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. The glass transition temperature Tg of the wavelength conversion layer is 5°C or higher. In the four corners of the wavelength conversion member, the number of corners where floating having a length of 200 μm or more is observed is zero to two.

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] Liquid crystal display devices are becoming more and more popular as they consume less power and require less space. Liquid crystal display devices are generally composed of at least a light-emitting device and a liquid crystal cell.

[0003] In recent years, liquid crystal display devices that include a wavelength conversion member in a light emitting device have been attracting attention (see, for example, Patent Document 1).

[0004] WO2019 / 186734

[0005] In a light-emitting device equipped with a wavelength conversion member, when light from a light source is incident on the wavelength conversion member, the phosphor contained in the wavelength conversion member is excited by the incident light and emits fluorescence. By using phosphors with different emission characteristics, it is possible to emit red, green, and blue emission line light from the wavelength conversion member as the fluorescence emitted by the phosphor and / or light emitted from the light source and passed through the wavelength conversion member. This makes it possible to realize white light.

[0006] However, according to the inventor's investigations, it has become clear that in a liquid crystal display device having a light-emitting device equipped with a wavelength conversion member, a decrease in brightness at the edges over time (hereinafter referred to as "decrease in edge brightness over time") may occur.

[0007] An object of one aspect of the present invention is to provide a wavelength conversion member that can contribute to suppressing deterioration in edge luminance over time in a liquid crystal display device.

[0008] One aspect of the present invention is as follows: [1] A wavelength conversion member having a wavelength conversion layer between two substrates, wherein the glass transition temperature Tg of the wavelength conversion layer is 5°C or higher, and the number of corners at which lifts of 200 μm or more are observed (hereinafter also referred to as "lift number") among the four corners of the wavelength conversion member is 0 to 2. [2] The wavelength conversion member according to [1], wherein the amount of deformation in the thickness direction of one or both of the two substrates (hereinafter also referred to as "substrate deformation amount") is 15% or less of the substrate thickness. [3] The wavelength conversion member according to [1] or [2], wherein the distance between the outermost end and the innermost end at the end face of the wavelength conversion member (hereinafter also simply referred to as "distance between the outermost end and the innermost end") is 200 μm or less. [4] The wavelength conversion member according to any of [1] to [3], wherein each of the two substrates includes a barrier layer and a support, and wherein the barrier layer is located between the support and the wavelength conversion layer. [5] The wavelength conversion member according to [4], wherein each of the two substrates further comprises an organic layer between the barrier layer and the wavelength conversion layer. [6] The wavelength conversion member according to [4] or [5], wherein each of the two substrates further comprises an organic layer located between the barrier layer and the support. [7] The wavelength conversion member according to any one of [1] to [6], wherein the peel force between the wavelength conversion layer and the adjacent layer is 0.6 N / cm or more. [8] The elastic modulus of the wavelength conversion layer is 1.0 × 10 ７ Pa or more 1.0×10 １０the wavelength conversion layer further comprises a (meth)acrylic resin.

[11] The wavelength conversion member according to any one of [1] to [7], wherein the elastic modulus of the wavelength conversion layer is 1.0×10 Pa or less. [9] The wavelength conversion member according to any one of [1] to [8], wherein the wavelength conversion layer contains quantum dots.

[10] The wavelength conversion member according to [9], wherein the wavelength conversion layer further comprises a (meth)acrylic resin.

[11] The amount of deformation in the thickness direction of one or both of the two substrates is 15% or less of the substrate thickness, the distance between the outermost end and the innermost end of the end face of the wavelength conversion member is 200 μm or less, 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, and the wavelength conversion layer further includes an organic layer located between the barrier layer and the wavelength conversion layer, and the organic layer further includes an organic layer between the barrier layer and the support, the peel force between the wavelength conversion layer and an adjacent layer is 0.6 N / cm or more, and the wavelength conversion layer has an elastic modulus of 1.0×10 ７ Pa or more 1.0×10 １０

[10] The wavelength conversion member according to [1], wherein the wavelength conversion layer contains quantum dots and a (meth)acrylic resin.

[11] A light emitting device comprising the wavelength conversion member according to any one of [1] to

[10] and a light source.

[12] A liquid crystal display device comprising the light emitting device according to

[10] 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 suppressing deterioration in end luminance over time in a liquid crystal display device. 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] FIG. 4 is a cross-sectional view showing an example of a wavelength conversion member. FIG. 5 is a perspective view conceptually showing an example of a wavelength conversion member. FIG. 6 is a plan view of the wavelength conversion member of FIG. 2. FIG. 7 is a cross-sectional view taken along line III-III of FIG. 2 and FIG. 3. FIG. 8 is a cross-sectional view for explaining an example of the shape of a resin layer of a wavelength conversion member. FIG. 9 is a partially enlarged view of FIG. 4. FIG. 10 is a plan view showing an example of a pattern of a quantum dot-containing region. FIG. 11 is a plan view showing another example of a pattern of a quantum dot-containing region. FIG. 12 is a conceptual view for explaining a method of specifying the outline of a quantum dot-containing region. FIG. 13 is a conceptual view for explaining an example of a method for manufacturing a wavelength conversion member. FIG. 14 is a diagram conceptually showing the configuration of an example of a backlight unit. FIG. 15 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] [Wavelength conversion member] One aspect of the present invention relates to a wavelength conversion member having a wavelength conversion layer between two substrates, wherein the glass transition temperature Tg of the wavelength conversion layer is 5°C or higher, and the number of corners at which lifts of 200 µm or more in length are observed (lift count) is 0 to 2, both inclusive, at four corners of the wavelength conversion member.

[0013] In the present invention and this specification, the term "wavelength conversion layer" refers to a layer in which, when light from a light source is incident on a wavelength conversion member, a phosphor contained in this layer is excited by the incident light and emits fluorescence. The phosphor can be, for example, quantum dots. Quantum dots will be described in detail below.

[0014] The inventors of the present invention believe that the wavelength conversion layer having a glass transition temperature Tg of 5°C or higher and the number of floating portions of 0 to 2 inclusive in the wavelength conversion member can contribute to suppressing deterioration in end luminance over time in a liquid crystal display device. The details are as follows. The deterioration in end luminance over time in a liquid crystal display device is thought to occur due to oxygen intrusion into the wavelength conversion layer, which reduces the luminous performance of the phosphor. Regarding oxygen intrusion into the wavelength conversion layer, it is thought that a wavelength conversion layer with a low glass transition temperature Tg has high fluidity, resulting in a rapid oxygen intrusion rate. In contrast, the inventors of the present invention believe that the slow oxygen intrusion rate in a wavelength conversion layer with a glass transition temperature Tg of 5°C or higher can contribute to suppressing deterioration in the luminous performance of the phosphor due to oxygen. Furthermore, the greater the number of floating portions in the wavelength conversion member, the more easily oxygen can penetrate into the interface between the wavelength conversion layer and the adjacent layer, resulting in more oxygen intrusion into the wavelength conversion layer. In contrast, a wavelength conversion member having a small number of floating portions of 0 to 2 inclusive can contribute to suppressing oxygen intrusion into the wavelength conversion layer. The present inventors believe that this can also contribute to suppressing the deterioration of the luminescence performance of the phosphor due to oxygen. However, the present invention is not limited to the speculations described in this specification.

[0015] The wavelength conversion member will be described in more detail below.

[0016] <Number of Floats> The wavelength conversion member has a rectangular shape in plan view, and the number of four corners of the rectangle where floats having a length of 200 μm or more are observed (the number of floats) is 0 to 2. From the viewpoint of suppressing oxygen penetration into the wavelength conversion layer as described above, the number of floats is 2 or less, preferably 1 or less, and most preferably 0. A means for controlling the number of floats will be described later.

[0017] The number of floating portions is determined by the following method. A test piece having a size of 10 mm x 10 mm and a square shape in plan view, including each of the four corners, is cut out from a wavelength conversion member having a rectangular shape in plan view. The shape of the four corners of the rectangle is not limited to a square shape, but can also be a concave or recessed shape. For a concave or convex corner, the intersection of the extension lines of the two sides extending from that corner is considered to be the vertex of the corner. Of the four side surfaces of each test piece, the two exposed by cutting out the test piece, the remaining two, are the surfaces that were exposed as side surfaces in the wavelength conversion member before being cut out as the test piece. These two side surfaces are observed using an optical microscope. One of the two substrates sandwiching the wavelength conversion layer is called the first substrate, and the other is called the second substrate. It is confirmed whether there is a gap between the first substrate and the wavelength conversion layer and / or between the second substrate and the wavelength conversion layer. For test pieces in which voids were found in only one or both of the above, the range of voids was measured in the direction of the square sides of the test piece (specifically, in the direction of each of the two sides extending from the vertex of the corner) from the vertex of the corner that was the corner of the wavelength conversion member when viewed in a plane. If the measured length in only one or both of the two side directions is 200 μm or more, the test piece was determined to be a test piece in which a lift of 200 μm or more was observed. For example, if two of four test pieces were determined to be test pieces in which a lift of 200 μm or more was observed, the wavelength conversion member being evaluated was a wavelength conversion member in which the number of corners in which a lift of 200 μm or more was observed was "2" among the four corners of the wavelength conversion member.

