Wavelength conversion member, light-emitting device, and liquid crystal display device

Abstract

Provided is a wavelength conversion member having a wavelength conversion layer between two substrates. Each of the two substrates includes a barrier layer and a support. The barrier layer is positioned between the support and the wavelength conversion layer. The wavelength conversion layer contains a cured product of a curable composition containing quantum dots, a polyfunctional (meth)acrylate, and a polyfunctional thiol. The ratio of the total number of thiol groups to the total number of carbon-carbon double bonds in the curable composition is 0.100 to 1.800. The reaction rate of the thiol group of the polyfunctional thiol in the cured product is 66 to 100%. The glass transition temperature Tg of the wavelength conversion layer is 3 to 120°C, and the change ΔTg in the glass transition temperature of the wavelength conversion layer before and after ultraviolet irradiation at an irradiation amount of 1600 mJ / cm2 is 10°C or less.

Description

Wavelength conversion member, light emitting device and liquid crystal display device

[0001] The present invention relates to a wavelength conversion member, a light emitting device, and a liquid crystal display device.

[0002] 2. Description of the Related Art Flat panel displays such as liquid crystal display devices are becoming more and more popular as they consume less power and require less space. A liquid crystal display device is generally composed of at least a light emitting device and a liquid crystal cell.

[0003] In recent years, quantum dots (also called quantum dots, QDs, quantum points, etc.) have been attracting attention as light-emitting materials for flat panel displays (see, for example, Patent Document 1).

[0004] WO2019 / 189496

[0005] A light-emitting device disposed in a liquid crystal display device can have at least a component containing quantum dots and a light source. Such components are generally referred to as wavelength conversion components. For example, when light from a light source is incident on the wavelength conversion component, the quantum dots are excited by the incident light and emit fluorescence. By using quantum dots with different emission characteristics, red, green, and blue emission lines can be emitted from the wavelength conversion component as fluorescence emitted by the quantum dots and / or light emitted from the light source and passed through the wavelength conversion component. This makes it possible to realize white light. Because the fluorescence emitted by quantum dots has a small half-width, the resulting white light has high brightness and excellent color reproducibility. Advances in three-wavelength light source technology using quantum dots have expanded the color reproduction range from 72% to 100% compared to the current TV standards (FHD (Full High Definition), NTSC (National Television System Committee)).

[0006] It is desirable for liquid crystal display devices to be able to display images with high brightness. However, the inventors' investigations have revealed that liquid crystal display devices having light-emitting devices with wavelength conversion materials containing quantum dots are prone to a phenomenon in which partial light-emitting defects occur (hereinafter referred to as "non-light-emitting defects").

[0007] An object of one aspect of the present invention is to provide a wavelength conversion member that can contribute to achieving both high-luminance light emission and suppression of the occurrence of non-light-emitting defects.

[0008] One aspect of the present invention is as follows: [1] A wavelength converting member having a wavelength converting layer between two substrates, each of the two substrates including a barrier layer and a support, and the barrier layer being located between the support and the wavelength converting layer, the wavelength converting layer including a cured product of a curable composition including quantum dots, a polyfunctional (meth)acrylate, and a polyfunctional thiol, the ratio of the total number of thiol groups to the total number of carbon-carbon double bonds in the curable composition (total number of thiol groups / total number of carbon-carbon double bonds, hereinafter also referred to as "total number of SH groups / total number of C=C") being 0.100 to 1.800, the reaction rate of thiol groups of the polyfunctional thiol in the cured product (hereinafter also referred to as "thiol group reaction rate") being 66% to 100%, the glass transition temperature Tg of the wavelength converting layer determined by dynamic viscoelasticity measurement being 3°C to 120°C, and 1600 mJ / cm ２ [2] A wavelength conversion member in which a change ΔTg in glass transition temperature of the wavelength conversion layer, determined by dynamic viscoelasticity measurement before and after ultraviolet irradiation at an irradiation dose of 1000 nm or less, is 10°C or less. [3] A wavelength conversion member in which a peak density (hereinafter also referred to as "ESR intensity") at g=2.000 of the wavelength conversion layer, measured by an electron spin resonance (ESR) method, is 4.0×10 ４ Spin / g or more 2.0 x 10 ６The wavelength conversion member according to [1], wherein the ΔTg is 5°C or less. [3] The wavelength conversion member according to [1] or [2], wherein the ΔTg is 5°C or less. [4] The wavelength conversion member according to any one of [1] to [3], wherein each of the two substrates further comprises an organic layer located between the barrier layer and the wavelength conversion layer. [5] The wavelength conversion member according to any one of [1] to [4], wherein each of the two substrates further comprises an organic layer between the barrier layer and the support. [6] The wavelength conversion member according to any one of [1] to [5], wherein the wavelength conversion layer has a resin layer region having a plurality of recesses, and the recesses contain the cured product. [7] The wavelength conversion member according to any one of [1] to [5], wherein the g=2.000 peak concentration of the wavelength conversion layer measured by electron spin resonance spectroscopy is 4.0×10 ４ Spin / g or more 2.0 x 10 ６

[0013] The wavelength conversion member according to [1], wherein the wavelength conversion coefficient is 1 / s / g or less, the ΔTg is 5°C or less, each of the two base materials further comprises an organic layer located between the barrier layer and the wavelength conversion layer, and an organic layer between the barrier layer and the support, the wavelength conversion layer having a resin layer region having a plurality of recesses, and the recesses contain the cured product. [8] A light emitting device comprising the wavelength conversion member according to any of [1] to [7] and a light source. [9] A liquid crystal display device comprising the light emitting device according to [8] and a liquid crystal cell.

[0009] According to one aspect of the present invention, it is possible to provide a wavelength conversion member that can contribute to achieving both high-brightness light emission and suppression of non-light-emitting defects. Also, according to another aspect of the present invention, it is possible to provide a light-emitting device including the wavelength conversion member and a liquid crystal display device including the light-emitting device.

[0010] 1 is a perspective view conceptually showing an example of a wavelength conversion member. FIG. 2 is a plan view of the wavelength conversion member of FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1 and FIG. 2. FIG. 4 is a cross-sectional view for explaining an example of the shape of a resin layer of a wavelength conversion member. FIG. 5 is a partially enlarged view of FIG. 3. FIG. 5 is a cross-sectional view conceptually showing another example of a wavelength conversion member. FIG. 6 is a cross-sectional view conceptually showing another example of a wavelength conversion member. FIG. 7 is a plan view showing an example of a pattern of a quantum dot-containing portion. FIG. 8 is a plan view showing another example of a pattern of a quantum dot-containing portion. FIG. 9 is a conceptual diagram for explaining a method of specifying the contour of a quantum dot-containing portion. FIG. 10 is a conceptual diagram for explaining an example of a method for manufacturing a wavelength conversion member. FIG. 11 is a conceptual diagram for explaining another example of a method for manufacturing a wavelength conversion member. FIG. 12 is a conceptual diagram for explaining a further example of a method for manufacturing a wavelength conversion member. FIG. 13 is a diagram conceptually showing the configuration of an example of a backlight unit. FIG. 14 is a diagram conceptually showing the configuration of an example of a liquid crystal display device.

[0011] The following description may be based on a representative embodiment of the present invention. However, the present invention is not limited to such an embodiment. In this invention and this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0012] In the present invention and this specification, the "half width" of a peak refers to the width of the peak at half the peak height. Furthermore, light having a central emission wavelength in a wavelength band ranging from 400 nm to less than 500 nm is called blue light, light having a central emission wavelength in a wavelength band ranging from 500 nm to less than 600 nm is called green light, and light having a central emission wavelength in a wavelength band ranging from 600 nm to 680 nm is called red light.

[0013] In the present invention and this specification, the term "(meth)acrylate" refers to a compound containing one or more (meth)acryloyl groups in one molecule, and the term "(meth)acryloyl group" is used to refer to either or both of an acryloyl group and a methacryloyl group. The functionality of a "(meth)acrylate" refers to the number of (meth)acryloyl groups contained in one molecule of the (meth)acrylate. With respect to a (meth)acrylate, "monofunctional" refers to one (meth)acryloyl group contained in one molecule, and "polyfunctional" refers to two or more (meth)acryloyl groups contained in one molecule. In addition, a (meth)acryloyl group may be contained in the (meth)acrylate in the form of a (meth)acryloyloxy group. The term "(meth)acryloyloxy group" is used to refer to either or both of an acryloyloxy group and a methacryloyloxy group.

[0014] In the present invention and this specification, with regard to (meth)acrylates, (meth)acrylates that may correspond to either the first (meth)acrylate or the second (meth)acrylate described below shall be interpreted as the second (meth)acrylate.

[0015] In the present invention and this specification, a "curable composition" is a composition containing at least one polymerizable compound, and has the property of being cured by being subjected to a polymerization treatment such as light irradiation or heating. Also, a "polymerizable compound" is a compound containing one or more polymerizable functional groups in one molecule. A "polymerizable functional group" is a group that can participate in a polymerization reaction, and a "(meth)acryloyl group" is a polymerizable functional group.

[0016] In the present invention and this specification, a "multifunctional thiol" is a compound having two or more thiol groups in one molecule. The functionality of a thiol refers to the number of thiol groups contained in one thiol molecule.

[0017] [Wavelength Conversion Member] One aspect of the present invention relates to a wavelength conversion member having a wavelength conversion layer between two substrates. Each of the two substrates includes a barrier layer and a support, and the barrier layer is located between the support and the wavelength conversion layer. The wavelength conversion layer includes a cured product of a curable composition containing quantum dots, a polyfunctional (meth)acrylate, and a polyfunctional thiol. The ratio of the total number of thiol groups to the total number of carbon-carbon double bonds in the curable composition (total number of thiol groups / total number of carbon-carbon double bonds) is 0.100 or more and 1.800 or less. The reaction rate of the thiol groups of the polyfunctional thiol in the cured product is 66% or more and 100% or less. The glass transition temperature Tg of the wavelength conversion layer determined by dynamic viscoelasticity measurement is 3°C or more and 120°C or less, and 1600 mJ / cm ２ The change ΔTg in glass transition temperature of the wavelength conversion layer determined by measuring dynamic viscoelasticity before and after ultraviolet irradiation at an irradiation dose of 1000 nm is 10° C. or less.

[0018] After extensive research, the present inventors have newly discovered that a liquid crystal display device having a light-emitting device equipped with the wavelength conversion member can emit light with high brightness and can suppress the occurrence of non-luminescent defects. The present inventors speculate that the reason for this is as follows: Coordinating ligands to the surface of quantum dots is said to contribute to improved brightness. In this regard, it is believed that a compound having a thiol group can function as a ligand for the quantum dots by adsorbing the thiol group to the surface of the quantum dots. Furthermore, it is believed that by including a polyfunctional thiol in a curable compound together with a (meth)acrylate, some of the thiol groups contained in the polyfunctional thiol can undergo a crosslinking reaction with the (meth)acryloyl group of the (meth)acrylate, which may contribute to suppressing brightness reduction. Furthermore, the present inventors speculate that the occurrence of non-luminescent defects can be suppressed by having the above-mentioned total number of SH groups / total number of C=C groups, thiol group reactivity, Tg, and ΔTg within the above ranges. The inventors believe that the above-mentioned ranges of the total number of SH groups / total number of C=C groups, the thiol group reactivity, Tg, and ΔTg contribute to preventing the quantum dots from being deactivated by oxygen entering the wavelength conversion layer, thereby suppressing the occurrence of non-luminescent defects. Furthermore, the wavelength conversion member has a wavelength conversion layer between two substrates, and a barrier layer is positioned between the wavelength conversion layer and the support of the substrate, which can contribute to protecting the quantum dots contained in the wavelength conversion layer from oxygen and the like. Hereinafter, "substrate" will also be referred to as "substrate film." However, the present invention is not limited to the above and other conjectures of the inventors.

[0019] <Total Number of SH Groups / Total Number of C=C Groups> The ratio of the total number of thiol groups to the total number of carbon-carbon double bonds in the curable composition (total number of thiol groups / total number of carbon-carbon double bonds (total number of SH groups / total number of C=C groups)) is 0.100 or more and 1.800 or less, from the viewpoint of suppressing the occurrence of non-luminescent defects. From the viewpoint of achieving both higher luminescence brightness and suppressing the occurrence of non-luminescent defects, the total number of SH groups / total number of C=C groups is preferably 0.200 or more, and more preferably 0.300 or more. The total number of SH groups / total number of C=C groups can be, for example, 1.600 or less, 1.400 or less, 1.200 or less, 1.000 or less, 0.900 or less, or 0.850 or less.

[0020] The total number of SH groups / total number of C=C of the curable composition can be determined by a known method. For example, the total number of SH groups / total number of C=C can be calculated from the charging ratio of the thiol group (SH group)-containing compound and the carbon-carbon double bond (C=C)-containing compound of the curable composition. When calculating the total number of SH groups / total number of C=C, if the curable composition contains a monofunctional thiol in addition to a polyfunctional thiol, the number of thiol groups possessed by the monofunctional thiol is also included in the total number of SH groups. When calculating the total number of SH groups / total number of C=C, if the curable composition contains another carbon-carbon double bond-containing compound in addition to a polyfunctional (meth)acrylate, the number of carbon-carbon double bonds possessed by such carbon-carbon double bond-containing compound is also included in the total number of carbon-carbon double bonds.

[0021] <Thiol Group Reaction Rate> The reaction rate of the thiol groups of the polyfunctional thiol in the cured product (thiol group reaction rate) is 66% or more and 100% or less from the viewpoint of suppressing the occurrence of non-luminescent defects. From the viewpoint of further suppressing the occurrence of non-luminescent defects, the thiol group reaction rate is preferably 70% or more, more preferably 75% or more, even more preferably 80% or more, even more preferably 85% or more, even more preferably 90% or more, and even more preferably 95% or more. When all the thiol groups of the polyfunctional thiol contained in the cured product have reacted, the thiol group reaction rate is 100%. From the viewpoint of suppressing the occurrence of non-luminescent defects, the thiol group reaction rate may be 100%. The thiol group reaction rate can be controlled, for example, by the amount of polymerization initiator used, curing conditions (e.g., the amount of light irradiation for photocuring), etc.

