Barrier film, wavelength conversion sheet, backlight, and liquid crystal display device using the same

Abstract

To provide a barrier film which may reduce yellowishness and suppress temporal change in color tone when used for wavelength conversion sheets.SOLUTION: A barrier film for wavelength conversion sheets is provided, comprising an inorganic oxide layer A, an organic coating layer B, an inorganic oxide layer C, and an organic coating layer D provided in the described order on a light transmissive base material, where at least either of the inorganic oxide layer A and the inorganic oxide layer C contains silicon oxide. When refractive indices of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D are respectively defined as nA, nB, nC, and nD, and thicknesses of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D are respectively defined as tA, tB, tC, and tD, d1 represented by a formula 1 below is in a range of x±0.10 (x represents an odd-numbered integer between 5 and 19). Formula 1: d1=nA×tA / 112.5 nm+nB×tB / 112.5 nm+nC×tC / 112.5 nm+nD×tD / 112.5 nm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a barrier film, a wavelength conversion sheet using the same, a backlight, and a liquid crystal display device.

Background Art

[0002] With the development of personal computers (especially portable personal computers), the demand for liquid crystal display devices has been increasing. Recently, the penetration rate of household liquid crystal TVs has also been increasing, and furthermore, smartphones and tablet terminals are also becoming widely popular. For this reason, the market for liquid crystal display devices is further expanding. Such a liquid crystal display device generally has a configuration including a color filter, a liquid crystal cell, and a backlight. The intensity of light is controlled by the shutter function of the liquid crystal layer in the liquid crystal cell, and an image is displayed by separating the color of each pixel into the three primary colors of R, G, and B by the color filter.

[0003] As a light source for the backlight of a liquid crystal display device, a cold cathode tube (CCFL) has been conventionally used. However, from the viewpoints of low power consumption and less space, the light source of the backlight has been switched from a cold cathode tube to an LED. An LED generally used as a light source for a normal backlight uses a white LED formed by combining a blue LED and a YAG-based yellow phosphor. Such a white LED has a broad spectral distribution of emission wavelengths and is called pseudo-white.

[0004] On the other hand, in recent years, the development of a backlight using quantum dot technology has also been promoted. Quantum dots refer to semiconductor nanoparticles with a size of nanometers. The basic configuration of a backlight using quantum dots is a combination of a light source that generates primary light (such as a blue LED that emits blue light) and quantum dots.

[0005] Quantum dots are nano-sized compound semiconductor fine particles composed of, for example, semiconductor fine particles with a core of CdSe and a shell of ZnS, and ligands covering the periphery of the shell. Since the particle diameter of quantum dots is smaller than the Bohr radius of excitons in the compound semiconductor, the quantum confinement effect appears. Therefore, the light emission efficiency of quantum dots is higher than that of conventional phosphors (rare earth phosphors) using rare earth ions as activators, and a high light emission efficiency of 90% or more can be achieved. In addition, since the emission wavelength of quantum dots is determined by the band gap energy of the thus quantized compound semiconductor fine particles, an arbitrary emission wavelength, that is, an arbitrary emission spectrum can be obtained by changing the particle size of the quantum dots. A backlight combined with these quantum dots and a blue LED or the like is said to be able to achieve high light emission efficiency and high color purity (see, for example, Patent Documents 1 and 2).

[0006] While quantum dots have the above excellent characteristics, there is a problem that they are easily deteriorated by the influence of moisture, oxygen, etc. Therefore, it is preferable to protect both surfaces of the quantum dot-containing layer with barrier films. Patent Documents 3 and 4 propose a wavelength conversion sheet in which a quantum dot-containing layer is protected by a barrier film having a base material, an inorganic oxide layer, and an organic coating layer.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in liquid crystal display devices using the wavelength conversion sheets of Patent Documents 3 and 4, there were cases where the color tone of the image was more yellowish than expected and the expected color tone could not be obtained. In addition, in liquid crystal display devices using the wavelength conversion sheets of Patent Documents 3 and 4, there were cases where an image with a color tone different from the initial one was visually recognized while continuously in use. That is, in liquid crystal display devices using the wavelength conversion sheets of Patent Documents 3 and 4, when comparing the initial point in time with an arbitrary point in time, there were cases where the color tones were significantly different. Quantum dots are characterized by enhancing color purity. Therefore, as described above, the instability of the color tone of a liquid crystal display device using quantum dots impairs the characteristics of the liquid crystal display device and is an extremely important problem in terms of quality.

[0009] In view of the above problems, an object of the present invention is to provide a barrier film that can suppress yellowing and suppress changes in color tone over time when applied to a wavelength conversion sheet. Another object of the present invention is to provide a wavelength conversion sheet, a backlight, and a liquid crystal display device using the barrier film.

Means for Solving the Problems

[0010] As a result of intensive research to solve the above problems, the present inventors have found that by setting the refractive indices and thicknesses of the inorganic oxide layer and the organic coating layer constituting the barrier film to a specific relationship, it is possible to suppress the yellowing and changes in color tone of a wavelength conversion sheet or the like to which the barrier film is applied.

[0011] The present invention provides the following [1] to

[16] . [1] It has an inorganic oxide layer A, an organic coating layer B, an inorganic oxide layer C, and an organic coating layer D in this order on a light-transmissive substrate, At least one of the inorganic oxide layer A and the inorganic oxide layer C contains silicon oxide, The refractive indices of the light-transmissive substrate, the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D are defined as n0, n A , n B , n C , and n D , respectively, and when the thicknesses of the light-transmissive substrate, the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D are defined as t0, t A , t B , t C , and t D , respectively, n A and n C are smaller than n B and n D , and the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than any of the reflectances at the interfaces between the inorganic oxide layer A and the organic coating layer B, between the organic coating layer B and the inorganic oxide layer C, and between the inorganic oxide layer C and the organic coating layer D. Furthermore, d1 represented by the following formula (1) indicates a range of x ± 0.10 (where x is an odd integer from 5 to 19), A barrier film for a wavelength conversion sheet. (Formula 1) d1 = n A × t A / 112.5 nm + n B × t B / 112.5 nm + n C × t C / 112.5 nm + n D × t D / 112.5 nm [2] The barrier film according to [1], wherein d1 represented by the formula (1) indicates a range of x to x + 0.10 (where x is an odd integer from 5 to 19).

[0012] [3] Having a primer layer E on the side of the organic coating layer D opposite to the inorganic oxide layer C, the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than the reflectance at the interface between the organic coating layer D and the primer layer E, Define the refractive index of the primer layer E as n E and define the thickness of the primer layer E as t E When defined in this way, the barrier film according to [1], wherein d2 represented by the following formula (2) is in the range of y ± 0.10 (where y is an odd integer from 7 to 31). (Formula (2)) d2 = n A ×t A / 112.5 nm + n B ×t B / 112.5 nm + n C ×t C / 112.5 nm + n D ×t D / 112.5 nm + n E ×t E / 112.5 nm [4] The barrier film according to [3], wherein d2 represented by the formula (2) is in the range of y to y + 0.10 (where y is an odd integer from 7 to 31). [5] The barrier film according to [3] or [4], wherein n E / n D is 0.95 to 1.05. [6] The barrier film according to any one of [3] to [5], wherein t E is 70 nm to 1000 nm.

[0013] [7] The barrier film according to any one of [1] to [6], wherein t A and t C are each 20 nm to 160 nm. [8] The barrier film according to any one of [1] to [7], wherein t B and t D are each 70 nm to 600 nm. [9] The barrier film according to any one of [1] to [8], wherein t0 is 5 μm or more.

[10] The barrier film according to any one of [1] to [9], wherein both the inorganic oxide layer A and the inorganic oxide layer C contain silicon oxide.

[11] The barrier film according to any one of [1] to

[10] , wherein the organic coating layer B and the organic coating layer D contain polyvinyl alcohol.

[0014]

[12] A wavelength conversion sheet having a quantum dot-containing layer containing quantum dots and barrier films laminated on both sides of the quantum dot-containing layer, wherein the barrier films are laminated such that the surface opposite to the light-transmissive substrate of the barrier film according to any one of [1] to

[11] faces the quantum dot-containing layer side.

[13] The barrier film is the barrier film according to [1] or [2], the layer of the barrier film in contact with the quantum dot-containing layer is the organic coating layer D, and when the refractive index of the quantum dot-containing layer is defined as n Z The wavelength conversion sheet according to

[12] , which satisfies the following (i-1). (i-1)n D >n Z and d1 represented by the formula 1 is in the range of x±0.10 (where x is an odd integer from 5 to 19).

[14] The barrier film is the barrier film according to any one of [3] to [6], the layer of the barrier film in contact with the quantum dot-containing layer is the primer layer E, and when the refractive index of the quantum dot-containing layer is defined as n Z The wavelength conversion sheet according to

[12] , which satisfies the following (ii-1). (ii-1)n E >n Z and d2 represented by the formula 2 is in the range of y±0.10 (where y is an odd integer from 7 to 31).

[0015]

[15] A backlight including at least one light source that emits primary light, an optical plate disposed adjacent to the light source for light guiding 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 according to any one of

[12] to

[14] .

[16] A liquid crystal display device including a backlight and a liquid crystal panel, wherein the backlight is the backlight according to

[15] .

Advantages of the Invention

[0016] The barrier film of the present invention, as well as the wavelength conversion sheet, backlight, and liquid crystal display device using the same, can suppress yellowness and suppress changes in color tone over time.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described. In this specification, the notation “AA to BB” means AA or more and BB or less. In addition, in this specification, the refractive index of each layer shall mean the refractive index at a wavelength of 632.8 nm. The refractive index of each layer can be calculated, for example, by fitting the reflection spectrum measured by a reflection photometer and the reflection spectrum calculated from the optical model of the multilayer thin film using the Fresnel coefficient.

[0019] [Barrier film] The barrier film of the present invention has, in this order, an inorganic oxide layer A, an organic coating layer B, an inorganic oxide layer C, and an organic coating layer D on a light-transmissive substrate, at least one of the inorganic oxide layer A and the inorganic oxide layer C contains silicon oxide, defining the refractive indices of the light-transmissive substrate, the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D as n0, n A , n B , n C , and n D respectively, defining the thicknesses of the light-transmissive substrate, the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D as t0, t A , t B , t C , and t D respectively, when n A and n C are smaller than n B and n D , and the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than any of the reflectances at the interfaces between the inorganic oxide layer A and the organic coating layer B, between the organic coating layer B and the inorganic oxide layer C, and between the inorganic oxide layer C and the organic coating layer D, and further d1 represented by the following formula 1 indicates a range of x ± 0.10 (where x is an odd integer from 5 to 19), A barrier film for a wavelength conversion sheet. (Formula 1) d1 = n A × t A / 112.5 nm + n B × tB / 112.5 nm + n C × t C / 112.5 nm + n D × t D / 112.5 nm

[0020] Figures 1 and 2 are cross-sectional views showing embodiments of the barrier film (100) of the present invention. The barrier films (100) in Figures 1 and 2 have an inorganic oxide layer A (21), an organic coating layer B (31), an inorganic oxide layer C (22), and an organic coating layer D (32) in this order on a light-transmissive substrate (10). Further, the barrier film (100) in Figure 2 has a primer layer E (40) on the side opposite to the inorganic oxide layer C (22) of the organic coating layer D (32).

[0021] <Light-transmissive substrate> The light-transmissive substrate is not particularly limited as long as it is a resin film that does not impair the function of the wavelength conversion sheet when applied to the wavelength conversion sheet. Examples of the light-transmissive substrate include resin films formed from one or more resins selected from polyester, triacetyl cellulose (TAC), cellulose diacetate, cellulose acetate butyrate, polyamide, polyimide, polyethersulfone, polysulfone, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polyether ketone, acrylic, polycarbonate, polyurethane, and amorphous olefin (Cyclo-Olefin-Polymer: COP). Among these resin films, from the viewpoints of mechanical strength, dimensional stability, and heat resistance, a stretched film, particularly a biaxially stretched polyester film (for example, polyethylene terephthalate film, polyethylene naphthalate film) is preferable.

[0022] The light-transmissive substrate may be a single layer of a resin film or may have a plurality of resin films. When having a plurality of resin films, each resin film may be directly adhered or may be adhered via an adhesive layer.

[0023] The refractive index n0 of the light-transmissive substrate is not particularly limited as long as it satisfies the condition that "the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than any of the reflectances at the interfaces between the inorganic oxide layer A and the organic coating layer B, between the organic coating layer B and the inorganic oxide layer C, and between the inorganic oxide layer C and the organic coating layer D", but it is preferably 1.55 to 1.70, more preferably 1.57 to 1.65, and even more preferably 1.60 to 1.65. For example, the refractive index of a polyethylene terephthalate film is 1.636. Incidentally, just to be on the safe side, "the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than any of the reflectances at the interfaces between the inorganic oxide layer A and the organic coating layer B, between the organic coating layer B and the inorganic oxide layer C, and between the inorganic oxide layer C and the organic coating layer D" means satisfying the following relationships (1) to (3). (1) Reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance at the interface between the inorganic oxide layer A and the organic coating layer B (2) Reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance at the interface between the organic coating layer B and the inorganic oxide layer C (3) Reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance at the interface between the inorganic oxide layer C and the organic coating layer D

[0024] To easily satisfy the above-mentioned magnitude relationship of reflectances, it is preferable to select a light-transmissive substrate so that the absolute value of the difference (Δn A ) between n0 and n 0A becomes large. Δn 0A is preferably 0.15 or more, and more preferably 0.17 or more. The upper limit of Δn 0A is not particularly limited, but it is preferably 0.25 or less, and more preferably 0.22 or less. Also, it is preferable that n0 > n A .

