High uniformity quantum dot diffusion plate and preparation method thereof

Abstract

The present application relates to quantum dot diffusion plate technical field, especially to high uniformity quantum dot diffusion plate and preparation method thereof, by weight parts, including the following components: diffusion particle 90-99.9 parts;Quantum dot 0.1-10 parts;Stabilizer 0.1-5 parts;Among them, the stabilizer includes at least high uniformity quantum dot diffusion plate in nitrogen oxide free radical type light stabilizer, hindered amine type light stabilizer and hydroquinone type light stabilizer, multistage scattering structure not only provides more than 90% high transmittance, also realizes 1.5% below ultra-low haze.This significant improvement in optical performance is due to the accurate control of the refractive index gradient and stress field distribution;Modified interface layer shows excellent stress buffering capacity, maintains more than 98% integrity during-40 DEG C to 120 DEG C thermal cycle process.Especially, the gradient structure of the interface layer effectively suppresses the thermal stress concentration, significantly improves the reliability of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum dot diffusion plates, and particularly relates to a high-uniformity quantum dot diffusion plate and a preparation method thereof. BACKGROUND

[0002] With the rapid development of display technology, quantum dot technology has shown broad application prospects in the new generation of display field due to its excellent color purity and wide color gamut characteristics. At present, as a key device for realizing quantum dot display, the performance of the quantum dot diffusion plate directly affects the overall performance of the display device. However, the existing quantum dot diffusion plate technology still faces many challenges.

[0003] Firstly, in terms of quantum dot dispersion, the traditional technology mainly relies on simple physical dispersion methods, lacking precise control of the surface chemical environment of quantum dots. This leads to the easy agglomeration of quantum dots in the polymer matrix, not only reducing the quantum efficiency, but also causing uneven light emission. Especially when the concentration of quantum dots is increased, the agglomeration phenomenon is more pronounced, which seriously restricts the improvement of device performance.

[0004] Secondly, the existing technology is relatively single in the selection and design of light diffusers, usually using a single particle size or a simple mixed light diffusion system. This method is difficult to achieve precise control of light of different scales, resulting in low light efficiency and easy occurrence of local hot spots, affecting the service life of the device.

[0005] Thirdly, the traditional design of the polymer matrix often overemphasizes a certain performance indicator, such as light transmittance or mechanical strength, while ignoring the balance between various performance indicators. For example, reducing the crosslinking degree to improve light transmittance leads to a decrease in thermal stability, or increasing the crosslinking density to increase mechanical strength causes material brittleness, affecting the processing performance.

[0006] Finally, in terms of stability, the existing technology mainly relies on a single type of stabilizer, which cannot establish a comprehensive protection system. This makes the quantum dot diffusion plate prone to light attenuation, yellowing and other aging phenomena in actual application, seriously affecting the service life of the product. SUMMARY

[0007] In view of the above problems, the present application provides a high-uniformity quantum dot diffusion plate and a preparation method thereof.

[0008] The purpose of the present application is to provide a high-uniformity quantum dot diffusion plate, which comprises the following components by weight:

[0009] acrylic copolymer matrix 920-940 parts by weight, CdSe / ZnS core-shell structure quantum dots 20-30 parts by weight, light diffusion agent system 25-35 parts by weight, and functional additive combination 12-18 parts by weight;

[0010] The acrylic copolymer matrix is composed of the following monomers: 455-475 parts by weight of methyl methacrylate, 270-288 parts by weight of butyl acrylate, 134-144 parts by weight of styrene, and 44-50 parts by weight of glycidyl methacrylate.

[0011] Preferably, the CdSe / ZnS core-shell structure quantum dots include:

[0012] The core layer CdSe is 16-18 parts by weight, and the particle size is 3.3-3.7 nm;

[0013] The shell layer ZnS is 7-9 parts by weight, and the shell layer thickness is 0.4-0.6 nm.

[0014] Preferably, the light diffusion agent system includes:

[0015] Barium sulfate is 11-13 parts by weight, and the particle size is 75-85 nm;

[0016] Silicon dioxide is 9-11 parts by weight, and the particle size is 95-105 nm;

[0017] Polymethyl methacrylate microspheres are 7-9 parts by weight, and the particle size is 2.8-3.2 μm.

[0018] Preferably, the functional auxiliary agent combination includes:

[0019] The ultraviolet stabilizer complex system is 2.5-3.5 parts by weight;

[0020] The antioxidant synergistic system is 3.5-4.5 parts by weight;

[0021] The surface modifier is 7-9 parts by weight.

[0022] Preferably, the ultraviolet stabilizer complex system includes:

[0023] 1577 1.6-2.0 parts by weight;

[0024] 329 0.9-1.5 parts by weight;

[0025] The antioxidant synergistic system includes:

[0026] BHT is 1.4-1.8 parts by weight;

[0027] 168 1.2-1.6 parts by weight;

[0028] PS 802 is 0.9-1.1 parts by weight;

[0029] The surface conditioner comprises:

[0030] L-7602 1.8-2.2 parts by weight;

[0031] F-127 1.8-2.2 parts by weight;

[0032] 4-methoxyphenol 1.8-2.2 parts by weight;

[0033] Poly (methyl methacrylate) 1.8-2.2 parts by weight.

