Wavelength conversion sheet, backlight, and liquid crystal display device

Abstract

The present invention provides a wavelength conversion sheet having excellent adhesion between a phosphor layer and a primer layer even after a long-term environment test. Provided is a wavelength conversion sheet comprising: a phosphor layer including a phosphor; and a wavelength conversion sheet film provided on at least one surface side of the phosphor layer. The wavelength conversion sheet film is formed by laminating at least a base material layer and a primer layer, the primer being in contact with the phosphor layer, and the phosphor layer and the primer layer containing an element X. When the average value of the ratio of the element X in the phosphor layer obtained by X-ray photoelectron spectroscopy in a region from an interface between the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer is represented by CQD (atomic%) and the ratio of the element X in the primer layer obtained by X-ray photoelectron spectroscopy at an arbitrarily defined depth in a region of 20-40 nm in the thickness direction of the primer layer from the interface is represented by CPR(atomic%), CPR / CQD is 0.10 or less.

Description

[Technical Field]

[0001] This disclosure relates to a wavelength conversion sheet, and to a backlight and liquid crystal display device equipped with the wavelength conversion sheet. [Background technology]

[0002] With the development of personal computers, the demand for liquid crystal display devices is increasing. Furthermore, the penetration rate of home LCD televisions has also risen recently, and smartphones and tablet devices are becoming increasingly widespread. Therefore, the market for liquid crystal display devices is poised for further expansion. Liquid crystal display devices generally consist of a color filter, a liquid crystal cell, and a backlight. Furthermore, liquid crystal display devices control the intensity of light through the shutter function of the liquid crystal layer within the liquid crystal cell, and display images by separating the color of each pixel into the three primary colors (R, G, and B) using a color filter.

[0003] Previously, cold cathode fluorescent lamps (CCFLs) were used as the backlight source for liquid crystal displays. However, from the perspective of low power consumption and space saving, the backlight source has been switched from CCFLs to LEDs. LEDs used as backlights are widely employed in the form of white LEDs, which combine blue LEDs with YAG-based yellow phosphors. White LEDs have a broad spectral distribution of emission wavelengths and are therefore called pseudo-white.

[0004] Meanwhile, in recent years, the development of backlights using quantum dot technology has also progressed. Quantum dots are nanometer-sized semiconductor particles. Quantum dots can be tuned across the entire visible spectrum of emission wavelengths due to the quantum confinement effect (quantum size effect), in which electrons and excitons are confined within tiny nanometer-sized crystals. Because quantum dots can generate strong fluorescence in a narrow wavelength band, display devices can be illuminated with light of the three primary colors with excellent color purity. Therefore, backlights using quantum dots can be used to create display devices with superior color reproduction.

[0005] The wavelength conversion sheet used as the backlight light source for this display device has a configuration that combines a phosphor layer, in which nanometer-sized semiconductor phosphor particles are dispersed in a resin layer, a film formed on the surface of the phosphor layer to protect it, and an LED light source. The film has water vapor barrier properties to suppress the degradation of the phosphor layer. For example, Patent Document 1 describes a wavelength conversion sheet in which a barrier film is laminated on a phosphor layer containing phosphors, wherein the barrier film is a barrier layer laminated on one side of a predetermined polyethylene terephthalate film, and a backlight unit using the same has been developed.

[0006] To further suppress the penetration of water vapor into the phosphor layer, attempts have been made to improve the adhesion between the phosphor layer and the barrier film having a barrier layer, as described in, for example, Patent Documents 2 and 3. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2015 / 037733 [Patent Document 2] Japanese Patent Publication No. 2020-19141 [Patent Document 3] Japanese Patent Publication No. 2020-160212 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The wavelength conversion sheets described in Patent Documents 2 and 3 are constructed by laminating a primer layer located on the outermost surface of a barrier film with a phosphor layer in contact with it. When the wavelength conversion sheets described in Patent Documents 2 and 3 are left for a long period of time in a high-temperature, high-humidity environment of 60°C and 90%RH (hereinafter referred to as "long-term environmental test"), delamination occurs between the phosphor layer and the primer layer. This delamination allows oxygen and water vapor to penetrate into the interior of the wavelength conversion sheet, causing the phosphor layer to deteriorate, which is a problem. This disclosure has been made in view of the above-mentioned problems, and aims to provide a wavelength conversion sheet that exhibits excellent adhesion between the phosphor layer and the primer layer even after long-term environmental testing, and a backlight and liquid crystal display device having the wavelength conversion sheet. [Means for solving the problem]

[0009] To address the above issues, this disclosure provides the following solutions. <1> ~ <14> To provide. <1> The device comprises a phosphor layer containing a phosphor and a wavelength conversion sheet film provided on at least one surface side of the phosphor layer, wherein the wavelength conversion sheet film is formed by laminating at least a substrate layer and a primer layer, the primer layer is in contact with the phosphor layer, the phosphor layer and the primer layer contain element X, and 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 between the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer is C QD (atomic%) is defined as the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface, and C PR When (atomic%), C PR / C QD A wavelength conversion sheet that satisfies the condition of 0.10 or less. <2> The element X is at least one selected from sulfur and phosphorus. <1> Wavelength conversion sheet as described. <3> The element X is sulfur. <1> or <2> Wavelength conversion sheet as described. <4> 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 0.60 or greater. <1> ~ <3> A wavelength conversion sheet as described in one of the following. <5> The primer layer comprises a polyurethane resin and a polyester resin. <1> ~ <4> A wavelength conversion sheet as described in one of the following. <6> The polyurethane resin is a resin obtained by the reaction of a polyfunctional isocyanate having a (meth)acrylic group with a hydroxyl group-containing compound. <5> Wavelength conversion sheet as described. <7> The polyurethane resin has a molar ratio of isocyanate groups to hydroxyl groups (NCO / OH ratio) of 1.1 or more. <5> or <6> Wavelength conversion sheet as described. <8> The primer layer further comprises a phenolic antioxidant. <5> ~ <7> A wavelength conversion sheet as described in one of the following. <9> A barrier layer is further included between the substrate layer and the primer layer. <1> ~ <8> A wavelength conversion sheet as described in one of the following. <10> The barrier layer comprises a first barrier layer and a second barrier layer, wherein the first barrier layer is an inorganic oxide layer. <9> Wavelength conversion sheet as described. <11> The substrate layer comprises a first substrate and a second substrate, the barrier layer and the primer layer are formed on one surface of the first substrate, and the second substrate is bonded to the other surface of the first substrate via an adhesive layer. <9> or <10> Wavelength conversion sheet as described. <12> Furthermore, having a diffusion layer, <1> ~ <11> A wavelength conversion sheet as described in one of the following. <13> A backlight comprising at least one light source emitting primary light, an optical plate disposed adjacent to the light source for light guidance or diffusion, and a wavelength conversion sheet disposed on the light-emitting side of the optical plate, wherein the wavelength conversion sheet <1> ~ <12> A backlight that is a wavelength conversion sheet as described in any of the following. <14> <13> A liquid crystal display device comprising a backlight and a liquid crystal panel as described above. [Effects of the Invention]

[0010] According to this disclosure, a wavelength conversion sheet can be obtained that exhibits excellent adhesion between the phosphor layer and the primer layer even after long-term environmental testing. By using this wavelength conversion sheet, a backlight and a display device can be obtained in which the phosphor layer is less prone to degradation over time. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing one embodiment of the wavelength conversion sheet of the present disclosure. [Figure 2] This is a cross-sectional view showing one embodiment of the backlight of the present disclosure. [Figure 3] This is a cross-sectional view showing another embodiment of the backlight in this disclosure. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure are described below. [Wavelength Conversion Sheet] The wavelength conversion sheet of this 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, wherein the wavelength conversion sheet film is laminated with at least a substrate layer and a primer layer, the primer is in contact with the phosphor layer, the phosphor layer and the primer layer contain element X, and 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 between the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer is C QD (atomic%) is defined as the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface, and C PR When (atomic%), C PR / C QD The value is 0.10 or less.

[0013] [Layer configuration] Figure 1 is a schematic cross-sectional view illustrating one embodiment of the wavelength conversion sheet of the present disclosure. The wavelength conversion sheet 100 in Figure 1 is an example in which a wavelength conversion sheet film 10 (10a, 10b) is provided on both surfaces of the phosphor layer 60. The wavelength conversion sheet film 10 of this disclosure comprises at least a primer layer 30 and a substrate layer 20. The primer layer 30 is in contact with the phosphor layer 60. In the example shown in Figure 1, the substrate layer 20 consists of a first substrate 20-1 and a second substrate 20-2, which are bonded together via an adhesive layer 22. The wavelength conversion sheet films 10a and 10b in Figure 1 further have a barrier layer 40 between the primer layer 30 and the substrate layer 20. In Figure 1, the barrier layer 40 has a two-layer structure consisting of a first barrier layer 42 and a second barrier layer 44. Also, the fill for the wavelength conversion sheet in Figure 1. Mu1 0a and 10b further have a diffusion layer 50 on the surface of the substrate layer 20 opposite to the surface on which the primer layer 30 is formed.

[0014] The configuration of the wavelength conversion sheet of this disclosure is not limited to Figure 1. For example, the wavelength conversion sheet of this disclosure may have a wavelength conversion sheet film with the laminated configuration shown in Figure 1 on one surface side of the phosphor layer, and a wavelength conversion sheet film with a different laminated configuration than that shown in Figure 1 on the other surface side. The laminated configuration of the wavelength conversion sheet film with a different laminated configuration is not limited as long as it satisfies the requirements of the primer layer described above. Examples of wavelength conversion sheet films with laminated configurations other than those shown in Figure 1 include the following examples. Note that each layer in the examples below has the same configuration as in Figure 1 unless otherwise specified. (1) A laminated structure having a primer layer, a substrate layer, and a diffusion layer in that order. (2) A laminated structure having a primer layer and a substrate layer in that order. (3) A laminated structure having a primer layer, a barrier layer, a single-layer substrate layer, and a diffusion layer in that order. (4) A laminated structure having a primer layer, a barrier layer, and a single-layer substrate layer in that order. (5) A laminated structure having a primer layer, a single-layer barrier layer, a substrate layer, and a diffusion layer in that order. (6) A laminated structure having a primer layer, a single-layer barrier layer, and a substrate layer in that order. (7) A laminated structure having a primer layer, a second barrier layer, a first barrier layer, a second barrier layer, a first barrier layer, a substrate layer, and a diffusion layer in this order. (8) A laminated structure having a primer layer, a second barrier layer, a first barrier layer, a second barrier layer, a first barrier layer, and a substrate layer in this order. (9) A laminated structure having a primer layer, a single-layer substrate layer, a barrier layer, and a diffusion layer in that order. (10) A laminated structure having a primer layer, a single-layer substrate layer, and a barrier layer in that order. (11) A laminated structure having a primer layer, a substrate layer, a single-layer barrier layer, and a diffusion layer in that order. (12) A laminated structure having a primer layer, a substrate layer, and a single-layer barrier layer in that order.

[0015] In the wavelength conversion sheet of this disclosure, the wavelength conversion sheet film of this disclosure is provided on one surface side of the phosphor layer, and the other surface side of the phosphor layer may be provided with a wavelength conversion sheet film that does not satisfy the requirements of the primer layer described above, i.e., a film other than the wavelength conversion sheet film of this disclosure. However, considering the degradation of the phosphor layer, it is preferable that the wavelength conversion sheet film of this disclosure is laminated on both surfaces of the phosphor layer.

[0016] [Adhesion] As will be described later, wavelength conversion sheets are manufactured by laminating a phosphor layer and a film for wavelength conversion sheets so that the phosphor layer and the primer layer are in contact. For this reason, wavelength conversion sheets are required to have good adhesion between the primer layer and the phosphor layer (referred to as "initial adhesion") before long-term environmental testing, as well as good adhesion after long-term environmental testing (referred to as "adaptive adhesion"). As described later, the phosphor layer of the wavelength conversion sheet is formed by applying a resin composition that serves as a precursor to the phosphor layer to the surface of the primer layer of the film for the wavelength conversion sheet, and then curing the resin composition. As a result of the inventors' investigations, it was found that when the precursor to 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. It is known that the adhesion between layers tends to improve as the components of the contacting layers mix together. From this, it was expected that both initial and long-term adhesion would be better if the components of the phosphor layer penetrated sufficiently deep into the interior of the primer layer. However, the inventors of this application have found that, regarding long-term adhesion, the less the penetration of phosphor layer components into the primer layer is suppressed, that is, the less the phosphor layer components that penetrate into the primer layer in the region close to the interface between the primer layer and the phosphor layer, the better the long-term adhesion.

