Wavelength conversion member for backlight and method for manufacturing same

Abstract

To provide a wavelength conversion member for a backlight capable of, in particular, solving a problem of quantum dot agglomeration and a problem of using a scattering agent, reducing deterioration of light conversion efficiency, and improving light conversion efficiency of a resin molding containing a quantum dot, and to provide a manufacturing method thereof and a wavelength conversion member.SOLUTION: A wavelength conversion member for a backlight of the present invention includes a plurality of laminated resin layers. At least one resin layer contains a quantum dot, and the plurality of resin layers are integrated by a coextrusion molding.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wavelength conversion member for a backlight and a method for manufacturing the same. [Background technology]

[0002] Quantum dots are nanoparticles composed of hundreds to thousands of atoms and with a particle size of several to tens of nanometers. Quantum dots are also called fluorescent nanoparticles, semiconductor nanoparticles, or nanocrystals.

[0003] The peak emission wavelength of quantum dots can be varied by changing the particle size and composition of the nanoparticles, and therefore can be adjusted to a desired wavelength. Quantum dots can be dispersed in a resin and used as a wavelength conversion material. For example, Patent Document 1 describes a film in which quantum dots are dispersed in a resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-167320 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the film disclosed in Patent Document 1 involves laminating films together, which requires complicated work and also poses the problem of a tendency for light conversion efficiency to decrease.

[0006] The present invention has been made in consideration of these points, and in particular, aims to provide a wavelength conversion member for a backlight that can improve the light conversion efficiency of a resin molded body containing quantum dots, and a method for manufacturing the same. [Means for solving the problem]

[0007] The wavelength conversion member for a backlight of the present invention comprises a plurality of resin layers laminated together, at least one of the resin layers contains quantum dots, and the plurality of resin layers are integrated by co-extrusion molding, The resin layer has a three-layer structure consisting of a middle layer containing the quantum dots, and upper and lower layers formed above and below the middle layer that do not contain the quantum dots, the upper and lower layers containing a light scattering agent, there being no adhesive layer at the interface between the middle layer and the upper layer and the interface between the middle layer and the lower layer, the resin layers being directly bonded together, and the concentration of quantum dots in the entire resin layer being 0.05% or more and 1.5% or less. The intermediate layer contains the quantum dots having a core / shell structure, PMMA or COP, and zinc stearate. It is characterized by: [Effects of the Invention]

[0008] According to the wavelength conversion member for backlight of the present invention, by integrally molding by co-extrusion, a complicated manufacturing process is not required and the light conversion efficiency can be improved.

[0009] Furthermore, by using the wavelength conversion member for backlights of the present invention, it is possible to manufacture a highly efficient wavelength conversion member using quantum dots.

[0010] Furthermore, according to the method for manufacturing a wavelength conversion member for a backlight of the present invention, it is possible to manufacture the wavelength conversion member without a complicated lamination step. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a cross-sectional view of a wavelength conversion member for a backlight in the first embodiment. [Figure 2] 2A and 2B are schematic diagrams of quantum dots according to this embodiment. [Figure 3] FIG. 10 is a cross-sectional view of a wavelength conversion member for a backlight according to a second embodiment. [Figure 4] FIG. 10 is a cross-sectional view of a wavelength conversion member for a backlight according to a third embodiment. [Figure 5]FIG. 10 is a cross-sectional view of a wavelength conversion member for a backlight according to a fourth embodiment. [Figure 6] 3 is a flowchart showing a manufacturing process of a wavelength conversion member for a backlight in the present embodiment. [Figure 7] 10 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 9. [Figure 8] 10 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 10. [Figure 9] 11 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 11. [Figure 10] 12 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 12. [Figure 11] 13 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 13. [Figure 12] 10 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 14. [Figure 13] 10 is an enlarged photograph of a cross section of a quantum dot-containing resin film in Example 15. [Figure 14] 10 is a spectrum of the quantum dot-containing resin film in Example 9. [Figure 15] 10 is a spectrum of a quantum dot-containing resin film in Example 10. [Figure 16] 11 is a spectrum of a quantum dot-containing resin film in Example 11. [Figure 17] 13 is a spectrum of the quantum dot-containing resin film in Example 12. [Figure 18] 17 shows the spectrum of the quantum dot-containing resin film in Example 12 (measured by turning Example 12 upside down as measured in FIG. 17). [Figure 19] 13 is a spectrum of a quantum dot-containing resin film in Example 13. [Figure 20] 13 is a spectrum of the quantum dot-containing resin film in Example 14. [Figure 21]13 is a spectrum of the quantum dot-containing resin film in Example 14. [Figure 22] 15 is a spectrum of a quantum dot-containing resin film in Example 15. [Figure 23] 10 is a spectrum of the quantum dot-containing resin film in Example 16. [Figure 24] 13 is a spectrum of the quantum dot-containing resin film in Example 17. [Figure 25] 16 is a spectrum of the quantum dot-containing resin film in Example 18. [Figure 26] 10 is a spectrum of the quantum dot-containing resin film in Example 19. [Figure 27] 1 shows the spectrum of the quantum dot-containing resin film in Example 12 (measured without BEF). [Figure 28] 27 shows the spectrum of the quantum dot-containing resin film in Example 12 (measured without BEF) (measured by turning Example 12 measured in FIG. 27 upside down). [Figure 29] 1 shows the spectrum of the quantum dot-containing resin film in Example 14 (measured without BEF). [Figure 30] 29 shows the spectrum of the quantum dot-containing resin film in Example 14 (measured without BEF) (measured by turning Example 14 measured in FIG. 29 upside down). DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention (hereinafter abbreviated as "embodiment") will be described in detail below. Note that the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0013] FIG. 1 shows a cross-sectional view of a quantum dot-containing resin film according to a first embodiment. Here, a "film" is defined as a flexible sheet. A "sheet" generally refers to a structure in which the thickness is small relative to the length and width. In particular, the length L, width W, and thickness T of a quantum dot-containing resin film or sheet are not limited, and the dimensions vary depending on the product. For example, the film may be used as a backlight for a large product such as a television, or as a backlight for a small mobile device such as a smartphone. Therefore, the size is determined according to the product.

