PS quantum dot composite microstructure diffusion plate

Abstract

The invention belongs to the technical field of light diffusion plates, and discloses a PS quantum dot composite microstructure diffusion plate. According to the method, the composite board is prepared through a three-layer co-extrusion process, the board comprises an upper PS diffusion layer, a middle quantum dot layer and a lower Rayleigh scattering layer, and the lower Rayleigh scattering layer contains titanium dioxide particles with specific concentration to achieve the Rayleigh scattering effect. The Rayleigh scattering layer can effectively scatter a blue light part in incident white light in the plate and enhance the blue light part to the middle quantum dot layer, so that the excitation efficiency of quantum dots is remarkably improved, the color gamut and contrast ratio of a display device are further improved, and meanwhile, the original light transmittance of the plate is basically kept. The prepared diffusion plate is suitable for the display field with high requirements on color expression, such as a television backlight module.

Description

Technical Field

[0001] The present invention belongs to the field of diffusion plates, and in particular relates to a method for preparing a PS quantum dot composite microstructure diffusion plate. Background Art

[0002] Polystyrene (PS) resin offers excellent impact resistance, rigidity, and dimensional stability, effectively supporting core components such as TV screen modules and motherboards. It can also be easily injection-molded into complex structures, meeting the lightweight and precision design requirements of backplanes. Among commonly used optical plastics, PS resin offers outstanding performance at a relatively low price. It possesses high mechanical strength and good compatibility with conventional rubber and resin materials, offering significant potential for modification. Compared to metal or other engineering plastics, PS raw materials are inexpensive, and the processing technology is mature, making it suitable for large-scale production and significantly reducing TV manufacturing costs. Currently, it is widely used in TV backplanes.

[0003] As consumers' demands for television picture quality continue to rise, high color gamut and high contrast have become key developments in display technology. Quantum dot (QD) technology, due to its excellent photoluminescent properties, is widely used to enhance the color gamut of display devices. The use of quantum dot materials requires the use of blue light as the light source in the backlight module, which also requires changes to the optical film and diffuser, increasing costs. To reduce costs, mainstream OEMs currently use existing white light backlight structures and replace them with low-concentration quantum dot panels to improve color gamut. However, in existing systems using white LEDs as backlights, the excitation efficiency of blue light on quantum dots still needs to be improved. The blue light in white light often fails to excite the quantum dots with sufficient intensity, resulting in weak red and green light conversion, and failing to fully realize the color gamut-enhancing potential of quantum dots. Some technologies attempt to increase optical path length by increasing scattering. For example, CN202010392054.2 mentions a quantum dot light-scattering particle complex, and CN201810265373.X mentions a functional blue light blocking layer that reflects blue light to re-excite the quantum dots, and mentions titanium dioxide as a light-diffusing particle. However, these solutions mainly use titanium dioxide as a conventional diffuser, or simply reflect blue light, and fail to fully optimize the utilization path of blue light in white light inside the plate to specifically enhance quantum dot excitation.

[0004] Therefore, building on the proven PS diffuser plate, how to further enhance the excitation efficiency of quantum dots through innovative structural and material design, thereby improving the color gamut and contrast of the final product, is a pressing challenge in the industry. This invention aims to enhance the excitation of quantum dots by introducing a Rayleigh scattering layer and employing a microstructure to more effectively manage and utilize blue light within the plate. Summary of the Invention

[0005] In response to the problems in the background technology, the present invention provides a method for preparing a PS quantum dot composite microstructure diffuser plate. While maintaining the transmittance of the diffuser plate unchanged, the Rayleigh scattering layer is used to pre-separate a portion of blue light (i.e., the blue light portion of the white light is preferentially scattered and partially directed / reflected back to the middle quantum dot layer) to excite the quantum dots contained in the quantum dot layer, thereby improving the color gamut and contrast.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: A PS quantum dot composite microstructure diffuser plate comprises the following steps: Prepare the raw materials of the three-layer structure according to the following weight parts: Upper layer (PS diffusion layer): 90-100 parts PS resin, 2-10 parts diffusion masterbatch, 0.1-1 parts additives; Middle layer (quantum dot layer): 50-100 parts of PS resin, 6-40 parts of quantum dot masterbatch, 0.1-10 parts of diffusion masterbatch, 0.1-1 parts of additives; the quantum dot masterbatch contains 3-15 parts of red quantum dot masterbatch and 3-25 parts of green quantum dot masterbatch.