[0022] The thiol group reaction rate of the cured product can be determined by a known method. A specific example of a method for determining the thiol group reaction rate of the cured product by FT-IR (Fourier Transform Infrared Spectroscopy) will be described later in the Examples section.

[0023] <Glass transition temperature Tg of wavelength conversion layer> The glass transition temperature Tg of the wavelength conversion layer is 3°C or higher and 120°C or lower from the viewpoint of suppressing the occurrence of non-luminescent defects. From the viewpoint of further suppressing the occurrence of non-luminescent defects, the Tg is preferably 5°C or higher, and more preferably 10°C or higher. Furthermore, from the viewpoint of further suppressing the occurrence of non-luminescent defects, the Tg is preferably 115°C or lower, and more preferably 110°C or lower. The glass transition temperature Tg of the wavelength conversion layer can be controlled by the formulation of the curable composition for forming the cured product contained in the wavelength conversion layer, the curing conditions (e.g., the amount of light irradiation for photocuring), etc.

[0024] In the present invention and this specification, the glass transition temperature Tg of the wavelength conversion layer is determined by dynamic viscoelasticity measurement using a measurement sample cut out from the wavelength conversion layer taken out of the wavelength conversion member to be measured. The measurement conditions are a grip distance of 20 mm, a temperature rise rate of 5°C / min, a measurement temperature range of -20°C to 200°C, and a frequency of 1 Hz. Specific examples of methods for measuring the glass transition temperature Tg include the measurement method described in the Examples section below.

[0025] <ΔTg of wavelength converting layer> In the wavelength converting member, ΔTg of 1600 mJ / cm ２ The change in glass transition temperature ΔTg of the wavelength conversion layer determined by dynamic viscoelasticity measurement before and after ultraviolet irradiation at an irradiation dose of 10°C or less is 10°C or less. A ΔTg of 10°C or less can also contribute to suppressing the occurrence of non-luminescent defects. From the viewpoint of further suppressing the occurrence of non-luminescent defects, ΔTg is preferably 9°C or less, more preferably 8°C or less, even more preferably 7°C or less, even more preferably 6°C or less, and even more preferably 5°C or less. ΔTg can be 0°C or more, and can also be 0°C. From the viewpoint of suppressing the occurrence of non-luminescent defects, the smaller the ΔTg value, the more preferable. ΔTg can be controlled by the formulation of the curable composition for forming the cured product contained in the wavelength conversion layer, the curing conditions (e.g., the light irradiation dose for photocuring), etc. The glass transition temperature Tg after ultraviolet irradiation may be higher or lower than the glass transition temperature Tg before ultraviolet irradiation. ΔTg is calculated as the absolute value of the difference between the glass transition temperatures Tg before and after ultraviolet irradiation.

[0026] The above 1600 mJ / cm ２ The ultraviolet irradiation at the irradiation dose of is performed on a randomly selected surface of the wavelength conversion member. The method for measuring the glass transition temperature Tg is as described above.

[0027] <ESR Strength> The ESR strength of the wavelength conversion layer is set to 4.0×10 from the viewpoint of further suppressing the occurrence of non-radiative defects. ４ Spin / g or more 2.0 x 10 ６It is preferable that the spins / g or less. The present inventors believe that a part of the thiol groups of a thiol group (SH group)-containing compound such as a polyfunctional thiol may exist as a thiyl radical (S·) in the wavelength conversion layer. The present inventors also speculate that the inclusion of a predetermined amount of thiyl radical (S·) in the wavelength conversion layer may contribute to further suppressing the occurrence of non-radiative defects. In this regard, the present inventors believe that the ESR intensity can be an indicator of the amount of thiyl radical (S·). From the viewpoint of further suppressing the occurrence of non-radiative defects, the ESR intensity of the wavelength conversion layer should be 4.2×10 ４ spins / g or more, and 4.5×10 ４ The ESR intensity of the wavelength conversion layer is preferably 1.0×10 ５ The ESR intensity of the wavelength conversion layer can be controlled by the formulation of the curable composition for forming the cured product contained in the wavelength conversion layer, the curing conditions (e.g., the amount of light irradiation for photocuring), etc.

[0028] In the present invention and this specification, the g = 2,000 peak concentration (ESR intensity) of the wavelength conversion layer measured by electron spin resonance (ESR) is determined by the following method. Ten measurement samples (size: 5 mm x 35 mm) cut from the wavelength conversion layer removed from the wavelength conversion member to be measured are placed in a measurement container, and measurements are performed using an X-band ESR measurement device under the following measurement conditions: microwave: 1.0 mW, magnetic modulation amplitude: 5.0 gauss, measurement temperature: room temperature (25 ° C). The absolute value of the difference between the maximum and minimum values ​​of the peak between 3400 and 3430 gauss (corresponding to a g value of 2,000) is normalized (i.e., divided) by the mass of the sample placed in the measurement container to calculate the spin concentration [spins / g]. Specific examples of measurement devices include the measurement devices described in the Examples section below.

[0029] The wavelength conversion member will be described in more detail below.

[0030] <Curable Composition> (Polyfunctional Thiol) The polyfunctional thiol contained in the curable composition is a difunctional or higher thiol, preferably a trifunctional or higher thiol. The polyfunctional thiol can be, for example, an octafunctional or lower, heptafunctional or lower, hexafunctional or lower, pentafunctional or lower, or tetrafunctional or lower thiol. From the viewpoint of improving the durability of a wavelength conversion member containing a cured product obtained by curing the curable composition, the polyfunctional thiol is preferably one or more types selected from the group consisting of difunctional to hexafunctional polyfunctional thiols, more preferably one or more types selected from the group consisting of difunctional to tetrafunctional polyfunctional thiols, even more preferably one or more types selected from the group consisting of trifunctional or tetrafunctional polyfunctional thiols, and even more preferably a trifunctional thiol. In terms of durability, a wavelength conversion member that exhibits little decrease in brightness even after long-term use can be said to be a wavelength conversion member with excellent durability.

[0031] Specific examples of polyfunctional thiols include ethylene bis(thioglycolate), diethylene glycol bis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), 1,2-propylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptobutyrate), 1,4-butanediol bis(3-mercaptopropionate), 1,4-butanediol bis(3-mercaptobutyrate), 1,4- ... (styryloxy)butane, 1,8-octanediol bis(3-mercaptopropionate), 1,8-octanediol bis(3-mercaptobutyrate), hexanediol bisthioglycolate, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), Glycolate, trimethylolpropane tris(3-mercaptopropionate), tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolethane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptoisobutyrate), pentaerythritol tetrakis(2-mercaptoisobutylate) Examples of the polyfunctional thiol include pentaerythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(2-mercaptopropionate), dipentaerythritol hexakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptoisobutyrate), dipentaerythritol hexakis(2-mercaptoisobutyrate), pentaerythritol tetrakisthioglycolate, dipentaerythritol hexakisthioglycolate, and dipentaerythritol hexakis(3-mercaptopropionate). Commercially available products can be used as the polyfunctional thiol, and those synthesized by known methods can also be used.

[0032] The molecular weight of the polyfunctional thiol contained in the curable composition can be, for example, 200 or more, and from the viewpoint of improving durability, it is preferably 300 or more. From the viewpoint of further improving brightness, the molecular weight of the polyfunctional thiol is preferably 1000 or less, and more preferably 500 or less.

[0033] In the present invention and this specification, the term "molecular weight" refers to the weight average molecular weight for polymers (polymers also include oligomers). The weight average molecular weight refers to the weight average molecular weight obtained by converting a measured value measured by gel permeation chromatography (GPC) into polystyrene equivalents. The following conditions can be used as the GPC measurement conditions, for example. GPC apparatus: HLC-8120 (manufactured by Tosoh Corporation) Column: TSK gelMultipore HXL-M (manufactured by Tosoh Corporation, 7.8 mm ID (Inner Diameter) x 30.0 cm)

[0034] In the curable composition, the content of the multifunctional thiol is preferably 5.0% by mass or more, more preferably 10.0% by mass or more, and even more preferably 15.0% by mass or more, relative to the total amount of the composition, from the viewpoint of improving the durability and brightness of the wavelength conversion member containing the cured product obtained by curing the curable composition. Furthermore, from the viewpoint of further improving the durability and brightness, the content of the multifunctional thiol is preferably 40.0% by mass or less, more preferably 35.0% by mass or less, even more preferably 30.0% by mass or less, even more preferably 25.0% by mass or less, and even more preferably 20.0% by mass or less, relative to the total amount of the composition. The curable composition may contain only one type of multifunctional thiol, or may contain two or more types. When two or more types of multifunctional thiols are contained, the content refers to the total content of the two or more types of multifunctional thiols. This also applies to the various components of the present invention and this specification. In the present invention and this specification, the content of each component relative to the total amount of the composition refers to a content calculated assuming that the total content of all components excluding the solvent is 100.0 mass% when the curable composition contains a solvent. In the present invention and this specification, the content of each component relative to the total amount of the composition refers to a content calculated assuming that the total content of all components contained in the composition is 100.0 mass% when the curable composition does not contain a solvent.

[0035] (Polyfunctional (meth)acrylate (first (meth)acrylate)) In this specification, the polyfunctional (meth)acrylate is also referred to as the “first (meth)acrylate.” The polyfunctional (meth)acrylate is one or more types of difunctional or higher (meth)acrylates, and may be one or more types selected from the group consisting of difunctional to octafunctional, difunctional to heptafunctional, difunctional to hexafunctional, difunctional to pentafunctional, or difunctional to tetrafunctional polyfunctional (meth)acrylates.

[0036] Specific examples of bifunctional (meth)acrylates include neopentyl glycol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl di(meth)acrylate, and tricyclodecane dimethanol di(meth)acrylate.

[0037] Specific examples of trifunctional or higher (meth)acrylates include ECH (epichlorohydrin)-modified glycerol tri(meth)acrylate, EO (ethylene oxide)-modified glycerol tri(meth)acrylate, PO (propylene oxide)-modified glycerol tri(meth)acrylate, Oxide-modified glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate, PO-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and dipentaerythritol poly(meth)acrylate.

[0038] The molecular weight of the polyfunctional (meth)acrylate contained in the curable composition as the first (meth)acrylate may be, for example, not less than 200. From the viewpoint of the viscosity of the curable composition, the molecular weight of the polyfunctional (meth)acrylate is preferably not more than 1000, and more preferably not more than 500.

[0039] In the curable composition, the content of the polyfunctional (meth)acrylate is preferably 10.0 mass% or more, more preferably 20.0 mass% or more, and even more preferably 30.0 mass% or more, based on the total amount of the composition, from the viewpoint of improving durability. The curable composition may contain only one type of polyfunctional (meth)acrylate, or may contain two or more types.

[0040] (Second (meth)acrylate) The curable composition may contain a monofunctional or higher functional (meth)acrylate having a functional group selected from the group consisting of a carboxy group, a hydroxy group, a phosphate group, and an amino group. In this specification, such a (meth)acrylate is also referred to as a "second (meth)acrylate." It is presumed that the inclusion of the second (meth)acrylate in the curable composition may contribute to improving the brightness of a wavelength conversion member containing a cured product obtained by curing this curable composition.

[0041] The second (meth)acrylate has one or more functional groups selected from the group consisting of a carboxy group, a hydroxy group, a phosphate group, and an amino group in one molecule. The number of such functional groups in one molecule can be 1 to 3, preferably 1 or 2, and more preferably 1. When the second (meth)acrylate has two or more of the above functional groups in one molecule, these two or more functional groups may be the same or different. The carboxy group may be contained in the form of -COOH or in the form of a salt. A salt of a carboxy group may be -COO － M ＋ The phosphate group is a salt represented by -P=O(OH) ２ is a monovalent functional group represented by -P=O(OH) ２ The salt of a phosphate group may be in the form of -P=O(O － M ＋ ) ２ In the above, M ＋represents a cation such as an alkali metal ion. The amino group may be a primary amino group, a secondary amino group, or a tertiary amino group. From the viewpoint of further improving brightness, the functional group is preferably a carboxy group, a hydroxy group, or a phosphate group, and more preferably a carboxy group.

[0042] The second (meth)acrylate is a monofunctional or higher functional (meth)acrylate. From the viewpoint of further improving brightness, the second (meth)acrylate is preferably a monofunctional, bifunctional, or trifunctional (meth)acrylate, more preferably a monofunctional or bifunctional (meth)acrylate, and even more preferably a monofunctional (meth)acrylate. The monofunctional (meth)acrylate can be represented, for example, by the formula: A-L-X. In the formula, A represents any of the functional groups described above, L represents a divalent linking group, and X represents a (meth)acryloyl group or a (meth)acryloyloxy group. The divalent linking group represented by L can be, for example, one or a combination of two or more divalent groups selected from the group consisting of an alkylene group, a cycloalkylene group, and an ester group (—O—C(═O)—). Examples of alkylene groups include alkylene groups having a linear or branched structure and having 1 to 3 carbon atoms (e.g., methylene, ethylene, propylene, etc.). Examples of cycloalkylene groups include cycloalkylene groups having 5 to 8 carbon atoms (e.g., cyclopentylene, cyclohexylene, cycloheptylene, cyclooctylene, etc.). The alkylene group may or may not have a substituent, and is preferably an unsubstituted alkylene group. This also applies to cycloalkylene groups. An example of a monofunctional (meth)acrylate having a carboxy group is acrylic acid. Acrylic acid is a carboxyl group formed by the reaction of CH ２ It is a carboxylic acid represented by =CHCOOH, and the carbonyl group (-C(=O)-) is both a part of the carboxy group and a part of the acryloyl group.

[0043] The molecular weight of the (meth)acrylate contained as the second (meth)acrylate is preferably equal to or less than the molecular weight of the polyfunctional thiol contained in the curable composition, and more preferably less than the molecular weight of the polyfunctional thiol. When the molecular weight of the (meth)acrylate contained as the second (meth)acrylate is equal to or less than the molecular weight of the polyfunctional thiol contained in the curable composition, the molecular weight ratio calculated as "molecular weight ratio (unit: %) = (molecular weight of the second (meth)acrylate / molecular weight of the polyfunctional thiol) × 100" is 100% or less, preferably 80% or less, and more preferably 50% or less.

