Quantum dot light conversion film and its preparation method, backlight module

Abstract

This disclosure provides a quantum dot light conversion film, its preparation method, and a backlight module containing the same. The quantum dot light conversion film includes a base film, a first quantum dot film layer, a second quantum dot film layer, and an encapsulation film layer sequentially contacted together. The base film includes a barrier film layer and a PET film layer, and the barrier properties of the base film are WVTR ≤ 2 g / m². 2 The first quantum dot film layer comprises a first quantum dot and a first resin, the second quantum dot film layer comprises a second quantum dot and polyethylene terephthalate, and the encapsulation film layer comprises a second resin and inorganic oxide particles. The first and second quantum dots are selected from one or both of red and green quantum dots. The combined mass fraction of red and green quantum dots in the first quantum dot film layer is 0.01-1%. The dual quantum dot film layer structure can reduce the quantum dot content of the first quantum dot film layer, reduce the color dot fluctuation of this layer, and make it easier to produce products with stable color dot batches.

Description

Technical Field

[0001] This disclosure relates to the field of quantum dot light conversion technology, and more specifically, to a quantum dot light conversion film and its preparation method, and a backlight module. Background Technology

[0002] A typical quantum dot light conversion film has a sandwich structure, consisting of upper and lower barrier films and a middle layer of red and green quantum dot resin. Due to the protection of the barrier films, the quantum dots in the quantum dot layer are generally selected for their high performance efficiency and narrow half-width at half-maximum (WHM), such as <20nm, resulting in better color gamut coverage. However, this also leads to higher costs, hindering its large-scale application. Furthermore, because the red and green quantum dot resin layers have a high quantum dot content, controlling the related color points (chromatic coordinates) is difficult. Considering the thickness fluctuations in coating equipment, if the red and green quantum dot resin layers are too thin, the color point deviation caused by coating thickness fluctuations (e.g., ±3μm) will lead to color point deviations in the display device, causing quality problems. Therefore, the resin layer thickness is generally around 100μm. Further reducing the thickness will easily cause color point deviations, meaning that the color points of the same batch or different batches of quantum dot light conversion films will be different, leading to product quality issues. Therefore, it is difficult to achieve ultra-thin quantum dot light conversion films. Summary of the Invention

[0003] The purpose of this disclosure is to provide a quantum dot light conversion film and its preparation method, as well as a backlight module. The structural design of the quantum dot light conversion film solves the problem of large fluctuations in film thickness and color point in the production of quantum dot light conversion films.

[0004] According to a first aspect of this disclosure, a quantum dot light conversion film is provided, comprising a base film, a first quantum dot film layer, a second quantum dot film layer, and an encapsulation film layer sequentially contacted and disposed therein; the base film includes a barrier film layer and a PET film layer, and the barrier properties of the base film are WVTR ≤ 2 g / m 2 The first quantum dot film layer comprises a first quantum dot and a first resin, the second quantum dot film layer comprises a second quantum dot and polyethylene terephthalate, and the encapsulation film layer comprises a second resin and inorganic oxide particles. The first quantum dot and the second quantum dot are selected from one or both of red quantum dots and green quantum dots. The total mass fraction of red quantum dots and green quantum dots in the first quantum dot film layer is 0.01-1%.

[0005] Optionally, the refractive index of the first resin is lower than that of the PET film layer, the refractive index of the first resin is between 1.38 and 1.6, and the refractive index of the encapsulation film layer is higher than that of the first resin.

[0006] Optionally, the combined mass fraction of red and green quantum dots in the second quantum dot film is 0.01-20%, preferably 0.1-10%. Preferably, the first and second quantum dot films also contain second diffused particles.

[0007] Optionally, the thickness of the first quantum dot film is 1–100 μm, preferably 3–70 μm; the thickness of the second quantum dot film is 6–250 μm, preferably 12–125 μm.

[0008] Optionally, the thickness of the base film is 12–125 μm, and the thickness of the encapsulation film is 0.5–25 μm.

[0009] Optionally, the thickness of the quantum dot light conversion film is 37.5–75 μm.

[0010] Optionally, the second resin material includes one or more of acrylic resin, epoxy resin, and silicone resin, and the inorganic oxide particles are selected from one or more of zirconium oxide, titanium oxide, and silicon oxide.

[0011] Optionally, the fluorescence half-width at half-maximum (FWHM) of the first quantum dot film is less than or equal to 25 nm and the external quantum efficiency is greater than or equal to 40%, and / or the fluorescence half-width at half-maximum (FWHM) of the second quantum dot film is greater than or equal to 25 nm and the external quantum efficiency is less than 40%.

[0012] According to a second aspect of this disclosure, a method for preparing the aforementioned quantum dot light conversion film is provided, comprising: melt co-extruding a composition containing the second quantum dots and polyethylene terephthalate particles to obtain a single layer or multiple layers of the second quantum dot film; preparing the base film and an adhesive containing the first quantum dots; applying the adhesive containing the first quantum dots between the base film and the second quantum dot film using a coating device, and curing it to obtain an intermediate, the intermediate comprising the base film, the first quantum dot film, and the second quantum dot film sequentially contacted; coating the second quantum dot film with an adhesive containing the inorganic oxide particles, and curing it to obtain the encapsulation film layer, ultimately obtaining the quantum dot light conversion film.

[0013] Optionally, the composition containing the second quantum dot includes a red quantum dot masterbatch, a green quantum dot masterbatch, a diffusion masterbatch, a stabilizer, and an antioxidant.