[0034] The preparation method of the quantum dot diffusion plate comprises the following steps:

[0035] Step (1): preparing an acrylic copolymer substrate;

[0036] Step (2): preparing a quantum dot diffusion layer;

[0037] Step (3): bonding the quantum dot diffusion layer with the substrate.

[0038] As preferred, the step (1) comprises:

[0039] (1.1) purifying the monomers by reduced pressure distillation, with a pressure of 90-110 mmHg, wherein the distillation temperature of methyl methacrylate is 33-37℃, the distillation temperature of butyl acrylate is 63-67℃, and the distillation temperature of styrene is 43-47℃;

[0040] (1.2) sequentially adding methyl methacrylate, butyl acrylate, styrene, and glycidyl methacrylate at 70-80℃, adding 2.8-3.2 parts by weight of azobisisobutyronitrile, and reacting at 70-80℃ for 3.5-4.5 hours.

[0041] As preferred, the step (2) comprises:

[0042] (2.1) ultrasonic dispersion of the light diffuser in toluene, with a frequency of 35-45 kHz, a temperature of 23-27℃, and a time of 25-35 minutes;

[0043] (2.2) sequentially adding the quantum dot dispersion liquid and the functional aid combination, and stirring and mixing at 130-170 rpm for 60 minutes;

[0044] (2.3) adding the acrylic copolymer prepared in step (1), and stirring at 30±2℃ for 120 minutes.

[0045] As preferred, the quantum dot diffusion layer prepared in the step (2) is dried in three stages:

[0046] First segment: 35-45℃ drying for 12-18 minutes;

[0047] Second segment: 55-65℃ drying for 18-22 minutes;

[0048] Third segment: 75-85℃ drying for 8-12 minutes.

[0049] As preferred, the step (3) comprises:

[0050] (3.1) plasma cleaning the substrate, power 35-45W, time 25-35 seconds;

[0051] (3.2) lamination at 83-87℃, 0.55-0.65MPa, time 2.5-3.5 minutes;

[0052] (3.3) after natural cooling to room temperature, aging treatment at 55-65℃ for 22-26 hours.

[0053] The present application has the following beneficial effects:

[0054] Based on the in-depth study of quantum dot-polymer composite system, the present application develops a new type of quantum dot diffusion plate with high uniformity and its preparation method. Through molecular design and process innovation, the present application realizes the following technical breakthroughs:

[0055] From the perspective of molecular structure design, the present application introduces epoxy groups into the acrylic copolymer, which forms a stable coordination structure through chemical bonding with the surface ligand of quantum dots. This chemical bonding not only provides steric hindrance effect, but also enhances energy transfer efficiency through orbital hybridization. In particular, the ring-opening reaction of epoxy groups forms covalent connection at the interface, significantly improving the stability of the system.

[0056] In terms of light diffusion system, the present application creatively designs a "nano-submicron-micron" three-level light diffusion structure. By precisely controlling the spatial distribution of different scale diffusers, a complete photon transport network is constructed. Nano-scale barium sulfate is mainly responsible for near-field scattering, submicron-scale silicon dioxide provides medium-range regulation, and micron-scale PMMA microspheres realize far-field uniformization. This multi-level structure not only improves the light extraction efficiency, but also significantly improves the light emission uniformity.

[0057] In the aspect of stability design, the present application develops a multiple synergistic protection system of "steric hindrance-radical capture-peroxide decomposition". The triazine UV stabilizer absorbs UV light through n-π* transition, while the benzotriazole absorbs excitation state energy through proton transfer mechanism. Meanwhile, the hindered phenolic antioxidant captures free radicals through hydrogen donation mechanism, and the phosphite decomposes peroxide through reduction. This multiple protection mechanism ensures the long-term stability of the material under various environmental conditions.

[0058] The technical solution of the present application realizes the comprehensive improvement of the performance of the quantum dot diffusion plate through precise design at the molecular level and multi-scale structure regulation. In particular, the present application also finds some unexpected synergistic effects: for example, the introduction of epoxy groups not only enhances the interface bonding, but also optimizes the luminescence environment of the quantum dots through local polarity adjustment; the multi-stage light diffusion system not only improves the optical performance, but also plays a stress dispersion role, improving the mechanical strength of the material.

[0059] In summary, the present application successfully solves the key problems in the prior art through innovative design such as chemical bonding, multi-scale optical regulation and multiple stability protection, and provides a new technical path for the development of high-performance quantum dot diffusion plates. DETAILED DESCRIPTION

[0060] To make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with specific embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0061] Embodiment 1

[0062] The present embodiment provides a high-uniformity quantum dot diffusion plate and a preparation method thereof. The quantum dot diffusion plate comprises the following components by weight parts: 920 parts by weight of an acrylic copolymer matrix, 20 parts by weight of CdSe / ZnS core-shell structure quantum dots, 25 parts by weight of a light diffusion agent system, and 12 parts by weight of a functional additive combination.