[0017] The reason why the degree to which the components of the phosphor layer penetrate into the primer layer is related to the adhesion over time is presumed to be as follows. By applying a resin composition that serves as a precursor for the phosphor layer to the surface of the primer layer, the outermost surface of the primer layer is eroded, and components constituting the phosphor layer in the resin composition diffuse into the interior of the primer layer. Therefore, after the phosphor layer is formed by curing, it is thought that a region (hereinafter referred to as the "compatible region") is formed in the primer layer where the components of the primer layer and the components that have permeated from the phosphor layer are compatible. When a large amount of the phosphor layer components permeate into the primer layer, the concentration of phosphor layer components in the primer layer becomes high near the interface. In addition, as the phosphor layer components diffuse into the interior of the primer layer, the phosphor layer components are present at high concentrations even in areas far from the interface. Therefore, a large compatible region containing phosphor layer components at high concentrations is formed. In contrast, when a small amount of phosphor layer components permeate into the primer layer, a compatible region is formed near the interface between the primer layer and the phosphor layer, but the concentration of phosphor layer components in the compatible region is also low. From the perspective of initial adhesion, it is thought that good adhesion is achieved by the formation of compatible regions regardless of the penetration of components in the phosphor layer. On the other hand, adhesion over time is thought to be due to the relaxation of strain that occurs in the phosphor layer. As described later, the phosphor layer is usually formed thickly, between 10 μm and 200 μm. Therefore, strain occurs inside the phosphor layer due to shrinkage caused by hardening of the phosphor layer and swelling of the phosphor layer during long-term environmental testing. When there is little phosphor layer component that penetrates into the primer layer, a compatible region is formed near the interface, but there is little phosphor layer component, and most of the other areas are regions that do not contain phosphor layer components, or contain only very small amounts. It is presumed that the distribution of phosphor layer components in the primer layer as described above makes it easier for the strain in the phosphor layer to be relaxed by the primer layer, and good adhesion can be ensured even after long-term environmental testing. On the other hand, if a large amount of the phosphor layer's components penetrate the primer layer and spread at high concentrations even in the interior far from the interface, the compatible region will behave similarly to the phosphor layer. As a result, the primer layer will have difficulty mitigating the strain caused by the shrinkage and swelling of the phosphor layer. Consequently, over time, the strain generated in both the primer and phosphor layers will make delamination more likely at the interface between the primer and phosphor layers, leading to a decrease in adhesion over time.

[0018] [About element X] Element X is an element contained in a component of the resin composition that forms the precursor of the phosphor layer, but not in the resin composition that forms the precursor of the primer layer. When the phosphor layer and the primer layer come into contact, the component containing element X penetrates from the phosphor layer to the primer layer, and element X migrates into the primer layer. Therefore, when a wavelength conversion sheet is formed, both the phosphor layer and the primer layer contain element X, and the element X in the primer layer originates from the component that migrated from the phosphor layer to the primer layer. In this disclosure, we focus on element X, and the degree to which the components of the phosphor layer penetrate into the primer layer is expressed using the concentration of element X in the primer layer as an indicator.

[0019] Specifically, the element X is at least one selected from sulfur and phosphorus. These elements are components constituting the phosphor layer. Among them, the element X is preferably sulfur. Sulfur is an element derived from the thiol compound in the phosphor layer. Phosphorus is an element derived from the phosphorus-based photopolymerization initiator in the phosphor layer.

[0020] [Regarding the distribution of element X] The distribution of the element X in the thickness direction of the primer layer and the phosphor layer can be analyzed by X-ray photoelectron spectroscopy (hereinafter simply referred to as "XPS"). The average value of the ratio of the element X in the phosphor layer obtained by X-ray photoelectron spectroscopy in the region from the interface between 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 ratio of the element X in the primer layer at an arbitrary depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface is defined as C PR (atomic%). In the present disclosure, C PR / C QD needs to satisfy being 0.10 or less. [[ID=I7]]

[0021] The ratio C PR of the element X in the primer layer and the ratio C QD of the element X in the phosphor layer can be obtained by peeling at the interface between the primer layer and the phosphor layer after manufacturing the wavelength conversion sheet, and performing elemental analysis in each thickness direction on the peeled surfaces of the primer layer and the phosphor layer by XPS.

[0022] Elemental analysis by XPS can be performed, for example, according to the following procedure. First, it is determined whether peeling has occurred at the interface between the phosphor layer and the primer layer. This determination can be made by XPS analysis, but can also be made by other analysis methods. Hereinafter, the determination method using XPS analysis will be described. Survey spectra are obtained for each delamination surface of the phosphor layer and primer layer, and the elements contained in the measured surface are identified. XPS analysis of the delamination surface reveals that if an element (referred to as "element Z"), which is present in the resin composition that forms the precursor of the primer layer but not in the resin composition that forms the precursor of the phosphor layer, is detected on the delamination surface on the primer layer side but not on the delamination surface on the phosphor layer side, it can be determined that delamination occurred at the interface between the phosphor layer and the primer layer. For example, if the primer layer contains a polyurethane resin and the phosphor layer consists of a resin that does not contain nitrogen, then element Z is nitrogen. The delamination surface on the primer layer side and the delamination surface on the phosphor layer side are considered to be the interface between the primer layer and the phosphor layer, and each delamination surface is defined as having a "depth of 0 nm".

[0023] If delamination is determined to have occurred at the interface between the phosphor layer and the primer layer, the percentage of each detected element (in atomic%) is calculated using a narrow spectrum. After performing XPS analysis on the peeled surface of the primer layer, etching is performed from the peeled surface under predetermined conditions to expose a new measurement surface. XPS analysis is then performed on the surface exposed after etching to calculate the proportion of each element. By repeating this operation, depth profiles of each element can be obtained in the thickness direction of the primer layer. After performing XPS analysis on the exfoliated surface of the phosphor layer, etching is performed on the exfoliated surface under predetermined conditions to expose a new measurement surface. XPS analysis is then performed on the surface exposed after etching to calculate the proportion of each element. By repeating this operation, depth profiles of each element can be obtained in the thickness direction of the phosphor layer.

[0024] Since element X is a component of the phosphor layer, the amount of element X in the phosphor layer is sufficiently high compared to the amount of element X that migrates into the primer layer. Furthermore, even if some of element X migrates to the primer layer, the concentration of element X in the entire phosphor layer can be said to be approximately constant. For this reason, C in this disclosure QDAlthough defined as the average value of the proportion 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, it can be considered as the average value of the proportion of element X in the entire phosphor. Because the amount of etching varies depending on the etching conditions and the material being measured, it may be difficult to expose the measurement surface at a depth of 400 nm and perform XPS analysis even after adjusting the etching time. However, as mentioned above, the concentration of element X is approximately constant throughout the phosphor layer, so if a measurement point at a depth of 400 nm cannot be obtained, the average value of the proportion of element X from the interface (depth 0 nm) to the measurement point closest to 400 nm that is less than 400 nm deep is calculated.

[0025] When components in the phosphor layer easily penetrate into the primer layer, a large amount of the phosphor layer's components migrate to the primer layer, resulting in a larger amount of element X migrating to the primer layer. Consequently, the proportion of element X in the primer layer near the interface becomes higher. Furthermore, the element X that migrates to the primer layer diffuses into the interior, increasing the proportion of element X even in regions far from the interface. On the other hand, when 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 near the interface is relatively low, and element X becomes difficult to detect in regions far from the interface. Thus, the distribution of element X detected by XPS in the primer layer differs depending on the degree of penetration of the phosphor layer's components.

[0026] The proportion of element X detected in the primer layer may vary depending on the concentration of element X in the phosphor layer. Therefore, C PR / C QD This is used as an indicator of the degree to which components in the phosphor layer penetrate into the primer layer. PR / C QD A lower value indicates that the penetration of the phosphor layer components into the primer layer is suppressed.

[0027] As described later, the primer layer is preferably provided with a thickness in the range of 0.2 μm to 10 μm. The "region between 20 nm and 40 nm in the thickness direction from the interface with the phosphor layer" corresponds to the region that extends to a certain depth from the interface into the interior of the primer layer. As mentioned above, when the penetration of components from the phosphor layer is sufficiently suppressed, element X is detected to some extent near the interface of the primer layer, but the concentration of element X tends to decrease as it goes inward in the thickness direction. For this reason, when the penetration of components from the phosphor layer is sufficiently suppressed, C is detected at a certain depth from the interface (within the region between 20 nm and 40 nm in the thickness direction from the interface to the primer layer). PR / C QD The value decreases. In contrast, if a large amount of the phosphor layer components penetrate into the primer layer, even at a certain depth from the interface, C PR / C QD The value increases. C is present at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface with the phosphor layer. PR / C QD Since the value is 0.10 or less, it can be said that the diffusion of a large amount of components constituting the phosphor layer into the primer layer is suppressed. In this disclosure, at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface with the phosphor layer, PR / C QD It is preferable that the ratio is 0.08 or less, more preferably 0.06 or less, and even more preferably 0.04 or less. As explained above, it can be difficult to perform XPS analysis by exposing a measurement surface at a specific depth through etching. Therefore, in this disclosure, we define it as "any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface." The measurement surface at any depth between 20 nm and 40 nm in the thickness direction can be exposed by adjusting the etching conditions, etching time, etc. Depending on the etching conditions, multiple measurement points may be obtained in a region between 20 nm and 40 nm in thickness from the interface. In this disclosure, if multiple measurement points are obtained, C is used at all measurement points.PR / C QD The value must be 0.10 or less.

[0028] In this disclosure, the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth within the region between 1 nm and less than 20 nm in the thickness direction of the primer layer from the interface with the phosphor layer is C PR-S When defined as (atomic%), C PR-S / C QD It is preferable that the ratio is 0.04 or more and 0.20 or less, more preferably 0.04 or more and 0.15 or less, and even more preferably 0.04 or more and 0.10 or less. The region between 1 nm and less than 20 nm in the thickness direction of the primer layer from the interface with the phosphor layer is the region near the interface between the primer layer and the phosphor layer. In the region near the interface, C PR-S / C QD A value of 0.04 to 0.20 means that while penetration of the phosphor layer components is permitted, penetration is suppressed as much as possible. In the region near the interface, C PR-S / C QD By having the above range, both initial adhesion and adhesion over time can be improved. Furthermore, if multiple measurement points can be obtained in this region, C should be set at all measurement points. PR-S / C QD It is preferable that the above range is satisfied. Furthermore, the interface of the primer layer may have a different elemental distribution from the interior when measuring the depth profile by XPS due to surface oxidation, water adsorption, etc. For this reason, in this disclosure, the interface (depth 0 nm) is excluded from the "region near the interface."

[0029] In this disclosure, the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at an arbitrary depth in the region beyond 40 nm in the thickness direction of the primer layer from the interface with the phosphor layer is defined as C PR-I When defined as (atomic%), C PR-I / C QDIt is preferable that the value is 0.10 or less, more preferably 0.05 or less, and even more preferably 0.01 or less. If multiple measurement points can be obtained in the region, all measurement points te C PR-I / C QD It is preferable that the above range is satisfied. The fact that the above range is satisfied in a region more than 40 nm away from the interface with the phosphor layer in the thickness direction of the primer layer means that the penetration of components of the phosphor layer into deeper regions within the primer layer is suppressed.

[0030] In this disclosure, C at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface. PR / C QD When C is 0.10 or less, PR / C PR-S It is preferable that it is 0.60 or less. PR / C PR-S This corresponds to the ratio of element X in the region that extends a certain depth from the interface into the primer layer, relative to the ratio of element X in the region near the interface. PR / C PR-S The fact that the above range is satisfied indicates that the distribution of element X within the primer layer is not uniform. Therefore, C PR / C PR-S The fact that the above range is satisfied means that element X is not an element that constitutes a component of the resin composition that forms the precursor of the primer layer, but rather originates from a component of the resin composition that forms the precursor of the phosphor layer. 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.

[0031] In this disclosure, it is preferable that 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 0.60 or higher. This coefficient of variation is an indicator of the variation of element X in the thickness direction of the primer layer. As described above, the concentration of element X can be said to be approximately constant throughout the phosphor layer. In this case, the coefficient of variation of the proportion of element X in the thickness direction of the phosphor layer will be low. When the penetration of components in the phosphor layer into the primer layer is suppressed, element X can be detected in the primer layer near the interface, but it becomes difficult to detect in regions away from the interface. In this case, the coefficient of variation of the proportion of element X in the thickness direction of the primer layer will be high. On the other hand, when a large amount of components in the phosphor layer penetrate into the primer layer and these components diffuse into the interior of the primer layer, the difference between the proportion of element X near the interface and the proportion of element X in regions away from the interface tends to be small. In this case, the coefficient of variation of the proportion of element X in the thickness direction of the primer layer will be low. A coefficient of variation of 0.60 or higher indicates that the penetration of components in the phosphor layer into the primer layer is suppressed. The coefficient of variation is more preferably 0.75 or higher, and even more preferably 1.00 or higher. The upper limit of the coefficient of variation is preferably 5.00, and more preferably 4.00. To calculate the coefficient of variation, XPS analysis and etching are repeated to obtain the proportion of element X at at least eight locations in the thickness direction of the primer layer, thereby acquiring the depth profile of element X. Then, the mean and standard deviation are calculated using the proportion of element X at at least eight locations, and the coefficient of variation is obtained by dividing the standard deviation by the mean.