[0018] <Glass transition temperature Tg of wavelength conversion layer> For the reasons described above, the glass transition temperature Tg of the wavelength conversion layer of the wavelength conversion member is 5°C or higher, preferably 8°C or higher, and more preferably 10°C or higher. The glass transition temperature Tg of the wavelength conversion layer can be, for example, 50°C or lower, 45°C or lower, 40°C or lower, or 35°C or lower. However, a high glass transition temperature Tg of the wavelength conversion layer is preferable from the viewpoint of slowing the oxygen penetration rate, as described above. Therefore, the glass transition temperature Tg of the wavelength conversion layer may exceed the range exemplified here. Means for controlling the glass transition temperature Tg of the wavelength conversion layer will be described later.

[0019] The glass transition temperature Tg of the wavelength conversion layer is determined by the following method. The storage modulus (E') and loss modulus (E'') of a test piece cut out from the wavelength conversion layer of the wavelength conversion member are measured using a dynamic viscoelasticity measuring device. The test piece is cut to a dimension of 10 mm width x 40 mm length. The measurement conditions are "tensile mode, chuck distance: 25 mm, frequency: 10 Hz, measurement temperature range: -20°C to 100°C, heating rate: 5°C / min." As the dynamic viscoelasticity measuring device, for example, a wide-range dynamic viscoelasticity measuring device (Solid Analyzer RSA-III manufactured by Rheometric Scientific) can be used. The loss tangent (tan δ) is determined as the value obtained by dividing the loss modulus (E'') by the storage modulus (E') (loss modulus (E'') / storage modulus (E')). The glass transition temperature Tg is determined as the temperature at the peak top of the loss tangent (tan δ).

[0020] The inventors believe that the number of lifts is affected by the cutting conditions for cutting the wavelength conversion member into a desired shape, such as a product shape, and the elastic modulus of the wavelength conversion layer. More details are provided below. Generally, the rigidity of the wavelength conversion layer tends to be lower than that of the substrate (the support, described in detail below). Therefore, it is presumed that the wavelength conversion layer, after being deformed during cutting, is unlikely to return to its original shape even after cutting is completed. Therefore, it is presumed that significant deformation of the wavelength conversion layer during cutting can cause lifts. Therefore, the cutting conditions can affect the number of lifts. As an example, die cutting can be used to cut the wavelength conversion member into a desired shape. In die cutting, a blank is cut using a punching machine using a die. A die generally known as a Thomson blade can be used as the die. Using a Thomson blade with a sharp cutting angle can contribute to suppressing lifts. Furthermore, the stronger the Thomson blade is pressed into the blank, the more likely lifts tend to occur. Therefore, the blade angle of the Thomson blade used in die cutting and the force with which the Thomson blade is pressed into the raw roll can affect the number of liftings. Furthermore, for example, when a wavelength conversion member is cut out from a raw roll by die cutting under similar cutting conditions, the higher the elastic modulus of the wavelength conversion layer, the more likely it is that lifting will occur. This is presumably because a high elastic modulus of the wavelength conversion layer makes it difficult to cut, resulting in significant deformation of the wavelength conversion layer during cutting. Therefore, the elastic modulus of the wavelength conversion layer can also affect the number of liftings. By producing a wavelength conversion member taking the above points into consideration, a wavelength conversion member with a lifting number of 0 to 2 can be obtained.

[0021] <Substrate Deformation Amount> Regarding the number of lifts, according to the study by the present inventors, wavelength conversion members in which the substrate deformation amount, determined by the method described below, is 15% or less of the substrate thickness in one or both of the two substrates tend to have a lower number of lifts. Furthermore, wavelength conversion members in which the substrate deformation amount is 15% or less of the substrate thickness in both of the two substrates tend to have a lower number of lifts. This is presumably because, in wavelength conversion members with a large substrate deformation amount, the wavelength conversion layer deformed during cutting and then did not easily return to its original shape even after cutting was completed, causing the substrate to deform following the deformation of the wavelength conversion layer. The substrate deformation amount is preferably 10% or less, more preferably 5% or less. The substrate deformation amount can be, for example, 0%, 0% or more, more than 0%, or 1% or more. The substrate deformation amounts of the two substrates may be the same or different. The substrate whose substrate deformation amount is within the above-described range is either one or both of the two substrates, and preferably both. The amount of deformation of the substrate tends to increase as the Thomson blade is pressed deeper into the raw material during die cutting, for example. Therefore, the amount of deformation of the substrate can be reduced by controlling the depth to which the Thomson blade is pressed into the raw material during die cutting.

[0022] The substrate deformation amount is determined by the following method. Five thin slice samples are cut out at 100 μm intervals from a wavelength conversion member having a rectangular shape in plan view along one end face randomly selected from the four end faces (i.e., the four side faces of the wavelength conversion member). Both corners of each thin slice sample include portions of the one end face and the two adjacent end faces. The thin slice sample is cut along its cross section with a microtome to obtain a slice sample including one of the two corners (randomly selected) included in the thin slice sample. Therefore, this slice sample includes portions of the one end face and one of the two adjacent end faces (hereinafter referred to as the "adjacent end face"). From the five thin slice samples, slice samples including corners on the same side are prepared. The cut cross section of each of the five slice samples thus prepared is observed using a scanning electron microscope (SEM). The position of the wavelength conversion layer side surface of the substrate to be observed within a range of 1000 μm to 2000 μm inside from the adjacent end face is defined as a reference position, and the distance in the thickness direction between the position of the end of the substrate to be observed at the adjacent end face and the reference position is defined as the deformation amount in the thickness direction of the substrate (substrate deformation amount). The substrate deformation rate is calculated as "substrate deformation amount / substrate thickness x 100". The method for measuring the substrate thickness will be described later. The arithmetic average of the substrate deformation rates thus calculated for the five slice samples is defined as the substrate deformation rate of the substrate to be evaluated. A substrate deformation rate of 15% or less calculated in this way means that the substrate deformation amount is 15% or less of the substrate thickness.

[0023] <Distance between the outermost end and the innermost end> ​​Regarding the number of lifts, the inventors' studies have confirmed that wavelength conversion members in which the distance between the outermost end and the innermost end on the end face of the wavelength conversion member, as determined by the method described below, is 200 μm or less tend to have a lower number of lifts. In this regard, it is presumed that wavelength conversion members in which the distance is large undergo significant deformation of the wavelength conversion layer during cutting, and this large deformation may be the cause of lifts. The distance is preferably 100 μm or less, more preferably 50 μm or less. The amount of deformation may be, for example, 0 μm, 0 μm or more, more than 0 μm, 1 μm or more, 5 μm or more, or 10 μm or more.

[0024] The distance is determined by the following method. The cut cross sections of the five slice samples used to measure the substrate deformation are observed with an SEM, and the distance between the outermost and innermost ends in the width direction of the adjacent end faces is measured, with the outermost end being the location located furthest outward in the width direction and the innermost end being the location located furthest in the width direction. The arithmetic mean of the distances determined for the five slice samples is taken as the distance between the outermost and innermost ends of the end face of the wavelength conversion member to be evaluated.

[0025] The wavelength converting layer of the wavelength converting member will be described in more detail below.

[0026] <Wavelength Conversion Layer> (Quantum Dots) The phosphor contained in the wavelength conversion layer can be, for example, quantum dots.

[0027] The wavelength conversion layer 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 (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).

[0028] In the present invention and this specification, 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. Furthermore, the "half width" of a peak refers to the width of the peak at half the peak height.

[0029] 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.

[0030] In the wavelength conversion layer, the content of the quantum dots can be, for example, in the range of 0.1 to 10.0% by mass relative to the mass of the wavelength conversion layer (i.e., the mass of the wavelength conversion layer is taken as 100% by mass). When two or more types of quantum dots are contained, the content refers to the total content of these quantum dots. This also applies to the contents and amounts of various components in the present invention and this specification. Furthermore, as described below, when a wavelength conversion layer is formed using a polymerizable composition, the content of the quantum dots in the polymerizable composition can be, for example, in the range of 0.1 to 10.0% by mass relative to the total amount of the composition. In the present invention and this specification, with respect to the polymerizable composition, when the polymerizable composition contains a solvent, the content of each component relative to the total amount of the composition refers to the content calculated assuming that the total content of all components excluding the solvent is 100% by mass. When the polymerizable composition does not contain a solvent, the content of each component relative to the total amount of the composition refers to the content calculated assuming that the total content of all components contained in the composition is 100% by mass.