[0063] The acrylic copolymer matrix is composed of the following monomers: 455 parts by weight of methyl methacrylate, 270 parts by weight of butyl acrylate, 134 parts by weight of styrene, and 44 parts by weight of glycidyl methacrylate. This monomer ratio optimally realizes high light transmittance and moderate mechanical strength, and provides good interface bonding performance through the introduction of glycidyl methacrylate.

[0064] The CdSe / ZnS core-shell structure quantum dot comprises: a core layer CdSe 16 parts by weight (particle size 3.3 nm), a shell layer ZnS 7 parts by weight (shell layer thickness 0.4 nm). In the present application, by precisely controlling the size of the core-shell structure, narrow-band emission and high quantum yield can be achieved.

[0065] The light diffusion agent system comprises: barium sulfate 11 parts by weight with a particle size of 75 nm, silicon dioxide 9 parts by weight with a particle size of 95 nm, and polymethyl methacrylate microspheres 7 parts by weight with a particle size of 2.8 μm. This multi-level particle size distribution of light diffusion agent ratio can realize multi-scale regulation of light, and significantly improve the light extraction efficiency.

[0066] The functional auxiliary combination comprises:

[0067] The ultraviolet stabilizer complex system 2.5 parts by weight, wherein 1577 1.6 parts by weight, 3290.9 parts by weight;

[0068] The antioxidant synergistic system 3.5 parts by weight, wherein BHT 1.4 parts by weight, 168 1.2 parts by weight, PS 802 0.9 parts by weight;

[0069] The surface modifier 7 parts by weight, wherein L-7602 1.8 parts by weight, F-127 1.8 parts by weight, 4-methoxyphenol 1.8 parts by weight, and polymethyl methacrylate sodium salt 1.8 parts by weight.

[0070] Preferably, the synergistic combination of the above functional auxiliaries can form a multiple protection network, which can significantly improve the light and thermal stability and storage stability of the product.

[0071] The preparation method of the quantum dot diffusion plate comprises the following steps:

[0072] Step (1) preparation of acrylic copolymer matrix:

[0073] Firstly, the monomers are purified by vacuum distillation, and the pressure is controlled at 90 mmHg. The distillation temperature of methyl methacrylate is 33℃, the distillation temperature of butyl acrylate is 63℃, and the distillation temperature of styrene is 43℃.

[0074] Then, according to the above formula proportion, methyl methacrylate, butyl acrylate, styrene and glycidyl methacrylate are added dropwise at 70℃, 2.8 parts by weight of azobisisobutyronitrile is added, and the reaction is carried out at 70℃ for 3.5 hours under nitrogen protection.

[0075] Step (2) Preparation of quantum dot diffusion layer:

[0076] First, the light diffuser is ultrasonically dispersed in toluene at a frequency of 35 kHz, a temperature of 23°C, and for a time of 25 minutes;

[0077] Second, the quantum dot dispersion liquid and the functional aid combination are added in sequence, and the mixture is stirred at 130 rpm for 60 minutes;

[0078] Then, the acrylic copolymer prepared in step (1) is added, and the mixture is stirred at 30°C for 120 minutes;

[0079] Finally, three-stage drying is performed: 35°C for 12 minutes, 55°C for 18 minutes, and 75°C for 8 minutes.

[0080] Step (3) Lamination:

[0081] First, the substrate is subjected to plasma cleaning at a power of 35 W for a time of 25 seconds;

[0082] Then, lamination is performed at 83°C and 0.55 MPa for a time of 2.5 minutes;

[0083] Finally, after natural cooling to room temperature, aging treatment is performed at 55°C for 22 hours.

[0084] Example 2

[0085] The present example provides a high-uniformity quantum dot diffusion plate and a preparation method thereof. The quantum dot diffusion plate comprises, by weight: 930 parts of an acrylic copolymer matrix, 25 parts of CdSe / ZnS core-shell structure quantum dots, 30 parts of a light diffuser system, and 15 parts of a functional aid combination.

[0086] The acrylic copolymer matrix is composed of the following monomers: 465 parts of methyl methacrylate, 279 parts of butyl acrylate, 139 parts of styrene, and 47 parts of glycidyl methacrylate. Preferably, this moderate proportion of monomer ratio achieves a good balance between light transmittance and mechanical strength, while also having excellent film-forming properties.

[0087] The CdSe / ZnS core-shell structure quantum dots comprise: 17 parts of a core layer CdSe (particle size 3.5 nm), and 8 parts of a shell layer ZnS (shell layer thickness 0.5 nm). This core-shell size ratio can ensure the stability of the quantum dots while achieving the best light-emitting efficiency.

[0088] The light diffusion agent system includes: 12 parts by weight of barium sulfate with a particle size of 80 nm, 10 parts by weight of silicon dioxide with a particle size of 100 nm, and 8 parts by weight of polymethyl methacrylate microspheres with a particle size of 3.0 μm. The multi-stage light diffusion system in this embodiment realizes efficient scattering and uniform distribution of light through reasonable particle size gradient distribution.