[0014] According to a third aspect of this disclosure, a backlight module is provided, comprising any of the aforementioned quantum dot light conversion films.

[0015] By applying the above solution, the quantum dot content of the first quantum dot film layer can be reduced, the color dot fluctuation of this layer can be reduced, and it is easier to produce products with stable color dot batches. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:

[0017] Figure 1 A schematic diagram of one embodiment of this application is shown.

[0018] Figure 2 A flowchart of one embodiment of this application is shown.

[0019] Figure 3 The aging performance diagrams of embodiments and comparative examples of this application are shown.

[0020] 1. Base film; 2. First quantum dot film layer; 3. Second quantum dot film layer; 4. Encapsulation film layer.

[0021] For ease of understanding, the positions, dimensions, and extents of the structures shown in the accompanying drawings and other materials may not represent actual positions, dimensions, and extents. Therefore, this disclosure is not limited to the positions, dimensions, and extents disclosed in the accompanying drawings and other materials. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] In addition, techniques, methods and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods and equipment should be considered part of the specification.

[0024] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0025] The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “upper,” “lower,” “high,” “lower,” etc., used in the specification and claims, if present, are for descriptive purposes and not necessarily for describing unchanging relative positions. It should be understood that such terms are interchangeable where appropriate, enabling the embodiments of this disclosure described herein to operate, for example, in orientations different from those shown or otherwise described herein. For example, when the device in the drawings is reversed, a feature previously described as “above” other features may now be described as “below” other features. The device may also be oriented in other ways (rotated 90 degrees or in other orientations), in which case the relative spatial relationships will be interpreted accordingly.

[0026] In the specification and claims, when an element is described as being "on top of," "attached" to, "connected" to, "coupled" to, or "coupled" to another element, the element may be directly located on top of, directly attached to, directly connected to, directly coupled to, or directly coupled to the other element, or one or more intermediate elements may be present. Conversely, when an element is described as being "directly" located on top of, directly attached to, directly connected to, directly coupled to, or directly coupled to another element, no intermediate elements are present. In the specification and claims, when a feature is arranged "adjacent" to another feature, it may mean that a feature has a portion overlapping with the adjacent feature or a portion located above or below the adjacent feature.

[0027] As used herein, the term "exemplary" means "serving as an example, embodiment, or illustration," and not as a "model" to be precisely copied. Any implementation described herein by example is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, this disclosure is not limited to any theory expressed or implied as given in the field of art, background art, summary of invention, or detailed description.

[0028] As used herein, the term "substantially" means any minor variation resulting from design or manufacturing defects, device or component tolerances, environmental influences, and / or other factors. The term "substantially" also allows for differences from the perfect or ideal situation due to parasitic effects, noise, and other practical considerations that may exist in the actual implementation.

[0029] Additionally, terms such as “first,” “second,” etc., may be used in this document for reference purposes only and are not intended to be limiting. For example, unless the context clearly indicates otherwise, the words “first,” “second,” and other such numerical terms relating to structures or elements do not imply order or sequence.

[0030] It should also be understood that when the term “including / contains” is used herein, it indicates the presence of the indicated feature, whole, step, operation, unit and / or component, but does not preclude the presence or addition of one or more other features, wholes, steps, operations, units and / or components and / or combinations thereof.

[0031] In this disclosure, the term “provide” is used broadly to cover all ways of obtaining an object, and therefore “provide an object” includes, but is not limited to, “purchasing,” “preparing / manufacturing,” “arranging / setting up,” “installing / assembling,” and / or “ordering” an object.

[0032] As used herein, the term “and / or” includes any and all combinations of one or more of the listed items in association. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise.

[0033] According to a first aspect of this application, a quantum dot light conversion film is provided, comprising a base film, a first quantum dot film layer, a second quantum dot film layer, and an encapsulation film layer sequentially contacted and disposed therein; the base film includes a barrier film layer and a PET film layer, and the barrier properties of the base film are WVTR≤2g / m 2 The first quantum dot film layer comprises first quantum dots and a first resin; the second quantum dot film layer comprises second quantum dots and polyethylene terephthalate; the encapsulation film layer comprises a second resin and an inorganic oxide; the first and second quantum dots comprise one or both of red and green quantum dots; the combined mass fraction of red and green quantum dots in the first quantum dot film layer is 0.01-1%. WVTR refers to Water Vapor Transmission Rate.

[0034] The ratio of red to green quantum dots in the first and second quantum dot films can be flexibly adjusted. The presence of the second quantum dot film reduces the quantum dot content in the first film, lowering color dot variability and making it easier to produce products with stable color dot batches. Furthermore, the inorganic oxide particles in the encapsulation film diffuse light, improving the luminescence uniformity of the quantum dot light conversion film.

[0035] In the base film, the barrier layer is closer to the first quantum dot layer than the PET film layer. In some embodiments, the barrier properties of the base film are WVTR ≤ 0.5 g / m³. 2 • day, preferably ≤0.08g / m 2 • The higher the barrier properties of the base film, the higher the cost, but the better the protection effect on quantum dots.

[0036] In some embodiments, the refractive index of the first resin is lower than that of the PET film layer, and the refractive index of the first resin is between 1.38 and 1.6, preferably between 1.45 and 1.58. The refractive index of the encapsulation film layer is higher than that of the first resin. Combined with the multi-layered, tightly packed structure design, total internal reflection within the film layers is avoided, improving the light extraction rate and increasing the brightness of the quantum dot light conversion film during use.