[0044] The molecular weight of the (meth)acrylate contained as the second (meth)acrylate in the curable composition can be, for example, 50 or more, and from the viewpoint of improving durability, it is preferably 70 or more, and more preferably 100 or more. Furthermore, from the viewpoint of further improving brightness, the molecular weight of the (meth)acrylate contained as the second (meth)acrylate in the curable composition is preferably 500 or less, more preferably 400 or less, even more preferably 300 or less, and even more preferably 200 or less.

[0045] Specific examples of the second (meth)acrylate include carboxy group-containing (meth)acrylates such as acrylic acid, β-carboxyethyl acrylate, 2-acryloyloxyethyl succinic acid, and 2-acryloyloxyethyl hexahydrophthalic acid; phosphate group-containing (meth)acrylates such as 2-acryloyloxyethyl acid phosphate; and hydroxy group-containing (meth)acrylates such as 2-hydroxyethyl acrylate.

[0046] In the curable composition, the content of the second (meth)acrylate is preferably 0.5% by mass or more, and more preferably 3.0% by mass or more, relative to the total amount of the composition, from the viewpoint of further improving brightness. Furthermore, the content of the second (meth)acrylate is preferably 20.0% by mass or less, relative to the total amount of the composition, from the viewpoint of further improving durability. The curable composition may contain only one type of (meth)acrylate as the second (meth)acrylate, or may contain two or more types.

[0047] (Quantum Dots) The curable composition contains one or more quantum dots that can emit fluorescence when excited by excitation light.

[0048] The curable composition may contain only one type of quantum dot, or may contain two or more types of quantum dots with different light-emitting properties. Known quantum dots include quantum dots (A) having a central emission wavelength in the wavelength range of 600 nm to 680 nm, quantum dots (B) having a central emission wavelength in the wavelength range of 500 nm to less than 600 nm, and quantum dots (C) having a central emission wavelength in the wavelength range of 400 nm to less than 500 nm. The quantum dots (A) can be excited by excitation light to emit red light, the quantum dots (B) can emit green light, and the quantum dots (C) can emit blue light. For example, when blue light is incident as excitation light on a wavelength conversion member containing quantum dots (A) and quantum dots (B), white light can be realized by the red light emitted by the quantum dots (A), the green light emitted by the quantum dots (B), and the blue light that has passed through the wavelength conversion member. Furthermore, by irradiating ultraviolet light as excitation light onto a wavelength conversion member containing quantum dots (A), (B), and (C), white light can be realized by the red light emitted by the quantum dot (A), the green light emitted by the quantum dot (B), and the blue light emitted by the quantum dot (C).

[0049] Examples of quantum dots include core-shell semiconductor nanoparticles. Generally, semiconductor particles with a particle size of 100 nm or less (e.g., several nm to several tens of nm) can be called semiconductor nanoparticles. Cores include II-VI semiconductor nanoparticles, III-V semiconductor nanoparticles, and multi-component semiconductor nanoparticles. Specific examples include, but are not limited to, CdSe, CdTe, CdS, ZnS, ZnSe, ZnTe, InP, InAs, and InGaP. CdSe, CdTe, InP, and InGaP are preferred because they can emit visible light with high efficiency. Shells can include, but are not limited to, CdS, ZnS, ZnO, GaAs, and / or composites thereof. For quantum dots, reference can be made to known techniques such as paragraphs 0060 to 0066 of JP 2012-169271 A and paragraphs 0070 to 0076 of WO 2018 / 186300. Commercially available quantum dots can be used, and those produced by known methods can also be used. The luminescence properties of quantum dots can usually be adjusted by the composition and / or size of the particles.

[0050] In the curable composition, the content of the quantum dots can be, for example, in the range of 0.1 to 10.0 mass % relative to the total amount of the composition.

[0051] (Optional Component) Monofunctional (Meth)acrylate The curable composition may optionally contain one or more monofunctional (meth)acrylates in addition to the above components, for example, as a diluent. Such monofunctional (meth)acrylates do not include monofunctional (meth)acrylates having the functional group described above that the second (meth)acrylate has. Examples of monofunctional (meth)acrylates that may be optionally contained include isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, lauryl (meth)acrylate, etc.

[0052] The content of the monofunctional (meth)acrylate may be 0% by mass, or may be 0% by mass or more, relative to the total amount of the curable composition. When the curable composition contains the monofunctional (meth)acrylate, the content thereof is preferably 50.0% by mass or less, relative to the total amount of the curable composition, from the viewpoint of further improving durability.

[0053] Additives The curable composition may optionally contain one or more additives in addition to the above components. Specific examples of additives include polymerization initiators, polymers, viscosity modifiers, silane coupling agents, surfactants, antioxidants, oxygen getter agents, polymerization inhibitors, inorganic particles, and light-scattering particles. For details on specific additives, see, for example, paragraphs 0108 to 0169 of WO 2018 / 186300. The curable composition may be solvent-free or may contain one or more solvents as needed. The type and amount of solvent are not limited. For example, one or more organic solvents may be used as the solvent.

[0054] In one embodiment, the curable composition may contain a phenolic compound. The phenolic compound may contribute to suppressing viscosity changes over time in the curable composition, i.e., improving liquid stability. This point is further explained below. Compositions containing both a thiol group-containing compound and a (meth)acryloyl group-containing compound tend to experience a viscosity increase over time due to the progression of the thiol-ene reaction. In contrast, by adding a phenolic compound to such a composition, the phenolic compound can act as a polymerization inhibitor, thereby suppressing the viscosity increase. The present inventors also believe that the phenolic compound may contribute to further improving the brightness of a wavelength conversion member containing a cured product obtained by curing the curable composition. Although this is merely speculation, the present inventors believe that the phenolic compound may be adsorbed on the surface of quantum dots, which may contribute to further improving brightness. However, this is merely speculation and does not limit the present invention.

[0055] In the present invention and this specification, the term "phenolic compound" is used to encompass phenol and its derivatives. The phenolic compound can be represented by the following formula 1.

[0056]

[0057] In formula 1, R １ ~R ５ each independently represents a hydrogen atom or a substituent. Examples of the substituent include a hydroxy group, an alkyl group, and a carboxy group optionally substituted with an alkyl group. Examples of the alkyl group include an alkyl group having a linear or branched structure and 1 to 6 carbon atoms. The alkyl group includes both unsubstituted and substituted alkyl groups. When substituted, the carbon number refers to the number of carbon atoms excluding the substituent. Examples of the substituent that can substitute an alkyl group include a hydroxy group and a carboxy group. In one embodiment, the alkyl group is preferably an unsubstituted alkyl group. The above also applies to an alkyl group contained in an alkoxy group and an alkyl group that can substitute a carboxy group.

[0058] The number of hydroxy groups contained in one molecule of the phenolic compound is preferably in the range of 1 to 3, more preferably 2 or 3, and even more preferably 3. In phenolic compounds having multiple hydroxy groups, the substitution positions of the hydroxy groups are not limited, and the hydroxy groups can be substituted at any positions.

[0059] Specific examples of phenolic compounds include pyrogallol, methyl gallate, 4-tert-butylpyrocatechol, 2,6-di-tert-butyl-p-cresol, 4-methoxy-phenol, 2-tert-butyl-4,6-dimethylphenol, 4,4'-butylidenebis(6-tert-butyl-m-cresol), 2,6-di-tert-butylphenol, 2,2',6,6'-tetra-tert-butyl-[1,1'-biphenyl]-4,4'-diol, and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid.

[0060] A preferred phenolic compound is pyrogallol.

[0061] In the curable composition, the content of the phenolic compound is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, and even more preferably 0.005% by mass or more, relative to the total amount of the composition, from the viewpoint of further improving brightness and / or further improving liquid stability. From the viewpoint of further suppressing brightness reduction, i.e., further improving durability, the content of the phenolic compound in the curable composition is preferably 0.500% by mass or less, more preferably 0.300% by mass or less, and even more preferably 0.100% by mass or less, relative to the total amount of the composition. In the curable composition, the content of pyrogallol is preferably within the above range.

[0062] The curable composition can be prepared by mixing the various components described above simultaneously or sequentially in any order.

[0063] <Wavelength Conversion Layer> The wavelength conversion layer of the wavelength conversion member includes a cured product obtained by curing the curable composition. The cured product may be a cured product in which the polymerization reaction of the curable composition has partially progressed (generally referred to as a partially cured product, a semi-cured product, etc.), or a cured product in which the polymerization reaction has saturated or nearly saturated (generally referred to as a fully cured product, etc.).

[0064] In one embodiment, the wavelength conversion layer may have the cured product (hereinafter also referred to as "quantum dot-containing portion") and a resin layer region having a plurality of recesses, and the cured product may be contained in at least the recesses. Specifically, the resin layer may have a plurality of recesses that are discretely arranged. Specific embodiments of such a wavelength conversion layer will be described below with reference to the drawings. However, the embodiments shown in the drawings are merely examples, and the present invention is not limited to the exemplified embodiments.

[0065] Fig. 1 shows a perspective view of an example of a wavelength conversion member, Fig. 2 shows a plan view of the wavelength conversion member shown in Fig. 1, and Fig. 3 shows cross-sectional views taken along line III-III in Fig. 1 and Fig. 2. The plan view of the wavelength conversion member is a view of the wavelength conversion member from a direction perpendicular to the main surface (largest surface), and in this specification, unless otherwise noted, the plan view is a view of the wavelength conversion member from the second base film side.

[0066] 1 to 3, the wavelength conversion member 10 has a first base film 12, a second base film 14, and a wavelength converting layer 16. To clearly show the configuration of the wavelength conversion member 10, the second base film 14 is shown by a dashed line in Fig. 1, and is omitted in Fig. 2.

[0067] 3, the first base film 12 includes, for example, a support 12a and a barrier film 12b. Similarly, the second base film 14 includes a support 14a and a barrier film 14b.

[0068] 3 , the wavelength conversion layer 16 includes a resin layer 18 (see FIG. 4 ) having recesses 18 a formed discretely in the surface direction (main surface direction) of the wavelength conversion member 10, and a cured product (quantum dot-containing portion) 20 formed by curing the curable composition in the recesses 18 a of the resin layer 18. The quantum dot-containing portion 20 includes quantum dots 24 and a matrix 26 formed by a polymerization reaction of a polymerizable compound. That is, the wavelength conversion layer 16 includes a plurality of quantum dot-containing portions 20 each containing quantum dots 24, spaced apart in the surface direction. More specifically, the quantum dot-containing portions, which are regions containing quantum dots 24, are spaced apart in the surface direction by walls that form the recesses 18 a of the resin layer 18 and are discretely arranged in the surface direction.

[0069] In the present invention and this specification, the term "discretely arranged" more specifically means that, when observed (planar view) from a direction perpendicular to the main surface of the first substrate film 12, as shown in Figures 1 and 2, multiple quantum dot-containing portions 20 are arranged in isolation without contact with each other in the plane direction of the first substrate film 12. In other words, the plane direction of the film is a two-dimensional direction along the film surface (the main surface of the film). In the example shown in Figure 1, the quantum dot-containing portions are cylindrical and are surrounded by a resin layer 18 in the plane direction of the first substrate film 12. The resin layer 18 makes it difficult for oxygen to penetrate into each quantum dot-containing portion from the plane direction of the first substrate film 12.

[0070] Preferably, at least the wall portion of the resin layer 18 that forms the recess 18a, and more preferably the entire region of the resin layer 18, is impermeable to oxygen. This allows the wavelength conversion layer 16 to prevent deterioration of the quantum dots 24 in the quantum dot-containing portion 20. In the present invention and this specification, "impermeable to oxygen" means that the oxygen transmission rate is 10 cc / (m ２ The oxygen permeability of the resin layer 18, which is impermeable to oxygen, is 1 cc / (m ２ ·day·atm) or less, and more preferably 1×10 －１ cc / (m ２ The SI unit of oxygen permeability is [fm / (s Pa)]. "fm" stands for femtometer. 1 fm = 1 x 10 －１５ The unit is "cc / (m ２ · day · atm) is converted into the formula "1 fm / (s·Pa) = 8.752 cc / (m ２The oxygen permeability can be converted to SI units using the unit "oxygen permeability" (unit: 1 / 2 day atm) in the present invention. In addition, in the present invention, the oxygen permeability is a value measured using an oxygen gas permeability measuring device (OX-TRAN 2 / 20 manufactured by MOCON) under conditions of a measurement temperature of 23°C and a relative humidity of 90%. In addition, in the present invention and this specification, "impermeable" and "barrier property" have the same meaning. For example, in the present invention and this specification, "gas barrier property" means impermeable to gas (gas), and "water vapor barrier property" means impermeable to water vapor.

[0071] In the wavelength conversion layer 16, the quantum dot-containing portions 20 are arranged discretely in two dimensions. Therefore, assuming that the wavelength conversion member 10 is a portion of a long film, as shown by the dashed-dotted line in FIG. 2 , no matter where the wavelength conversion member 10 is linearly cut, the quantum dot-containing portions other than the cut portion are surrounded by the resin layer 18 and remain sealed in the planar direction. Furthermore, the quantum dot-containing portions cut and exposed to the outside air may lose their function as regions containing the original quantum dots 24. However, the quantum dot-containing portions at the cut positions, i.e., the quantum dot-containing portions at the end portions in the planar direction, are usually covered by components such as a frame constituting a display device (or the like), and therefore are not required to function as regions containing quantum dots, and therefore do not affect the performance of the wavelength conversion member. Furthermore, the deactivated quantum dots can become a resin layer that protects the quantum dot-containing portions not exposed to the outside air from the outside air.

[0072] In the wavelength conversion member 10, the first base film 12 is laminated on the main surface of the resin layer 18 of the wavelength conversion layer 16 on the bottom side of the recess 18a. That is, the first base film 12 is laminated on the main surface of the resin layer 18 on the closed surface (closed end) side of the recess 18a. In the example shown, the first base film 12 is laminated with the barrier film 12b facing the resin layer 18. On the other hand, the second base film 14 is laminated on the main surface of the resin layer 18 constituting the wavelength conversion layer 16 on the side opposite to the first base film 12. That is, the second base film 14 is laminated on the main surface of the resin layer 18 on the open surface (open end) side of the recess 18a. In the example shown, the second base film 14 is laminated with the barrier film 14b facing the resin layer 18.

