Wavelength conversion sheet, backlight, and liquid crystal display device

Abstract

Provided is a wavelength conversion sheet having excellent adhesion between a phosphor layer and a primer layer even after a long-term environmental test. A wavelength conversion sheet provided with a phosphor layer containing a phosphor and a film for a wavelength conversion sheet provided on at least one surface side of the phosphor layer, the film for a wavelength conversion sheet being obtained by laminating at least a base material layer and a primer layer, the primer layer being in contact with the phosphor layer, the phosphor layer and the primer layer containing an element X, cQD (atomic%) is the average value of the ratio of the element X in the phosphor layer as determined by X-ray photoelectron spectroscopy in a region from the interface between the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer; when the proportion of the element X in the primer layer obtained by X-ray photoelectron spectroscopy at an arbitrary depth in a region from the interface to 20-40 nm (inclusive) in the thickness direction of the primer layer is defined as CPR (atomic%), CPR / CQD is 0.10 or less.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a wavelength conversion sheet, and a backlight and a liquid crystal display device each having the wavelength conversion sheet. BACKGROUND

[0002] With the development of personal computers, the demand for liquid crystal display devices has increased. In addition, the popularity of liquid crystal televisions for home use has also increased in recent years, and furthermore, smart phones and tablet terminals have also become widespread. Therefore, the market for liquid crystal display devices is in a further expanding situation.

[0003] A liquid crystal display device generally has a color filter, a liquid crystal cell, and a backlight. In addition, the liquid crystal display device controls the intensity of light by the shutter function of the liquid crystal layer in the liquid crystal cell, and displays the color of each pixel by the color filter by dividing into three primary colors of R, G, and B, thereby displaying an image.

[0004] As a light source of a backlight of a liquid crystal display device, a cold cathode tube has been used in the past. However, from the viewpoint of low power consumption and space saving, the light source of the backlight is switched from the cold cathode tube to an LED.

[0005] Regarding the LED used as the light source of the backlight, a white LED in which a blue LED and a YAG-based yellow phosphor are combined is widely used. The spectral distribution of the light emitted by the white LED is wide, and is called pseudo white.

[0006] On the other hand, in recent years, development of a backlight using quantum dot technology is also advancing. Quantum dots refer to semiconductor nanoparticles. Quantum dots can adjust the entire visible region of the light emission wavelength by the quantum confinement effect (quantum size effect) in which an electron or an exciton is confined to a small crystal of nanometer size. Quantum dots can produce strong fluorescence in a narrow wavelength band, and therefore a display device can be illuminated with light of three primary colors having excellent color purity. Therefore, by using a backlight of quantum dots, a display device having excellent color reproduction can be formed.

[0007] The wavelength conversion sheet used in the backlight of the display device has a phosphor layer in which semiconductor nanometer-sized phosphor particles are dispersed in a resin layer, a film formed on the surface of the phosphor layer for the purpose of protecting the phosphor layer, and an LED light source combination. The film has water vapor barrier properties for the purpose of suppressing the deterioration of the phosphor layer. For example, Patent Document 1 develops a wavelength conversion sheet in which a barrier film is laminated on a phosphor layer containing a phosphor, and a barrier layer is laminated on one side of a prescribed polyethylene terephthalate film.

[0008] In order to further suppress the intrusion of water vapor into the phosphor layer, for example, as in Patent Documents 2 and 3, attempts have been made to improve the adhesion of the phosphor layer to the barrier film having the barrier layer.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: International Publication No. 2015 / 037733

[0012] Patent Document 2: Japanese Patent Application Publication No. 2020-19141

[0013] Patent Document 3: Japanese Patent Application Publication No. 2020-160212 SUMMARY

[0014] Problems to be Solved by the Invention

[0015] The wavelength conversion sheet of Patent Documents 2 and 3 is configured such that a primer layer on the outermost surface of the barrier film is in contact with the phosphor layer. When the wavelength conversion sheet of Patent Documents 2 and 3 is left for a long time in a high-temperature high-humidity environment of 60°C and 90% RH (hereinafter referred to as "long-term environmental test"), peeling occurs between the phosphor layer and the primer layer. Due to the occurrence of the peeling, oxygen and water vapor intrude into the inside of the wavelength conversion sheet, and a problem of degradation of the phosphor layer occurs.

[0016] The present disclosure was made in view of the above problem, and aims to provide a wavelength conversion sheet in which the adhesion between the phosphor layer and the primer layer is excellent even after a long-term environmental test, and a backlight and a liquid crystal display device each having the wavelength conversion sheet.

[0017] Means for Solving the Problem

[0018] To solve the above problem, the present disclosure provides the following <1> to <14>.

[0019] <1> A wavelength conversion sheet comprising: a phosphor layer containing a phosphor, and a wavelength conversion sheet film provided on at least one surface side of the phosphor layer, the wavelength conversion sheet film being formed by at least laminating a base material layer and a primer layer, the primer layer being in contact with the phosphor layer, the phosphor layer and the primer layer containing an element X, wherein an average value of a proportion of the element X in the phosphor layer obtained by X-ray photoelectron spectroscopy in a region up to 400 nm in a thickness direction of the phosphor layer from an interface between the primer layer and the phosphor layer is set to C QD (atom%), and a proportion of the element X in the primer layer obtained by X-ray photoelectron spectroscopy at an arbitrary depth in a region between a thickness direction of the primer layer from the interface up to 20 nm or more and 40 nm or less is set to C PR (atom%), C PR / C QD satisfies 0.10 or less.

[0020] <2> The wavelength conversion sheet according to <1>, wherein the element X is at least one selected from sulfur and phosphorus.

[0021] <3> The wavelength conversion sheet according to <1> or <2>, wherein the element X is sulfur.

[0022] <4> The wavelength conversion sheet according to any one of <1> to <3>, wherein a coefficient of variation of a proportion of the element X in a thickness direction of the primer layer obtained by X-ray photoelectron spectroscopy is 0.60 or more.

[0023] <5> The wavelength conversion sheet according to any one of <1> to <4>, wherein the primer layer contains a polyurethane-based resin and a polyester resin.

[0024] <6> The wavelength conversion sheet according to <5>, wherein the polyurethane-based resin is a resin obtained by reaction of a polyfunctional isocyanate having a (meth)acryloyl group and a hydroxyl group-containing compound.

[0025] <7> The wavelength conversion sheet according to <5> or <6>, wherein a molar ratio of isocyanate groups to hydroxyl groups (NCO / OH ratio) of the polyurethane-based resin is 1.1 or more.

[0026] <8> The wavelength conversion sheet according to any one of <5> to <7>, wherein the primer layer further contains a phenol-based antioxidant.

[0027] <9> The wavelength conversion sheet according to any one of <1> to <8>, wherein a barrier layer is further contained between the substrate layer and the primer layer.

[0028] <10> The wavelength conversion sheet according to <9>, wherein the barrier layer has a first barrier layer and a second barrier layer, the first barrier layer being an inorganic oxide layer.

[0029] <11> The wavelength conversion sheet according to <9> or <10>, wherein the substrate layer has a first substrate and a second substrate, the barrier layer and the primer layer being formed on one face of the first substrate, the second substrate being bonded to the other face of the first substrate via an adhesive layer.

[0030] <12> The wavelength conversion sheet according to any one of <1> to <11>, further comprising a diffusion layer.

[0031] <13> A backlight comprising: at least one light source that emits primary light; an optical sheet for light guiding or diffusion disposed adjacent to the light source; and a wavelength conversion sheet disposed on a light exit side of the optical sheet, wherein

[0032] The wavelength conversion sheet is the wavelength conversion sheet described in any one of <1> to <12>.

[0033] <14> A liquid crystal display device comprising a liquid crystal panel and the backlight source described in <13>.

[0034] Effects of the Invention

[0035] According to the present disclosure, a wavelength conversion sheet in which the adhesion between the phosphor layer and the primer layer is excellent even after a long-term environmental test can be obtained. By using the wavelength conversion sheet, a backlight source and a display device in which the phosphor layer is less likely to deteriorate over time can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a cross-sectional view illustrating one embodiment of the wavelength conversion sheet of the present disclosure.

[0037] Figure 2 is a cross-sectional view illustrating one embodiment of the backlight source of the present disclosure.

[0038] Figure 3 is a cross-sectional view illustrating another embodiment of the backlight source of the present disclosure. DETAILED DESCRIPTION

[0039] Hereinafter, an embodiment of the present disclosure will be described.

[0040] [Wavelength Conversion Sheet]

[0041] The wavelength conversion sheet of the present disclosure comprises a phosphor layer containing a phosphor, and a wavelength conversion sheet film provided on at least one surface side of the phosphor layer, the wavelength conversion sheet film being formed by at least laminating a base material layer and a primer layer, the primer layer being in contact with the phosphor layer, the phosphor layer and the primer layer containing an element X, the average value of the proportion of the element X in the phosphor layer obtained by X-ray photoelectron spectroscopy in a region from the interface between the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer being set to C QD (atom %), the proportion of the element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth in a region from the interface to 20 nm or more and 40 nm or less in the thickness direction of the primer layer being set to C PR (atom %), C PR / C QD satisfies 0.10 or less.

[0042] [Laminated Configuration]

[0043] Figure 1This is a schematic cross-sectional view illustrating one embodiment of the wavelength conversion sheet of this disclosure. Figure 1 The wavelength conversion sheet 100 is an example in which wavelength conversion sheet films 10 (10a, 10b) are provided on both surfaces of the phosphor layer 60.

[0044] The wavelength conversion film 10 of this disclosure has at least a primer layer 30 and a substrate layer 20. The primer layer 30 is in contact with the phosphor layer 60. Figure 1 In the example shown, in the substrate layer 20, the first substrate 20-1 and the second substrate 20-2 are bonded together via the adhesive layer 22.

[0045] Figure 1 The wavelength conversion films 10a and 10b also have a barrier layer 40 between the primer layer 30 and the substrate layer 20. Figure 1 In the middle, the barrier layer 40 is composed of two layers: the first barrier layer 42 and the second barrier layer 44.

[0046] in addition, Figure 1 The wavelength conversion films 10a and 10b also have a diffusion layer 50 on the side of the substrate layer 20 opposite to the side where the primer layer 30 is formed.

[0047] The wavelength conversion chip disclosed herein is not limited to the following configurations. Figure 1 The wavelength conversion sheet disclosed herein may, for example, have a surface side of the phosphor layer. Figure 1 The wavelength conversion film shown in the figure has a layered structure on another surface side having a similar structure to the one shown in the figure. Figure 1 Wavelength conversion films with different layer stacking structures. As long as the necessary conditions for the primer layer described above are met, the layer stacking structure of wavelength conversion films with different layer stacking structures is not limited. As a film having… Figure 1 Other wavelength conversion films with stacked layers not shown may be exemplified by films having the following stacked layer configurations. It should be noted that, unless otherwise specified, the layers in the following examples are... Figure 1 Same composition.

[0048] (1) It consists of layers of primer, substrate and diffusion layer in sequence.

[0049] (2) It consists of layers of primer and substrate layer in sequence.

[0050] (3) It consists of layers of primer, barrier layer, single-layer substrate layer and diffusion layer in sequence.

[0051] (4) It consists of a substrate layer consisting of a primer layer, a barrier layer, and a single layer in sequence.

[0052] (5) It consists of layers of primer, barrier layer, substrate layer and diffusion layer in sequence.

[0053] (6) The layer stack has, in order, a primer layer, a single-layer-constituted barrier layer, and a base material layer.

[0054] (7) The layer stack has, in order, a primer layer, a second barrier layer, a first barrier layer, a second barrier layer, a first barrier layer, a base material layer, and a diffusion layer.

[0055] (8) The layer stack has, in order, a primer layer, a second barrier layer, a first barrier layer, a second barrier layer, a first barrier layer, and a base material layer.

[0056] (9) The layer stack has, in order, a primer layer, a single-layer-constituted base material layer, a barrier layer, and a diffusion layer.

[0057] (10) The layer stack has, in order, a primer layer, a single-layer-constituted base material layer, and a barrier layer.

[0058] (11) The layer stack has, in order, a primer layer, a base material layer, a single-layer-constituted barrier layer, and a diffusion layer.

[0059] (12) The layer stack has, in order, a primer layer, a base material layer, and a single-layer-constituted barrier layer.

[0060] For the wavelength conversion sheet of the present disclosure, the film for wavelength conversion sheet of the present disclosure can be provided on one surface side of the phosphor layer, and a film other than the film for wavelength conversion sheet of the present disclosure, i.e., a film that does not satisfy the necessary conditions of the primer layer described above, can be provided on the other surface side of the phosphor layer. However, in view of the deterioration of the phosphor layer, it is preferable to stack the film for wavelength conversion sheet of the present disclosure on both surfaces of the phosphor layer.

[0061] [Adhesion]

[0062] As described later, the wavelength conversion sheet is manufactured by stacking the phosphor layer and the film for wavelength conversion sheet with the phosphor layer in contact with the primer layer. Therefore, for the wavelength conversion sheet, not only is the adhesion between the primer layer and the phosphor layer before the long-term environmental test (referred to as "initial adhesion") required to be good, but also the adhesion after the long-term environmental test (referred to as "adhesion over time") is required to be good.

[0063] As described later, the phosphor layer of the wavelength conversion sheet is formed by applying a resin composition that becomes a precursor of the phosphor layer to the surface of the primer layer of the film for wavelength conversion sheet and curing the resin composition. As a result of studies by the present inventors, it was found that when the precursor of the phosphor layer is applied to the primer layer, the primer layer is eroded by a solvent or the like, and the degree to which the components of the phosphor layer penetrate into the primer layer is related to the adhesion over time.

[0064] It is known that there is a tendency that the adhesion between layers improves due to the mixing of the components of the layers in contact. From this, it can be expected that when the components in the phosphor layer penetrate to a deep region inside the primer layer in a sufficient amount, both the initial adhesion and the adhesion over time will become good. However, the present inventors et al. found that, with respect to the adhesion over time, the more the penetration of the components of the phosphor layer into the primer layer, i.e., the fewer the components of the phosphor layer that penetrate into the primer layer in the region near the interface between the primer layer and the phosphor layer, the better.

[0065] The reason why the degree of penetration of the components of the phosphor layer into the primer layer is related to the adhesion over time is presumed as follows.