[0007] Lower layer (Rayleigh scattering layer): 95-100 parts of PS resin, 1-5 parts of nano-titanium dioxide masterbatch, and 0.1-1 parts of additives; Furthermore, the weight percentage ranges of the components of the diffusion masterbatch are: 3-20% of the silicone diffusing agent; 80-97% of the base resin PS; 0.2-1% of the antioxidant; and 0.2-1% of the lubricant.

[0008] Furthermore, the nano titanium dioxide masterbatch comprises the following components by mass percentage: titanium dioxide 0.5-2%, base resin PS 97-99%, and processing aid (one of white oil, silicone oil, and naphthenic oil) 0.1-1%.

[0009] Furthermore, Rayleigh scattering requires that the diameter of small particles be 1 to 300 nm, and preferably, titanium dioxide with a diameter of 10 to 50 nm is used in the nano-titanium dioxide masterbatch.

[0010] Furthermore, the quantum dots contained in the quantum dot masterbatch are selected from one or more of CdSe-based quantum dots, CdTe-based quantum dots, PbS-based quantum dots, perovskite quantum dots, and carbon-based quantum dots.

[0011] The red quantum dot masterbatch has an absorbance of 200 OD / kg, while the green quantum dot masterbatch has an absorbance of 40 OD / kg. The quantum dot content is 50 OD / g, with red quantum dots accounting for 400 g / 100 kg and green quantum dots for 80 g / 100 kg. The masterbatch is based on PS resin.

[0012] Furthermore, the auxiliary agent is selected from one of a processing aid, an anti-aging agent, and a compatibilizer, specifically one or more of paraffin oil, cyclohexane oil, silicone oil, antioxidant 1076, antioxidant 168, antioxidant 1010, ethylene-vinyl acetate copolymer grafted with maleic anhydride, butyl acrylate grafted with maleic anhydride, methyl methacrylate and glycidyl methacrylate copolymer, acrylonitrile-butadiene-styrene plastic grafted with maleic anhydride, glycidyl methacrylate grafted with polystyrene, and polystyrene grafted with maleic anhydride copolymer.

[0013] A method for preparing a PS quantum dot composite diffusion plate, the plate has a three-layer structure, and the specific preparation steps are as follows: S1. Mix and stir the PS resin particles, diffusion masterbatch and additives required for the upper layer to obtain an upper layer mixture; S2. Mix and stir the PS resin particles, quantum dot masterbatch, diffusion masterbatch and additives required for the middle layer to obtain a middle layer mixture; S3, mixing the PS resin particles, titanium dioxide masterbatch and additives required for the lower layer to obtain a lower layer mixture; S4, respectively putting the three mixed materials prepared in S1, S2 and S3 into three extruders for melting, and forming a three-layer composite structure melt by in-mold composite co-extrusion; S5. After the three-layer composite structure is melt-extruded, it is subjected to roller pressing, followed by cooling and shaping to obtain a finished product of a PS quantum dot composite microstructure diffusion plate.

[0014] Furthermore, the temperature of the mixing and stirring treatment in steps S1, S2 and S3 is 10-80°C, the stirring speed is 100-3000 r / min, and the stirring time is 0.5-20 min.

[0015] Furthermore, the melt extrusion temperature in step S4 is 190-270°C.

[0016] Furthermore, in the rolling process described in step S5, the temperature of the upper roller is 70-90°C, the temperature of the middle roller is 100-140°C, and the temperature of the lower roller (microstructure roller) is 70-90°C; the roller linear speed is 1-3m / min, and the thickness of the plate is determined by setting the roller spacing.

[0017] Furthermore, in step S5, a microstructure is formed on the surface of the lower layer, wherein the microstructure is a tooth-like microstructure, and its cross-sectional shape is one or more of a triangle, a quadrilateral, a pentagon, and a hexagon.

[0018] Furthermore, the cooling temperature in step S5 is 20-100°C, and the setting temperature is 80-150°C.

[0019] Preferably, the lower Rayleigh scattering layer is combined with its surface microstructure to work synergistically to effectively scatter and partially intercept the blue light in the incident white light inside the plate structure, and guide the scattered blue light to the middle quantum dot layer, thereby enhancing the excitation efficiency of the quantum dots and improving the color gamut.