[0032] In the wavelength conversion sheet of this disclosure, the penetration of components of the phosphor layer into the primer layer is suppressed, and C is present at any depth within a region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface. PR / C QD The reason why the value is less than or equal to 0.10 is presumed to be due to the combined effect of the following factors (1) to (3).

[0033] (1) Components of the resin that make up the primer layer It is presumed that the higher the glass transition temperature of the resin contained in the resin composition that serves as the precursor for the primer layer, the more effectively the components of the phosphor layer are inhibited from penetrating into the primer layer. The primer layer in this disclosure preferably contains a polyurethane resin and a polyester resin, as described later. Means for raising the glass transition temperature of the resin that serves as the precursor of the primer layer include using a polyurethane resin with a high glass transition temperature, using a polyester resin with a high glass transition temperature, and using a combination of these. Among these, it is preferable to use a polyester resin with a high glass transition temperature, and it is even more preferable to use a combination of a polyurethane resin with a high glass transition temperature and a polyester resin with a high glass transition temperature. The high glass transition temperature of the resin constituting the primer layer indicates that the resin has a high molecular weight (weight-average molecular weight) and a high density. Therefore, it is presumed that forming the primer layer from such a resin inhibits the diffusion of components in the phosphor layer. Furthermore, it is presumed that another contributing factor is that when the primer layer is formed from such a resin, it is less susceptible to erosion by the solvent contained in the resin composition that is the precursor of the phosphor layer.

[0034] The glass transition temperature of the resin composition that serves as a precursor for 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. In other words, the glass transition temperature of the resin composition is preferably -20°C or higher and 120°C or lower, and preferably 0°C or higher and 100°C or lower. The glass transition temperature of polyurethane resins is preferably -20°C or higher, and more preferably 0°C or higher. The glass transition temperature of polyurethane resins is preferably 120°C or lower, and more preferably 100°C or lower. In other words, the glass transition temperature of polyurethane resins is preferably -20°C or higher and 120°C or lower, and preferably 0°C or higher and 100°C or lower. The glass transition temperature of polyester resin is preferably 0°C or higher, and more preferably 20°C or higher. The glass transition temperature of polyester resin is preferably 150°C or lower, and more preferably 120°C or lower. In other words, the glass transition temperature of polyester resin is preferably 0°C or higher and 150°C or lower, and preferably 20°C or higher and 120°C or lower. The glass transition temperature (T) is determined by performing indicative thermal analysis (DTA) in accordance with JIS K 7121:1987, and then using the method described in item 9.3(1) of JIS K 7121:1987 to obtain the midpoint glass transition temperature (T) from the resulting DTA curve. mg That is the case.

[0035] (2) Silane coupling agent The primer layer in this disclosure preferably contains a silane coupling agent having a reactive group. It is presumed that the inclusion of a silane coupling agent increases the crosslinking density when the resin composition that serves as the precursor of the primer layer is cured, forming a primer layer with a denser crosslinking structure, thereby suppressing the penetration of components of the phosphor layer.

[0036] (3) Solvents contained in the precursor for forming the phosphor layer As described later, the phosphor layer is usually formed by coating a resin composition (precursor) containing a phosphor and a sealing resin onto the surface of the primer layer, or by laminating a film for wavelength conversion sheets onto the coated resin composition so that the surface of the primer layer is in contact with it, and then curing the resin composition. Solvents are added to the resin composition for forming the phosphor layer for purposes such as viscosity adjustment. Depending on the type of solvent, it is possible that the solvent may penetrate the surface area of ​​the primer layer before the phosphor layer hardens, making it easier for the components of the phosphor layer to penetrate into the interior of the primer layer. It is presumed that the penetration of components of the phosphor layer can be suppressed by selecting a solvent that is less likely to erode the components of the resin composition constituting the primer layer. For example, when the primer layer contains a polyurethane resin, the surface area of ​​the primer layer tends to be easily eroded by solvents having hydrophilic groups (e.g., alcohol-based solvents such as isopropyl alcohol), so it is preferable to use a hydrophobic solvent (e.g., methyl ethyl ketone, toluene, ethyl acetate).

[0037] Each layer of the wavelength conversion sheet in this disclosure will be described in detail below. [Primer layer] The primer layer ensures good adhesion with the phosphor layer when used as a wavelength conversion sheet, preventing delamination between the wavelength conversion sheet film and the phosphor layer even in high-temperature and high-humidity environments, and thus preventing degradation of the phosphor layer. The primer layer may be a single layer or a configuration in which multiple primer layers are stacked, but a single layer configuration is particularly preferred. When multiple primer layers are stacked, the primer layer in contact with the phosphor layer is the C mentioned above. PR / C QD It satisfies the range.

[0038] In this disclosure, the primer layer preferably comprises a polyurethane resin and a polyester resin. <Polyurethane resin> By including a polyurethane resin in the primer layer, the strain caused by swelling or shrinkage of the phosphor layer when it is formed into a wavelength conversion sheet can be easily mitigated, and the initial and long-term adhesion between the phosphor layer and the primer layer can be improved. In particular, by using a polyurethane resin exhibiting a glass transition temperature within the above range, the penetration of components of the phosphor layer into the primer layer can be suppressed, and C at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface can be improved. PR / C QD This is preferable because it makes it easier for the value to be 0.10 or less.

[0039] The presence of polyurethane resin in the primer layer can be confirmed by detecting urethane bonds using methods such as X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and gas chromatography-mass spectroscopy (GCMS).

[0040] Polyurethane resins are one- or two-component polyurethane resins obtained by the reaction of a polyfunctional isocyanate with a hydroxyl group-containing compound. Polyfunctional isocyanates and hydroxyl group-containing compounds may be used individually or in combination. Examples of polyfunctional isocyanates include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and polymethylene polyphenylene polyisocyanate; and aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate. The polyfunctional isocyanate may be used as a high molecular weight modified form such as an adduct, burette, or isocyanurate, or as a block form. The modified and block forms may have functional groups such as hydroxyl groups, carboxyl groups, epoxy groups, amino groups, mercapto groups, vinyl groups, acryloyl groups, and methacryloyl groups. Among these, it is preferable to use a (meth)acrylic group-containing polyisocyanate. That is, the polyurethane resin of this disclosure includes a polyurethane resin obtained by the reaction of a polyfunctional isocyanate having a (meth)acrylic group with a hydroxyl group-containing compound. Examples of hydroxyl group-containing compounds include polyether polyols, polyester polyols, polyester polyurethane polyols, and polyacrylate polyols. Among these, polyester polyols are preferred.

[0041] The NCO / OH ratio of the polyurethane resin is preferably 1.1 or higher, more preferably 1.2 or higher, and even more preferably 1.3 or higher. An NCO / OH ratio of 1.1 or higher makes it easier to achieve good initial adhesion. However, if the NCO / OH ratio is high, the primer layer will become tacky. For this reason, the NCO / OH ratio is preferably 4.0 or lower, and more preferably 3.0 or lower.

[0042] The molecular weight (weight-average molecular weight) of the polyurethane resin is preferably 1,000 or more, more preferably 2,000 or more, preferably 100,000 or less, and more preferably 80,000 or less. In other words, the molecular weight (weight-average molecular weight) of the polyurethane resin is preferably 1,000 or more and 100,000 or less, and more preferably 2,000 or more and 80,000 or less. Because the molecular weight of the polyurethane resin is within the above range, C is present at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface. PR / C QD The value tends to fall below 0.10.

[0043] <Polyester resin> The primer layer contains polyester resin, which allows for C to be present at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface. PR / C QD This makes it easier for the glass transition temperature to be 0.10 or less, improving the initial adhesion and adhesion over time between the primer layer and the phosphor layer. In particular, it is 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 constitutes the polyol component of the polyurethane resin. The molecular weight (weight-average molecular weight) of the polyester resin is preferably 2,000 or more, more preferably 5,000 or more, preferably 700,000 or less, and more preferably 500,000 or less. In other words, the molecular weight (weight-average molecular weight) of the polyester resin is preferably 2,000 or more and 700,000 or less, and more preferably 5,000 or more and 500,000 or less. In this specification, the weight-average molecular weight is the average molecular weight measured by GPC analysis and converted to standard polystyrene.

[0044] The proportion of the polyester resin is preferably 5 parts by mass or more, and more preferably 20 parts by mass or more, per 100 parts by mass of polyurethane resin. Furthermore, the proportion of the polyester resin is preferably 60 parts by mass or less, and more preferably 40 parts by mass or less, per 100 parts by mass of polyurethane resin. In other words, 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, and even more preferably 20 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of polyurethane resin. By having the proportion of polyester resin within the above range, the penetration of components from the phosphor layer is suppressed, and C at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface PR / C QD This makes it easier for the coefficient to become 0.10 or less, improving both the initial adhesion and the adhesion over time between the primer layer and the phosphor layer.

[0045] <Phenol-based antioxidants> In this disclosure, the primer layer preferably further contains a phenolic antioxidant. The inclusion of a phenolic antioxidant in the primer layer may improve adhesion over time. Specific examples of phenolic antioxidants include dibutylhydroxytoluene (BHT), butylhydroxyanisole (BHA), 2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), and 4,4'-thiobis(6-tertiary-butyl-3-methylphenol).

[0046] <Silane coupling agent> In this disclosure, the primer layer preferably further contains a silane coupling agent. The silane coupling agent undergoes hydrolysis of a functional group at one end of its molecule, usually a chloro, alkoxy, or acetoxy group, to form a silanol group (Si-OH). This modifies the resin composition of the primer layer by covalent bonds, forming strong bonds. Therefore, it is believed that incorporating a silane coupling agent into the resin composition of the primer layer increases the crosslinking density and suppresses the penetration of components from the phosphor layer. Furthermore, in configurations where a barrier layer is provided, the adhesion between the primer layer and the barrier layer (especially the coating layer) can be improved. In this disclosure, it is preferable to use a silane coupling agent having a reactive group in order to improve the adhesion between the primer layer and the phosphor layer, and between the barrier layer and the primer layer. Examples of reactive groups include vinyl groups, (meth)acryloyl groups, amino groups, epoxy groups, and mercapto groups. In particular, it is preferable to use a silane coupling agent having a (meth)acryloyl group. By using a silane coupling agent having a (meth)acryloyl group, the crosslinking density can be further increased, the penetration of components from the phosphor layer can be suppressed, and C at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface PR / C QD It is thought that this will make it easier to control the value to 0.10 or less.

[0047] As silane coupling agents, organically functional silane monomers with binary reactivity can be used. For example, one or more aqueous solutions 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, and γ-aminopropyl silicate can be used. Among these, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane are preferred.

[0048] The silane coupling agent described above is preferably contained in an amount of 1% by mass or more, and more preferably 2% by mass or more, of the total amount of the primer layer. When the silane coupling agent content is within the above 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 can be maintained between the primer layer and the phosphor layer over time. Furthermore, in order to improve the extensibility of the primer layer and suppress the occurrence of cracks in the primer layer, the silane coupling agent is preferably contained in an amount of 30% by mass or less, and more preferably 20% by mass or less, of the total amount of the primer layer.

[0049] Furthermore, in this disclosure, after forming the primer layer, the surface of the primer layer (interface with the phosphor layer) may be subjected to surface treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, or oxidation treatment using chemicals.

[0050] In this disclosure, the primer layer may further contain a filler. The filler plays a role in adjusting the viscosity of the coating solution for forming the primer layer and improving coating suitability. Examples of fillers that can be used include powders such as calcium carbonate, barium sulfate, alumina white, silica, talc, and glass frit, as well as resin powders.

[0051] The primer layer may further contain additives such as stabilizers, crosslinkers, lubricants, UV absorbers, and others, as needed.

[0052] The thickness of the primer layer is not particularly limited, but is preferably 0.07 μm or more, more preferably 0.10 μm or more, even more preferably 0.15 μm or more, and particularly preferably 0.20 μm or more. If the primer layer is too thick, handling and productivity will decrease, so the thickness of the primer layer is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less.

[0053] The primer layer according to this embodiment preferably has a high total light transmittance, as measured according to JIS K 7361-1:1997, in order to efficiently convert light from a light source. Specifically, the primer layer according to this embodiment preferably has a total light transmittance of 85% or more, and more preferably 90% or more, as measured according to JIS K 7361-1:1997, when the primer layer is formed on a PET film (film thickness: 12 μm).

[0054] [Base material layer] The substrate layer primarily serves as a support for the primer layer. The substrate layer is preferably one with high light transmittance. Specifically, the substrate layer is preferably of 85% or higher, and more preferably of 90% or higher, in accordance with JIS K 7361-1:1997.

[0055] The material of the base layer is not particularly limited, as long as it is a resin film that does not impair the function of the wavelength conversion sheet. Examples of resins that can be used as the base layer include polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyethylene butyrate (PBT), polypropylene (PP), nylon resin, amorphous polyarylate, polysulfone, polyethersulfone, polyetherimide, fluororesin, and liquid crystal polymer. To obtain transparency, heat resistance, etc., it is preferable to use polyethylene naphthalate (PEN) or polyethylene terephthalate (PET) as the base layer. Furthermore, to obtain the oxygen permeability and water vapor permeability mentioned above, it is preferable to use polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), or nylon resin as the base layer.