[0025] In this specification, when the refractive index of one layer is defined as n1 and the refractive index of the other layer is defined as n2, the reflectance R at the interface between any two layers is represented by the following formula (i). R(%) = 100×(n1 - n2) 2 / (n1 + n2) 2 (Formula (i))

[0026] When the light-transmissive substrate has a plurality of resin films, the refractive index of the resin film on the side in contact with the inorganic oxide layer A may be used as the refractive index of the light-transmissive substrate, and the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A may be calculated.

[0027] The thickness t0 of the light-transmissive substrate is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more. By setting the thickness of the light-transmissive substrate to 5 μm or more, it is easy to improve the strength of the barrier film. In addition, by setting the thickness of the light-transmissive substrate to 5 μm or more, the optical path length of the light-transmissive substrate becomes sufficiently larger than the wavelength of visible light, so that the influence of the light-transmissive substrate on the waveform of the spectral transmittance spectrum of the barrier film can be easily ignored. Also, from the viewpoint of facilitating thinning and suppressing the intrusion of water vapor and oxygen from the ends, the thickness t0 of the light-transmissive substrate is preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less, even more preferably 50 μm or less, and even more preferably 25 μm or less.

[0028] In this specification, the thickness of each layer constituting the barrier film such as the thickness t0 of the light-transmissive substrate, and the thickness of the quantum dot-containing layer can be calculated from the average value of the thicknesses measured at 20 locations from an image of a cross-section taken using, for example, a scanning transmission electron microscope (STEM).

[0029] In this specification, when measuring various parameters such as the thickness, spectral transmittance, total light transmittance, color tone (x-value and y-value in the Yxy color system) of each layer, unless otherwise specified, the measurement shall be carried out in an atmosphere with a temperature of 23°C ± 5°C and a humidity of 40 - 65%RH. Furthermore, before measuring various parameters, the sample shall be exposed to the above atmosphere for 30 minutes or more.

[0030] In addition, in the constituent requirements shown in this specification, when multiple options for the upper limit and multiple options for the lower limit of a numerical value are respectively shown, one selected from the upper limit options and one selected from the lower limit options can be combined to form an embodiment of the numerical range. For example, in the case of the thickness t0 of the above light-transmissive substrate, embodiments of numerical ranges such as 5μm or more and 200μm or less, 5μm or more and 25μm or less, 8μm or more and 50μm or less, 10μm or more and 50μm or less, 10μm or more and 25μm or less, etc. can be cited.

[0031] When the light-transmissive substrate is composed of two resin films, the thickness of the first resin film closer to the inorganic oxide layer A is preferably 5μm to 50μm, more preferably 8μm to 25μm, and even more preferably 10μm to 20μm. When the first resin film has the above thickness, it is easy to improve the production efficiency of the inorganic oxide layer and also easy to improve the handling property. Also, the thickness of the second resin film farther from the inorganic oxide layer A is preferably 5μm to 150μm, more preferably 8μm to 100μm, and even more preferably 10μm to 50μm. When the second resin film has the above thickness, it is easy to improve the balance between the handling property and rigidity of the barrier film. When the light-transmissive substrate is composed of two resin films, the two resin films may be bonded together through an adhesive layer and then an inorganic oxide layer A or the like may be formed, or after forming an inorganic oxide layer A or the like on the first resin film, the second resin film may be bonded to the surface of the first resin film on the side opposite to the inorganic oxide layer A or the like through an adhesive layer. The thickness of the adhesive layer is preferably 3 μm to 100 μm, more preferably 3 μm to 50 μm, and even more preferably 4 μm to 8 μm. If the thickness of the adhesive layer is too thin, coating defects may occur, and if the thickness is too thick, insufficient curing may occur.

[0032] The light-transmissive substrate preferably has a total light transmittance of 80% or more in accordance with JIS K7361-1:1997, more preferably 85% or more, and even more preferably 87% or more.

[0033] On the surface of the light-transmissive substrate on the side where the inorganic oxide layer A is provided, a desired surface treatment may be performed in advance to improve adhesion and the like. Examples of the surface treatment include corona discharge treatment, ozone treatment, low-temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, and oxidation treatment using chemicals.

[0034] <Inorganic oxide layer> The barrier film of the present invention has an inorganic oxide layer A and an inorganic oxide layer C as the inorganic oxide layer. Thus, by having two inorganic oxide layers, the barrier properties of the barrier film against oxygen and water vapor can be improved, and the deterioration of the quantum dots can be easily suppressed. Also, when trying to improve the barrier properties with a single inorganic oxide layer, the thickness of the inorganic oxide layer becomes thick, and cracks are likely to occur in the inorganic oxide layer, making it difficult to maintain good barrier properties over a long period. However, by using two inorganic oxide layers, it is possible to suppress the increase in the thickness of each inorganic oxide layer, make cracks less likely to occur, and easily maintain good barrier properties over a long period. However, cracks or pinholes may occur even when the thickness of the inorganic oxide layer is reduced. However, even if cracks or pinholes occur in each of the two inorganic oxide layers, as long as the positions of the cracks or pinholes do not coincide in the plane direction, a predetermined barrier property can be ensured for the laminate. That is, it is preferable to use two inorganic oxide layers because it is easy to ensure a predetermined barrier property even when cracks or pinholes occur in the inorganic oxide layer.

[0035] The barrier film of the present invention requires that the refractive indices of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D be n A 、n B 、n C 、and n D When defined as such, n A and n C must be smaller than n B and n D . The inorganic oxide layer having a small refractive index preferably has a predetermined thickness in order to improve the barrier property. When the inorganic oxide layer has a predetermined thickness, it will affect the waveform of the spectral transmittance spectrum of the barrier film. That is, Equations 1 and 2 in this specification are based on the premise that the refractive index of the inorganic oxide layer is small and the inorganic oxide layer has a predetermined thickness.

[0036] The barrier film of the present invention requires that at least one of the inorganic oxide layer A and the inorganic oxide layer C contains silicon oxide. By including silicon oxide in at least one of the inorganic oxide layer A and the inorganic oxide layer C, it is possible to easily improve the light transmittance and productivity. Further, it is preferable that both the inorganic oxide layer A and the inorganic oxide layer C contain silicon oxide. Note that when the inorganic oxide layer contains silicon oxide, the b * a * b * value of the b * value in the L *It suppresses the increase in value.

[0037] When the inorganic oxide layer A and / or the inorganic oxide layer C contains silicon oxide, the content ratio of silicon oxide in each layer is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more on a mass basis.

[0038] The refractive index n of the inorganic oxide layer A A and the refractive index n of the inorganic oxide layer C C are each preferably 1.53 or less, more preferably 1.51 or less, still more preferably 1.49 or less, and even more preferably 1.47 or less. Also, n A and n C are each preferably 1.40 or more, more preferably 1.42 or more, and still more preferably 1.44 or more. Note that the refractive index of the inorganic oxide layer formed from silicon oxide is about 1.46. n A and n C By setting them within the above ranges, it is easier to satisfy the above-described relationship of the interface reflectance.

[0039] The refractive index n A and the refractive index n C are preferably substantially the same. Specifically, n A / n C is preferably 0.98 to 1.02, more preferably 0.99 to 1.01, and still more preferably 1.00.

[0040] The thickness t of the inorganic oxide layer A A , and the thickness t of the inorganic oxide layer C C are each preferably 20 nm or more, more preferably 50 nm or more, and still more preferably 70 nm or more. By setting t A and t C to 20 nm or more, it is easy to improve the barrier property. Also, t A and tC is preferably 220 nm or less, more preferably 180 nm or less, still more preferably 160 nm or less, yet more preferably 140 nm or less, and even more preferably 100 nm or less, respectively. t A and t C By setting and t to 220 nm or less, generation of scratches and cracks in the inorganic oxide layer A and the inorganic oxide layer C can be suppressed, and the color tone derived from the inorganic oxide can be easily suppressed. Also, t A and t C By setting and t to 220 nm or less, shortening of the period of the waveform of the spectral transmittance of the barrier film can be suppressed, and the effect of setting d1 in Formula 1 within a predetermined range can be easily exhibited.

[0041] t A and t C may be different values, but are preferably substantially the same. t A and t C being substantially the same means that t A / t C is 0.95 to 1.05, preferably 0.97 to 1.03, and more preferably 0.99 to 1.01.

[0042] The inorganic oxide layer can be formed, for example, by physical vapor deposition methods such as vacuum evaporation method, sputtering method, and ion plating method (Physical Vapor Deposition method, PVD method), or chemical vapor deposition methods such as plasma chemical vapor deposition method, thermal chemical vapor deposition method, and photo chemical vapor deposition method (Chemical Vapor Deposition method, CVD method). Among these, the vacuum evaporation method is preferred from the viewpoint of productivity (deposition rate).

[0043] <Organic coating layer> The barrier film of the present invention has an organic coating layer B and an organic coating layer D as the organic coating layers. By having an organic coating layer in combination with an inorganic oxide layer, the barrier property of the barrier film can be improved, and it is easy to suppress the deterioration of quantum dots. Further, since the organic coating layer has better flexibility than the inorganic oxide layer, the organic coating layers B and D can easily suppress the occurrence of scratches and cracks in the inorganic oxide layers A and C.

[0044] The organic coating layers B and D preferably contain at least one selected from a water-soluble polymer and a metal alkoxide compound. Further, the organic coating layers B and D more preferably contain at least one selected from water-soluble polymers among the water-soluble polymer and the metal alkoxide compound, and still more preferably contain at least one selected from water-soluble polymers and at least one selected from metal alkoxide compounds.

[0045] Examples of the water-soluble polymer include polyvinyl alcohol, polyvinyl pyrrolidone, and ethylene-vinyl alcohol copolymer. Among these, from the viewpoint of barrier properties, polyvinyl alcohol and ethylene-vinyl alcohol copolymer are preferable, and polyvinyl alcohol is more preferable. That is, the organic coating layers B and D preferably contain at least one selected from polyvinyl alcohol and ethylene-vinyl alcohol copolymer, and more preferably contain polyvinyl alcohol.

[0046] When the organic coating layers B and D contain a water-soluble polymer and a metal alkoxide compound, the content of the water-soluble polymer with respect to 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 still more preferably 8 parts by mass or more and 50 parts by mass or less.

[0047] Examples of the metal alkoxide compound include metal alkoxides, metal alkoxide hydrolyzates, and metal alkoxide polymers. A metal alkoxide is a compound represented by the general formula M(OR). n In the formula, M represents a metal such as Si, Ti, Al, and Zr, and R represents an alkyl group such as a methyl group and an ethyl group. Specific examples of the metal alkoxide include tetramethoxysilane, tetraethoxysilane, and isopropoxyaluminum.

[0048] The organic coating layer can be formed, for example, by applying a coating liquid containing components constituting the organic coating layer onto the inorganic oxide layer and drying it. The coating liquid may contain additives such as a silane coupling agent, a curing agent, and a dispersant.

[0049] The refractive index n of the organic coating layer B B and the refractive index n of the organic coating layer D D are each preferably at least 1.45, more preferably at least 1.50, and even more preferably at least 1.52. Also, the upper limit of n B and n D is each preferably at most 1.64, more preferably at most 1.60, and even more preferably at most 1.57.

[0050] The refractive index n B and the refractive index n D are preferably substantially the same. Specifically, n B / n D is preferably from 0.98 to 1.02, more preferably from 0.99 to 1.01, and even more preferably 1.00.

[0051] The thickness t of the organic coating layer B B , and the thickness t of the organic coating layer D D are each preferably at least 70 nm, more preferably at least 100 nm, and even more preferably at least 150 nm. By setting t B and t D to be at least 70 nm, the barrier property can be easily improved. Also, t B and tD Preferably, each has an upper limit of 600 nm or less, more preferably 480 nm or less, still more preferably 370 nm or less, still more preferably 300 nm or less, still more preferably 230 nm or less, and still more preferably 195 nm or less. t B and t D By setting t and t to 600 nm or less, the barrier film can be made thinner, the period of the spectral transmittance waveform of the barrier film can be shortened, and excessive swelling of the organic coating layer B and the organic coating layer D can be suppressed, making it easier to more effectively exhibit the effects when satisfying Formula 1 and Formula 2. Also, t B and t D If they are too thick, the stress generated when applying and drying the organic coating layer becomes large, and cracks may occur in the inorganic oxide layer due to this stress, resulting in a decrease in barrier properties. Therefore, by setting t B and t D to 600 nm or less, it is easier to achieve good initial barrier properties. t B and t D Examples of the embodiments within the range of t and t include, for example, 70 nm or more and 600 nm or less, 70 nm or more and 480 nm or less, 70 nm or more and 370 nm or less, 70 nm or more and 300 nm or less, 70 nm or more and 230 nm or less, 70 nm or more and 195 nm or less, 100 nm or more and 600 nm or less, 100 nm or more and 480 nm or less, 100 nm or more and 370 nm or less, 100 nm or more and 300 nm or less, 100 nm or more and 230 nm or less, 100 nm or more and 195 nm or less, 150 nm or more and 600 nm or less, 150 nm or more and 480 nm or less, 150 nm or more and 370 nm or less, 150 nm or more and 300 nm or less, 150 nm or more and 230 nm or less, 150 nm or more and 195 nm or less.