[0014] In the following description, the term "quantum dot-containing resin film" will be used, but it can also be interpreted as "quantum dot-containing resin sheet."

[0015] As shown in Fig. 1, the quantum dot-containing resin film 1 has, for example, a three-layer film structure. The middle layer 1b shown in Fig. 1 is a layer containing quantum dots (QD). The quantum dots will be described.

[0016] Quantum dots have fluorescent properties due to band-edge emission, and exhibit quantum size effects due to their particle size.

[0017] Quantum dots refer to nanoparticles with a particle size of about several nanometers to several tens of nanometers. For example, quantum dots are formed of CdS, CdSe, ZnS, ZnSe, ZnSeS, ZnTe, ZnTeS, InP, AgInS2, CuInS2, etc., or quantum dots with a structure in which these quantum dots serve as cores and are covered with a shell. Because Cd is toxic and its use is restricted in various countries, it is preferable that quantum dots do not contain Cd.

[0018] As shown in Figure 2A, it is preferable that a large number of organic ligands 11 are coordinated to the surface of the quantum dots 10. This makes it possible to suppress aggregation of the quantum dots 10, thereby enabling the desired optical properties to be exhibited. There are no particular limitations on the ligands that can be used in the reaction, but the following ligands are representative examples: Aliphatic primary amine, oleylamine: C 18 H 35 NH2, stearyl (octadecyl)amine: C 18 H 37 NH2, dodecyl(lauryl)amine: C 12 H 25 NH2, decylamine: C 10 H 21 NH2, Octylamine: C8H 17 NH2 Fatty acids, oleic acid: C 17 H 33 COOH, stearic acid: C 17 H 35 COOH, palmitic acid: C 15 H 31 COOH, myristic acid: C 13 H 27 COOH, Lauryl (dodecanoic) acid: C 11 H 23 COOH, Decanoic acid: CH 19 COOH, octanoic acid: CH 15 COOH Thiol, octadecanethiol: C 18 H 37 SH, hexanedecanethiol: C 16 H 33 SH, tetradecanethiol: C 14 H 29 SH, dodecanethiol: C 12 H 25 SH, decanethiol: C 10 H 21 SH, Octanethiol: CH 17 SH Phosphine series, trioctylphosphine: (C8H 17 )3P, triphenylphosphine: (C6H5)3P, tributylphosphine: (C4H9)3P Phosphine oxide series, trioctylphosphine oxide: (C8H 17 )3P=O, triphenylphosphine oxide: (C6H5)3P=O, tributylphosphine oxide: (C4H9)3P=O

[0019] The quantum dot 10 shown in FIG. 2B has a core-shell structure having a core 10a and a shell 10b covering the surface of the core 10a. As shown in FIG. 2B, it is preferable that a large number of organic ligands 11 are coordinated to the surface of the quantum dot 10. The core 10a of the quantum dot 10 shown in FIG. 2B is the nanoparticle shown in FIG. 2A. Therefore, the core 10a is formed of, for example, one of the materials listed above. The material of the shell 10b is not particularly limited, but it is preferably formed of zinc sulfide (ZnS), for example. Like the core 10a, it is preferable that the shell 10b does not contain cadmium (Cd).

[0020] The shell 10b may be in a state of being solid-solution on the surface of the core 10a. In Fig. 2B, the boundary between the core 10a and the shell 10b is shown by a dotted line, but this means that it does not matter whether the boundary between the core 10a and the shell 10b can be confirmed by analysis or not.

[0021] The quantum dots 10 contained in the intermediate layer 1b are not limited to one type, but may contain two or more types of QDs with different fluorescent wavelengths as required.

[0022] The middle layer 1b is formed from a resin composition in which quantum dots 10 are dispersed. The upper layer 1a, the middle layer 1b, and the lower layer 1c are all resin layers, and it is preferable that an amorphous resin is used for the resin layers. The amorphous resin is not particularly limited, but a resin with high transparency is used. Generally, a resin with a total light transmittance of 85% or more is preferable, but this is not particularly limited. Examples of amorphous resins that can be used include cyclic polyolefin polymer (COP), cyclic polyolefin copolymer (COC), polystyrene (PS), acrylic resin, polycarbonate (PC), modified polyphenylene ether (PPE), polyethylene terephthalate (PET), ethylene vinyl alcohol (EVAL), and polymethylpentene (PMP). Examples of highly transparent semi-crystalline resins that can be used include melt-extrusion moldable resins such as polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF).

[0023] The combination of amorphous resins used in this embodiment is not particularly limited, as it is determined according to the physical properties and functions required for the component.

[0024] Furthermore, as the amorphous resin that constitutes the resin molding in which the quantum dots are dispersed, acrylic resin, homopolymer (COP) or copolymer (COC) of cyclic olefin resin, polyethylene terephthalate (PET), or polycarbonate (PC) is preferred from the viewpoint of the dispersibility of the quantum dots in the resin and the fluorescence intensity after dispersion.

[0025] The upper layer 1a and the lower layer 1c shown in FIG. 1 are resin layers that do not contain quantum dots 10 and serve as protective layers for the middle layer 1b. The upper layer 1a and the lower layer 1c are formed from the resin materials listed above. The upper layer 1a and the lower layer 1c can be formed on the outer surface of the middle layer 1b using, for example, an acrylic resin, to protect the middle layer 1b from external damage. Alternatively, the upper layer 1a and the lower layer 1c can be formed on the outer surface of the middle layer 1b using, for example, polyethylene terephthalate resin (PET) or ethylene vinyl alcohol (EVAL), to function as a barrier layer against water and oxygen. Alternatively, the upper layer 1a and the lower layer 1c can be formed on the outer surface of the middle layer 1b using, for example, PET, polycarbonate (PC), cyclic polyolefin (COP), or cyclic polyolefin copolymer (COC), to make the film less susceptible to cracking and improve the film's handling properties.