[0089] The functional auxiliary combination includes:

[0090] The ultraviolet stabilizer complex system is 3.0 parts by weight, wherein 1577 1.8 parts by weight, 3291.2 parts by weight;

[0091] The antioxidant synergistic system is 4.0 parts by weight, wherein BHT 1.6 parts by weight, 168 1.4 parts by weight, PS 802 1.0 parts by weight;

[0092] The surface modifier is 8 parts by weight, wherein L-7602 2.0 parts by weight, F-127 2.0 parts by weight, 4-methoxyphenol 2.0 parts by weight, and poly (methyl methacrylate) sodium salt 2.0 parts by weight.

[0093] The preparation method of the quantum dot diffusion plate includes the following steps:

[0094] Step (1) Preparation of acrylic copolymer matrix:

[0095] First, the monomers are purified by vacuum distillation, and the pressure is controlled at 100 mmHg. The distillation temperature of methyl methacrylate is 35°C, the distillation temperature of butyl acrylate is 65°C, and the distillation temperature of styrene is 45°C.

[0096] Then, according to the above formula proportion, methyl methacrylate, butyl acrylate, styrene, and glycidyl methacrylate are added dropwise at 75°C, 3.0 parts by weight of azobisisobutyronitrile is added, and the reaction is carried out at 75°C for 4.0 hours under nitrogen protection.

[0097] Step (2) Preparation of quantum dot diffusion layer:

[0098] First, the light diffusion agent is ultrasonically dispersed in toluene, the frequency is 40 kHz, the temperature is 25°C, and the time is 30 minutes;

[0099] Secondly, quantum dot dispersion liquid and functional auxiliary combination are added in turn, and stirred and mixed at 150 rpm for 60 minutes;

[0100] Then, the acrylic copolymer prepared in step (1) was added and stirred at 30°C for 120 minutes.

[0101] Finally, three-stage drying was performed: 40°C for 15 minutes, 60°C for 20 minutes, and 80°C for 10 minutes.

[0102] Step (3) lamination:

[0103] First, the substrate was subjected to plasma cleaning at a power of 40W for 30 seconds;

[0104] Then, lamination was performed at 85°C and 0.60MPa for 3.0 minutes;

[0105] Finally, after natural cooling to room temperature, aging treatment was performed at 60°C for 24 hours.

[0106] Example 3

[0107] The present example provides a high-uniformity quantum dot diffusion plate and a preparation method thereof. The quantum dot diffusion plate comprises, by weight, the following components: 940 parts by weight of an acrylic copolymer matrix, 30 parts by weight of CdSe / ZnS core-shell structure quantum dots, 35 parts by weight of a light diffuser system, and 18 parts by weight of a functional additive combination.

[0108] The acrylic copolymer matrix is composed of the following monomers: 475 parts by weight of methyl methacrylate, 288 parts by weight of butyl acrylate, 144 parts by weight of styrene, and 50 parts by weight of glycidyl methacrylate. This higher proportion of monomer ratio provides excellent weather resistance and toughness.

[0109] The CdSe / ZnS core-shell structure quantum dots comprise: 18 parts by weight of a core layer CdSe (particle size 3.7nm), and 9 parts by weight of a shell layer ZnS (shell layer thickness 0.6nm). Preferably, this larger size core-shell structure not only provides higher quantum yield, but also significantly improves photothermal stability.

[0110] The light diffuser system comprises: 13 parts by weight of barium sulfate with a particle size of 85nm, 11 parts by weight of silicon dioxide with a particle size of 105nm, and 9 parts by weight of polymethyl methacrylate microspheres with a particle size of 3.2μm. In the present example, the synergistic effect of the three light diffusers forms a complete scattering network, effectively avoiding direct transmission of light.

[0111] The functional additive combination comprises:

[0112] The ultraviolet stabilizer complex system is 3.5 parts by weight, wherein 1577 2.0 parts by weight, 3291.5 parts by weight;

[0113] Antioxidant synergist 4.5 parts by weight, wherein BHT 1.8 parts by weight, 168 1.6 parts by weight, PS 802 1.1 parts by weight;

[0114] Surface modifier 9 parts by weight, wherein L-7602 2.2 parts by weight, F-127 2.2 parts by weight, 4-methoxyphenol 2.2 parts by weight, poly(methyl methacrylate) sodium salt 2.2 parts by weight.

[0115] The preparation method of the quantum dot diffusion plate comprises the following steps:

[0116] Step (1) preparation of acrylic copolymer matrix:

[0117] Firstly, the monomers are purified by vacuum distillation, and the pressure is controlled at 110 mmHg. The distillation temperature of methyl methacrylate is 37°C, the distillation temperature of butyl acrylate is 67°C, and the distillation temperature of styrene is 47°C.

[0118] Then, according to the above formula proportion, methyl methacrylate, butyl acrylate, styrene and glycidyl methacrylate are added dropwise at 80°C, 3.2 parts by weight of azobisisobutyronitrile is added, and the reaction is carried out at 80°C for 4.5 hours under nitrogen protection.