[0052] t B and t D and t may have different values, but are preferably substantially the same. t B and t D being substantially the same means that t B / t DIt means being 0.95 to 1.05, preferably 0.97 to 1.03, and more preferably 0.99 to 1.01.

[0053] <Refractive Index and Formula 1> The barrier film of the present invention has n A and n C being smaller than n B and n D and the interfacial reflectance satisfies the relationships (1) to (3) above, and further, d1 represented by the following formula 1 needs to be in the range of x ± 0.10 (where x is an odd integer from 5 to 19). (Formula 1) (Formula 1) d1 = n A ×t A / 112.5 nm + n B ×t B / 112.5 nm + n C ×t C / 112.5 nm + n D ×t D / 112.5 nm

[0054] Preferably, d1 represented by the above formula 1 is in the range of x ± 0.07 (where x is an odd integer from 5 to 19), more preferably in the range of x ± 0.05 (where x is an odd integer from 5 to 19), even more preferably in the range of x ± 0.03 (where x is an odd integer from 5 to 19), and still more preferably in the range of x ± 0.01 (where x is an odd integer from 5 to 19). Regarding d1 represented by the above formula 1, "x" is preferably an odd integer from 7 to 17, and more preferably an odd integer from 9 to 15.

[0055] First, the background for the inventors to bring the refractive index and d1 of formula 1 into a predetermined range will be explained. As shown in FIG. 3, the barrier films (100a, 100b) are disposed on both sides of the quantum dot-containing layer (50) and are used as components of the wavelength conversion sheet (200). In the backlight including the wavelength conversion sheet, light (generally, blue light centered at a wavelength of 450 nm) emitted from the primary light source of the backlight enters the light transmissive substrate (10) of the barrier film (100b) below the wavelength conversion sheet (200). When the light of the primary light source enters the light transmissive substrate (10) of the barrier film (100b) below the wavelength conversion sheet (200) in FIG. 3, most of the light passes through the light transmissive substrate (10), the inorganic oxide layer A (21), the organic coating layer B (31), the inorganic oxide layer C (22), and the organic coating layer D (32) and reaches the quantum dot-containing layer (50). Of the light of the primary light source that reaches the quantum dot-containing layer (50), the light that collides with the quantum dots is converted into light of a wavelength different from that of the primary light source (hereinafter, this light is referred to as L2). L2 includes, for example, green light and red light. On the other hand, of the light of the primary light source that reaches the quantum dot-containing layer (50), the light that does not collide with the quantum dots enters the organic coating layer D (32) of the upper barrier film (100a) as light of the wavelength of the primary light source (hereinafter, this light is referred to as L1). L1 includes, for example, blue light. Most of the light (L1 and L2) incident on the upper barrier film (100a) passes through the organic coating layer D (32), the inorganic oxide layer C (22), the organic coating layer B (31), the inorganic oxide layer A (21), and the light transmissive substrate (10) and goes toward a member (for example, a brightness enhancement sheet such as a prism sheet) disposed on the viewer side of the wavelength conversion sheet (200). The color tone of the liquid crystal display device to which the wavelength conversion sheet including the barrier film is applied is established by the balance between L1 and L2. Therefore, it is considered that the reason why the color tone of the liquid crystal display device changes over time is that the balance between L1 and L2 changes.

[0056] The inventors intensively studied the cause of the change in the balance between L1 and L2. First, it is considered that the light quantity of L2 gradually decreases as the quantum dots deteriorate. However, since the deterioration of the quantum dots is suppressed due to the presence of a barrier film or the like, the change in color cannot be explained only by the deterioration of the quantum dots. Also, when the primary light source deteriorates, not only L1 but also L2 relatively decreases, so it is unlikely to be caused by the deterioration of the primary light source. As a result of further intensive research, the inventors found that the color of the liquid crystal display device applying the wavelength conversion sheet including the barrier film changes due to the synergistic effect between the change in the transmittance of L1 of the upper barrier film 100a (≒ the change in the light quantity of L1 emitted from the upper barrier film) and the change in the light quantity of L2 due to the deterioration of the quantum dots. And the inventors found that the main cause of the change over time in the transmittance of L1 of the upper barrier film 100a (≒ the light quantity of L1 emitted from the upper barrier film 100a) is the swelling of the organic coating layer B and the organic coating layer D due to humidity.

[0057] Next, the technical significance of setting the refractive index and d1 in Formula 1 within a predetermined range will be explained. First, L1 passes through six interfaces before passing through the upper barrier film 100a. The six interfaces are the interface between the quantum dot-containing layer and the organic coating layer D (interface 1), the interface between the organic coating layer D and the inorganic oxide layer C (interface 2), the interface between the inorganic oxide layer C and the organic coating layer B (interface 3), the interface between the organic coating layer B and the inorganic oxide layer A (interface 4), the interface between the inorganic oxide layer A and the light-transmissive substrate (interface 5), and the interface between the light-transmissive substrate and the air (interface 6). The refractive index n of the quantum dot-containing layer Z is usually the refractive index n of the organic coating layer D Dis smaller. Therefore, the reflection at interface 1 is usually a fixed-end reflection. The transmittance (%) of L1 is roughly "100(%) - reflectance (%)". The reflectance of L1 must take into account the interference between the reflection at interface 1 and the reflection at other interfaces. Specifically, when the reflection at interface 1 decreases due to interference with the reflection at other interfaces, the transmittance of L1 increases, and conversely, when the reflection at interface 1 increases due to interference with the reflection at other interfaces, the transmittance of L1 decreases.

[0058] When considering the interference between the reflection at interface 1 (usually fixed end reflection) and the reflection at interfaces 2-6, it is necessary to consider the nature of the reflection at interfaces 2-6. In the present invention, n A and n C n B and n D Therefore, the reflection at interface 2 is a free end reflection, the reflection at interface 3 is a fixed end reflection, and the reflection at interface 4 is a free end reflection. In addition, in a normal design, the refractive index n of the inorganic oxide layer A is smaller than the refractive index n0 of the light-transmitting substrate. A is lower. Therefore, the reflection at interface 5 is a fixed-end reflection. In this way, the reflection at interfaces 2 to 5 is a mixture of free-end reflection and fixed-end reflection, but in the present invention, it is an essential requirement that the reflectance of interface 5 (the interface between the light-transmitting substrate and the inorganic oxide layer A) is higher than the reflectance of interfaces 2 to 4. Therefore, the fixed-end reflection at interface 5 has the greatest effect on the fixed-end reflection at interface 1. Finally, let us consider the reflection at the interface 6. Usually, the thickness of the light-transmitting substrate is designed to be sufficiently thicker than the wavelength of light. Therefore, the reflection at the interface 6 is negligible as a so-called thin film interference. From the above, the main reflection that should be considered as a reflection that interferes with the reflection at interface 1 (usually the fixed-end reflection) is the fixed-end reflection at interface 5.

[0059] Assuming that the reflections at Interface 1 and Interface 5 are both fixed - end reflections, for light with wavelength λ, when the following relationship of Equation x - 1 is satisfied, the reflection at Interface 5 weakens the reflection at Interface 1 and the reflectivity decreases. And the decrease in reflectivity means an increase in transmittance. Therefore, assuming that the reflections at Interface 1 and Interface 5 are both fixed - end reflections, the light with wavelength λ emitted from the quantum - dot - containing layer has the highest transmittance when the following relationship of Equation x - 1 is satisfied. 2×n A ×t A +2×n B ×t B +2×n C ×t C +2×n D ×t D =λ / 2 (Equation x - 1)

[0060] Equation x - 1 can be transformed into the following Equation x - 2. n A ×t A +n B ×t B +n C ×t C +n D ×t D =λ / 4 (Equation x - 2) From Equation x - 2, when it is assumed that the reflections at Interface 1 and Interface 5 are both fixed - end reflections, it can be said that the transmittance of light with wavelength λ is the highest when "n A ×t A +n B ×t B +n C ×t C +n D ×t D " satisfies "λ / 4". Also, because the spectral transmittance has periodicity, when it is assumed that the reflections at Interface 1 and Interface 5 are both fixed - end reflections, it can be said that the transmittance of light with wavelength λ is the highest when "n A ×t A +n B ×t B +n C ×t C +n D ×t D " is an odd multiple of "λ / 4". And, "n A ×tA +n B ×t B +n C ×t C +n D ×t D How many times the "」" is of "λ / 4" can be calculated by dividing the left side of Equation x - 2 by the right side. The central wavelength of the primary light of the backlight using quantum dots is approximately 450 nm. When λ is 450 nm, "λ / 4" in Equation x - 2 is "112.5 nm". That is, Equation 1 of the present invention is an equation representing how many times "n A ×t A +n B ×t B +n C ×t C +n D ×t D " is of "112.5 nm (λ / 4)". And, when it is assumed that the reflections at Interface 1 and Interface 5 are both fixed - end reflections, when d1 in Equation 1 is 2x + 1 (x is an integer of 0 or more), the transmittance of light with a wavelength of 450 nm becomes the highest, and when d1 in Equation 1 is 2x (x is an integer of 1 or more), the transmittance of light with a wavelength of 450 nm becomes the lowest. In other words, when it is assumed that the reflections at Interface 1 and Interface 5 are both fixed - end reflections, when d1 in Equation 1 is odd, the transmittance of light with a wavelength of 450 nm shows a peak, and when d1 in Equation 1 is even, the transmittance of light with a wavelength of 450 nm shows a bottom. The light with a wavelength of 450 nm can be regarded as L1 described above.

[0061] The reflection at Interface 1 is usually a fixed - end reflection, but when the reflection at Interface 1 is a free - end reflection, it can be considered as follows. In this case, the main reflection to be considered as interfering with the reflection at Interface 1, which is a free - end reflection, remains the fixed - end reflection at Interface 5. And in this case, when d1 in Equation 1 is 2x + 1 (x is an integer of 0 or more), the transmittance of light with a wavelength of 450 nm becomes the lowest, and when d1 in Equation 1 is 2x (x is an integer of 1 or more), the transmittance of light with a wavelength of 450 nm becomes the highest.

[0062] The barrier film of the present invention requires that the value of d1 in Formula 1 be x ± 0.10 (where x is an odd integer from 5 to 19). That is, the barrier film of the present invention indicates that the value of d1 is in the vicinity of an odd integer from 5 to 19. In other words, the barrier film of the present invention, in which the value of d1 is in the vicinity of an odd integer from 5 to 19, indicates that the waveform of the spectral transmittance spectrum of the light transmitted through the barrier film has a peak near 450 nm. Thus, by having the waveform of the spectral transmittance spectrum of the barrier film have a peak near 450 nm, it is possible to suppress a change in color tone when exposed to a high-humidity environment. The reason for such an effect is considered as follows. First, when the barrier film is exposed to a high-humidity environment, the organic coating layer of the barrier film swells. And when the organic coating layer swells, since the thickness of the organic coating layer increases, the waveform of the spectral transmittance of the barrier film shifts (mainly to the long-wavelength side). And although the change in the spectral transmittance of the barrier film is small near the peak or bottom, it tends to be large in the region away from the peak or bottom. Therefore, by setting the transmittance at a wavelength of 450 nm of the barrier film near the peak, it is considered that the change in the transmittance at 450 nm when the organic coating layer swells and the waveform of the spectral transmittance spectrum shifts can be suppressed (the reason for excluding the vicinity of the bottom and limiting it to the vicinity of the peak will be described later). Since the central wavelength of the primary light of the backlight using quantum dots is approximately 450 nm, suppressing the change in the transmittance at 450 nm of the barrier film means suppressing the change in the transmittance of the light (L1) that did not collide with the quantum dots among the light of the primary light source that reached the quantum dot-containing layer (50), and it is considered that the change in color tone of the backlight using quantum dots can be suppressed. In addition, in the wavelength region of L2 (green and red), since the period of the waveform of the spectral transmittance spectrum is longer than that of L1 (blue), it is less affected by the swelling of the organic coating layer.

[0063] As described above, the barrier film of the present invention can suppress a change in color tone due to a high-humidity environment by indicating that the value of d1 in Formula 1 is in the vicinity of an odd integer from 5 to 19. Even if the value of d1 is an odd integer, in the cases of 1 or 3, it means that the thickness of the inorganic oxide layer and / or the organic coating layer is thin. In this case, since the barrier property becomes insufficient, the color tone changes due to the deterioration of the quantum dots themselves. Also, when the value of d1 exceeds around 19, it means that the thickness of the inorganic oxide layer and / or the organic coating layer is thick. In this case, cracks occur in the inorganic oxide layer, or the swelling of the organic coating layer becomes excessive and the thickness of the organic coating layer changes greatly, etc., so that the change in color tone cannot be suppressed. Further, when the value of d1 exceeds around 19, the period of the spectral transmittance waveform becomes short, and it becomes difficult to suppress the change in color tone.

[0064] The spectral transmittance of the barrier film changes little not only near the peak but also near the bottom. Therefore, even when the value of d1 in Formula 1 is near an even integer, the change in color tone due to the high humidity environment can be suppressed within a predetermined range. However, when the inorganic oxide layer contains silicon oxide, the L * a * b * value of the b value in the color system * tends to increase. A film with a high b * value (a film that feels yellowish) is shunned from the viewpoint of the visibility of the image display device. And the fact that the value of d1 in Formula 1 is near an even integer (≒ the spectral transmittance of the barrier film shows a bottom at 450 nm) means that the transmittance of blue, which is the complementary color of yellow, becomes low, and the problem of yellowish color due to silicon oxide cannot be suppressed. Also, when the value of d1 in Formula 1 is greatly deviated from an odd integer, the transmittance of blue, which is the complementary color of yellow, becomes low, and it is difficult to suppress the problem of yellowish color due to silicon oxide. Therefore, from the viewpoint of suppressing yellowish color, in the present invention, it is an essential requirement that the value of d1 in Formula 1 indicates near an odd integer.

