High-temperature resistant quantum dot diffusion plate and its preparation method

Abstract

This invention relates to the field of quantum dot diffuser technology, and more particularly to a high-temperature resistant quantum dot diffuser and its preparation method. By weight, it comprises the following components: 90-99.9 parts of diffuser particles; 0.1-10 parts of quantum dots; and 0.1-5 parts of stabilizer. The stabilizer includes at least one of nitrile radical light stabilizers, hindered amine light stabilizers, and hydroquinone light stabilizers. The multi-level scattering structure not only provides a high transmittance of over 90%, but also achieves an ultra-low haze of less than 1.5%. This significant improvement in optical performance stems from the precise control of the refractive index gradient and stress field distribution. The modified interface layer exhibits excellent stress buffering capacity, maintaining over 98% integrity during thermal cycling from -40°C to 120°C. In particular, the gradient structure of the interface layer effectively suppresses thermal stress concentration, significantly improving the reliability of the product.

Description

Technical Field

[0001] This invention relates to the field of quantum dot diffusion plate technology, and more particularly to high-temperature resistant quantum dot diffusion plates and their preparation methods. Background Technology

[0002] In recent years, quantum dot diffusers have gained widespread attention in the field of display lighting due to their excellent optical performance and color reproduction. However, existing quantum dot diffusers generally suffer from insufficient heat resistance and poor photostability, which severely restricts their practical application.

[0003] Existing technologies primarily use silica with a single particle size as the diffusing particles. This structural design results in low light scattering efficiency and a tendency to form backscattering, reducing transmittance. Furthermore, traditional surface modification techniques often employ only a single coupling agent, failing to form an effective gradient transition layer at the interface, leading to thermal stress concentration and interface delamination. More critically, currently widely used single-type light stabilizers struggle to cope with complex aging mechanisms, especially at high temperatures where the light efficiency of quantum dots rapidly declines.

[0004] Therefore, there is an urgent need to develop a new type of high-temperature resistant quantum dot diffusion plate to solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the above problems, this invention provides a high-temperature resistant quantum dot diffusion plate and its preparation method.

[0006] The purpose of this invention is to provide a high-temperature resistant quantum dot diffusion plate, comprising the following components by weight:

[0007] 90-99.9 parts of diffused particles;

[0008] Quantum dots, 0.1-10 parts;

[0009] Stabilizer 0.1-5 parts;

[0010] The stabilizer includes at least one of nitroxide radical light stabilizers, hindered amine light stabilizers, and hydroquinone light stabilizers.

[0011] Preferably, the diffused particles include:

[0012] Main component: 85-95 parts of surface-modified silica microspheres;

[0013] Assisted diffusion components: 2-5 parts of nano-alumina and 3-10 parts of nano-zirconia;

[0014] The surface-modified silica microspheres have a particle size D50 of 1.5-2.5 μm and a sphericity of not less than 0.95.

[0015] Preferably, the surface-modified silica microspheres are modified using the following coupling agent:

[0016] γ-aminopropyltriethoxysilane 1.0-2.0 wt%;

[0017] γ-Methacryloxypropyltrimethoxysilane 0.3-0.8 wt%;

[0018] Wherein, wt% is the mass percentage relative to the silica microspheres.

[0019] Preferably, the quantum dots are CdSe / ZnS core-shell structured quantum dots, comprising:

[0020] CdSe cores, with a particle size of 3-4 nm;

[0021] The ZnS shell has a thickness of 1.0-1.4 nm;

[0022] Surface ligands: 70-80 wt% oleylamine and 20-30 wt% octadecene.

[0023] Preferably, the stabilizer comprises: a nitrogen oxide radical light stabilizer: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical, 0.05-2 parts; a hindered amine light stabilizer: Tinuvin 770 60-70wt% and Chimassorb 944 30-40wt%, totaling 0.03-2 parts; and a hydroquinone light stabilizer: Irganox 1010, 0.02-1 part.

[0024] A method for preparing the high-temperature resistant quantum dot diffusion plate includes the following steps:

[0025] Step (1): Surface modification of diffused particles;

[0026] Step (2): Quantum dot surface treatment;

[0027] Step (3): Stabilizer preparation;

[0028] Step (4): Preparation of composite materials.

[0029] Preferably, step (1) includes:

[0030] (1a) The silica microspheres were vacuum dried at 80±2℃ for 12±0.5h;

[0031] (1b) Prepare a coupling agent solution and hydrolyze it at 30±2℃ for 2h;

[0032] (1c) Surface modification reaction was carried out at a temperature of 30±2℃ for 3±0.2h;

[0033] (1d) Centrifuge, wash with ethanol 3 times, and vacuum dry at 60±2℃ for 8±0.5h.