[0026] Furthermore, the outer layers (upper layer 1a and lower layer 1c) formed above and below the middle layer 1b containing the quantum dots 10 are also used to flatten the film and adjust the total thickness of the film.

[0027] The upper layer 1a and the lower layer 1c do not necessarily have to be formed to the same thickness, and do not necessarily have to be made of the same resin material. The upper layer 1a and the lower layer 1c may have a functionally asymmetric structure.

[0028] Furthermore, the upper layer 1a or the lower layer 1c, or the upper layer 1a and the lower layer 1c, may contain a fluorescent material other than quantum dots, such as a fluorescent pigment or a fluorescent dye.

[0029] The quantum dot-containing resin film 1 shown in Fig. 1 is formed by co-extrusion molding a resin layer containing quantum dots 10 (middle layer 1b) and resin layers not containing quantum dots 10 (upper layer 1a and lower layer 1c). That is, there are no adhesive layers at the interface between middle layer 1b and upper layer 1a, and at the interface between middle layer 1b and lower layer 1c, and the resin layers are directly bonded together. This allows the quantum dot-containing resin film 1 to be appropriately thinned and also increases the light conversion efficiency.

[0030] 1, a resin layer containing quantum dots can be used as the upper layer 1a or the lower layer 1c, thereby making it possible to distribute the quantum dots unevenly in the film thickness direction.

[0031] The quantum dot-containing resin film 2 of the second embodiment shown in Figure 3 has a three-layer film structure consisting of a middle layer 2b containing quantum dots 10, and an upper layer 2a and a lower layer 2c which do not contain quantum dots 10 and are formed above and below the middle layer 2b.

[0032] The upper layer 2a and the lower layer 2c of the quantum dot-containing resin film 2 each contain an additive. One or more types of additives are contained. The type of additive is not limited, but examples of additives include light scattering agents such as silica (SiO2) and zinc oxide (ZnO), lubricants such as talc and metal soap, antiblocking agents, and reinforcing agents such as glass fiber and beads, which can be added to impart various functions. Furthermore, the upper layer 1a and the lower layer 1c may contain a fluorescent material other than quantum dots, such as a fluorescent pigment or fluorescent dye. Note that the upper layer 1a and the lower layer 1c do not necessarily have to contain the same additives.

[0033] In the quantum dot-containing resin film 3 of the third embodiment shown in Fig. 4, quantum dots are contained in both the upper layer 3a and the middle layer 3b. The lower layer 3c is a resin layer that does not contain quantum dots. The quantum dots contained in the upper layer 3a and the quantum dots contained in the middle layer 3b can be of different types. The lower layer 3c may also contain a phosphor other than quantum dots, such as a fluorescent pigment or fluorescent dye.

[0034] For example, the upper layer 3a may contain red-emitting quantum dots and the middle layer 3b may contain green-emitting quantum dots. Alternatively, the middle layer 3b may contain red-emitting quantum dots and the upper layer 3a may contain green-emitting quantum dots.

[0035] For example, when the quantum dot-containing resin film 3 is used as a wavelength conversion member, in order to prevent the red-emitting quantum dots from absorbing the fluorescence of the green-emitting quantum dots, it is preferable to place the layer containing the red-emitting quantum dots on the excitation light side and to have the green-emitting quantum dots contained in the layer away from the excitation light.

[0036] In other words, when quantum dots are used as wavelength conversion materials, two or more types of quantum dots with different fluorescent wavelengths are used. For example, in wavelength conversion materials for displays, blue LED light is used as the excitation light for the backlight, and the excitation light is converted by two types of quantum dots: one that emits green light and one that emits red light.

[0037] In this case, the red-emitting quantum dots can absorb not only the excitation light but also the fluorescence from the green-emitting quantum dots, resulting in a decrease in the intensity of the green fluorescence.

[0038] To compensate for this decrease in green emission intensity, i.e., to maintain high green light conversion efficiency, it is necessary to use quantum dots at a higher concentration. However, this increases the tendency for particles to aggregate and causes self-absorption of the green light alone, resulting in a problem that the light conversion efficiency of quantum dots decreases as the concentration increases.

[0039] In addition, a common method is to use a light-scattering agent to keep the quantum dot concentration low, but because all light is scattered, as the scattering effect increases, green light is absorbed by the red-emitting quantum dots and converted to red, which has the negative effect of affecting chromaticity. For this reason, even if the light conversion efficiency can be increased by using a scattering agent, it is not sufficient.

[0040] In contrast, in this embodiment, the upper layer 3a contains red-emitting quantum dots, and the middle layer 3b contains green-emitting quantum dots. This allows the quantum dot concentration in each layer to be kept low. In this case, by arranging the layer containing red-emitting quantum dots on the excitation light side and containing green-emitting quantum dots in the layer away from the excitation light, it is possible to prevent the red-emitting quantum dots from absorbing the fluorescence of the green-emitting quantum dots, thereby improving the light conversion efficiency.

[0041] The lower layer 3c shown in Fig. 4 may contain a functional additive, similar to the upper layer 2a and lower layer 2c in Fig. 3. Furthermore, the quantum dot-containing resin film 3 in Fig. 4 may be formed of two layers, the upper layer 3a and the middle layer 3b, and may not include the lower layer 3c.

[0042] 4, the upper layer 3a and the lower layer 3c may contain quantum dots, and the middle layer 3b may be a resin layer that does not contain quantum dots. In this case, the middle layer 3b may contain a fluorescent material other than quantum dots, such as a fluorescent pigment or fluorescent dye.

[0043] It is preferable to appropriately select the light transmittance and refractive index of the layer not containing quantum dots, taking into consideration the reflection and refraction of light at the interface between the layers.

[0044] The quantum dot-containing resin film 4 of the fourth embodiment shown in Figure 5 has a laminated film structure including an upper layer 4a as a resin layer containing first quantum dots, a lower layer 4c as a resin layer containing second quantum dots, and a middle layer 4b located between the upper layer 4a and the lower layer 4c and containing both the first quantum dots and the second quantum dots. For example, the first quantum dots are green-emitting quantum dots, and the second quantum dots are red-emitting quantum dots. Therefore, the middle layer 4b contains both green-emitting quantum dots and red-emitting quantum dots.