[0066] By applying the resin composition that becomes the precursor of the phosphor layer to the surface of the primer layer, the surface of the primer layer is eroded, and the components that constitute the phosphor layer in the resin composition diffuse toward the inside of the primer layer. Therefore, it is considered that after the phosphor layer is formed by curing, a region in which the components of the primer layer are compatible with the components that penetrate from the phosphor layer (hereinafter referred to as "compatible region") is formed in the primer layer. If the components of the phosphor layer penetrate into the primer layer more, the concentration of the components of the phosphor layer contained in the primer layer becomes high in the vicinity of the interface. In addition, because the components of the phosphor layer diffuse inside the primer layer, the components of the phosphor layer exist at a high concentration even at a position away from the interface. Therefore, a large compatible region that contains the components of the phosphor layer at a high concentration is formed. In contrast to this, in the case where the components of the phosphor layer that penetrate into the primer layer are small, a compatible region is formed in the vicinity of the interface between the primer layer and the phosphor layer, but the concentration of the components of the phosphor layer in the compatible region is also low.

[0067] From the viewpoint of initial adhesiveness, it is considered that the initial adhesiveness becomes good by forming a compatible region without depending on the penetration condition of the component of the phosphor layer. On the other hand, it is considered that the adhesiveness over time is caused by the relaxation of the strain generated in the phosphor layer. As described later, the phosphor layer is generally formed to be 10 μm or more and 200 μm or less. Therefore, a strain is generated in the inside of the phosphor layer due to the shrinkage caused by the curing of the phosphor layer, the swelling of the phosphor layer in a long-term environmental test, and the like. In a case where the component of the phosphor layer that penetrates into the primer layer is small, a compatible region is formed in the vicinity of the interface, but the component of the phosphor layer is small, and in addition, the other most part of the region is a region that does not contain the component of the phosphor layer, or even if it contains, it is a region that contains a very small amount. It is presumed that, by the distribution of the component of the phosphor layer in the primer layer described above, the strain of the phosphor layer is easily relaxed by the primer layer, and good adhesiveness can be ensured even after a long-term environmental test. On the other hand, in a case where the component of the phosphor layer that penetrates into the primer layer is large, and the component of the phosphor layer extends to the inside away from the interface at a high concentration, the compatible region shows the same behavior as the phosphor layer, and thus the primer layer is difficult to relax the strain accompanying the shrinkage and swelling of the phosphor layer. As a result, it is presumed that, over time, peeling is easily generated at the interface between the primer layer and the phosphor layer due to the strain generated in the primer layer and the phosphor layer, and thus the adhesiveness over time decreases.

[0068] [About Element X]

[0069] Element X is an element included in the component of the phosphor layer that is a precursor of the phosphor layer but not included in the component of the primer layer that is a precursor of the primer layer. The component containing Element X penetrates from the phosphor layer into the primer layer due to the contact of the phosphor layer with the primer layer, and Element X is transferred into the primer layer. Therefore, when the wavelength conversion sheet is produced, both the phosphor layer and the primer layer contain Element X, and the Element X in the primer layer is derived from the component transferred from the phosphor layer to the primer layer.

[0070] In the present disclosure, with a view to Element X, the degree of penetration of the component of the phosphor layer into the primer layer is indicated by the concentration of Element X in the primer layer as an index.

[0071] Specifically, Element X is at least one selected from the group consisting of sulfur and phosphorus. These elements are components that constitute the phosphor layer. Among them, Element X is preferably sulfur. Sulfur is an element from a mercaptan compound in the phosphor layer. Phosphorus is an element from a phosphorus-based photopolymerization initiator in the phosphor layer.

[0072] [About Distribution of Element X]

[0073] The distribution of Element X in the thickness direction of the primer layer and the phosphor layer can be analyzed by X-ray photoelectron spectroscopy (hereinafter referred to as "XPS").

[0074] The average value of the proportion of element X in the phosphor layer obtained by X-ray photoelectron spectroscopy in the region from the interface of the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer is defined as C QD (atomic %), the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at an arbitrary depth in the region from the interface to between 20 nm or more and 40 nm or less in the thickness direction of the primer layer is defined as C PR (atomic %). In the present disclosure, C PR / C QD It is necessary to satisfy 0.10 or less.

[0075] The proportion C of element X in the primer layer PR , and the proportion C of element X in the phosphor layer QD can be obtained by peeling the interface of the primer layer and the phosphor layer after the wavelength conversion sheet is produced, and performing element analysis on the peeled surfaces of the primer layer and the phosphor layer in the respective thickness directions using XPS.

[0076] Element analysis based on XPS can be performed, for example, by the following steps.

[0077] First, it is determined whether the interface of the phosphor layer and the primer layer is peeled. This determination can be performed by XPS analysis, but can also be performed by other analysis methods. Hereinafter, a determination method using XPS analysis is described.

[0078] For each of the peeled surfaces of the phosphor layer and the primer layer, a full spectrum scan spectrum is obtained, and the elements contained in the measurement surface are identified. In the case where an element (referred to as "element Z") contained in the resin composition that is a precursor of the primer layer but not contained in the resin composition that is a precursor of the phosphor layer is detected on the peeled surface on the primer layer side but not detected on the peeled surface on the phosphor layer side by XPS analysis of the peeled surfaces, it can be determined that peeling has occurred at the interface of the phosphor layer and the primer layer. For example, in the case where the primer layer contains a urethane-based resin and the phosphor layer contains a nitrogen-free resin, the element Z is nitrogen. The peeled surface on the primer layer side and the peeled surface on the phosphor layer side are considered to be the interface of the primer layer and the phosphor layer, and each of the peeled surfaces is defined as "depth 0 nm".

[0079] In the case where it is determined that peeling has occurred at the interface of the phosphor layer and the primer layer, the proportion (unit: atomic %) of each element detected is calculated using a narrow spectrum.

[0080] After XPS analysis of the peeled surface of the primer layer, etching is performed from the peeled surface under prescribed conditions, and a new measurement surface is exposed. XPS analysis is performed on the surface exposed after etching, and the proportion of each element is calculated. By repeatedly performing this operation, the depth distribution of each element can be obtained for the thickness direction of the primer layer.

[0081] After performing XPS analysis of the stripped surface of the phosphor layer, etching is performed from the stripped surface under prescribed conditions to expose a new measurement surface. XPS analysis is performed on the surface exposed after etching, and the proportions of the respective elements are calculated. By repeatedly performing this operation, the depth distribution of the respective elements can be obtained for the thickness direction of the phosphor layer.

[0082] Element X is a component that constitutes the phosphor layer, and thus the amount of element X present in the phosphor layer is sufficiently high relative to the amount of element X transferred to the primer layer. In addition, it can be said that even if a portion of element X is transferred to the primer layer, the concentration of element X is substantially constant throughout the phosphor layer. Therefore, C QD defined as the average of the proportions of element X in the phosphor layer in the region from the interface (depth 0 nm) to a depth of 400 nm in the thickness direction, but can be considered as the average of the proportion of element X throughout the phosphor.

[0083] The etching amount varies depending on the conditions of etching, the material of the measurement object, and the like, and thus even if the etching time is adjusted, it is sometimes difficult to expose the measurement surface at a depth of 400 nm for XPS analysis. However, as described above, it can be said that the concentration of element X is substantially constant throughout the phosphor layer, and thus in cases where a measurement point at a depth of 400 nm cannot be obtained, the average of the proportions of element X from the interface (depth 0 nm) to a measurement point closest to 400 nm at a depth of less than 400 nm is calculated.

[0084] In cases where the components in the phosphor layer easily penetrate into the primer layer, the components of the phosphor layer that are transferred to the primer layer penetrate in large amounts, and thus the amount of element X transferred to the primer layer also increases. Therefore, the proportion of element X in the primer layer in the vicinity of the interface increases. In addition, element X that is transferred to the primer layer also diffuses into the interior, and the proportion of element X also increases in regions away from the interface. On the other hand, in cases where the amount of components in the phosphor layer that penetrate into the primer layer is small, the proportion of element X in the primer layer in the vicinity of the interface is relatively low, and element X is difficult to detect in regions away from the interface. In this way, the distribution of element X detected by XPS in the primer layer differs depending on the degree of penetration of the components of the phosphor layer.

[0085] It is considered that the proportion of element X detected in the primer layer varies depending on the concentration of element X in the phosphor layer. Therefore, C PR / C QD is used as an index indicating the degree of penetration of the components in the phosphor layer into the primer layer. C PR / C QD is lower, the more the penetration of the components of the phosphor layer into the primer layer can be suppressed.

[0086] As described later, the primer layer is preferably provided with a thickness in the range of 0.2 to 10 μm. The "region between 20 nm or more and 40 nm or less in the thickness direction from the interface with the phosphor layer" corresponds to a region that goes to some extent into the interior of the primer layer from the interface. As described above, in the case where the permeation of the components of the phosphor layer is sufficiently suppressed, some extent of element X is detected in the vicinity of the interface of the primer layer, but there is a tendency that the concentration of element X decreases as it goes toward the interior in the thickness direction. Therefore, in the case where the permeation of the components of the phosphor layer is sufficiently suppressed, C PR / C QD decreases at some extent from the interface (in a region between 20 nm or more and 40 nm or less in the thickness direction of the primer layer from the interface). In contrast to this, in the case where the components of the phosphor layer permeate a large amount into the primer layer, C PR / C QD increases at some extent from the interface. It can be said that, by making C PR / C QD 0.10 or less at any depth in a region between 20 nm or more and 40 nm or less in the thickness direction of the primer layer from the interface with the phosphor layer, the diffusion of the components constituting the phosphor layer into the primer layer can be suppressed. In the present disclosure, C PR / C QD is preferably 0.08 or less, more preferably 0.06 or less, and further preferably 0.04 or less.

[0087] As described above, sometimes it is difficult to expose a measurement surface of a specific depth by etching to perform XPS analysis. Therefore, in the present disclosure, it is defined as "any depth in a region between 20 nm or more and 40 nm or less in the thickness direction of the primer layer from the interface". A measurement surface of any depth between 20 nm or more and 40 nm or less in the thickness direction can be exposed by adjusting the etching conditions, etching time, and the like.

[0088] Depending on the etching conditions and the like, sometimes a plurality of measurement points are obtained in a region between 20 nm or more and 40 nm or less in the thickness direction from the interface. In the present disclosure, in the case where a plurality of measurement points are obtained, C PR / C QD is required to be 0.10 or less in all of the measurement points.

[0089] In the present disclosure, in the case where the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth in a region between 1 nm or more and less than 20 nm in the thickness direction of the primer layer from the interface with the phosphor layer is defined as C PR-S (atom %), CPR-S / C QD It is preferably 0.04 or more and 0.20 or less, more preferably 0.04 or more and 0.15 or less, further preferably 0.04 or more and 0.10 or less. The region of 1 nm or more and less than 20 nm between in the thickness direction of the primer layer from the interface with the phosphor layer means a region corresponding to the vicinity of the interface of the primer layer with the phosphor layer. In the region in the vicinity of the interface, C PR-S / C QD 0.04 or more and 0.20 or less means allowing permeation of the components of the phosphor layer, and suppressing permeation as much as possible. By making C PR-S / C QD In the above range, both initial adhesion and adhesion over time are good. Note that in the case where a plurality of measurement points are obtained in this region, it is preferable that C PR-S / C QD satisfy the above range.

[0090] Note that the interface of the primer layer sometimes becomes a different element distribution from the inside when the depth distribution is measured using XPS due to surface oxidation, adsorption of moisture, and the like. Therefore, in the present disclosure, the interface (depth 0 nm) is excluded from the "region in the vicinity of the interface".

[0091] In the present disclosure, the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth in a region more than 40 nm from the interface with the phosphor layer in the thickness direction of the primer layer is defined as C PR-I (atomic %) in the case where C PR-I / C QD It is preferably 0.10 or less, more preferably 0.05 or less, further preferably 0.01 or less. Note that in the case where a plurality of measurement points are obtained in this region, it is preferable that C PR-I / C QD satisfy the above range.

[0092] Satisfying the above range in a region more than 40 nm from the interface with the phosphor layer in the thickness direction of the primer layer means that permeation of the components of the phosphor layer into a deep region in the inside of the primer layer is suppressed.

[0093] In the present disclosure, C PR / C QD 0.10 or less, C PR / C PR-S It is preferably 0.60 or less. C PR / C PR-SThe ratio of the element in the region that corresponds to the degree of penetration into the inside of the primer layer from the interface is preferably 0.20 or more, more preferably 0.30 or more, and even more preferably 0.40 or more, relative to the ratio of the element X at the region near the interface.C PR / C PR-S Satisfying the above range means that the element X is not an element of the component contained in the resin composition that constitutes the precursor of the primer layer, but is an element from the component contained in the resin composition that constitutes the precursor of the phosphor layer.C PR / C PR-S Satisfying the above range means that the element X is not an element of the component contained in the resin composition that constitutes the precursor of the primer layer, but is an element from the component contained in the resin composition that constitutes the precursor of the phosphor layer.C PR / C PR-S It is preferably 0.55 or less, more preferably 0.50 or less, and even more preferably 0.40 or less.

[0094] In the present disclosure, the coefficient of variation of the ratio of the element X in the thickness direction of the primer layer obtained by X-ray photoelectron spectroscopy is preferably 0.60 or more. This coefficient of variation is an index indicating the deviation of the element X in the thickness direction of the primer layer. As described above, it can be said that the concentration of the element X is substantially constant in the entire phosphor layer. In this case, the coefficient of variation of the ratio of the element X in the thickness direction of the phosphor layer becomes a low value. In the case where the penetration of the component in the phosphor layer into the primer layer is suppressed, the element X is detected in the primer layer near the interface, but it is difficult to detect the element X in the region away from the interface. In this case, the coefficient of variation of the ratio of the element X in the thickness direction of the primer layer becomes high. On the other hand, in the case where the component in the phosphor layer that penetrates into the primer layer is much, and the component also diffuses into the inside of the primer layer, there is a tendency that the difference between the ratio of the element X near the interface and the ratio of the element X in the region away from the interface becomes small. At this time, the coefficient of variation of the ratio of the element X in the thickness direction of the primer layer becomes low. By making the coefficient of variation 0.60 or more, it can be said that the penetration of the component in the phosphor layer into the primer layer is suppressed. The coefficient of variation is more preferably 0.75 or more, and even more preferably 1.00 or more. The upper limit value of the coefficient of variation is preferably 5.00, and more preferably 4.00.

[0095] In calculating the coefficient of variation, the XPS analysis and etching are repeatedly performed in a manner that the ratio of the element X is obtained at at least 8 points in the thickness direction of the primer layer, and the depth distribution of the element X is obtained. Then, using the ratio of the element X at at least 8 points, the average value and the standard deviation are calculated, and the coefficient of variation is obtained by dividing the standard deviation by the average value.

[0096] In the wavelength conversion sheet of the present disclosure, the penetration of the component of the phosphor layer into the primer layer is suppressed, and the ratio of the element X at any depth in the region between 20 nm or more and 40 nm or less in the thickness direction of the primer layer from the interface is C PR / C QDThe reason why the value of 0.10 or less is satisfied is presumed to be a combined effect of the following (1) to (3).