[0037] In some embodiments, the barrier properties of the encapsulation film are worse than those of the base film, and the cost of the encapsulation film is lower than that of the base film, thus reducing the overall cost of the quantum dot light conversion film.

[0038] In some embodiments, the hardness range of the quantum dot light conversion film is HB-3H.

[0039] In some embodiments, both the first quantum dot and the second quantum dot include two or more quantum dots with different emission peak wavelengths.

[0040] In some embodiments, the combined mass fraction of red and green quantum dots in the second quantum dot film is 0.01-20%, preferably 0.1-10%, 0.1-1.5%, or 0.1-1%. This is calculated based on the color dot requirements and the quantum dot mass fraction of the first quantum dot film.

[0041] In some embodiments, the first quantum dot film further includes first diffused particles. The first diffused particles may be organosilicon particles or inorganic oxide particles. In some embodiments, the mass fraction of the organosilicon particles is 0.3-5%. In some embodiments, the inorganic oxide particles of the first diffused particles are titanium oxide, zirconium oxide, silicon oxide, etc., with a D50 particle size of less than 1 μm and a mass fraction of 0.1-2%.

[0042] In some embodiments, the second quantum dot film further comprises second diffused particles, which are inorganic oxide particles, such as titanium oxide, zirconium oxide, silicon oxide, etc., and the mass fraction of the second diffused particles is 0.5-5%. In some embodiments, the second quantum dot film further comprises an antioxidant, with a mass fraction of 0.1-5%.

[0043] In some embodiments, the particle size of the second diffusing particle D50 is 2-4 times that of the particle size of the first diffusing particle D50.

[0044] In some embodiments, the thickness of the first quantum dot film is 1–100 μm, preferably 3–70 μm; the thickness of the second quantum dot film is 6–250 μm, preferably 12–125 μm.

[0045] In some embodiments, the thickness of the first quantum dot film is 20–50 μm, and the thickness of the second quantum dot film is 23–75 μm.

[0046] In some embodiments, the thickness of the base film is 12–125 μm, and the thickness of the encapsulation film layer is 0.5–25 μm.

[0047] In some embodiments, the thickness of the quantum dot light conversion film is 19.5–500 μm, 37.5–345 μm, 37.5–220 μm, 37.5–150 μm, or 37.5–100 μm.

[0048] In some embodiments, the thickness of the quantum dot light conversion film is 37.5–75 μm or the thickness of the quantum dot light conversion film is 37.5–70 μm. This range is the thickness range of the ultrathin film.

[0049] In some embodiments, the second resin material includes one or more of acrylic resin, epoxy resin, and silicone resin, and the inorganic oxide particles are one or more of zirconium oxide, titanium oxide, and silicon oxide. The second resin is preferably a resin with low water and oxygen permeability. The refractive index of the inorganic oxide particles should be relatively high, so that the refractive index of the encapsulation film is higher than that of the first resin.

[0050] In some embodiments, the material of the first resin is selected from one or more of acrylic resin, epoxy resin, and silicone resin.

[0051] In some embodiments, the inorganic oxide particles account for 0.1-2% of the mass of the encapsulation film. This results in a better light extraction efficiency for the quantum dot light conversion film.

[0052] In some embodiments, the particle size D50 of the inorganic oxide particles in the encapsulation film is less than 5 μm, preferably less than 0.5 μm.

[0053] In some embodiments, the fluorescence half-width at half-maximum (FWHM) of the first quantum dot film is less than or equal to 25 nm, and the external quantum efficiency is greater than or equal to 40%. Preferably, the fluorescence half-width at half-maximum and quantum efficiency of the first quantum dot film are superior to those of the second quantum dot film. This makes it more suitable for the preparation method described below.

[0054] In some embodiments, the fluorescence half-width at half-maximum of the second quantum dot film is greater than or equal to 25 nm, and the external quantum efficiency is less than 40%. According to the following method for preparing the second quantum dot film, the extrusion process reduces its luminescence performance.

[0055] A second aspect of this application provides a method for preparing a quantum dot light conversion film according to any one of the above claims, comprising: melt co-extruding a composition containing second quantum dots and polyethylene terephthalate particles to obtain a single layer or multiple layers of second quantum dot film; preparing a base film and an adhesive containing first quantum dots; applying the adhesive containing first quantum dots between the base film and the second quantum dot film using a coating device, and curing it to obtain an intermediate, the intermediate comprising a base film, a first quantum dot film, and a second quantum dot film sequentially contacted; applying an adhesive containing inorganic oxide particles onto the second quantum dot film, and curing it to obtain an encapsulation film, ultimately obtaining a quantum dot light conversion film.

[0056] The above preparation method reduces the difficulty of color dot control. Firstly, the second quantum dot film layer is used as a standard; adjusting only the color dots of the first quantum dot film layer (by adjusting the corresponding adhesive formulation) is sufficient to adjust the final color dots of the quantum dot light conversion film. Since the second quantum dot film layer already contains some quantum dots, the quantum dot content in the first quantum dot film layer can be reduced, thus significantly reducing the thickness-color dot fluctuation during its preparation. Furthermore, the presence of the second quantum dot film layer also allows for a substantial reduction in the thickness of the first quantum dot film layer. Moreover, since the melt extrusion method for the second quantum dot film layer can achieve ultrathin thicknesses, the quantum dot light conversion film can also be made ultrathin. This preparation method reduces the difficulty of producing ultrathin films and quantum dot light conversion films with high color dot accuracy.