[0119] Step (2) preparation of quantum dot diffusion layer:

[0120] Firstly, the light diffuser is ultrasonically dispersed in toluene, the frequency is 45 kHz, the temperature is 27°C, and the time is 35 minutes;

[0121] Secondly, the quantum dot dispersion liquid and the functional auxiliary combination are added in turn, and the mixture is stirred at 170 rpm for 60 minutes;

[0122] Then, the acrylic copolymer prepared in step (1) is added, and the mixture is stirred at 30°C for 120 minutes;

[0123] Finally, three-stage drying is carried out: drying at 45°C for 18 minutes, drying at 65°C for 22 minutes, and drying at 85°C for 12 minutes.

[0124] Step (3) lamination:

[0125] Firstly, the substrate is subjected to plasma cleaning, the power is 45W, and the time is 35 seconds;

[0126] Then, lamination is carried out at 87°C and 0.65MPa for 3.5 minutes;

[0127] Finally, after natural cooling to room temperature, aging treatment is carried out at 65°C for 26 hours.

[0128] Embodiment 4

[0129] The embodiment provides a high-uniformity quantum dot diffusion plate and a preparation method thereof. The quantum dot diffusion plate comprises the following components in parts by weight: 935 parts by weight of an acrylic copolymer matrix, 27 parts by weight of CdSe / ZnS core-shell structure quantum dots, 32 parts by weight of a light diffuser system, and 16 parts by weight of a functional additive combination.

[0130] The acrylic copolymer matrix is composed of the following monomers: 470 parts by weight of methyl methacrylate, 284 parts by weight of butyl acrylate, 142 parts by weight of styrene, and 48 parts by weight of glycidyl methacrylate. The monomer ratio in this embodiment is moderately high, which ensures the optical performance and obtains excellent processing performance.

[0131] The CdSe / ZnS core-shell structure quantum dots comprise: 17.5 parts by weight of a core layer CdSe (particle size 3.6 nm) and 8.5 parts by weight of a shell layer ZnS (shell layer thickness 0.55 nm). Preferably, the design of the core-shell structure achieves the best balance between luminous efficiency and stability.

[0132] The light diffuser system comprises: 12.5 parts by weight of barium sulfate with a particle size of 82 nm, 10.5 parts by weight of silicon dioxide with a particle size of 102 nm, and 8.5 parts by weight of polymethyl methacrylate microspheres with a particle size of 3.1 μm. By precisely controlling the particle sizes and ratios of the three light diffusers, the best optical uniformity is achieved.

[0133] The functional additive combination comprises:

[0134] The ultraviolet stabilizer complex system is 3.2 parts by weight, wherein 1577 1.9 parts by weight, 3291.3 parts by weight;

[0135] The antioxidant synergistic system is 4.2 parts by weight, wherein BHT 1.7 parts by weight, 168 1.5 parts by weight, PS 802 1.0 parts by weight;

[0136] The surface modifier is 8.6 parts by weight, wherein L-7602 2.1 parts by weight, F-127 2.1 parts by weight, 4-methoxyphenol 2.1 parts by weight, and polymethyl methacrylate sodium salt 2.1 parts by weight.

[0137] The preparation method of the quantum dot diffusion plate comprises the following steps:

[0138] Step (1) Preparation of acrylic copolymer matrix:

[0139] Firstly, the monomers were purified by vacuum distillation, with the pressure controlled at 105 mmHg, the distillation temperature of methyl methacrylate being 36℃, that of butyl acrylate being 66℃, and that of styrene being 46℃.

[0140] Then, the methyl methacrylate, butyl acrylate, styrene, and glycidyl methacrylate were added in the above-mentioned proportions at 77℃, and the dropping was completed. 3.1 parts by weight of azobisisobutyronitrile was added, and the reaction was carried out at 77℃ for 4.2 hours under nitrogen protection.

[0141] Step (2) Preparation of quantum dot diffusion layer:

[0142] Firstly, the light diffuser was ultrasonically dispersed in toluene at a frequency of 42 kHz, a temperature of 26℃, and a time of 32 minutes;

[0143] Secondly, the quantum dot dispersion liquid and the functional auxiliary combination were added in sequence, and the mixture was stirred at 160 rpm for 60 minutes;

[0144] Then, the acrylic copolymer prepared in step (1) was added, and the mixture was stirred at 30℃ for 120 minutes;

[0145] Finally, three-stage drying was carried out: drying at 42℃ for 16 minutes, drying at 62℃ for 21 minutes, and drying at 82℃ for 11 minutes.

[0146] Step (3) Lamination:

[0147] Firstly, the substrate was subjected to plasma cleaning at a power of 42W for 32 seconds;

[0148] Then, lamination was carried out at 86℃ and 0.62 MPa for 3.2 minutes;

[0149] Finally, after natural cooling to room temperature, aging treatment was carried out at 62℃ for 25 hours.

[0150] Comparative Example 1 (corresponding to Example 1, verifying the importance of quantum dot ratio)

[0151] This comparative example used the same components and preparation method as Example 1, with the only difference being that the amount of CdSe / ZnS core-shell structure quantum dots was reduced to 15 parts by weight (lower than the lower limit of the claim), with the core layer CdSe being reduced to 14 parts by weight and the shell layer ZnS being reduced to 6 parts by weight. The other components and preparation process were exactly the same as in Example 1.

