High-stiffness quantum dot diffusion film

Abstract

The utility model discloses a high-stiffness quantum dot diffusion film, and belongs to the technical field of display devices. The high-stiffness quantum dot diffusion film comprises a quantum dot adhesive layer and composite functional layers symmetrically arranged on the two sides of the quantum dot adhesive layer in an attached mode. The composite functional layer comprises an extrusion type PET diffusion film layer and a barrier layer deposited on the extrusion type PET diffusion film layer; and one surface of the barrier layer of the composite functional layer is attached and fixed to the quantum dot adhesive layer. Compared with a base material of a coating diffusion barrier film and a barrier film applied at present, the extrusion type diffusion barrier film has the advantages that the comprehensive cost is greatly reduced; the high-stiffness quantum dot diffusion film is provided with an efficient water sample blocking layer, so that quantum dots are prevented from losing efficacy, the service life is longer, and no failure risk exists; when the high-stiffness quantum dot diffusion film is applied to liquid crystal backlight, a common diffusion plate is not needed, the high-stiffness quantum dot diffusion film can be attached to a brightness enhancement film, a common diffusion film and other optical films for use, the liquid crystal backlight assembly process is simplified, and the cost is reduced.

Description

Technical Field

[0001] The present application relates to a high-stiffness quantum point diffusion film, belonging to the technical field of display devices. Background Art

[0002] Backlight modules provide a uniform light source for liquid crystal displays (LCDs). Based on the placement of the light source, backlight modules are categorized as either edge-lit or direct-lit. In edge-lit modules, LEDs are arranged around a light guide plate (LGP), which transforms the linear LED strip light source into a surface light source. A diffuser film positioned above the LGP evenly distributes the backlight. In direct-lit modules, LEDs are positioned below the diffuser plate, which transforms the scattered LED light source into a uniform surface light source. This offers significant advantages in backlight brightness, brightness uniformity, zoned light control, and energy efficiency. Mini LED backlights, a recently emerging technology, are an improved direct-lit LED backlight technology. By using smaller LEDs, more LEDs can be arranged within the same area, enabling more precise backlight control. This significantly improves the contrast of LCDs and enables high dynamic range displays. Combined with quantum dot light conversion technology, this further enhances the screen's color gamut, achieving more vivid and lifelike colors, rivaling current OLED displays.

[0003] The diffuser plates that are widely used now mainly adopt the melt extrusion process, which heats high molecular polymers such as polystyrene (PS) and polymethyl methacrylate (PMMA) to a molten state, then extrudes them into plates through an extruder, and then stretches them to obtain products of specific sizes. There are two main preparation technologies for diffusion films. One is to add light-diffusing particles into the optical resin, and the other is to coat the light-diffusing particles on the surface of the material. Based on the diffusion principle and compatibility factors, the light diffusion effect of existing additive or coating diffusion films is limited. As the proportion of organic diffusing agents increases, light loss increases, and inorganic light loss is even greater. Therefore, the existing diffusion film technology has a situation where the diffusion effect and transmittance are mutually restricted.

[0004] Quantum dot diffuser film is a thin film structure that encapsulates quantum dots between two layers of diffuser film. In addition to its light diffusion function, it can also convert blue backlight into high-purity red and green light, achieving a uniform white backlight. It can directly replace conventional diffuser films in backlight systems. Quantum dots are susceptible to water and oxygen intrusion during use, which can damage their surface structure, affecting their luminous efficiency and causing color cast. Therefore, an ultra-thin water and oxygen barrier film is applied to the surfaces of both diffuser layers to reduce water and oxygen intrusion and extend the life of the quantum dot diffuser film.