[0057] The second quantum dot film layer is prepared by single-layer or multi-layer extrusion process without changing the conventional PET bi-extrusion equipment and process, reducing the investment in equipment and process. The preparation cost of the second quantum dot film layer is low, and the thickness can be controlled within a relatively thin range, such as as low as 6 micrometers.

[0058] The intermediate can be prepared using a roll-to-roll production process to improve production efficiency. For specific processes, please refer to existing technologies.

[0059] If only the second quantum dot film layer method described above is used to prepare the quantum dot light conversion film, the following problems will be encountered: 1. Waste caused by the color dot control process. Different display device models all require color dot control of the quantum dot light conversion film or color dot monitoring during the production process. Due to the high speed of the biaxial extrusion equipment (generally above 80m / min), the color dot control and confirmation process will cause significant material waste, thereby increasing costs; 2. Poor color rendering performance. In order to meet the requirements of its high-temperature extrusion process, the quantum dot material undergoes many protective treatments, thus sacrificing a lot of performance, such as relatively low quantum efficiency and generally wide half-width; 3. At the same time, because the second quantum dot film layer has a homogeneous structure, the optical path after incident light enters is short, resulting in less light absorption, and thus less red and green light converted, making it difficult to achieve the high color gamut quantum dot solution required by display device customers; 4. Due to the poor hardness of PET as the film layer matrix. This solution can ensure that the hardness of the quantum dot light conversion film is suitable for the assembly of display devices.

[0060] In some embodiments, the preparation of the second quantum dot film and the preparation of the first quantum dot adhesive can be carried out simultaneously or sequentially, and the order can also be reversed.

[0061] In some embodiments, the composition containing the second quantum dots includes a red quantum dot masterbatch, a green quantum dot masterbatch, a stabilizer, a diffusion masterbatch, and an antioxidant. The raw materials for each masterbatch include polymers, such as polyethylene terephthalate (PET). In some embodiments, the quantum dot masterbatch comprises a mixture of quantum dot raw materials and PET, which can be prepared by melt co-extrusion granulation of the raw materials. The aforementioned quantum dot raw materials may also undergo a coating treatment before use to improve the stability of the quantum dots. The preparation of the quantum dot masterbatch also includes the addition of antioxidants, stabilizers, etc., to reduce damage to the quantum dots. In some embodiments, the composition containing the second quantum dots further includes second diffusion particles, which are inorganic oxide particles, such as titanium dioxide, zirconium oxide, silicon dioxide, etc., with a mass fraction of 0.5-5%. In some embodiments, the composition containing the second quantum dots has an antioxidant mass fraction of 0.1-5%.

[0062] In some embodiments, the adhesive containing the first quantum dots comprises quantum dots, a photoinitiator, and a polymer precursor of a first resin. In some embodiments, the adhesive containing the first quantum dots further comprises first diffusing particles. The first diffusing particles are such as organosilicon particles or inorganic oxide particles. In some embodiments, the mass fraction of the organosilicon particles is 0.3-5%. In some embodiments, the inorganic oxide particles of the first diffusing particles are titanium oxide, zirconium oxide, silicon oxide, etc., with a D50 particle size of less than 1 μm and a mass fraction of 0.1-2%.

[0063] In some embodiments, the adhesive containing the first inorganic oxide particles includes the inorganic oxide particles, a photoinitiator, and a polymer precursor of the second resin. The polymer precursor of the second resin may be the same as or different from the polymer precursor of the first resin.

[0064] In some embodiments, the melting temperature is 260-320°C.

[0065] In some embodiments, red quantum dot masterbatch, green quantum dot masterbatch, and PET particles are prepared by bi-wire co-extrusion.

[0066] In some embodiments, the quantum dot masterbatch contains materials that protect the quantum dots at high temperatures, such as antioxidants and stabilizers.

[0067] In some embodiments, the curing method can be light curing or heat curing, depending primarily on the properties of the adhesive. The curing conditions in the different steps described above can be the same or different.

[0068] In some embodiments, the total quantum dot requirement is calculated according to the final color dot requirement, and both the first quantum dot film and the second quantum dot film occupy a certain proportion. For example, the total red and green quantum dots content of the first quantum dot film accounts for 0.1-50%, 0.1-40%, or 0.1-30% of the total quantum dot requirement mass, which is more conducive to reducing thickness-color dot fluctuation.

[0069] A third aspect of this application provides a backlight module comprising the quantum dot light conversion film of any of the above-mentioned claims. The aforementioned backlight module can be used in display devices such as televisions, mobile phones, tablets, monitors, and laptop screens; the ultra-thin quantum dot light conversion film is particularly suitable for mobile phones.

[0070] The implementation methods are described in more detail below with reference to specific embodiments. However, these are exemplary embodiments of the present disclosure, and the present disclosure is not limited thereto.

[0071] Example 1

[0072] I. Preparation of the Second Quantum Dot Film

[0073] 1. Preparation of quantum dot masterbatch

[0074] Red quantum dot masterbatch (2%): 200g of red quantum dot powder (PL 622nm peak wavelength, fluorescence half-peak width 24nm), 20g of antioxidant 1010, and 9780g of polyethylene terephthalate particles were mixed and stirred evenly, and then extruded, granulated, and dried by twin-screw extrusion at 275℃.