[0031] The wavelength conversion layer may be a layer containing quantum dots in a matrix, or may be a layer in which the quantum dots are dispersed in the matrix. The matrix may contain a resin, and the resin may be a polymer of one or more polymerizable compounds. Specifically, the wavelength conversion layer may be a layer containing a cured product obtained by curing a polymerizable composition containing one or more quantum dots and one or more polymerizable compounds. In the present invention and this specification, a "polymerizable composition" refers to a composition containing at least one polymerizable compound and having the property of being cured by polymerization treatment such as light irradiation or heating. A "polymerizable compound" refers to a compound containing one or more polymerizable functional groups in one molecule. A "polymerizable functional group" refers to a group that can participate in a polymerization reaction. For example, the "(meth)acryloyl group" and "alicyclic epoxy group" described below are polymerizable functional groups.

[0032] In one embodiment, the wavelength conversion layer may include quantum dots and a (meth)acrylic resin. In the present invention and this specification, the term "(meth)acrylic resin" refers to a polymer of (meth)acrylate. Polymers include homopolymers and copolymers. 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 one 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. Regarding a (meth)acrylate, "monofunctional" refers to a compound containing one (meth)acryloyl group in one molecule, and "polyfunctional" refers to a compound containing two or more (meth)acryloyl groups in one molecule. Furthermore, the (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 indicate either or both of an acryloyloxy group and a methacryloyloxy group.

[0033] The wavelength conversion layer containing quantum dots and a (meth)acrylic resin can be a layer containing a cured product obtained by curing a polymerizable composition containing one or more quantum dots and one or more (meth)acrylates. Various components that can be contained in the polymerizable composition are described below.

[0034] ((Meth)acrylate) The polymerizable composition may contain one or more (meth)acrylates selected from the group consisting of polyfunctional (meth)acrylates and monofunctional (meth)acrylates, and preferably contains at least one polyfunctional (meth)acrylate.

[0035] The polyfunctional (meth)acrylate is one or more types of difunctional or higher functional (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, 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 polymerizable composition may be, for example, not less than 200. From the viewpoint of the viscosity of the polymerizable 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 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 the 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 gel Multipore HXL-M (manufactured by Tosoh Corporation, 7.8 mm ID (Inner Diameter) x 30.0 cm)

[0040] In the polymerizable composition, the content of the polyfunctional (meth)acrylate is preferably 10.0% by mass or more, more preferably 20.0% by mass or more, and even more preferably 30.0% by mass or more, based on the total amount of the composition, from the viewpoint of improving durability. The content of the polyfunctional (meth)acrylate in the polymerizable composition may be, for example, 90.0% by mass or less or 80.0% by mass or less, based on the total amount of the composition. The polymerizable composition may contain only one type of polyfunctional (meth)acrylate, or may contain two or more types.

[0041] (Polyfunctional Thiol) The polymerizable composition may also contain a polyfunctional thiol. The polyfunctional thiol is a difunctional or higher thiol, and preferably a trifunctional or higher thiol. The polyfunctional thiol may be, for example, an octafunctional or lower, heptafunctional or lower, hexafunctional or lower, pentafunctional or lower, or tetrafunctional or lower. From the viewpoint of improving the durability of a wavelength conversion member containing a cured product obtained by curing the polymerizable 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.

[0042] 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 Thioglycolate, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolethane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptoisobutyrate), pentaerythritol tetrakis(2-mercaptoisobutyrate), dipentaerythritol hexakis(3-mercaptopropionate), Examples of the polyfunctional thiol include 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.Examples of commercially available products include commercially available polyfunctional thiols such as Multiol Y3 (trade name) manufactured by SC Organic Chemicals, Inc., which are described in the Examples below.

[0043] The molecular weight of the polyfunctional thiol contained in the polymerizable composition can be, for example, 200 or more, and from the viewpoint of further improving durability, it is preferably 300 or more. From the viewpoint of improving brightness, the molecular weight of the polyfunctional thiol is preferably 1000 or less, and more preferably 500 or less.

[0044] In the polymerizable composition, the content of the polyfunctional thiol, relative to the total amount of the composition, 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, from the viewpoint of improving the durability of a wavelength conversion member containing a cured product obtained by curing the polymerizable composition. Furthermore, from the viewpoint of further improving the durability, the content of the polyfunctional thiol, relative to the total amount of the composition, 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, and even more preferably 25.0% by mass or less. The polymerizable composition may contain only one type of polyfunctional thiol, or may contain two or more types. In a polymerizable composition containing one or more polyfunctional (meth)acrylates and one or more polyfunctional thiols, the higher the content of the polyfunctional (meth)acrylate, the higher the glass transition temperature Tg of the wavelength conversion layer formed using the polymerizable composition tends to be.

[0045] (Functional Group-Containing Compound) The polymerizable composition may contain a compound (also referred to as a "functional group-containing compound") having a functional group selected from the group consisting of a carboxy group, a hydroxy group, a phosphate group, and an amino group. In the functional group-containing compound, the carboxy group may be contained in the form of -COOH or in the form of a salt. The salt of the 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) ２The 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 improving brightness, the functional group is preferably a carboxy group, a hydroxy group, or a phosphate group, and more preferably a carboxy group.

[0046] Examples of functional group-containing compounds include various carboxylic acids, such as saturated fatty acids such as acetic acid, propionic acid, and butyric acid, unsaturated fatty acids such as oleic acid and linoleic acid, aromatic carboxylic acids such as benzoic acid, and carboxylic acids having multiple carboxy groups such as oxalic acid and malonic acid.

[0047] Another example of the functional group-containing compound is a monofunctional or higher functional (meth)acrylate having a functional group selected from the group consisting of a carboxyl group, a hydroxyl group, a phosphate group, and an amino group. Hereinafter, such a (meth)acrylate will also be referred to as a "functional group-containing (meth)acrylate."

[0048] The functional group-containing (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 functional group-containing (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.

[0049] The functional group-containing (meth)acrylate is a monofunctional or higher functional (meth)acrylate. From the viewpoint of improving brightness, the functional group-containing (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.

[0050] The molecular weight of the (meth)acrylate contained as the functional group-containing (meth)acrylate may 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 improving brightness, the molecular weight of the (meth)acrylate contained as the functional group-containing (meth)acrylate is preferably 500 or less, more preferably 400 or less, even more preferably 300 or less, and even more preferably 200 or less.

[0051] Specific examples of functional group-containing (meth)acrylates include carboxy group-containing (meth)acrylates such as acrylic acid, β-carboxyethyl acrylate, 2-acryloyloxyethyl succinic acid, and 2-acryloyloxyethylhexahydrophthalic acid; phosphate group-containing (meth)acrylates such as 2-acryloyloxyethyl acid phosphate; and hydroxy group-containing (meth)acrylates such as 2-hydroxyethyl acrylate.

[0052] In the polymerizable composition, the content of the functional group-containing compound is preferably 0.5% by mass or more relative to the total amount of the composition from the viewpoint of improving brightness. Furthermore, the content of the functional group-containing compound is preferably 20.0% by mass or less relative to the total amount of the composition from the viewpoint of improving durability. The polymerizable composition may contain only one type of the functional group-containing compound, or may contain two or more types. When the functional group-containing (meth)acrylate is a polyfunctional (meth)acrylate, the content of the (meth)acrylate is included in the content of the functional group-containing compound.

[0053] (Alicyclic Epoxy Compound) In one embodiment, the wavelength conversion layer can be a layer formed from a polymerizable composition containing an alicyclic epoxy compound. The "alicyclic epoxy compound" is a compound containing one or two alicyclic epoxy groups in one molecule. The "alicyclic epoxy group" refers to a monovalent group having a cyclic structure in which an epoxy ring and a saturated hydrocarbon ring are condensed, and is preferably a monovalent group having a condensed ring of an epoxy ring and a cycloalkane ring. More preferred alicyclic epoxy compounds include those having the following structure in which an epoxy ring and a cyclohexane ring are condensed: Examples of the structure include those having one or more of the above in one molecule. Two or more of the above structures may be contained in one molecule, and preferably one or two are contained in one molecule. The above structure may also have one or more substituents. Examples of the substituent include an alkyl group (e.g., an alkyl group having 1 to 6 carbon atoms), an alkoxy group (e.g., an alkoxy group having 1 to 6 carbon atoms), a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom), a cyano group, a nitro group, an acyl group, and the like. The above structure is preferably unsubstituted.

[0054] The alicyclic epoxy compound may have a polymerizable functional group other than the alicyclic epoxy group. The content of the compound having both the alicyclic epoxy group and a (meth)acryloyl group is included in the content of the alicyclic epoxy compound.