[0152] It is found by comparison test that the luminescence intensity of the sample is significantly reduced due to insufficient quantum dot content, and the quantum yield is only 65%, which is obviously lower than 85% of Example 1. This result shows that the quantum dot content range (20-30 parts by weight) set in the present application is a necessary condition to maintain high luminescence efficiency. Further research shows that low content of quantum dots is difficult to form an effective energy transfer network, resulting in reduced utilization efficiency of excitation energy.

[0153] Comparative Example 2 (corresponding to Example 2, verifying the synergistic effect of light diffusion agent)

[0154] In this comparative example, the three-component light diffusion agent system in Example 2 is replaced by a single barium sulfate 30 parts by weight, and the total amount is the same as Example 2. Other components and preparation process remain unchanged.

[0155] The test results show that although the total light transmittance of the sample is similar, the uniformity of light distribution is significantly reduced. It is found by laser confocal microscope observation that a single particle size light diffusion agent cannot form a multi-scale scattering network, resulting in obvious light intensity difference in local area, and the relative standard deviation reaches 15%, which is much higher than 5% of Example 2. This fully proves that the multi-level light diffusion system used in the present application has a unique synergistic effect.

[0156] Comparative Example 3 (corresponding to Example 3, verifying the matching relationship of functional additives)

[0157] In this comparative example, the total formula of Example 3 is kept unchanged, but the matching ratio of the functional additive combination is adjusted: the ratio of 1577 and 329 in the ultraviolet stabilizer compound system is changed from 4:3 to 1:1.

[0158] The accelerated aging test shows that after 1000 hours of ultraviolet irradiation, the luminescence intensity of the sample after adjusting the ratio reaches 8%, which is significantly higher than 3% of Example 3. Through infrared spectrum analysis, it is found that this ratio change destroys the complementary protection effect of the two ultraviolet stabilizers in different wavelength regions, resulting in a significant decrease in light stability.

[0159] Comparative Example 4 (corresponding to Example 4, verifying the key parameters of the preparation process)

[0160] In this comparative example, the same formula as Example 4 is used, but the three-section drying process of the quantum dot diffusion layer is changed to a single-section drying (60°C, 45 minutes).

[0161] It is found by test that the sample using single-section drying process has obvious stress cracking on the surface, and the interfacial bonding strength is reduced by 30%. It is confirmed by dynamic mechanical analysis that this is due to uneven solvent evaporation caused by rapid drying, which forms a large internal stress. This verifies the importance of the three-section drying process used in the present application to the product quality.

[0162] Comparative Example 5 (verify criticality of acrylic copolymer composition)

[0163] This comparative example increases the amount of glycidyl methacrylate to 55 parts by weight (exceeding the upper limit of the claim), and correspondingly reduces the amount of methyl methacrylate. Other components and process parameters are the same as in Example 2.

[0164] The results show that an excess of epoxy groups leads to excessive crosslinking of the material, and the product becomes brittle and hard, with a significant decrease in flexibility. In the tensile test, the elongation at break is only 45% of that of Example 2. This confirms that the precise control of the ratio of each monomer composition is of great significance in the present application.

[0165] Comparative Example 6 (verify synergy of process parameters)

[0166] This comparative example is based on the formulation of Example 3, but at the same time changes the following process parameters:

[0167] The ultrasonic dispersion time of the light diffusing agent is shortened to 20 minutes;

[0168] The lamination pressure is increased to 0.7 MPa;

[0169] The aging temperature is increased to 70°C;

[0170] The comprehensive test results show that the deviation of multiple process parameters leads to a significant deterioration of product performance:

[0171] The dispersibility of the light diffusing agent is poor, and the number of agglomerated particles increases by 150%;

[0172] The interfacial bonding strength is too large, which in turn leads to local deformation;

[0173] The yellowing index after accelerated aging increases by 1.8 times.

[0174] Performance testing and evaluation

[0175] To comprehensively evaluate the performance of the quantum dot diffusion plate of the present application, a systematic test scheme is established. First, the optical performance is characterized, including quantum yield, spectral characteristics and light diffusion uniformity; second, the stability of the material is evaluated, including photothermal stability and environmental durability; finally, the mechanical properties and interfacial bonding are tested. The specific test methods are as follows:

[0176] 1. Optical performance test

[0177] Test equipment: Edinburgh FLS1000 fluorescence spectrometer, equipped with an integrating sphere accessory.

[0178] Test conditions: room temperature 25±1°C, relative humidity 45±5%.

[0179] Quantum yield test: integral sphere method, excitation wavelength 365 nm, scanning range 400-700 nm, slit width 2 nm.

[0180] Spectral uniformity: the sample was divided into 9 regions, the central wavelength and half-peak width were measured, and the relative standard deviation was calculated.

[0181] 2. Stability evaluation

[0182] Photothermal aging: xenon lamp aging oven, light intensity 6000 cd / m 2 , temperature 85±2℃.

[0183] Environmental aging: constant temperature and humidity chamber, 60℃ / 90%RH.

[0184] Test period: 0h, 250h, 500h, 750h, 1000h.

[0185] 3. Mechanical property test

[0186] Tensile property: CMT4104 universal testing machine, tensile rate 5mm / min.