[0045] The green-emitting quantum dots are not contained in the lower layer 4c, but are contained in both the middle layer 4b and the upper layer 4a, with more of them in the upper layer 4a than in the middle layer 4b. Therefore, the green-emitting quantum dots have a concentration gradient in which the concentration increases from the lower layer 4c to the upper layer 4a.

[0046] On the other hand, red-emitting quantum dots are not contained in the upper layer 4a, but are contained in both the middle layer 4b and the lower layer 4c. The lower layer 4c contains more of them than the middle layer 4b. Therefore, the red-emitting quantum dots have a concentration gradient in which the concentration increases from the upper layer 4a to the lower layer 4c.

[0047] Although two different types of quantum dots are used in FIG. 5, for example, one type of quantum dot may be contained in each resin layer at different concentrations, and a concentration gradient may be created for only one type of quantum dot.

[0048] 1 and 3 to 5 have a three-layer film structure, but the number of layers is not limited thereto, and the resin layers used in each layer may be of two or more types.

[0049] Furthermore, the resin molded body is a laminate of two, three or more layers, and it is important that the quantum dots are dispersed in each resin layer. By applying this structure, it is possible to achieve functions such as suppressing self-absorption of quantum dots, suppressing fluorescence absorption by quantum dots with different emission wavelengths, protecting against oxygen and moisture, increasing light conversion efficiency, and light scattering. The required functions can be adjusted by the thickness and combination of each layer. Since the required functions differ depending on the application, the layer structure of the multilayer film is not strictly limited in this embodiment.

[0050] In this embodiment, the concentration of the quantum dots in the entire resin layer is preferably 0.05% or more and 1.5% or less. In this way, in this embodiment, it is possible to reduce the content of the quantum dots, so it is possible to fundamentally avoid the problem of aggregation of the quantum dots.

[0051] In this embodiment, the total thickness of the resin layers is preferably 50 μm or more and 500 μm or less. In this embodiment, the resin layers can be integrated and no adhesive layer is required, allowing for a thinner device.

[0052] In this embodiment, the ratio of the green light intensity to the blue light intensity and the ratio of the red light intensity to the blue light intensity can be set to 0.3 or more. In particular, by forming a resin layer containing red-emitting quantum dots on the excitation light side and containing green-emitting quantum dots in a resin layer away from the excitation light side, it is possible to prevent the red-emitting quantum dots from absorbing the fluorescence of the green-emitting quantum dots, and to obtain the above intensity ratios appropriately.

[0053] In this embodiment, the fluorescence half-width of each of the blue light intensity, green light intensity, and red light intensity can be set to 100 nm or less.

[0054] Next, a method for manufacturing the quantum dot-containing resin film and wavelength conversion member of this embodiment will be described. As shown in Fig. 6, first, a quantum dot solution and resin pellets are mixed and dried (steps ST1 and ST2). This results in resin pellets coated with quantum dots.

[0055] Subsequently, the resin pellets are kneaded, for example, by a twin-screw extruder, and the resulting strands are cut by a pelletizer to obtain resin pellets in which the quantum dots are dispersed in the resin (steps ST3 and ST4).

[0056] Next, multiple types of resin pellets are fed into separate raw material inlets of a molding machine, and are melted by a co-extrusion molding machine while being extruded through a T-die to obtain a quantum dot-containing resin film having a laminated structure (step ST5).

[0057] Then, the quantum dot-containing resin film can be molded to obtain a desired wavelength conversion member (step ST6).

[0058] In this embodiment, two or more separated resin layers can be molded by common resin molding such as co-extrusion, so that wide film can be molded by changing the size of the T-die. In addition, the arrangement of the resin layers can be freely changed, allowing for a high degree of freedom in the design of functional multilayer films.

[0059] Furthermore, in this embodiment, unlike laminated films, no optical adhesive is used, so that a decrease in light transmittance due to an adhesive layer is suppressed, and an unnecessary increase in thickness is also suppressed.

[0060] Furthermore, in the quantum dot-containing film formed by the manufacturing method of this embodiment, it is possible to suppress the decrease in conversion efficiency caused by self-absorption of the quantum dots and increase the luminous efficiency.

[0061] In this embodiment, two or more types of quantum dots are independently dispersed in two or more types of resin layers, and the order of lamination of the resin layers can be freely designed. For example, when used as a wavelength conversion member, it is preferable to place a layer containing red-emitting quantum dots on the excitation light side and place a layer containing green-emitting quantum dots on top of that in order to prevent the red-emitting quantum dots from absorbing the fluorescence of the green-emitting quantum dots.

[0062] In this embodiment, in addition to the resin layer containing quantum dots, a layer having a light diffusing function, an outer layer for film protection, etc. can be appropriately arranged. The resin layer not containing quantum dots can contain a fluorescent material other than quantum dots, such as a fluorescent pigment or fluorescent dye.

[0063] Furthermore, the resins that can be used in this embodiment are basically transparent resins with different refractive indices, but the same material may be used for each layer. Since there are many combinations of these resin types, there is an advantage in that many options are available when designing a product according to the purpose.

[0064] In this embodiment, quantum dots are mechanically mixed into the resin by kneading with an extruder, eliminating the need for pre-dispersion treatment. Therefore, the composition, shape, and shell structure of the quantum dots used are not particularly limited, and cadmium (Cd)-based quantum dots containing Cd or Cd-free quantum dots not containing Cd can be used.

[0065] The resin layer used in this embodiment is an amorphous transparent resin, and light is reflected at the interface between the resin layers due to the difference in refractive index between the two types of resin. By adjusting the difference in refractive index between the two types of resin at the interface of the resin layers, leakage of light whose wavelength has been converted by the quantum dots can be suppressed and it can be extracted efficiently.

[0066] In this embodiment, it is possible to add necessary functions other than the multilayer structure of the resin layer containing quantum dots, and various additives can be used, as explained in Fig. 3. Typical additives include, but are not limited to, light scattering agents, stabilizers, antioxidants, lubricants, antiblocking agents, and plasticizers.