[0097] (1) Component of resin constituting primer layer

[0098] It is presumed that the higher the glass transition temperature of the resin contained in the resin composition that is a precursor of the primer layer, the more the penetration of the components of the phosphor layer into the primer layer is inhibited.

[0099] The primer layer in the present disclosure preferably contains a polyurethane-based resin and a polyester resin as described later. As a means to increase the glass transition temperature of the resin that is a precursor of the primer layer, there are a means to use a polyurethane-based resin having a high glass transition temperature, a means to use a polyester resin having a high glass transition temperature, and a means to use them in combination. Among them, it is preferable to use a polyester resin having a high glass transition temperature, and more preferable to use a polyurethane-based resin having a high glass transition temperature and a polyester resin having a high glass transition temperature in combination.

[0100] The resin constituting the primer layer has a high glass transition temperature, and tends to have a high molecular weight (weight average molecular weight) and a high density. Therefore, it is presumed that the primer layer formed of such a resin has an effect of hindering the diffusion of the components of the phosphor layer. In addition, it is presumed that the primer layer formed of such a resin is also a major reason why it is not easily eroded by the solvent contained in the resin composition that is a precursor of the phosphor layer.

[0101] The glass transition temperature of the resin composition that is a precursor of the primer layer is preferably -20°C or higher, and more preferably 0°C or higher. The glass transition temperature of the resin composition is preferably 120°C or lower, and more preferably 100°C or lower. That is, the glass transition temperature of the resin composition is preferably -20°C or higher and 120°C or lower, and more preferably 0°C or higher and 100°C or lower.

[0102] The glass transition temperature of the polyurethane-based resin is preferably -20°C or higher, and more preferably 0°C or higher. The glass transition temperature of the polyurethane-based resin is preferably 120°C or lower, and more preferably 100°C or lower. That is, the glass transition temperature of the polyurethane-based resin is preferably -20°C or higher and 120°C or lower, and more preferably 0°C or higher and 100°C or lower.

[0103] The glass transition temperature of the polyester resin is preferably 0°C or higher, and more preferably 20°C or higher. The glass transition temperature of the polyester resin is preferably 150°C or lower, and more preferably 120°C or lower. That is, the glass transition temperature of the polyester resin is preferably 0°C or higher and 150°C or lower, and more preferably 20°C or higher and 120°C or lower.

[0104] Note that the glass transition temperature is an intermediate point glass transition temperature T obtained by the method described in item 9.3(l) of JIS K 7121:1987 from a DTA curve obtained by differential thermal analysis (DTA) in accordance with JIS K 7121:1987 mg .

[0105] (2) Silane coupling agent

[0106] The primer layer in the present disclosure preferably contains a silane coupling agent having a reactive group. It is presumed that, by containing a silane coupling agent, the crosslinking density is increased at the time of curing the resin composition that is the precursor of the primer layer, a primer layer having a denser crosslinking structure is formed, and thus the penetration of the components of the phosphor layer is inhibited.

[0107] (3) Solvent contained in the precursor for forming the phosphor layer

[0108] As described later, the phosphor layer is generally formed by applying a resin composition (precursor) containing a phosphor and an encapsulating resin to the surface of the primer layer, or laminating a film for wavelength conversion sheet in such a manner that the surface of the primer layer is in contact with the applied resin composition, and then curing the resin composition. In the resin composition for forming the phosphor layer, a solvent is added for the purpose of viscosity adjustment or the like. It is considered that, depending on the kind of the solvent, the surface region of the primer layer is invaded during the period before the curing of the phosphor layer, and the components of the phosphor layer easily enter the inside of the primer layer. It is presumed that, by selecting a solvent that does not easily erode the components of the resin composition constituting the primer layer, the penetration of the components of the phosphor layer can be inhibited. For example, in the case where the primer layer contains a polyurethane-based resin, there is a tendency that the surface region of the primer layer is easily eroded by a solvent having a hydrophilic group (e.g., an alcohol-based solvent such as isopropyl alcohol), and thus it is preferable to use a hydrophobic solvent (e.g., methyl ethyl ketone, toluene, ethyl acetate).

[0109] Hereinafter, each layer of the wavelength conversion sheet of the present disclosure is described in detail.

[0110] [Primer layer]

[0111] The primer layer ensures good adhesion to the phosphor layer at the time of manufacturing the wavelength conversion sheet, prevents peeling of the film for wavelength conversion sheet from the phosphor layer in a high-temperature high-humidity environment, and plays a role in preventing the deterioration of the phosphor layer.

[0112] The primer layer can be constituted by a single layer or by a plurality of primer layers laminated, and is particularly preferably constituted by a single layer. Note that, in the case where a plurality of primer layers are laminated, the primer layer in contact with the phosphor layer satisfies the above-described C PR / C QD .

[0113] In the present disclosure, the primer layer preferably contains a polyurethane-based resin and a polyester resin.

[0114] < Polyurethane-based resin >

[0115] The primer layer contains a polyurethane-based resin, thereby easily relaxing a strain generated due to swelling or shrinkage of the phosphor layer when the wavelength conversion sheet is manufactured, and easily making the initial adhesion and the adhesion over time of the phosphor layer to the primer layer good. In particular, by using a polyurethane-based resin showing a glass transition temperature within the above range, penetration of components of the phosphor layer into the primer layer is suppressed, and C PR / C QD is easily 0.10 or less, and thus is preferred.

[0116] The primer layer containing a polyurethane-based resin can be confirmed by detecting a urethane bond using X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), nuclear magnetic resonance method (NMR), gas chromatography mass spectrometry (GCMS), or the like.

[0117] The polyurethane-based resin is a one-liquid or two-liquid type polyurethane-based resin obtained by the reaction of a polyfunctional isocyanate and a hydroxyl group-containing compound.

[0118] The polyfunctional isocyanate and the hydroxyl group-containing compound can each be used only one kind, or a plurality of kinds can be used.

[0119] As the polyfunctional isocyanate, aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, poly-methylene polyphenylene polyisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and the like can be given. The polyfunctional isocyanate can be used as an adduct, a biuret, an isocyanurate, and the like, which are modified to have a high molecular weight, or can be used as a block. The modified product and the block can have a functional group such as a hydroxyl group, a carboxyl group, an epoxy group, an amino group, a mercapto group, a vinyl group, an acryloyl group, a methacryloyl group, and the like. Among them, a (meth)acryloyl group-containing polyisocyanate is preferably used. That is, the polyurethane-based resin of the present disclosure contains a polyurethane-based resin obtained by the reaction of a polyfunctional isocyanate having a (meth)acryloyl group and a hydroxyl group-containing compound.

[0120] In addition, as the hydroxyl group-containing compound, polyether polyols, polyester polyols, polyester urethane polyols, polyacrylate polyols, and the like can be given. Among them, a polyester polyol is preferred.

[0121] The NCO / OH ratio of the polyurethane-based resin is preferably 1.1 or greater, more preferably 1.2 or greater, and further preferably 1.3 or greater. By having an NCO / OH ratio of 1.1 or greater, the initial adhesion is easily made good. Note that when the NCO / OH ratio is high, the primer layer has tackiness. Therefore, the NCO / OH ratio is preferably 4.0 or less, and more preferably 3.0 or less.

[0122] The molecular weight (weight average molecular weight) of the polyurethane-based resin is preferably 1,000 or greater, and more preferably 2,000 or greater, and is preferably 100,000 or less, and more preferably 80,000 or less. That is, the molecular weight (weight average molecular weight) of the polyurethane-based resin is preferably 1,000 or greater and 100,000 or less, and more preferably 2,000 or greater and 80,000 or less.

[0123] By having the molecular weight of the polyurethane-based resin within the above range, the C PR / C QD is easily 0.10 or less.

[0124] <Polyester Resin>

[0125] By having the primer layer contain a polyester resin, the C PR / C QD is easily 0.10 or less, and the initial adhesion and the adhesion over time of the primer layer to the phosphor layer can be improved. It is particularly preferable to use a polyester resin that exhibits a glass transition temperature within the above range. This polyester resin is a different component from the polyester that forms the backbone of the polyol component of the polyurethane resin.

[0126] The molecular weight (weight average molecular weight) of this polyester resin is preferably 2,000 or greater, and more preferably 5,000 or greater, and is preferably 700,000 or less, and more preferably 500,000 or less. That is, the molecular weight (weight average molecular weight) of this polyester resin is preferably 2,000 or greater and 700,000 or less, and more preferably 5,000 or greater and 500,000 or less.

[0127] Note that in the present specification, the weight average molecular weight is the average molecular weight as determined by GPC analysis and converted to standard polystyrene.

[0128] The proportion of the polyester resin is preferably 5 parts by mass or more, more preferably 20 parts by mass or more, with respect to 100 parts by mass of the polyurethane resin. In addition, the proportion of the polyester resin is preferably 60 parts by mass or less, more preferably 40 parts by mass or less, with respect to 100 parts by mass of the polyurethane resin. That is, the proportion of the polyester resin is preferably 5 parts by mass or more and 60 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less, further preferably 20 parts by mass or more and 40 parts by mass or less, with respect to 100 parts by mass of the polyurethane resin. By setting the proportion of the polyester resin to the above range, penetration of components from the phosphor layer is suppressed, and C PR / C QD easily 0.10 or less, and the initial adhesion and the adhesion over time of the primer layer to the phosphor layer can be improved.

[0129] <Phenolic antioxidant>

[0130] In the present disclosure, the primer layer preferably further contains a phenolic antioxidant. By the primer layer containing a phenolic antioxidant, the adhesion over time can sometimes be made more favorable.

[0131] As specific examples of the phenolic antioxidant, dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-butylidenebis(3-methyl-6-tert-butylphenol), 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the like can be given.

[0132] <Silane coupling agent>

[0133] In the present disclosure, the primer layer preferably further contains a silane coupling agent. In the silane coupling agent, a functional group at one end of the molecule, which is typically chlorine, alkoxy, or acetoxy, or the like, is hydrolyzed to form a silanol group (Si-OH). As a result, the resin composition of the primer layer is modified by covalent bonds or the like to form a firm bond. Therefore, it is considered that by compounding the silane coupling agent in the resin composition of the primer layer, the crosslinking density can be improved, and penetration of components from the phosphor layer can be suppressed. In addition, in a configuration in which a barrier layer is provided, the adhesion of the primer layer to the barrier layer (particularly, the coating layer) can be improved.

[0134] In the present disclosure, in order to improve the adhesion of the primer layer to the phosphor layer and the adhesion of the barrier layer to the primer layer, a silane coupling agent having a reactive group is preferably used. As the reactive group, a vinyl group, a (meth)acryl group, an amino group, an epoxy group, a mercapto group, and the like can be given. Particularly, a silane coupling agent having a (meth)acryl group is preferably used. It is considered that by using a silane coupling agent having a (meth)acryl group, the crosslinking density can be further increased, and the penetration of components from the phosphor layer is suppressed, and C PR / C QD It is easy to control to be 0.10 or less.

[0135] As the silane coupling agent, an organofunctional silane monomer having a bireactive group can be used. For example, one or more kinds of γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris(β-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltriethoxysilane, bis(β-hydroxyethyl)-γ-aminopropyltriethoxysilane, an aqueous solution of γ-aminopropylsilicone, and the like can be used. Among them, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane are preferable.

[0136] The above-described silane coupling agent is preferably contained in 1% by mass or more, and more preferably 2% by mass or more in the total amount of the primer layer. When the content of the silane coupling agent is in the above-described range, the initial adhesion between the primer layer and the phosphor layer, and the adhesion between the barrier layer and the primer layer can be further improved. In addition, good adhesion between the primer layer and the phosphor layer can be maintained over time. Note that in order to make the elongation of the primer layer good and to suppress the generation of cracks in the primer layer, the silane coupling agent is preferably contained in 30% by mass or less, and more preferably 20% by mass or less in the total amount of the primer layer.

[0137] In addition, in the present disclosure, surface treatment such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen or nitrogen, glow discharge treatment, oxidation treatment using a chemical agent, or the like can be performed on the surface of the primer layer (interface with the phosphor layer) after the primer layer is formed.

[0138] In the present disclosure, the primer layer can further contain a filler. The filler has the effect of adjusting the viscosity or the like of the coating liquid used to form the primer layer, improving coating adaptability, or the like. As the filler, for example, a powder such as calcium carbonate, barium sulfate, alumina white, silica, talc, glass powder, or the like, a resin powder, or the like can be used.

[0139] The primer layer can further contain a stabilizer, a crosslinking agent, a lubricant, an ultraviolet absorber, other additives, or the like as needed.

[0140] The thickness of the primer layer is not particularly limited, and is preferably 0.07 μm or more, more preferably 0.10 μm or more, further preferably 0.15 μm or more, particularly preferably 0.20 μm or more. If the primer layer is too thick, the handling property and the productivity decrease, and thus the thickness of the primer layer is preferably 10 μm or less, more preferably 7 μm or less, further preferably 5 μm or less, particularly preferably 3 μm or less.

[0141] In order to efficiently convert light from a light source, the primer layer of the present embodiment is preferably high in total light transmittance measured based on JIS K 7361-1: 1997. Specifically, the primer layer of the present embodiment is preferably 85% or more, more preferably 90% or more in total light transmittance measured based on JIS K 7361-1: 1997 when the primer layer is formed on a PET film (film thickness: 12 μm).

[0142] [Substrate Layer]

[0143] The substrate layer mainly functions as a support for the primer layer. The substrate layer preferably has high light transmittance. Specifically, the total light transmittance of the substrate layer according to JIS K 7361-1: 1997 is preferably 85% or more, more preferably 90% or more.

[0144] The material of the substrate layer is not particularly limited as long as it is a resin film that does not impair the function of the wavelength conversion sheet. As the substrate layer, for example, a resin such as polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polypropylene (PP), a nylon resin, an amorphous polyarylate, a polysulfone, a polyethersulfone, a polyetherimide, a fluororesin, a liquid crystal polymer, or the like can be given. In order to obtain transparency, heat resistance, and the like, polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) is preferably used as the substrate layer. In addition, in order to obtain the oxygen permeability and the water vapor permeability described above, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), or a nylon resin is preferably used as the substrate layer.