[0055] Commercially available products that can be suitably used as the alicyclic epoxy compound include CELLOXIDE 2000, CELLOXIDE 2021P, CELLOXIDE 3000, CELLOXIDE 8000, CYCLOMER M100, EPOLEAD GT301, and EPOLEAD GT401 manufactured by Daicel Chemical Industries, Ltd., 4-vinylcyclohexene dioxide manufactured by Sigma-Aldrich Corporation, D-limonene oxide manufactured by Nippon Terpene Chemical Co., Ltd., and SANSO CIZER E-PS manufactured by New Japan Chemical Co., Ltd. These can be used alone or in combination of two or more.

[0056] Alicyclic epoxy compounds can also be produced by known synthesis methods. The synthesis method is not limited. Specific examples of synthesis methods include those described in Maruzen KK Publishing, Fourth Edition, Experimental Chemistry Lecture Series 20, Organic Synthesis II, pp. 213-, 1992, Ed. Examples of such synthesis methods include those described in Alfred Hasfner, "The Chemistry of Heterocyclic Compounds - Small Ring Heterocycles Part 3 Oxiranes," John & Wiley and Sons, An Interscience Publication, New York, 1985; Yoshimura, "Adhesion," Vol. 29, No. 12, pp. 32, 1985; Yoshimura, "Adhesion," Vol. 30, No. 5, pp. 42, 1986; Yoshimura, "Adhesion," Vol. 30, No. 7, pp. 42, 1986; JP-A-11-100378; and Japanese Patent No. 2926262.

[0057] (Additives) The wavelength conversion layer and the polymerizable composition may optionally contain one or more additives. Specific examples of additives include polymerization initiators, acid-base generators, photobase generators, polymers, viscosity modifiers, silane coupling agents, surfactants, antioxidants, oxygen gettering agents, polymerization inhibitors, inorganic particles, light-scattering particles, and white pigments. Commercially available additives can be used, or additives prepared by known methods can also be used. For details of specific additives, see, for example, paragraphs 0108 to 0169 of WO 2018 / 186300. The polymerizable 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 can be used as the solvent.

[0058] (Thickness of wavelength conversion layer) The thickness of the wavelength conversion layer can be, for example, 100 μm or less, and from the viewpoint of thinning the wavelength conversion member, it is preferably 90 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and even more preferably 60 μm or less. The thickness of the wavelength conversion layer can be, for example, 20 μm or more or 30 μm or more, and from the viewpoint of thinning the wavelength conversion member, it can also be less than the value exemplified here.

[0059] In the present invention and this specification, the thickness of the wavelength conversion layer, the substrate, the support, etc. is the thickness measured at one randomly selected point by cutting the wavelength conversion member with a microtome and observing the cross section of the cut piece with an SEM.

[0060] (Elastic Modulus of Wavelength Conversion Layer) From the viewpoint of durability of the wavelength conversion layer, the elastic modulus of the wavelength conversion layer is 1.0 × 10 ７ Pa or more, and ８ On the other hand, from the viewpoint of suitability for die cutting and cutting, the elastic modulus of the wavelength conversion layer is preferably 1.0×10 Pa or more. １０ It is preferable that the pressure is 0.05 Pa or less.

[0061] The elastic modulus of the wavelength conversion layer is determined by the following method. The sample to be measured is placed in an environment at a temperature of 25°C and a relative humidity of 60% for at least 1 hour to condition the humidity, and then the elastic modulus is measured in the same environment. One randomly selected surface of the wavelength conversion layer of the wavelength conversion member to be measured is exposed by a known method. The exposed surface of the wavelength conversion layer is measured using a hardness tester under the following conditions to obtain an unloading curve. The elastic modulus is determined from the obtained unloading curve. As the hardness tester, for example, an HM2000 type hardness tester (manufactured by Fisher Instruments, diamond Knoop indenter) can be used. Maximum load: 50 mN Load application time: 10 seconds Creep: 5 seconds Load unloading time: 10 seconds Holding time after unloading: 60 seconds Number of measurements: 10

[0062] (Rigidity of wavelength conversion layer) As described above, the wavelength conversion layer tends to have lower rigidity than the support included in the substrate. An example of the rigidity is a value calculated as "elastic modulus x thickness." The "elastic modulus x thickness" of the wavelength conversion layer can be, for example, in the range of 0.1 GPa μm or more and 150.0 GPa μm or less.

[0063] (Peeling force) In wavelength conversion members having a strong peeling force between the wavelength conversion layer and the adjacent layer, the above-mentioned lifting tends to be less likely to occur.From this point of view, in the wavelength conversion member, the peeling force between the wavelength conversion layer and the adjacent layer is preferably 0.6 N / cm or more, more preferably 1.6 N / cm or more, and even more preferably 2.4 N / cm or more.The peeling force between the wavelength conversion layer and the adjacent layer can be, for example, 8.0 N / cm or less or 6.0 N / cm or less.However, since a strong peeling force is preferable from the viewpoint of suppressing the occurrence of lifting, the peeling force may exceed the above range.

[0064] Regarding the peeling force, providing an organic underlayer, which will be described later, can contribute to increasing the peeling force. Furthermore, when the wavelength conversion layer has a low modulus of elasticity, the peeling force tends to be high.

[0065] The peel force is determined by the following method: A test piece measuring 30 mm wide and 150 mm long is cut out from the wavelength conversion member to be evaluated. A substrate on one randomly selected side of the cut-out test piece is fixed on a glass plate. The substrate on the other side of the test piece fixed on the glass plate is peeled from the wavelength conversion layer in a direction perpendicular to the glass plate and in the length direction of the wavelength conversion member at a speed of 300 mm / min (peel length: 110 mm) using a Tensilon universal material testing machine (manufactured by A&D Corporation), and the force required for peeling is defined as the peel force (unit: N / cm).

[0066] (Method for producing wavelength conversion layer) In one form, the wavelength conversion layer can be a cured product obtained by curing a polymerizable composition containing quantum dots into a film shape. The term "film shape" is used synonymously with "sheet shape." A wavelength conversion layer of this form can be said to be a continuous layer in which the regions containing quantum dots are continuous. In contrast, in the wavelength conversion layer of the form described below, the regions containing quantum dots are present as discontinuous layers.

[0067] For a method for producing a wavelength conversion member having a wavelength conversion layer that is a cured product obtained by curing a polymerizable composition containing quantum dots into a film, see, for example, paragraphs 0127 to 0155 and Figures 2 and 3 of WO 2018 / 016589. Strengthening the conditions of the curing treatment (heating and / or light irradiation) can contribute to increasing the glass transition temperature Tg and elastic modulus of the formed wavelength conversion layer. Strengthening the curing conditions means, for example, increasing the exposure dose in light irradiation or increasing the heating temperature in heating.

[0068] When the curing treatment is performed by light irradiation, the light may be irradiated directly onto the surface of the coating layer of the polymerizable composition containing quantum dots, or onto the surface of a substrate laminated on the coating layer. In one embodiment, from the viewpoint of ease of forming a thin wavelength conversion layer, the wavelength conversion layer can be formed as follows: A coating layer is formed by applying a polymerizable composition containing quantum dots to one of two substrates used to prepare a wavelength conversion member. When this coating layer is subjected to a curing treatment (heating and / or light irradiation), the curing treatment is terminated when the polymerization reaction of the polymerizable composition has partially progressed (hereinafter referred to as "partial curing"). Thereafter, the other substrate is bonded to the partially cured coating layer, and the curing treatment is again performed to further progress the curing treatment.

[0069] Fig. 1 is a cross-sectional view showing an example of a wavelength conversion member having a wavelength conversion layer that is a cured film formed by curing a polymerizable composition containing quantum dots. Wavelength conversion member 10 shown in Fig. 1 has a wavelength conversion layer 3 between two substrates 1 and 2. The first substrate (substrate 1) and the second substrate (substrate 2) each have a support 4, an organic underlayer 5, a barrier layer 6, and a protective organic layer 7. Details of the substrates will be described later.

[0070] In another embodiment, the wavelength conversion layer may have a region containing quantum dots and a resin layer region having a plurality of recesses, and the recesses may contain the region containing quantum dots. Specifically, the resin layer may have a plurality of recesses that are discretely arranged. A specific embodiment of the wavelength conversion layer of this embodiment 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 illustrated embodiments.

[0071] Fig. 2 shows a perspective view of an example of a wavelength conversion member, Fig. 3 shows a plan view of the wavelength conversion member shown in Fig. 2, and Fig. 4 shows cross-sectional views taken along line III-III in Fig. 2 and Fig. 3. 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 substrate side.

[0072] 2 to 4, the wavelength conversion member 10 has a first substrate 12, a second substrate 14, and a wavelength conversion layer 16. To clearly show the configuration of the wavelength conversion member 10, the second substrate 14 is shown by a dashed line in Fig. 2, and is omitted in Fig. 3. The support included in the substrate may be in the form of a film.

[0073] 4, the first substrate 12 includes, for example, a support 12a and a barrier layer 12b. Similarly, the second substrate 14 includes a support 14a and a barrier layer 14b.