[0067] In this embodiment, an organic or inorganic light scattering agent can be used. In this case, the light scattering agent can be directly mixed in the form of powder and resin pellets during extrusion molding, but it is also possible to form a light diffusion layer by using, as a raw material, a resin into which the light scattering agent has been kneaded in advance so that the light scattering agent is dispersed in a specific phase.

[0068] Furthermore, when placing an outermost layer other than the resin layer in which quantum dots are dispersed, for example to protect against oxygen or water, it is desirable to use a resin such as polyethylene terephthalate (PET), polyvinyl alcohol (Poly(vinylalchol): PVA), or polyethylene vinyl alcohol (Poly(ethylenevinylalchol): EVAL), which has a relatively low oxygen and water permeability.

[0069] In this way, in this embodiment, the quantum dot-containing transparent resin can be molded into any size and shape. Because the molding method is co-extrusion molding, which is an application of conventional extrusion molding, continuous production is possible, and compared to manufacturing methods that include a film lamination process, it is possible to inexpensively manufacture multilayer films with optical functions.

[0070] Furthermore, it is desirable for the amorphous resins constituting the multilayer film in which quantum dots are dispersed to have a large difference in refractive index between the resins used. Therefore, a combination of a resin with a low refractive index and a resin with a high refractive index is preferred. Typical examples include a combination of acrylic resin and a cyclic polyolefin polymer, or a combination of acrylic resin and a polyethylene terephthalate resin. This allows for increased light conversion efficiency without the use of scattering agents due to the reflection and refraction of light at the interface of the resin layers.

[0071] In this embodiment, the resin molded body is made of two or more transparent resin layers, but because the layer structure is manufactured in one process by co-extrusion molding, it basically has an integrated structure with no peeling at the edges or cut surfaces. This layer structure can be confirmed using optical equipment such as a microscope. [Example]

[0072] The effects of the present invention will be explained below by way of examples of the present invention, but the embodiments of the present invention are not limited to the following examples.

[0073] [material] In the experiment, the following materials were used to produce the resin molded body. All raw materials were dried in a vacuum drying oven at reduced pressure and at 80°C or higher for at least one day before use. resin: Cyclic olefin polymer (COP): Zeon Corporation, Zeonor (registered trademark) 1060R Acrylic resin (PMMA): Mitsubishi Gas Chemical Company, Inc. Optimus (registered trademark) 7500FS Polyester resin (PET): Mitsubishi Gas Chemical Company, Inc. Altesta (registered trademark) 4203F Additives: Zinc stearate (ZnSt): Aldrich

[0074] In the experiment, the following materials were used as quantum dots (QDs). All quantum dots (QDs) were prepared in hexane (CH 12 The concentration was determined optically by quantifying the absorbance using a UV-Vis Spectrophotometer V-770 manufactured by JASCO Corporation. Cd-based quantum dots (QDs): green-emitting quantum dots (hereafter referred to as G-QDs) and red-emitting quantum dots (hereafter referred to as R-QDs) with a core / shell structure Cd-free quantum dots (QDs): green-emitting quantum dots (G-QDs) with core / shell structure and red-emitting Cd-free quantum dots (R-QDs)

[0075] [Extruder] Pellet manufacturing extruder Manufacturer: Technovel Co., Ltd. Specifications: Screw diameter: 25mm twin screw extruder L / D:40 Maximum mixing temperature: 400℃ Co-extrusion film extruder Manufacturer: Technovel Co., Ltd. Specifications Screw diameter: 15mm twin screw extruder, 2 15mm single screw extruders, total of 3 extruders L / D:40 Maximum injection temperature: 400℃ T-die width 200mm

[0076] [Optical measurement equipment] spectroradiometer Manufacturer: Topcon Technohouse Corporation SR3-AR and SR3A

[0077] [Optical measurement equipment] Microscope Manufacturer: Keyence Corporation VHX-5000

[0078] [Example 1] Two kg of acrylic resin was mixed with 30 mL of a hexane dispersion of Cd-based G-QDs (the concentration was determined from the optical absorption coefficient, and the required amount of solution was calculated from this value), and the dispersion was applied to the entire pellet. The hexane solution was evaporated to obtain a resin pellet coated with QDs.

[0079] ZnSt (6.0 g: 0.3 wt %) was added to the powder, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0080] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 200 to 230°C, and the resulting strands were cut with a pelletizer to obtain acrylic resin pellets in which QDs were dispersed in the resin.

[0081] The obtained G-QD-containing acrylic resin pellets were dried in a vacuum drying oven at 60°C for 24 hours or more and used in the next step as a Cd-based G-QD-containing acrylic resin masterbatch.

[0082] [Example 2] Two kg of acrylic resin was mixed with 25 mL of a hexane dispersion of Cd-based R-QDs, and the dispersion was applied to the pellets. The hexane solution was then evaporated to obtain acrylic resin pellets coated with QDs.

[0083] ZnSt (4.0 g: 0.2 wt %) was added to this, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0084] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 200 to 230°C, and the resulting strands were cut with a pelletizer to obtain acrylic resin pellets in which QDs were dispersed in the acrylic resin.

[0085] The obtained R-QD-containing acrylic resin pellets were dried in a vacuum drying oven at 60°C for 24 hours or more and used in the next step as a Cd-based R-QD-containing acrylic resin masterbatch.

[0086] [Example 3] 2 kg of COP was mixed with 30 mL of a hexane dispersion of Cd-based G-QDs, and the hexane solution was quickly evaporated to obtain COP resin pellets with QDs coated on the pellet surface.

[0087] ZnSt (6.0 g: 0.3 wt %) was added to the powder, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0088] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 200 to 220°C, and the resulting strands were cut with a pelletizer to obtain pellets in which QDs were dispersed in the COP resin.

[0089] The obtained G-QD-containing COP resin pellets were dried in a vacuum drying oven at 60 °C for 24 hours or more and used in the next step as a Cd-based G-QD-containing COP resin masterbatch.