[0145] The substrate layer can be a resin film composed of a single layer, or can be a plurality of resin films bonded via an adhesive layer. In the example shown in FIG. 1, the substrate layer 20 is composed of a first substrate 20-1 and a second substrate 20-2 laminated together. In this case, the first substrate 20-1 serves as a support when the primer layer 30 is formed. The second substrate 20-2 functions to increase the thickness of the entire substrate layer 20 and to impart rigidity to the wavelength conversion sheet film 10. Figure 1 The thickness of the entire substrate layer is not particularly limited, and is preferably 8 μm or more and 200 μm or less, more preferably 8 μm or more and 150 μm or less. In the case where the wavelength conversion sheet film is manufactured in a roll-up manner, the thickness of the entire substrate layer is preferably 125 μm or less. On the other hand, by increasing the thickness of the entire substrate layer, the gas barrier properties of the substrate layer with respect to oxygen and water vapor can be utilized. In this case, the barrier layer can be omitted. In order to ensure the gas barrier properties required of the substrate layer without providing the barrier layer, the thickness of the entire substrate layer is preferably 50 μm or more, more preferably 75 μm or more.

[0146] In the case where the substrate layer is composed of a plurality of resin films, the thickness of the first substrate that serves as a support for the primer layer is preferably 8 μm or more and 50 μm or less, more preferably 8 μm or more and 25 μm or less, further preferably 8 μm or more and 20 μm or less. If the first substrate has the above thickness, the handleability is good when the primer layer is manufactured in a roll-up manner. In addition, the thickness of the second substrate is preferably 8 μm or more and 150 μm or less, more preferably 8 μm or more and 100 μm or less. If the second substrate has the above thickness, the wavelength conversion sheet film can be imparted with moderate rigidity. Furthermore, the handleability is good when the wavelength conversion sheet film is manufactured in a roll-up manner. Note that in the case where the gas barrier properties are ensured by the substrate layer as described above, the thickness of the second substrate is preferably 40 μm or more, more preferably 50 μm or more.

[0147]

[0148] ​The adhesive constituting the adhesive layer 22 is not particularly limited as long as it satisfies good adhesion between the substrate layers and the optical properties required for the wavelength conversion sheet. For example, as the adhesive, a polyacrylate-based adhesive composed of, for example, a homopolymer of polyvinyl acetate-based adhesive, ethyl ester, butyl ester, 2-ethylhexyl ester of acrylic acid, or the like, or a copolymer of methyl methacrylate, acrylonitrile, styrene, or the like, a cyanoacrylate-based adhesive, a copolymer of ethylene composed of, for example, a monomer of vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, or the like, a cellulose-based adhesive, a polyester-based adhesive, a polyamide-based adhesive, a polyimide-based adhesive, an amino resin-based adhesive composed of, for example, urea resin or melamine resin, a phenol resin-based adhesive, an epoxy-based adhesive, a polyurethane-based adhesive, a reactive (meth)acrylic-based adhesive, a rubber-based adhesive composed of, for example, chloroprene rubber, nitrile rubber, styrene-diene rubber, or the like, a silicone-based adhesive, an inorganic-based adhesive composed of, for example, alkali metal silicate, low-melting glass, or the like, and the like can be used. The composition system of the adhesive constituting the adhesive layer can be any of an aqueous type, a solution type, an emulsion type, a dispersion type, or the like, and in addition, the form thereof can be any of a film shape, a sheet shape, a powder shape, a solid shape, or the like, and furthermore, the adhesive mechanism thereof can be any of a chemical reaction type, a solvent evaporation type, a hot melting type, a hot pressing type, or the like.

[0149] Note that, instead of the above-described adhesive, for example, a thermosetting resin, a resin containing a crosslinking agent in a thermoplastic resin, or the like can be used to form the adhesive layer. Alternatively, a thermoplastic resin such as EVA, an ionomer, polyvinyl butyral (PVB), a polyethylene-based resin, or the like can be extruded between the substrates by extrusion lamination to form the adhesive layer.

[0150] In order to improve adhesion to the primer layer or the barrier layer, or the like, a desired surface treatment can be performed on the surface of the side on which the primer layer is provided of the substrate layer in advance. As the surface treatment, for example, a corona discharge treatment, an ozone treatment, a low-temperature plasma treatment using oxygen or nitrogen, or the like, a glow discharge treatment, an oxidation treatment using a chemical agent, or the like can be given.

[0151] In addition, as a method of improving adhesion to the primer layer or the barrier layer, a base layer such as an anchor coating layer, an adhesive layer, or the like can be formed in advance.

[0152] As the base layer, for example, a resin composition in which a polyester-based resin, a polyamide-based resin, a polyurethane-based resin, an epoxy-based resin, a phenol-based resin, a (meth)acrylic-based resin, a polyvinyl acetate-based resin, a polyolefin-based resin such as polyethylene or polypropylene, or a copolymer or modified resin thereof, a cellulose-based resin, or the like is used as a main component of a carrier can be used.

[0153] [Barrier Layer]

[0154] The barrier layer is a layer that imparts a gas barrier property to the wavelength conversion sheet-use film. The barrier layer is a layer that is arbitrarily provided depending on the gas barrier property required of the wavelength conversion sheet-use film. The barrier layer can be provided on the side of the base material layer opposite the primer layer, or between the base material layer and the primer layer. In order to prevent damage to the barrier layer during the manufacturing process of the wavelength conversion sheet-use film and the manufacturing process of the wavelength conversion sheet, and in order to suppress deterioration of the phosphor layer from the end portion of the sheet when the wavelength conversion sheet is manufactured, the barrier layer is preferably provided between the base material layer and the primer layer.

[0155] As the layer constituting the barrier layer, there are an "inorganic oxide layer formed by vapor deposition of an inorganic oxide", an "inorganic oxide layer formed by a sol-gel method", a "coating layer formed by coating a coating agent containing an organic component such as a water-soluble polymer", a "coating layer formed by coating a coating agent containing an inorganic oxide component and an organic component such as a water-soluble polymer", and a "layer containing a reactant of a composition containing a metal oxide and a phosphorus compound (hereinafter referred to as a "metal phosphoric reactant layer")".

[0156] In the example shown in FIG. 1, the barrier layer 40 is constituted by laminating the first barrier layer 42 and the second barrier layer 44. In the example shown in FIG. 2, the barrier layer 40 is constituted by laminating the first barrier layer 42, the second barrier layer 44, and the third barrier layer 46. Figure 1 In the example shown in FIG. 1, the first barrier layer 42 is located on the side of the base material layer 20. The second barrier layer 44 is in contact with the primer layer 30. Figure 1 The barrier layer of the present disclosure is not limited to the laminated constitution of the above-described layers. As the constitution of the barrier layer in the present disclosure, there are a constitution of a single layer selected from the group consisting of the layers constituting the above-described barrier layer, a constitution of a plurality of layers laminated by selecting one from the group, a constitution of two or more layers alternately laminated by selecting two or more from the group (i.e., a constitution including at least a first barrier layer and a second barrier layer), and the like.

[0157] Figure 1 As the constitution of the barrier layer including a first barrier layer and a second barrier layer, there are a constitution of two layers exemplified in the above-described examples, a constitution of sequentially laminating a first barrier layer, a second barrier layer, and a third barrier layer from the side of the base material layer, a constitution of sequentially laminating a first barrier layer, a second barrier layer, a third barrier layer, and a fourth barrier layer from the side of the base material layer, and the like. In this case, the materials of adjacent layers are different from each other.

[0158] As the constitution of the barrier layer including a first barrier layer and a second barrier layer, there are a constitution of two layers exemplified in the above-described examples, a constitution of sequentially laminating a first barrier layer, a second barrier layer, and a third barrier layer from the side of the base material layer, a constitution of sequentially laminating a first barrier layer, a second barrier layer, a third barrier layer, and a fourth barrier layer from the side of the base material layer, and the like. In this case, the materials of adjacent layers are different from each other. Figure 1 In the case where the barrier layer includes a first barrier layer and a second barrier layer, the first barrier layer is preferably an inorganic oxide layer. The second barrier layer is preferably the coating layer described above.

[0159]

[0160] ​​When the barrier layer includes the first barrier layer, the second barrier layer, and the third barrier layer, the first barrier layer on the substrate layer 20 side is preferably an inorganic oxide layer. The second barrier layer is preferably a coating layer. The third barrier layer is preferably an inorganic oxide layer or a coating layer. In the case where the third barrier layer is a coating layer, the material is different from that of the coating layer of the second barrier layer. The third barrier layer is preferably an inorganic oxide layer in view of barrier properties, damage to the barrier layer, and the like.

[0161] When the barrier layer includes the first barrier layer, the second barrier layer, the third barrier layer, and the fourth barrier layer, the first barrier layer on the substrate layer 20 side is preferably an inorganic oxide layer. The second barrier layer is preferably a coating layer. The third barrier layer and the fourth barrier layer are each preferably one selected from an inorganic oxide layer and a coating layer. However, the materials of the adjacent layers are different from each other for the third barrier layer and the fourth barrier layer. The third barrier layer is preferably an inorganic oxide layer and the fourth barrier layer is preferably a coating layer in view of barrier properties, damage to the barrier layer, and the like.

[0162] <Inorganic Oxide Layer>

[0163] The inorganic oxide layer can be exemplified by a layer including aluminum oxide, silicon oxide, magnesium oxide, or a mixture thereof. The inorganic oxide layer is preferably a thin film layer having aluminum oxide or silicon oxide as a main component from the viewpoints of gas barrier properties, transparency, productivity, and the like.

[0164] Methods of forming the inorganic oxide layer can be exemplified by a method of forming by vapor deposition of an inorganic oxide, a method of forming by a sol-gel method. As a method of forming a vapor deposition film, for example, a physical vapor deposition method (Physical Vapor Deposition method, PVD method) such as a vacuum evaporation method, a sputtering method, and an ion plating method, or a chemical vapor deposition method (Chemical Vapor Deposition method, CVD method) such as a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, and a photochemical vapor deposition method, and the like can be exemplified.

[0165] The thickness of the inorganic oxide layer is not particularly limited, and is preferably 5 nm or more and 500 nm or less. By making the thickness of the inorganic oxide layer 5 nm or more, the inorganic oxide layer becomes uniform, and it is possible to impart sufficient gas barrier properties to the film for wavelength conversion sheet. The inorganic oxide layer is more preferably 8 nm or more, and further preferably 10 nm or more, in view of gas barrier properties. In addition, by making the thickness of the inorganic oxide layer 500 nm or less, it is possible to sufficiently impart flexibility to the inorganic oxide layer, and it is possible to reduce the occurrence of damage or cracking in each inorganic oxide layer. The inorganic oxide layer is more preferably 100 nm or less, and further preferably 50 nm or less, and particularly preferably 20 nm or less, in view of transparency and productivity, and the like. In the case where a plurality of inorganic oxide layers are provided, each inorganic oxide layer is preferably in the above-described thickness range.

[0166] <coating layer>

[0167] The coating layer is a layer that prevents various damages due to secondary processes and imparts high gas barrier properties to the wavelength conversion sheet. In addition, in the case where an inorganic oxide layer is located between the base material layer and the coating layer, it is possible to reduce the occurrence of damages and cracks in the inorganic oxide layer. Furthermore, in the case where the coating layer is in contact with the primer layer, it is possible to make the adhesion of the primer layer and the barrier layer of the present disclosure good.

[0168] The coating layer is a layer that contains at least a water-soluble polymer. As the coating layer, there are a coating layer formed by applying a coating agent containing an organic component such as a water-soluble polymer, and a coating layer formed by applying a coating agent containing an inorganic oxide component and an organic component such as a water-soluble polymer.

[0169] As the water-soluble polymer, polyvinyl alcohol, polyvinylpyrrolidone, and ethylene-vinyl alcohol copolymer, and the like can be given, and from the viewpoint of barrier properties, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferable, and polyvinyl alcohol is more preferable. That is, the coating layer preferably contains one or more selected from the group consisting of polyvinyl alcohol and ethylene-vinyl alcohol copolymer, and more preferably contains polyvinyl alcohol.

[0170] The inorganic oxide component contains at least one or more metal alkoxide-based compounds. As the metal alkoxide-based compound, metal alkoxide, metal alkoxide hydrolysate, and metal alkoxide polymer can be given. The metal alkoxide hydrolysate and the metal alkoxide polymer are obtained by hydrolyzing a metal alkoxide by a sol-gel method.

[0171] The metal alkoxide is a compound represented by the general formula of M(OR) n . In the formula, M represents a metal such as Si, Ti, Al, and Zr, and R represents an alkyl group such as a methyl group and an ethyl group. As specific examples of the metal alkoxide, tetramethoxysilane, tetraethoxysilane, and isopropoxyaluminum, and the like can be given.

[0172] As the inorganic oxide component, tin chloride can be further contained.

[0173] In the case where the coating layer contains a water-soluble polymer and a metal alkoxide-based compound, the content of the water-soluble polymer is preferably 5 parts by mass or more and 500 parts by mass or less, more preferably 7 parts by mass or more and 100 parts by mass or less, and further preferably 8 parts by mass or more and 50 parts by mass or less, with respect to 100 parts by mass of the total amount of the metal alkoxide-based compound.

[0174] The coating agent can contain additives such as a silane coupling agent, a curing agent, and a dispersant, and a solvent.

[0175] As the solvent, a water / alcohol mixed solution is preferable.

[0176] As the silane coupling agent, a known organic alkoxysilane containing an organic reactive group can be used. In the present disclosure, an organic alkoxysilane having an epoxy group is particularly preferable, and examples thereof include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and the like. One or two or more kinds of the silane coupling agents described above can be used in admixture. In the present disclosure, the amount of the silane coupling agent described above is preferably 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the alkoxysilane described above.

[0177] The thickness of the coating layer is not particularly limited, and is preferably 100 nm or more and 500 nm or less. By making the thickness of the coating layer 100 nm or more, the wavelength conversion sheet film can be given sufficient gas barrier properties. The coating layer is more preferably 120 nm or more, and further preferably 150 nm or more, in view of the gas barrier properties. In addition, by making the thickness of the coating layer 500 nm or less, sufficient transparency can be ensured. The coating layer is more preferably 300 nm or less, and further preferably 200 nm or less, in view of the transparency and productivity, and the like. In the case where a plurality of coating layers are provided, each of the coating layers is preferably in the above-described thickness range.

[0178] <metal phosphoric acid reactant layer>

[0179] As the layer containing a composition containing a metal oxide and a phosphorus compound (metal phosphoric acid reactant layer), for example, the layer described in International Publication WO2011 / 122036 can be given. As the above-described metal, aluminum is preferable.

[0180] The thickness of the metal phosphoric acid reactant layer is not particularly limited, and is preferably 100 nm or more and 2,000 nm or less. By making the thickness of the metal phosphoric acid reactant layer 100 nm or more, the wavelength conversion sheet film can be given sufficient gas barrier properties. The metal phosphoric acid reactant layer is more preferably 200 nm or more, and further preferably 300 nm or more, in view of the gas barrier properties. In addition, by making the thickness of the metal phosphoric acid reactant layer 2,000 nm or less, film breakage at the time of film formation can be suppressed. The metal phosphoric acid reactant layer is more preferably 1,000 nm or less, and further preferably 900 nm or less, in view of the bending resistance, and the like.