[0056] The base layer may be a single-layer resin film, or it may be a multiple resin film bonded together via an adhesive layer. In the example shown in Figure 1, the base layer 20 is constructed by laminating a first base layer 20-1 and a second base layer 20-2. In this case, the first base layer 20-1 serves as a support when forming the primer layer 30. The second base layer 20-2 increases the overall thickness of the base layer 20 and provides rigidity to the wavelength conversion sheet film 10.

[0057] The overall thickness of the substrate layer is not particularly limited, but it is preferably 8 μm to 200 μm, and more preferably 8 μm to 150 μm. When the film for wavelength conversion sheets is manufactured by a winding method, the overall thickness of the substrate layer is preferably 125 μm or less. On the other hand, by increasing the overall thickness of the substrate layer, gas barrier properties against oxygen and water vapor can be obtained by the substrate layer. In this case, the barrier layer can be omitted. In order to ensure the required gas barrier properties by the substrate layer without providing a barrier layer, the overall thickness of the substrate layer is preferably 50 μm or more, and more preferably 75 μm or more.

[0058] When the substrate layer is constructed from multiple resin films, the thickness of the first substrate, which serves as the support for the primer layer, is preferably 8 μm to 50 μm, more preferably 8 μm to 25 μm, and even more preferably 8 μm to 20 μm. When the first substrate has the above thickness, handling is improved when manufacturing the primer layer by winding. Furthermore, the thickness of the second substrate is preferably 8 μm to 150 μm, and more preferably 8 μm to 100 μm. When the second substrate has the above thickness, appropriate rigidity can be given to the film for the wavelength conversion sheet. Furthermore, when manufacturing the film for the wavelength conversion sheet by winding, handling is improved. When gas barrier properties are ensured by the substrate layer as described above, the thickness of the second substrate is preferably 40 μm or more, and more preferably 50 μm or more.

[0059] The adhesive constituting the adhesive layer 22 is not particularly limited as long as it provides good adhesion between the substrate layers and satisfies the optical performance required for the wavelength conversion sheet. For example, the adhesive can be a polyvinyl acetate adhesive; a polyacrylic acid ester adhesive consisting of homopolymers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl ester, or copolymers thereof with methyl methacrylate, acrylonitrile, styrene, etc.; a cyanoacrylate adhesive; an ethylene copolymer adhesive consisting of copolymers of monomers such as vinyl acetate, ethyl acrylate, acrylic acid, methacrylic acid, etc., and ethylene; a cellulose adhesive; a polyester adhesive; a polyamide adhesive; a polyimide adhesive; an amino resin adhesive consisting of urea resin or melamine resin, etc.; a phenol resin adhesive; an epoxy adhesive; a polyurethane adhesive; a reactive (meth)acrylic adhesive; a rubber adhesive consisting of chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc.; a silicone adhesive; or an inorganic adhesive consisting of alkali metal silicate, low-melting-point glass, etc. The composition system of the adhesive constituting the adhesive layer may be any composition form such as aqueous, solution, emulsion, or dispersion, and its properties may be any form such as film, sheet, powder, or solid, and the bonding mechanism may be any form such as chemical reaction, solvent evaporation, thermal melting, or hot pressure. Alternatively, instead of the adhesives mentioned above, the adhesive layer may be formed using, for example, a thermosetting resin or a thermoplastic resin containing a crosslinking agent. Alternatively, a thermoplastic resin such as EVA, ionomer, polyvinyl butyral (PVB), or polyethylene resin may be extruded between the substrates by extrusion lamination to form the adhesive layer.

[0060] The surface of the substrate layer on the side where the primer layer is provided may be subjected to a desired surface treatment in advance to improve adhesion with the primer layer or barrier layer. Examples of surface treatments include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals.

[0061] Furthermore, as a method to improve adhesion with the primer layer or barrier layer, a base layer such as an anchor coating layer or an adhesive layer may be formed in advance. As the base layer, for example, a resin composition can be used in which polyester resin, polyamide resin, polyurethane resin, epoxy resin, phenolic resin, (meth)acrylic resin, polyvinyl acetate resin, polyolefin resin such as polyethylene or polypropylene, copolymers or modified resins thereof, cellulose resin, and others are the main components of the vehicle.

[0062] [Barrier layer] The barrier layer is a layer that imparts gas barrier properties to the film for wavelength conversion sheets. The barrier layer is a layer that can be optionally provided depending on the gas barrier properties required for the film for wavelength conversion sheets. The barrier layer may be provided on the side of the substrate layer opposite the primer layer, or between the substrate layer and the primer layer. In order to prevent damage to the barrier layer during the manufacturing process of the film for wavelength conversion sheets and the manufacturing process of the wavelength conversion sheets, and to suppress deterioration of the phosphor layer from the sheet edges when a wavelength conversion sheet is formed, it is preferable that the barrier layer be provided between the substrate layer and the primer layer.

[0063] The layers constituting the barrier layer include: "an inorganic oxide layer formed by vapor deposition of inorganic oxides," "an inorganic oxide layer formed by the sol-gel method," "a coating layer formed by applying a coating agent containing organic components such as water-soluble polymers," "a coating layer formed by applying a coating agent containing inorganic oxide components and organic components such as water-soluble polymers," and "a layer containing reaction products of a composition containing metal oxides and phosphorus compounds (hereinafter referred to as the "metal phosphorus reaction product layer")."

[0064] In the example shown in Figure 1, the barrier layer 40 is constructed by laminating a first barrier layer 42 and a second barrier layer 44. In the example shown in Figure 1, the first barrier layer 42 is located on the substrate layer 20 side. The second barrier layer 44 is in contact with the primer layer 30. The barrier layer of this disclosure is not limited to the stacked configuration shown in Figure 1. Examples of barrier layer configurations in this disclosure include a single-layer configuration of a single type selected from the group of layers constituting the barrier layer described above, a configuration in which multiple single types selected from the group are stacked, and a configuration in which two or more types selected from the group are stacked alternately (i.e., a configuration including at least a first barrier layer and a second barrier layer).

[0065] Examples of barrier layer configurations including a first barrier layer and a second barrier layer include the two-layer configuration illustrated in Figure 1, a configuration in which the first barrier layer, second barrier layer, and third barrier layer are stacked in order from the substrate layer side, and a configuration in which the first barrier layer, second barrier layer, third barrier layer, and fourth barrier layer are stacked in order from the substrate layer side. In this case, adjacent layers are made of different materials. If 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. When the barrier layer includes a first barrier layer, a second barrier layer, and a third barrier layer, it is preferable that the first barrier layer located on the substrate layer 20 side is 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. If the third barrier layer is a coating layer, its material is different from that of the coating layer of the second barrier layer. Considering barrier properties, damage to the barrier layer, etc., it is preferable that the third barrier layer is an inorganic oxide layer. When the barrier layer includes a first barrier layer, a second barrier layer, a third barrier layer, and a fourth barrier layer, it is preferable that the first barrier layer located on the substrate layer 20 side is an inorganic oxide layer. The second barrier layer is preferably a coating layer. The third and fourth barrier layers are each preferably one selected from an inorganic oxide layer and a coating layer. However, the materials of adjacent layers are different from those of the third and fourth barrier layers. Considering barrier properties, damage to the barrier layer, etc., it is preferable that the third barrier layer is an inorganic oxide layer and the fourth barrier layer is a coating layer. 。

[0066] <Inorganic oxide layer> Examples of inorganic oxide layers include layers composed of aluminum oxide, silicon oxide, magnesium oxide, or mixtures thereof. From the viewpoint of gas barrier properties, transparency, and productivity, the inorganic oxide layer is preferably a thin film layer mainly composed of aluminum oxide or silicon oxide.

[0067] Methods for forming an inorganic oxide layer include methods for forming it by depositing inorganic oxides and methods for forming it by the sol-gel method. Examples of methods for forming deposited films include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition.

[0068] The thickness of the inorganic oxide layer is not particularly limited, but is preferably between 5 nm and 500 nm. A thickness of 5 nm or more ensures uniformity of the inorganic oxide layer, providing sufficient gas barrier properties to the wavelength conversion sheet film. Considering gas barrier properties, the inorganic oxide layer is more preferably 8 nm or more, and even more preferably 10 nm or more. Furthermore, a thickness of 500 nm or less allows for sufficient flexibility in the inorganic oxide layer, reducing the occurrence of scratches and cracks in each inorganic oxide layer. Considering transparency and productivity, the inorganic oxide layer is more preferably 100 nm or less, even more preferably 50 nm or less, and particularly preferably 20 nm or less. When multiple inorganic oxide layers are provided, it is preferable that each inorganic oxide layer falls within the above thickness range.

[0069] <Coating layer> The coating layer prevents various secondary damages in subsequent processes and provides high gas barrier properties to the film for the wavelength conversion sheet. Furthermore, when an inorganic oxide layer is located between the substrate layer and the coating layer, the occurrence of scratches and cracks in the inorganic oxide layer can be reduced. Moreover, when the coating layer is provided in contact with the primer layer, the adhesion between the primer layer and the barrier layer of this disclosure can be improved.

[0070] The coating layer is a layer containing at least a water-soluble polymer. The coating layer can be formed by applying a coating agent containing organic components such as water-soluble polymers, or by applying a coating agent containing inorganic oxide components and organic components such as water-soluble polymers.

[0071] Examples of water-soluble polymers include polyvinyl alcohol, polyvinylpyrrolidone, and ethylene-vinyl alcohol copolymers. Among these, polyvinyl alcohol and ethylene-vinyl alcohol copolymers are preferred from the viewpoint of barrier properties, and polyvinyl alcohol is more preferred. In other words, the coating layer preferably contains one or more selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymers, and more preferably contains polyvinyl alcohol.

[0072] The inorganic oxide component includes at least one metal alkoxide compound. Examples of metal alkoxide compounds include metal alkoxides, metal alkoxide hydrolysates, and metal alkoxide polymers. Metal alkoxide hydrolysates and metal alkoxide polymers are obtained by hydrolyzing metal alkoxides using the sol-gel method. Metal alkoxides are M(OR) n It is a compound represented by the general formula , where 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. Specific examples of metal alkoxides include tetramethoxysilane, tetraethoxysilane, and isopropoxyaluminum. The inorganic oxide component may further contain tin chloride.

[0073] When the coating layer contains a water-soluble polymer and a metal alkoxide compound, the content of the water-soluble polymer per 100 parts by mass of the total amount of the metal alkoxide compound 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 even more preferably 8 parts by mass or more and 50 parts by mass or less.

[0074] The coating agent may contain additives such as silane coupling agents, curing agents, and dispersants, as well as solvents. A water / alcohol mixture is preferred as the solvent. As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used. In this disclosure, organoalkoxysilanes having epoxy groups are particularly preferred, and examples of such are γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. One or more of the above silane coupling agents may be used in mixture form. In this disclosure, the amount of the above silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the above alkoxysilane.

[0075] The thickness of the coating layer is not particularly limited, but is preferably between 100 nm and 500 nm. A coating layer thickness of 100 nm or more provides sufficient gas barrier properties to the film for the wavelength conversion sheet. Considering gas barrier properties, the coating layer is more preferably 120 nm or more, and even more preferably 150 nm or more. Furthermore, a coating layer thickness of 500 nm or less ensures sufficient transparency. Considering transparency and productivity, the coating layer is more preferably 300 nm or less, and even more preferably 200 nm or less. When multiple coating layers are provided, it is preferable that each coating layer is within the above thickness range.

[0076] <Metal Phosphate Reaction Layer> An example of a layer containing a reaction product of a composition comprising a metal oxide and a phosphorus compound (metal phosphorus reaction product layer) is the layer described in International Publication WO2011 / 122036. Aluminum is preferred as the metal. The thickness of the metal phosphate reactant layer is not particularly limited, but is preferably between 100 nm and 2000 nm. Layers A thickness of 100 nm or more provides sufficient gas barrier properties to the film for wavelength conversion sheets. The layers Considering gas barrier properties, the thickness is more preferably 200 nm or more, and even more preferably 300 nm or more. Furthermore, a thickness of 2,000 nm or less for the metal phosphate reactant layer can suppress cracking during film formation. Considering flexibility and other factors, the thickness of the metal phosphate reactant layer is more preferably 1,000 nm or less, and even more preferably 900 nm or less.

[0077] [Diffusion layer] The diffusion layer is a layer provided for the purpose of reducing the anisotropy of the light emission angle distribution and preventing adhesion, and is an optional layer in this disclosure. The diffusion layer includes a binder resin and a filler. By embedding the filler itself in the binder resin, and by exposing at least a portion of the filler from the binder resin to the layer surface, an uneven shape is created on the diffusion layer surface, thereby reducing the anisotropy of the light emission angle distribution. Furthermore, the uneven surface of the diffusion layer prevents the films or sheets from sticking together during the manufacturing process of the wavelength conversion sheet film or the wavelength conversion sheet itself. For example, when manufacturing the films or sheets using a winding method, handling of the films or sheets becomes easier, and surface damage can be suppressed. Also, when used as a display device, the light guide plate or Light diffusing materialIt also serves to prevent adhesion between the light guide plate and the wavelength conversion sheet, or Light diffusing material This also suppresses the occurrence of scratches caused by friction with the wavelength conversion sheet, thereby reducing the occurrence of cosmetic defects in the display device.