[0065] <Preferred Embodiment 1B> In addition, for the barrier film of the present invention, it is preferable that d1 represented by Formula 1 falls within the range of x to x + 0.10 (where x is an odd integer from 5 to 19), more preferably within the range of x to x + 0.07 (where x is an odd integer from 5 to 19), still more preferably within the range of x to x + 0.05 (where x is an odd integer from 5 to 19), even more preferably within the range of x to x + 0.03 (where x is an odd integer from 5 to 19), and most preferably within the range of x to x + 0.01 (where x is an odd integer from 5 to 19). Yes.

[0066] In Preferred Embodiment 1B, since d1 represented by Formula 1 is a value near an odd number, it can be said that the waveform of the spectral transmittance spectrum of the barrier film has a peak near 450 nm. Further, in Preferred Embodiment 1B, d1 represented by Formula 1 shows a value on the plus side from exactly an odd number. Therefore, in the barrier film satisfying Preferred Embodiment 1B, when the organic coating layer swells and the waveform of the spectral transmittance of the barrier film shifts to the long wavelength side, the transmittance at a wavelength of 450 nm will decrease. That is, in Preferred Embodiment 1B, when the organic coating layer swells, the transmittance of L1 decreases. On the other hand, the light (L2) converted by the quantum dots gradually decreases in light quantity due to the deterioration of the quantum dots. Therefore, in Preferred Embodiment 1B, since the light quantity of L2 decreases due to the deterioration of the quantum dots and the transmittance of L1 also decreases, the balance between L1 and L2 is less likely to be disrupted, which is preferable in that it can further suppress the change in color tone. In addition, in Preferred Embodiment 1B, "x" in d1 represented by Formula 1 is preferably an odd integer from 7 to 17, and more preferably an odd integer from 9 to 15.

[0067] <Other Preferred Embodiments> For the barrier film of the present invention, d represented by the following Formula 1-1 1-1 preferably falls within the range of x1 ± 0.10 (where x1 is an integer of 1 or more). In addition, for the barrier film of the present invention, d represented by the following Formula 1-2 1-2Preferably, it indicates the range of x2 ± 0.10 (where x2 is an integer of 1 or more). Further, the barrier film of the present invention has d represented by the following formula 1-3 1-3 Preferably, it indicates the range of x3 ± 0.10 (where x3 is an integer of 1 or more).

[0068] (Formula 1-1) d 1-1 = n D × t D / 112.5 nm (Formula 1-2) d 1-2 = n C × t C / 112.5 nm + n D × t D / 112.5 nm (Formula 1-3) d 1-3 = n B × t B / 112.5 nm + n C × t C / 112.5 nm + n D × t D / 112.5 nm

[0069] d represented by Formula 1-1 1-1 d represented by Formula 1-2 1-2 and d represented by Formula 1-3 1-3 By setting them within the above range, the effects based on Formula 1 can be more easily exhibited. d 1-1 More preferably, it indicates the range of x1 ± 0.07 (where x1 is an integer of 1 or more), still more preferably, it indicates the range of x1 ± 0.05 (where x1 is an integer of 1 or more), still more preferably, it indicates the range of x1 ± 0.03 (where x1 is an integer of 1 or more), and still more preferably, it indicates the range of x1 ± 0.01 (where x1 is an integer of 1 or more). d 1-2More preferably, it represents a range of x2 ± 0.07 (where x2 is an integer of 1 or more), more preferably a range of x2 ± 0.05 (where x2 is an integer of 1 or more), more preferably a range of x2 ± 0.03 (where x2 is an integer of 1 or more), and even more preferably a range of x2 ± 0.01 (where x2 is an integer of 1 or more). d 1-3 More preferably, it represents a range of x3 ± 0.07 (where x3 is an integer of 1 or more), more preferably a range of x3 ± 0.05 (where x3 is an integer of 1 or more), more preferably a range of x3 ± 0.03 (where x3 is an integer of 1 or more), and even more preferably a range of x3 ± 0.01 (where x3 is an integer of 1 or more).

[0070] <Primer layer> The barrier film of the present invention may have a primer layer E on the side opposite to the inorganic oxide layer C of the organic coating layer D. Having a primer layer at this position is preferable in that it can improve the adhesion between the barrier film and the quantum dot-containing layer. The primer layer is preferably disposed on the side opposite to the inorganic oxide layer C of the organic coating layer D and in contact with the organic coating layer D. Further, the primer layer is preferably disposed on the outermost layer of the barrier film.

[0071] 《Formula 2》 The barrier film of the present invention has a primer layer E on the side opposite to the inorganic oxide layer C of the organic coating layer D, and the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than the reflectance at the interface between the organic coating layer D and the primer layer E. Defining the refractive index of the primer layer E as n E and defining the thickness of the primer layer E as t E When defined as such, it is preferable that d2 represented by the following formula 2 represents a range of y ± 0.10 (where y is an odd integer from 7 to 31). (Formula 2) d2 = n A ×t A / 112.5nm + n B ×t B / 112.5nm + nC ×t C / 112.5nm + n D ×t D / 112.5nm + n E ×t E / 112.5nm

[0072] In Formula 2, it means that the reflectance of the interface satisfies the following relationships (1) to (4). (1) Reflectance of the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance of the interface between the inorganic oxide layer A and the organic coating layer B (2) Reflectance of the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance of the interface between the organic coating layer B and the inorganic oxide layer C (3) Reflectance of the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance of the interface between the inorganic oxide layer C and the organic coating layer D (4) Reflectance of the interface between the light-transmissive substrate and the inorganic oxide layer A > Reflectance of the interface between the organic coating layer D and the primer layer E

[0073] Preferably, d2 represented by the above Formula 2 indicates a range of y ± 0.07 (where y is an odd integer from 7 to 31), more preferably a range of y ± 0.05 (where y is an odd integer from 7 to 31), even more preferably a range of y ± 0.03 (where y is an odd integer from 7 to 31), and still more preferably a range of y ± 0.01 (where y is an odd integer from 7 to 31). Regarding d2 represented by the above Formula 2, "y" is preferably an odd integer from 9 to 27, more preferably an odd integer from 11 to 23, and even more preferably an odd integer from 13 to 21.

[0074] The technical idea of Formula 2 is generally the same as that of Formula 1. When the primer layer E is provided on the side opposite to the inorganic oxide layer C of the organic coating layer D, L1 passes through seven interfaces before passing through the upper barrier film 100a. The seven interfaces are the interface between the quantum dot-containing layer and the primer layer E (interface 1-1), the interface between the primer layer E and the organic coating layer D (interface 1-2), the interface between the organic coating layer D and the inorganic oxide layer C (interface 2), the interface between the inorganic oxide layer C and the organic coating layer B (interface 3), the interface between the organic coating layer B and the inorganic oxide layer A (interface 4), the interface between the inorganic oxide layer A and the light-transmissive substrate (interface 5), and the interface between the light-transmissive substrate and air (interface 6). Refractive index n of the quantum dot-containing layer Z is usually smaller than the refractive index n of the primer layer E E . Therefore, the reflection at interface 1-1 is usually a fixed-end reflection. When considering the interference between the reflection at interface 1-1 (usually a fixed-end reflection) and the reflections at interfaces 1-2, 2 to 6, it is necessary to examine the nature of the reflections at interfaces 1-2, 2 to 5. The reflections at interfaces 1-2, 2 to 5 are a mixture of free-end reflection and fixed-end reflection. However, in an embodiment where the reflectance at interface 5 (the interface between the light-transmissive substrate and the inorganic oxide layer A) is higher than the reflectances at interfaces 1-2, 2 to 4, the fixed-end reflection at interface 5 will have the greatest influence on the fixed-end reflection at interface 1. The reflection at interface 6 is a reflection that can be ignored as so-called thin-film interference. Therefore, the main reflection to be considered as interfering with the reflection at interface 1-1 (usually a fixed-end reflection) is the fixed-end reflection at interface 5. And as the optical distance of the fixed-end reflection at interface 5, it is necessary to consider the optical distance of the primer layer (n E ×t E ).

[0075] Assuming that the reflections at both Interface 1-1 and Interface 5 are fixed-end reflections, for light with wavelength λ, when the relationship of the following Equation y-1 is satisfied, the reflection at Interface 5 weakens the reflection at Interface 1-1, and the reflectance decreases. And the decrease in reflectance means an increase in transmittance. Therefore, assuming that the reflections at both Interface 1-1 and Interface 5 are fixed-end reflections, the light with wavelength λ emitted from the quantum dot-containing layer has the highest transmittance when the relationship of the following Equation y-1 is satisfied. 2×n A ×t A +2×n B ×t B +2×n C ×t C +2×n D ×t D +2×n E ×t E =λ / 2 (Equation y-1)

[0076] Equation y-1 can be transformed into the following Equation y-2. n A ×t A +n B ×t B +n C ×t C +n D ×t D +n E ×t E =λ / 4 (Equation y-2) From Equation y-2, when it is assumed that the reflections at both Interface 1-1 and Interface 5 are fixed-end reflections, it can be said that the transmittance of light with wavelength λ is the highest when "n A ×t A +n B ×t B +n C ×t C +n D ×t D +n E ×t E " = "λ / 4" is satisfied. Also, since there is periodicity in the spectral transmittance, when it is assumed that the reflections at both Interface 1-1 and Interface 5 are fixed-end reflections, "n A ×t A +n B ×t B +n C ×tC +n D ×t D +n E ×t E When "..." is an odd multiple of "λ / 4", it can be said that the transmittance of light with wavelength λ is the highest. And when "n A ×t A +n B ×t B +n C ×t C +n D ×t D +n E ×t E " is several times of "λ / 4" can be calculated by dividing the left side of Equation y - 2 by the right side. The central wavelength of the primary light of the backlight using quantum dots is approximately 450 nm. When λ is 450 nm, "λ / 4" in Equation y - 2 is "112.5 nm". That is, Equation 2 is an equation representing how many times "n A ×t A +n B ×t B +n C ×t C +n D ×t D +n E ×t E " is of "112.5 nm (λ / 4)". And, when it is assumed that the reflections at interfaces 1 - 1 and 5 are both fixed - end reflections, when d2 in Equation 2 is 2y + 1 (y is an integer of 0 or more), the transmittance of light with wavelength 450 nm is the highest, and when d2 in Equation 2 is 2y (y is an integer of 1 or more), the transmittance of light with wavelength 450 nm is the lowest. In other words, when it is assumed that the reflections at interfaces 1 - 1 and 5 are both fixed - end reflections, when d2 in Equation 2 is odd, the transmittance of light with wavelength 450 nm shows a peak, and when d2 in Equation 2 is even, the transmittance of light with wavelength 450 nm shows a bottom. The light with wavelength 450 nm can be regarded as L1 described above.

[0077] The reflection at interface 1 - 1 is usually a fixed - end reflection, but when the reflection at interface 1 - 1 is a free - end reflection, it can be considered as follows. In this case, the main reflection to be considered as interfering with the reflection of interface 1-1, which is a free-end reflection, must be the fixed-end reflection of interface 5. And in this case, when d2 in Equation 2 is 2y + 1 (y is an integer of 0 or more), the transmittance at a wavelength of 450 nm becomes the lowest, and when d2 in Equation 2 is 2y (y is an integer of 1 or more), the transmittance at a wavelength of 450 nm becomes the highest.

[0078] As described above, the technical idea of Equation 2 is generally the same as that of Equation 1. Therefore, by showing that the value of d2 in Equation 2 is in the vicinity of an odd integer from 7 to 31, it is possible to easily suppress the change in color tone in a high-humidity environment. Also, by showing that the value of d2 in Equation 2 is in the vicinity of an odd integer, it is possible to easily suppress yellowness. The reason why the value of d2 in Equation 2 is larger than d1 in Equation 1 is that the optical thickness of the primer layer E is effective. Even if the value of d2 is an odd integer, when it is in the range of 1 to 5, the thicknesses of the inorganic oxide layer, the organic coating layer, and the primer layer E become thin, and there may be a case where the barrier property and the adhesion to the quantum dot-containing layer decrease, which is not preferable. Also, when the value of d2 exceeds the vicinity of 31, it is not preferable in that cracks may easily occur in the inorganic oxide layer, the swelling of the organic coating layer may become excessive, or the barrier film may become thick. Also, when the value of d2 exceeds 31, the period of the spectral transmittance waveform becomes short, and it becomes difficult to suppress the change in color tone.

[0079] <Preferred Embodiment 2B> Further, in the barrier film of the present invention, it is preferable that d2 represented by Equation 2 shows a range of y to y + 0.10 (where y is an odd integer from 7 to 31), more preferably shows a range of y to y + 0.07 (where y is an odd integer from 7 to 31), still more preferably shows a range of y to y + 0.05 (where y is an odd integer from 7 to 31), still more preferably shows a range of y to y + 0.03 (where y is an odd integer from 7 to 31), and still more preferably shows a range of y to y + 0.01 (where y is an odd integer from 7 to 31).