[0090] [Example 4] 2 kg of COP was mixed with 25 mL of a hexane dispersion of Cd-based R-QDs, and the hexane solution was quickly evaporated to obtain COP resin pellets with QDs coated on the pellet surface.

[0091] ZnSt (4.0 g: 0.2 wt %) was added to this, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0092] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 200 to 220°C, and the resulting strands were cut with a pelletizer to obtain pellets in which QDs were dispersed in the COP resin.

[0093] The obtained R-QD-containing COP resin pellets were dried in a vacuum drying oven at 60°C for 24 hours or more and used in the next step as a Cd-based R-QD-containing COP resin masterbatch.

[0094] [Example 5] 2 kg of PET resin was mixed with 30 mL of a hexane dispersion of Cd-based G-QDs to obtain PET resin pellets coated with QDs.

[0095] ZnSt (6.0 g: 0.3 wt %) was added to the powder, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0096] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 220 to 230°C, and the resulting strands were cut with a pelletizer to obtain pellets in which QDs were dispersed in the PET resin.

[0097] The obtained G-QD-containing PET resin pellets were dried in a vacuum drying oven at 60 °C for more than 24 hours and used in the next step as a Cd-based G-QD-containing PET resin masterbatch.

[0098] [Example 6] 2 kg of PET resin was mixed with 25 mL of a hexane dispersion of Cd-based G-QDs to obtain PET resin pellets coated with QDs.

[0099] ZnSt (4.0 g: 0.2 wt %) was added to this, and the pellets and powder were dry mixed to coat the ZnSt on the surfaces of the PET pellets.

[0100] This was fed into the raw material inlet of a twin-screw extruder and kneaded at a temperature of 220 to 230° C. The resulting strand was cut with a pelletizer to obtain pellets in which QDs were dispersed in the PET resin.

[0101] The obtained R-QD-containing PET resin pellets were dried in a vacuum drying oven and used in the next step as a Cd-based R-QD-containing PET resin masterbatch.

[0102] [Example 7] Two kg of acrylic resin was mixed with 40 mL of a hexane dispersion of Cd-free G-QDs, and the dispersion was applied to the pellets. The hexane solution was then evaporated to obtain resin pellets coated with QDs.

[0103] ZnSt (10.0 g: 0.5 wt %) was added to the powder, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0104] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 200 to 230°C, and the resulting strands were cut with a pelletizer to obtain acrylic resin pellets in which QDs were dispersed in the resin.

[0105] The obtained G-QD-containing acrylic resin pellets were dried in a vacuum drying oven at 60°C for 24 hours or more and used in the next step as a Cd-free G-QD-containing acrylic resin masterbatch.

[0106] [Example 8] Two kg of acrylic resin was mixed with 60 mL of a hexane dispersion of Cd-free R-QDs, and the dispersion was applied to the pellets. The hexane solution was then evaporated to obtain resin pellets coated with QDs.

[0107] ZnSt (6.0 g: 0.3 wt %) was added to the powder, and the pellets and powder were dry mixed to coat the pellet surfaces with ZnSt.

[0108] The pellets thus obtained were kneaded in a twin-screw extruder at a molding temperature of 200 to 230°C, and the resulting strands were cut with a pelletizer to obtain pellets in which QDs were dispersed in the acrylic resin.

[0109] The obtained R-QD-containing acrylic resin pellets were dried in a vacuum drying oven at 60°C for 24 hours or more and used in the next step as a Cd-free R-QD-containing acrylic resin masterbatch.

[0110] Examples 1 to 8 are summarized in Table 1. The QD concentrations shown in Table 1 are calculated values ​​obtained from the correlation between optically determined concentrations and QD weights (wt%) obtained by thermogravimetric analysis (TGA).

[0111] [Table 1]

[0112] [Example 9] 1 kg of PET resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1), 400 g of the Cd-based G-QD-containing acrylic resin masterbatch prepared in Example 1 mixed with 600 g of acrylic resin raw material was charged into raw material inlet 2 of the molding machine (resin layer 2), and 1 kg of PET resin pellet raw material was charged into raw material inlet 3 (resin layer 3).

[0113] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0114] By adjusting the extrusion speed and winding speed, a film with a total thickness of 320 μm was formed. The obtained film was wound on a roll, cut to the required size, and its spectrum was measured using a spectroradiometer.

[0115] [Example 10] 1 kg of PET resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1), 800 g of the Cd-based R-QD-containing acrylic resin masterbatch prepared in Example 2 mixed with 200 g of acrylic resin raw material was charged into raw material inlet 2 of the molding machine (resin layer 2), and the PET resin pellet raw material was charged into raw material inlet 3 (resin layer 3).

[0116] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0117] By adjusting the extrusion speed and winding speed, a film with a total thickness of 350 μm was formed.

[0118] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0119] [Example 11] 500 g of PET resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1), and a mixture of 250 g of the Cd-based G-QD-containing acrylic resin masterbatch prepared in Example 1, 500 g of the Cd-based R-QD-containing acrylic resin masterbatch prepared in Example 2, and 250 g of the acrylic resin pellet raw material was charged into raw material inlet 2 of the molding machine (resin layer 2), and the acrylic resin pellet raw material was charged into raw material inlet 3 (resin layer 3).

[0120] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0121] By adjusting the extrusion speed and winding speed, a film with a total thickness of 360 μm was formed.

[0122] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0123] [Example 12] 500 g of the Cd-based R-QD-containing acrylic resin masterbatch prepared in Example 2 was charged into raw material inlet 1 of the molding machine (resin layer 1), 250 g of the Cd-based G-QD-containing acrylic resin masterbatch prepared in Example 1 was mixed with 250 g of acrylic resin pellet raw material and charged into raw material inlet 2 of the molding machine (resin layer 2), and 500 g of the acrylic resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0124] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0125] By adjusting the extrusion speed and winding speed, a film with a total thickness of 350 μm was formed.