[0005] Quantum dot diffuser panels typically have a sandwich structure, manufactured using a three-layer co-extrusion process. The panels are formed from a PS or PMMA polymer substrate on both sides, while the middle layer is a combination of quantum dot material and PS or PMMA particles, melt-extruded together. The quantum dots are evenly dispersed within the polymer layer. Due to the lack of an effective barrier layer, the lifespan of quantum dot diffuser panels is significantly lower than that of quantum dot diffuser films, making them difficult to meet the lifespan requirements of display devices. Utility Model Content

[0006] To solve the following problems existing in the prior art of LCD backlight modules: quantum dot diffusion plates have no barrier layer, have poor long-term stability, and have a high risk of failure of the entire device; quantum dot materials undergo a high-temperature melt extrusion process above 220°C, which easily leads to reduced luminous efficiency or even failure of the quantum dot materials, and the cost of quantum dot diffusion plates is relatively high (about 45 to 60 yuan / ㎡); quantum dot diffusion films in the prior art can only be used above light guide plates or diffusers and cannot be used independently in direct-lit backlights because the light diffusion effect and stiffness do not meet application requirements, and the cost of quantum dot diffusion films is very high (about 85 to 120 yuan / ㎡). The present application provides a high-stiffness quantum dot diffusion film, which uses a low-cost extruded diffusion barrier film as a substrate, disperses quantum dot materials into a photocurable glue as a quantum dot glue, and applies a certain thickness of quantum dot glue between two layers of extruded barrier diffusion films. After photocuring, a quantum dot diffusion film with high stiffness is obtained, which replaces the quantum dot diffusion plate and is applied in direct-lit backlights to reduce or avoid the problems existing in the prior art.

[0007] This application adopts the following technical solutions:

[0008] A high-stiffness quantum dot diffusion film, comprising a quantum dot glue layer and a composite functional layer symmetrically laminated on both sides of the quantum dot glue layer;

[0009] The composite functional layer includes an extruded PET diffusion film layer and a barrier layer deposited on the extruded PET diffusion film layer;

[0010] One side of the barrier layer of the composite functional layer is adhered and fixed to the quantum dot glue layer.

[0011] Optionally, the extruded PET diffusion film layer includes a co-extruded diffusion functional layer and a PET optical layer.

[0012] Optionally, the diffusion functional layer and / or the PET optical layer is a foamed PET film.

[0013] Based on the analysis of the diffusion principle, the use of bubble capsule microspheres instead of organic and inorganic diffusion particles will achieve the maximum refractive index difference between the main resin and the diffusion particles, achieve the highest diffusion effect, and at the same time, the bubble capsule light loss is minimal, which can simultaneously meet the requirements of ideal diffusion effect and transmittance. Based on this, the present invention uses an extruded diffusion film as a substrate, combines atomic layer deposition technology to prepare an efficient water and oxygen barrier layer, and prepares a quantum dot diffusion film with high stiffness characteristics. This high-stiffness quantum dot diffusion film can directly replace the diffuser in the backlight, while realizing the functions of light diffusion and quantum dot light conversion. Compared with the aforementioned quantum dot diffusion plate, it has lower cost, higher backlight brightness, and contains a water and oxygen barrier layer that can significantly improve service life.

[0014] A water and oxygen barrier layer is directly deposited on one side of the extruded diffusion membrane as the substrate. The extruded barrier diffusion membrane is prepared by melt extrusion and biaxial stretching. Combined with the foaming process, a porous microstructure is prepared inside the diffusion membrane. It not only improves the problems of uneven brightness, shedding of diffusion particles, easy friction, and severe warping of traditional diffusion membranes, but also has light transmittance, haze, ink adhesion, and surface impedance that are not lower than those of traditional diffusion membranes.

[0015] Optionally, the extruded PET diffusion film layer consists of a diffusion functional layer and a PET optical layer;

[0016] Alternatively, it is composed of a diffusion function layer and two PET optical layers symmetrically arranged on both sides of the diffusion function layer.

[0017] Optionally, the diffusion function layer is a PET film layer containing diffusion particles.

[0018] Optionally, the thickness of the extruded PET diffusion film is 50 μm to 500 μm.

[0019] Optionally, the diffusion function layer has a thickness of 50 μm to 500 μm.

[0020] Optionally, the quantum dot glue layer is a colloidal thin film layer formed by curing a UV curable glue in which quantum dot powder particles and quantum dot diffusion particles are dispersed.