[0078] The binder resin for the diffusion layer is not particularly limited, as long as it satisfies the specifications required for the film and wavelength conversion sheet. For example, acrylic resins, epoxy resins, urethane resins, polyester resins, polyester acrylate resins, polyurethane acrylate resins, acrylic urethane resins, epoxy acrylate resins, etc., can be used. From the viewpoint of having high hardness, the binder resin is preferably an acrylic resin.

[0079] From the viewpoint of the optical performance required for the film for the wavelength conversion sheet and the wavelength conversion sheet, the filler is preferably a resin filler. Examples of resins used for the filler include acrylic resins and polystyrene resins. From the viewpoint of improving the scratch resistance of the diffusion layer, an acrylic resin filler is particularly preferred. Here, acrylic resin refers to a polymer containing as a monomer component an ethylenically unsaturated monomer having at least one carboxyl group or carboxylic acid ester group selected from the group consisting of methacrylic acid, acrylic acid, methacrylic acid esters, and acrylic acid esters. The refractive index difference between the filler and the resin binder is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.1 or less.

[0080] The average particle size 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. When the average particle size of the filler is 1 μm or more, at least a portion of the filler is exposed more from the surface of the diffusion layer, providing appropriate light diffusion and more effectively suppressing adhesion. When the average particle size of the filler is 50 μm or less, the filler is less likely to detach from the diffusion layer, suppressing deterioration of the diffusion layer's function and damage caused by detached filler. In this disclosure, the average particle size refers to the volume-average value d50 obtained by particle size distribution measurement using laser diffraction.

[0081] The filler content is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less, relative to the total amount of the diffusion layer. A content of 5% by mass or more provides appropriate light diffusion and effectively prevents adhesion. A content of 50% by mass or less makes it easier to meet the optical properties required for wavelength conversion sheets and wavelength conversion sheets, and also improves the film formation properties of the diffusion layer.

[0082] The diffusion layer may optionally contain additives such as stabilizers, curing agents, crosslinking agents, lubricants, UV absorbers, and others, as needed.

[0083] The thickness of the diffusion layer is not particularly limited and can be set appropriately according to the average particle size of the filler, the specifications required for the wavelength conversion sheet film and the wavelength conversion sheet itself. For example, the thickness of the diffusion layer is preferably 1.0 μm or more and 50.0 μm or less, and 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 that protrudes above the resin. The thickness of the diffusion prevention layer can be measured, for example, by observing the cross-section with a scanning electron microscope.

[0084] [Physical properties of films for wavelength conversion sheets] The wavelength conversion sheet film of this disclosure preferably has a high total light transmittance, as measured according to JIS K 7361-1:1997, in order to efficiently convert light from a light source when used as a wavelength conversion sheet. Specifically, the wavelength conversion sheet film of this disclosure preferably has a total light transmittance of 85% or more, and more preferably 90% or more, as measured according to JIS K 7361-1:1997.

[0085] The gas barrier properties of the wavelength conversion sheet film disclosed herein can be set according to requirements that take into account the degradation of the phosphor, as described later. Specifically, if the phosphor used in the wavelength conversion sheet is prone to degradation by oxygen, water vapor, etc., it is preferable that the wavelength conversion sheet film has high gas barrier properties. On the other hand, if the phosphor is not prone to degradation, high gas barrier properties are not required for the wavelength conversion sheet film. The oxygen permeability value for wavelength conversion sheet film according to JIS K 7129-2:2006 is 20 cc / m². 2 It is preferable that it is less than or equal to 10cc / m³ / day·atm. 2 It is more preferable that it be less than or equal to 5cc / m 2 It is even more preferable that it be less than or equal to day·atm, which is 2cc / m 2 It is particularly preferable that the humidity is less than or equal to 1 / day·atm. Furthermore, the water vapor transmission value for the wavelength conversion sheet film according to JIS K 7129:2008 Method B should be 20 g / m². 2 It is preferable that it is less than or equal to 10 g / m². 2 It is more preferable that it be less than 5 g / m². 2 It is even more preferable that it be less than or equal to 2 g / m². 2 It is especially preferable that it be less than or equal to one day. Oxygen permeability can be measured, for example, using the "OX-TRAN" oxygen permeability meter manufactured by MOCON Corporation (MOCON method). Similarly, water vapor permeability can be measured, for example, using the "PERMATRAN" water vapor permeability meter manufactured by MOCON Corporation. The conditions for measuring oxygen permeability are a temperature of 23°C and a relative humidity of 90%. The conditions for measuring water vapor permeability are a temperature of 40°C and a relative humidity of 90%.

[0086] [Phosphor layer] The phosphor layer is a layer used to adjust the emission wavelength of light emitted from a backlight source. The phosphor layer can be formed by laminating a encapsulating resin containing phosphors. For example, it can be formed by applying a mixture containing phosphors and encapsulating resin to the surface of a substrate layer and curing it. The phosphor layer contains one or more phosphors consisting of quantum dots.

[0087] Quantum dots that form phosphors are semiconductor particles of a predetermined size that exhibit the quantum confinement effect. When a quantum dot absorbs light from an excitation source and reaches an energetically excited state, it releases energy corresponding to its energy band gap. By adjusting the size of the quantum dot or the composition of the material, the energy band gap can be adjusted, and energy levels across various wavelength bands can be obtained. In particular, quantum dots can generate strong fluorescence in a narrow wavelength band. Therefore, display devices can be illuminated with light of the three primary colors with excellent color purity, resulting in display devices with excellent color reproduction. Preferably, the quantum dots include quantum dots that emit secondary light at a wavelength corresponding to red, quantum dots that emit secondary light at a wavelength corresponding to green, and combinations thereof. However, the quantum dots may also include quantum dots other than those that emit secondary light at a wavelength corresponding to red or green.

[0088] The core of a quantum dot is a nanometer-sized semiconductor particle, and is not particularly limited as long as it is a material that exhibits a quantum confinement effect (quantum size effect). Examples of quantum dots include semiconductor particles whose emission color is regulated by their own particle size, and semiconductor particles having a dopant. Examples of core materials include semiconductor compounds or semiconductor crystals containing semiconductors such as: Group II-VI semiconductor compounds like MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe; Group III-V semiconductor compounds like AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs, and TiSb; and Group IV semiconductors like Si, Ge, and Pb. Furthermore, semiconductor crystals containing semiconductor compounds with three or more elements, such as InGaP, can also be used. Furthermore, as a quantum dot consisting of semiconductor nanoparticles having a dopant, the above semiconductor compound is Eu 3+ , Tb 3+ Ag + Cu + It is also possible to use semiconductor crystals doped with cations of rare earth metals or transition metals. From the viewpoint of ease of fabrication, controllability of particle size to obtain visible light emission, and fluorescence quantum yield, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are preferred as core materials for quantum dots.

[0089] A quantum dot may be composed of one type of semiconductor compound or of two or more types of semiconductor compounds. For example, a quantum dot may have a structure in which a core, which acts as a light-emitting part, is covered with a protective layer (shell) (core-shell structure). When using core-shell type quantum dots, the luminescence efficiency of the quantum dots can be increased by using a semiconductor material with a higher band gap than the semiconductor compound forming the core, so that excitons are confined to the core. Examples of core-shell structures (core / shell) with such band gap size relationships include 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, and InGaP / ZnSSe.

[0090] The size of a quantum dot can be appropriately controlled by the material constituting the quantum dot so that light of the desired wavelength is obtained. As the particle size of a quantum dot decreases, the energy band gap increases. In other words, as the crystal size decreases, the emission of light from the quantum dot shifts towards the blue side, that is, towards higher energies. Generally, the particle size (diameter) of the quantum dots is preferably in the range of 0.5 nm to 20 nm, and particularly preferably in the range of 1 nm to 10 nm. The narrower the size distribution of the quantum dots, the more vivid the emission color can be obtained. The particle size of the quantum dots is the average value of the particle size measured for 20 randomly selected quantum dots by observing the cross-section of the phosphor layer using a scanning electron microscope (SEM) or transmission electron microscope (TEM). Here, the particle size is the value measured by the distance between two parallel lines that maximize the distance between the two lines when the cross-section of the quantum dot is sandwiched between them. The shape of the quantum dot is not particularly limited and may be spherical, rod-shaped, disc-shaped, or other shapes. If the quantum dot is not spherical, the particle size of the quantum dot may be the same as that of a perfectly spherical dot with the same volume. Quantum dots may be coated with resin.

[0091] The quantum dot content is adjusted as appropriate depending on the thickness of the phosphor layer, the light recycling rate in the backlight, the desired color, etc. If the thickness of the phosphor layer is within the range described later, it is preferable that the quantum dot content is 0.01 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the sealing resin of the phosphor layer.

[0092] Examples of encapsulating resins for the phosphor layer include cured products of thermosetting resin compositions and cured products of ionizing radiation-curable resin compositions. Among these, from the viewpoint of durability, cured products of thermosetting resin compositions and cured products of ionizing radiation-curable resin compositions are preferred, and cured products of ionizing radiation-curable resin compositions are more preferred.

[0093] A thermosetting resin composition is a composition containing at least a thermosetting resin, which hardens upon heating. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. These may be used individually or in combination of one or more. A curing agent may be added to these curable resins in the thermosetting resin composition as needed.

[0094] 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").

[0095] Examples of ionizing radiation-curable functional groups include ethylenically unsaturated bonding groups such as (meth)acryloyl groups, vinyl groups, and allyl groups, as well as epoxy groups and oxetanyl groups, with ethylenically unsaturated bonding groups being preferred. Among ethylenically unsaturated bonding groups, (meth)acryloyl groups are preferred. Hereinafter, ionizing radiation-curable compounds having (meth)acryloyl groups will be referred to as (meth)acrylate compounds. That is, it is preferable that the sealing resin contains a cured product of a composition containing (meth)acrylate compounds. In this specification, "(meth)acrylate" refers to methacrylate and acrylate. In this specification, "ionizing radiation" refers to electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or crosslinking molecules, and usually ultraviolet (UV) or electron beams (EB) are used, but other electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams can also be used.

[0096] The ionizing radiation-curable compound may be a monofunctional ionizing radiation-curable compound having only one of the above-mentioned functional groups, or a polyfunctional ionizing radiation-curable compound having two or more of the above-mentioned functional groups, or a mixture thereof. Among these, polyfunctional ionizing radiation-curable compounds are preferred, and polyfunctional (meth)acrylate compounds having two or more (meth)acryloyl groups are more preferred. That is, the encapsulating resin preferably contains a cured product of a polyfunctional ionizing radiation-curable compound, and more preferably contains a cured product of a polyfunctional (meth)acrylate compound.

[0097] The polyfunctional (meth)acrylate compounds may also have alkylene oxy groups. As for the alkylene oxy group, for example, an alkylene oxy group having 2 to 4 carbon atoms is preferred, an alkylene oxy group having 2 or 3 carbon atoms is more preferred, and an alkylene oxy group having 2 carbon atoms is even more preferred.

[0098] A polyfunctional (meth)acrylate compound having an alkylene oxy group may also be a polyfunctional (meth)acrylate compound having a polyalkylene oxy group containing multiple alkylene oxy groups. When a polyfunctional (meth)acrylate compound has alkylene oxy groups, the number of alkylene oxy groups in one molecule is preferably 2 to 30, more preferably 2 to 20, even more preferably 3 to 10, and even more preferably 3 to 5.

[0099] When a polyfunctional (meth)acrylate compound has an alkylene oxy group, it is preferable that it has a bisphenol structure. This tends to improve the heat resistance of the cured product. Examples of bisphenol structures include bisphenol A structure and bisphenol F structure, with bisphenol A structure being preferred. Among the polyfunctional (meth)acrylate compounds having an alkylene oxy group, ethoxylated bisphenol A type di(meth)acrylate, propoxylated bisphenol A type di(meth)acrylate, and propoxylated ethoxylated bisphenol A type di(meth)acrylate are preferred, with ethoxylated bisphenol A type di(meth)acrylate being more preferred.

[0100] Furthermore, the ionizing radiation-curable compound may be a monomer, an oligomer, a low molecular weight polymer, or a mixture thereof.

[0101] The thermosetting resin composition and the ionizing radiation-curable resin composition preferably contain a thiol compound. Thiol compounds are compounds having one or more units represented as R-SH (where R is an organic group). In this disclosure, compounds having one unit represented as R-SH are referred to as monofunctional thiol compounds, and compounds having two or more units represented as R-SH are referred to as polyfunctional thiol compounds.

[0102] The thiol compound may be a monofunctional thiol compound, but a polyfunctional thiol compound is preferred to improve the intensity of the phosphor layer. Among polyfunctional thiol compounds, a trifunctional thiol compound or a tetrafunctional thiol compound is more preferred.