[0126] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0127] [Example 13] 1 kg of acrylic resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1), and a total of 1 kg of pellet mixture, consisting of 250 g of the Cd-based G-QD-containing acrylic resin masterbatch prepared in Example 1, 500 g of the Cd-based R-QD-containing acrylic resin masterbatch prepared in Example 2, and 250 g of the acrylic resin pellet raw material, was charged into raw material inlet 2 of the molding machine (resin layer 2), and 1 kg of the acrylic resin pellet raw material was charged into raw material inlet 3 (resin layer 3).

[0128] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0129] By adjusting the extrusion speed and winding speed, a film with a total thickness of 380 μm was formed.

[0130] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0131] [Example 14] 500 g of the Cd-based R-QD-containing COP resin pellet raw material masterbatch prepared in Example 4 was charged into raw material inlet 1 of the molding machine (resin layer 1), 250 g of the G-QD-containing COP resin masterbatch prepared in Example 3 mixed with 250 g of the COP resin pellet raw material was charged into raw material inlet 2 of the molding machine (resin layer 2), and 500 g of the COP resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0132] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0133] By adjusting the extrusion speed and winding speed, a film with a total thickness of 320 μm was formed.

[0134] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0135] [Example 15] 500 g of PET resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1), 250 g of the Cd-based R-QD-containing COP resin masterbatch prepared in Example 4 was mixed with 250 g of COP resin pellet raw material and charged into raw material inlet 2 of the molding machine (resin layer 2), and 500 g of PET resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0136] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0137] By adjusting the extrusion speed and winding speed, a film with a total thickness of 360 μm was formed.

[0138] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0139] [Example 16] A mixture of 250 g of the Cd-based R-QD-containing PET resin masterbatch prepared in Example 6 and 250 g of PET resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1). A mixture of 250 g of the Cd-based G-QD-containing acrylic resin masterbatch prepared in Example 1 and 250 g of acrylic resin pellet raw material was charged into raw material inlet 2 of the molding machine (resin layer 2). 500 g of the PET resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0140] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0141] By adjusting the extrusion speed and winding speed, a film with a total thickness of 200 μm was formed.

[0142] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0143] [Example 17] A mixture of 250 g of the Cd-based R-QD-containing COP resin masterbatch prepared in Example 4 and 250 g of the COP resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1). A mixture of 250 g of the Cd-based G-QD-containing COP resin masterbatch prepared in Example 3 and 250 g of the Cd-based R-QD-containing COP resin masterbatch prepared in Example 4 was charged into raw material inlet 2 of the molding machine (resin layer 2). A mixture of 250 g of the Cd-based G-QD-containing COP resin masterbatch prepared in Example 3 and 250 g of the COP resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0144] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0145] By adjusting the extrusion speed and winding speed, a film with a thickness of 140 μm was formed.

[0146] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0147] [Example 18] 500 g of the Cd-free R-QD-containing acrylic resin masterbatch prepared in Example 8 was charged into raw material inlet 1 of the molding machine (resin layer 1), 250 g of the Cd-free G-QD-containing acrylic resin masterbatch prepared in Example 7 mixed with 250 g of acrylic resin pellet raw material was charged into raw material inlet 2 of the molding machine (resin layer 2), and 500 g of PET resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0148] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0149] By adjusting the extrusion speed and winding speed, a film with a total thickness of 240 μm was formed.

[0150] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0151] [Example 19] A mixture of 250 g of the Cd-free R-QD-containing acrylic resin masterbatch prepared in Example 8 and 250 g of acrylic resin pellet raw material was charged into raw material inlet 1 of the molding machine (resin layer 1). A mixture of 250 g of the Cd-based G-QD-containing acrylic resin masterbatch prepared in Example 1 and 250 g of acrylic resin pellet raw material was charged into raw material inlet 2 of the molding machine (resin layer 2). 500 g of the acrylic resin pellet raw material was charged into raw material inlet 3 of the molding machine (resin layer 3).

[0152] This was melted at a molding temperature of 200 to 240°C using a co-extrusion molding machine and extruded through a T-die to obtain a film having a three-layer structure.

[0153] By adjusting the extrusion speed and winding speed, a film with a total thickness of 220 μm was formed.

[0154] The obtained film was wound on a roll, cut into pieces of the required size, and subjected to spectrum measurement using a spectroradiometer.

[0155] Examples 9 to 19 are summarized in Table 2. The QD concentrations shown in Table 2 are calculated values ​​obtained from the correlation between optically determined concentrations and QD weights (wt%) obtained by thermogravimetric analysis (TGA). The total thicknesses shown in Table 2 are actual values ​​measured using a micrometer.

[0156] [Table 2]

[0157] The results of the enlarged observations of the film cross section shown in Figures 7 to 13 demonstrated that the film actually consists of three layers, with the desired quantum dots (QDs) uniformly dispersed.

[0158] Furthermore, all of the three-layer films in Examples 9 to 19 had an integral structure, except for Example 15, and even when they were finely crushed, no peeling of the surface layer occurred from the fragmented film. Only Example 15 experienced interlayer peeling when force was applied, which is thought to be due to the low compatibility between the PET resin and the COP resin.

[0159] Figures 14 to 26 show the RGB spectra of the quantum dot-containing resin film when the backlight is turned on. Measurements were performed using a Topcon Technohouse SR3-A. Measurements were also performed using a 3M Brightness Enhancement Film (BEF).

[0160] Figures 14, 15, and 22 show the spectra of films containing monochromatic Cd-based G-QDs (Example 9), Cd-based R-QDs (Example 10), and Cd-based R-QDs (Example 15) in the middle layer, respectively. The peaks of the excitation light (450 nm) converted to green and red by the QDs were observed. This confirmed that QDs were indeed present and that wavelength conversion of the excitation light was occurring.

[0161] Figures 16, 17, 19, and 20 show the spectra of the films of Examples 11, 12, 13, and 14, respectively. All of the films contain both G-QDs and R-QDs in the same or separate layers within the film. The peaks in each figure confirm that the excitation light is converted to both green and red by a single film.