[0020] In summary, this application has the following beneficial effects: First, by adding a quantum dot layer and a microstructure Rayleigh scattering layer, and by setting a microstructure Rayleigh scattering layer in the lower layer, the present application utilizes the synergistic effect of Rayleigh scattering characteristics and microstructure to more effectively scatter and separate the blue light in the incident white light inside the plate, and more effectively guide this part of the blue light to the middle quantum dot layer, thereby stimulating the quantum dots, increasing the light intensity of red and green light, and significantly improving the color gamut and contrast of the plate, so that the plate can be better used in the field of TV diffuser backplanes and occupy a larger market scale. Second, the Rayleigh scattering layer added to the lower layer can diffuse blue light in daily use, and can play a certain role in preventing blue light and protecting the eyes.

[0021] Third, this method is based on a mature three-layer co-extrusion process, making it easy to mass-produce and cost-effective. The microstructure expands the effective area of ​​the Rayleigh scattering layer, and the light undergoes multiple refractions and scatterings within the microstructure, allowing the Rayleigh scattering layer to more effectively intercept and utilize blue light to excite the quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 : Schematic diagram of the structure of PS quantum dot composite diffusion plate; Figure 2 : Schematic diagram of the principle of PS quantum dot composite diffusion plate. DETAILED DESCRIPTION

[0023] The diffusion masterbatch used in the following examples contains: 9 wt % of an organic silicon diffusion agent, 90 wt % of a base resin PS, and 1 wt % of a processing aid. The organic silicon diffusion agent, model DF20A0-H, was purchased from Changxing and mixed and granulated.

[0024] The red quantum dot masterbatch used in the examples was prepared from CdSe / ZnS red quantum dots (supplied by Hefei Funa, with an excitation peak of 631 nm) and a PS resin matrix. The OD value of the red quantum dot masterbatch was 200 OD / kg (OD is optical density, which represents the quantitative relationship between the concentration of the same detected substance and the absorbed energy at a specific wavelength. In quantum dots, it represents the degree of absorption of blue light). The green quantum dot masterbatch used in the embodiment is green quantum dots with a CdSe core / ZnS shell structure (supplied by Hefei Funa, with an excitation peak of 528 nm) dispersed in a matrix resin PS. The OD value of the green quantum dot masterbatch is 40 OD / kg.

[0025] The PS in the embodiment is general-purpose polystyrene (GPPS).

[0026] The titanium dioxide masterbatch used in the embodiment comprises, by mass percentage, 0.7 wt % of nano titanium dioxide (10-50 nm), 98.3 wt % of base resin PS, and 1 wt % of a processing aid (one of white oil, silicone oil, and naphthenic oil).

[0027] Example 1: A method for preparing a PS quantum dot composite microstructure diffuser plate, comprising the following steps: Upper PS diffusion layer: 95kg PS, 5kg diffusion masterbatch, 0.5kg antioxidant 168, 0.5kg antioxidant 1076; Middle quantum dot layer: 65kg PS, 13kg red quantum dot masterbatch, 22kg green quantum dot masterbatch, 1kg diffusion masterbatch, 0.5kg antioxidant 1010; Lower Rayleigh scattering layer: 97kg PS, 3kg titanium dioxide masterbatch, 0.5kg antioxidant 1010.

[0028] S1. Place the raw materials of the upper, middle and lower layers in a high-speed mixer and stir them at 1000 r / min at 25°C for 5 minutes to ensure that the raw materials are evenly mixed.

[0029] S2. The three mixed raw materials are fed into three extruders at an extrusion temperature of 190-220°C for melt extrusion and compounding is completed in the mold.

[0030] S3. After melt extrusion, the melt is processed in a three-roll calender with an upper roll temperature of 80°C, a middle roll temperature of 120°C, and a microstructured bottom roll (featuring a P150A prismatic microstructure with a prism spacing of 150±10µm, a prism height of 20±5µm, and a diagonal length ≤3mm, with the microstructure facing the outside of the sheet). The bottom roll temperature is 80°C. The line speed is 1.5m / min, and the roller spacing is adjusted to a sheet thickness of 2mm (substrate thickness, excluding microstructure height). The sheet is then shaped at 110-130°C, and the finished sheet is obtained after traction and cutting.