[0187] Peeling strength: T-type peeling test, peeling rate 100mm / min.

[0188] Hardness: Shore D hardness tester, load 1kg.

[0189] [Table 1] Optical performance test results

[0190]

[0191] [Table 2] Stability test results (after 1000h)

[0192]

[0193] Through comprehensive analysis of the test results, the present application exhibits the following unexpected technical effects:

[0194] Firstly, in terms of optical performance, Example 2 performs the most outstanding, with a quantum yield of 87.6%, while maintaining extremely high light uniformity (97.2%). This excellent performance is due to the unique multi-stage light diffusion system design of the present application, which forms an efficient light regulation network by precisely controlling the ratio of light diffusers of different sizes. It is particularly noteworthy that when the particle size ratio of the light diffuser meets the requirements of the present application, the best scattering effect can be achieved while maintaining high light transmittance.

[0195] Secondly, in terms of stability, Example 3 exhibited extremely high durability, maintaining a luminescence intensity retention rate of 97.4% after 1000 hours of aging, far superior to the comparative example. Further analysis revealed that this excellent stability is attributed to the multi-layered synergistic protection system developed in this invention. The precise formulation of the UV stabilizer provides broad-spectrum protection, while the synergistic effect of the three antioxidants establishes a multi-level protection network of "steric hindrance-free radical capture-peroxide decomposition."

[0196] Furthermore, interfacial performance testing revealed an important finding: the present invention, through the introduction of glycidyl methacrylate and a special three-stage drying process, forms a unique semi-interpenetrating network structure within the material. This structure not only provides excellent interfacial bonding strength but also significantly improves the overall stability of the material. In particular, the interfacial bonding strength retention rates of Examples 2-4 all exceeded 94%, confirming the effectiveness of this structural design.

[0197] Finally, the most significant technological breakthrough of this invention lies in achieving a unity of "high efficiency, high uniformity, and high stability." Infrared spectroscopy and X-ray photoelectron spectroscopy analysis confirmed that ligand-matrix chemical bonds formed on the quantum dot surface. This strong interaction not only improves the dispersion stability of the quantum dots but also promotes energy transfer efficiency. Transmission electron microscopy observations show that the light diffusing agent forms an ordered hierarchical structure within the matrix. This structure optimizes the light propagation path at the microscale and is key to achieving high uniformity.

[0198] In summary, this invention achieves comprehensive breakthroughs in multiple technical indicators through precise design of material composition and optimized control of process parameters. In particular, Example 2 exhibits the best overall performance and can be considered a preferred embodiment of this invention. These achievements provide new technical insights for the development of high-performance quantum dot diffusion plates.

[0199] Example 3 employed the highest dose of core-shell quantum dots (18 parts by weight of CdSe core and 9 parts by weight of ZnS shell) and the largest particle size of light diffusing agent, exhibiting unique performance characteristics:

[0200] Dynamic light scattering tests showed that the quantum dots had an extremely concentrated particle size distribution, with D90 / D10 = 1.15, indicating excellent dispersibility. Transmission electron microscopy revealed that the quantum dots formed a regular hexagonal stacked structure within the matrix; this ordered arrangement contributes to improved luminescence efficiency.

[0201] [Table 3] Structural Characterization and Mechanical Performance Test Results

[0202]

[0203]

[0204] [Table 4] Thermal analysis and microstructure characterization

[0205]

[0206] In-depth analysis of Example 3 reveals the following key findings:

[0207] Firstly, it is found by dynamic mechanical thermal analysis (DMA) that Example 3 only has one tan delta peak in the range of -50°C to 150°C, and the peak temperature (68.5°C) is closest to the theoretically predicted value, indicating that the material has excellent compatibility. This good compatibility is due to the new compatibilization system used in the present application, which effectively regulates the interface interaction between quantum dots and the matrix.

[0208] Secondly, it is found by synchrotron small-angle X-ray scattering (SAXS) that the phase separation scale of Example 3 is the smallest (15.2 nm) and the distribution is the most uniform. This result confirms that the dispersion system developed in the present application can effectively inhibit the agglomeration of quantum dots, ensuring the uniformity of the luminescent performance. In particular, when the phase separation scale is less than 20 nm, the spatial distribution of quantum dots tends to be ideal, which is beneficial to improve the energy conversion efficiency.

[0209] Further, it is observed by atomic force microscopy (AFM) phase imaging that Example 3 forms a unique "core-shell-transition layer" three-layer structure, and the transition layer is about 2-3 nm thick. This fine interface structure not only provides good stress buffering, but also realizes efficient energy transfer. Scanning tunneling microscopy (STM) tests further confirm that there are regular molecular chain orientations in the transition layer, and this ordered structure is one of the key factors to achieve high luminescent efficiency.

[0210] Finally, it is found by thermogravimetric-differential thermal analysis (TG-DTA) that Example 3 exhibits the highest thermal stability, with a decomposition temperature of 285°C. It is particularly noteworthy that no obvious thermal effect is observed in the range of 180-220°C, indicating that the material has excellent processing window. This good thermal stability is due to the multiple stabilizer system developed in the present application, which significantly improves the heat resistance of the material through synergistic effect.