[0162] In Examples 11 and 13, both G-QDs and R-QDs were dispersed in the middle layer, and the concentrations of each QD were adjusted to achieve equivalent excitation light absorbance. Ideally, the G-QDs and R-QDs were designed to have equivalent peak intensities. However, in Figures 16 and 19, the intensity of the red fluorescence peak is overwhelmingly higher than that of the green. This is due to the R-QDs absorbing the G-QD fluorescence, resulting in a significant decrease in the green fluorescence intensity and an increase in the red fluorescence intensity. The overall brightness of the film was significantly reduced, which is the problem of reduced light conversion efficiency using QD films mentioned earlier.

[0163] On the other hand, in Examples 12 and 14, the G-QDs and R-QDs were present in separate layers. In Figures 17 and 20, the green and red fluorescence peaks were close in intensity. This demonstrates that the above problem can be significantly improved by placing the G-QDs and R-QDs in separate layers.

[0164] Figures 18 and 21 show the spectra of the films of Examples 12 and 14, respectively, measured with a backlight on the reverse side. That is, Figures 17 and 18 show the spectra of the film of Example 12, and Figure 18 shows the spectra of the film of Example 12 shown in Figure 17, measured with the film turned over. Also, Figures 20 and 21 show the spectra of the film of Example 14, and Figure 21 shows the spectra of the film of Example 14 shown in Figure 20, measured with the film turned over.

[0165] The intensity ratio of green to red fluorescence was different when the film of Example 12 was turned over and measured. That is, the spectrum did not change and the RGB ratio was the same whether the R-QD-containing layer was above the G-QD layer (Figure 17) or the G-QD layer was above the R-QD layer (Figure 18).

[0166] Similarly, for the film of Example 14, although the layer structure of the film was asymmetric, no difference in optical properties was observed between the front and back sides (FIGS. 20 and 21).

[0167] The reason for this is thought to be that measurements were made using a brightness enhancement film (BEF). When measuring with a BEF, light is reflected repeatedly within the film, meaning that light is absorbed, scattered, and wavelength-converted not only from bottom to top but also from top to bottom as it passes through, and this is thought to be why the asymmetry of the film structure was not reflected in the optical properties.

[0168] To confirm that the asymmetry of the film structure affects the optical properties, the same measurements were performed on the film prepared in Example 12 without using BEF. The spectra in Figures 27 and 28 show that the G / R ratios are indeed different, proving that the optical properties of the film differ between the front and back surfaces.

[0169] The difference between the front and back of the film prepared in Example 14 was also confirmed (Figures 29 and 30). This is thought to be due to the fact that the QDs placed on the excitation light side convert light first, and that the R-QDs absorb not only the excitation light but also the green fluorescence and convert it to red.

[0170] Figure 23 shows the spectrum of Example 16. The R-QD concentration is designed to increase from the bottom layer to the top layer.

[0171] Figure 25 shows the spectrum of the three-layer film containing Cd-free G-QDs and Cd-free R-QDs prepared in Example 18. The spectrum clearly demonstrated that the film contained green and red fluorescence.

[0172] Figure 26 shows the spectrum of a three-layer hybrid QD film prepared in Example 19, which contains Cd-based G-QDs in the middle layer and Cd-free R-QDs in the outer layer. The spectrum clearly demonstrates that the film contains green and red fluorescence converted by the Cd-based G-QDs. [Industrial Applicability]

[0173] According to the present invention, a wavelength conversion member for a backlight having excellent light conversion efficiency can be suitably used as a wavelength conversion member.

[0174] 1, 2, 3, 4: Quantum dot-containing resin film 1a, 2a, 3a, 4a: Upper layer 1b, 2b, 3b, 4b: Middle layer 1c, 2c, 3c, 4c: Lower layer 10: Quantum dots 10a: Core 10b: Shell 11:Organic ligand

Claims

1. A plurality of resin layers are laminated, and at least one of the resin layers contains quantum dots; The plurality of resin layers are integrated by co-extrusion molding, the resin layer has a three-layer structure including a middle layer containing the quantum dots, and upper and lower layers that do not contain the quantum dots and are formed above and below the middle layer, the upper layer and the lower layer contain a light scattering agent, There is no adhesive layer at the interface between the middle layer and the upper layer and at the interface between the middle layer and the lower layer, and the resin layers are directly bonded to each other; The concentration of the quantum dots in the entire resin layer is 0.05% or more and 1.5% or less, the intermediate layer contains the quantum dots having a core / shell structure, PMMA or COP, and zinc stearate; A wavelength conversion member for a backlight, characterized in that:

2. A wavelength conversion member for a backlight as described in Claim 1, characterized in that the resin layers used in the upper layer and the lower layer are selected from PMMA, COP, or PET.

3. 3. The wavelength conversion member for a backlight according to claim 1, wherein the resin layer containing the quantum dots and the resin layer not containing the quantum dots are integrated together.

4. 4. The wavelength conversion member for a backlight according to claim 3, wherein the resin layer not containing the quantum dots contains a functional additive.

5. 2. The wavelength conversion member for a backlight according to claim 1, wherein the quantum dots include at least green-emitting quantum dots and red-emitting quantum dots.

6. 2. The wavelength conversion member for a backlight according to claim 1, wherein the resin layer is made of an amorphous resin.

7. 7. The wavelength conversion member for a backlight according to claim 1, wherein the resin layer has a total thickness of 50 μm or more and 500 μm or less.

8. 8. The wavelength conversion member for backlight according to claim 1, wherein the ratio of green light intensity to blue light intensity and the ratio of red light intensity to blue light intensity are each 0.3 or more.

9. 9. The wavelength conversion member for backlight according to claim 1, wherein each of the fluorescence half-widths of blue light intensity, green light intensity, and red light intensity is 100 nm or less.

10. A wavelength conversion member obtained by molding using the wavelength conversion member for backlights according to any one of claims 1 to 9.

11. A method for producing a wavelength conversion member for a backlight according to any one of claims 1 to 10, comprising: forming resin pellets containing quantum dots; A method for manufacturing a wavelength conversion member for a backlight, comprising: a step of integrating three resin layers by co-extrusion molding.

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