[0034] Preferably, step (2) includes:

[0035] (2a) CdSe / ZnS quantum dots were dispersed in n-hexane at a concentration of 1.0 ± 0.1 wt%.

[0036] (2b) Surface ligand exchange was performed at 45±2℃ for 4±0.2h;

[0037] (2c) Centrifuge at 10,000 rpm for 10 min and wash with methanol 3 times.

[0038] Preferably, step (3) includes:

[0039] (3a) Prepare solutions of the three stabilizers respectively;

[0040] (3b) Mix according to the formula at 25±2℃, stirring at 200±20rpm for 60±5min;

[0041] (3c) Ultrasonic dispersion, power 150W, time 20±2min.

[0042] Preferably, step (4) includes:

[0043] (4a) Add the modified diffusion particles to the epoxy resin in 3-5 portions at a temperature of 40±2℃ and a stirring speed of 300±20rpm.

[0044] (4b) Add quantum dot solution dropwise at a rate of 2 ± 0.2 mL / min at a temperature of 35 ± 2 °C;

[0045] (4c) Add stabilizer solution, temperature 30±2℃, stirring speed 200±20rpm;

[0046] (4d) Vacuum degassing, pressure not greater than 0.05MPa, time 20±2min;

[0047] (4e) Add curing agent at an equivalent ratio of 1.0-1.1;

[0048] (4f) Curing is carried out, including two stages: heat preservation at 80±2℃ for 2 hours and heat preservation at 120±2℃ for 4 hours.

[0049] Firstly, in terms of diffusion system design, a synergistic structure of nano-alumina and nano-zirconia with silica microspheres was creatively introduced. From the perspective of molecular orbital theory, the 3p orbitals of Al₂O₃ and the 4d orbitals of ZrO₂ form an energy level gradient with the 3p orbitals of SiO₂. This electronic structure characteristic directly leads to the gradient distribution of refractive index. Simultaneously, the differences in lattice constants among the three oxides create a nanoscale stress field, effectively preventing particle aggregation.

[0050] Secondly, the two-component coupling agent system developed in this invention possesses a unique interface regulation mechanism. The amino terminus of γ-aminopropyltriethoxysilane forms an initial bond with the oxide surface through hydrogen bonding and electrostatic interactions, while the unsaturated double bond of γ-methacryloyloxypropyltrimethoxysilane participates in the free radical crosslinking reaction of the matrix. This dual-action mechanism forms a nanolayer with gradient transition characteristics at the interface, and the degree of restriction on the movement of its molecular chains exhibits a spatial gradient distribution.

[0051] What is even more innovative is the multi-stabilizer system designed in this invention. Analysis of the free radical reaction mechanism shows that the unpaired electrons of nitrile and oxyradical stabilizers can rapidly capture free radicals generated by photo-oxidation, while hindered amine light stabilizers provide continuous protection through reversible redox cycles. In particular, the benzene ring conjugated system of phenolic antioxidants can effectively dissipate heat energy, and its steric hindrance effect can also inhibit the thermal motion of the molecular chain. These three stabilizers form a complementary protective network in both space and energy levels, achieving comprehensive protection for quantum dots.

[0052] Through the above-described innovative design, this invention achieves several unexpected technical effects:

[0053] First, the multi-level scattering structure not only provides high transmittance of over 90%, but also achieves ultra-low haze of less than 1.5%. This significant improvement in optical performance stems from the precise control of the refractive index gradient and stress field distribution.

[0054] Secondly, the modified interface layer exhibits excellent stress buffering capacity, maintaining over 98% integrity during thermal cycling from -40℃ to 120℃. In particular, the gradient structure of the interface layer effectively suppresses thermal stress concentration, significantly improving product reliability.

[0055] Furthermore, the multi-stabilizer system achieved an accelerated aging life exceeding 14,000 hours, a breakthrough attributed to a synergistic protection mechanism at the molecular level. Notably, the steric hindrance effect between stabilizer molecules unexpectedly increased the glass transition temperature of the matrix.

[0056] Finally, the optimized preparation process of this invention, especially the stepped temperature curing technology, significantly improves the integrity of the cross-linked network. Dynamic mechanical analysis shows that this network structure exhibits stable mechanical properties over a wide temperature range, providing a reliable guarantee for the practical application of the product.