[0080] In the preferred embodiment 2B, since d2 represented by Formula 2 is a value near an odd number, it can be said that the waveform of the spectral transmittance spectrum of the barrier film has a peak near 450 nm. Further, in the preferred embodiment 2B, d2 represented by Formula 2 shows a value on the plus side from exactly an odd number. Therefore, in the barrier film satisfying the preferred embodiment 2B, when the organic coating layer swells and the waveform of the spectral transmittance of the barrier film shifts to the long wavelength side, the transmittance at a wavelength of 450 nm will decrease. That is, in the preferred embodiment 2B, when the organic coating layer swells, the transmittance of L1 decreases. On the other hand, the light (L2) converted by the quantum dots gradually decreases in light quantity due to the deterioration of the quantum dots. Therefore, in the preferred embodiment 2B, since the light quantity of L2 decreases due to the deterioration of the quantum dots and the transmittance of L1 also decreases, the balance between L1 and L2 is less likely to be lost, which is preferable in that the change in color tone can be more suppressed. Further, in the preferred embodiment 2B, "y" in d2 represented by Formula 2 is preferably an odd integer from 9 to 27, more preferably an odd integer from 11 to 23, and even more preferably an odd integer from 13 to 21.

[0081] <Other Preferred Embodiments> The barrier film of the present invention has a d represented by the following Formula 2-1 2-1 preferably shows a range of y1 ± 0.10 (where y1 is an integer of 1 or more). Further, the barrier film of the present invention has a d represented by the following Formula 2-2 2-2 preferably shows a range of y2 ± 0.10 (where y2 is an integer of 1 or more). Further, the barrier film of the present invention has a d represented by the following Formula 2-3 2-3 preferably shows a range of y3 ± 0.10 (where y3 is an integer of 1 or more). Further, the barrier film of the present invention has a d represented by the following Formula 2-4 2-4 preferably shows a range of y4 ± 0.10 (where y4 is an integer of 1 or more).

[0082] (Formula 2-1) d 2-1 =n E ×t E / 112.5nm (Equation 2-2) d 2-2 =n D ×t D / 112.5nm + n E ×t E / 112.5nm (Equation 2-3) d 2-3 =n C ×t C / 112.5nm + n D ×t D / 112.5nm + n E ×t E / 112.5nm (Equation 2-4) d 2-4 =n B ×t B / 112.5nm + n C ×t C / 112.5nm + n D ×t D / 112.5nm + n E ×t E / 112.5nm

[0083] d represented by Equation 2-1 2-1 、d represented by Equation 2-2 2-2 、d represented by Equation 2-3 2-3 、and d represented by Equation 2-4 2-4 By setting d within the above range, the effects based on Equation 2 can be more easily exerted. d 2-1 Preferably indicates a range of y1 ± 0.07 (where y1 is an integer of 1 or more), more preferably indicates a range of y1 ± 0.05 (where y1 is an integer of 1 or more), even more preferably indicates a range of y1 ± 0.03 (where y1 is an integer of 1 or more), and even more preferably indicates a range of y1 ± 0.01 (where y1 is an integer of 1 or more). d 2-2It is more preferable to indicate a range of y2 ± 0.07 (where y2 is an integer of 1 or more), more preferably to indicate a range of y2 ± 0.05 (where y2 is an integer of 1 or more), more preferably to indicate a range of y2 ± 0.03 (where y2 is an integer of 1 or more), and even more preferably to indicate a range of y2 ± 0.01 (where y2 is an integer of 1 or more). d 2-3 It is more preferable to indicate a range of y3 ± 0.07 (where y3 is an integer of 1 or more), more preferably to indicate a range of y3 ± 0.05 (where y3 is an integer of 1 or more), more preferably to indicate a range of y3 ± 0.03 (where y3 is an integer of 1 or more), and even more preferably to indicate a range of y3 ± 0.01 (where y3 is an integer of 1 or more). d 2-4 It is more preferable to indicate a range of y4 ± 0.07 (where y4 is an integer of 1 or more), more preferably to indicate a range of y4 ± 0.05 (where y4 is an integer of 1 or more), more preferably to indicate a range of y4 ± 0.03 (where y4 is an integer of 1 or more), and even more preferably to indicate a range of y4 ± 0.01 (where y4 is an integer of 1 or more).

[0084] The refractive index n of the primer layer E E and the refractive index n of the organic coating layer D D The ratio (n E / n D ) is preferably 0.95 to 1.05, more preferably 0.97 to 1.03, and even more preferably 0.98 to 1.02.

[0085] The refractive index n of the primer layer E E Preferably has a lower limit of 1.47 or more, more preferably 1.52 or more, and even more preferably 1.55 or more. Also, the upper limit of n E is preferably 1.66 or less, more preferably 1.62 or less, and even more preferably 1.60 or less.

[0086] The thickness t of the primer layer E EIt is preferably from 70 to 1000 nm, more preferably from 100 to 500 nm, and even more preferably from 120 to 300 nm.

[0087] 《Composition》 The primer layer E preferably contains a resin component such as a polyurethane-based resin composition. The polyurethane-based resin easily improves the adhesion to the quantum dot-containing layer, and relaxes the stress generated when the quantum dot-containing layer is cured by ionizing radiation or heat, and plays a role in making the stress less likely to be transmitted to the inorganic oxide layer and the organic coating layer. Furthermore, the polyurethane-based resin can easily suppress the occurrence of cracks in the layer constituting the barrier film (particularly the inorganic oxide layer) by improving the elongation of the primer layer E.

[0088] Examples of the polyurethane-based resin composition include one-component or two-component polyurethane-based resin compositions obtained by the reaction of a polyfunctional isocyanate and a hydroxyl group-containing compound. Only one type of polyfunctional isocyanate and hydroxyl group-containing compound may be used, or a plurality of types may be used. Specifically, examples of the polyfunctional isocyanate include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, and polymethylene polyphenylene polyisocyanate, or aliphatic polyisocyanates such as hexamethylene diisocyanate and isophorone diisocyanate. Examples of the hydroxyl group-containing compound include polyether polyol, polyester polyol, polyester polyurethane polyol, and polyacrylate polyol. In the present invention, polyester polyurethane polyol is particularly preferred from the viewpoints of adhesion to the quantum dot-containing layer and durability. The polyester polyurethane polyol can be produced, for example, by the methods described in JP-A-2001-288408 and JP-A-2003-26996.

[0089] The content of the polyurethane-based resin composition is preferably 40% by mass or more, more preferably 70% by mass or more, based on the total amount of the primer layer E.

[0090] The primer layer E may further contain a silane coupling agent. By including the silane coupling agent, it is easier to improve the adhesion between the primer layer E and the organic coating layer D. One end of the molecule of the silane coupling agent, usually a functional group such as chloro, alkoxy, or acetoxy group, hydrolyzes to form a silanol group (Si-OH). Thereby, the resin composition of the primer layer E is modified by a covalent bond or the like to form a strong bond. Also, the organic functional groups such as vinyl, methacryloxy, amino-based, epoxy-based, or mercapto at the other end of the silane coupling agent can easily improve the adhesion between the primer layer E and the organic coating layer D, and between the primer layer E and the quantum dot-containing layer.

[0091] Examples of the silane coupling agent include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyl-tris(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, 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-aminopropylsilicone, etc. One or more of these can be used.

[0092] The content of the silane coupling agent is preferably 1% by mass or more, more preferably 3% by mass or more, based on the total amount of the primer layer E. When the content of the silane coupling agent is within the above range, the adhesion between the primer layer E and the organic coating layer D, and between the primer layer E and the quantum dot-containing layer can be further easily improved. In addition, in order to improve the extensibility of the primer layer E and suppress the occurrence of cracks in the primer layer E, the content of the silane coupling agent is preferably 30% by mass or less, more preferably 20% by mass or less, based on the total amount of the primer layer E.

[0093] The primer layer E may further contain a filler. The filler has a role of adjusting the viscosity of the coating liquid for forming the primer layer and enhancing the coating suitability and the like. As the filler, for example, calcium carbonate, barium sulfate, alumina white, silica, talc, glass frit, resin powder, etc. can be used.

[0094] The primer layer may further contain additives such as a stabilizer, a crosslinking agent, a lubricant, an ultraviolet absorber, and others, if necessary.

[0095] <Physical properties> <<Water vapor transmission rate>> The water vapor transmission rate of the barrier film is preferably 0.20 g / m 2 ·day or less, more preferably 0.15 g / m 2 ·day or less. The temperature and humidity conditions for measuring the water vapor transmission rate are 40°C and 90% RH. Also, before measuring the water vapor transmission rate, the sample for measurement is exposed to an atmosphere of 23°C ± 5°C and 40 - 65% RH for 30 minutes or more. The water vapor transmission rate can be measured, for example, with a water vapor transmission rate measuring device (trade name: PERMATRAN) manufactured by MOCON.

[0096] <<Oxygen transmission rate>> The oxygen permeability of the barrier film, as per JIS K7126-2:2006, is preferably 0.5 cc / m 2 ·day·atm or less. When measuring the oxygen permeability, the temperature and humidity conditions shall be 23°C and 90% RH. Also, before measuring the oxygen permeability, the sample for measurement shall be exposed to an atmosphere of 23°C ± 5°C and 40 - 65% RH for 30 minutes or more. The oxygen permeability can be measured, for example, using an oxygen permeability measuring device (trade name: OX-TRAN) manufactured by MOCON (Mocon method).

[0097] 《b* value》 The barrier film has an L * a * b * value of the b value in the color system * preferably 1.0 or less, more preferably -2.5 to 1.0, and even more preferably -2.0 to 0.8. L * a * b * The color system is based on the L * a * b * color system standardized by the International Commission on Illumination (CIE) in 1976 and is adopted in JIS Z8781-4:2013.

[0098] 《Total light transmittance》 The total light transmittance of the barrier film, as per JIS K7361-1:1997, is preferably 80% or more, more preferably 85% or more, and even more preferably 87% or more.

[0099] <Laminated structure> Examples of the laminated structure of the barrier film of the present invention include the following (1) and (2). In the following (1) and (2), " / " means the interface of the layers. (1) Light-transmissive substrate / Inorganic oxide layer A / Organic coating layer B / Inorganic oxide layer C / Organic coating layer D (2) Light-transmissive substrate / Inorganic oxide layer A / Organic coating layer B / Inorganic oxide layer C / Organic coating layer D / Primer layer E

[0100] As long as it does not inhibit the effects of the present invention, the barrier film may have layers other than those described above. In addition, as a laminated structure of the barrier film, the structure of (3) below is also conceivable. However, the laminated structure of (3) below is disadvantageous in terms of optical properties because it has a larger number of interfaces than (1) and (2) above, and the total thickness also increases. For this reason, the laminated structures of (1) and (2) above are preferable. (3) First light-transmissive substrate / Inorganic oxide layer A / Organic coating layer B / Inorganic oxide layer C / Organic coating layer D / Second light-transmissive substrate / Primer layer

[0101] The total thickness of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D is preferably 250 nm or more and 2000 nm or less, more preferably 300 nm or more and 1500 nm or less, and even more preferably 400 nm or more and 1000 nm or less. By setting the total thickness to 250 nm or more, the barrier property can be easily improved. Further, by setting the total thickness to 2000 nm or less, it is possible to suppress the period of the waveform of the spectral transmittance from becoming too short, and it is easy to exhibit the effect of satisfying Formula 1.

[0102] The total thickness of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, the organic coating layer D, and the primer layer E is preferably 270 nm or more and 2200 nm or less, more preferably 320 nm or more and 1700 nm or less, and even more preferably 420 nm or more and 1200 nm or less. By setting the total thickness to 270 nm or more, the barrier property can be easily improved. Further, by setting the total thickness to 2200 nm or less, it is possible to suppress the period of the waveform of the spectral transmittance from becoming too short, and it is easy to exhibit the effect of satisfying Formula 2.

[0103] <Manufacturing method> The barrier film can be manufactured, for example, by forming an inorganic oxide layer A, an organic coating layer B, an inorganic oxide layer C, and an organic coating layer D in this order on a light-transmissive substrate. When the barrier film has a primer layer E, the primer layer E may be formed on the organic coating layer D. As described above, the inorganic oxide layer A and the inorganic oxide layer C can be formed by a physical vapor deposition method such as a vacuum evaporation method or a chemical vapor deposition method such as a plasma chemical vapor deposition method. The organic coating layer B, the organic coating layer D, and the primer layer E can be formed by applying a coating solution in which the composition constituting each layer is dissolved or dispersed, drying, and curing as necessary.

[0104] <Use> The barrier film for a wavelength conversion sheet of the present disclosure can be used, for example, as a barrier film for a wavelength conversion sheet of a surface light source. Examples of the surface light source include a backlight source of a liquid crystal display device and a backlight source of an inspection device. That is, the barrier film for a wavelength conversion sheet of the present disclosure can be used for "a barrier film for a wavelength conversion sheet of a backlight source of a liquid crystal display device", "a barrier film for a wavelength conversion sheet of a backlight source of an inspection device", and the like. Furthermore, the barrier film for a wavelength conversion sheet of the present disclosure can also be used for "a barrier film for a wavelength conversion sheet for horticulture". Examples of the wavelength conversion sheet for horticulture include a sheet having a function of converting ultraviolet light into a wavelength suitable for plant growth. Examples of the wavelength suitable for plant growth include wavelengths suitable for photosynthesis. The wavelength conversion sheet for horticulture can be installed, for example, on the ceiling of horticultural facilities such as greenhouses and glass houses.

[0105] [Wavelength conversion sheet] The wavelength conversion sheet of the present invention is a wavelength conversion sheet having a quantum dot-containing layer containing quantum dots and barrier films laminated on both sides of the quantum dot-containing layer, wherein the barrier film is laminated such that the surface opposite to the light-transmissive substrate of the barrier film of the present invention described above faces the quantum dot-containing layer side.