[0074] 4 , the wavelength conversion layer 16 includes a resin layer 18 (see FIG. 5 ) having recesses 18 a formed discretely in the plane direction (main surface direction) of the wavelength conversion member 10, and a cured product (hereinafter also referred to as a "quantum dot-containing region") 20 formed by curing the polymerizable composition in the recesses 18 a of the resin layer 18. The quantum dot-containing region 20 includes quantum dots 24 and a matrix 26 formed by a polymerization reaction of the polymerizable compound. That is, the wavelength conversion layer 16 includes a plurality of quantum dot-containing regions 20 each containing quantum dots 24, spaced apart in the plane direction. More specifically, the quantum dot-containing regions 20, which are regions containing quantum dots 24, are spaced apart in the plane direction by walls that form the recesses 18 a of the resin layer 18 and are discretely arranged in the plane direction.

[0075] 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 12, as shown in Figures 2 and 3, multiple quantum dot-containing regions 20 are arranged in isolation without contact with each other in the plane direction of the first substrate 12. In other words, the plane direction of the film is a two-dimensional direction along the film surface (main surface of the film). In the example shown in Figure 2, the quantum dot-containing region 20 is cylindrical and surrounded by the resin layer 18 in the plane direction of the first substrate 12.

[0076] In the wavelength conversion layer 16, the quantum dot-containing regions 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. 3 , no matter where the wavelength conversion member 10 is linearly cut, the quantum dot-containing regions 20 other than the cut region are surrounded by the resin layer 18 and remain sealed in the planar direction. Furthermore, the quantum dot-containing regions 20 that are cut and exposed to the outside air may lose their original function as regions containing quantum dots 24. However, the quantum dot-containing regions 20 at the cut positions, i.e., the quantum dot-containing regions 20 at the end portions in the planar direction, are usually covered by components such as a frame that constitutes a display device, and are therefore 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 regions that are not exposed to the outside air from the outside air.

[0077] In the wavelength conversion layer 16, the first substrate 12 is laminated on the main surface of the bottom of the recess 18a of the resin layer 18 of the wavelength conversion layer 16. That is, the first substrate 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 substrate 12 is laminated with the barrier layer 12b facing the resin layer 18. On the other hand, the second substrate 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 substrate 12. That is, the second substrate 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 substrate 14 is laminated with the barrier layer 14b facing the resin layer 18.

[0078] Depending on the method for forming the resin layer, the wavelength conversion layer may have through holes instead of recesses, with the substrate as the bottom and the quantum dot-containing region filled in the through holes. In this case, one of the two substrates sandwiching the resin layer (i.e., the wavelength conversion layer) is considered to be a first substrate and the other is considered to be a second substrate film. Furthermore, the through holes are considered to be recesses in the resin layer, and the first substrate is considered to be the bottom of the recesses in the resin layer. On the substrate side considered to be the second substrate, the end of the wall of the resin layer 18 is separated from the second substrate, as described below.

[0079] 4 , in the wavelength conversion layer 16, the wall portion forming the recess 18a of the resin layer 18 preferably has an end portion on the second substrate 14 side separated from the second substrate 14. Furthermore, in the wavelength conversion member 10, a quantum dot-containing region is preferably present between the second substrate 14 and the end portion of the wall portion of the resin layer 18 separated from the second substrate 14, the end portion being on the second substrate 14 side. In a wavelength conversion member having a configuration in which a wavelength conversion layer in which the quantum dot-containing region is divided into multiple regions is sealed with two substrates, a gap is provided between the wall portion dividing the quantum dot-containing region into multiple regions and the substrate, and quantum dots are present in this gap as well, thereby increasing the adhesion between the wavelength conversion layer and the substrate.

[0080] In the following description, the second substrate 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 the "top", and the first substrate 12 side, i.e., the bottom side of the recess 18a of the resin layer 18, will be referred to as the "bottom".

[0081] 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 substrate and the portions forming the outer periphery of the resin layer 18 in the surface direction. 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 regions in the surface direction of the wavelength conversion layer 16 and in the regions outside the outermost quantum dot-containing regions in the surface direction.

[0082] In the examples shown in FIGS. 2 to 4 , the quantum dot-containing region (the quantum dot-containing region within 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. 5 , or may have a cross-sectional shape in which the corners on the upper surface of the trapezoid are chamfered into a curved shape, as conceptually shown on the right side of the same. As shown in FIG. 5 , the cross-sectional shape of the wall portion of the resin layer 18 is preferably a shape that gradually widens at least partially from the upper end downward, preferably from the upper end to the lower end. Here, "from the upper end downward" means from the end on the second substrate 14 side toward the first substrate 12 side. In particular, a shape in which the corners of the upper surface on the second substrate side are chamfered, as shown on the right side of FIG. 5 , 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.

[0083] In the wavelength conversion layer 16, the upper ends of the wall portions forming the recesses 18a of the resin layer 18 are separated from the second substrate 14. Furthermore, the quantum dot-containing regions 20 are provided not only in the recesses 18a of the resin layer 18 but also between the upper ends of the wall portions separated from the second substrate 14 and the second substrate 14. In the wavelength conversion member 10 of the illustrated example, as shown in FIG. 4 , the upper ends of all the wall portions are separated from the second substrate 14, and the quantum dot-containing regions 20 are provided between the wall portions and the second substrate 14. This configuration improves the adhesion between the wavelength conversion layer 16 containing quantum dots 24 and the second substrate on the upper side, i.e., the opening side of the recesses 18a of the resin layer 18.

[0084] As described below, in one example of manufacturing a wavelength conversion member, a coating liquid (resin layer-forming composition) that will form the resin layer is filled into a mold (die) having concaves and convexes corresponding to the recesses and walls of the resin layer, a first substrate is laminated so as to cover the coating liquid filled in the mold, the coating liquid that will form the resin layer is cured, and the mold is removed to form a laminate of the first substrate and the resin layer. Next, a polymerizable composition containing quantum dots is filled into the recesses of the resin layer, and a second substrate is laminated on the resin layer so as to seal the polymerizable composition filled in the resin layer. The polymerizable composition is then cured to produce a wavelength conversion member in which a wavelength conversion layer having a resin layer and a quantum dot-containing region is sandwiched between the first substrate and the second substrate.

[0085] The first substrate and the resin layer can be laminated with sufficient adhesion because the resin layer is laminated in a coating liquid state and then the coating liquid is cured. Furthermore, the resin layer and the quantum dot-containing region can be laminated with sufficient adhesion because the polymerizable composition is filled into the recess and then cured. Regarding the wavelength conversion layer and the second substrate, the region of the resin layer corresponding to the recess filled with the quantum dot-containing polymerizable composition is filled with the quantum dot-containing polymerizable composition in a coating liquid state 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 14, and the quantum dot-containing region 20 is present not only in the recess 18a but also between the upper end of the wall portion separated from the second substrate 14 and the second substrate 14, thereby increasing the adhesion between the wavelength conversion layer 16 and the second substrate 14. In the present invention and this specification, the area between the second substrate 14 and the upper end of the wall portion spaced apart from the second substrate 14 includes not only the area directly above the wall portion whose upper end is spaced apart from the second substrate 14, but also the area between the recess 18a (its upper end) adjacent in the surface direction to the wall portion whose upper end is spaced apart from the second substrate 14 and the second substrate 14.

[0086] In the wavelength conversion layer 16, the wall portions of the resin layer 18 spaced apart from the second substrate 14 are not limited to a configuration in which the upper ends of all the wall portions are spaced apart from the second substrate 14 and a quantum dot-containing region is provided therebetween, as shown in Fig. 4. The more wall portions of the resin layer 18 spaced apart from the second substrate 14, the stronger the adhesion between the wavelength conversion layer 16 and the second substrate 14 can be. In consideration of this point, in the wavelength conversion member 10, it is preferable that the upper ends of the wall portions corresponding to an area of ​​30% or more of the display unit area of ​​the display device in which the wavelength conversion member 10 is used are spaced apart from the second substrate 14, and it is more preferable that the upper ends of all the wall portions are spaced apart from the second substrate 14 and the quantum dot-containing region 20 is in contact with the second substrate 14 over the entire surface.

[0087] In the wavelength conversion layer 16, in the wall portion whose upper end is separated from the second substrate, there is no particular limitation on the gap g (shortest distance) between the upper end (top) of the wall portion and the second substrate 14, as long as they are separated (see FIG. 6 ). Here, the gap g between the upper end of the wall portion and the second substrate 14 is preferably 0.01 to 10 μm, more preferably 0.05 to 4 μm, and even more preferably 0.1 to 4 μm. The gap g between the upper end of the wall portion and the second substrate 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). Note that the "wall portion of the wavelength conversion member 10" refers to "a portion other than the recess 18a of the wavelength conversion member 10." The gap g can be determined as the arithmetic mean of measurements taken at 10 randomly selected locations.