[0075] Green quantum dot masterbatch (2%): 200g of green quantum dot powder (PL532nm peak wavelength, fluorescence half-peak width 24nm), 20g of antioxidant 1010, and 9780g of polyethylene terephthalate were mixed and stirred evenly, and then extruded, granulated, and dried by twin-screw extrusion at 275℃.

[0076] 2. Membrane preparation

[0077] Prepare 775g PET particles, 100g red quantum dot masterbatch, 100g green quantum dot masterbatch, 20g diffused titanium dioxide particles (D50 of 0.4μm), and 5g antioxidant 1010. Use a single-screw extruder with a screw diameter of 75mm and a screw speed of 30 rpm; heating temperature is 275℃. After co-extrusion through a die, roll-extrude and cool to set. After die slitting, a second quantum dot film layer is obtained, with a thickness of 50μm. The mass fraction of red quantum dots in the film layer is 0.2%, and the mass fraction of green quantum dots in the film layer is 0.2%. The QY of the second quantum dot film layer is 38%, and the FWHM is 25.5nm.

[0078] II. Second quantum dot film layer, first quantum dot film layer, base film composite

[0079] 1. Preparation of adhesive containing first quantum dots

[0080] Green and red CdSe-based quantum dots dissolved in toluene (the same type of quantum dots as those in the quantum dot masterbatch), 89g of matrix resin methacrylic acid resin, 1g of diffusion particles TiO2 (D50 of 0.5μm), 0.1g of photoinitiator 819, and 10g of diluent acetic acid were mixed. The mass fraction of green quantum dots in the adhesive was 0.15%, and the mass fraction of red quantum dots in the adhesive was 0.15%. After vacuum deoxygenation and nitrogen purging protection, the adhesive was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an adhesive containing the first quantum dots.

[0081] 2. Preparation of composite membranes

[0082] The adhesive containing the first quantum dot is applied through a slit to a PET base film with a barrier layer (base film thickness is 20 μm, WVTR = 0.8 g / m). 2 The first quantum dot layer and the second quantum dot film (50 μm) are bonded together and then exposed to 365 nm UV light. At this time, the adhesive layer containing the first quantum dot is cured under UV light to form the first quantum dot film (20 μm), forming a composite film with a total thickness of 90 μm.

[0083] III. Preparation of Encapsulation Film

[0084] 1. Preparation of Inorganic Oxide Particle Colloidal Solution

[0085] 88.8g of matrix resin methacrylic acid resin, 0.5g of diffused particles TiO2 (D50 of 0.5μm), 0.5g of diffused particles silica (D50 of 0.5μm), 0.2g of photoinitiator 819 and 10g of diluent acetic acid were mixed, with the mass fraction of diffused particles TiO2 being 0.5% and the mass fraction of diffused particles silica being 0.5%. After vacuum deoxygenation and nitrogen purging protection, the mixture was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an inorganic oxide particle colloid.

[0086] 2. Coating and curing:

[0087] An inorganic oxide particle adhesive was applied through a slit onto the composite film (90 μm thick) prepared above, followed by UV irradiation at 390 nm. The inorganic oxide particle adhesive then cured under UV irradiation to form an encapsulation layer (10 μm), resulting in a quantum dot light conversion film with a total thickness of 100 μm. The final quantum dot light conversion film exhibited a QY of 42% and an FWHM of 25 nm.

[0088] Example 2

[0089] I. Preparation of the Second Quantum Dot Film

[0090] 1. The preparation of quantum dot masterbatch is the same as in Example 1.

[0091] 2. Film Preparation: Prepare 671g PET particles, 150g red quantum dot masterbatch, 150g green quantum dot masterbatch, 20g diffused zirconium dioxide particles (D50 of 0.3μm), and 10g antioxidant 626. Use a single-screw extruder with a screw diameter of 75mm and a screw speed of 27 rpm; heating temperature is 270℃. After co-extrusion through a die, roll-extrude and cool to set. After die slitting, the second quantum dot film is obtained, with a thickness of 15μm. The mass fraction of red quantum dots in the film is 0.3%, and the mass fraction of green quantum dots in the film is 0.3%. The QY of the second quantum dot film is 38.5%, and the FWHM is 26nm.

[0092] II. Second quantum dot film layer, first quantum dot film layer, base film composite

[0093] 1. Preparation of adhesive containing first quantum dots

[0094] Dissolved green and red CdSe-based quantum dots (same as in Example 1), 89g of matrix resin methacrylic acid resin, 1g of diffused particles TiO2 (D50 of 0.3μm), 0.1g of photoinitiator 819, and 10g of diluent acetic acid were mixed. The mass fraction of green quantum dots in the adhesive was 0.2%, and the mass fraction of red quantum dots in the adhesive was 0.2%. After vacuum deoxygenation and nitrogen purging protection, the adhesive was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an adhesive containing the first quantum dots.

[0095] 2. Preparation of composite membranes

[0096] A PET base film (15 μm thick) with a barrier layer is bonded together with an adhesive containing the first quantum dots and a second quantum dot film layer, and then exposed to 365 nm UV light. At this time, the adhesive layer containing the first quantum dots is cured under UV light to form the first quantum dot film layer (10 μm), forming a composite film with a total thickness of 40 μm.