[0106] FIG. 3 and FIG. 4 are cross-sectional views showing embodiments of the wavelength conversion sheet (200) of the present invention. The wavelength conversion sheets (200) in FIGS. 3 and 4 have a quantum dot-containing layer (50) containing quantum dots and barrier films (100a, 100b) laminated on both sides of the quantum dot-containing layer. Further, in the wavelength conversion sheets (200) of FIGS. 3 and 4, the surfaces of the barrier films (100a, 100b) opposite to the light-transmissive base materials (10) are laminated so as to face the quantum dot-containing layer (50) side.

[0107] The wavelength conversion sheet preferably has a vertically symmetric structure centered on the quantum dot-containing layer as shown in FIGS. 3 and 4. In other words, it is preferable to use barrier films having the same configuration for the barrier films laminated on both sides of the quantum dot-containing layer. By having such a configuration, strain can be evenly dispersed, the planarity of the wavelength conversion sheet can be easily improved, and the adhesion of each interface of the wavelength conversion sheet can be easily improved.

[0108] <Quantum dot-containing layer> The quantum dot-containing layer contains quantum dots and a binder resin.

[0109] A quantum dot is a semiconductor nanoparticle-sized fine particle, and due to the quantum confinement effect (quantum size effect) in which electrons and excitons are confined within a nanometer-sized small crystal, it exhibits specific optical and electrical properties, and is also called a semiconductor nanoparticle or a semiconductor nanocrystal. The quantum dot is a semiconductor nanoparticle-sized fine particle, and is not particularly limited as long as it is a material that produces a quantum confinement effect (quantum size effect). Examples of the quantum dot include semiconductor fine particles whose emission color is regulated by their own particle size and semiconductor fine particles having a dopant.

[0110] Quantum dots emit light of different colors depending on their particle size. For example, in the case of quantum dots composed only of a core made of CdSe, when the particle sizes are 2.3 nm, 3.0 nm, 3.8 nm, and 4.6 nm, the peak wavelengths of the fluorescence spectra are 528 nm, 570 nm, 592 nm, and 637 nm, respectively. That is, the particle size of the quantum dots that emit secondary light with a peak wavelength of 637 nm is 4.6 nm, and the particle size of the quantum dots that emit secondary light with a peak wavelength of 528 nm is 2.3 nm. The quantum dots preferably contain one or more selected from quantum dots that emit secondary light with a wavelength corresponding to red and quantum dots that emit secondary light with a wavelength corresponding to green, and more preferably contain quantum dots that emit secondary light with a wavelength corresponding to red and quantum dots that emit secondary light with a wavelength corresponding to green. The quantum dots may contain quantum dots other than quantum dots that emit secondary light with a wavelength corresponding to red and quantum dots that emit secondary light with a wavelength corresponding to green.

[0111] The content of the quantum dots is appropriately adjusted according to the thickness of the quantum dot-containing layer, the light recycling rate in the backlight, the desired color tone, etc. If the thickness of the quantum dot-containing layer is within the range described later, the content of the quantum dots is about 0.01 to 1.0 part by mass with respect to 100 parts by mass of the binder resin of the quantum dot-containing layer.

[0112] Specific examples of the material for the core of the quantum dots include II-VI group semiconductor compounds such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe; III-V group semiconductor compounds such as AlN, AlP, AlAs, AlSb, GaAs, GaP, GaN, GaSb, InN, InAs, InP, InSb, TiN, TiP, TiAs, and TiSb; and semiconductor compounds such as Si, Ge, and Pb, or semiconductor crystals containing such semiconductors. Further, semiconductor crystals containing semiconductor compounds containing three or more elements such as InGaP can also be used. Furthermore, as the quantum dots composed of semiconductor fine particles having a dopant, Eu is added to the above semiconductor compound. 3+ , Tb 3+ , Ag + , Cu + It is also possible to use a semiconductor crystal doped with a cation of a rare earth metal or a cation of a transition metal such as these. As the material for the core of the quantum dots, semiconductor crystals such as CdS, CdSe, CdTe, InP, and InGaP are suitable from the viewpoints of ease of fabrication, controllability of particle size for obtaining light emission in the visible region, and fluorescence quantum yield.

[0113] The quantum dots may be composed of one kind of semiconductor compound or two or more kinds of semiconductor compounds. For example, they may have a core-shell structure having a core composed of a semiconductor compound and a shell composed of a semiconductor compound different from the core. When using core-shell type quantum dots, as the semiconductor constituting the shell, by using a material having a higher band gap than the semiconductor compound forming the core so that excitons are confined in the core, the light emission efficiency of the quantum dots can be increased. Examples of such core-shell structures (core / shell) having a relationship of the magnitude of the band gap 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, InGaP / ZnSSe, and the like.

[0114] The size of the quantum dots may be appropriately controlled by the material constituting the quantum dots so that light of a desired wavelength can be obtained. As the particle size of the quantum dots decreases, the energy band gap increases. That is, as the crystal size decreases, the emission of the quantum dots shifts toward the blue side, that is, toward the high energy side. Therefore, by changing the size of the quantum dots, the emission wavelength can be adjusted over the entire wavelength range of the spectra in the ultraviolet region, visible region, and infrared region. Generally, the particle size (diameter) of the quantum dots is preferably in the range of 0.5 nm to 20 nm, particularly preferably in the range of 1 nm to 10 nm. Note that the narrower the size distribution of the quantum dots, the clearer the emission color can be obtained. The shape of the quantum dots is not particularly limited, and may be, for example, spherical, rod-shaped, disk-shaped, or other shapes. When the particle dots are not spherical, the particle size of the quantum dots can be taken as the value of a true sphere having the same volume. The quantum dots may be coated with a resin.

[0115] Examples of the binder resin for the quantum dot-containing layer include cured products of thermoplastic resins, thermosetting resin compositions, and cured products of radiation-curable resin compositions. Among these, from the viewpoint of durability, cured products of thermosetting resin compositions and cured products of radiation-curable resin compositions are preferable, and cured products of radiation-curable resin compositions are more preferable.

[0116] A thermosetting resin composition is a composition containing at least a thermosetting resin and is a resin composition that cures by heating. The thermosetting resin composition preferably contains a thiol compound described later in addition to the thermosetting resin, and more preferably contains a polyfunctional thiol compound. Examples of the thermosetting resin include acrylic resins, urethane resins, phenol resins, urea melamine resins, epoxy resins, unsaturated polyester resins, silicone resins, and the like. A curing agent is added to these curable resins to the thermosetting resin composition as necessary.

[0117] 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"). The ionizing radiation curable resin composition preferably contains, in addition to the ionizing radiation curable compound, a thiol compound described later, and more preferably contains a polyfunctional thiol compound.

[0118] Examples of the ionizing radiation curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl group, vinyl group, and allyl group, and epoxy group, oxetanyl group, etc. Among them, ethylenically unsaturated bond groups are preferred. Also, among the ethylenically unsaturated bond groups, (meth)acrylate group is preferred. Hereinafter, an ionizing radiation curable compound having a (meth)acryloyl group is referred to as a (meth)acrylate-based compound. That is, the binder resin preferably contains a cured product of a composition containing a (meth)acrylate-based compound. In this specification, "(meth)acrylate" refers to methacrylate and acrylate. Also, in this specification, "ionizing radiation" means those having energy quanta capable of polymerizing or crosslinking molecules among electromagnetic waves or charged particle beams. Usually, ultraviolet rays (UV) or electron beams (EB) are used, but in addition, electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams can also be used.

[0119] The radiation-curable compound may be a monofunctional radiation-curable compound having only one of the above functional groups, a polyfunctional radiation-curable compound having two or more of the above functional groups, or a mixture thereof. Among these, polyfunctional radiation-curable compounds are preferred, and polyfunctional (meth)acrylate compounds having two or more (meth)acryloyl groups are more preferred. That is, the binder resin preferably contains a cured product of a polyfunctional radiation-curable compound, and more preferably contains a cured product of a polyfunctional (meth)acrylate compound. Further, the binder resin preferably contains a cured product of a composition containing a polyfunctional radiation-curable compound and a thiol compound, and more preferably contains a cured product of a composition containing a polyfunctional (meth)acrylate compound and a thiol compound.

[0120] The polyfunctional (meth)acrylate compound may have an alkyleneoxy group. As the alkyleneoxy group, for example, an alkyleneoxy group having 2 to 4 carbon atoms is preferred, an alkyleneoxy group having 2 or 3 carbon atoms is more preferred, and an alkyleneoxy group having 2 carbon atoms is even more preferred.

[0121] The polyfunctional (meth)acrylate compound having an alkyleneoxy group may be a polyfunctional (meth)acrylate compound having a polyalkyleneoxy group containing a plurality of alkyleneoxy groups. When the polyfunctional (meth)acrylate compound has an alkyleneoxy group, the number of alkyleneoxy 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.

[0122] When the polyfunctional (meth)acrylate compound has an alkyleneoxy group, it preferably has a bisphenol structure. Thereby, the heat resistance of the cured product tends to be improved. Examples of the bisphenol structure include a bisphenol A structure and a bisphenol F structure, and among them, the bisphenol A structure is preferred. Among polyfunctional (meth)acrylate compounds having an alkyleneoxy 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 preferable, and ethoxylated bisphenol A type di(meth)acrylate is more preferable.

[0123] The radiation curable compound may be a monomer, an oligomer, a low molecular weight polymer, or a mixture thereof.

[0124] As described above, the thermosetting resin composition and the radiation curable resin composition preferably contain a thiol compound. The thiol compound is a compound having one or more units represented by R-SH (R is an organic group). In this specification, a compound having one unit represented by R-SH is called a monofunctional thiol compound, and a compound having two or more of the units is called a polyfunctional thiol compound.

[0125] The thiol compound may be a monofunctional thiol compound, but a polyfunctional thiol compound is preferable from the viewpoint of improving the strength of the quantum dot-containing layer. Among polyfunctional thiol compounds, a trifunctional thiol compound or a tetrafunctional thiol compound is more preferable.

[0126] The thiol compound undergoes a reaction (thiol-ene reaction) with a compound having a radically polymerizable functional group in the presence of a radical polymerization initiator. Since the thiol-ene reaction can suppress polymerization shrinkage, it relieves the stress generated during the curing of the quantum dot-containing layer. As a result, it is preferable in that the interlayer adhesion of the wavelength conversion sheet is more easily improved. In addition, the cured product obtained by the thiol-ene reaction is preferable in that it is easy to improve heat resistance. Furthermore, since the refractive index of the thiol compound (about 1.53) is higher than the refractive index of the polyfunctional (meth)acrylate-based compound (about 1.45), the degree of freedom in adjusting the refractive index of the quantum dot-containing layer can be increased. Incidentally, the following reaction is an example of the reaction between a monofunctional thiol compound and a compound having one radically polymerizable functional group. It is considered that the reaction product of a polyfunctional thiol compound and a compound having two or more radically polymerizable functional groups is likely to form a dendrimer structure. And when a dendrimer structure is formed, it is considered that the flexibility of the quantum dot-containing layer increases and the quantum dot-containing layer itself is likely to exhibit excellent stress relaxation properties. Examples of the radically polymerizable functional group include ethylenically unsaturated bond-containing groups such as (meth)acryloyl group, vinyl group, and allyl group.

[0127] [Chemical formula] [In the formula, R 1 and R 2 are organic groups.]

[0128] Specific examples of the monofunctional thiol compound 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, n-octyl 3-mercaptopropionate, and the like.

[0129] Specific examples of the polyfunctional thiol compound 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), 1,4-butanediol bis(3-mercaptobutyrate), 1,8-octanediol bis(3-mercaptopropionate), 1,8-octanediol bis(3-mercaptobutyrate), hexanediol bisthioglycolate, trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptoisobutyrate), trimethylolpropane tris(2-mercaptoisobutyrate), trimethylolpropane tristthioglycolate, tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate, trimethylolethane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptoisobutyrate), pentaerythritol tetrakis(2-mercaptoisobutyrate), dipentaerythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(2-mercaptopropionate), dipentaerythritol hexakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptoisobutyrate), dipentaerythritol hexakis(2-mercaptoisobutyrate), pentaerythritol tetrakisthioglycolate, dipentaerythritol hexakisthioglycolate, and the like.

[0130] In the 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 is preferably from 80:20 to 35:65, more preferably from 70:30 to 40:60.

[0131] When the ionizing radiation curable compound is an ultraviolet curable compound, the ionizing radiation curable composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator.

[0132] The quantum dot-containing layer may contain internal diffusion particles. As the internal diffusion particles, either organic particles or inorganic particles can be used. Examples of the organic particles include particles composed of polymethyl methacrylate, acrylic-styrene copolymer, melamine resin, polycarbonate, polystyrene, polyvinyl chloride, benzoguanamine-melamine-formaldehyde condensate, silicone resin, fluororesin, polyester, and the like. Examples of the inorganic fine particles include fine particles composed of silica, alumina, zirconia, titania, and the like. Examples of the shape of the internal diffusion particles include spherical, disk-shaped, rugby ball-shaped, amorphous, and the like. Also, the internal diffusion particles may be any of hollow particles, porous particles, and solid particles.

[0133] The content of the internal diffusion particles is preferably 1 to 40 parts by mass, more preferably 3 to 30 parts by mass, based on 100 parts by mass of the binder resin.

[0134] The average particle diameter of the internal diffusion particles is preferably 1 to 7 μm, more preferably 1 to 3 μm.