[0073] Depending on the method for forming the resin layer, the wavelength conversion layer may have through holes instead of recesses, with the base film as the bottom and the quantum dot-containing portions filled in the through holes. In this case, one of the two base films sandwiching the resin layer, i.e., the wavelength conversion layer, may be regarded as a first base film and the other as a second base film, and the through holes may be regarded as recesses in the resin layer, the first base film as the bottom of the recesses in the resin layer, and the end of the wall of the resin layer 18 on the side of the base film regarded as the second base film may be separated from the second base film, as described below.

[0074] 3 , in wavelength conversion member 10, the wall portion forming recess 18a of resin layer 18 preferably has an end portion on the second base film 14 side separated from second base film 14. Furthermore, in wavelength conversion member 10, quantum dot-containing portions are preferably present between second base film 14 and the end portion on the second base film 14 side of the wall portion of resin layer 18 separated from second base film 14. In a wavelength conversion member having a configuration in which a wavelength conversion layer in which the quantum dot-containing portion is divided into multiple regions is sealed with two base films, gaps are provided between the wall portions dividing the quantum dot-containing portion into multiple regions and the base films, and quantum dots are present in these gaps as well, thereby increasing the adhesion between the wavelength conversion layer and the base films.

[0075] In the following description, the second substrate film 14 side of the wavelength conversion member 10, i.e., the opening side of the recess 18a of the resin layer 18, will be referred to as "top", and the first substrate film 12 side, i.e., the bottom side of the recess 18a of the resin layer 18, will be referred to as "bottom".

[0076] The wall portions forming the recesses 18a of the resin layer 18 specifically refer to the portions between the recesses 18a of the resin layer 18 in the surface direction of the base film and the portions forming the outer periphery in the surface direction of the resin layer 18. In other words, the wall portions forming the recesses 18a of the resin layer 18 refer to the resin layer 18 in the regions between the quantum dot-containing portions in the surface direction of the wavelength conversion layer 16 and in the regions outside the outermost quantum dot-containing portions in the surface direction.

[0077] In the example shown in FIGS. 1 to 3 , the quantum dot-containing portion in the recess 18 a is cylindrical, and the wall portion forming the recess 18 a in the resin layer 18 has a rectangular cross-sectional shape. However, the present invention is not limited to this, and the cross-sectional shape of the wall portion can be various shapes. For example, the wall portion forming the recess 18 a in the resin layer 18 may have a trapezoidal cross-sectional shape as conceptually shown on the left side of FIG. 4 , or may have a cross-sectional shape in which the corners on the upper base of the trapezoid are chamfered into a curved surface as conceptually shown on the right side of the same. As shown in FIG. 4 , the cross-sectional shape of the wall portion of the resin layer 18 is preferably a shape that gradually widens from the upper end downward at least partially, preferably from the upper end to the lower end. Here, "from the upper end downward" means from the end on the second substrate film 14 side toward the first substrate film 12 side. In particular, a shape in which the corners of the upper surface on the second substrate film side are chamfered, as shown on the right side of FIG. 4 , is preferred. Such a shape is advantageous in terms of ease of manufacturing a mold for forming the resin layer 18, ease of removing the mold when forming the resin layer 18, and prevention of damage to the formed resin layer 18.

[0078] In the wavelength conversion layer 16, the upper ends of the wall portions that form the recesses 18a of the resin layer 18 are separated from the second base film 14. Furthermore, the quantum dot-containing portions are provided not only in the recesses 18a of the resin layer 18 but also between the upper ends of the wall portions that are separated from the second base film 14 and the second base film 14. In the wavelength conversion member 10 of the illustrated example, as shown in Fig. 3, the upper ends of all the wall portions are separated from the second base film 14, and the quantum dot-containing portions are provided between the wall portions and the second base film 14. This configuration ensures good adhesion between the wavelength conversion layer 16 containing quantum dots 24 and the second base film on the upper side, i.e., the opening side of the recesses 18a of the resin layer 18.

[0079] As described below, in one example of manufacturing a wavelength conversion member, a coating liquid (resin layer-forming composition) that will become the resin layer is filled into a metal mold (die) having irregularities corresponding to the recesses and walls of the resin layer, a first substrate film is laminated so as to cover the coating liquid filled in the metal mold, the coating liquid that will become the resin layer is cured, and the metal mold is removed to form a laminate of the first substrate film and the resin layer. Next, the recesses of the resin layer are filled with the curable composition containing quantum dots, and a second substrate film is laminated on the resin layer so as to seal the curable composition filled in the resin layer. After that, the curable composition is cured to produce a wavelength conversion member in which a wavelength conversion layer having a resin layer and a quantum dot-containing portion is sandwiched between the first substrate film and the second substrate film.

[0080] The first substrate film and the resin layer can be laminated with sufficient adhesion because the resin layer is laminated in the form of a coating liquid and then the coating liquid is cured. Furthermore, the resin layer and the quantum dot-containing portion can be laminated with sufficient adhesion because the curable composition is filled into the recess and then cured. Regarding the wavelength conversion layer and the second substrate film, the region of the resin layer corresponding to the recess filled with the quantum dot-containing curable composition is filled with a fluorescent material in the form of a coating liquid and then cured, so good adhesion can be obtained. Furthermore, in the resin layer 18, the upper end of at least a portion of the wall portion constituting the recess 18a is separated from the second substrate film 14, and the quantum dot-containing portion is present not only in the recess 18a but also between the upper end of the wall portion separated from the second substrate film 14 and the second substrate film 14, thereby increasing the adhesion between the wavelength conversion layer 16 and the second substrate film 14. In the present invention and this specification, the term "between the upper end of the wall portion separating from the second base film 14" refers not only to the area directly above the wall portion whose upper end separates from the second base film 14, but also to the area between the recess 18a (its upper end) adjacent in the surface direction to the wall portion whose upper end separates from the second base film 14 and the second base film 14.

[0081] In the wavelength conversion layer 16, the wall portions of the resin layer 18 separated from the second base film 14 are not limited to a configuration in which the upper ends of all the wall portions are separated from the second base film 14 and the quantum dot-containing portion is provided therebetween, as shown in Fig. 3. The more wall portions of the resin layer 18 separated from the second base film 14, the stronger the adhesion between the wavelength conversion layer 16 and the second base film 14. In consideration of this point, in the wavelength conversion member 10, the upper ends of the wall portions of a portion corresponding to an area of ​​30% or more of the area of ​​the display unit of the display device in which the wavelength conversion member 10 is used are preferably separated from the second base film 14, and more preferably, the upper ends of all the wall portions are separated from the second base film 14 and the quantum dot-containing portion is in contact with the second base film 14 over the entire surface.

[0082] In the wavelength converting layer 16, in the wall portion whose upper end is separated from the second base film, the gap g (shortest distance) between the upper end (top) of the wall portion and the second base film 14 is not particularly limited as long as they are separated (see FIG. 5 ). Here, the gap g between the upper end of the wall portion and the second base film 14 is preferably 0.01 to 10 μm, more preferably 0.05 to 4 μm, and even more preferably 0.1 to 4 μm. By making the gap g between the upper end of the wall portion and the second base film 14 0.01 μm or more, the effect of the quantum dot-containing portion being present between the upper end of the wall portion and the second base film 14 can be fully exerted, and the adhesion between the wavelength converting layer 16 and the second base film 14 can be sufficiently increased. Furthermore, because the quantum dot-containing portion is more permeable to oxygen than the resin layer 18, if the gap g between the upper ends of the wall portions and the second base film 14 is too large, oxygen may permeate through the gap between the upper ends of the wall portions and the second base film 14, potentially degrading the quantum dots 24. In contrast, by setting the gap g between the upper ends of the wall portions and the second base film 14 to 10 μm or less, oxygen permeation through the gap between the upper ends of the wall portions and the second base film 14 can be sufficiently suppressed, preventing oxygen-induced degradation of the quantum dots 24. On the other hand, when a mixed layer 28 or an additional opaque layer 30 (described below) is present between the upper ends of the wall portions and the second base film 14, setting the gap g between the upper ends of the wall portions and the second base film 14 to 10 μm or less can prevent a decrease in luminance caused by the mixed layer 28 or additional opaque layer 30 being too thick. The gap g between the upper end of the wall portion and the second base film 14 can be determined, for example, by cutting the wall portion of the wavelength conversion member 10 with a microtome or the like to form a cross section, and observing the slice with a scanning electron microscope (SEM) or the like. Note that the "wall portion of the wavelength conversion member 10" refers to "a portion of the wavelength conversion member 10 that is not the recess 18a." The gap g can be determined as the arithmetic average of measurements at 10 randomly selected locations.

[0083] In the wavelength conversion layer 16, there are no particular limitations on the depth h of the recesses 18a in the resin layer 18 and the spacing t between adjacent quantum dot-containing portions (quantum dot-containing portions within adjacent recesses 18a). The depth h of the recesses in the resin layer 18 is preferably a depth that allows the thickness of the quantum dot-containing portion from the bottom of the recesses 18a to the second base film 14 (i.e., "depth h + gap g") to be 1 to 100 μm. The spacing t between adjacent quantum dot-containing portions is preferably 5 to 300 μm.

[0084] From the viewpoint of facilitating the achievement of the target chromaticity, the thickness (which can also be referred to as height) of the quantum dot-containing portion is preferably 1 μm or more. On the other hand, as the quantum dot-containing portion becomes thicker, the amount of light absorbed by the quantum dot-containing portion increases. Taking these points into consideration, the thickness of the quantum dot-containing portion from the bottom of the recess 18a to the second substrate film 14 is preferably 1 to 100 μm, more preferably 5 to 80 μm, and even more preferably 10 to 50 μm. The depth h of the recess 18a formed in the resin layer 18 and the thickness of the quantum dot-containing portion from the bottom of the recess 18a to the second substrate film 14 can be determined by cutting the recess 18a portion of the wavelength conversion member with a microtome or the like to form a cross section, irradiating the wavelength conversion layer 16 with excitation light to cause the quantum dots to emit light, and then observing the cross section with a confocal laser microscope or the like. The depth h and the thickness of the quantum dot-containing portion can be determined by the arithmetic mean of the measurements of 10 randomly selected quantum dot-containing portions.

[0085] Furthermore, the distance t between adjacent quantum dot-containing portions, i.e., the thickness of the wall of the resin layer 18 between adjacent quantum dot-containing portions (between adjacent recesses 18a), is preferably short (thin wall) so as to make the resin layer 18 invisible. On the other hand, from the viewpoints of strength and durability, the distance t between adjacent quantum dot-containing portions is preferably a certain value or greater. From these viewpoints, the distance t between adjacent quantum dot-containing portions is preferably 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 15 to 100 μm. The distance t between adjacent quantum dot-containing portions is the shortest distance between adjacent quantum dot-containing portions. This distance t can be determined by irradiating the wavelength conversion layer 16 with excitation light to cause the quantum dots to emit light, observing the surface from one side of the wavelength conversion member 10 using a confocal laser microscope or the like, and measuring the thickness of the wall of the resin layer 18 between adjacent quantum dot-containing portions. Furthermore, the distance t between adjacent quantum dot-containing portions can be calculated by taking the arithmetic mean of the distances at 20 randomly selected locations.

[0086] The shape, size, and arrangement pattern of the quantum dot-containing portions are not particularly limited and may be designed as appropriate. The design may take into account geometric constraints for spacing the quantum dot-containing portions apart in a planar view, as well as the tolerance for the width of non-luminescent regions that may occur during cutting. Furthermore, for example, when using a printing method as one of the methods for forming the quantum dot-containing portions, as described below, it is preferable that each occupied area be at least a certain size from the viewpoint of ease of printing. Note that the occupied area in this case refers to the occupied area in a planar view. Furthermore, a large minimum distance between adjacent quantum dot-containing portions, i.e., a large wall thickness, is preferable from the viewpoint of improving the mechanical strength of the wavelength conversion member. The shape, size, and arrangement pattern of the quantum dot-containing portions may be designed taking these points into consideration.

[0087] The ratio of the volume Vp of the quantum dot-containing portion to the volume Vb of the resin layer 18 can be any ratio. In one embodiment, the ratio "Vp / (Vp+Vb)" is preferably 0.1≦Vp / (Vp+Vb)<0.9, more preferably 0.2≦Vp / (Vp+Vb)<0.85, and even more preferably 0.3≦Vp / (Vp+Vb)<0.8. Here, the volume Vp of the quantum dot-containing portion and the volume Vb of the resin layer 18 are defined as the product of their respective areas and thicknesses when observed from a direction perpendicular to the main surface of the wavelength conversion member 10.

[0088] In the wavelength conversion layer, the quantum dot-containing portions between the upper ends of the walls forming the recesses 18a and the second base film 14, and between the recesses 18a (their upper ends) and the second base film 14, may contain a material that is impermeable to oxygen in addition to the quantum dot-containing portions. Figure 6 conceptually shows an example of this in a cross-sectional view of a wavelength conversion member. Note that the wavelength conversion member shown in Figure 6 includes the same parts as the wavelength conversion member 10 described above, so the same parts are denoted by the same reference numerals, and the description will mainly focus on the different parts. This also applies to the other drawings.

[0089] In the wavelength conversion member 10A shown in FIG. 6, the mixed layer 28 contains quantum dots and a material that is impermeable to oxygen. In the following description, the "material that is impermeable to oxygen" will also be referred to as an "oxygen-impermeable material." By having such a mixed layer 28, the wavelength conversion member 10A can prevent oxygen from penetrating into the quantum dot-containing portion between the upper end of the wall portion that forms the recess 18a and the second base film 14, thereby suppressing deterioration of the quantum dots 24 due to oxygen. In the present invention and this specification, the "oxygen-impermeable material" preferably means a material that, when a film having a thickness of 50 μm is formed from this material, has an oxygen transmission rate of 200 cc / (m ２ An oxygen-impermeable material is a material whose oxygen permeability is 20 cc / (m2) or less when a film having a thickness of 50 μm is formed from the material. ２ ·day·atm) or less, and ２It is more preferable that the oxygen-impermeable material is a material having a viscosity of not more than 1 / 2 day atm. Specific examples of the oxygen-impermeable material include various materials that can be used as the material for forming the resin layer 18. In particular, it is preferable that the mixed layer 28 contains, as the oxygen-impermeable material, a material that contains the same components as the material for forming the resin layer 18.