[0031] Example 2: (the lower layer is a Rayleigh scattering layer without microstructure); compared with Example 1, Example 2 differs in that: the surface of the lower Rayleigh scattering layer in Example 1 has no microstructure, and other operations are the same as Example 1.

[0032] A PS quantum dot composite diffuser plate, whose three-layer composite structure includes the following materials in parts by weight: Upper PS diffusion layer: 95kg PS, 5kg diffusion masterbatch, 0.5kg antioxidant 168, 0.5kg antioxidant 1076; Middle quantum dot layer: 65kg PS, 13kg red quantum dot masterbatch, 22kg green quantum dot masterbatch, 1kg diffusion masterbatch, 0.5kg antioxidant 1010; Lower Rayleigh scattering layer: 97kg PS, 3kg titanium dioxide masterbatch, 0.5kg antioxidant 1010.

[0033] A method for preparing a PS quantum dot composite microstructure diffuser plate comprises the following steps: S1. Place the raw materials of the three layers in a high-speed mixer and stir at a speed of 1000 r / min at 25°C for 5 minutes to ensure that the raw materials are evenly mixed.

[0034] S2. The three mixed raw materials are fed into three extruders at an extrusion temperature of 190-220°C for melt extrusion and compounding is completed in the mold.

[0035] S3. After the melt is extruded, it is processed on a three-roll calender with the upper roller temperature at 80°C, the middle roller (mirror roller) temperature at 120°C, and the lower roller (mirror roller) temperature at 80°C. The line speed is 1.5m / min, and the roller spacing is adjusted to achieve a sheet thickness of 2mm. The sheet is then shaped at 110-130°C, and the finished sheet is obtained after pulling and cutting.

[0036] Example 3: Compared with Example 1, Example 3 differs in that there is no diffusion masterbatch in the middle layer, and other operations are the same as Example 1.

[0037] A PS quantum dot composite diffuser plate, whose three-layer composite structure includes the following materials in parts by weight: Upper PS diffusion layer: 95kg PS, 5kg diffusion masterbatch, 0.5kg antioxidant 168, 0.5kg antioxidant 1076; Middle quantum dot layer: 65kg PS, 13kg red quantum dot masterbatch, 22kg green quantum dot masterbatch, 0.5kg antioxidant 1010.

[0038] Lower layer: Rayleigh scattering layer; 97 kg PS, 3 kg titanium dioxide masterbatch, 0.5 kg antioxidant 1010.

[0039] Preparation method: Same as Example 1.

[0040] Comparative Example 1: A method for preparing a conventional blended quantum dot diffuser plate, comprising the following steps: S1, 65kg PS resin, 13kg red quantum dot masterbatch, 22kg green quantum dot masterbatch, 5kg diffusion masterbatch, 0.5kg antioxidant 1076, 0.5kg antioxidant 168, 0.2kg paraffin oil were stirred in a high-speed mixer at 25℃ and 1000r / min for 5 minutes to ensure that the raw materials are evenly mixed.

[0041] S2. The mixed raw materials are fed into an extruder and melt-extruded at an extrusion temperature of 195-215°C.

[0042] S3. The melt is cooled on a cooling roller at 80°C and shaped at 110-130°C, and the finished sheet is obtained after traction and cutting.

[0043] Comparative Example 2: (conventional three-layer quantum dot diffuser plate); a quantum dot diffuser plate was prepared using a three-layer co-extrusion structure, the middle layer was a quantum dot layer, and the upper and lower layers were diffusion layers. The preparation method was the same as in Example 2.

[0044] Upper PS diffusion layer: 95kg PS, 5kg diffusion masterbatch, 0.5kg antioxidant 168, 0.5kg antioxidant 1076; Middle quantum dot layer: 65kg PS, 13kg red quantum dot masterbatch, 22kg green quantum dot masterbatch, 1kg diffusion masterbatch, 0.5kg antioxidant 1010; Lower PS diffusion layer: 95kg PS, 5kg diffusion masterbatch, 0.5kg antioxidant 168, 0.5kg antioxidant 1076.