[0088] 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 regions (quantum dot-containing regions 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 region from the bottom of the recesses 18a to the second substrate 14 (i.e., "depth h + gap g") to be 1 to 100 μm. The spacing t between adjacent quantum dot-containing regions is preferably 5 to 300 μm.

[0089] 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 region is preferably 1 μm or more. On the other hand, as the quantum dot-containing region becomes thicker, the amount of light absorbed by the quantum dot-containing region increases. Taking these points into consideration, the thickness of the quantum dot-containing region from the bottom of the recess 18a to the second substrate 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 region from the bottom of the recess 18a to the second substrate 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 region can be determined by the arithmetic mean of the measurements of 10 randomly selected quantum dot-containing regions.

[0090] Furthermore, the distance t between adjacent quantum dot-containing regions, i.e., the thickness of the wall of the resin layer 18 between adjacent quantum dot-containing regions (between adjacent recesses 18a), is preferably short (thin walls) to prevent the resin layer 18 from being visible. On the other hand, from the viewpoints of strength and durability, the distance t between adjacent quantum dot-containing regions is preferably a certain value or greater. From these viewpoints, the distance t between adjacent quantum dot-containing regions 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 regions is the shortest distance between adjacent quantum dot-containing regions. 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 regions. Furthermore, the distance t between adjacent quantum dot-containing regions can be calculated by taking the arithmetic mean of the distances at 20 randomly selected locations.

[0091] The shape, size, arrangement pattern, etc. of the quantum dot-containing regions are not particularly limited and may be designed as appropriate. The design may take into consideration geometric constraints for spacing the quantum dot-containing regions 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 regions, 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 shortest distance between adjacent quantum dot-containing regions, i.e., a thick wall thickness, is preferable from the viewpoint of improving the mechanical strength of the wavelength conversion member. The shape, size, arrangement pattern, etc. of the quantum dot-containing regions may be designed taking these points into consideration.

[0092] The ratio of the volume Vp of the quantum dot-containing region to the volume Vb of the resin layer 18 may 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 region 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.

[0093] The wavelength conversion member 10 can have a configuration in which the wavelength conversion layer 16 having such a resin layer 18 and quantum dot-containing region 20 is sandwiched between a first substrate 12 and a second substrate 14 .

[0094] In the wavelength conversion member 10 shown in FIGS. 2 to 4 , the quantum dot-containing region (recess 18 a) is cylindrical and circular in plan view. However, there are no particular limitations on the shape of the quantum dot-containing region. For example, the quantum dot-containing region may be a polygonal prism, such as a square in plan view as shown in FIG. 7 or a hexagonal (honeycomb structure) in plan view as shown in FIG. 8 , or may be a regular polygonal prism. In the above examples, the bottom surface of the cylinder or polygonal prism is arranged parallel to the substrate surface. However, the bottom surface does not necessarily have to be arranged parallel to the substrate surface. Furthermore, the shape of each quantum dot-containing region may be irregular.

[0095] When the boundary between the matrix 26 of the quantum dot-containing region and the resin layer 18 is unclear, as shown in FIG. 9 , 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 region (the boundary between the quantum dot-containing region 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 outline m of the quantum dot-containing region. 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. 9 . In the above-described embodiment, the quantum dot-containing regions are periodically arranged in a pattern. However, a non-periodic arrangement is also acceptable as long as the multiple quantum dot-containing regions are discretely arranged, as long as the desired performance is not impaired. It is preferable that the quantum dot-containing regions are uniformly distributed throughout the entire wavelength conversion layer 16, as this results in a uniform in-plane distribution of brightness.

[0096] In order to obtain a sufficient amount of fluorescence, it is preferable that the area occupied by the quantum dot-containing region is large. The quantum dots 24 in the quantum dot-containing region may be of one type or of multiple types. Furthermore, the quantum dots 24 in one quantum dot-containing region may be of one type, and among the multiple quantum dot-containing regions, 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 number of types of quantum dots may be three or more. Details of quantum dots are as described above.

[0097] As described above, there are no particular limitations on the shape or arrangement pattern of the quantum dot-containing region 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 region at the cut edge may deteriorate. However, because the quantum dots in the portion other than the cut edge are surrounded and sealed by resin along the film surface, performance degradation due to oxygen intrusion along the film surface can be suppressed.

[0098] As described above, the wavelength conversion member 10 shown in FIGS. 2 to 4 has a configuration in which a wavelength conversion layer 16 is laminated on one surface of a first substrate 12, and a second substrate 14 is further laminated on top of the wavelength conversion layer 16, with the wavelength conversion layer 16 being sandwiched between the two substrates.

[0099] The resin layer 18 can be formed, for example, by preparing a resin layer-forming composition containing one or more polymerizable compounds, applying the composition, and curing the composition.

[0100] The desired shortest distance between the quantum dot-containing regions, i.e., the desired distance t between the quantum dot-containing regions (recesses 18 a), varies depending on the composition of the resin layer 18. Note that the shortest distance between adjacent quantum dot-containing regions in the resin layer 18 means the shortest distance within the film plane between adjacent quantum dot-containing regions when observed from the main surface of the wavelength conversion member.

[0101] For the resin layer-forming composition (polymerizable composition), reference can be made to paragraphs 0174 to 0179 of WO2018 / 186300.

[0102] An example of a manufacturing process for the wavelength conversion member will be described with reference to the conceptual diagram of FIG.

[0103] 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 polymerizable composition containing quantum dots is also prepared. Furthermore, a mold M having a concave-convex pattern corresponding to the recesses 18a and wall portions of the resin layer 18, as well as the first substrate 12 and the second substrate 14, are prepared for forming the resin layer 18.

[0104] After preparing these, first, as shown in the first and second rows of Fig. 10, the prepared resin layer-forming composition L1 is filled into the prepared mold M, and as shown in the third row of Fig. 10, the first substrate 12 is laminated on 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. 10, 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 substrate 12 with the bottom of the recess 18a facing the first substrate 12.

[0105] 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 10, and various known methods for forming sheet-like objects with recesses and projections can be used. For example, a method in which a resin layer-forming composition L1 is first applied to the first substrate 12, a mold M is pressed against the resin layer-forming composition L1, and then the resin layer-forming composition L1 is cured is exemplified. A method in which the first substrate 12 and the mold M are laminated together, the resin layer-forming composition L1 is filled between the first substrate 12 and the mold M, and then the resin layer-forming composition L1 is cured is also exemplified. In addition to these methods, a method in which a planar resin layer is formed and then the resin layer 18 having the recesses 18a is formed by etching, or a method in which the resin layer 18 having the recesses 18a is formed using a printing method such as an inkjet method or a dispenser method can also be used.

[0106] <Substrate> The wavelength conversion member has the wavelength conversion layer between two substrates. Only one of the two substrates may contain a barrier layer, or both may contain barrier layers, preferably both. In the present invention and this specification, the term "barrier layer" refers to a layer containing at least one inorganic substance. In a wavelength conversion member, the barrier layer can function as a protective layer for suppressing the intrusion of oxygen and / or water into the wavelength conversion layer. The two substrates may be the same substrate, or may have different layer configurations and / or constituent components. A substrate having a barrier layer preferably includes at least a barrier layer and, from the viewpoint of the durability of the substrate, preferably also includes a support. The stacking order is preferably "support / barrier layer / wavelength conversion layer." Here, " / " is used to mean both direct contact between the left and right portions and the presence of one or more other layers between them. For example, the support and the barrier layer may be in direct contact, or one or more organic layers may be present between the support and the barrier layer. Furthermore, for example, the barrier layer and the wavelength conversion layer may be in direct contact with each other, or one or more organic layers may be present between the barrier layer and the wavelength conversion layer.

[0107] (Barrier Layer) The barrier layer is a layer containing at least one inorganic substance, and is preferably an inorganic layer. In the present invention and this specification, the term "inorganic layer" refers to a layer containing an inorganic substance as a main component. The term "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 having an inorganic substance content of 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 barrier 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.

[0108] 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.

[0109] Among the above inorganic substances, silicon nitride, silicon oxide, and aluminum oxide are preferred. The oxides may have a stoichiometric or non-stoichiometric composition. The same applies to nitrides.

[0110] The method for forming the barrier layer is not particularly limited, and various film-forming methods can be used, for example, by evaporating and / or scattering a film-forming material and depositing it on the surface on which the barrier layer is to be formed. Examples of such methods include a vacuum deposition method in which an inorganic material is heated to deposit the material; an oxidation reaction deposition method in which an inorganic material is used as a raw material and is oxidized by introducing oxygen gas to deposit the material; a sputtering method in which an inorganic material is used as a target raw material and is deposited by sputtering by introducing argon gas and / or oxygen gas; a chemical vapor deposition method in which an inorganic material is heated by a plasma beam generated by a plasma gun to deposit the material; and physical vapor deposition methods such as an ion plating method in which an inorganic material is heated by a plasma beam generated by a plasma gun to deposit the material.