[0090] 6, the mixed layer 28 is not limited to being formed between the upper ends of the wall portions and the second base film 14 and on the top of the recess 18a. For example, the mixed layer 28 may not be formed in the recess 18a, but may be formed only between the upper ends of the wall portions that form the recess 18a and the second base film 14. Alternatively, the mixed layer 28 may be formed above and the quantum dot-containing portion below between the upper ends of the wall portions that form the recess 18a and the second base film 14.

[0091] There are no particular restrictions on the content of the oxygen-impermeable material in the mixed layer 28. The higher the content of the oxygen-impermeable material in the mixed layer 28, the more the quantum dots 24 can be prevented from being deteriorated by oxygen. On the other hand, if the content of the oxygen-impermeable material in the mixed layer 28 is high, the content of the quantum dots 24 will be relatively low, and the optical properties of the mixed layer 28, in other words, the optical properties of the wavelength conversion member 10A will be poor. Taking these points into consideration, the content of the oxygen-impermeable material in the mixed layer 28 is preferably, for example, 40 to 90 mass %, and more preferably 50 to 80 mass %.

[0092] Furthermore, there are no particular limitations on the thickness of the mixed layer 28. The content of quantum dots 24 in the mixed layer 28 is usually lower than that in the quantum dot-containing portion. Therefore, in consideration of the optical characteristics of the wavelength conversion member 10A, it is preferable that the thickness (vertical size) of the mixed layer 28 is thin. On the other hand, in terms of preventing deterioration of the quantum dots 24, it is preferable that the mixed layer 28 is thick. Considering these points, for example, when preventing deterioration of the quantum dots 24 is important, it is preferable that the entire area between the upper end of the wall portion forming the recess 18a and the second base film 14 be made into a mixed layer.

[0093] 7 , the wavelength conversion layer may have, in addition to the mixed layer 28, a layer (hereinafter referred to as "impermeable layer") 30 that does not contain quantum dots 24 and contains the same oxygen-impermeable material as the oxygen-impermeable material contained in the mixed layer 28 between the mixed layer 28 and the second base film 14. The presence of the impermeable layer 30 can further prevent deterioration of the quantum dots 24 due to oxygen permeating between the upper ends of the wall portions and the second base film 14.

[0094] There are no particular limitations on the thickness of the opaque layer 30 in the wavelength conversion member 10B. The opaque layer 30 does not contain quantum dots 24 and can be a layer formed only from an oxygen-impermeable material. Therefore, similar to the mixed layer 28, a thicker layer is advantageous for preventing deterioration of the quantum dots 24 due to oxygen. On the other hand, a thinner layer is preferable in terms of the optical properties of the wavelength conversion member. When the wavelength conversion member 10B has an opaque layer 30, the thickness of the opaque layer 30 can be appropriately set taking these points into consideration.

[0095] The mixed layer 28 and the impermeable layer 30 can be formed by various methods. As described above, the wavelength conversion member 10 can be manufactured by forming a resin layer 18 on the surface of the first substrate film 12, filling the recesses 18a of the resin layer 18 with the above-mentioned curable composition containing quantum dots, and then laminating a second substrate film 14 on the resin layer 18 so as to seal the curable composition filled in the resin layer 18, and curing the curable composition that will become the quantum dot-containing portion. As an example, in this manufacturing method, before laminating the second substrate film 14, a coating liquid containing an oxygen-impermeable material is applied to the surface of the second substrate film 14 that faces the resin layer 18. Then, the second substrate film 14 is laminated on the resin layer 18 with the coating liquid containing the oxygen-impermeable material facing the resin layer 18. As a result, the curable composition that will harden to become the quantum dot-containing portion and the coating liquid containing the oxygen-impermeable material are mixed between the upper end of the wall portion and the second substrate film 14. Thereafter, by curing the mixture of the coating liquid containing the oxygen-impermeable material and the curable composition, a mixed layer 28 containing the quantum dots and the oxygen-impermeable material can be formed between the upper end of the wall portion and the second substrate film 14. In this case, by adjusting the coating thickness of the coating liquid containing the oxygen-impermeable material applied to the second substrate film 14, it is possible to determine whether only the mixed layer 28 is formed, or whether both the mixed layer 28 and the impermeable layer 30 are formed. Specifically, by increasing the coating thickness of the coating liquid containing the oxygen-impermeable material, the impermeable layer 30 can be formed in addition to the mixed layer 28; the thicker the coating thickness of this coating liquid, the thicker the impermeable layer 30. This point will be described in detail later.

[0096] The wavelength conversion member 10 (10A, 10B) can have a configuration in which the wavelength conversion layer 16 having the resin layer 18 and the quantum dot-containing portion is sandwiched between a first base film 12 and a second base film 14. Furthermore, the wavelength conversion layer 10 may have a mixed layer 28 and / or an opaque layer 30 in addition to the resin layer 18 and the quantum dot-containing portion. It is preferable that both the first base film 12 and the second base film 14 are films that are impermeable to oxygen. In one embodiment of the wavelength conversion member 10, the first base film 12 has a configuration in which a barrier film 12b is laminated on a support 12a, and is laminated on the wavelength conversion layer 16 with the barrier film 12b facing the wavelength conversion layer 16. Similarly, the second base film 14 has a configuration in which a barrier film 14b is laminated on a support 14a, and is laminated on the wavelength conversion layer 16 with the barrier film 14b facing the wavelength conversion layer 16.

[0097] The barrier film 12b of the first base film 12 can be any of various known barrier films as long as it is oxygen impermeable. It preferably has at least one barrier layer, and more preferably is an organic-inorganic laminate barrier film having one or more combinations of a barrier layer and an organic layer that serves as an underlayer and / or protective layer for the barrier layer. The same applies to the barrier film 14b of the second base film 14. In the present invention and this specification, the term "barrier layer" refers to a layer containing at least one inorganic substance, and is preferably an inorganic layer. Details of the barrier layer will be described later.

[0098] The first base film 12 and the second base film 14 can have the same configuration except for the lamination position, so in the following explanation, the first base film 12 will be used as a representative example unless it is necessary to distinguish between the two.

[0099] In the wavelength conversion member 10 of the illustrated example, the barrier film 12b of the first base film (and the barrier film 14b of the second base film 14) has a three-layer laminate structure, including an underlying organic layer 34 formed on the surface of the support 12a (support 14a), a barrier layer 36 formed on the underlying organic layer 34, and a protective organic layer 38 formed on the barrier layer 36, as shown in the partially enlarged view A of FIG. 3 .

[0100] The surface of the support 12a, i.e., the underlying organic layer 34 of the barrier layer 36, is an underlying layer (undercoat layer) for properly forming the barrier layer 36. In an organic-inorganic laminated barrier layer, the barrier layer 36 is the portion that primarily exhibits barrier properties. Therefore, by forming the underlying organic layer 34 and then forming the barrier layer 36 thereon, the surface on which the barrier layer 36 is formed can be made appropriate, allowing the barrier layer 36 to be formed without defects and achieving high barrier properties. Note that while the illustrated example of the barrier film 12b has only one combination of the underlying organic layer 34 and the barrier layer 36, the barrier layer may have multiple combinations of the underlying organic layer 34 and the barrier layer 36. The more combinations of the underlying organic layer 34 and the barrier layer 36 there are, the higher the barrier properties that can be achieved.

[0101] The protective organic layer 38 formed on the surface of the barrier layer 36 is a protective layer (overcoat layer) that mainly protects the barrier layer 36, which exhibits barrier properties. The presence of this protective organic layer 38 prevents cracking and chipping of the barrier layer 36, and prevents deterioration of the barrier properties of the barrier film 12b due to damage to the barrier layer 36.

[0102] In the wavelength conversion member 10 shown in FIGS. 1 to 3 , the quantum dot-containing portion in the recess 18 a is cylindrical and circular in plan view. However, there are no particular limitations on the shape of the quantum dot-containing portion. For example, the quantum dot-containing portion may be a polygonal prism, such as a square in plan view as shown in FIG. 8 or a hexagonal (honeycomb structure) in plan view as shown in FIG. 9 , or may be a regular polygonal prism. In the above example, the bottom surface of the cylinder or polygonal prism is arranged parallel to the substrate film surface. However, the bottom surface does not necessarily have to be arranged parallel to the substrate film surface. Furthermore, the shape of each quantum dot-containing portion may be irregular.

[0103] When the boundary between the matrix 26 of the quantum dot-containing portion and the resin layer 18 is unclear, as shown in FIG. 10 , the line connecting the points outside the quantum dots 24e located at the outermost edge of the region where the quantum dots 24 are closely arranged (the side where the quantum dots 24 are not arranged) is regarded as the outline m of the quantum dot-containing portion (the boundary between the quantum dot-containing portion and the resin layer 18). The quantum dots can be identified by irradiating the wavelength conversion layer with excitation light to cause the quantum dots to emit light, and then observing the light with, for example, a confocal laser microscope, thereby identifying the position of the quantum dots, thereby identifying the outline m of the quantum dot-containing portion. In the present invention and this specification, the edges of cylinders and polygonal prisms, etc., may be meandering, as in the outline shown in FIG. 10 . Furthermore, in the above-described embodiment, the quantum dot-containing portions are arranged in a periodic pattern. However, a non-periodic pattern may be used as long as the multiple quantum dot-containing portions are arranged discretely, as long as the desired performance is not impaired. It is preferable that the quantum dot-containing portions are uniformly distributed throughout the entire wavelength conversion layer 16, as this results in a uniform in-plane distribution of brightness.

[0104] In order to obtain a sufficient amount of fluorescence, it is preferable that the area occupied by the quantum dot-containing portion is large. The quantum dots 24 in the quantum dot-containing portion may be of one type or of multiple types. Furthermore, the quantum dots 24 in one quantum dot-containing portion may be of one type, and among the multiple quantum dot-containing portions, a region containing first quantum dots and a region containing second quantum dots different from the first quantum dots may be arranged periodically or aperiodically. The types of quantum dots may be three or more. Details of quantum dots are as described above.

[0105] As described above, there are no particular limitations on the shape or arrangement pattern of the quantum dot-containing portions of the wavelength conversion layer. In either case, because the quantum dots are arranged discretely on the film surface, the quantum dots in the quantum dot-containing portions at the cut end may deteriorate. However, because the quantum dots in the portions other than the cut end are surrounded and sealed by resin along the film surface, performance degradation due to oxygen intrusion along the film surface can be suppressed.

[0106] Each component of the wavelength conversion layer will be described below.

[0107] As described above, the wavelength conversion member 10 shown in FIGS. 1 to 3 has a configuration in which a wavelength converting layer 16 is laminated on one film surface of a first base film 12, and a second base film 14 is further laminated on the wavelength converting layer 16, so that the wavelength converting layer 16 is sandwiched between the two base films.

[0108] (Resin Layer) The resin layer 18 can be formed, for example, by preparing, applying, and curing a resin layer-forming composition containing one or more polymerizable compounds. The resin layer 18 is preferably impermeable to oxygen. The resin layer 18 has an oxygen permeability of 10 cc / (m) in the shortest distance between adjacent quantum dot-containing portions across the wall portion that forms the recess 18a. ２ It is preferable that the oxygen permeability of the resin layer 18 in the shortest distance between adjacent quantum dot-containing portions is 10 cc / (m ２ ·day·atm) or less, and ２·day·atm) or less, and more preferably 1×10 －１ cc / (m ２ It is more preferable that the temperature is 1000°C or less (day·atm).

[0109] The desired shortest distance between the quantum dot-containing portions, i.e., the desired distance t between the quantum dot-containing portions (quantum dot-containing portions within the recesses 18 a), varies depending on the composition of the resin layer 18. Note that the shortest distance between adjacent quantum dot-containing portions in the resin layer 18 means the shortest distance within the film plane between adjacent quantum dot-containing portions when observed from the main surface of the wavelength conversion member.

[0110] The elastic modulus of the resin layer 18 is preferably 0.5 to 10 GPa, more preferably 1 to 7 GPa, and even more preferably 3 to 6 GPa. Setting the elastic modulus of the resin layer within the above range is preferable in order to prevent damage during formation of the resin layer while maintaining a desired oxygen permeability. The elastic modulus of the resin layer is measured by a method exemplified by JIS (Japanese Industrial Standards) K 7161, etc.

[0111] For the resin layer-forming composition (curable composition), reference can be made to paragraphs 0174 to 0179 of WO2018 / 186300.

[0112] (Substrate Film) As described above, the first substrate film 12 (and the second substrate film 14) can have a configuration in which the barrier film 12b is laminated on the support 12a. The barrier film 12b (and the barrier film 14b) can have an underlying organic layer 34, a barrier layer 36, and a protective organic layer 38. Such a first substrate film 12 is laminated on the wavelength converting layer 16 with the barrier film 12b facing the wavelength converting layer 16. In this configuration, the support 12a can improve the strength of the wavelength converting member 10 and facilitate film formation. However, in the present invention and this specification, the first substrate film (and the second substrate film) is not limited to a configuration having such a support 12a and a barrier film 12b. Various film-like materials can be used as long as they have at least a support and a barrier layer. In the present invention and this specification, the terms "film-like" and "film" are used synonymously with "sheet-like," and "sheet," respectively.

[0113] The first base film 12 preferably has a total light transmittance of 80% or more, more preferably 85% or more, in the visible light region. The visible light region is the wavelength region of 380 to 780 nm, and the total light transmittance is the arithmetic average of the light transmittance across the visible light region.

[0114] The first base film 12 has an oxygen permeability of 1 cc / (m ２ The oxygen permeability of the first base film 12 is preferably 0.1 cc / (m ２ ·day·atm) or less, more preferably 0.01 cc / (m ２ ·day·atm) or less, and more preferably 0.001 cc / (m ２ ・day・atm) or less.

[0115] The first base film 12 preferably has a water vapor barrier property that blocks moisture (water vapor) in addition to a gas barrier property that blocks oxygen. The moisture permeability (water vapor permeability) of the first base film 12 is 0.10 g / (m ２ ·day·atm) or less, and 0.01 g / (m２ ·day·atm) or less is more preferable.