[0057] In summary, this invention, through multiple innovative designs and process optimizations, successfully solved key problems in existing technologies, achieving a comprehensive improvement in optical performance and durability. These technological breakthroughs not only expand the application fields of quantum dot diffusers but also provide new technical ideas for the development of related materials. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0059] Example 1

[0060] This embodiment provides a high-temperature resistant quantum dot diffusion plate and its preparation method. First, the high-temperature resistant quantum dot diffusion plate of this embodiment comprises the following components by weight: 99.5 parts of diffusion particles, 0.3 parts of quantum dots, and 0.2 parts of stabilizer.

[0061] The diffused particles comprise: 94 parts of surface-modified silica microspheres (particle size D50 of 1.5 μm, sphericity of 0.98), 2 parts of nano-alumina (particle size 35 nm), and 3 parts of nano-zirconia (particle size 45 nm). Preferably, the surface-modified silica microspheres have a large specific surface area (6.2 m²). 2 / g) and a moderate surface silanol group density (3.2 groups / nm) 2 This structural feature is conducive to the formation of a uniform surface modification layer and improves compatibility with the substrate.

[0062] The quantum dots employ a CdSe / ZnS core-shell structure, wherein the CdSe core has a particle size of 3.0 nm, the ZnS shell thickness is 1.0 nm, and the surface ligand composition is 75 wt% oleylamine and 25 wt% octadecene. This core-shell structure design can effectively improve the quantum yield and stability of the quantum dots, while the optimized ratio of surface ligands can significantly improve their dispersibility in the matrix.

[0063] The stabilizers comprise: 0.08 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical, Tinuvin 770 and Chimassorb 944 (mass ratio 65:35, total 0.07 parts), and 0.05 parts of Irganox 1010. This multi-stabilizer system forms a comprehensive protective network through synergistic effects: nitroxide radicals provide rapid free radical scavenging capability, hindered amine light stabilizers ensure long-term photostability, and phenolic antioxidants provide continuous antioxidant protection.

[0064] The method for preparing the high-temperature resistant quantum dot diffusion plate in this embodiment includes the following steps:

[0065] Step (1) Surface modification of diffusion particles

[0066] First, the silica microspheres were vacuum-dried at 78 °C for 12.5 h (vacuum degree 0.09 MPa), followed by plasma treatment (200 W, 30 s). Next, a coupling agent solution was prepared: γ-aminopropyltriethoxysilane (1.8 wt%) and γ-methacryloyloxypropyltrimethoxysilane (0.5 wt%) were dissolved in an ethanol / water (95:5 v / v) mixture and hydrolyzed at 28 °C for 2 h, during which the pH was adjusted to 4.8 using acetic acid. Then, a surface modification reaction was carried out at 30 °C for 3.2 h with stirring maintained at 280 rpm. Finally, the microspheres were centrifuged at 8000 rpm for 15 min, washed three times with anhydrous ethanol, and vacuum-dried at 58 °C for 8.5 h.

[0067] Step (2) Quantum dot surface treatment

[0068] CdSe / ZnS quantum dots were dispersed in n-hexane (0.9 wt%) and sonicated at 15 °C (300 W, 40 kHz) for 30 min. Subsequently, surface ligand exchange was performed at 45 °C for 4 h under nitrogen protection throughout. Finally, the mixture was centrifuged at 10,000 rpm for 10 min and washed three times with methanol to obtain the surface-modified quantum dots.

[0069] Step (3) Stabilizer preparation

[0070] Solutions of three stabilizers were prepared separately: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical was dissolved in tetrahydrofuran (2.0 wt%) and sonicated at 30 °C for 15 min; a hindered amine light stabilizer was dissolved in a toluene / ethanol (7:3) mixed solvent (3.0 wt%) and stirred at 40 °C for 60 min; Irganox 1010 was dissolved in ethyl acetate (1.5 wt%) and stirred at 35 °C until completely dissolved. Then, the three solutions were mixed sequentially at 25 °C according to the specified ratio, stirred at 200 rpm for 65 min, and finally ultrasonically dispersed (150 W, 20 min).

[0071] Step (4) Preparation of composite materials

[0072] First, the epoxy resin was degassed under vacuum at 60℃ for 30 min (vacuum degree 0.05 MPa). Then, the modified diffusion particles were added to the epoxy resin in four batches, with the temperature controlled at 40℃ and the stirring speed at 300 rpm, with each batch added 10 min apart. Next, a quantum dot solution was added dropwise at a rate of 2.0 mL / min, at 35℃ and the stirring speed at 250 rpm. Then, a stabilizer solution was added, and the mixture was stirred at 30℃ for 20 min before being degassed under vacuum. Finally, a curing agent (equivalent ratio 1.05) was added, and curing was carried out under nitrogen protection: the temperature was raised to 80℃ for 2 h and then raised to 120℃ for 4 h, with both heating and cooling rates controlled at 1.5℃ / min.

