / s or less, and the laser light output is 3.4 W or more and 100 W or less.

15. The method for manufacturing a wavelength conversion member according to claim 14, wherein the irradiation of the laser light is performed with a number of scans per cross-section of 1 to 5.

16. The method for manufacturing a wavelength conversion member according to claim 14, wherein the irradiation of the laser light is carried out while discharging an inert gas at the laser light irradiation position.

17. The method for manufacturing a wavelength conversion member according to claim 14, wherein the laser light is a carbon dioxide laser.

18. The method for manufacturing a wavelength conversion member according to claim 14, wherein the irradiation of the laser light is carried out by providing a space on the main surface side of the laminated sheet opposite to the main surface to which the laser light is irradiated at the laser light irradiation position.

19. The method for manufacturing a wavelength conversion member according to claim 14, wherein at least a portion of the end face of the wavelength conversion layer is exposed at its cross-section.

20. The method for manufacturing a wavelength conversion member according to claim 14, wherein the laminate has a first modified portion in at least a part of the end face of the barrier layer at its cross-section.

21. The method for manufacturing a wavelength conversion member according to claim 20, wherein the first modified portion has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and a carbonyl group on its surface.

22. The method for manufacturing a wavelength conversion member according to claim 21, wherein the ratio of the density of the functional groups on the surface of the first modified portion to the density of the functional groups on the end face of the barrier layer of the laminated sheet is greater than 1.

23. The method for manufacturing a wavelength conversion member according to any one of claims 20 to 22, wherein the laminate, in its cross-section, has the first modified portion covering the boundary between the barrier layer and the wavelength conversion layer.

24. The method for manufacturing a wavelength conversion member according to claim 14, wherein the laminate has a second modified portion in at least a part of the end face of the wavelength conversion layer at its cross-section.

25. The method for manufacturing a wavelength conversion member according to claim 24, wherein the second modified portion has at least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, and a carbonyl group on its surface.

26. The method for manufacturing a wavelength conversion member according to claim 25, wherein the ratio of the density of the functional group on the surface of the second modified portion to the density of the functional group on the end face of the wavelength conversion layer of the laminated sheet is greater than 1.

27. The method for manufacturing a wavelength conversion member according to claim 14, wherein the wavelength conversion layer further comprises a cured resin which is a cured product of a photocurable composition.

28. The method for manufacturing a wavelength conversion member according to claim 14, wherein the barrier layer comprises a thermoplastic resin.

29. The method for manufacturing a wavelength conversion member according to claim 14, wherein the quantum dot comprises at least one selected from the group consisting of perovskite quantum dots, chalcopyrite quantum dots, and indium phosphide quantum dots.

30. The method for manufacturing a wavelength conversion member according to claim 14, wherein the quantum dot includes a first quantum dot having an emission peak wavelength in the wavelength range of 475 nm to 560 nm.

31. The method for manufacturing a wavelength conversion member according to claim 14, wherein the quantum dot includes a second quantum dot having an emission peak wavelength in the wavelength range of 600 nm to 680 nm.