[0021] The materials of the quantum dot powder particles and the quantum dot diffusion particles in the present application are not strictly limited, and those skilled in the art can select according to their needs. For example, the quantum dot powder particles are selected from at least one of quantum dot particles, composite particles of quantum dots and polymers or inorganic oxides, and the material of the quantum dot diffusion particles is selected from at least one of titanium dioxide, silicon dioxide, and zirconium oxide; the quantum dots in the quantum dot powder are selected from IV, II-VI, IV-VI, III-V group quantum dots and multi-element quantum dots; the quantum dots in the quantum dot powder are selected from at least one of carbon-containing quantum dots, silicon quantum dots, germanium quantum dots, cadmium sulfide quantum dots, cadmium selenide quantum dots, cadmium telluride quantum dots, zinc selenide quantum dots, lead sulfide quantum dots, lead selenide quantum dots, indium phosphide quantum dots, indium arsenide quantum dots, inorganic perovskite quantum dots and organic-inorganic hybrid perovskite quantum dots.

[0022] Optionally, the thickness of the quantum dot glue layer is 30 to 150 μm.

[0023] Optionally, the barrier layer is a metal oxide deposition layer.

[0024] The material of the barrier film is selected from at least one of Al2O3, TiO2, HfO2, and ZrO2.

[0025] Optionally, the barrier film has a thickness of 10 nm to 1000 nm.

[0026] In this application, the preparation method of the extruded PET diffusion film and the deposition method of the barrier layer are not strictly limited. Those skilled in the art can produce the film according to existing technologies. The barrier layer can be formed by depositing a dense oxide film on the surface of the film using PVD / CVD / ALD techniques to achieve a highly effective water and oxygen barrier effect, thereby eliminating the composite costs of traditional barrier films. The barrier layer is deposited on the surface of the extruded PET diffusion film and used as a substrate. Quantum dot concentrate or quantum dot powder is uniformly blended with UV glue to form quantum dot UV glue. A predetermined thickness of quantum dot UV glue is applied between the two layers of extruded PET diffusion film with a barrier layer. After UV light curing, roll-to-roll continuous production can be achieved.

[0027] This application utilizes a low-cost extruded PET diffuser film as the diffusion layer. Compared to traditional diffusers that enhance light diffusion by coating with organic or inorganic diffuser particles, this film utilizes a porous microstructure created by extrusion technology on the surface of the PET intermediate layer. This not only improves the problems of uneven brightness, diffuser particle shedding, easy friction, and severe warping associated with traditional diffusers, but also maintains comparable light transmittance, haze, ink adhesion, and surface impedance to traditional diffusers. In addition to its cost advantage, the extruded PET diffuser film also offers high stiffness and resistance to collapse, resulting in better diffusion and more uniform brightness for LEDs.

[0028] The beneficial effects of this application include:

[0029] The high-stiffness quantum point diffusion film provided in the present application uses an extruded diffusion barrier film, which has a significantly lower overall cost than the substrate of the currently used coated diffusion film laminated with the barrier film; the high-stiffness quantum point diffusion film is provided with a high-efficiency water-like barrier layer to prevent quantum dot failure, has a longer service life, and has no risk of failure; when the high-stiffness quantum point diffusion film is used in liquid crystal backlights, no ordinary diffusion plate is required, and it can be laminated with optical films such as brightening films and ordinary diffusion films, thereby simplifying the liquid crystal backlight assembly process and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the structure of a three-layer extruded PET diffusion film with a barrier layer in this application.

[0031] Figure 2 This is a schematic diagram of the structure of a two-layer extruded PET diffusion film with a barrier layer in this application.

[0032] Figure 3 This is a schematic structural diagram of the high stiffness quantum point diffusion membrane of this application.

[0033] Figure 4 It is the fluorescence spectrum of high stiffness quantum point diffusion film.

[0034] Figure 5 These are the reliability test results of high-stiffness quantum point diffusion film, where (a) is the film brightness decay curve with test time, and (b) is the film color coordinate decay curve with test time.

[0035] Figure ID

[0036] 11. Quantum dot adhesive layer; 12. First barrier layer; 13. First extruded PET diffusion film; 14. Second barrier layer; 15. Second extruded PET diffusion film. DETAILED DESCRIPTION

[0037] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0038] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0039] Unless otherwise specified, conventional methods were used for testing, and instrument settings were those recommended by the manufacturer.