[0073] Example 2

[0074] This embodiment provides a high-temperature resistant quantum dot diffusion plate and its preparation method. The high-temperature resistant quantum dot diffusion plate of this embodiment comprises the following components by weight: 90 parts diffusion particles, 8 parts quantum dots, and 2 parts stabilizer.

[0075] Further, the diffused particles comprise: 85 parts of surface-modified silica microspheres (particle size D50 of 2.5 μm, sphericity of 0.95), 4 parts of nano-alumina (particle size 45 nm), and 9 parts of nano-zirconia (particle size 55 nm). Preferably, in this embodiment of the invention, the specific surface area of ​​the surface-modified silica microspheres is 4.8 m². 2 / g, surface silanol group density is 2.8 units / nm 2 This structural feature, combined with nano-alumina and nano-zirconia, forms a gradient refractive index structure, which effectively improves light scattering efficiency.

[0076] The quantum dots employ a CdSe / ZnS core-shell structure, wherein the CdSe core has a particle size of 4.0 nm, the ZnS shell thickness is 1.4 nm, and the surface ligand composition is 80 wt% oleylamine and 20 wt% octadecene. The larger core size and shell thickness design enable a wider spectral tuning range while providing better photochemical stability.

[0077] The stabilizers comprise: 1.5 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical, Tinuvin 770 and Chimassorb 944 (mass ratio 70:30, total 0.3 parts), and 0.2 parts of Irganox 1010. In this formulation, the high content of hindered amine light stabilizers provides stronger photo-oxidative protection for the quantum dots, while the synergistic effect of nitric oxide radicals and phenolic antioxidants further enhances the thermal stability of the system.

[0078] The method for preparing the high-temperature resistant quantum dot diffusion plate in this embodiment includes the following steps:

[0079] Step (1) Surface modification of diffusion particles

[0080] First, the silica microspheres were vacuum-dried at 82 °C for 11.5 h (vacuum degree 0.1 MPa), followed by plasma treatment (200 W, 60 s). Next, a coupling agent solution was prepared: γ-aminopropyltriethoxysilane (1.2 wt%) and γ-methacryloyloxypropyltrimethoxysilane (0.7 wt%) were dissolved in an ethanol / water (95:5 v / v) mixture and hydrolyzed at 32 °C for 2 h, during which the pH was adjusted to 5.2 with acetic acid. Then, a surface modification reaction was carried out at 28 °C for 2.8 h with stirring maintained at 320 rpm. Finally, the microspheres were centrifuged at 8000 rpm for 15 min, washed three times with anhydrous ethanol, and vacuum-dried at 62 °C for 7.5 h.

[0081] Step (2) Quantum dot surface treatment

[0082] CdSe / ZnS quantum dots were dispersed in n-hexane (1.1 wt%) and sonicated at 18 °C (300 W, 40 kHz) for 28 min. Surface ligand exchange was then performed at 43 °C for 3.8 h under nitrogen protection throughout. Finally, the mixture was centrifuged at 9500 rpm for 12 min and washed three times with methanol to obtain the surface-modified quantum dots.

[0083] Step (3) Stabilizer preparation

[0084] First, solutions of three stabilizers were prepared separately: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical was dissolved in tetrahydrofuran (1.8 wt%) and sonicated at 28 °C for 14 min; a hindered amine light stabilizer was dissolved in a toluene / ethanol (7:3) mixed solvent (2.8 wt%) and stirred at 38 °C for 55 min; Irganox 1010 was dissolved in ethyl acetate (1.3 wt%) and stirred at 33 °C until completely dissolved. Then, the three solutions were mixed sequentially at 27 °C according to the specified ratio, stirred at 220 rpm for 55 min, and finally ultrasonically dispersed (140 W, 22 min).

[0085] Step (4) Preparation of composite materials

[0086] First, the epoxy resin was degassed under vacuum at 58℃ for 35 min (vacuum degree 0.04 MPa). Then, the modified diffusion particles were added to the epoxy resin in 5 portions, with the temperature controlled at 38℃ and the stirring speed at 320 rpm, with each addition 9 min apart. Next, a quantum dot solution was added dropwise at a rate of 1.8 mL / min, at 33℃ and the stirring speed at 270 rpm. Then, a stabilizer solution was added, and the mixture was stirred for 25 min before being degassed under vacuum. Finally, a curing agent (equivalent ratio 1.1) was added, and curing was carried out under nitrogen protection: the temperature was raised to 78℃ for 2.2 h and then raised to 118℃ for 4.2 h, with both heating and cooling rates controlled at 1.3℃ / min.