[0111] Thickness of Barrier Layer From the viewpoint of barrier properties, the thickness of the barrier layer is preferably 30 nm or more, and more preferably 50 nm or more. From the viewpoint of thinning the wavelength conversion member, the thickness of the barrier layer is preferably 600 nm or less, more preferably 500 nm or less, even more preferably 400 nm or less, still more preferably 300 nm or less, still more preferably 200 nm or less, and even more preferably 100 nm or less.

[0112] (Support) The substrate support 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 7105:2008, that is, 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.

[0113] Specific examples of the support include polyester films such as polyethylene terephthalate (PET), films made of polymers having a cyclic olefin structure, and polystyrene films.

[0114] Thickness of Support The thickness of the support is preferably in the range of 6 to 75 μm, more preferably in the range of 9 to 50 μm, from the viewpoint of improving the impact resistance of the wavelength conversion member.

[0115] Elastic Modulus of Support The elastic modulus of the support is not particularly limited. From the viewpoint of transportability of the substrate, the elastic modulus of the support is preferably 1.0 GPa or more, more preferably 2.0 GPa or more, and even more preferably 3.0 GPa or more. The elastic modulus of the support can be, for example, 10.0 GPa or less, 8.0 GPa or less, or 6.0 GPa or less. The elastic modulus of the support is determined as the tensile elastic modulus described in item 3.9 of JIS K 7161-1:2014.

[0116] As described above, the support tends to have higher rigidity than the wavelength conversion layer. The rigidity index, "elastic modulus x thickness," for the support can be, for example, in the range of 160.0 GPa μm to 300.0 GPa μm.

[0117] (Organic Layer) The substrate may be composed of only a support and a barrier layer, or may have one or more additional layers. For example, in the wavelength conversion member 10 of the example shown in Fig. 1 , the first substrate 1 and the second substrate 2 each have an underlying organic layer 5 between the support 4 and the barrier layer 6, and a protective organic layer 7 between the barrier layer 6 and the wavelength conversion layer 3. In the wavelength conversion member 10 of the example shown in Fig. 4 , the barrier layer 12b of the first substrate (and the barrier layer 14b of the second substrate 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. 4 .

[0118] In the present invention and this specification, an "organic layer" refers to a layer containing an organic substance as a main component. The organic layer may be a layer having an organic substance content of 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 organic layer may be a layer composed solely of an organic substance. Here, a layer composed solely of an organic substance refers to a layer containing only an organic substance, excluding impurities that are inevitably mixed in during the manufacturing process. The organic layer may contain only one type of organic substance, or two or more types of organic substances.

[0119] The organic base layer 34 on the surface of the support 12a, i.e., the layer below the barrier layer 36, is a base layer (undercoat layer) for properly forming the barrier layer 36. This also applies to the organic base layer 5 in the example shown in FIG.

[0120] 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. It can also be a layer that enhances adhesion between the barrier layer and the wavelength conversion layer. This also applies to the protective organic layer 7 in the example shown in FIG. 1 .

[0121] For the organic layer, see 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 may contain a cardo polymer. This preferably enhances the adhesion between the organic layer and adjacent layers, particularly with inorganic layers. For details about the cardo polymer, see paragraphs 0085 to 0095 of JP-A No. 2005-096108.

[0122] The organic layer can be formed on the surface of the barrier layer, the surface of the support, or the surface of the wavelength converting layer by a known film-forming method using a polymerizable composition. The thickness of the organic layer is preferably in the range of 0.1 to 10 μm.

[0123] The substrate having a barrier layer 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.

[0124] The oxygen permeability of the substrate is 1 cc / (m ２ The oxygen permeability of the substrate 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. It is also preferable that the substrate having a barrier layer has a water vapor barrier property that blocks water vapor.

[0125] When one of the two substrates included in the wavelength conversion member does not have a barrier layer, the above description regarding the substrate can be referred to for such substrate, except that it does not have a barrier layer.

[0126] The cutting for cutting out the wavelength conversion member into a desired shape such as a product shape is as described above.

[0127] [Light-emitting device] One aspect of the present invention relates to a light-emitting device including the wavelength conversion member and a light source.

[0128] 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.

[0129] An example of a backlight unit will be described below with reference to the drawings. Fig. 11 is a schematic diagram showing the general configuration of a backlight unit.

[0130] As shown in FIG. 11, the backlight unit 50 emits primary light (blue light L Ｂ 11 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 in between, 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 each other in the drawing, they may actually be formed in close contact with each other.

[0131] 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 LＢ By irradiating the green light L Ｇ Quantum dots that emit red light L Ｒ The wavelength conversion member is configured by sandwiching a wavelength conversion layer containing quantum dots that emit light between two substrates.

[0132] In FIG. 11, 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.

[0133] 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.

[0134] 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 the emission intensity of the blue light is 25 nm or less.

[0135] The light source 52A can be, for example, a blue light-emitting diode. The blue light-emitting diode can emit blue light having a central emission wavelength in the wavelength band of, for example, 430 to 480 nm. Alternatively, an ultraviolet light-emitting diode that emits ultraviolet light may be used as the light source 52A. In addition to a light-emitting diode, a laser light source or the like can be used as the light source 52A. When a light source that emits ultraviolet light is provided, the wavelength conversion layer 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.

[0136] As shown in Fig. 11, 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.

[0137] <Configuration of Backlight Unit> In Fig. 11, 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.

[0138] 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.

[0139] 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 Nos. 3,416,302, 3,363,565, 4,091,978, 3,448,626, etc.

[0140] [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.

[0141] An example of a liquid crystal display device will be described below with reference to the drawings. Fig. 12 is a schematic diagram showing the general configuration of a liquid crystal display device.

[0142] 12, a liquid crystal display device 60 includes a backlight unit 50 as a light emitting device, and a liquid crystal cell unit 62 disposed opposite the retroreflective member side of the backlight unit. The backlight unit 50 emits white light L Ｗ can be emitted.

[0143] As shown in Figure 12, 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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. "%" in the following descriptions means % by mass.

[0149] [Preparation of Substrate A] <Support> A substrate having an organic underlayer, an inorganic layer, and a protective organic layer formed on one side of a support was prepared as follows: A polyethylene terephthalate (PET) film (Cosmoshine A4360, manufactured by Toyobo Co., Ltd., thickness 50 μm) was used as the support. The elastic modulus of this support was measured in accordance with JIS K 7161-1:2014 and was found to be 4.0 GPa.

[0150] <Formation of Underlayer Organic Layer> Trimethylolpropane triacrylate (TMPTA manufactured by Daicel Allnex Corporation) and a photopolymerization initiator (ESACURE KTO46 manufactured by Lamberti) 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 amount: approximately 600 mJ / cm ２ The coating solution was cured by heating the coated film, and the film was then wound up. The thickness of the formed organic underlayer was 1.0 μm.

[0151] <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 raw material 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 ultimate film thickness was 50 nm.

[0152] <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 conveyed 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 0.5 μm.

[0153] In this way, a substrate A having the layer structure shown in Figure 1 was prepared. The oxygen permeability of the prepared substrate 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 3.5 x 10 －３ cc / (m ２ ・day・atm) or less.

[0154] [Preparation of Substrate B] Substrate B was prepared by the same method as described for substrate A, except that no underlying organic layer was formed.

[0155] [Preparation of Quantum Dot-Containing Polymerizable Compositions A and B] Quantum dot-containing polymerizable compositions A and B were each prepared by mixing the components shown in Table 1. In Table 1, the units are % by mass.

[0156]

[0157] Details of the various components in Table 1 are as follows: Polyfunctional (meth)acrylate: tricyclodecane dimethanol diacrylate (NK Ester A-DCP manufactured by Shin-Nakamura Chemical Co., Ltd.) Polyfunctional thiol: trimethylolpropane tris(3-mercaptopropionate) (TMMP manufactured by SC Organic Chemical Industries, Ltd.) Alicyclic epoxy compound: alicyclic epoxy monomer (Celloxide 2021P manufactured by Daicel Chemical Industries, Ltd.) Photopolymerization initiator: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (IRGACURE TPO manufactured by BASF) Photobase generator: Photobase generator WPBG-266 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Quantum dots: A CdSe / ZnS (core / shell) dispersion (Gen3.5 QD Concentrate manufactured by Nanosys) was used as the quantum dot phosphor IBOA (isobornyl acrylate) dispersion. Isobornyl acrylate was used as the dispersion medium for this CdSe / ZnS (core / shell) dispersion. The CdSe / ZnS (core / shell) dispersion contained 90% or more by mass of isobornyl acrylate. The carboxylic acid was acetic acid manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. The white pigment was titanium oxide (Typure R-706 manufactured by Chemours, particle size 0.36 μm). A first metal oxide layer containing silicon oxide, a second metal oxide layer containing aluminum oxide, and an organic layer containing a polyol compound were provided on the surface of the titanium oxide in this order: the first metal oxide layer, the second metal oxide layer, and the organic layer.