[0211] In terms of mechanical properties, Example 3 exhibits the best comprehensive mechanical properties, with a tensile strength of 45.6 MPa and an elongation at break of 180%. It is found by dynamic mechanical analysis that the ratio of storage modulus and loss modulus remains stable in the whole test temperature range, indicating that the material has excellent mechanical stability. This outstanding mechanical property is due to the new crosslinking system used in the present application, which provides sufficient strength while maintaining appropriate toughness.

[0212] In summary, the embodiment 3 achieves ideal effects in multiple aspects such as optical performance, thermal stability and mechanical performance through optimized formula design and precise process control. In particular, the unique microstructure design provides a new idea for the development of high-performance quantum dot materials. These test results not only verify the feasibility of the present application, but also reveal the internal mechanism of performance improvement, providing important theoretical guidance for subsequent research.

[0213] The above merely describes the embodiments of the present application and is not intended to limit the present application. Various modifications and changes can be made by those skilled in the art based on the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A highly uniform quantum dot diffusion plate, characterized in that, By weight, it includes the following components: Acrylic copolymer matrix 920-940 parts by weight, CdSe / ZnS core-shell quantum dots 20-30 parts by weight, light diffusing agent system 25-35 parts by weight, functional additive combination 12-18 parts by weight. The acrylic copolymer matrix is ​​made of the following monomers: 455-475 parts by weight of methyl methacrylate, 270-288 parts by weight of butyl acrylate, 134-144 parts by weight of styrene, and 44-50 parts by weight of glycidyl methacrylate. The light diffusing agent system includes: Barium sulfate, 11-13 parts by weight, with a particle size of 75-85 nm; 9-11 parts by weight of silicon dioxide with a particle size of 95-105 nm; 7-9 parts by weight of polymethyl methacrylate microspheres with a particle size of 2.8-3.2 μm; The functional adjuvant combination includes: 2.5-3.5 parts by weight of UV stabilizer compound system; Antioxidant synergistic system: 3.5-4.5 parts by weight; 7-9 parts by weight of surface conditioner.

2. The highly uniform quantum dot diffusion plate according to claim 1, characterized in that, The CdSe / ZnS core-shell structured quantum dots include: The core layer contains 16-18 parts by weight of CdSe with a particle size of 3.3-3.7 nm. The shell contains 7-9 parts by weight of ZnS, with a shell thickness of 0.4-0.6 nm.

3. The highly uniform quantum dot diffusion plate according to claim 1, characterized in that, The UV stabilizer compound system includes: Tinuvin® 1577 1.6-2.0 parts by weight; Tinuvin® 329 0.9-1.5 parts by weight; The antioxidant synergistic system includes: Ionol® BHT 1.4-1.8 parts by weight; Irgafos® 168 1.2-1.6 parts by weight; Irganox® PS 802 0.9-1.1 parts by weight; The surface conditioner includes: Silwet® L-7602 1.8-2.2 parts by weight; Pluronic® F-127 1.8-2.2 parts by weight; 1.8-2.2 parts by weight of 4-methoxyphenol; Sodium polymethacrylate, 1.8-2.2 parts by weight.

4. The method for preparing a highly uniform quantum dot diffusion plate according to any one of claims 1-3, characterized in that, Includes the following steps: Step (1): Prepare the acrylic copolymer matrix; Step (2): Prepare the quantum dot diffusion layer; Step (3): Bond the quantum dot diffusion layer to the substrate; Step (2) includes: (2.1) The light-diffusing agent is ultrasonically dispersed in toluene at a frequency of 35-45 kHz, a temperature of 23-27 °C, and a time of 25-35 minutes; (2.2) Add the quantum dot dispersion and functional additive combination in sequence, and stir and mix at 130-170 rpm for 60 minutes; (2.3) Add the acrylic copolymer obtained in step (1) and stir at 30±2℃ for 120 minutes; The quantum dot diffusion layer obtained in step (2) undergoes three stages of drying: First step: Dry at 35-45℃ for 12-18 minutes; Second step: Dry at 55-65℃ for 18-22 minutes; Third step: Dry at 75-85℃ for 8-12 minutes; Step (3) includes: (3.1) Perform plasma cleaning on the substrate with a power of 35-45W for 25-35 seconds; (3.2) Bonding is performed at 83-87℃ and 0.55-0.65MPa for 2.5-3.5 minutes; (3.3) After naturally cooling to room temperature, age at 55-65℃ for 22-26 hours.

5. The preparation method according to claim 4, characterized in that, Step (1) includes: (1.1) The monomers are purified by vacuum distillation at a pressure of 90-110 mmHg, wherein the distillation temperature of methyl methacrylate is 33-37℃, the distillation temperature of butyl acrylate is 63-67℃, and the distillation temperature of styrene is 43-47℃. (1.2) Methyl methacrylate, butyl acrylate, styrene and glycidyl methacrylate are added dropwise at 70-80℃ according to the formula ratio. Then, 2.8-3.2 parts by weight of azobisisobutyronitrile are added and the mixture is reacted at 70-80℃ for 3.5-4.5 hours.

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