[0097] III. Preparation of Encapsulation Film

[0098] 1. Preparation of Inorganic Oxide Particle Colloidal Solution

[0099] 78.8g of matrix resin methacrylic acid resin, 10g of butyl acrylate, 0.6g of diffused zirconium dioxide particles (D50 of 0.3μm), 0.4g of diffused silica particles (D50 of 0.4μm), 0.2g of photoinitiator 819, and 10g of diluent acetic acid were mixed, with the mass fraction of diffused TiO2 particles being 0.6% and the mass fraction of diffused silica particles being 0.4%. After vacuum deoxygenation and nitrogen purging protection, the mixture was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an inorganic oxide particle colloid.

[0100] 2. Coating and curing:

[0101] An inorganic oxide particle adhesive was applied to the composite film (40 μm thick) through a slit, followed by UV irradiation at 390 nm. The inorganic oxide particle adhesive then cured under UV light to form an encapsulation layer (5 μm), resulting in a quantum dot light conversion film with a total thickness of 45 μm. The final quantum dot light conversion film exhibited a QY of 41% and an FWHM of 24 nm.

[0102] Example 3

[0103] I. Preparation of the Second Quantum Dot Film

[0104] 1. The preparation of quantum dot masterbatch is the same as in Example 1.

[0105] 2. Membrane preparation

[0106] Prepare 560g PET particles, 200g red quantum dot masterbatch, 200g green quantum dot masterbatch, 20g diffused titanium dioxide particles (D50 of 0.5μm), and 20g antioxidant 641. Use a single-screw extruder with a screw diameter of 75mm and a screw speed of 35 rpm; heating temperature is 280℃. After co-extrusion through a die, roll-extrude and cool to set. After die slitting, a second quantum dot film layer is obtained, with a thickness of 60μm. The mass fraction of red quantum dots in the film layer is 0.4%, and the mass fraction of green quantum dots in the film layer is 0.4%. The QY of the second quantum dot film layer is 37.5%, and the FWHM is 26nm.

[0107] II. Second quantum dot film layer, first quantum dot film layer, base film composite

[0108] 1. Preparation of adhesive containing first quantum dots

[0109] Green and red CdSe-based quantum dots (same as in Example 1) dissolved in toluene, 89g of matrix resin methacrylic acid resin, 1g of diffused particles TiO2 (D50 of 0.5μm), 0.1g of photoinitiator 819, and 10g of diluent acetic acid were mixed. The mass fraction of green quantum dots in the adhesive was 0.3%, and the mass fraction of red quantum dots in the adhesive was 0.3%. After vacuum deoxygenation and nitrogen purging protection, the adhesive was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an adhesive containing the first quantum dots.

[0110] 2. Preparation of composite membranes

[0111] The adhesive containing the first quantum dots is applied through a slit and bonded to a PET base film with a barrier layer (55 μm thick) and a second quantum dot film layer, followed by UV irradiation at 390 nm. At this point, the adhesive layer containing the first quantum dots cures under UV irradiation to form the first quantum dot film layer (25 μm), resulting in a composite film with a total thickness of 140 μm.

[0112] III. Preparation of Encapsulation Film

[0113] 1. Preparation of Inorganic Oxide Particle Colloidal Solution

[0114] 78.3g of matrix resin methacrylate, 10g of butyl acrylate, 1g of diffused zirconium dioxide particles (D50 of 0.4μm), 0.5g of diffused silica particles (D50 of 0.4μm), 0.2g of photoinitiator 819, and 10g of diluent acetic acid were mixed. The mass fraction of diffused particles TiO2 was 1%, and the mass fraction of diffused silica particles was 0.5%. After vacuum deoxygenation and nitrogen purging protection, the mixture was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an inorganic oxide particle colloid.

[0115] 2. Coating and curing:

[0116] An inorganic oxide particle adhesive was applied to the composite film (140 μm thick) using a doctor blade, followed by UV irradiation at 390 nm. The inorganic oxide particle adhesive then cured under UV light to form an encapsulation film (10 μm thick), resulting in a quantum dot light conversion film with a total thickness of 150 μm. The quantum dot light conversion film has a QY of 41.5% and an FWHM of 25 nm.

[0117] Example 4

[0118] I. Preparation of the Second Quantum Dot Film

[0119] 1. The preparation of quantum dot masterbatch is the same as in Example 1.

[0120] 2. Film Preparation: Prepare 560g PET particles, 300g red quantum dot masterbatch, 100g green quantum dot masterbatch, 20g diffused titanium dioxide particles (D50 of 0.2μm), and 20g antioxidant 1024. Use a single-screw extruder with a screw diameter of 75mm and a screw speed of 35 rpm; heating temperature is 285℃. After co-extrusion through a die, roll-extrude and cool to set. After die slitting, the second quantum dot film is obtained, with a thickness of 50μm. The mass fraction of red quantum dots in the film is 0.6%, and the mass fraction of green quantum dots is 0.2%. The QY of the second quantum dot film is 38%, and the FWHM is 26nm.

[0121] II. Second quantum dot film layer, first quantum dot film layer, base film composite

[0122] 1. Preparation of adhesive containing first quantum dots

[0123] Green and red CdSe-based quantum dots (same as in Example 1) dissolved in toluene, 89g of matrix resin methacrylic acid resin, 1g of diffused particles TiO2 (D50 of 0.2μm), 0.1g of photoinitiator 819, and 10g of diluent acetic acid were mixed. The mass fraction of green quantum dots in the adhesive was 0.7%, and the mass fraction of red quantum dots in the adhesive was 0.3%. After vacuum deoxygenation and nitrogen purging protection, the adhesive was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an adhesive containing the first quantum dots.