[0040] Example 1 Three-layer extruded PET diffusion film with barrier layer

[0041] Three-layer extruded PET diffusion film structure with barrier layer, such as Figure 1As shown, the device comprises an extruded PET diffusion film layer and a barrier layer deposited on the extruded PET diffusion film layer. The extruded PET diffusion film layer comprises a diffusion functional layer and two PET optical layers symmetrically arranged on either side of the diffusion functional layer. The diffusion functional layer is a PET film layer containing diffusion particles, and the barrier layer is a metal oxide deposited layer.

[0042] The preparation steps of the three-layer extruded PET diffusion membrane structure with a barrier layer all adopt existing technologies, and the steps are as follows:

[0043] Step 1: Roll a three-layer extruded diffusion membrane with a thickness of 250 μm and place it in the reaction chamber of the atomic layer deposition system so that the gas flows directly through the surface of the substrate layer.

[0044] Step 2: Nitrogen is introduced into the atomic layer deposition (ALD) system as a carrier gas and a mechanical vacuum pump is turned on to evacuate the ALD reaction chamber, controlling the pressure at 100 Pa; the reaction chamber temperature is controlled at 70°C by heating with an electric heating tape, and the temperatures of trimethylaluminum (TMA) and water (H2O) are at room temperature.

[0045] Step 3: First, a first layer of aluminum oxide (Al2O3) inorganic barrier layer is deposited on the surface of the bottom layer of the extruded diffusion membrane, and 100 cycles are deposited in total. Each cycle includes the following four steps: (1) The first precursor TMA is injected into the reaction chamber to react chemically with the surface of the foaming diffusion membrane base layer and replace the hydroxyl (-OH) functional group on the surface of the foaming diffusion membrane base layer. The specific chemical reaction formula is as follows: -OH+Al(CH3)3→-O-Al(CH3)2+CH4; (2) Nitrogen is introduced to purge unreacted TMA and by-products; (3) Water vapor is injected into the reaction chamber to react with the adsorbed TMA on the surface of the foaming diffusion membrane base layer to replace the surface functional groups again. The specific chemical reaction formula is as follows: -O-Al(CH3)2+H2O→-OAl-OH+CH4; Nitrogen is introduced to purge unreacted H2O and by-products.

[0046] According to the steps (1) to (3) above, the pulse sequence for atomic layer deposition of the Al2O3 inorganic barrier layer is represented by t1-t2-t3-t4, where t1 is the injection time of the TMA precursor, t3 is the injection time of the H2O precursor, and t2 and t4 are the nitrogen purge times. The pulse sequence used in this example is 10s-20s-10s-20s. After 100 cycles, the Al2O3 inorganic barrier film thickness is approximately 20nm.

[0047] The barrier film can achieve a water vapor transmission rate of 1×10 -1 g / m 2 / 24h, oxygen transmission rate is 1×10g / m 2 / 24h.

[0048] Example 2 Two-layer extruded PET diffusion film with barrier layer

[0049] Two-layer extruded PET diffusion film structure with barrier layer, such as Figure 2 As shown, it includes an extruded PET diffusion film layer and a barrier layer deposited on the extruded PET diffusion film layer, and the extruded PET diffusion film layer consists of a diffusion functional layer and a PET optical layer.

[0050] The preparation process is the same as that of Example 1, except that the structure of the extruded diffusion membrane is different.

[0051] Example 3 High Stiffness Quantum Point Diffusion Film

[0052] High stiffness quantum point diffusion film structure, such as Figure 3 As shown, it comprises a quantum dot adhesive layer and composite functional layers symmetrically laminated on either side of the quantum dot adhesive layer. The composite functional layer comprises an extruded PET diffusion film layer and a barrier layer deposited on the extruded PET diffusion film layer. One side of the barrier layer of the composite functional layer is laminated and fixed to the quantum dot adhesive layer. The diffusion functional layer is a PET film layer containing diffusion particles, the barrier layer is a metal oxide deposition layer, and the quantum dot adhesive layer is a colloidal film layer formed by curing a UV-curable adhesive containing dispersed quantum dot powder particles and quantum dot diffusion particles.