[0135] The thickness of the quantum dot-containing layer is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 30 to 130 μm.

[0136] The refractive index n of the quantum dot-containing layer Zis preferably from 1.40 to 1.55, more preferably from 1.43 to 1.52, and even more preferably from 1.46 to 1.50. Refractive index n of the quantum dot-containing layer Z is generally governed by the refractive index of the binder resin. This is because the quantum dot-containing layer has a low content of quantum dots, and even if an internal diffusing agent is contained, the particle size of the internal diffusing agent is larger than the wavelength of light and does not affect the refractive index of the layer.

[0137] <When the layer in contact with the quantum dot-containing layer is the organic coating layer D> When the layer in contact with the quantum dot-containing layer of the barrier film is the organic coating layer D, for example, the following embodiment (i-1) can be mentioned. Note that n Z means the refractive index of the quantum dot-containing layer.

[0138] (i-1) n D > n Z and d1 represented by the above formula 1 indicates a range of x ± 0.10 (where x is an odd integer from 5 to 19).

[0139] The embodiment of (i-1) has a peak in the waveform of the spectral transmittance spectrum of the barrier film near 450 nm. In (i-1), "x ± 0.10" is more preferably x ± 0.07, more preferably x ± 0.05, more preferably x ± 0.03, and even more preferably x ± 0.01. Also, in (i-1), "x" in d1 represented by formula 1 is preferably an odd integer from 7 to 17, and more preferably an odd integer from 9 to 15.

[0140] Also, the embodiment of (i-1) is preferably the following embodiment (i-1A). (i-1A) n D > n Z and d1 represented by the above formula 1 indicates a range of x to x + 0.10 (where x is an odd integer from 5 to 19).

[0141] In the embodiment of (i-1A), since the light quantity of L2 decreases due to the deterioration of the quantum dots and the transmittance of L1 also decreases, the balance between L1 and L2 is less likely to be disrupted, and the change in color tone can be more suppressed, which is preferable. Further, in the embodiment of (i-1A), the waveform of the spectral transmittance spectrum of the barrier film has a peak near 450 nm.

[0142] Also, in (i-1A), "x to x + 0.10" is more preferably x to x + 0.07, more preferably x to x + 0.05, more preferably x to x + 0.03, and more preferably x to x + 0.01. Also, in (i-1A), "x" in d1 represented by Formula 1 is preferably an odd integer from 7 to 17, and more preferably an odd integer from 9 to 15.

[0143] <When the layer in contact with the quantum dot-containing layer is the primer layer E> When the layer in contact with the quantum dot-containing layer of the barrier film is the primer layer E, for example, the following embodiment of (ii-1) can be cited. Note that n Z means the refractive index of the quantum dot-containing layer.

[0144] (ii-1) n E > n Z and d2 represented by the above formula 2 indicates a range of y ± 0.10 (where y is an odd integer from 7 to 31).

[0145] Among the embodiments of (ii-1), the waveform of the spectral transmittance spectrum of the barrier film has a peak near 450 nm. Note that in (ii-1), "y ± 0.10" is more preferably y ± 0.07, more preferably y ± 0.05, more preferably y ± 0.03, and more preferably y ± 0.01. In addition, in (ii-1), "y" in d2 represented by Formula 2 is preferably an odd integer from 9 to 27, more preferably an odd integer from 11 to 23, and even more preferably an odd integer from 13 to 21.

[0146] The embodiment of (ii-1) is preferably the following embodiment of (ii-1A). (ii-1A) n E > n Z and d2 represented by the formula 2 represents a range of y to y + 0.10 (where y is an odd integer from 7 to 31).

[0147] The embodiment of (ii-1A) is preferable in that the light quantity of L2 decreases due to the deterioration of the quantum dots, and the transmittance of L1 also decreases, so that the balance between L1 and L2 is less likely to be disrupted, and the change in color tone can be more suppressed. In addition, the embodiment of (ii-1A) has a peak in the waveform of the spectral transmittance spectrum of the barrier film near 450 nm.

[0148] In addition, in (ii-1A), "y to y + 0.10" is more preferably y to y + 0.07, more preferably y to y + 0.05, more preferably y to y + 0.03, and more preferably y to y + 0.01. In addition, in (ii-1A), "y" in d2 represented by Formula 2 is preferably an odd integer from 9 to 27, more preferably an odd integer from 11 to 23, and even more preferably an odd integer from 13 to 21.

[0149] [Backlight] The backlight of the present invention is a backlight including at least one light source that emits primary light, an optical plate disposed adjacent to the light source for light guiding 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 of the present invention described above.

[0150] As an example of the backlight 300 of the present invention, an edge-lit backlight 301 as shown in FIG. 5 or a direct-lit backlight 302 as shown in FIG. 6 can be mentioned.

[0151] The optical plate 220 used in the edge-lit backlight 301 of FIG. 5 is an optical member for guiding the primary light emitted by the light source 210, and is a so-called light guide plate 221. The light guide plate 221 is formed, for example, in a substantially flat plate shape molded such that at least one surface is a light incident surface and one surface substantially orthogonal thereto is a light emission surface.

[0152] The light guide plate is mainly made of a matrix resin selected from highly transparent resins such as polymethyl methacrylate. The light guide plate may be added with resin particles having a refractive index different from that of the matrix resin as necessary. Each surface of the light guide plate may have a complex surface shape instead of a uniform plane, and a dot pattern or the like may be provided.

[0153] The optical plate 220 used in the direct-lit backlight 302 of FIG. 6 is an optical member (light diffusion plate 222) having light diffusibility for making the pattern of the light source 210 less visible. Examples of the light diffusion plate 222 include a milky white resin plate having a thickness of about 1 to 3 mm.

[0154] In addition to the light source, optical plate, and barrier film described above, the edge-lit and direct-lit backlights may be provided with one or more members selected from a reflector, light diffusion film, prism sheet, brightness enhancement film (BEF), and reflective polarizing film (DBEF) according to the purpose. The reflector is disposed on the side opposite to the light emission surface side of the optical plate. The light diffusion film, prism sheet, brightness enhancement film, and reflective polarizing film are disposed on the light emission surface side of the optical plate. By adopting a configuration including one or more members selected from a reflector, light diffusion film, prism sheet, brightness enhancement film, and reflective polarizing film, etc., a backlight excellent in the balance of front luminance, viewing angle, etc. can be obtained.

[0155] In edge-lit type and direct-lit type backlights, the light source 210 is a light emitter that emits primary light, and it is preferable to use a light emitter that emits primary light having a wavelength corresponding to blue. The primary light having a wavelength corresponding to blue preferably has a peak wavelength in the range of 380 to 480 nm. The peak wavelength is more preferably 450 nm ± 7 nm, more preferably 450 nm ± 5 nm, more preferably 450 nm ± 3 nm, and more preferably 450 nm ± 1 nm. From the viewpoint that the device in which the backlight is installed can be simplified and miniaturized, the light source 210 is preferably an LED light source, and more preferably a blue single-color LED light source. The light source 210 is at least one, and from the viewpoint of emitting sufficient primary light, it is preferably a plurality.

[0156] For a backlight including a wavelength conversion sheet, with respect to the Yxy color system of the International Commission on Illumination (CIE), the difference in x value (Δx) and the difference in y value (Δy) before and after the following high-temperature and high-humidity test are preferably both 0.020 or less, and more preferably both 0.010 or less. By setting Δx and Δy to 0.020 or less, a change in color tone can be suppressed. High-temperature and high-humidity test: A test of exposing to an atmosphere of 60 °C and 90% RH for 1000 hours Note that the x value and y value after the high-temperature and high-humidity test are measured in an atmosphere of 23 °C ± 5 °C and 40 to 65% RH promptly after taking out the measurement sample from the environment of the high-temperature and high-humidity test.

[0157] [Liquid crystal display device] The liquid crystal display device of the present invention is a liquid crystal display device including a backlight and a liquid crystal panel, wherein the backlight is the backlight of the present invention described above.

[0158] 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 general structure in which the upper and lower sides of the liquid crystal layer are sandwiched between glass plates, specifically, those with display modes such as TN, STN, VA, IPS, and OCB can be used.

[0159] The liquid crystal display device further includes a polarizing plate, a color filter, and the like. General-purpose polarizing plates and color filters can be used.

[0160] The display image of the liquid crystal display device is color-displayed by white light irradiated from the backlight passing through the color filter. By using a color filter that matches the spectrum of the backlight by quantum dots, a display that is excellent in brightness and efficiency and generates very vivid colors can be realized.

Example

[0161] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited by these examples. Note that "parts" and "%" are based on mass unless otherwise specified.

[0162] 1. Measurement and evaluation Regarding the barrier films or wavelength conversion sheets of the examples and comparative examples, the following measurements and evaluations were performed. The results are shown in Tables 1 and 2.

[0163] 1-1. Water vapor permeability Regarding the barrier films of the examples and comparative examples, the value of water vapor permeability according to JIS K7129-2:2019 was measured. The measuring device used was the product named "PERMATRAN" manufactured by MOCON. The temperature and humidity conditions for measuring the water vapor permeability were 40°C and 90%RH. Also, before measuring the water vapor permeability, the sample for measurement was exposed to an atmosphere of 23°C ± 5°C and 40 - 65%RH for 30 minutes or more. The water vapor permeability measured in this way means the initial-stage water vapor permeability. Those with a water vapor permeability of 0.20 g / m 2 ·day or less are at the qualified level.

[0164] 1-2. Total light transmittance For the barrier films of the examples and comparative examples, the total light transmittance was measured. The measuring device used was a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). Those with a total light transmittance of 85% or more are at the passing level. Note that the total light transmittance was measured in an atmosphere of a temperature of 23°C ± 5°C and a humidity of 40 to 65% RH. Also, the sample was exposed to the above atmosphere for 30 minutes or more before measurement. The total light transmittance measured in this way means the total light transmittance at the initial stage.

[0165] 1-3.b * Value For the barrier films of the examples and comparative examples, L * a * b * The b value of the color system * was measured. The measuring device used was a spectrophotometer (product name: V670) manufactured by JASCO Corporation. Those with a b * value of 1.0 or less are at the passing level. Note that the b * value was measured in an atmosphere of a temperature of 23°C ± 5°C and a humidity of 40 to 65% RH. Also, the sample was exposed to the above atmosphere for 30 minutes or more before measurement. The b * value measured in this way means the b * value at the initial stage.

[0166] 1-4. Spectral transmittance For the barrier films of Example 1 and Comparative Example 1, with the surface opposite to the light-transmissive substrate as the light incident surface, the spectral transmittance in the wavelength range of 380 to 780 nm was measured (measurement wavelength interval; 1 nm). The measuring device used was a spectrophotometer (product name: V670) manufactured by JASCO Corporation, and the following were used as accessory units, etc. · Accessory unit; integrating sphere unit (manufactured by JASCO Corporation, product number: ISN-723) · Light source; deuterium lamp (190 to 350 nm), halogen lamp (330 to 2700 nm) · Measurement spot diameter: 2 to 20 mm The spectral transmittance of the barrier film of Example 1 is shown in Fig. 7, and the spectral transmittance of the barrier film of Comparative Example 1 is shown in Fig. 8. Further, as a reference example, the spectral transmittance of the barrier film obtained by removing the primer layer from the barrier film of Example 1 is shown in Fig. 9, and the spectral transmittance of the barrier film obtained by removing the primer layer from the barrier film of Comparative Example 1 is shown in Fig. 10. Note that in Figs. 7 to 10, the horizontal axis represents the wavelength (unit: "nm"), and the vertical axis represents the transmittance ("%"). The spectral transmittance was measured in an atmosphere of 23°C ± 5°C and 40 to 65% RH. Further, the sample was exposed to the above atmosphere for 30 minutes or more before measurement. The spectral transmittance measured in this way means the spectral transmittance at the initial stage.

[0167] 1-5.Δx, Δy <Preparation of a direct-lit backlight for measurement> A commercially available liquid crystal television (manufactured by VIZIO, PQ65-F1) equipped with a direct-lit backlight was disassembled, and the direct-lit backlight was taken out. The direct-lit backlight is equipped with a direct-lit blue LED having an emission center wavelength of 450 nm and a full width at half maximum of 20 nm as a light source. On the light-emitting side of the light source, a light diffusion plate, a wavelength conversion sheet containing a quantum dot layer, a prism sheet, and a reflective polarizing plate (brightness enhancement film, manufactured by 3M, DBEF (registered trademark)) are arranged in this order. Further, a reflective sheet is provided on the side opposite to the light-emitting side of the light source. The wavelength conversion sheet in the direct-lit backlight was changed to the wavelength conversion sheets of the examples and comparative examples to obtain a "direct-lit backlight for measuring the x value and y value at the initial stage". Note that the wavelength conversion sheets of the examples and comparative examples were exposed to an atmosphere of 23°C ± 5°C and 40 to 65% RH for 30 minutes or more before being incorporated into the direct-lit backlight. In addition, the wavelength conversion sheet in the direct-lit backlight was changed to the wavelength conversion sheets of the examples and comparative examples that had undergone a high-temperature and high-humidity test (a test of exposing to an atmosphere of 60°C and 90% RH for 1000 hours) to obtain a "direct-lit backlight for measuring the x value and y value after the high-temperature and high-humidity test". The operation of incorporating the wavelength conversion sheets of the examples and comparative examples that had undergone the high-temperature and high-humidity test into the direct-lit backlight was promptly performed in an atmosphere of 23°C ± 5°C and 40 to 65% RH. Then, for the direct - type backlight for measurement, measurements were carried out under the following measurement environment. <x - value and y - value at the initial stage> The direct - type backlight for measuring the x - value and y - value at the initial stage was lit. In a dark - room environment, the x - value and y - value in the Yxy color system of the International Commission on Illumination (CIE) were measured from the front direction 500 mm away. The measurement atmosphere was a temperature of 23°C ± 5°C and a humidity of 40 - 65%RH. Also, the sample was exposed to the above - mentioned atmosphere for 30 minutes or more before measurement. The measuring device used was a spectro - radiometer (product name: SR - 3AR) manufactured by Topcon Technohouse Co., Ltd. <x - value and y - value after the high - temperature and high - humidity test> The direct - type backlight for measuring the x - value and y - value after the high - temperature and high - humidity test was lit. In a dark - room environment, the x - value and y - value in the Yxy color system of the International Commission on Illumination (CIE) were measured from the front direction 500 mm away. The measurement atmosphere was a temperature of 23°C ± 5°C and a humidity of 40 - 65%RH. The measuring device used was a spectro - radiometer (product name: SR - 3AR) manufactured by Topcon Technohouse Co., Ltd. <Δx, Δy> The difference (Δx) between the x - value at the initial stage and the x - value after the high - temperature and high - humidity test, and the difference (Δy) between the y - value at the initial stage and the y - value after the high - temperature and high - humidity test were calculated. The qualified level is when both Δx and Δy are 0.020 or less.