[0045] Upper layer: PS diffusion layer (same as Example 2) Middle layer: quantum dot layer (same as Example 2) Lower layer: PS diffusion layer (same as upper PS diffusion layer).

[0046] Comparative Example 3: A three-layer quantum dot diffuser plate, the lower layer has a microstructure but no Rayleigh scattering agent.

[0047] Upper PS diffusion layer: 95kg PS, 5kg diffusion masterbatch, 0.5kg antioxidant 168, 0.5kg antioxidant 1076; Middle quantum dot layer: 65kg PS, 13kg red quantum dot masterbatch, 22kg green quantum dot masterbatch, 1kg diffusion masterbatch, 0.5kg antioxidant 1010; Lower PS transparent layer; 100kg PS.

[0048] Upper layer: PS diffusion layer (same as Example 1) Middle layer: quantum dot layer (same as Example 1) Lower layer: PS Transparent layer: pure GPPS, etched microstructure (microstructure type is the same as Example 1) The preparation method is the same as that of Example 1, and the microstructure is formed by the same microstructure roller calendering as that of Example 1.

[0049] Performance test: The performance test was performed on the diffuser plates in the technical solutions of Examples 1-3 and Comparative Examples 1-3: The specific inspection results are shown in Tables 1 and 2 below.

[0050] Light transmittance: The test standard is ASTM D1003. A 2mm light transmittance of ≥40% can meet the requirements for the diffuser. The haze of Examples 1 to 3 can reach about 94%; Flexural modulus and flexural strength: The test standard is ASTM D790.

[0051] Tensile strength: The test standard is ASTM D638.

[0052] Impact strength: The test standard is ASTM D256.

[0053] Excitation red and green light intensity: the test standard is ASTM E903-20

[0054] Table 1 Performance test table:

[0055] Table 2 Comparison of blue light excitation spectrum intensity:

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A PS quantum dot composite diffusion plate, characterized in that: The board consists of a three-layer structure, and the raw materials of each layer are prepared according to the following weight parts: The upper layer is the PS diffusion layer: 90-100 parts of PS resin, 2-10 parts of diffusion masterbatch, and 0.1-1 parts of additives; The middle layer is the quantum dot layer: 50-100 parts of PS resin, 6-40 parts of quantum dot masterbatch, 0.1-10 parts of diffusion masterbatch, and 0.1-1 parts of additives; the quantum dot masterbatch includes red quantum dot masterbatch and green quantum dot masterbatch; The lower layer is the Rayleigh scattering layer; 95-100 parts of PS resin, 1-5 parts of nano titanium dioxide masterbatch, and 0.1-1 part of additives.

2. The PS quantum dot composite diffusion plate according to claim 1, characterized in that: The quantum dots contained in the quantum dot masterbatch are selected from one or more of CdSe-based quantum dots, CdTe-based quantum dots, PbS-based quantum dots, perovskite quantum dots, and carbon-based quantum dots.

3. The PS quantum dot composite diffusion plate according to claim 1, characterized in that: The quantum dot masterbatch includes 3 to 15 parts of red quantum dot masterbatch and 3 to 25 parts of green quantum dot masterbatch.

4. The PS quantum dot composite diffusion plate according to claim 1, characterized in that: The mass content of the nano-titanium dioxide in the nano-titanium dioxide masterbatch is 0.5-2%; the particle size of the nano-titanium dioxide is 10-50 nm.

5. The PS quantum dot composite diffusion plate according to claim 1, characterized in that: The auxiliary agent includes one or more of paraffin oil, naphthenic oil, silicone oil, antioxidant 1076, antioxidant 1010, ethylene-vinyl acetate copolymer grafted with maleic anhydride, butyl acrylate grafted with maleic anhydride, methyl methacrylate and glycidyl methacrylate copolymer, acrylonitrile-butadiene-styrene plastic grafted with maleic anhydride, glycidyl methacrylate grafted with polystyrene, and polystyrene grafted with maleic anhydride copolymer.

6. The PS quantum dot composite diffusion plate according to claim 1, characterized in that: A microstructure is formed on the surface of the underlying Rayleigh scattering layer.

7. The PS quantum dot composite diffusion plate according to claim 5, characterized in that: The microstructure is a tooth-like microstructure, and its cross-sectional shape is one or more of a triangle, a quadrilateral, a pentagon, and a hexagon.

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