[0103] Thiol compounds undergo a reaction (thiol-ene reaction) with compounds having radically polymerizable functional groups in the presence of a radical polymerization initiator, as shown in the following formula. The thiol-ene reaction is preferable because it can suppress polymerization shrinkage, thereby easing the stress generated during the curing of the phosphor layer, and consequently improving the interlayer adhesion of the wavelength conversion sheet. Furthermore, the cured product obtained by the thiol-ene reaction is preferable because it tends to have good heat resistance. In addition, since the refractive index of thiol compounds (approximately 1.53) is higher than that of polyfunctional (meth)acrylate compounds (approximately 1.45), the degree of freedom in adjusting the refractive index of the phosphor layer can be increased. The following reaction is an example of a reaction between a monofunctional thiol compound and a compound having one radical polymerizable functional group. Reaction products of polyfunctional thiol compounds and compounds having two or more radical polymerizable functional groups are thought to readily form dendrimer structures. When a dendrimer structure is formed, the flexibility of the phosphor layer is increased, and the phosphor layer itself is thought to exhibit excellent stress relaxation properties. Examples of radical polymerizable functional groups include ethylenically unsaturated bond-containing groups such as (meth)acryloyl groups, vinyl groups, and allyl groups.

[0104] [ka] [In the formula, R 1 and R 2 [ is an organic group.]

[0105] Specific examples of monofunctional thiol compounds include hexanethiol, 1-heptanethiol, 1-octanethiol, 1-nonanethiol, 1-decanethiol, 3-mercaptopropionic acid, methyl mercaptopropionate, methoxybutyl mercaptopropionate, octyl mercaptopropionate, tridecyl mercaptopropionate, 2-ethylhexyl-3-mercaptopropionate, and n-octyl-3-mercaptopropionate.

[0106] Specific examples of polyfunctional thiol compounds include ethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptopropionate), tetraethylene glycol bis(3-mercaptopropionate), 1,2-propylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptobutyrate), 1,4-butanediol bis(3-mercaptopropionate), and 1,4-butanediol bis(3-mercaptopropionate). Captobutyrate), 1,8-octanediol bis(3-mercaptopropionate), 1,8-octanediol bis(3-mercaptobutyrate), hexanediol bisthioglycolate, trimethylolpropantrys(3-mercaptopropionate), trimethylolpropantrys(3-mercaptobutyrate), trimethylolpropantrys(3-mercaptoisobutyrate), trimethylolpropantrys(2-mercaptoisobutyrate), trimethylolpropantrys(2-mercaptoisobutyrate), trimethyl Rollpropane tristhioglycolate, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolethanetris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptoisobutyrate), pentaerythritol tetrakis(2-mercaptoisobutyrate), dipenta Examples include erythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(2-mercaptopropionate), dipentaerythritol hexakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptoisobutyrate), dipentaerythritol hexakis(2-mercaptoisobutyrate), pentaerythritol tetrakisthioglycolate, and dipentaerythritol hexakisthioglycolate.

[0107] In an ionizing radiation-curable resin composition (or thermosetting resin composition), the mass ratio of the ionizing radiation-curable compound (or thermosetting resin) to the thiol compound (resin composition / thiol compound) is preferably 80 / 20 to 35 / 65, and more preferably 70 / 30 to 40 / 60.

[0108] When the ionizing radiation-curable compound is an ultraviolet-curable compound, the ionizing radiation-curable composition preferably contains additives such as photopolymerization initiators and photopolymerization accelerators. Phosphorus-based photopolymerization initiators can be used as photopolymerization initiators. Examples of phosphorus-based photopolymerization initiators include Omnirad819 (manufactured by IGM Resins BV) and Omnirad TPO H (manufactured by IGM Resins BV).

[0109] The phosphor layer may contain internally diffusing particles. The internally diffusing particles can be either organic or inorganic. Examples of organic particles include those made of polymethyl methacrylate, acrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone resin, fluororesin, and polyester. Examples of inorganic fine particles include those made of silica, alumina, zirconia, and titania. The shape of the internally diffusing particles can be spherical, disc-shaped, rugby ball-shaped, or irregular. Furthermore, the internally diffusing particles may be hollow particles, porous particles, or solid particles.

[0110] The content of internally diffusing particles is preferably 1 to 40 parts by mass, and more preferably 3 to 30 parts by mass, per 100 parts by mass of the sealing resin.

[0111] The average particle size of the internal diffusion particles is preferably 1 μm to 7 μm, and more preferably 1 μm to 3 μm. The average particle size of the internal diffusion particles is determined by observing the cross-section of the phosphor layer using a scanning electron microscope (SEM) or transmission electron microscope (TEM) and randomly selecting 20 internal diffusion particles. particle This is the average particle size measured for the quantum dot. The particle size is the distance between two parallel lines that maximize the distance between the lines when the cross-section of the quantum dot is sandwiched between them.

[0112] The thickness of the phosphor layer is preferably 10 μm to 200 μm, more preferably 20 μm to 150 μm, and even more preferably 30 μm to 130 μm.

[0113] Refractive index n of the phosphor layer Z It is preferably 1.40 or more and 1.55 or less, more preferably 1.43 or more and 1.52 or less, and even more preferably 1.46 or more and 1.50 or less. Refractive index n of the phosphor layer Z This is largely governed by the refractive index of the encapsulating resin. The phosphor layer has a low quantum dot content, and even if it contains an internal diffusing agent, the particle size of the internal diffusing agent is larger than the wavelength of light and therefore does not affect the refractive index of the layer.

[0114] [Manufacturing method for wavelength conversion sheets] The method for manufacturing a wavelength conversion sheet according to the present disclosure includes (1) the step of manufacturing a film for a wavelength conversion sheet, and (2) the step of bringing the film for a wavelength conversion sheet into contact with a phosphor layer.

[0115] The wavelength conversion sheet film of this disclosure is manufactured, for example, by the following process. (1-1) Barrier layer formation process A barrier layer is formed on one surface of the substrate layer (or the first substrate). Note that the barrier layer formation step can be omitted.

[0116] As illustrated in Figure 1, when the coating layer and inorganic oxide layer are used as barrier layers, first an inorganic oxide layer is formed on the substrate layer (or the first substrate), and then the coating layer is formed on the inorganic oxide layer. Furthermore, the surface on which the barrier layer of the base material layer (or the first base material) is formed may have the above-described surface treatment applied in advance, or a base layer may have been formed thereon.

[0117] Inorganic oxide layers can be formed by vapor deposition or sol-gel methods. Methods for vapor deposition of inorganic oxides include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition.

[0118] 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 solvents, etc., to obtain the desired gas barrier properties, thickness, viscosity, etc. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods.

[0119] The metal phosphate reactant layer can be formed by the method described in International Publication WO2011 / 122036.

[0120] (1-2) Primer layer formation process A primer layer is formed on the substrate layer or barrier layer. The primer layer can be formed by applying a coating agent of a resin composition containing the polyurethane resin and curing it by heating. The coating agent is prepared by adding a solvent to the coating agent to obtain the desired thickness, viscosity, etc. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods. The heating temperature is preferably in the range of 50°C to 180°C.

[0121] As shown in Figure 1, when the substrate layer is constructed by laminating multiple substrates, the method for manufacturing a wavelength conversion sheet film according to this disclosure further includes (1-2) a primer layer formation step followed by (1-3) an adhesion step. (1-3) Adhesion process In the bonding process, the side of the first substrate opposite the barrier layer and the second substrate are laminated together with an adhesive layer in between. Specifically, the adhesive described above is applied to the surface of the first substrate, the second substrate is placed on top, and the adhesive layer is cured. Alternatively, a coating agent containing a crosslinking agent and resin is applied to the surface of the first substrate, the second substrate is placed on top, and the coating agent is crosslinked by heat or other means. The adhesive or coating agent can be applied by roll coating, gravure coating, knife coating, dip coating, spray coating, other coating methods, or printing methods. Alternatively, molten thermoplastic resin may be poured between the first and second substrates by extrusion lamination, and then cooled to form an adhesive layer.

[0122] Furthermore, if a diffusion layer is provided as shown in Figure 1, it is preferable that the diffusion layer is already formed on the base layer or the second base layer. Specifically, a coating agent containing resin, filler, solvent, etc., can be applied to the surface opposite to the surface where the barrier layer of the base material or second base material is provided, and then cured to form the coating. Methods for applying the coating agent include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods.

[0123] (2) Step of bringing the phosphor layer and the film for the wavelength conversion sheet into contact. In this process, the primer layer and the phosphor layer of the wavelength conversion sheet film are brought into contact. Below, we will give an example of a method for manufacturing a wavelength conversion sheet in which the phosphor layer is sandwiched between wavelength conversion sheet films. Specifically, a mixture containing a phosphor and a sealing resin (a resin composition that is a precursor to the phosphor layer) is prepared. In this disclosure, a solvent that does not easily corrode the components of the resin composition constituting the primer layer is used as the solvent for the mixture. For example, if the primer layer contains a cured product of a polyurethane resin composition, a hydrophobic solvent such as ethyl acetate, toluene, or methyl ethyl ketone is used. (1) The above mixture is applied to the surface of the primer layer of the wavelength conversion sheet film prepared in (1) to form a coated film. Methods for applying the mixture include roll coating, gravure coating, knife coating, dip coating, spray coating, and other coating methods. Then, the surface opposite the phosphor layer is brought into contact with the primer layer of another wavelength conversion sheet film prepared in (1). After that, the coated film is cured by heat, ionizing radiation, etc., to obtain a wavelength conversion sheet.

[0124] [Backlight] The backlight of the present disclosure comprises at least one light source that emits primary light, an optical plate disposed adjacent to the light source for light guidance or diffusion, and a wavelength conversion sheet (quantum dot sheet) disposed on the light-emitting side of the optical plate, wherein the wavelength conversion sheet is the wavelength conversion sheet of the present disclosure described above.

[0125] The backlight 200 of this disclosure can be either an edge-lit backlight as shown in Figure 2, or a direct-lit backlight as shown in Figure 3.

[0126] The optical plate 120 used in the edge-lit backlight 201 shown in Figure 2 is an optical component for guiding the primary light emitted from the light source 110, and is a so-called light guide plate 121. The light guide plate 121 has a substantially flat shape, for example, formed so that at least one surface is the light incident surface and the other surface substantially perpendicular to it is the light emission surface.

[0127] The light guide plate is mainly composed of a matrix resin selected from highly transparent resins such as polymethyl methacrylate. The light guide plate may also contain resin particles with different refractive indices from the matrix resin, as needed. Each surface of the light guide plate may not be a uniform plane but may have a complex surface shape, and may be provided with a dot pattern or the like.

[0128] The optical plate 120 used in the direct-lit backlight 202 shown in Figure 3 is an optical component (light diffusing material 122) that has light-diffusing properties to make the pattern of the light source 110 difficult to see. Examples of the light diffusing material 122 include a milky white resin plate with a thickness of about 1 to 3 mm.

[0129] Edge-lit and direct-lit backlights may, in addition to the light source, optical plate, and wavelength conversion sheet described above, include one or more components selected from reflectors, light-diffusing films, prism sheets, brightness-enhancing films (BEF), and reflective polarizing films (DBEF), depending on the purpose. The reflector is positioned on the side opposite to the light-emitting surface of the optical plate. The light-diffusing film, prism sheet, brightness-enhancing film, and reflective polarizing film are positioned on the light-emitting surface side of the optical plate. By including one or more components selected from reflectors, light-diffusing films, prism sheets, brightness-enhancing films, and reflective polarizing films, a backlight with an excellent balance of front brightness, viewing angle, etc., can be made.

[0130] In edge-lit and direct-lit backlights, the light source 110 is a light emitter that emits primary light, and it is preferable to use a light emitter that emits primary light with a wavelength corresponding to blue. The primary light with a wavelength corresponding to blue preferably has a peak wavelength in the range of 380 nm to 480 nm. More preferably, the peak wavelength is 450 nm ± 7 nm, more preferably 450 nm ± 5 nm, more preferably 450 nm ± 3 nm, and more preferably 450 nm ± 1 nm. From the viewpoint of simplifying and miniaturizing the device for installing the backlight, the light source 110 is preferably an LED light source, and more preferably a monochromatic blue LED light source. Alternatively, a red phosphor may be coated on a monochromatic blue LED light source to create a light source that emits both blue and red light. There is at least one light source 110, and from the viewpoint of emitting sufficient primary light, there are preferably multiple light sources.

[0131] [Display device] Examples of display devices include liquid crystal displays. A liquid crystal display device comprises a backlight and a liquid crystal panel. The backlight is the backlight of the present disclosure described above.

[0132] The liquid crystal panel is not particularly limited, and a general-purpose liquid crystal panel for a liquid crystal display device can be used. For example, a liquid crystal panel having a common structure in which a liquid crystal layer is sandwiched between glass plates, specifically those with display methods such as TN, STN, VA, IPS, and OCB, can be used.