[0124] 2. Preparation of composite membranes

[0125] The adhesive containing the first quantum dots is coated in a comma pattern and bonded together with a PET base film (40 μm thick) with a barrier layer and a second quantum dot film layer, followed by UV irradiation at 390 nm. At this point, the adhesive layer containing the first quantum dots cures under UV irradiation to form the first quantum dot film layer (40 μm), forming a composite film with a total thickness of 130 μm.

[0126] III. Preparation of Encapsulation Film

[0127] 1. Preparation of Inorganic Oxide Particle Colloidal Solution

[0128] 77.6g of matrix resin methacrylic acid resin, 10g of butyl acrylate, 1.5g of diffused zirconium dioxide particles (D50 of 0.3μm), 0.7g of diffused silica particles (D50 of 0.4μm), 0.2g of photoinitiator 819, and 10g of diluent acetic acid were mixed, with the mass fraction of diffused zirconium dioxide particles being 1.5% and the mass fraction of diffused silica particles being 0.7%. After vacuum deoxygenation and nitrogen purging protection, the mixture was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an inorganic oxide particle colloid.

[0129] 2. Coating and curing:

[0130] An inorganic oxide particle adhesive was applied through a slit onto the aforementioned composite film (130 μm thick), followed by UV irradiation at 390 nm. The inorganic oxide particle adhesive then cured under UV light to form an encapsulation layer (5 μm), resulting in a quantum dot light conversion film with a total thickness of 135 μm. The quantum dot light conversion film has a QY of 42% and an FWHM of 25.5 nm.

[0131] Example 5

[0132] I. Preparation of the Second Quantum Dot Film

[0133] 1. The preparation of quantum dot masterbatch is the same as in Example 1.

[0134] 2. Film Preparation: Prepare 560g PET particles, 100g red quantum dot masterbatch, 300g green quantum dot masterbatch, 20g diffused titanium dioxide particles (D50 of 0.15μm), and 20g antioxidant 1024. Use a single-screw extruder with a screw diameter of 75mm and a screw speed of 32 rpm; heating temperature is 290℃. After co-extrusion through a die, roll-extrude and cool to set. After die slitting, the second quantum dot film is obtained, with a thickness of 50μm. The mass fraction of red quantum dots in the film is 0.2%, and the mass fraction of green quantum dots is 0.6%. The QY of the second quantum dot film is 37%, and the FWHM is 25.5nm.

[0135] II. Second quantum dot film layer, first quantum dot film layer, base film composite

[0136] 1. Preparation of adhesive containing first quantum dots

[0137] Green and red CdSe-based quantum dots dissolved in toluene (quantum dots are the same as in Example 1), 89g of matrix resin methacrylic acid resin, 1g of diffused particles TiO2 (D50 is 0.15μm), 0.1g of photoinitiator 819 and 10g of diluent acetic acid were mixed. The mass fraction of green quantum dots in the adhesive was 0.3% and the mass fraction of red quantum dots in the adhesive was 0.7%. After vacuum deoxygenation and nitrogen purging protection, the adhesive was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an adhesive containing the first quantum dots.

[0138] 2. Preparation of composite membranes

[0139] The adhesive containing the first quantum dots is applied through a slit and bonded to a PET base film with a barrier layer (40 μm thick) and a second quantum dot film layer, followed by UV irradiation at 390 nm. At this point, the adhesive layer containing the first quantum dots cures under UV irradiation to form the first quantum dot film layer (40 μm), resulting in a composite film with a total thickness of 130 μm.

[0140] III. Preparation of Encapsulation Film

[0141] 1. Preparation of Inorganic Oxide Particle Colloidal Solution

[0142] 77.6g of matrix resin methacrylic acid resin, 10g of butyl acrylate, 1.5g of diffused zirconium dioxide particles (D50 of 0.3μm), 0.7g of diffused silica particles (D50 of 0.4μm), 0.2g of photoinitiator 819, and 10g of diluent acetic acid were mixed, with the mass fraction of diffused zirconium dioxide particles being 1.5% and the mass fraction of diffused silica particles being 0.7%. After vacuum deoxygenation and nitrogen purging protection, the mixture was stirred at a speed of 50-300 rpm for 1-3 hours to obtain an inorganic oxide particle colloid.

[0143] 2. Coating and curing:

[0144] An inorganic oxide particle adhesive was applied to the composite film (130 μm thick) via slit coating, followed by UV irradiation at 390 nm. The inorganic oxide particle adhesive then cured under UV irradiation to form an encapsulation layer (5 μm), resulting in a quantum dot light conversion film with a total thickness of 135 μm. The quantum dot light conversion film has a QY of 42.5% and an FWHM of 24.5 nm.

[0145] Comparative Example 1

[0146] Quantum dot light conversion film prepared by coating method

[0147] 1. Preparation of adhesive containing sub-dots:

[0148] Green and red CdSe-based quantum dots (same as in Example 1) dissolved in toluene, 89g of methacrylic acid resin, 1g of diffused TiO2 particles (D50 of 0.5μm), 0.1g of photoinitiator 819 and 10g of diluent acetic acid were mixed, wherein the mass fraction of green quantum dots in the adhesive was 0.22% and the mass fraction of red quantum dots in the adhesive was 0.22%.