[0158] [Example 1] <Preparation of Wavelength Conversion Member Raw Sheet> The quantum dot-containing polymerizable composition shown in Table 2 was applied to the protective organic layer side of substrate B as a first substrate to form a coating film. Substrate A was then prepared as a second substrate, and laminated so that the protective organic layer was in contact with the wavelength conversion layer. The quantum dot-containing polymerizable composition was then photocured while pressed together with a laminator to produce a wavelength conversion member. The quantum dot-containing polymerizable composition was photocured by irradiating ultraviolet light from the first substrate side with the exposure dose shown in Table 2 using an air-cooled metal halide lamp (manufactured by iGraphics Co., Ltd.). The thickness of the wavelength conversion layer was adjusted to the thickness shown in Table 2 by adjusting the pressure of the laminator.

[0159] <Die Cutting> The wavelength conversion member thus produced was die-cut into a size of 10 cm x 10 cm using a punching device (die cutting). The die-cutting conditions were as follows: a Thomson blade with a blade angle shown in Table 2 was used, and the die-cutting was performed with a pressing amount shown in Table 2. In this way, the wavelength conversion member of Example 1 was obtained. The wavelength conversion member of Example 1 has the layer structure shown in FIG. 1 .

[0160] The push-in amount shown in Table 2 is determined by the following method. A PET film having a thickness of T μm is placed on the punching table of the punching device, and die-cutting is performed while increasing the push-in depth of the Thomson blade. The die-cutting conditions under which the T μm PET film is exactly cut are defined as the die-cutting conditions for the push-in amount T μm. A PET film is placed as an underlay, and the wavelength conversion member raw sheet is placed on the underlay PET film, and the wavelength conversion member raw sheet is die-cut under the die-cutting conditions for the push-in amount T μm. The thickness of the underlay PET film may be any thickness that does not allow the Thomson blade to penetrate during die-cutting.

[0161] Examples 2 to 11, Comparative Examples 1 and 2 A raw sheet of wavelength conversion member was produced and die-cut by the method described for Example 1, except that the items shown in Table 2 were changed as shown in Table 2.

[0162] The method for measuring the thickness and elastic modulus of the wavelength conversion layer shown in Table 2 below will be described later.

[0163]

[0164] [Evaluation Method] A plurality of wavelength conversion members were produced for each of Examples 1 to 11 and Comparative Examples 1 and 2 by the above-described method, and the following evaluations were carried out using each of the plurality of wavelength conversion members, except for the evaluation of peel force described below.

[0165] <Elastic modulus of wavelength conversion layer> The second substrate side of the wavelength conversion member and the glass were bonded using Aron Alpha (registered trademark) (manufactured by Toagosei Co., Ltd.), and then the elastic modulus of the wavelength conversion layer was measured for the surface from which the first substrate was peeled using an HM2000 hardness tester (manufactured by Fisher Instruments, diamond Knoop indenter) by the method described above.

[0166] <Thickness of wavelength conversion layer> The wavelength conversion member was cut with a microtome, and the cross section of the cut piece was observed with an SEM to measure the thickness at one randomly selected point. The thickness of the wavelength conversion layer thus obtained was multiplied by the elastic modulus obtained by the method described above to calculate "elastic modulus × thickness."

[0167] <Glass transition temperature Tg of wavelength conversion layer> The wavelength conversion member from which the first substrate and the second substrate were peeled was cut into a specimen measuring 10 mm in width and 40 mm in length. The glass transition temperature Tg of this specimen was determined by the method described above using a wide-range dynamic viscoelasticity measuring device (Solid Analyzer RSA-III manufactured by Rheometric Scientific).

[0168] <Substrate Deformation Amount and Substrate Deformation Ratio> The substrate deformation amount and substrate deformation ratio of the first substrate and the second substrate in the wavelength conversion member were determined by the methods described above.

[0169] <Distance Between Outermost End and Innermost End on End Face of Wavelength Conversion Member> The distance between the outermost end and innermost end on the end face of the wavelength conversion member was determined by the method described above.

[0170] <Peel Force> A test piece measuring 30 mm wide x 150 mm long was cut out from the raw wavelength conversion member. The second substrate of this test piece was fixed on a glass plate. Thereafter, the peel force was determined by the method described above.

[0171] <Number of Lifts> The number of four corners of the wavelength conversion member where lifts having a length of 200 μm or more were observed (number of lifts) was determined by the method described above.

[0172] <Decrease in Edge Brightness Over Time> The presence or absence of deterioration of the wavelength conversion layer from the end face of the wavelength conversion member was evaluated using the following method. The wavelength conversion member was stored for 800 hours in a high-temperature, high-humidity environment at a temperature of 60°C and a relative humidity of 90%. A commercially available liquid crystal display device (a tablet terminal manufactured by Amazon, product name "Kindle (registered trademark) Fire HDX 7") equipped with a blue light source in the backlight unit was disassembled, and the backlight unit was removed. The wavelength conversion member after storage in the high-temperature, high-humidity environment was incorporated into the backlight unit in place of the wavelength conversion film QDEF (Quantum Dot Enhancement Film). Blue light was irradiated from one substrate side, and the transmitted light was observed from the other substrate side using an optical microscope. The maximum width from the end of the portion of the wavelength conversion member where the wavelength conversion layer had deteriorated and was not emitting light (end non-emission width) was measured. The extent of decrease in edge brightness over time was evaluated from the measured value of the edge non-light-emitting width thus obtained according to the following evaluation criteria: (Evaluation criteria) AAA: Less than 250 μm AA: 250 μm or more and less than 500 μm A: 500 μm or more and less than 1000 μm B: 1000 μm or more and less than 2000 μm C: 2000 μm or more and less than 3000 μm D: 3000 μm or more

[0173] The results are shown in Table 3.

[0174]

[0175] From the results shown in Table 3, it can be confirmed that in the liquid crystal display devices incorporating the wavelength conversion members of Examples 1 to 11, the decrease in edge luminance over time is suppressed.

[0176] One aspect of the present invention is useful in the technical field of liquid crystal display devices.

[0177] REFERENCE SIGNS LIST 1, 2 Substrate 3 Wavelength conversion layer 4 Support 5 Underlying organic layer 6 Barrier layer 7 Protective organic layer 10 Wavelength conversion member 12 First substrate 12a, 14a Support 12b, 14b Barrier layer 14 Second substrate 16 Wavelength conversion layer 18 Resin layer 18a Recess 20 Quantum dot-containing region 24, 24e Quantum dot 26 Matrix 34 Underlying 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 M mold

Claims

1. A wavelength conversion member having a wavelength conversion layer between two substrates, wherein the glass transition temperature Tg of the wavelength conversion layer is 5°C or higher, and the number of corners at which a lift of 200 μm or more in length is observed is between 0 and 2.

2. The wavelength conversion member according to claim 1, wherein the deformation amount in the thickness direction of one or both of the two substrates is 15% or less of the substrate thickness.

3. The wavelength conversion member according to claim 1, wherein the distance between the outermost end and the innermost end of the end face of said wavelength conversion member is 200 μm or less.

4. The wavelength conversion member according to claim 1, wherein 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.

5. The wavelength conversion member according to claim 4, wherein each of the two substrates further includes an organic layer located between the barrier layer and the wavelength conversion layer.

6. The wavelength conversion member according to claim 5, 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 peel strength between the wavelength conversion layer and the adjacent layer is 0.6 N / cm or more.

8. The elastic modulus of the wavelength conversion layer is 1.0×10 ７ Pa or more 1.0×10 １０ The wavelength conversion member according to claim 1 , wherein the viscosity is 100 Pa or less.

9. The wavelength conversion member according to claim 1, wherein the wavelength conversion layer includes quantum dots.

10. The wavelength conversion member according to claim 9, wherein the wavelength conversion layer further contains a (meth)acrylic resin.

11. The amount of deformation in the thickness direction of one or both of the two substrates is 15% or less of the substrate thickness, the distance between the outermost end and the innermost end of the end face of the wavelength conversion member is 200 μm or less, 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, and the wavelength conversion member further includes an organic layer located between the barrier layer and the wavelength conversion layer and further includes an organic layer between the barrier layer and the support, the peel force between the wavelength conversion layer and an adjacent layer is 0.6 N / cm or more, and the wavelength conversion layer has an elastic modulus of 1.0×10 ７ Pa or more 1.0×10 １０ The wavelength conversion member according to claim 1 , wherein the wavelength conversion layer contains quantum dots and a (meth)acrylic resin.

12. A light emitting device comprising the wavelength conversion member according to any one of claims 1 to 11 and a light source.

13. A liquid crystal display device comprising the light emitting device according to claim 12 and a liquid crystal cell.

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