[0181] [diffusion layer]

[0182] The diffusion layer is a layer provided to reduce the anisotropy of the light exit angle distribution and to prevent adhesion, and is an arbitrarily provided layer in the present disclosure.

[0183] The diffusion layer contains a binder resin and a filler. By burying the filler itself in the binder resin, and further, by exposing at least a part of the filler from the binder resin to the layer surface side to impart a concavo-convex shape to the diffusion layer surface, a reduction effect of anisotropy of the light exit angle distribution can be obtained.

[0184] Further, by making the diffusion layer surface a concavo-convex shape, in the manufacturing process of the wavelength conversion sheet-use film or the wavelength conversion sheet, even if the wavelength conversion sheet-use film or the wavelength conversion sheet are in contact with each other, it has an effect of preventing adhesion. For example, in the case of manufacturing the wavelength conversion sheet-use film or the wavelength conversion sheet in a roll-up manner, the handling of the wavelength conversion sheet-use film or the wavelength conversion sheet becomes easy, and the surface damage can be suppressed. In addition, when a display device is manufactured, it also has an effect of preventing adhesion of the light guide plate or the diffusion plate to the wavelength conversion sheet, and also functions to suppress the generation of damage caused by the rubbing of the light guide plate or the diffusion plate to the wavelength conversion sheet, and to reduce the generation of appearance defects of the display device.

[0185] The binder resin of the diffusion layer is not particularly limited as long as it satisfies the required specifications of the wavelength conversion sheet-use film and the wavelength conversion sheet. For example, an acrylic resin, an epoxy resin, a urethane resin, a polyester-based resin, a polyester acrylate-based resin, a polyurethane acrylate-based resin, an acrylic polyurethane-based resin, an epoxy acrylate-based resin, or the like can be used. From the viewpoint of having high hardness, the binder resin is preferably an acrylic resin.

[0186] From the viewpoint of the optical properties required of the wavelength conversion sheet-use film and the wavelength conversion sheet, the filler is preferably a resin filler. As the resin used for the filler, for example, an acrylic resin, a polystyrene-based resin, or the like can be mentioned. From the viewpoint of improving the damage resistance of the diffusion layer, an acrylic resin filler is particularly preferred. The acrylic resin here refers to a polymer containing at least one ethylenically unsaturated monomer having a carboxyl group or a carboxylate group selected from the group consisting of methacrylic acid, acrylic acid, methacrylate, and acrylate as a monomer component.

[0187] The refractive index difference between the refractive index of the filler and the refractive index of the resin binder is preferably 0.5 or less, more preferably 0.3 or less, and further preferably 0.1 or less.

[0188] The average particle diameter of the filler is preferably 1 μm or more and 50 μm or less, and more preferably 1.5 μm or more and 10 μm or less. By making the average particle diameter of the filler 1 μm or more, at least a part of the filler is more exposed from the surface of the diffusion layer, and a moderate light diffusivity can be imparted, and adhesion can be more effectively suppressed. By making the average particle diameter of the filler 50 μm or less, the filler is less likely to be detached from the diffusion layer, and the reduction of the function of the diffusion layer and the damage caused by the detached filler can be suppressed.

[0189] Note that in the present disclosure, the average particle diameter refers to the volume average d50 in particle size distribution measurement using a laser diffraction method.

[0190] The content of the filler is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, with respect to the total amount of the diffusion layer. By being 5% by mass or more, a moderate light diffusivity can be imparted, and adhesion can be effectively prevented. By being 50% by mass or less, the optical properties required of the film for wavelength conversion sheet and the wavelength conversion sheet can be easily satisfied, and furthermore, the film formability of the diffusion layer is also good.

[0191] The diffusion layer can arbitrarily contain, as needed, a stabilizer, a curing agent, a crosslinking agent, a lubricant, an ultraviolet absorber, other additives, and the like.

[0192] The thickness of the diffusion layer is not particularly limited, and can be appropriately set in accordance with the average particle diameter of the filler, the required specifications of the film for wavelength conversion sheet and the wavelength conversion sheet, and the like. For example, the thickness of the diffusion layer is preferably 1.0 μm or more and 50.0 μm or less, more preferably 1.5 μm or more and 10.0 μm or less. Note that the thickness of the diffusion layer refers to the thickness of the resin portion other than the filler in the diffusion layer, and does not include the portion of the filler exposed on the resin. The thickness of the diffusion prevention layer can be measured, for example, by observing the cross section using a scanning electron microscope or the like.

[0193] [Physical properties of the film for wavelength conversion sheet]

[0194] When the film for wavelength conversion sheet of the present disclosure is used as a wavelength conversion sheet, in order to efficiently convert light from a light source, the total light transmittance measured based on JIS K 7361-1:1997 is preferably high. Specifically, the total light transmittance of the film for wavelength conversion sheet of the present disclosure measured based on JIS K 7361-1:1997 is preferably 85% or more, more preferably 90% or more.

[0195] The gas barrier property of the film for wavelength conversion sheet of the present disclosure can be set in accordance with the requirements taking into account the deterioration of the phosphor described later. Specifically, in the case where the phosphor used in the wavelength conversion sheet has a property of easily deteriorating due to oxygen, water vapor, or the like, the film for wavelength conversion sheet preferably has a high gas barrier property. On the other hand, if the phosphor does not easily deteriorate, a high gas barrier property is not required for the film for wavelength conversion sheet.

[0196] The value of the oxygen transmission degree based on JIS K 7129-2:2006 of the film for wavelength conversion sheet is preferably 20 cc / m 2 ·day·atm or less, more preferably 10 cc / m 2 ·day·atm or less, more preferably 10 cc / m 2• 2 cc / m2 / day atm or less, particularly preferably 2 cc / m2 / day 2 • 20 g / m2 / day atm or less. In addition, the value of the water vapor permeability of the film for wavelength conversion sheet based on the JIS K 7129:2008 B method is preferably 20 g / m2 / day 2 • 10 g / m2 / day or less, more preferably 10 g / m2 / day 2 • 5 g / m2 / day or less, further preferably 5 g / m2 / day 2 • 2 g / m2 / day or less, particularly preferably 2 g / m2 / day 2 • 2 g / m2 / day or less.

[0197] The oxygen permeability can be measured, for example, using an oxygen permeability measuring device "OX-TRAN" manufactured by MOCON, Inc. (MOCON method). In addition, the water vapor permeability can be measured, for example, using a water vapor permeability measuring device "PERMATRAN" manufactured by MOCON, Inc. The conditions at the time of measuring the oxygen permeability are 23°C in temperature and 90% in relative humidity. The conditions at the time of measuring the water vapor permeability are 40°C in temperature and 90% in relative humidity.

[0198] [Fluorescent layer]

[0199] The fluorescent layer is a layer for adjusting the emission wavelength of light emitted from the backlight. The fluorescent layer can be formed by laminating an encapsulating resin containing a fluorescent material. For example, it can be formed by applying a mixed solution containing a fluorescent material and an encapsulating resin to the surface of the substrate layer and curing it. One or two or more kinds of fluorescent materials composed of quantum dots are contained in the fluorescent layer.

[0200] The quantum dots that form the fluorescent material are semiconductor particles of a prescribed size that have a quantum confinement effect. When the quantum dots absorb light from an excitation source and reach an energy excited state, they emit energy corresponding to the energy band gap of the quantum dots. By adjusting the size or composition of the quantum dots, the energy band gap can be adjusted, and energy of various levels of wavelength can be obtained. In particular, the quantum dots can produce strong fluorescence in a narrow wavelength band. Therefore, the display device can be illuminated using light of three primary colors that have excellent color purity, and thus a display device having excellent color reproducibility can be produced.

[0201] The quantum dots preferably include quantum dots that emit secondary light of a wavelength corresponding to red, quantum dots that emit secondary light of a wavelength corresponding to green, and combinations thereof. Note that the quantum dots can contain quantum dots other than quantum dots that emit secondary light of a wavelength corresponding to red, quantum dots that emit secondary light of a wavelength corresponding to green

[0202] The core of the quantum dot is a nano-sized particle of a semiconductor, and there is no particular limitation as long as it is a material that produces a quantum confinement effect (quantum size effect). As the quantum dot, there can be cited a semiconductor particle that restricts the color of light emission by the particle diameter itself and a semiconductor particle with a dopant.

[0203] As the material that becomes the core, specifically, there can be cited a semiconductor compound or a semiconductor crystal of a Group II-VI semiconductor compound such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe; a Group III-V semiconductor compound such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs, and TiSb; a Group IV semiconductor such as Si, Ge, and Pb, and the like. In addition, a semiconductor crystal of a semiconductor compound containing three or more kinds of elements such as InGaP can also be used.

[0204] Further, as the quantum dot composed of a semiconductor particle with a dopant, there can also be used a semiconductor crystal in which a cation of a rare earth metal such as Eu 3+ , Tb 3+ , Ag + , Cu + or a cation of a transition metal is doped in the above semiconductor compound.

[0205] As the material that becomes the core of the quantum dot, from the aspects of ease of production, controllability of the particle diameter to obtain light emission in the visible region, and fluorescence quantum yield, a semiconductor crystal of CdS, CdSe, CdTe, InP, InGaP, or the like is preferable.

[0206] The quantum dots can be composed of one semiconductor compound or two or more semiconductor compounds. For example, the quantum dots can have a structure in which a core serving as a light-emitting portion is covered with a protective layer (shell) (core-shell structure). In the case of using quantum dots of the core-shell type, by using a material having a higher band gap than the semiconductor compound forming the core to confine excitons in the core, the light-emitting efficiency of the quantum dots can be improved. As a core-shell structure (core / shell) having such a size relationship of the band gap, for example, CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, CdTe / CdS, InP / ZnS, GaP / ZnS, Si / ZnS, InN / GaN, InP / CdSSe, InP / ZnSeTe, InGaP / ZnSe, InGaP / ZnS, Si / AlP, InP / ZnSTe, InGaP / ZnSTe, InGaP / ZnSSe, and the like can be given.

[0207] To obtain light of a desired wavelength, the size of the quantum dots is appropriately controlled by the material constituting the quantum dots. As the particle diameter of the quantum dots becomes smaller, the band gap increases. That is, as the crystal size becomes smaller, the light emission of the quantum dots shifts to the blue side, that is, the high-energy side.

[0208] Generally, the particle diameter (diameter) of the quantum dots is preferably in the range of 0.5 nm or more and 20 nm or less, and particularly preferably in the range of 1 nm or more and 10 nm or less. Note that the narrower the size distribution of the quantum dots, the clearer the light emission color can be obtained. The particle diameter of the quantum dots is the average value of the particle diameters measured for 20 quantum dots randomly selected by observing the cross section of the phosphor layer using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The particle diameter here is the value of the distance between the straight lines in the combination of the straight lines having the largest distance between the straight lines when the cross section of the quantum dots is sandwiched with two straight lines in parallel.

[0209] The shape of the quantum dots is not particularly limited and can be, for example, spherical, rod-shaped, disc-shaped, or other shapes. Regarding the particle diameter of the quantum dots, when the quantum dots are not spherical, the value of a sphere having the same volume can be used.

[0210] The quantum dots can be covered with a resin.

[0211] The content of the quantum dots is appropriately adjusted depending on the thickness of the phosphor layer, the light recycling rate in the backlight, the target color tone, and the like. If the thickness of the phosphor layer is in the range described later, the content of the quantum dots is preferably 0.01 parts by mass or more and 1.0 parts by mass or less with respect to 100 parts by mass of the encapsulating resin of the phosphor layer.

[0212] As the encapsulating resin of the phosphor layer, a cured product of a thermosetting resin composition, a cured product of an ionizing radiation-curable resin composition can be given. Among these, from the aspect of durability, a cured product of a thermosetting resin composition, a cured product of an ionizing radiation-curable resin composition are preferable, and a cured product of an ionizing radiation-curable resin composition is more preferable.

[0213] The thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition which is cured by heating. As the thermosetting resin, an acrylic resin, a urethane resin, a phenol resin, a urea melamine resin, an epoxy resin, an unsaturated polyester resin, a silicone resin, and the like can be given. These can be used alone, or one or more kinds thereof can be used in combination. In the thermosetting resin composition, a curing agent can be added to these curable resins as necessary.

[0214] The ionizing radiation-curable resin composition is a composition containing a compound having an ionizing radiation-curable functional group (hereinafter also referred to as "ionizing radiation-curable compound").

[0215] As the ionizing radiation-curable functional group, an ethylenic unsaturated bond group such as a (meth)acryloyl group, a vinyl group, an allyl group, and the like, and an epoxy group, an oxetanyl group, and the like can be given, and among these, an ethylenic unsaturated bond group is preferable. Further, among the ethylenic unsaturated bond groups, a (meth)acryloyl group is preferable. Hereinafter, the ionizing radiation-curable compound having a (meth)acryloyl group is referred to as a (meth)acrylate-based compound. That is, the encapsulating resin preferably contains a cured product of a composition containing a (meth)acrylate-based compound.

[0216] Note that, in the present specification, "(meth)acrylate" means methacrylate and acrylate. Further, in the present specification, "ionizing radiation" means ionizing radiation having an energy quantum capable of polymerizing or crosslinking molecules among electromagnetic waves or charged particle beams, and ultraviolet rays (UV) or electron beams (EB) are generally used, but electromagnetic waves such as X-rays, γ-rays, and charged particle beams such as α-rays and ion beams can also be used.

[0217] The ionizing radiation-curable compound can be a monofunctional ionizing radiation-curable compound having only one of the above functional groups, or can be a multifunctional ionizing radiation-curable compound having two or more of the above functional groups, and can also be a mixture of these compounds. Among these, a multifunctional ionizing radiation-curable compound is preferable, and a multifunctional (meth)acrylate-based compound having two or more (meth)acryloyl groups is more preferable. That is, the encapsulating resin preferably contains a cured product of a multifunctional ionizing radiation-curable compound, and more preferably contains a cured product of a multifunctional (meth)acrylate-based compound.

[0218] The polyfunctional (meth)acrylate-based compound can have an alkylene oxide group.

[0219] As the alkylene oxide group, for example, an alkylene oxide group having 2 to 4 carbon atoms is preferable, an alkylene oxide group having 2 or 3 carbon atoms is more preferable, and an alkylene oxide group having 2 carbon atoms is further preferable.

[0220] The polyfunctional (meth)acrylate-based compound having an alkylene oxide group can be a polyfunctional (meth)acrylate-based compound having a polyalkylene oxide group including a plurality of alkylene oxide groups.

[0221] In the case where the polyfunctional (meth)acrylate-based compound has an alkylene oxide group, the number of alkylene oxide groups in one molecule is preferably 2 to 30, more preferably 2 to 20, further preferably 3 to 10, and more further preferably 3 to 5.