[0133] The liquid crystal display device further includes a polarizing plate and a color filter, etc. General-purpose polarizing plates and color filters can be used.

[0134] The wavelength conversion sheet of this disclosure exhibits particularly excellent adhesion between the film for the wavelength conversion sheet and the phosphor layer. Therefore, when the wavelength conversion sheet of this disclosure is applied to a display device (liquid crystal display device), degradation of the phosphor layer due to the intrusion of water vapor and oxygen from the external environment can be effectively suppressed. As a result, a display device with a backlight source exhibiting excellent environmental stability can be created.

[0135] The uses of the display device described herein are not particularly limited, but it is especially preferred for use in small electronic devices such as televisions, smartphones, and tablets. [Examples]

[0136] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited in any way by these examples.

[0137] 1. Evaluation and Measurement The following measurements and evaluations were performed on wavelength conversion sheets manufactured using the method described below. The results are shown in Table 1. Unless otherwise specified, and unless the tests were conducted under specific environmental conditions, the atmosphere during each measurement and evaluation was 23±5°C and 40-65% relative humidity. Before starting each measurement and evaluation, the target sample was exposed to the aforementioned atmosphere for at least 30 minutes.

[0138] 1-1.XPS analysis Test specimens measuring 25 mm x 150 mm were cut from the wavelength conversion sheets of the examples and comparative examples. The test specimens were taken excluding the area 1 cm inward from the edge of the wavelength conversion sheet. The short edges of the test specimens were grasped on both sides and peeled off at an angle of approximately 90 degrees. For the two test pieces after peeling, XPS analysis samples were collected respectively. For these samples, the X-ray photoelectron spectra of the peeled surfaces were measured using an X-ray photoelectron spectrometer (ESCA3400 manufactured by Shimadzu Corporation). The measurement conditions will be described later. The elements on the peeled surfaces of each test piece were identified by the survey spectra. When nitrogen was detected on the peeled surface of one test piece and not detected on the peeled surface of the other test piece, it was determined that appropriate peeling occurred at the interface between the primer layer and the phosphor layer, and subsequent analysis was performed. The test piece on which nitrogen was not detected was identified as having the structure of a film for a wavelength conversion sheet on which a phosphor layer was laminated, and the peeled surface was the surface of the phosphor layer. The test piece on which nitrogen was detected was identified as having the structure of only the film for the wavelength conversion sheet, and the peeled surface was the surface of the primer layer.

[0139] For the test piece on the primer layer side and the test piece on the phosphor layer side, the ratios of the elements detected using the narrow spectra were calculated. Thereafter, etching of the measured surface was performed under the conditions described later to expose a new measured surface. For the exposed measured surface, the X-ray photoelectron spectrum was measured under the same conditions, and the ratios of each element were calculated. Specifically, for each narrow spectrum of C1s, N1s, O1s, Al2p, Si2p, and S2p, using the analysis software (Vision Processing) attached to the apparatus, the background was subtracted by the Shirley method, and the integrated intensity (area) of the peak of each element was obtained. Using the obtained integrated intensity (area), the ratio (atomic%) of each element was calculated. For the sheet on the primer layer side and the sheet on the phosphor layer side, etching, measurement, and calculation of the ratio of elements were repeated respectively to obtain the depth profiles of the elements contained in the primer layer and the phosphor layer.

[0140] <X-ray photoelectron spectrum measurement conditions> Apparatus: ESCA3400 manufactured by Shimadzu Corporation X-ray source: MgKα (hν = 1253.6 eV) Emission current: 20 mA Acceleration voltage: 10 kV Photoelectron capture angle: 90° Measurement area: 6mmφ Neutralization of static charge: Not performed Resolution: Low Scan control: BE Peak shift correction: Corrects the peak of CC to 285.0 eV at the C1s peak. <Etching conditions> Equipment: Attached to the X-ray photoelectron spectroscopy analyzer Ionic species: Ar + (Argon monoatomic ion) Ar gas introduction pressure: 2.0 × 10 -2 Pa Emission current: 30mA (measured on the primer layer side in Example 1), 20mA (other measurements) Acceleration voltage: 0.3kV (measured on the primer layer side in Example 1), 0.2kV (other measurements)

[0141] 1-2. Initial adhesion evaluation Test specimens measuring 25 mm x 150 mm were cut from the wavelength conversion sheets of the examples and comparative examples. The test specimens were taken from three arbitrary locations, excluding the area 1 cm inward from the edge of the wavelength conversion sheet. A peeling test was performed using a benchtop material testing machine (STA-1150, manufactured by Takachiho Seiki Co., Ltd.) at a temperature of 23°C, with a tensile speed of 300 mm / min, a peeling direction of 180°, and a chuck distance of 15 mm. The peel strength between the primer layer and the phosphor layer was measured for each test specimen. The average value of the obtained peel strengths was taken as the initial peel strength (before the high temperature and high humidity test).

[0142] 1-3. Evaluation of adhesion over time The wavelength conversion sheets of the examples and comparative examples were placed in a constant temperature and humidity chamber adjusted to 60°C and 90%RH. After 500 hours, the wavelength conversion sheets were removed from the constant temperature and humidity chamber. The peel strength of each specimen of the extracted wavelength conversion sheet was measured according to the procedure described in 1-2 above. The specimens were taken from three arbitrary locations, excluding the area 1 cm inward from the edge of the wavelength conversion sheet. The average peel strength of the obtained specimens was used as the peel strength at each elapsed time.

[0143] 2. Preparation of Sample <Example 1> As the first substrate, an aluminum oxide thin film (AlOx, target thickness: 8 nm) was deposited on a PET film (thickness: 12 μm) by vacuum evaporation to form an inorganic oxide layer.

[0144] Tetraethoxysilane was mixed with a solution (pH 2.2) of water, isopropyl alcohol, and 0.5 N hydrochloric acid while cooling to 10°C to prepare Solution A. Separately, Solution B was prepared by mixing polyvinyl alcohol with a saponification value of 99% or more and isopropyl alcohol. Solution A and Solution B were mixed to prepare a coating solution for forming a coating layer (solid content: 5%). Next, the coating solution for forming a coating layer was applied onto the inorganic oxide layer by gravure printing and heat-treated at 180°C for 60 seconds to form a coating layer with a thickness of 180 nm.

[0145] Next, Coating Liquid 1 for forming a primer layer with the following formulation was prepared. The NCO / OH ratio of Coating Liquid 1 for forming a primer layer was 3.0. <Coating Liquid 1 for forming a primer layer> · Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solid content: 30%) 50 parts by mass · Isocyanate (mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 1 mass%) 5 parts by mass · Polyester (Tg: 70°C) 20 parts by mass · Silane coupling agent (3-methacryloxypropyltrimethoxysilane) 1 part by mass · Silica powder (average particle size 3 μm) 0.5 parts by mass · Dibutylhydroxytoluene (BHT) 1 part by mass · Solvent (methyl ethyl ketone) 五十 parts by mass

[0146] Next, Coating Liquid 1 for forming a primer layer was applied onto the coating layer. The coating amount of the coating liquid was 0.5 g / m 2The mixture was then dried at 80°C for 60 seconds to form a primer layer with a thickness of 0.4 μm (400 nm).

[0147] A urethane-based adhesive (manufactured by Rock Paint Co., Ltd., product names "RU-004, H-1") was applied by gravure printing to the surface of the first substrate opposite to the surface where the inorganic oxide layer and primer layer were formed, and then dried to form an adhesive layer with a thickness of 4 μm.

[0148] Next, a PET film (thickness: 100 μm) was placed on the adhesive layer side of the first substrate as the second substrate, and the first and second substrates were bonded together under conditions of nip pressure: 0.2 MPa and line speed: 50 m / min to produce a film for wavelength conversion sheets.

[0149] In a glove box purged with nitrogen to an oxygen concentration of 300 ppm or less, quantum dots (phosphors) and amino-modified silicone were mixed in the composition ratio shown below, and stirred with a magnetic stirrer for 4 hours while being heated in a water bath at 90°C. After that, the mixture was filtered through a polypropylene filter with a pore size of 0.2 μm to obtain a CdSe / ZnS core-shell type quantum dot dispersion. • Quantum dot 1 (emission peak: 540nm, serial number: 748056, manufactured by Sigma-Aldrich) 0.9 parts by mass • Quantum dot 2 (emission peak: 630nm, serial number: 790206, manufactured by Sigma-Aldrich) 0.9 parts by mass • Amino-modified silicone (manufactured by Genesee, part number: GP-344, viscosity: 670 mPa·s) 99 parts by mass

[0150] Using the quantum dot dispersion prepared above, a resin composition for phosphor layer formation was prepared according to the following formulation. • Polyfunctional acrylate compound (ethoxylated bisphenol A diacrylate; trade name "ABE-300" of Shin-Nakamura Chemical Industry Co., Ltd.) 58.11 parts by mass • Polyfunctional thiol compound (pentaerythritol tetrakis(3-mercaptopropionate); trade name "PEMP" from SC Organic Chemicals Co., Ltd.) 38.74 parts by mass • Photopolymerization initiator (IGM Resins BV's product name "Omnirad TPO H") 0.5 parts by mass • Quantum dot dispersion 1.61 parts by mass • Ethyl acetate 0.79 parts by mass Titanium dioxide (Chemours brand name "Typure R-706"; particle size 0.36 μm) 0.25 parts by mass

[0151] The above resin composition was applied to the primer layer of the wavelength conversion sheet film to a thickness of 100 μm (after drying) to form a phosphor layer. Another wavelength conversion sheet film prepared using the above procedure was laminated onto the phosphor layer such that the primer layer was in contact with the phosphor layer. Subsequently, the wavelength conversion sheet of Example 1 was prepared by UV curing the sealing resin of the phosphor layer.

[0152] <Example 2> A primer layer forming solution 2 was prepared according to the following formulation, and the wavelength conversion sheet of Example 2 was fabricated in the same procedure as in Example 1, except that a primer layer with a thickness of 0.4 μm (400 nm) was applied. The difference between primer layer forming solution 2 and primer layer forming solution 1 is that a polyester with a higher glass transition temperature was used. The NCO / OH ratio of primer layer forming solution 2 was 3.0. <Coating solution for primer layer formation 2> • Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solids content: 30%) 50 parts by mass • Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester (Tg: 80℃) 20 parts by mass • Silane coupling agent (3-methacryloxypropyltrimethoxysilane) 1 part by mass • Silica powder (average particle size 3 μm) 0.5 parts by mass • Dibutylhydroxytoluene (BHT) 1 part by mass • Solvent (methyl ethyl ketone) 50 parts by mass

[0153] <Example 3> A primer layer forming solution 3 was prepared according to the following formulation, and the wavelength conversion sheet of Example 3 was fabricated in the same procedure as in Example 1, except that a primer layer with a thickness of 0.4 μm (400 nm) was applied. The difference between primer layer forming solution 3 and primer layer forming solution 1 is the amount of polyester blended. The NCO / OH ratio of primer layer forming solution 3 was 3.0. <Coating solution for primer layer formation 3> • Polyester polyurethane polyol (hydroxyl value: 5.0 mg KOH / g, solids content: 30%) 50 parts by mass • Isocyanate (a mixture of 1,3-xylylene diisocyanate and polymethyl methacrylate, NCO content: 10% by mass) 5 parts by mass Polyester (Tg: 70℃) 30 parts by mass • Silane coupling agent (3-methacryloxypropyltrimethoxysilane) 1 part by mass • Silica powder (average particle size 3 μm) 0.5 parts by mass • Dibutylhydroxytoluene (BHT) 1 part by mass • Solvent (methyl ethyl ketone) 50 parts by mass

[0154] <Comparative Example 1> The wavelength conversion sheet for Comparative Example 1 was prepared under the same conditions as for Example 1, except that the primer layer formulation was changed as described below, and a film for wavelength conversion sheets with a 0.3 μm (300 nm) thick primer layer was used. • Polyester polyurethane polyol (hydroxyl value: 62 mg KOH / g, solids content 20% by mass) 50 parts by mass • Silane coupling agent (3-glycidoxypropylmethyldimethoxysilane) 1 part by mass • Silica filler (average particle size 5 μm) 1 part by mass • Hardener (1,6-hexamethylene diisocyanate, 35% solids content) 1 part by mass • Solvent (methyl ethyl ketone) 50 parts by mass

[0155] 3.Results Table 1 shows the proportion of each element in the depth direction of the primer layer for the wavelength conversion sheet of Example 1, and Table 2 shows the proportion of each element in the depth direction of the phosphor layer for the wavelength conversion sheet of Example 2, and Table 3 shows the proportion of each element in the depth direction of the primer layer for the wavelength conversion sheet of Example 2, and Table 4 shows the proportion of each element in the depth direction of the phosphor layer for the wavelength conversion sheet of Example 3, and Table 5 shows the proportion of each element in the depth direction of the primer layer for the wavelength conversion sheet of Example 3, and Table 6 shows the proportion of each element in the depth direction of the phosphor layer for the wavelength conversion sheet of Comparative Example 1, and Table 7 shows the proportion of each element in the depth direction of the primer layer for the wavelength conversion sheet of Comparative Example 1, and Table 8 shows the proportion of each element in the depth direction of the phosphor layer for the wavelength conversion sheet of Comparative Example 1. In Tables 1-8, elements other than carbon (C), nitrogen (N), oxygen (O), and sulfur (S) are grouped together as "Others." In this example, element X is sulfur. In each table, the percentage of each element is shown to one decimal place. The unit of the percentage of each element is atomic%.