[0116] (Support) The support 12a (and support 14a) is preferably a flexible, band-shaped support that is transparent to visible light. Here, "transparent to visible light" means that the light transmittance in the visible light region is 80% or more, preferably 85% or more. The light transmittance used as a measure of transparency can be calculated by the method described in JIS K 7105, i.e., by measuring the total light transmittance and the amount of scattered light using an integrating sphere light transmittance measuring device and subtracting the diffuse transmittance from the total light transmittance. For flexible supports, see paragraphs 0046 to 0052 of JP 2007-290369 A and paragraphs 0040 to 0055 of JP 2005-096108 A.

[0117] Specific examples of the support 12a include a polyethylene terephthalate (PET) film, a film made of a polymer having a cyclic olefin structure, and a polystyrene film.

[0118] The thickness of the support 12a is preferably 10 to 500 μm, more preferably 20 to 400 μm, from the viewpoint of improving the impact resistance of the wavelength conversion member. When the concentration of quantum dots contained in the wavelength conversion layer 16 is reduced or the thickness of the wavelength conversion layer 16 is reduced, in a configuration in which the retroreflection of light is increased, a lower absorptance of light with a wavelength of 450 nm is more preferable. From this viewpoint, the thickness of the support 12a is preferably 40 μm or less, more preferably 25 μm or less.

[0119] (Barrier Layer) As described above, a "barrier layer" is a layer containing at least one inorganic substance, and is preferably an inorganic layer. In the present invention and this specification, an "inorganic layer" is a layer containing an inorganic substance as a main component. The main component refers to the component that accounts for the largest proportion by mass among the components constituting the layer. The inorganic layer may be a layer in which the content of the inorganic substance is 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more. Alternatively, the inorganic layer may be a layer composed solely of an inorganic substance. Here, a layer composed solely of an inorganic substance refers to a layer containing only an inorganic substance, excluding impurities that are inevitably mixed in during the manufacturing process. The inorganic layer may contain only one type of inorganic substance, or two or more types of inorganic substances.

[0120] Examples of inorganic substances constituting the inorganic layer include metals, or various inorganic compounds such as inorganic oxides, nitrides, and oxynitrides. Elements constituting the inorganic substance are preferably silicon, aluminum, magnesium, titanium, tin, indium, and cerium, and one or more of these may be contained. Specific examples of inorganic substances include silicon oxide, aluminum oxide, magnesium oxide, titanium oxide, tin oxide, indium oxide alloy, silicon oxynitride, silicon nitride, aluminum nitride, and titanium nitride. Furthermore, metal films, such as aluminum films, silver films, tin films, chromium films, nickel films, and titanium films, may be provided as the inorganic layer.

[0121] The first base film 12 (and the second base film 14) has a barrier film 12b on one surface of the support 12a. As described above, various known barrier films can be used as the barrier film 12b. It is preferable that the barrier film has at least one inorganic layer, and an organic-inorganic laminate barrier film having one or more combinations of an inorganic layer and an organic layer underlying the inorganic layer is more preferable. In the wavelength conversion member 10 of the illustrated example, the barrier film 12b of the first base film has a three-layer laminate configuration, as shown in the partial enlarged view A of FIG. 3 , including a base organic layer 34 formed on the surface of the support 12a, a barrier layer 36 formed on the base organic layer 34, and a protective organic layer 38 formed on the barrier layer 36. In the following description, when there is no need to distinguish between the base organic layer 34 and the protective organic layer 38, they will also be collectively referred to as "organic layer."

[0122] The barrier layer 36 is preferably a layer having gas barrier properties that block oxygen. Specifically, the oxygen permeability of the inorganic layer is 1 cc / (m ２ It is also preferable that the inorganic layer has a water vapor barrier property that blocks water vapor.

[0123] The thickness of the barrier layer 36 is preferably 1 to 500 nm, more preferably 5 to 300 nm, and even more preferably 10 to 150 nm. When the thickness of the barrier layer 36 is within the above range, reflection in the barrier layer 36 can be suppressed while achieving good barrier properties, and a laminate film with higher light transmittance can be provided.

[0124] The organic layer (underlying organic layer 34 and protective organic layer 38) refers to a layer whose main component is an organic material, and preferably a layer in which the organic material accounts for 50% by mass or more, further 80% by mass or more, and particularly 90% by mass or more.

[0125] For the organic layer, reference can be made to paragraphs 0020 to 0042 of JP-A No. 2007-290369 and paragraphs 0074 to 0105 of JP-A No. 2005-096108. In one embodiment, the organic layer preferably contains a cardo polymer. This is because the adhesion between the organic layer and adjacent layers, particularly with inorganic layers, is strengthened, thereby achieving even better gas barrier properties. For details about the cardo polymer, reference can be made to paragraphs 0085 to 0095 of JP-A No. 2005-096108.

[0126] The thickness of the organic layer is preferably 0.05 to 10 μm, more preferably 0.1 to 10 μm. The organic layer can be formed by a wet coating method or a dry coating method.

[0127] For details of the barrier layer, reference can be made to paragraphs 0193 to 0196 of WO2018 / 186300. For other details of the barrier layer and the organic layer, reference can be made to the descriptions in JP2007-290369A, JP2005-096108A, and US2012 / 0113672A1.

[0128] In the wavelength conversion member, the organic layer may be laminated between the support and the barrier layer as an underlayer for the barrier layer, or may be laminated between the barrier layer and the wavelength conversion layer as a protective layer for the barrier layer. In addition, when the wavelength conversion member has two or more barrier layers, the organic layer may be laminated between the barrier layers.

[0129] The first substrate film 12 (and the second substrate film 14) may have a roughness-imparting layer that imparts a roughness structure to the surface opposite to the surface on the wavelength converting layer 16 side. The first substrate film 12 preferably has a roughness-imparting layer, since this can improve the blocking properties and / or slip properties of the substrate film. The roughness-imparting layer is preferably a layer containing particles. Examples of the particles include inorganic particles such as silica, alumina, and metal oxides, and organic particles such as crosslinked polymer particles. The roughness-imparting layer is preferably provided on the surface of the substrate film opposite to the wavelength converting layer, and may be provided on both surfaces.

[0130] The wavelength conversion member 10 can have a light-scattering function to efficiently extract fluorescence from the quantum dots to the outside. The light-scattering function may be provided within the wavelength conversion layer 16, or a layer having the light-scattering function may be provided separately as the light-scattering layer. The light-scattering layer may be provided on the surface of the first base film 12 and / or the second base film 14 facing the wavelength conversion layer 16, or on the surface of the first base film 12 and / or the second base film 14 opposite to the wavelength conversion layer 16. When the roughness-imparting layer is provided, it is preferable that the roughness-imparting layer also function as a light-scattering layer.

[0131] (Mixed Layer, Impermeable Layer) As described above, the mixed layer 28 contains the quantum dots 24 contained in the quantum dot-containing portion 20. The impermeable layer 30 can be a layer made of an oxygen-impermeable material that does not contain the quantum dots 24. As the oxygen-impermeable material, various materials that can be used as materials for forming the resin layer 18 can be used. In particular, it is preferable that the mixed layer 28 and the impermeable layer 30 contain, as the oxygen-impermeable material, the same polymerizable compound as the polymerizable compound used to form the resin layer 18.

[0132] (Method of Manufacturing Wavelength Conversion Member) Next, an example of a manufacturing process for a wavelength conversion member will be described with reference to conceptual diagrams of FIGS. 11 and 12. FIG.

[0133] First, a resin layer-forming composition L1 for forming the resin layer 18 is prepared by mixing a polymerizable compound with various components, such as a polymerization initiator, inorganic particles, and light-scattering particles, as needed. The above-mentioned curable composition L2 containing quantum dots is also prepared. Furthermore, a mold M having a concavo-convex pattern corresponding to the recesses 18a and wall portions of the resin layer 18, as well as a first substrate film 12 and a second substrate film 14, are prepared to form the resin layer 18.

[0134] After these are prepared, first, as shown in the first and second rows of Fig. 11, the prepared resin layer-forming composition L1 is filled into the prepared mold M, and then, as shown in the third row of Fig. 11, a first base film 12 is laminated onto the mold M so as to cover the entire surface of the resin layer-forming composition L1. Next, the resin layer-forming composition L1 is cured, for example, by ultraviolet irradiation or the like, to form a resin layer 18, and as shown in the fourth row of Fig. 11, the mold M is removed from the resin layer 18. This forms a laminate in which the resin layer 18 is laminated on one surface of the first base film 12, with the bottoms of the recesses 18a facing the first base film 12.

[0135] After forming a laminate of the first substrate film 12 and the resin layer 18, the recess 18a is filled with the quantum dot-containing curable composition L2 (quantum dot-containing curable composition) as shown in the first row of FIG. 12 . At this time, the quantum dot-containing curable composition L2 is filled into the recess 18a so that the quantum dot-containing curable composition L2 rises above the upper ends of the walls of the resin layer 18, utilizing the surface tension and viscosity of the curable composition L2. Next, as shown in the second row of FIG. 12 , the second substrate film 14 is laminated so as to entirely cover and seal the quantum dot-containing curable composition L2. In this case, the pressure of the second substrate film 14 can be adjusted to adjust the gap between the upper ends of the walls of the resin layer 18 and the second substrate film 14. For example, when the second substrate film 14 is laminated using a laminator, the pressure of the laminator can be adjusted to adjust the gap between the upper ends of the walls of the resin layer 18 and the second substrate film 14. Thereafter, the quantum dot-containing curable composition L2 is cured by, for example, light irradiation to form a quantum dot-containing portion, and a wavelength conversion layer 16 having the quantum dot-containing portion and the resin layer 18 is sandwiched between a first substrate film 12 and a second substrate film 14 to produce a wavelength conversion member 10, as shown in the third row of Fig. 12. When the quantum dot-containing curable composition L2 is cured by light irradiation, the effective irradiation dose calculated by the following formula is set to 350 mJ / cm, from the viewpoint of controlling the ΔTg and ESR intensity within the above-described ranges. ２ It is preferable that the dose is 1000 mJ / cm or more. ２ More preferably, it is 1400 mJ / cm or more. ２Such an effective dose is, for example, 10,000 mJ / cm. ２ Effective irradiation dose = irradiation dose (unit: mJ / cm ２ ) × transmittance of support at center wavelength of light source spectrum [%] / 100

[0136] The light source used for light irradiation for the curing treatment is preferably a UV-LED (ultraviolet-light emitting diode), and more preferably a UV-LED with a peak wavelength half-width of 30 nm or less. The use of a UV-LED allows for efficient activation of the polymerization initiator. Furthermore, the surface temperature of the irradiated object is less likely to increase, and thermal deformation of the support can be suppressed, enabling light irradiation with a high effective dose.

[0137] Furthermore, it is preferable to carry out the light irradiation in a nitrogen atmosphere, since inhibition caused by oxygen can be suppressed and curing can be promoted.

[0138] When forming a mixed layer 28 or an additional opaque layer 30 as in the wavelength conversion member 10A shown in FIG. 6 and the wavelength conversion member 10B shown in FIG. 7, prior to laminating the second substrate film 14 shown in the second row of FIG. 12, a coating liquid L3 containing an oxygen-impermeable material is applied to one surface of the second substrate film 14, as conceptually shown in FIG. 13. Then, as shown in the second row of FIG. 12, the second substrate film 14 is laminated so that the coated surface of the coating liquid L3 faces the quantum dot-containing curable composition L2 and covers and seals the entire surface of the quantum dot-containing curable composition L2. This causes the quantum dot-containing curable composition L2 and the coating liquid L3 containing the oxygen-impermeable material to be mixed. Then, by curing the quantum dot-containing curable composition L2 and the coating liquid L3 containing the oxygen-impermeable material, a wavelength conversion member having a mixed layer 28 or an additional opaque layer 30 together with a quantum dot-containing portion can be produced. In this case, as described above, by adjusting the coating thickness of the coating liquid L3 containing the oxygen-impermeable material onto the second base film 14, it is possible to determine whether only the mixed layer 28 is formed, or whether both the mixed layer 28 and the impermeable layer 30 are formed. Specifically, when the coating thickness of the coating liquid L3 containing the oxygen-impermeable material onto the second base film 14 is thin, only the mixed layer 28 can be formed, and by increasing the coating thickness of the coating liquid L3 containing the oxygen-impermeable material onto the second base film 14, both the mixed layer 28 and the impermeable layer 30 can be formed. Furthermore, the thicker the coating thickness of the coating liquid L3, the thicker the impermeable layer 30.

[0139] In the wavelength conversion layer, the method for forming the recesses 18a in the resin layer 18 is not limited to the method shown in Figure 11, and various known methods for forming film-like objects with recesses and projections can be used. For example, a method of first applying a resin layer-forming composition L1 to a first substrate film 12, pressing a mold M against the resin layer-forming composition L1, and then curing the resin layer-forming composition L1, a method of laminating the first substrate film 12 and the mold M, filling the space between the first substrate film 12 and the mold M with the resin layer-forming composition L1, and then curing the resin layer-forming composition L1, and the like can be exemplified. In addition to these methods, a method of forming a planar resin layer and then etching the resin layer 18 having recesses 18a, a method of forming the resin layer 18 having recesses 18a using a printing method such as an inkjet method or a dispenser method, and the like can also be used.

[0140] In one embodiment, the wavelength converting layer can be a cured product obtained by curing the curable composition into a film. This type of wavelength converting layer can be considered a continuous layer in which the cured product containing quantum dots is continuous. In contrast, in the wavelength converting layer described above, the cured product containing quantum dots is present as a discontinuous layer.

[0141] For the method for producing a wavelength conversion member having a wavelength conversion layer that is a cured product obtained by curing the curable composition into a film, see, for example, paragraphs 0127 to 0155 and FIGS. 2 and 3 of WO2018 / 016589.

[0142] [Light-emitting device] One aspect of the present invention relates to a light-emitting device including the wavelength conversion member and a light source.

[0143] In one embodiment, the light emitting device may be a backlight unit, which may serve as a light emitting device for a liquid crystal display device, for example.

[0144] An example of a backlight unit will be described below with reference to the drawings. Fig. 14 is a schematic diagram showing the general configuration of a backlight unit.