[0222] In the case where the polyfunctional (meth)acrylate-based compound has an alkylene oxide group, it is preferable to have a bisphenol structure. Thereby, there is a tendency that the heat resistance of the cured product is improved. As the bisphenol structure, for example, a bisphenol A structure and a bisphenol F structure can be given, of which the bisphenol A structure is preferable.

[0223] As the polyfunctional (meth)acrylate-based compound having an alkylene oxide group, an ethoxylated bisphenol A type di(meth)acrylate, a propoxylated bisphenol A type di(meth)acrylate, and a propoxylated ethoxylated bisphenol A type di(meth)acrylate are preferable, and the ethoxylated bisphenol A type di(meth)acrylate is more preferable.

[0224] In addition, the ionizing radiation-curable compound can be a monomer, can be an oligomer, can be a low-molecular-weight polymer, or can be a mixture of these.

[0225] The thermosetting resin composition and the ionizing radiation-curable resin composition preferably contain a thiol compound.

[0226] The thiol compound is a compound having one or more units represented by R-SH (R is an organic group). In the present disclosure, a compound having one unit represented by R-SH is referred to as a monofunctional thiol compound, and a compound having two or more units represented by R-SH is referred to as a polyfunctional thiol compound.

[0227] The thiol compound can be a monofunctional thiol compound, but in order to improve the strength of the phosphor layer, a polyfunctional thiol compound is preferable. In addition, among the polyfunctional thiol compounds, a trifunctional thiol compound or a tetrafunctional thiol compound is more preferable.

[0228] The thiol compound reacts with a compound having a radically polymerizable functional group in the presence of a radically polymerizing initiator, in the following formula (thiol-ene reaction). The thiol-ene reaction can suppress polymerization shrinkage, and therefore can moderate stress generated at the time of curing of the phosphor layer, as a result of which it is preferable from the viewpoint of easily further improving the interlayer adhesion of the wavelength conversion sheet. In addition, it is preferable to obtain a cured product by the thiol-ene reaction from the viewpoint of easily improving the heat resistance. Furthermore, the refractive index of the thiol compound (about 1.53) is higher than the refractive index of the polyfunctional (meth)acrylate-based compound (about 1.45), and therefore it is possible to improve the degree of freedom in adjusting the refractive index of the phosphor layer.

[0229] Note that the following reaction is an example of the reaction of a monofunctional thiol compound with a compound having one radically polymerizable functional group. It is considered that a reaction product of a polyfunctional thiol compound and a compound having two or more radically polymerizable functional groups easily forms a dendrimer structure. Furthermore, in the case where a dendrimer structure is formed, it is considered that the softness of the phosphor layer increases, and the phosphor layer itself easily exhibits excellent stress relaxation properties. As the radically polymerizable functional group, a group containing an ethylenic unsaturated bond such as a (meth)acryloyl group, a vinyl group, and an allyl group can be given.

[0230] [Chemical Formula 1]

[0231]

[0232] [In the formula, R 1 and R 2 are organic groups.]

[0233] As specific examples of the monofunctional thiol compound, hexanethiol, 1-heptanethiol, 1-octanethiol, 1-nonanethiol, 1-decanethiol, 3-mercaptopropionic acid, methyl 3-mercaptopropionate, methoxybutyl 3-mercaptopropionate, octyl 3-mercaptopropionate, tridecyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, n-octyl 3-mercaptopropionate, and the like can be given.

[0234] As specific examples of the polyfunctional mercapto compound, ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), 1,2-propanediol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptobutyrate), 1,4-butanediol bis(3-mercaptopropionate), 1,4-butanediol bis(3-mercaptobutyrate), 1,8-octanediol bis(3-mercaptopropionate), 1,8-octanediol bis(3-mercaptobutyrate), hexanediol bismercaptoacetate, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), trimethylolpropane bismercaptoacetate, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trishydroxyethylisocyanurate tris(3-mercaptobutyrate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), pentaerythritol tetra(3-mercaptoisobutyrate), pentaerythritol tetra(2-mercaptoisobutyrate), dipentaerythritol hexa(3-mercaptopropionate), dipentaerythritol hexa(2-mercaptopropionate), dipentaerythritol hexa(3-mercaptobutyrate), dipentaerythritol hexa(3-mercaptoisobutyrate), dipentaerythritol hexa(2-mercaptoisobutyrate), pentaerythritol tetramercaptoacetate, dipentaerythritol hexamercaptoacetate, and the like can be given.

[0235] In the ionizing radiation-curable resin composition (or the thermosetting resin composition), the mass ratio of the ionizing radiation-curable compound (or the thermosetting resin) to the mercapto compound is preferably 80:20 to 35:65, and more preferably 70:30 to 40:60.

[0236] In the case where the ionizing radiation-curable compound is an ultraviolet-curable compound, the ionizing radiation-curable composition preferably contains an additive such as a photopolymerization initiator, a photopolymerization accelerator, or the like.

[0237] As the photopolymerization initiator, a phosphorus-based photopolymerization initiator can be used. As the phosphoric acid-based photopolymerization initiator, Omnirad 819 (manufactured by IGM Resins B.V.), Omnirad TPO H (manufactured by IGM Resins B.V.), and the like can be given.

[0238] The phosphor layer can contain an internal diffusion particle.

[0239] The inner diffusion particles can use either of organic particles and inorganic particles. As the organic particles, particles composed of polymethyl methacrylate, acrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone resin, fluorine-based resin, and polyester, etc. can be given. As the inorganic particles, particles composed of silica, alumina, zirconia, and titania, etc. can be given.

[0240] The shape of the inner diffusion particles can be given as a spherical shape, a disc shape, a rugby ball shape, an amorphous shape, etc. In addition, the inner diffusion particles can be any one of a hollow particle, a porous particle, and a solid particle.

[0241] The content of the inner diffusion particles is preferably 1 part by mass or more and 40 parts by mass or less, more preferably 3 parts by mass or more and 30 parts by mass or less, with respect to 100 parts by mass of the encapsulating resin.

[0242] The average particle diameter of the inner diffusion particles is preferably 1 μm or more and 7 μm or less, more preferably 1 μm or more and 3 μm or less. The average particle diameter of the inner diffusion particles is an average value of the particle diameters of 20 inner diffusion particles randomly selected, measured by observing a cross section of the phosphor layer using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Note that the particle diameter is a value obtained by measuring the distance between two straight lines in a combination of two straight lines having the largest distance between them when the cross section of the quantum dots is sandwiched by the two straight lines in parallel.

[0243] The thickness of the phosphor layer is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, further preferably 30 μm or more and 130 μm or less.

[0244] The refractive index n of the phosphor layer Z is preferably 1.40 or more and 1.55 or less, more preferably 1.43 or more and 1.52 or less, further preferably 1.46 or more and 1.50 or less.

[0245] The refractive index n of the phosphor layer Z is substantially governed by the refractive index of the encapsulating resin. This is because the content of the quantum dots in the phosphor layer is small, and in addition, even if the inner diffusion agent is added, the particle diameter of the inner diffusion agent is larger than the wavelength of light, and has no influence on the refractive index of the layer.

[0246] [Method for manufacturing wavelength conversion sheet]

[0247] The method for manufacturing the wavelength conversion sheet of the present disclosure includes: (1) a step of manufacturing a film for wavelength conversion sheet; and (2) a step of bringing the film for wavelength conversion sheet into contact with a phosphor layer.

[0248] The wavelength conversion sheet film of the present disclosure is manufactured, for example, by the following procedure.

[0249] (1-1) Barrier layer forming step

[0250] A barrier layer is formed on one surface of the substrate layer (or the first substrate). Note that the barrier layer forming step can be omitted.

[0251] As shown in Figure 1 , in the case where the coating layer and the inorganic oxide layer are used as the barrier layer, the inorganic oxide layer is first formed on the substrate layer (or the first substrate), and the coating layer is formed on the inorganic oxide layer.

[0252] Note that the surface treatment described above can be performed in advance on the surface of the substrate layer (or the first substrate) on which the barrier layer is formed, or a base layer can be formed.

[0253] The inorganic oxide layer can be formed by evaporation or a sol-gel method. Methods of evaporating the inorganic oxide include physical vapor deposition methods (PVD methods) such as vacuum evaporation, sputtering, and ion plating, or chemical vapor deposition methods (CVD methods) such as plasma CVD, thermal CVD, and photo CVD.

[0254] The coating layer can be formed by applying a coating agent containing at least an organic component such as a water-soluble polymer and curing it by heating. The coating agent is prepared by adding a solvent or the like in a manner to obtain the desired gas barrier property, thickness, viscosity, and the like. The coating method of the coating agent includes roll coating, gravure coating, blade coating, dip coating, spray coating, and other coating methods.

[0255] The metal phosphoric reaction product layer can be formed by the method described in International Publication WO 2011 / 122036.

[0256] (1-2) Primer layer forming step

[0257] A primer layer is formed on the substrate layer or the barrier layer. The primer layer can be formed by applying a coating agent containing a resin composition including the polyurethane-based resin described above and curing it by heating. The coating agent is prepared by adding a solvent or the like in a manner to obtain the thickness, viscosity, and the like. The coating method of the coating agent includes roll coating, gravure coating, blade coating, dip coating, spray coating, and other coating methods. The heating temperature is preferably in the range of 50°C or higher and 180°C or lower.

[0258] As shown in Figure 1In the case where the base material layer is configured by stacking a plurality of base material layers, the manufacturing method of the wavelength conversion sheet film of the present disclosure has, after the (1-2) primer layer forming step, a (1-3) bonding step.

[0259] (1-3) Bonding step

[0260] In the bonding step, the surface of the first base material on the opposite side of the barrier layer and the second base material are stacked via the adhesive layer.

[0261] Specifically, the adhesive described above is applied to the surface of the first base material, the second base material is overlaid, and the adhesive layer is cured. Alternatively, after applying a coating agent containing a cross-linking agent and a resin to the surface of the first base material, the second base material is overlaid, and the coating agent is cross-linked by heat or the like. The method of applying the adhesive or the coating agent can be carried out by roll coating, gravure coating, blade coating, dip coating, spraying, other coating methods, or printing methods, and the like.

[0262] Alternatively, the adhesive layer can also be formed by extrusion lamination, in which a molten thermoplastic resin is caused to flow between the first base material and the second base material, and then cooled.

[0263] Note that, in the case where a diffusion layer is provided as shown in Figure 2 In the case where a diffusion layer is provided as shown in

[0264] Specifically, a coating agent containing a resin, a filler, a solvent, and the like can be applied to the surface of the base material layer or the second base material on the opposite side of the surface on which the barrier layer is provided, and cured to form the diffusion layer. The method of applying the coating agent can be roll coating, gravure coating, blade coating, dip coating, spraying, other coating methods, or the like.

[0265] (2) Step of bringing the phosphor layer into contact with the wavelength conversion sheet film

[0266] In this step, the primer layer of the wavelength conversion sheet film is brought into contact with the phosphor layer. Hereinafter, as an example, a method of manufacturing a wavelength conversion sheet configured such that the wavelength conversion sheet film sandwiches the phosphor layer will be described.

[0267] Specifically, a mixed solution containing a phosphor and an encapsulating resin (a resin composition as a precursor of the phosphor layer) is prepared. In the present disclosure, as a solvent of the mixed solution, a solvent that does not easily attack the components of the resin composition that constitutes the primer layer is used. For example, in the case where the primer layer contains a cured product of a urethane-based resin composition, a hydrophobic solvent such as ethyl acetate, toluene, methyl ethyl ketone, or the like is used.

[0268] The above-described mixed solution is applied to the surface of the primer layer of the wavelength conversion sheet film prepared in (1), and a coating film is formed. The method of applying the mixed solution can be roll coating, gravure coating, blade coating, dip coating, spraying, other coating methods, or the like.

[0269] Then, the surface of the phosphor layer on the opposite side is brought into contact with the primer layer of the film for another wavelength conversion sheet prepared in (1). Then, the coated film is cured by heat, ionizing radiation, or the like, to obtain a wavelength conversion sheet.

[0270] [Backlight]

[0271] The backlight of the present disclosure has at least one light source that emits primary light, an optical sheet for guiding or diffusing light disposed adjacent to the light source, and a wavelength conversion sheet (quantum dot sheet) disposed on the light exit side of the optical sheet, wherein the wavelength conversion sheet is the wavelength conversion sheet of the present disclosure described above.

[0272] As the backlight 200 of the present disclosure, Figure 3 the edge light type backlight shown in Figure 2 the direct type backlight shown in

[0273] Figure 3 The optical sheet 120 used in the edge light type backlight 201 is an optical member for guiding the primary light emitted by the light source 110, and is a so-called light guide plate 121. The light guide plate 121 is composed of a substantially flat plate shape formed in such a manner that at least one face is a light incident face and one face substantially orthogonal thereto is a light exit face, for example.

[0274] The light guide plate is mainly composed of a base resin selected from high transparent resins such as polymethyl methacrylate. The light guide plate can be added with resin particles having a different refractive index from the base resin as needed. Each face of the light guide plate can be a complex surface shape instead of a uniform plane, and can be provided with a dot pattern or the like.

[0275] ​ The optical sheet 120 used in the direct type backlight 202 is an optical member (light diffusing material 122) having light diffusivity for making the pattern of the light source 110 difficult to see. As the light diffusing material 122, a milky white resin plate having a thickness of about 1 mm to 3 mm, for example, can be cited.

[0276] In the edge light type and direct type backlights, in addition to the light source, the optical sheet, and the wavelength conversion sheet described above, one or more members selected from a reflecting plate, a light diffusing film, a prism sheet, a brightness enhancement film (BEF), a reflective polarizing film (DBEF), and the like can be provided as needed. The reflecting plate is disposed on the side of the optical sheet opposite to the light exit face side. The light diffusing film, the prism sheet, the brightness enhancement film, and the reflective polarizing film are disposed on the light exit face side of the optical sheet. By being provided with one or more members selected from a reflecting plate, a light diffusing film, a prism sheet, a brightness enhancement film, and a reflective polarizing film, and the like, a backlight having an excellent balance of front surface brightness, viewing angle, and the like can be produced.

[0277] In the edge light type and direct light type backlight, the light source 110 is a light emitting body that emits primary light, and a light emitting body that emits primary light of a wavelength corresponding to blue is preferably used. The peak wavelength of the primary light of a wavelength corresponding to blue is preferably in the range of 380 nm to 480 nm. The peak wavelength is more preferably 450 nm ± 7 nm, more preferably 450 nm ± 5 nm, more preferably 450 nm ± 3 nm, and more preferably 450 nm ± 1 nm.