[0156] Tables 1-8 show the etching time converted to the etching depth. The depth conversion was performed using the following procedure. First, a wavelength conversion sheet was prepared as a sample, and ultrathin sections were taken from the cross-section of the wavelength conversion sheet using an ultramicrotome and a diamond knife. These ultrathin sections were observed using a scanning electron microscope (SEM, Hitachi High-Tech SU8000) in transmission mode, and the film thicknesses of the primer layer and phosphor layer were measured. Measurements were taken at three arbitrary locations. For the primer layer and phosphor layer, the average of the film thicknesses at the three locations was taken as the film thickness of the primer layer and the film thickness of the phosphor layer, respectively. Next, the primer layer was exposed from the wavelength conversion sheet of the same sample using the method described above, and XPS analysis was performed using the procedure described in 1-1 to obtain the depth profiles of each element contained in the primer layer. Here, etching and measurement were repeated until a measurement point was obtained in which the proportion of each element changed significantly, and the proportion of the element (Si) contained in the barrier layer located below the primer layer exceeded 5 atomic%. Then, the etching time that represents the inflection point in the proportions of carbon (C), oxygen (O), and silicon (Si) was obtained. This etching time was considered the interface between the primer layer and the barrier layer (coating layer). The etching rate was calculated from the etching time at the inflection point and the thickness of the primer layer, and each etching time was converted to depth using the etching rate. For the phosphor layer, the depth profile of each element was obtained using the same procedure as above. For the primer layer, etching and measurement were repeated until nitrogen (N) was detected. The etching time at the inflection point for the proportion of nitrogen (N) was obtained. This etching time was considered the interface between the phosphor layer and the primer layer of another wavelength conversion sheet film. The etching rate was calculated from the etching time at the inflection point and the thickness of the phosphor layer, and each etching time was converted to depth using the etching rate. In each table, the peeling surface on the primer layer side and the peeling surface on the phosphor layer side were both set to a depth of 0 nm. For the phosphor layer side (Tables 2, 4, 6, 8), results up to an etching time of 3500 seconds are shown.

[0157] [Table 1]

[0158] [Table 2]

[0159] [Table 3]

[0160] [Table 4]

[0161] [Table 5]

[0162] [Table 6]

[0163] [Table 7]

[0164] [Table 8]

[0165] First, referring to Tables 2, 4, 6, and 8, the proportion of sulfur is almost constant in the range from a depth of 0 nm to 392 nm. Although the phosphor layer is 100 μm thick, the proportion of sulfur does not change significantly in the range from a depth of 0 nm to 392 nm, so it can be said that the proportion of sulfur is approximately constant throughout the entire phosphor layer. Therefore, in this example, for each of Tables 2 (Example 1), 4 (Example 2), 6 (Example 3), and 8 (Comparative Example 1), the average value of the sulfur proportion from a depth of 0 nm to 392 nm (etching time from 0 seconds to 3500 seconds) was calculated, and this average value was used to determine the proportion of sulfur in the phosphor layer (C QD ) was considered to be.

[0166] In Tables 1, 3, 5, and 7, the average value C of the ratio of sulfur in the phosphor layer QD to the ratio of sulfur in the primer layer at each etching time is represented as C PR / C QD as shown. In Tables 1 and 3, C PR / C QD is shown to two decimal places. Note that in both the examples and the comparative examples, phosphorus (P) was not detected.

[0167] In Table 1, the ratios of carbon (C), oxygen (O), and others (including silicon (Si)) changed significantly between the measurement points at an etching time of 1500 seconds and 2000 seconds. From this result, the etching time at the midpoint of 1750 seconds was regarded as the bending point. The etching was calculated by dividing the film thickness (400 nm) of the primer layer by the etching time at the bending point. Using this etching rate, the etching time was converted to depth. Therefore, in Table 1 (Example 1), the data from a depth of 0 nm to 343 nm is for the primer layer. speed In Table 3 (Example 2), there was a significant change between the measurement points at an etching time of 1500 seconds and 2000 seconds. From this result, the etching time at the midpoint of 1750 seconds was regarded as the bending point, and the etching time was converted to depth in the same manner as in Example 1. In Example 2, the data from a depth of 0 nm to 343 nm is for the primer layer. In Table 5 (Example 3), there was a significant change between the measurement points at an etching time of 1500 seconds and 2000 seconds. From this result, the etching time at the midpoint of 1750 seconds was regarded as the bending point, and the etching time was converted to depth in the same manner as in Example 1. In Example 3, the data from a depth of 0 nm to 343 nm is for the primer layer.

[0168] ​In Table 7, the proportions of carbon (C), oxygen (O), and other elements (including silicon (Si)) changed significantly between the measurement point at 2500 seconds and the measurement point at 3000 seconds of etching time. Based on this result, the etching time of 2750 seconds, which is the midpoint, was considered the inflection point. The etching rate was calculated by dividing the primer layer thickness (300 nm) by the etching time at the inflection point. This etching rate was used to convert the etching time into depth. Therefore, in Table 7 (Comparative Example 1), the data for the primer layer ranges from a depth of 0 nm to 273 nm.

[0169] For Tables 1, 3, and 5, the mean and standard deviation of the sulfur content were calculated using data for etching times of 0 to 1500 seconds, corresponding to the primer layer. For Table 7, the mean and standard deviation of the sulfur content were calculated using data for etching times of 0 to 2500 seconds, corresponding to the primer layer. From the obtained mean and standard deviation, the coefficient of variation of the sulfur content in the primer layer was determined. Furthermore, for Tables 2, 4, 6, and 8, the mean and standard deviation of the sulfur content were calculated using data for etching times of 0 to 3500 seconds. From the obtained mean and standard deviation, the coefficient of variation of the sulfur content in the phosphor layer was determined. Table 9 shows the mean, standard deviation, and coefficient of variation of the sulfur content for Example 1. Table 10 shows the mean, standard deviation, and coefficient of variation of the sulfur content for Example 2. Table 11 shows the mean, standard deviation, and coefficient of variation of the sulfur content for Example 3. Table 12 shows the mean, standard deviation, and coefficient of variation of the sulfur content for Comparative Example 1. The mean, standard deviation, and coefficient of variation are each shown to two decimal places.

[0170] [Table 9]

[0171] [Table 10]

[0172] [Table 11]

[0173]

Table 12

[0174] For the wavelength conversion sheets of Examples 1 to 3 and Comparative Example 1, Table 13 shows the initial peel strength (result of initial adhesion) and the peel strength after the long-term environmental test (result of adhesion over time).

[0175]

Table 13

[0176] Referring to Table 1, in the primer layer of Example 1, the sulfur ratio was low even at a depth of 0 nm (the peeling surface, the interface with the phosphor layer), and the sulfur ratio tended to decrease rapidly inside the depth of 23 nm. In the primer layer of Example 1, C PR / C QD at a depth of 23 nm was 0.01. C PR / C QD between depths of 2 nm and 11 nm was 0.06 and 0.05, respectively. Also, sulfur was not detected in the region of 171 nm and deeper (the region closer to the barrier layer). From these results, it can be understood that in the wavelength conversion sheet of Example 1, the penetration of components in the phosphor layer into the primer layer was suppressed.

[0177] Referring to Table 3, in the primer layer of Example 2, the sulfur ratio was low even at a depth of 0 nm, and the sulfur ratio tended to decrease rapidly inside the depth of 23 nm. In the primer layer of Example 2, C PR / C QD at a depth of 23 nm was 0.02. C PR / C QDAll of them were 0.05. Also, in the region of 115 nm and deeper, sulfur was not detected. From this result, it can be understood that in the wavelength conversion sheet of Example 2, penetration of the components in the phosphor layer into the primer layer was suppressed.

[0178] Referring to Table 5, in the primer layer of Example 3 as well, the ratio of sulfur was low even at a depth of 0 nm, and a tendency was seen that the ratio of sulfur decreased rapidly on the inner side rather than at a depth of 23 nm. In the primer layer of Example 3, C at a depth of 23 nm PR / C QD was 0.03. C between depths of 2 nm and 11 nm PR / C QD were all 0.04. Also, in the region of 170 nm and deeper, sulfur was not detected. From this result, it can be understood that in the wavelength conversion sheet of Example 3, penetration of the components in the phosphor layer into the primer layer was suppressed.

[0179] Referring to Table 7, in the primer layer of Comparative Example 1, the ratio of sulfur was high not only near the interface with the phosphor layer but also throughout the interior. As shown in Table 7, C at a depth of 27 nm PR / C QD was as high as 0.29. Also, in the region near the barrier layer between depths of 55 nm and 273 nm, the value of C PR / C QD became high. From this result, it can be understood 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.

[0180] Referring to Table 12, the coefficient of variation of the sulfur content in the primer layer of Comparative Example 1 is close to the coefficient of variation of the sulfur content in the phosphor layer. From this, it can be understood that Comparative Example 1 has little variation in the sulfur content in the thickness direction of the primer layer. In contrast, in Examples 1 to 3 shown in Tables 9 to 11, the coefficient of variation of the sulfur content in the phosphor layer is about the same as in Comparative Example 1, while the coefficient of variation of the sulfur content in the primer layer is very high. From the coefficient of variation of the sulfur content in the thickness direction of the primer layer, it can be understood that in all of the examples, the penetration of components in the phosphor layer into the primer layer was suppressed.

[0181] Referring to Table 13, the initial peel strength of the wavelength conversion sheets in both the examples and comparative examples was 5.0 N. However, after long-term environmental testing, the adhesion of the wavelength conversion sheet in Comparative Example 1 deteriorated significantly compared to the wavelength conversion sheets in Examples 1-3. Based on these results, it can be understood that suppressing the penetration of components in the phosphor layer into the primer layer suppresses degradation after long-term environmental testing. [Explanation of Symbols]

[0182] 10 (10a, 10b) Wavelength conversion sheet film 20 Base material layer 20-1 First substrate 20-2 Second substrate 22 Adhesive layer 30 Primer layer 40 Barrier layer 42. First barrier layer 44. Second barrier layer 50 Diffusion layer 60 Phosphor layer 100 Wavelength Conversion Sheet 110 Light source 120 Optical plate 121 Light guide plate 122 Light diffusing material 130 Reflector 140 Prism Sheets 200 Backlight 201 Edge-lit backlight 202 Direct-lit backlight

Claims

1. The device 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 aforementioned wavelength conversion sheet film comprises at least a substrate layer and a primer layer laminated together, wherein the primer layer is in contact with the phosphor layer. The phosphor layer and the primer layer contain element X, wherein element X is sulfur. 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 between the primer layer and the phosphor layer to 400 nm in the thickness direction of the phosphor layer is C ＱＤ (atomic%), and the proportion of element X in the primer layer obtained by X-ray photoelectron spectroscopy at any depth within the region between 20 nm and 40 nm in the thickness direction of the primer layer from the interface is C ＰＲ When (atomic%), C ＰＲ / C ＱＤ A wavelength conversion sheet that satisfies the condition of 0.10 or less.

2. The wavelength conversion sheet according to claim 1, 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 0.60 or more.

3. The wavelength conversion sheet according to claim 1 or claim 2, wherein the primer layer comprises a polyurethane resin and a polyester resin.

4. The wavelength conversion sheet according to claim 3, wherein the polyurethane resin is a resin obtained by the reaction of a polyfunctional isocyanate having a (meth)acrylic group with a hydroxyl group-containing compound.

5. The wavelength conversion sheet according to claim 4, wherein the polyurethane resin has a molar ratio of isocyanate groups to hydroxyl groups (NCO / OH ratio) of 1.1 or more.

6. The wavelength conversion sheet according to claim 4, wherein the primer layer further comprises a phenolic antioxidant.

7. The wavelength conversion sheet according to claim 1 or claim 2, further comprising a barrier layer between the substrate layer and the primer layer.

8. The wavelength conversion sheet according to claim 7, wherein the barrier layer comprises a first barrier layer and a second barrier layer, and the first barrier layer is an inorganic oxide layer.

9. The substrate layer comprises a first substrate and a second substrate, The barrier layer and the primer layer are formed on one surface of the first substrate. The wavelength conversion sheet according to claim 7, wherein the second substrate is bonded to the other surface of the first substrate via an adhesive layer.

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

11. A backlight comprising at least one light source that emits primary light, an optical plate disposed adjacent to the light source for light guidance or diffusion, and a wavelength conversion sheet disposed on the light-emitting side of the optical plate, wherein the wavelength conversion sheet is the wavelength conversion sheet described in claim 1 or claim 2.

12. A liquid crystal display device comprising a backlight and a liquid crystal panel as described in claim 11.

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