[0149] 2. Apply and cure

[0150] The quantum dot adhesive was applied through a slit-gluing process and bonded to two PET base films with barrier layers (same as in Example 1, each film being 20 μm thick), followed by UV irradiation at 390 nm. During this process, the intermediate adhesive layer cured under UV irradiation to form a quantum dot layer (60 μm thick), resulting in a quantum dot light conversion film with a total thickness of 100 μm. The quantum dot light conversion film has a QY of 36% and an FWHM of 26 nm.

[0151] Comparative Example 2

[0152] Quantum dot PET film preparation by extrusion

[0153] 1. The preparation of quantum dot masterbatch is the same as in Example 1.

[0154] 2. Film Preparation: Prepare 775g PET particles, 100g red quantum dot masterbatch, 100g green quantum dot masterbatch, 20g diffused titanium dioxide particles (D50 of 0.4μm), and 5g antioxidant 1010. Use a single-screw extruder with a screw diameter of 75mm and a screw speed of 30 rpm; heating temperature is 275℃. After co-extrusion through a die, roll-extrude and cool to set. After die slitting, obtain a quantum dot PET film with a thickness of 100μm. The mass fraction of red quantum dots in the film is 0.13%, and the mass fraction of green quantum dots in the film is 0.13%. The quantum dot PET film has a QY of 35% and an FWHM of 26nm.

[0155] The red and green quantum dots and the base film used in the above comparative and examples are the same. The results of the examples and comparative examples are shown in Table 1. |△Y|max or |△X|max represents the color dot non-uniformity, which is tested before the start of the film aging experiment. The color dot uniformity, quantum efficiency, and film hardness were all tested according to the national standard method; the aging test conditions were: temperature 60℃, relative humidity 90%, and received light power 20W / m. 2 For trends in brightness and color point changes, please refer to [link / reference]. Figure 3 The brightness decrease and color point change trend of Example 1 were the slowest. As shown in the table below, the stability of Example 1 is higher than that of Comparative Example 1, and its performance in all aspects is better. The color point uniformity of Comparative Example 2 is worse, and the film stability is poor because the quantum dots are not well protected.

[0156] Table 1

[0157]

[0158]

[0159] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A quantum dot light conversion film, characterized by, The quantum dot light conversion film comprises a base film, a first quantum dot film layer, a second quantum dot film layer and an encapsulation film layer arranged in sequence; the base film comprises a barrier film layer and a PET film layer, the barrier property of the base film is WVTR≤2g / (m 2 day); the first quantum dot film layer comprises first quantum dots and a first resin, the second quantum dot film layer comprises second quantum dots and polyethylene terephthalate, the encapsulation film layer comprises a second resin and inorganic oxide particles, the first quantum dots and the second quantum dots are selected from one or both of red quantum dots and green quantum dots; the mass fraction of the red quantum dots and the green quantum dots in the first quantum dot film layer is 0.01-1%; the refractive index of the first resin is lower than the refractive index of the PET film layer, the refractive index of the first resin is between 1.38-1.6, and the refractive index of the encapsulation film layer is higher than the first resin; the preparation method of the quantum dot light conversion film comprises: melt co-extruding a composition containing the second quantum dots and polyethylene terephthalate particles to obtain a single-layer or multi-layer second quantum dot film layer; preparing the base film and glue containing the first quantum dots; using a coating device to coat the glue containing the first quantum dots between the base film and the second quantum dot film layer, and curing to obtain an intermediate, the intermediate comprises a base film, the first quantum dot film layer and the second quantum dot film layer arranged in sequence; coating glue containing the inorganic oxide particles on the second quantum dot film layer, and curing to obtain the encapsulation film layer, and finally obtaining the quantum dot light conversion film.

2. The quantum dot light converting film of claim 1, wherein, The mass fraction of the red quantum dots and the green quantum dots in the second quantum dot film layer is 0.01-20%.

3. The quantum dot light converting film of claim 1, wherein, The first quantum dot film layer and the second quantum dot film layer further comprise second diffusion particles.

4. The quantum dot light converting film of claim 1, wherein, The thickness of the first quantum dot film layer is 1-100µm; the thickness of the second quantum dot film layer is 6-250µm.

5. The quantum dot light converting film of claim 1, wherein, The thickness of the base film is 12-125µm, and the thickness of the encapsulation film layer is 0.5-25µm.

6. The quantum dot light converting film of claim 1, wherein, The thickness of the quantum dot light conversion film is 37.5-75µm.

7. The quantum dot light converting film of claim 1, wherein, The second resin material comprises one or more of an acrylic resin, an epoxy resin, and a silicone resin, and the inorganic oxide particles are selected from one or more of zirconium oxide, titanium oxide, and silicon oxide.

8. The quantum dot light converting film of claim 1, wherein, The first quantum dot film layer has a fluorescence half-peak width of less than or equal to 25nm and an external quantum efficiency of greater than or equal to 40%.

9. The quantum dot light converting film of claim 1, wherein, The second quantum dot film layer has a fluorescence half-peak width of greater than or equal to 25nm and an external quantum efficiency of less than 40%.

10. The quantum dot light converting film of claim 1, wherein, The second quantum dot-containing composition comprises red quantum dot master batches, green quantum dot master batches, diffusion master batches, stabilizers, and antioxidants.

11. A backlight module, characterized in that, The quantum dot light conversion film comprises the quantum dot light conversion film of any one of claims 1-10.

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