[0278] As the light source 110, from the viewpoint of enabling the device in which the backlight is provided to be simplified and downsized, a LED light source is preferable, and a blue monochromatic LED light source is more preferable. Alternatively, a blue monochromatic LED light source can be coated with a red phosphor to form a light source that emits light in blue and red. The light source 110 is at least one, and from the viewpoint of emitting sufficient primary light, two or more are preferable.

[0279] [Display device]

[0280] As the display device, a liquid crystal display device can be given as an example. The liquid crystal display device is provided with a backlight and a liquid crystal panel. The backlight is the above-described backlight of the present disclosure.

[0281] The liquid crystal panel is not particularly limited, and a liquid crystal panel commonly used for liquid crystal display devices can be used. For example, a liquid crystal panel having a general structure in which a liquid crystal layer is sandwiched by glass plates can be used, and specifically, a liquid crystal panel of a display mode such as TN, STN, VA, IPS, and OCB can be used.

[0282] The liquid crystal display device is further provided with a polarizing plate and a color filter, and the like. The polarizing plate and the color filter can use common substances.

[0283] The wavelength conversion sheet of the present disclosure is particularly excellent in adhesion between the wavelength conversion sheet film and the phosphor layer. Therefore, in the case where the wavelength conversion sheet of the present disclosure is applied to a display device (liquid crystal display device), deterioration of the phosphor layer due to intrusion of water vapor or oxygen from the outside environment can be effectively suppressed. As a result, a display device provided with a backlight excellent in environmental stability can be produced.

[0284] As the use of the display device of the present disclosure, there is no particular limitation, and it is particularly preferable to be used for small electronic devices such as televisions, smartphones, tablet computers, and the like.

[0285] Examples

[0286] Next, the present application will be described in more detail by examples, but the present application is not limited to any of the examples.

[0287] 1. Evaluation, measurement

[0288] The following measurements and evaluations were performed on the wavelength conversion sheet produced by the following production method. The results are shown in Table 1. Note that the atmosphere at the time of each measurement and evaluation was 23 ± 5°C, 40 to 65% RH, unless otherwise specified, and unless the test was performed under a specific environment, the measurement and evaluation were performed after exposing the sample to the above atmosphere for 30 minutes or more before starting the measurement and evaluation.

[0289] 1-1. XPS analysis

[0290] A test piece of 25 mm x 150 mm was cut out from the wavelength conversion sheet of the examples and comparative examples. The test piece was taken from an area inside 1 cm from the end of the wavelength conversion sheet. The two end portions of the short side of the test piece were held and peeled off at an angle of about 90 degrees.

[0291] For the two test pieces after peeling, samples for XPS analysis were taken separately. For the samples, the X-ray photoelectron spectrum of the peeled surface was measured using an X-ray photoelectron spectrometer (ESCA 3400 manufactured by Shimadzu Corporation). The measurement conditions are described below. The elements of the peeled surface of each test piece were identified by full-spectrum scanning spectroscopy. In a case where nitrogen was detected on the peeled surface of one test piece and nitrogen was not detected on the peeled surface of the other test piece, it was determined that the interface between the primer layer and the phosphor layer was properly peeled off, and the subsequent analysis was performed. The test piece for which nitrogen was not detected was a wavelength conversion sheet film having a phosphor layer laminated, and the peeled surface was specified as the surface of the phosphor layer. The test piece for which nitrogen was detected was a wavelength conversion sheet film alone, and the peeled surface was specified as the surface of the primer layer.

[0292] For the test piece on the primer layer side and the test piece on the phosphor layer side, the proportion of the detected elements was calculated using narrow spectrum.

[0293] Then, the etching of the surface after measurement was performed under the conditions described below, and a new measurement surface was exposed. For the exposed measurement surface, the X-ray photoelectron spectrum was measured under the same conditions, and the proportion of each element was calculated. Specifically, for each narrow spectrum of C1s, N1s, O1s, Al2p, Si2p, and S2p, the background was subtracted using the analysis software (Vision Processing) attached to the device by the Shirley method, and the integral intensity (area) of the peak of each element was obtained. Using the obtained integral intensity (area), the proportion (atomic %) of each element was calculated.

[0294] For the piece on the primer layer side and the piece on the phosphor layer side, etching, measurement, and calculation of the proportion of elements were repeated separately, and the depth distribution of the elements contained in the primer layer and the phosphor layer was obtained.

[0295] <Measurement conditions for X-ray photoelectron spectroscopy>

[0296] Apparatus: ESCA 3400 manufactured by Shimadzu Corporation

[0297] X-ray source: MgKα (hν = 1253.6 eV)

[0298] Emission current: 20 mA

[0299] Accelerating voltage: 10 kV

[0300] Photoelectron take-in angle: 90°

[0301] Measurement area: 6 mmφ

[0302] Charge neutralization: Not performed

[0303] Resolution: Low

[0304] Scan control: B.E.

[0305] Peak shift correction: In the C1s peak, correction was performed so that the peak of C-C would be 285.0 eV

[0306] [Etching conditions]

[0307] Apparatus: X-ray photoelectron spectrometer attached with ion gun

[0308] Ion species: Ar + (Ar monatomic ion)

[0309] Pressure of Ar gas introduction: 2.0 x 10 -2 Pa

[0310] Emission current: 30 mA (measurement on the primer layer side in Example 1), 20 mA (other measurements)

[0311] Accelerating voltage: 0.3 kV, 0.2 kV (measurement on the primer layer side in Example 1) (other measurements)

[0312] 1-2. Initial Adhesion Evaluation

[0313] A test piece of 25 mm x 150 mm was cut out from the wavelength conversion sheet of the examples and comparative examples. The test piece was collected from any 3 places, excluding the area within 1 cm from the end of the wavelength conversion sheet. Using a table material tester (STA-1150, manufactured by Takemoto Scientific Instruments Co., Ltd.), a peeling test was performed under the conditions of a temperature environment of 23°C, a tensile speed of 300 mm / minute, a peeling direction of 180°, and a distance between grips of 15 mm, and the peeling strength between the primer layer and the phosphor layer was measured for each test piece. The average of the peeling strengths obtained was taken as the initial (before the high-temperature high-humidity test) peeling strength.

[0314] 1-3. Evaluation of Adhesion over Time

[0315] The wavelength conversion sheet of the example and the comparative example was put into a constant temperature and humidity tank adjusted to 60°C 90% RH. After 500 hours, the wavelength conversion sheet was taken out of the constant temperature and humidity tank.

[0316] For the taken-out wavelength conversion sheet, the peel strength of each test piece was measured according to the procedure of 1-2 above. The test piece was collected from any 3 places except for the area within 1 cm from the end of the wavelength conversion sheet. The average of the peel strength of the test pieces obtained was taken as the peel strength after each elapsed time.

[0317] 2. Preparation of a sample

[0318] <Example 1>

[0319] As the first substrate, an inorganic oxide layer was formed by vacuum deposition of an aluminum oxide thin film (AIOx, target thickness: 8 nm) on a PET film (thickness: 12 μm).

[0320] While being cooled to 10°C, tetraethoxysilane was mixed in a solution (pH 2.2) mixed with water, isopropyl alcohol, and 0.5 N hydrochloric acid to prepare a solution A. In addition, a solution B mixed with polyvinyl alcohol having a saponification value of 99% or more, isopropyl alcohol was prepared. Solution A and solution B were mixed to prepare a coating liquid for forming a coating layer (solid content: 5%).

[0321] Next, the coating liquid for forming a coating layer was applied on the inorganic oxide layer by gravure printing, and heat-treated at 180°C for 60 seconds to form a coating layer having a thickness of 180 nm.

[0322] Next, a coating liquid 1 for forming a primer layer of the following formulation was prepared. The NCO / OH ratio of the coating liquid 1 for forming a primer layer was 3.0.

[0323] <Coating liquid 1 for forming a primer layer>

[0324] • Polyester polyurethane polyol (hydroxyl value: 5.0 mgKOH / g, solid content: 30%) 50 parts by mass

[0325] • Isocyanate (mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10 mass%) 5 parts by mass

[0326] • Polyester (Tg: 70°C) 20 parts by mass

[0327] • Silane coupling agent (3-methacryloyloxypropyltrimethoxysilane) 1 part by mass

[0328] • Silica powder (average particle diameter 3 μm) 0.5 parts by mass

[0329] • Butylated hydroxytoluene (BHT) 1 part by mass

[0330] • Solvent (methyl ethyl ketone) 50 parts by mass

[0331] Next, the primer layer-forming coating liquid 1 described above was applied onto the coating layer. The application amount of the coating liquid was 0.5 g / m 2 . Then, drying was performed at 80°C for 60 seconds to form a primer layer having a thickness of 0.4 μm (400 nm).

[0332] On the surface of the first substrate opposite to the surface on which the inorganic oxide layer and the primer layer were formed, a urethane-based adhesive (Rock Paint Co., Ltd., trade name "RU-004, H-1") was applied by gravure printing, and dried to form an adhesive layer having a thickness of 4 μm.

[0333] Next, a PET film (thickness: 100 μm) was arranged as a second substrate on the adhesive layer side of the first substrate, and the first substrate and the second substrate were laminated under conditions of a pressurization of 0.2 MPa and a line speed of 50 m / min to produce a film for a wavelength conversion sheet.

[0334] In a glove box in which nitrogen gas purge was performed in such a manner that the oxygen concentration became 300 ppm or less, a quantum dot (phosphor) and an amino-modified silicone were mixed in the composition ratio shown below, while being subjected to waterless heating at 90°C, and stirred using a magnetic stirrer for 4 hours. Then, filtration was performed using a polypropylene filter having a pore size of 0.2 μm to obtain a CdSe / ZnS core-shell type quantum dot dispersion liquid.

[0335] • Quantum dot 1 (emission peak: 540 nm, manufacturing number: 748056, Sigma-Aldrich Co., Ltd.) 0.9 parts by mass

[0336] • Quantum dot 2 (emission peak: 630 nm, manufacturing number: 790206, Sigma-Aldrich Co., Ltd.) 0.9 parts by mass

[0337] • Amino-modified silicone (Genesee Co., Ltd., model number: GP-344, viscosity: 670 mPa-s) 99 parts by mass

[0338] Using the quantum dot dispersion liquid produced above, a resin composition for forming a phosphor layer of the following formulation was prepared.

[0339] • Multifunctional acrylate compound (ethoxylated bisphenol A diacrylate; trade name "ABE-300" of Shin-Nakamura Chemical Co., Ltd.) 58.11 parts by mass

[0340] • Multifunctional thiol compound (pentaerythritol tetra(3-mercaptopropionate); trade name "PEMP" by SC Organic Chemicals) 38.74 parts by mass

[0341] • Photopolymerization initiator (trade name "Omnirad TPO H" by IGM Resins B.V.) 0.5 parts by mass

[0342] • Quantum dot dispersion liquid 1.61 parts by mass

[0343] • Ethyl acetate 0.79 parts by mass

[0344] • Titanium oxide (trade name "TI-Pure R-706" by Chemours; particle diameter 0.36 μm) 0.25 parts by mass

[0345] On the primer layer of the film for wavelength conversion sheet, the above-described resin composition was applied so as to have a thickness of 100 μm (after drying), to form a phosphor layer.

[0346] The other film for wavelength conversion sheet produced by the above-described steps was stacked on the above-described phosphor layer with the primer layer in contact with the phosphor layer. Then, by UV-curing the encapsulation resin of the phosphor layer, the wavelength conversion sheet of Example 1 was produced.

[0347] <Example 2>

[0348] A primer layer-forming coating liquid 2 of the following formulation was prepared, a primer layer having a thickness of 0.4 μm (400 nm) was made, and, other than this, the wavelength conversion sheet of Example 2 was produced by the same procedure as Example 1. The primer layer-forming coating liquid 2 differed from the primer layer-forming coating liquid 1 in that a polyester having a high glass transition temperature was used. The NCO / OH ratio of the primer layer-forming coating liquid 2 was 3.0.

[0349] <Primer layer-forming coating liquid 2>

[0350] • Polyester polyurethane polyol (hydroxyl value: 5.0 mgKOH / g, solid content: 30%) 50 parts by mass

[0351] • Isocyanate (mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10 mass%) 5 parts by mass

[0352] • Polyester (Tg: 80°C) 20 parts by mass

[0353] • Silane coupling agent (3-methacryloyloxypropyltrimethoxysilane) 1 part by mass

[0354] • Silica powder (average particle diameter 3 μm) 0.5 parts by mass

[0355] • Butylated hydroxytoluene (BHT) 1 part by mass

[0356] • Solvent (methyl ethyl ketone) 50 parts by mass

[0357] <Example 3>

[0358] A coating liquid 3 for primer layer formation of the following formulation was prepared, a primer layer having a thickness of 0.4 μm (400 nm) was formed, and a wavelength conversion sheet of Example 3 was produced under the same conditions as Example 1, except for the above. The coating liquid 3 for primer layer formation differed from the coating liquid 1 for primer layer formation in the amount of the polyester mixed. The NCO / OH ratio of the coating liquid 3 for primer layer formation was 3.0.

[0359] <Coating liquid 3 for primer layer formation>

[0360] • Polyester polyurethane polyol (hydroxyl value: 5.0 mgKOH / g, solid content: 30%) 50 parts by mass

[0361] • Isocyanate (mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10 mass%) 5 parts by mass

[0362] • Polyester (Tg: 70°C) 30 parts by mass

[0363] • Silane coupling agent (3-methacryloyloxypropyltrimethoxysilane) 1 part by mass

[0364] • Silica powder (average particle diameter 3 μm) 0.5 parts by mass

[0365] • Butylated hydroxytoluene (BHT) 1 part by mass

[0366] • Solvent (methyl ethyl ketone) 50 parts by mass

[0367] <Comparative Example 1>

[0368] A wavelength conversion sheet was produced under the same conditions as Example 1, except for the following, using a film having a primer layer having a thickness of 0.3 μm (300 nm) whose formulation was changed to the following.

[0369] • Polyester polyurethane polyol (hydroxyl value: 62 mgKOH / g, solid content 20 mass%) 50 parts by mass

[0370] • Silane coupling agent (3-glycidyloxypropylmethyldimethoxysilane) 1 part by mass

[0371] • Silica filler (average particle diameter 5 μm) 1 part by mass

[0372] • Curing agent (1,6-hexamethylene diisocyanate, solid content 35%) 1 part by mass

[0373] • Solvent (methyl ethyl ketone) 50 parts by mass

[0374] 3. Results

[0375] With respect to the wavelength conversion sheet of Example 1, the proportions of each element in the depth direction of the primer layer are shown in Table 1, and the proportions of each element in the depth direction of the phosphor layer are shown in Table 2. With respect to the wavelength conversion sheet of Example 2, the proportions of each element in the depth direction of the primer layer are shown in Table 3, and the proportions of each element in the depth direction of the phosphor layer are shown in Table 4. With respect to the wavelength conversion sheet of Example 3, the proportions of each element in the depth direction of the primer layer are shown in Table 5, and the proportions of each element in the depth direction of the phosphor layer are shown in Table 6. With respect to the wavelength conversion sheet of Comparative Example 1, the proportions of each element in the depth direction of the primer layer are shown in Table 7, and the proportions of each element in the depth direction of the phosphor layer are shown in Table 8.