[0145] As shown in FIG. 14, the backlight unit 50 emits primary light (blue light L Ｂ14 shows a planar light source 52C including a light source 52A that emits primary light, a light guide plate 52B that guides the primary light emitted from the light source 52A, and an optical waveguide 52B that guides and emits the primary light, a wavelength conversion member 54 that is disposed on the planar light source 52C, a reflector 56A that is disposed opposite the wavelength conversion member 54 with the planar light source 52C interposed therebetween, and a retroreflective member 56B. Although the reflector 56A, the light guide plate 52B, the wavelength conversion member 54, and the retroreflective member 56B are shown separated from one another in the drawing, they may actually be formed in close contact with one another.

[0146] The wavelength conversion member 54 converts the primary light L emitted from the surface light source 52C into Ｂ The fluorescent light is emitted using at least a part of the fluorescent light as excitation light, and the secondary light (green light L Ｇ , red light L Ｒ ) and the primary light L that has passed through the wavelength conversion member 54 Ｂ For example, the wavelength conversion member 54 emits blue light L Ｂ By irradiating the green light L Ｇ Quantum dots that emit red light L Ｒ The wavelength conversion member 10 is configured by sandwiching a wavelength conversion layer 16 containing quantum dots that emit light of a wavelength other than 100 nm between a first base film 12 and a second base film 14.

[0147] In FIG. 14, L emitted from the wavelength conversion member 54 Ｂ , L Ｇ and L Ｒ The light beams are incident on the retroreflective member 56B, and each incident light beam is repeatedly reflected between the retroreflective member 56B and the reflector 56A, and can pass through the wavelength conversion member 54 many times. As a result, the wavelength conversion member 54 can convert a sufficient amount of excitation light (blue light L Ｂ ) is absorbed by the quantum dots 24 in the wavelength-converting layer 16, resulting in a sufficient amount of fluorescent light (L Ｇ , L Ｒ ) is emitted, and white light L Ｗ is materialized and emitted.

[0148] From the viewpoint of achieving high brightness and high color reproducibility, it is preferable to use a multi-wavelength light source as the backlight unit 50. For example, it is preferable to emit blue light having a central emission wavelength in the wavelength band of 430 to 480 nm and a peak emission intensity with a half-width of 100 nm or less, green light having a central emission wavelength in the wavelength band of 500 to 600 nm and a peak emission intensity with a half-width of 100 nm or less, and red light having a central emission wavelength in the wavelength band of 600 to 680 nm and a peak emission intensity with a half-width of 100 nm or less.

[0149] From the viewpoint of further improving brightness and color reproducibility, the wavelength band of the blue light emitted by the backlight unit 50 is more preferably 440 to 460 nm. From the same viewpoint, the wavelength band of the green light emitted by the backlight unit 50 is preferably 520 to 560 nm, and more preferably 520 to 545 nm. From the same viewpoint, the wavelength band of the red light emitted by the backlight unit 50 is more preferably 610 to 640 nm. From the same viewpoint, the half-width of the emission intensity of each of the blue light, green light, and red light emitted by the backlight unit 50 is preferably 80 nm or less, more preferably 50 nm or less, even more preferably 40 nm or less, and particularly preferably 30 nm or less. Among these, it is particularly preferable that the half-width of each emission intensity of the blue light is 25 nm or less.

[0150] The light source 52A can be, for example, a blue light-emitting diode that emits blue light having a central emission wavelength in the wavelength band of 430 to 480 nm. Alternatively, an ultraviolet light-emitting diode that emits ultraviolet light may be used. In addition to a light-emitting diode, a laser light source or the like can also be used as the light source 52A. When a light source that emits ultraviolet light is provided, the wavelength conversion layer 16 of the wavelength conversion member 54 may contain quantum dots that emit blue light, quantum dots that emit green light, and quantum dots that emit red light when irradiated with ultraviolet light.

[0151] As shown in Fig. 14, the surface light source 52C may be a surface light source including a light source 52A and a light guide plate 52B that guides and emits the primary light emitted from the light source 52A, or a surface light source in which the light sources 52A are arranged in a plane parallel to the wavelength conversion member 54 and a diffusion plate is provided instead of the light guide plate 52B. The former surface light source is generally called an edge light type, and the latter surface light source is generally called a direct type. Note that the above description was given using an example in which a surface light source is used as the light source. However, light sources other than surface light sources can also be used as the light source.

[0152] <Configuration of Backlight Unit> In Fig. 14, an edge-light type backlight unit having a light guide plate, a reflector, and other components has been described. However, the backlight unit may be configured as a direct type. A known light guide plate can be used.

[0153] The reflector 56A is not particularly limited, and known reflectors can be used, see, for example, Japanese Patent Nos. 3,416,302, 3,363,565, 4,091,978, and 3,448,626.

[0154] The retroreflective member 56B may be composed of a known diffusion plate or diffusion sheet, a prism sheet (e.g., the BEF series manufactured by Sumitomo 3M), a light guide, etc. For the configuration of the retroreflective member 56B, reference can be made to Japanese Patent No. 3,416,302, Japanese Patent No. 3,363,565, Japanese Patent No. 4,091,978, Japanese Patent No. 3,448,626, etc.

[0155] [Liquid Crystal Display Device] One aspect of the present invention relates to a liquid crystal display device including the above-described light-emitting device and a liquid crystal cell.

[0156] An example of a liquid crystal display device will be described below with reference to the drawings. Figure 15 is a schematic diagram showing the general configuration of a liquid crystal display device.

[0157] As shown in FIG. 15, a liquid crystal display device 60 includes a backlight unit 50 and a liquid crystal cell unit 62 disposed opposite the backlight unit on the retroreflective member side.

[0158] As shown in Figure 15, the liquid crystal cell unit 62 has a configuration in which a liquid crystal cell 64 is sandwiched between polarizing plates 68 and 70, and the polarizing plates 68 and 70 have polarizers 72 and 74 whose main surfaces are protected by polarizing plate protective films 76 and 78, and 82 and 84, respectively.

[0159] There are no particular limitations on the liquid crystal cell 64, polarizing plates 68 and 70, and other components that make up the liquid crystal display device 60, and products produced by known methods or commercially available products can be used. Of course, it is also possible to provide known intermediate layers, such as adhesive layers, between the layers.

[0160] The driving mode of the liquid crystal cell 64 is not particularly limited, and various modes such as twisted nematic (TN), supertwisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), and optically compensated bend cell (OCB) can be used. The liquid crystal cell is preferably in VA mode, OCB mode, IPS mode, or TN mode. However, it is not limited to these. An example of the configuration of a VA mode liquid crystal display device is the configuration shown in FIG. 2 of JP 2008-262161 A. However, there are no particular limitations on the specific configuration of the liquid crystal display device, and any known configuration can be used.

[0161] The liquid crystal display device 60 may further include, as necessary, additional functional layers such as an optical compensation member for performing optical compensation, an adhesive layer, etc. The liquid crystal display device 60 may also include a surface layer such as a forward scattering layer, a primer layer, an antistatic layer, an undercoat layer, etc., arranged in addition to (or instead of) a color filter substrate, a thin-layer transistor substrate, a lens film, a diffusion sheet, a hard coat layer, an antireflection layer, a low-reflection layer, an antiglare layer, etc.

[0162] The polarizing plate 68 on the backlight unit 50 side may have a retardation film as a polarizing plate protective film 78 on the liquid crystal cell 64 side. As such a retardation film, a known cellulose acylate film or the like can be used.

[0163] The present invention will be explained in more detail below based on examples. The materials, amounts used, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. Unless otherwise specified, "%" in the following descriptions indicates % by mass.

[0164] [Example 1] <Preparation of wavelength conversion member> (Preparation of barrier film) As a first base film and a second base film, base films in which an underlying organic layer, an inorganic layer (barrier layer), and a protective organic layer were formed on a support made of polyethylene terephthalate (PET) were prepared as follows.

[0165] A PET film (Cosmoshine A4300, manufactured by Toyobo Co., Ltd., thickness 23 μm) was used as a support, and an underlying organic layer, an inorganic layer (barrier layer), and a protective organic layer were sequentially formed on one side of the support by the following procedure.

[0166] Formation of Underlayer Organic Layer Trimethylolpropane triacrylate (TMPTA manufactured by Daicel Allnex Corporation) and a photopolymerization initiator (ESACURE KTO46 manufactured by Lamberti Corporation) were prepared and weighed out to a mass ratio of 95:5. These were dissolved in methyl ethyl ketone to prepare a coating solution with a solids concentration of 15% for forming the underlayer organic layer. This coating solution was applied to a support (PET film) in a roll-to-roll manner using a die coater, and passed through a drying zone at a temperature of 50°C for 3 minutes. Thereafter, ultraviolet light was irradiated under a nitrogen atmosphere (cumulative irradiation dose of approximately 600 mJ / cm). ２ The coating solution was cured by heating, and the film was then wound up. The thickness of the underlying organic layer formed on the support was 1 μm.

[0167] Formation of Inorganic Layer (Barrier Layer) Next, a silicon nitride film was formed as an inorganic layer on the surface of the underlying organic layer using a roll-to-roll CVD (Chemical Vapor Deposition) apparatus. Silane gas (flow rate 160 sccm (Standard Cubic Centimeter per Minute)), ammonia gas (flow rate 370 sccm), hydrogen gas (flow rate 590 sccm), and nitrogen gas (flow rate 240 sccm) were used as source gases. A high-frequency power source with a frequency of 13.56 MHz was used as the power source. The film formation pressure was 40 Pa (Pascal), and the final film thickness was 50 nm.

[0168] Formation of Protective Organic Layer Furthermore, a protective organic layer was laminated on the surface of the inorganic layer. 95.0 parts by mass of a urethane-skeleton acrylate polymer (Acrit 8BR930 manufactured by Taisei Fine Chemical Co., Ltd.) and 5.0 parts by mass of a photopolymerization initiator (IRGACURE 184 manufactured by BASF) were weighed and dissolved in methyl ethyl ketone to prepare a coating solution with a solids concentration of 15% for forming the protective organic layer. This coating solution was directly applied to the surface of the inorganic layer by roll-to-roll using a die coater and passed through a drying zone at a temperature of 100°C for 3 minutes. Thereafter, the film was wrapped around a heat roll heated to a surface temperature of 60°C and transported while being irradiated with ultraviolet light (cumulative exposure dose of approximately 600 mJ / cm). ２ The protective organic layer formed on the support had a thickness of 0.1 μm.

[0169] In this way, substrate films to be used as the first substrate film and the second substrate film were prepared. The oxygen permeability of this substrate film was measured using an OX-TRAN 2 / 20 manufactured by MOCON Corporation under conditions of a measurement temperature of 23°C and a relative humidity of 90%, and the oxygen permeability was 4.0 × 10 －３ cc / (m ２ ・day・atm) or less.

[0170] (Formation of Resin Layer) Preparation of Resin Layer-Forming Composition A The following components were charged into a tank and mixed to prepare a resin layer-forming composition A.

[0171] Resin layer-forming composition A: 42 parts by weight of urethane (meth)acrylate (U-4HA manufactured by Shin-Nakamura Chemical Co., Ltd.), 42 parts by weight of tricyclodecane dimethanol diacrylate (A-DCP manufactured by Shin-Nakamura Chemical Co., Ltd.), 15 parts by weight of plate alumina (inorganic layer compound: Seraph 05070 manufactured by Kinseimatic Co., Ltd.), 1 part by weight of photopolymerization initiator (Omnirad TPO manufactured by IGM Resins B.V.)

[0172] Formation of Resin Layer A mold was prepared as a mold for forming a resin layer, having convex portions corresponding to the concave portions of the resin layer and concave portions corresponding to the wall portions. Here, the concave portions of the resin layer (convex portions of the mold) were regular hexagonal with sides of 125 μm, forming a honeycomb pattern. The depth h of the concave portions (height of the convex portions of the mold) was 40 μm, and the spacing between the concave portions (spacing t between the convex portions of the mold (i.e., the thickness of the wall portions)) was 50 μm (see FIG. 5). The bottom corners of the concave portions of the mold M that became the wall portions were curved with a radius of curvature of 10 μm. The resin layer-forming composition A prepared previously was filled so as to completely fill the concave portions of the mold. Next, a first substrate film (barrier film) was laminated on the mold so as to completely cover the resin layer-forming composition A, and the resin layer-forming composition was photocured while pressed against the mold at a pressure of 0.5 MPa using a laminator. The resin layer-forming composition A was photocured by irradiating ultraviolet light from the first substrate film side at a dose of 500 mJ / cm using a 200 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.). ２ The irradiation was carried out. Thereafter, the mold was removed, and a laminate was produced in which a resin layer was laminated on the first substrate film (see FIG. 11). Using the above resin layer-forming composition A, a film having a thickness of 50 μm was formed under exactly the same conditions. In other words, this film corresponds to the 50 μm-thick wall portion of the resin layer. The oxygen permeability of this film was measured in the same manner as above, and the oxygen permeability was found to be 8 cc / (m ２ ·day·atm), and for the resin layer-forming composition B described later, 1 cc / (m ２ ·day·atm), and for the resin layer-forming composition C described later, 1 cc / (m ２The elastic modulus of the cured resin layer was measured in accordance with JIS K 7161, and the elastic modulus was 4.2 GPa for resin layer-forming composition A, 2.5 GPa for resin layer-forming composition B, and 2.5 GPa for resin layer-forming composition C.

[0173] (Preparation of wavelength conversion member) Preparation of quantum dot-containing curable composition The following components were charged into a tank and mixed to prepare a quantum dot-containing curable composition. In the preparation, a toluene dispersion of quantum dot 1 (emission maximum: 520 nm) and a toluene dispersion of quantum dot 2 (emission maximum: 630 nm) were mixed and used in amounts such that the total content of quantum dots in the curable composition was 2.0%. Quantum dots 1 and 2 are the following semiconductor nanoparticles having a core-shell structure (core: InP / shell: ZnS). Quantum dot 1: INP530-10 manufactured by NN-labs Quantum dot 2: INP620-10 manufactured by NN-labs

[0174] Quantum dot toluene dispersion: 2.0% as quantum dots Component A: See Table 1 for type and content Component B: See Table 1 for type and content Component C: See Table 1 for type and content Monofunctional acrylate: See Table 1 for type and content Light scattering particles: See Table 1 for type and content Photopolymerization initiator: See Table 1 for type and content Phenol-based compound: See Table 1 for type and content

[0175] Component A is a first (meth)acrylate, component B is a multifunctional thiol, and component C is a second (meth)acrylate.