[0168] 2. Preparation of quantum dot dispersion In a glove box purged with nitrogen so that the oxygen concentration was 300 ppm or less, quantum dots and amino - modified silicone were mixed at the following composition ratios and stirred with a magnetic stirrer for 4 hours while heating in a water bath at 90°C. Then, it 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. · 0.9 parts by mass of quantum dots (Emission peak: 540 nm, manufacturing number: 748056, manufactured by Sigma - Aldrich Co., LLC) · 0.9 parts by mass of quantum dots (Emission peak: 630 nm, manufacturing number: 790206, manufactured by Sigma - Aldrich Co., LLC) · 99 parts by mass of amino-modified silicone (manufactured by Genesee, product number: GP-344, viscosity: 670 mPa·s)

[0169] 3. Preparation of barrier film and preparation of wavelength conversion sheet [Example 1] Silicon oxide was deposited by vacuum evaporation on one surface of a biaxially stretched PET film (refractive index n0: 1.636, thickness t0: 12 μm) to form an inorganic oxide layer A (refractive index n A : 1.457, thickness t A : 20 nm). Next, the following coating solution for forming an organic coating layer was applied by gravure printing on the inorganic oxide layer A and heat-treated at 180°C for 60 seconds to form an organic coating layer B (refractive index n B : 1.55, thickness t B : 160 nm). Next, silicon oxide was deposited by vacuum evaporation on the organic coating layer B to form an inorganic oxide layer C (refractive index n C : 1.457, thickness t C : 20 nm). Next, the following coating solution for forming an organic coating layer was applied by gravure printing on the inorganic oxide layer C and heat-treated at 180°C for 60 seconds to form an organic coating layer D (refractive index n D : 1.55, thickness t D : 160 nm). Next, the following coating solution for forming a primer layer was applied by gravure printing on the organic coating layer D and heat-treated at 80°C for 60 seconds to form a primer layer E (refractive index n E : 1.575, thickness t E : 143 nm), and the barrier film of Example 1 was obtained. Note that two barrier films having the same configuration were produced.

[0170] <Preparation of coating solution for forming organic coating layer> A solution A was prepared by mixing water, isopropyl alcohol, and 0.5N hydrochloric acid (pH 2.2), and while cooling tetraethoxysilane to 10°C, mixing them. Separately, a 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 an organic coating layer (solid content: 5% by mass). In the coating solution for forming an organic coating layer, the mass ratio of tetraethoxysilane to polyvinyl alcohol is 29:4.

[0171] <Coating solution for forming a primer layer> · 50 parts by mass of polyester polyurethane polyol (Hydroxyl value: 62 mg KOH / g, solid content 20% by mass) · 1 part by mass of a silane coupling agent (3-glycidoxypropylmethyldimethoxysilane) · 1 part by mass of a silica filler (Average particle size 5 μm) · 1 part by mass of a curing agent (1,6-hexamethylene diisocyanate, solid content 35%) · 50 parts by mass of a solvent (Methyl ethyl ketone)

[0172] On the surface of one of the two barrier films prepared above on the primer layer side, a quantum dot-containing layer coating solution with the following formulation was applied, dried, and a laminate A was obtained by forming a quantum dot-containing layer without irradiation with ionizing radiation. Next, after laminating the surface of laminate A on the side of the quantum dot-containing layer without irradiation with ionizing radiation and the surface of the primer layer side of the other barrier film so that they face each other, ultraviolet rays were irradiated to promote the curing of the ionizing radiation curable resin composition of the quantum dot-containing layer, and the wavelength conversion sheet of Example 1 was obtained. The thickness of the quantum dot-containing layer is 100 μm and the refractive index is 1.48.

[0173] <Quantum dot-containing layer coating solution> · 58.11 parts by mass of a polyfunctional acrylate-based compound (Ethoxylated bisphenol A diacrylate; trade name "ABE-300" of Shin-Nakamura Chemical Co., Ltd.) · 38.74 parts by mass of a polyfunctional thiol compound (Pentaerythritol tetrakis(3-mercaptopropionate); trade name "PEMP" of SC Organic Chemicals Co., Ltd.) · 0.5 part by mass of a photoinitiator (trade name "Omnirad TPO H" of IGM Resins B.V.) · 1.61 parts by mass of the quantum dot dispersion prepared in the above "2" · 0.79 part by mass of acetic acid · 0.25 part by mass of titanium oxide (trade name "Ti-Pure R-706" of Chemours Co., Ltd.; particle size 0.36 μm)

[0174] [Examples 2 to 7] Barrier films and wavelength conversion sheets of Examples 2 to 7 were obtained in the same manner as in Example 1, except that the thicknesses of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, the organic coating layer D, and the primer layer E were changed to the values shown in Table 1.

[0175] [Example 8] Barrier films and wavelength conversion sheets of Example 8 were obtained in the same manner as in Example 1, except that the primer layer E was not formed on the organic coating layer D.

[0176] [Comparative Examples 1 to 11] Barrier films and wavelength conversion sheets of Comparative Examples 1 to 11 were obtained in the same manner as in Example 1, except that the thicknesses of the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, the organic coating layer D, and the primer layer E were changed to the values shown in Table 2.

[0177] [Comparative Example 12] Barrier films and wavelength conversion sheets of Comparative Example 12 were obtained in the same manner as in Example 1, except that the thicknesses of the inorganic oxide layer A and the organic coating layer B were changed to the values shown in Table 2, the primer layer E was formed on the organic coating layer B, and the inorganic oxide layer C and the organic coating layer D were not formed.

[0178] [Comparative Example 13] The thicknesses of the inorganic oxide layer A, the organic coating layer B, and the inorganic oxide layer C were changed to the values shown in Table 2, and a primer layer E was formed on the inorganic oxide layer C. A barrier film and a wavelength conversion sheet of Comparative Example 13 were obtained in the same manner as in Example 1, except that the organic coating layer D was not formed.

[0179]

Table 1

[0180]

Table 2

[0181] As is clear from the results in Table 1, it was confirmed that the barrier film of the example can suppress yellowness and the change in color over time when applied to the wavelength conversion sheet. On the other hand, from the results in Table 2, it was confirmed that the barrier film of the comparative example cannot suppress yellowness and / or the change in color over time when applied to the wavelength conversion sheet. Also, from the comparison between FIG. 7 and FIG. 8, it was confirmed that by making d2 represented by Formula 2 in the vicinity of an odd integer, the spectral transmittance of the barrier film can be made to peak near 450 nm. Further, from the comparison between FIG. 9 and FIG. 10, it was confirmed that by making d1 represented by Formula 1 in the vicinity of an odd integer, the spectral transmittance of the barrier film can be made to peak near 450 nm.

Explanation of Symbols

[0182] 10: Light-transmissive substrate 21: Inorganic oxide layer A 22: Inorganic oxide layer C 31: Organic coating layer B 32: Organic coating layer D 40: Primer layer 50: Quantum dot-containing layer 100: Barrier film 100a: Barrier film 100b: Barrier film 200: Wavelength conversion sheet 210: Light source 220: Optical plate 221: Light guide plate 222: Diffusion plate 230: Reflector 240: Prism sheet 300: Backlight 301: Edge-lit backlight 302: Direct-lit backlight

Claims

1. It has an inorganic oxide layer A, an organic coating layer B, an inorganic oxide layer C, and an organic coating layer D in this order on a light-transmissive substrate, At least one of the inorganic oxide layer A and the inorganic oxide layer C contains silicon oxide, The refractive indices of the light-transmissive substrate, the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D are defined as n ０ , n Ａ , n Ｂ , n Ｃ , and n Ｄ respectively, When the thicknesses of the light-transmissive substrate, the inorganic oxide layer A, the organic coating layer B, the inorganic oxide layer C, and the organic coating layer D are defined as t ０ , t Ａ , t Ｂ , t Ｃ , and t Ｄ respectively, n Ａ and n Ｃ are smaller than n Ｂ and n Ｄ , and The reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than any of the reflectances at the interfaces between the inorganic oxide layer A and the organic coating layer B, between the organic coating layer B and the inorganic oxide layer C, and between the inorganic oxide layer C and the organic coating layer D. Furthermore, d represented by the following formula 1 １ indicates a range of x ± 0.10 (where x is an odd integer from 5 to 19), A barrier film for a wavelength conversion sheet. (Formula 1) d １ = n Ａ × t Ａ / 112.5 nm + n Ｂ × t Ｂ / 112.5 nm + n Ｃ × t Ｃ / 112.5 nm + n Ｄ × t Ｄ / 112.5 nm

2. d represented by the formula 1 １ The barrier film according to claim 1, wherein the range is from x to x + 0.10 (where x is an odd integer from 5 to 19). **Claim 3** having a primer layer E on the side opposite to the inorganic oxide layer C of the organic coating layer D, the reflectance at the interface between the light-transmissive substrate and the inorganic oxide layer A is greater than the reflectance at the interface between the organic coating layer D and the primer layer E, defining the refractive index of the primer layer E as n Ｅ and defining the thickness of the primer layer E as t Ｅ when defined, d represented by the following formula 2 ２ shows a range of y ± 0.10 (where y is an odd integer from 7 to 31), The barrier film according to claim 1. (Formula 2) d ２ = n Ａ × t Ａ / 112.5 nm + n Ｂ × t Ｂ / 112.5 nm + n Ｃ × t Ｃ / 112.5 nm + n Ｄ × t Ｄ / 112.5 nm + n Ｅ × t Ｅ / 112.5 nm **Claim 4** d represented by the formula 2 ２ shows a range of y to y + 0.10 (where y is an odd integer from 7 to 31), the barrier film according to claim 3 **Claim 5** n Ｅ / n Ｄ is 0.95 to 1.05, the barrier film according to claim 3 or 4. **Claim 6** t Ｅ is 70 nm to 1000 nm, the barrier film according to any one of claims 3 to 5. **Claim 7** t Ａ and t ＣThe barrier film according to any one of claims 1 to 6, wherein each is 20 nm to 220 nm.

8. t Ｂ and t Ｄ The barrier film according to any one of claims 1 to 7, wherein each is 70 nm to 600 nm.

9. t ０ The barrier film according to any one of claims 1 to 8, wherein t is 5 μm or more.

10. The barrier film according to any one of claims 1 to 9, wherein both the inorganic oxide layer A and the inorganic oxide layer C contain silicon oxide.

11. The barrier film according to any one of claims 1 to 10, wherein the organic coating layer B and the organic coating layer D contain polyvinyl alcohol.

12. A wavelength conversion sheet having a quantum dot-containing layer containing quantum dots and a barrier film laminated on both sides of the quantum dot-containing layer, wherein the barrier film is laminated such that the surface opposite to the light-transmissive substrate of the barrier film according to any one of claims 1 to 11 faces the quantum dot-containing layer side.

13. The barrier film is the barrier film according to claim 1 or 2, the layer in contact with the quantum dot-containing layer of the barrier film is the organic coating layer D, and when the refractive index of the quantum dot-containing layer is defined as n Ｚ The wavelength conversion sheet according to claim 12, which satisfies the following (i-1). (i-1) n Ｄ > n Ｚ and d represented by the formula 1 １ indicates a range of x ± 0.10 (where x is an odd integer from 5 to 19).

14. The barrier film is the barrier film according to any one of claims 3 to 6, the layer in contact with the quantum dot-containing layer of the barrier film is the primer layer E, and the refractive index of the quantum dot-containing layer is n Ｚ The wavelength conversion sheet according to claim 12, which satisfies the following (ii-1) when defined as (ii-1) n Ｅ > n Ｚ and d represented by the formula 2 ２ indicates a range of y ± 0.10 (where y is an odd integer from 7 to 31).

15. In a backlight including at least one light source that emits primary light, an optical plate disposed adjacent to the light source for light guiding or diffusion, and a wavelength conversion sheet disposed on the light emitting side of the optical plate, the backlight wherein the wavelength conversion sheet is the wavelength conversion sheet according to any one of claims 12 to 14.

16. A liquid crystal display device including a backlight and a liquid crystal panel, wherein the backlight is the backlight according to claim 15.

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