[0376] In Tables 1 to 8, elements other than carbon (C), nitrogen (N), oxygen (O), and sulfur (S) are collectively "Others". In the present example, the element X is sulfur. In each table, the proportion of each element is expressed to one decimal place. The unit of the proportion of each element is atom%.

[0377] In Tables 1 to 8, each etching time is expressed as a depth of etching. The depth conversion is performed according to the following procedure. First, a wavelength conversion sheet is prepared as a sample, and an ultrathin section is collected from the cross section of the wavelength conversion sheet using an ultramicrotome and a diamond knife. The ultrathin section is observed using a transmission mode of a scanning electron microscope (SEM, Hitachi High-Technologies SU 8000), and the film thicknesses of the primer layer and the phosphor layer are measured. The measurement is performed at three arbitrary points. For the primer layer and the phosphor layer, the average values of the film thicknesses at the three points are taken as the film thickness of the primer layer and the film thickness of the phosphor layer, respectively. Next, for the sample, the primer layer is exposed from the wavelength conversion sheet by the above method, and XPS analysis is performed by the procedure described in 1-1, and the depth distribution of each element contained in the primer layer is obtained. Here, the etching and the measurement are repeated until a measurement point at which the proportion of each element greatly changes and the proportion of an element (Si) contained in the barrier layer located under the primer layer exceeds 5 at. % is obtained. Then, the etching time at which an inflection point of the proportions of carbon (C), oxygen (O), and silicon (Si) is taken. This etching time is regarded as the interface between the primer layer and the barrier layer (coating layer). The etching speed is calculated from the etching time of the inflection point and the film thickness of the primer layer, and each etching time is converted into a depth using the etching speed. For the phosphor layer, the depth distribution of each element is also obtained by the same procedure as described above. For the primer layer, the etching and the measurement are repeated until nitrogen (N) is detected. The etching time at which an inflection point of the proportion of nitrogen (N) is taken. This etching time is regarded as the interface between the phosphor layer and the primer layer of another wavelength conversion sheet film. The etching speed is calculated from the etching time of the inflection point and the film thickness of the phosphor layer, and each etching time is converted into a depth using the etching speed.

[0378] In each table, the peeling surface on the primer layer side and the peeling surface on the phosphor layer side are taken as depths of 0 nm, respectively. For the phosphor layer side (Tables 2, 4, 6, and 8), the results up to an etching time of 3500 seconds are shown.

[0379] [Table 1]

[0380]

[0381] [Table 2]

[0382]

[0383] [Table 3]

[0384]

[0385] [Table 4]

[0386]

[0387] [Table 5]

[0388]

[0389] [Table 6]

[0390]

[0391] [Table 7]

[0392]

[0393] [Table 8]

[0394]

[0395] First, referring to Tables 2, 4, 6, and 8, the proportion of sulfur is substantially constant in the range of depths 0 nm to 392 nm. The phosphor layer is 100 μm, but the proportion of sulfur does not greatly change in the range of depths 0 nm to 392 nm, and thus it can be said that the proportion of sulfur is substantially constant in the entire phosphor layer. Therefore, in the present embodiment, for Table 2 (Example 1), Table 4 (Example 2), Table 6 (Example 3), and Table 8 (Comparative Example 1), the average value of the proportion of sulfur from depth 0 nm to 392 nm (etching time 0 seconds to 3500 seconds) is calculated, and the value of the average value is regarded as the proportion of sulfur in the phosphor layer (C QD ).

[0396] In Tables 1, 3, 5, and 7, the ratio of the proportion of sulfur in the primer layer to the average value C QD of the proportion of sulfur in the phosphor layer is expressed as C PR / C QD In Tables 1 and 3, C PR / C QD is expressed to two decimal places.

[0397] Note that phosphorus (P) was not detected in the examples and comparative examples.

[0398] In Table 1, the proportions of carbon (C), oxygen (O), and others (including silicon (Si)) greatly change between the measurement point of etching time 1500 seconds and the measurement point of 2000 seconds. According to this result, the etching time of 1750 seconds, which is the intermediate point, is regarded as an inflection point. The film thickness of the primer layer (400 nm) is divided by the etching time of the inflection point, and the etching rate 3 is calculated. Using this etching rate, the etching time is converted into depth. Therefore, in Table 1 (Example 1), the data of the primer layer is between depths 0 nm and 343 nm.

[0399] In Table 3 (Example 2), there is a large change between the measurement point of the etching time of 1500 seconds and the measurement point of 2000 seconds. From this result, the etching time of 1750 seconds of the intermediate point is regarded as an inflection point, and the etching time is converted into a depth as in Example 1. In Example 2, data of the primer layer is between the depth of 0 nm and 343 nm.

[0400] In Table 5 (Example 3), there is a large change between the measurement point of the etching time of 1500 seconds and the measurement point of 2000 seconds. From this result, the etching time of 1750 seconds of the intermediate point is regarded as an inflection point, and the etching time is converted into a depth as in Example 1. In Example 3, data of the primer layer is between the depth of 0 nm and 343 nm.

[0401] In Table 7, the proportions of carbon (C), oxygen (O), and others (including silicon (Si)) change greatly between the measurement point of the etching time of 2500 seconds and the measurement point of 3000 seconds. From this result, the etching time of 2750 seconds of the intermediate point is regarded as an inflection point. The film thickness of the primer layer (300 nm) is divided by the etching time of the inflection point to calculate the etching speed. Using this etching speed, the etching time is converted into a depth. Therefore, in Table 7 (Comparative Example 1), data of the primer layer is between the depth of 0 nm and 273 nm.

[0402] For Tables 1, 3, 5, the average value and the standard deviation of the proportion of sulfur are calculated using data corresponding to the etching time of 0 to 1500 seconds of the primer layer. For Table 7, the average value and the standard deviation of the proportion of sulfur are calculated using data corresponding to the etching time of 0 to 2500 seconds of the primer layer. The coefficient of variation of the proportion of sulfur in the primer layer is calculated from the obtained average value and the standard deviation. In addition, for Tables 2, 4, 6, 8, the average value and the standard deviation of the proportion of sulfur are calculated using data of the etching time of 0 to 3500 seconds. The coefficient of variation of the proportion of sulfur in the phosphor layer is calculated from the obtained average value and the standard deviation. The average value, the standard deviation, and the coefficient of variation of the proportion of sulfur with respect to Example 1 are shown in Table 9. The average value, the standard deviation, and the coefficient of variation of the proportion of sulfur with respect to Example 2 are shown in Table 10. The average value, the standard deviation, and the coefficient of variation of the proportion of sulfur with respect to Example 3 are shown in Table 11. The average value, the standard deviation, and the coefficient of variation of the proportion of sulfur with respect to Comparative Example 1 are shown in Table 12. The average value, the standard deviation, and the coefficient of variation are each indicated to two decimal places.

[0403] [Table 9]

[0404]

[0405] [Table 10]

[0406]

[0407] [Table 11]

[0408]

[0409] [Table 12]

[0410]

[0411] The initial peeling strength (result of initial adhesion) and the peeling strength after the long-term environmental test (result of adhesion over time) of the wavelength conversion sheet of Examples 1 to 3 and Comparative Example 1 are shown in Table 13.

[0412] [Table 13]

[0413]

[0414] As is apparent from Table 1, in the primer layer of Example 1, the proportion of sulfur is also low at a depth of 0 nm (peeling surface, interface with the phosphor layer), and the proportion of sulfur has a tendency to sharply decrease on the inside of a depth of 23 nm.

[0415] In the primer layer of Example 1, the C PR / C QD at a depth of 23 nm was 0.01. The C PR / C QD between depths of 2 nm and 11 nm were 0.06 and 0.05, respectively. In addition, no sulfur was detected in a region of 171 nm and deeper (region close to the barrier layer). From this result, it is understood that in the wavelength conversion sheet of Example 1, the penetration of components in the phosphor layer into the primer layer is suppressed.

[0416] As is apparent from Table 3, in the primer layer of Example 2, the proportion of sulfur is low even at a depth of 0 nm, and the proportion of sulfur has a tendency to sharply decrease on the inside of a depth of 23 nm.

[0417] In the primer layer of Example 2, the C PR / C QD at a depth of 23 nm was 0.02. The C PR / C QD between depths of 2 nm and 12 nm were both 0.05. In addition, no sulfur was detected in a region of 115 nm and deeper. From this result, it is understood that in the wavelength conversion sheet of Example 2, the penetration of components in the phosphor layer into the primer layer is suppressed.

[0418] As is apparent from Table 5, in the primer layer of Example 3, the proportion of sulfur is low even at a depth of 0 nm, and the proportion of sulfur has a tendency to sharply decrease on the inside of a depth of 23 nm.

[0419] In the primer layer of Example 3, the CPR / C QD The value is 0.03. The C value is between 2nm and 11nm. PR / C QD All values ​​were 0.04. Furthermore, no sulfur was detected in the 170 nm region and deeper. This result indicates that, in the wavelength conversion sheet of Example 3, the penetration of components from the phosphor layer into the primer layer was suppressed.

[0420] Referring to Table 7, the proportion of sulfur in the primer layer of Comparative Example 1 is higher not only near the interface with the phosphor layer, but also throughout the entire interior.

[0421] As shown in Table 7, C at a depth of 27 nm PR / C QD Up to 0.29. Additionally, in the region near the barrier layer with a depth between 55nm and 273nm, C... PR / C QD The value also increased.

[0422] This result indicates that in the wavelength conversion sheet of Comparative Example 1, the components in the phosphor layer penetrated into the interior of the primer layer at a high concentration.

[0423] Referring to Table 12, the coefficient of variation of the sulfur ratio in the primer layer of Comparative Example 1 is close to that in the phosphor layer. This indicates that Comparative Example 1 exhibits a smaller deviation in the sulfur ratio along the thickness direction of the primer layer. In contrast, in Examples 1-3 shown in Tables 9-11, the coefficient of variation of the sulfur ratio in the phosphor layer is similar to that of Comparative Example 1, while the coefficient of variation of the sulfur ratio in the primer layer is very high. The coefficient of variation of the sulfur ratio along the thickness direction of the primer layer also indicates that all examples suppressed the penetration of components from the phosphor layer into the primer layer.

[0424] Referring to Table 13, the initial peel strength of the wavelength conversion sheets in both the examples and the comparative examples was 5.0 N. However, after long-term environmental testing, the adhesion of the wavelength conversion sheet in Comparative Example 1 was significantly deteriorated compared to that in Examples 1 to 3.

[0425] Based on the above results, it can be understood that by inhibiting the penetration of components in the phosphor layer into the primer layer, it is possible to suppress degradation after long-term environmental testing.

[0426] Symbol Explanation

[0427] 10 (10a, 10b) Wavelength conversion film

[0428] 20 Substrate layer

[0429] 20-1 First Substrate

[0430] 20-2 Second Substrate

[0431] 22 Adhesive layer

[0432] 30 Primer layer

[0433] 40 Barrier Layers

[0434] 42 First barrier layer

[0435] 44 Second barrier layer

[0436] 50 diffusion layers

[0437] 60 fluorophores

[0438] 100 Wavelength Conversion Plate

[0439] 110 Light Source

[0440] 120 optical plate

[0441] 121 Light Guide Plate

[0442] 122 Diffuser Plate

[0443] 130 reflector

[0444] 140 prism sheet

[0445] 200 backlights

[0446] 201 Edge-lit backlight

[0447] 202 Direct-lit backlight

Claims

1. A wavelength conversion sheet comprising: a phosphor layer including a phosphor, and a wavelength conversion sheet film disposed on at least one surface side of the phosphor layer. The wavelength conversion film is formed by stacking at least a substrate layer and a primer layer, wherein the primer layer is in contact with the phosphor layer. The phosphor layer and the primer layer contain element X. The average proportion of element X in the phosphor layer, obtained by X-ray photoelectron spectroscopy (XPS) in the region extending from the interface between the primer layer and the phosphor layer along the thickness direction of the phosphor layer to 400 nm, is denoted as C. QD The proportion of element X in the primer layer, obtained by X-ray photoelectron spectroscopy at any depth within a region between 20 nm and 40 nm from the interface along the thickness direction of the primer layer, is defined as C. PR At that time, C PR / C QD If C is below 0.10, QD and C PR The unit is atoms.

2. The wavelength conversion plate according to claim 1, wherein, The element X is selected from at least one of sulfur and phosphorus.

3. The wavelength conversion plate according to claim 1 or claim 2, wherein, The element X is sulfur.

4. The wavelength conversion plate according to claim 1 or claim 2, wherein, The coefficient of variation of the proportion of element X in the thickness direction of the primer layer, obtained by X-ray photoelectron spectroscopy, is greater than 0.

60.

5. The wavelength conversion plate according to claim 1 or claim 2, wherein, The primer layer comprises polyurethane resin and polyester resin.

6. The wavelength conversion plate according to claim 5, wherein, The polyurethane resin is a resin obtained by reacting a polyfunctional isocyanate having a (meth)acryloyl group with a hydroxyl-containing compound.

7. The wavelength conversion plate according to claim 6, wherein, The isocyanate group to hydroxyl group molar ratio, i.e. NCO / OH ratio, of the polyurethane resin is 1.1 or higher.

8. The wavelength conversion plate according to claim 5, wherein, The primer layer also contains phenolic antioxidants.

9. The wavelength conversion plate according to claim 1 or claim 2, wherein, A barrier layer is also included between the substrate layer and the primer layer.

10. The wavelength conversion plate according to claim 9, wherein, The barrier layer has a first barrier layer and a second barrier layer, wherein the first barrier layer is an inorganic oxide layer.

11. The wavelength conversion plate according to claim 9, wherein, The substrate layer has a first substrate and a second substrate. The barrier layer and the primer layer are formed on one surface of the first substrate. The second substrate is bonded to the other side of the first substrate through an adhesive layer.

12. The wavelength conversion sheet according to claim 1 or claim 2, further comprising a diffusion layer.

13. A backlight source comprising: at least one light source emitting primary light; an optical plate disposed adjacent to the light source for guiding or diffusing light; and a wavelength conversion sheet disposed on the light emitting side of the optical plate, wherein, The wavelength conversion chip is the wavelength conversion chip described in claim 1 or claim 2.

14. A liquid crystal display device comprising a liquid crystal panel and a backlight as described in claim 13.

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