[0176]

[0049] The quantum dot-containing curable composition was filled into the recesses of the resin layer of the laminate of the first substrate film and resin layer prepared previously, completely filling the recesses. A second substrate film (barrier film) was then laminated onto the resin layer so as to completely cover the quantum dot-containing curable composition, and the quantum dot-containing curable composition was photocured while being pressed against the resin layer with a laminator at a pressure of 0.3 MPa. This formed a wavelength conversion layer in which quantum dot-containing portions (cured products obtained by curing the quantum dot-containing curable composition) were formed in the recesses discretely formed in the resin layer, thereby producing a wavelength conversion member (see FIG. 12). The quantum dot-containing curable composition was photocured using a 365 nm UV-LED irradiator (center wavelength: 365 nm) manufactured by Acroedge Co., Ltd., by irradiating ultraviolet light from the first substrate film side in a nitrogen atmosphere at the dose shown in Table 2.

[0177] The prepared wavelength conversion member was cut with a microtome, and the cross section of the slice was observed with an SEM. As a result, this wavelength conversion member had a gap of 0.5 μm between the upper end of the wall portion of the resin layer and the second base film. In addition, excitation light with a wavelength of 405 nm was irradiated, and the distribution of light-emitting particles in the cross section was observed with a confocal laser microscope (Leica TCS SP5) using a 50x objective lens. As a result, it was confirmed that in this wavelength conversion member, a 0.5 μm thick layer (quantum dot-containing layer) containing quantum dots similar to those in the quantum dot-containing portions formed in the recesses of the resin layer was formed between the upper end of the wall portion of the resin layer and the second base film.

[0178] [Examples 2 to 15, Comparative Examples 1 to 6] Wavelength conversion members were produced by the method described for Example 1, except that the items shown in Table 1 and / or the irradiation doses shown in Table 2 were changed as shown in each table.

[0179] For each of Examples 1 to 15 and Comparative Examples 1 to 6, the effective irradiation dose in the light irradiation for photocuring the quantum dot-containing curable composition was the value shown in Table 2.

[0180]

[0181] The components of the resin layer forming composition B and the resin layer forming composition C shown in Table 1 are as follows.

[0182] Resin layer forming composition B Triallyl isocyanurate (Taikyu manufactured by Mitsubishi Chemical Corporation): 27.8 parts by mass Pentaerythritol tetrakis(3-mercaptopropionate) (PEMP manufactured by SC Organic Chemicals Co., Ltd.): 41.8 parts by mass Light scattering particles (Advanced Alumina AA-1.5 manufactured by Sumitomo Chemical Co., Ltd.): 30.0 parts by mass Photopolymerization initiator (Irgacure TPO manufactured by BASF): 0.35 parts by mass Pyrogallol (Pyrogallol manufactured by TCI): 0.035 parts by mass

[0183] Resin layer forming composition C Triallyl isocyanurate (Mitsubishi Chemical Corporation, Taik): 26.2 parts by mass Pentaerythritol tetrakis (3-mercaptopropionate) (SC Organic Chemical Co., Ltd., PEMP): 39.3 parts by mass Light scattering particles (Sumitomo Chemical Co., Ltd., Advanced Alumina AA-1.5): 30.0 parts by mass Viscoat #260 (1.9-NDDA) (Osaka Organic Chemical Industry Co., Ltd.): 2.97 parts by mass Adeka Polyether G-700 (Adeka): 0.99 parts by mass Solsperse 36000 (Lubrizol Japan Co., Ltd.): 0.10 parts by mass Photopolymerization initiator (BASF Corporation, Irgacure TPO): 0.35 parts by mass Pyrogallol (TCI Corporation, Pyrogallol): 0.035 parts by mass

[0184] Details of the various components shown in Table 1 are as follows: NK Ester A-DCP: tricyclodecane dimethanol diacrylate manufactured by Shin-Nakamura Chemical Co., Ltd. IBXA: isobornyl acrylate manufactured by Osaka Organic Chemical Industry, Ltd. TMMP: trimethylolpropane tris(3-mercaptopropionate) manufactured by SC Organic Chemical Co., Ltd. PEMP: pentaerythritol tetrakis(3-mercaptopropionate) manufactured by SC Organic Chemical Co., Ltd. TEMPIC: tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate manufactured by SC Organic Chemical Co., Ltd. β-CEA: β-carboxyethyl acrylate manufactured by Daicel Allnex Corporation Omnirad TPO: IGM Resins B.V. 2,4,6-trimethylbenzoyl-diphenylphosphine oxide manufactured by TCI Pyrogallol: Pyrogallol AA-1.5 manufactured by TCI Advanced Alumina AA-1.5 manufactured by Sumitomo Chemical Co., Ltd.

[0185] [Calculation Method and Evaluation Method] <Thiol / Carbon-Carbon Double Bond> The thiol / carbon-carbon double bond was calculated from the charge ratio of the quantum dot-containing curable composition.

[0186] <Thiol group reaction rate> For each of Examples 1 to 15 and Comparative Examples 1 to 6, the surface of the quantum dot-containing curable composition and the surface of the cured product from which the second base film in each wavelength conversion member was peeled off were measured using an FT-IR NICOLET 6700 (manufactured by Thermo Fisher Scientific). The background measurement was performed in air, with an accumulated number of 32 measurements at 400 cm. －１ ~4000cm －１ A: Peak attributable to S-H stretching vibration in the curable composition or cured product (peak wavelength: 2569 cm －１ ) peak area, B: peak area attributable to C—H stretching vibration in the curable composition or cured product (peak wavelength: 2957 cm －１ The ratio A / B of the peak area of ​​the compound (A / B) was used to calculate the thiol group-derived peak intensity, and the thiol group reaction rate was calculated using the following formula: Thiol group reaction rate [%] = 100 - 100 × [A / B of cured product] / [A / B of curable composition]

[0187] <ESR Intensity> Ten measurement samples measuring 5 mm x 35 mm were cut out from the wavelength conversion layer obtained by peeling off the two substrate films from the wavelength conversion member. The ten measurement samples were placed in a measurement container and measured using an X-band ESR measurement device (EMX manufactured by Bruker) with a microwave of 1.0 mW and a magnetic modulation amplitude of 5.0 Gauss. The measurement temperature was room temperature (25°C). The absolute value of the difference between the maximum and minimum values ​​of the peak between 3400 and 3430 Gauss (corresponding to a g-value of 2.000) was normalized by the sample mass placed in the measurement container to calculate the spin concentration [spins / g].

[0188] <Tg of Wavelength Conversion Layer> A measurement sample measuring 5 mm x 50 mm was cut out from the wavelength conversion layer obtained by peeling off the two base films from the wavelength conversion member. This measurement sample was conditioned for 2 hours or more under an environment of 25°C and 60% relative humidity, and then the dynamic viscoelasticity was measured using a dynamic viscoelasticity measuring device (Vibron: DVA-225 (manufactured by IT Measurement & Control Co., Ltd.)) at a grip distance of 20 mm, a heating rate of 5°C / min, a measurement temperature range of -20°C to 200°C, and a frequency of 1 Hz. Then, line 1 was drawn in the solid region, line 2 was drawn in the glass transition region, and the glass transition temperature Tg was determined by plotting the intersection of lines 1 and 2. As is well known, the solid region can be identified by observing a sudden decrease in storage modulus. The glass transition temperature Tg thus determined was used as the glass transition temperature Tg of the wavelength conversion layer. Furthermore, this Tg was used as the glass transition temperature Tg of the wavelength conversion layer before ultraviolet irradiation in the calculation of ΔTg described below.

[0189] <ΔTg of wavelength converting layer> 1600 mJ / cm from the first base film side of the wavelength converting member ２ The wavelength conversion layer was then irradiated with ultraviolet light using an air-cooled metal halide lamp (manufactured by Eye Graphics) at an exposure dose of 1000 kJ / cm². After ultraviolet irradiation, the two substrate films were peeled off from the wavelength conversion member, and a measurement sample measuring 5 mm x 50 mm was cut out from the wavelength conversion layer. The glass transition temperature Tg (after ultraviolet irradiation) of this measurement sample was measured by the method described above. ΔTg was calculated from the glass transition temperature Tg after ultraviolet irradiation and the glass transition temperature Tg of the wavelength conversion layer before ultraviolet irradiation determined above. For the examples (Examples 1 to 4, Examples 6 to 15) and Comparative Examples 1 to 6 other than Example 5, in which ΔTg was 0°C, the Tg values ​​after ultraviolet irradiation were higher than the values ​​before ultraviolet irradiation.

[0190] <Number of Non-luminescent Defects> Each of the wavelength conversion members of Examples 1 to 15 and Comparative Examples 1 to 6 was cut into a size of 31 cm x 36 cm (equivalent to a 14-inch monitor) and left to stand for 24 hours under an oxygen concentration of 95% by volume, at a room temperature of 25°C, and a pressure of 5 atm (hereinafter also referred to as "oxygen pressurized storage"). After standing, the member was irradiated with ultraviolet light, and the total number of black dot-like non-luminescent defects was counted visually, and the number per unit area was calculated. The oxygen pressurized storage can be considered an accelerated test equivalent to long-term use.

[0191] <Brightness> A commercially available tablet terminal (Kindle (registered trademark) Fire HDX 7 manufactured by Amazon Inc.) equipped with a blue light source in the backlight unit was disassembled, and the backlight unit was removed. The wavelength conversion film QDEF (Quantum Dot Enhancement Film) incorporated in the backlight unit was replaced with a rectangular wavelength conversion member of the Example or Comparative Example. A liquid crystal display device was thus produced. The produced liquid crystal display device was turned on so that the entire screen displayed white, and the brightness was measured using a luminance meter (SR-UL2 manufactured by TOPCON Corporation) placed at a position 520 mm perpendicular to the surface of the light guide plate. For each of the Example and Comparative Example, the brightness (relative brightness) was calculated as a relative value to the brightness of Example 1. Based on the relative brightness thus calculated, brightness was evaluated according to the following evaluation criteria: A: Relative brightness ≧ 98% B: 95% ≦ Relative brightness < 98% C: Relative brightness < 95%

[0192] The results are shown in Table 2.

[0193]

[0194] From the results shown in Table 2, it can be confirmed that in Examples 1 to 15, both high-luminance light emission and suppression of the occurrence of non-light-emitting defects were achieved.

[0195] One aspect of the present invention is useful in the technical field of liquid crystal display devices.

[0196] REFERENCE SIGNS LIST 10, 10A, 10B Wavelength conversion member 12 First base film 12a, 14a Support 12b, 14b Barrier layer 14 Second base film 16 Wavelength conversion layer 18 Resin layer 18a Recess 20 Quantum dot-containing portion 24, 24e Quantum dot 26 Matrix 28 Mixed layer 30 Opaque layer 34 Undercoat organic layer 36 Barrier layer 38 Protective organic layer 50 Backlight unit 52A Light source 52B Light guide plate 52C Planar light source 54 Wavelength conversion member 56A Reflector 56B Retroreflective member 60 Liquid crystal display device 62 Liquid crystal cell unit 64 Liquid crystal cell 68, 70 Polarizing plate 72, 74 Polarizer 76, 78, 82, 84 Polarizing plate protective film L1 Resin layer-forming composition L2 Quantum dot-containing curable composition L3 Coating liquid containing oxygen-impermeable material M Mold

Claims

1. A wavelength converting member having a wavelength converting layer between two substrates, each of the two substrates including a barrier layer and a support, and the barrier layer being located between the support and the wavelength converting layer, the wavelength converting layer including a cured product of a curable composition including quantum dots, a polyfunctional (meth)acrylate, and a polyfunctional thiol, the ratio of the total number of thiol groups to the total number of carbon-carbon double bonds in the curable composition, i.e., total number of thiol groups / total number of carbon-carbon double bonds, being 0.100 or more and 1.800 or less, the reaction rate of the thiol groups of the polyfunctional thiol in the cured product being 66% or more and 100% or less, the glass transition temperature Tg of the wavelength converting layer determined by dynamic viscoelasticity measurement being 3°C or more and 120°C or less, and 1600 mJ / cm ２ a change ΔTg in glass transition temperature of the wavelength conversion layer determined by dynamic viscoelasticity measurement before and after ultraviolet irradiation at an irradiation dose of 10° C. or less.

2. The g=2,000 peak concentration of the wavelength conversion layer measured by electron spin resonance is 4.0×10 ４ Spin / g or more 2.0 x 10 ６ The wavelength conversion member according to claim 1 , having a spin / g or less.

3. The wavelength conversion member according to claim 1, wherein the ΔTg is 5° C. or less.

4. The wavelength conversion member according to claim 2, wherein the ΔTg is 5° C. or less.

5. The wavelength conversion member according to claim 1, wherein each of the two substrates further comprises an organic layer located between the barrier layer and the wavelength conversion layer.

6. The wavelength conversion member according to claim 1, wherein each of the two substrates further includes an organic layer between the barrier layer and the support.

7. The wavelength conversion member according to claim 1, wherein the wavelength conversion layer has a resin layer region having a plurality of recesses, and the recesses contain the cured material.

8. The g=2,000 peak concentration of the wavelength conversion layer measured by an electron spin resonance method is 4.0×10 ４ Spin / g or more 2.0 x 10 ６ 2. The wavelength conversion member of claim 1, wherein the wavelength conversion coefficient is 1 / 2 spins / g or less, the ΔTg is 5°C or less, each of the two substrates further comprises an organic layer located between the barrier layer and the wavelength conversion layer, and an organic layer located between the barrier layer and the support, and the wavelength conversion layer has a resin layer region having a plurality of recesses, and the recesses contain the cured product.

9. A light emitting device comprising the wavelength conversion member according to any one of claims 1 to 8 and a light source.

10. A liquid crystal display device comprising the light emitting device according to claim 9 and a liquid crystal cell.

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