[0053] The steps for preparing the high stiffness quantum point diffusion membrane structure all adopt existing technologies, and the steps are as follows:

[0054] The following perovskite quantum dot powder was prepared by referring to the method of the embodiment in the patent publication number CN 114437710 A and changing the type of polymer: 140g of FAPbBr3 perovskite quantum dot-coated PMMA polymer micropowder (Example 10, in which the polymer matrix was switched from PVDF to PMMA), 50g of CsPbBrI2 perovskite quantum dot-coated PMMA polymer micropowder (Example 14) were mixed with 1000g of UV glue to form a UV-curable quantum dot coating liquid. The barrier layers of two extruded PET diffusion films with a thickness of 250um were placed opposite each other, and the quantum dot coating liquid was applied between the barrier layers of the two extruded PET diffusion films through a slit coater and photocured (UV light source curing energy 1000mJ / cm 2 ) forms a quantum dot layer (QD layer) with a thickness of 60 μm to obtain a high-stiffness quantum dot diffusion film with a structure such as Figure 3 As shown, the quantum dot diffusion film (1) is sequentially stacked from one side to the other side to form a first extruded PET diffusion film (13), a first barrier layer (12), a quantum dot glue layer (11), a second barrier layer (14), and a second extruded PET diffusion film (15).

[0055] The components of the UV glue include: 50g of polyurethane acrylate oligomer, 21g of di-trimethylolpropane tetraacrylate, 650g of tricyclodecane dimethanol diacrylate, 50g of isobornyl acrylate, 20g of photoinitiator 1173, and 20g of photoinitiator TPO-L.

[0056] When the extruded PET diffusion film is an extruded foamed PET diffusion film, it has better stiffness.

[0057] The high stiffness quantum point diffusion film emits high purity red and green light under the stimulation of blue LED backlight, and the fluorescence spectrum is as follows Figure 4 As shown, it forms a white backlight with a blue LED light source. The high-stiffness quantum point diffuser film was placed in a high-temperature, high-humidity environment at 50°C and 85% RH, and then exposed to a blue LED backlight with a light intensity of 170W / ㎡ for accelerated aging testing. The curves showing how the brightness and color coordinates of the high-stiffness quantum point diffuser film change with the accelerated aging test time are shown in Figure 2. Figure 5 As shown, the brightness attenuation is less than 10% and the color point change is less than 15‰, which meets the needs of industrial applications.

[0058] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A high stiffness quantum point diffusion film, characterized in that: It includes a quantum dot glue layer and a composite functional layer symmetrically arranged on both sides of the quantum dot glue layer; The composite functional layer includes an extruded PET diffusion film layer and a barrier layer deposited on the extruded PET diffusion film layer; One side of the barrier layer of the composite functional layer is adhered and fixed to the quantum dot glue layer.

2. The high stiffness quantum point diffusion film according to claim 1, characterized in that: The extruded PET diffusion film layer comprises a co-extruded diffusion functional layer and a PET optical layer.

3. The high stiffness quantum point diffusion film according to claim 2, characterized in that: The extruded PET diffusion film layer consists of a diffusion functional layer and a PET optical layer; Alternatively, it is composed of a diffusion function layer and two PET optical layers symmetrically arranged on both sides of the diffusion function layer.

4. The high stiffness quantum point diffusion film according to claim 2, characterized in that: The diffusion function layer is a PET film layer containing diffusion particles.

5. The high stiffness quantum point diffusion film according to claim 2, characterized in that: The thickness of the extruded PET diffusion film is 50μm to 500μm.

6. The high stiffness quantum point diffusion film according to claim 2, characterized in that: The thickness of the diffusion function layer is 50 μm to 500 μm.

7. The high stiffness quantum point diffusion film according to claim 1, characterized in that: The quantum dot glue layer is a colloidal film layer formed by curing a UV curing glue in which quantum dot powder particles and quantum dot diffusion particles are dispersed.

8. The high stiffness quantum point diffusion film according to claim 1, characterized in that: The thickness of the quantum dot glue layer is 30 to 150 μm.

9. The high stiffness quantum point diffusion film according to claim 1, characterized in that: The barrier layer is a metal oxide deposition layer.

10. The high stiffness quantum point diffusion film according to claim 1, characterized in that: The thickness of the barrier layer is 10 nm to 1000 nm.

Images