[0087] Example 3

[0088] This embodiment provides a high-temperature resistant quantum dot diffusion plate and its preparation method. The high-temperature resistant quantum dot diffusion plate of this embodiment comprises the following components by weight: 95 parts diffusion particles, 3 parts quantum dots, and 2 parts stabilizer.

[0089] In this embodiment, the diffused particles comprise: 88 parts of surface-modified silica microspheres (particle size D50 of 2.0 μm, sphericity of 0.97), 3 parts of nano-alumina (particle size 40 nm), and 4 parts of nano-zirconia (particle size 50 nm). Specifically, the specific surface area of ​​the surface-modified silica microspheres is 5.5 m². 2 / g, surface silanol group density is 3.0 units / nm 2 This moderate level of surface activity is conducive to achieving the best balance between modification effect and dispersibility.

[0090] The quantum dots employ a CdSe / ZnS core-shell structure, wherein the CdSe core has a particle size of 3.5 nm, the ZnS shell thickness is 1.2 nm, and the surface ligand composition is 72 wt% oleylamine and 28 wt% octadecene. This medium-sized core-shell structure achieves a good balance between spectral modulation and stability, and the optimization of the ligand ratio further improves its dispersion uniformity in the matrix.

[0091] The stabilizer comprises: 0.8 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical, Tinuvin 770 and Chimassorb 944 (mass ratio 67:33, total 0.8 parts), and 0.4 parts of Irganox 1010. In this embodiment, the synergistic effect of the three stabilizers forms a multi-layered protective system: short-term photostability, long-term antioxidant effect, and thermal stability are comprehensively guaranteed.

[0092] The method for preparing the high-temperature resistant quantum dot diffusion plate in this embodiment includes the following steps:

[0093] Step (1) Surface modification of diffusion particles

[0094] First, the silica microspheres were vacuum-dried at 80 °C for 12 h (vacuum degree 0.08 MPa), followed by plasma treatment (200 W, 45 s). Next, a coupling agent solution was prepared: γ-aminopropyltriethoxysilane (1.5 wt%) and γ-methacryloyloxypropyltrimethoxysilane (0.6 wt%) were dissolved in an ethanol / water (95:5 v / v) mixture and hydrolyzed at 30 °C for 2 h, during which the pH was adjusted to 5.0 with acetic acid. Then, a surface modification reaction was carried out at 29 °C for 3.0 h with stirring at 300 rpm. Finally, the microspheres were centrifuged at 8000 rpm for 15 min, washed three times with anhydrous ethanol, and vacuum-dried at 60 °C for 8 h.

[0095] Step (2) Quantum dot surface treatment

[0096] CdSe / ZnS quantum dots were dispersed in n-hexane (1.0 wt%) and sonicated at 17 °C (300 W, 40 kHz) for 29 min. Surface ligand exchange was then performed at 44 °C for 4.2 h under nitrogen protection throughout. Finally, the mixture was centrifuged at 9800 rpm for 11 min and washed three times with methanol to obtain the surface-modified quantum dots.

[0097] Step (3) Stabilizer preparation

[0098] First, solutions of three stabilizers were prepared separately: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical was dissolved in tetrahydrofuran (1.9 wt%) and sonicated at 29 °C for 16 min; a hindered amine light stabilizer was dissolved in a toluene / ethanol (7:3) mixed solvent (2.9 wt%) and stirred at 39 °C for 58 min; Irganox 1010 was dissolved in ethyl acetate (1.4 wt%) and stirred at 34 °C until completely dissolved. Then, the three solutions were mixed sequentially at 26 °C according to the specified ratio, stirred at 210 rpm for 60 min, and finally ultrasonically dispersed (145 W, 21 min).

[0099] Step (4) Preparation of composite materials

[0100] First, the epoxy resin was degassed under vacuum at 59℃ for 32 min (vacuum degree 0.045 MPa). Then, the modified diffusion particles were added to the epoxy resin in four batches, with the temperature controlled at 39℃ and the stirring speed at 310 rpm, with each batch added 10 min apart. Next, a quantum dot solution was added dropwise at a rate of 1.9 mL / min, at a temperature of 34℃ and a stirring speed of 260 rpm. Then, a stabilizer solution was added, and the mixture was stirred for 22 min before being degassed under vacuum. Finally, a curing agent (equivalent ratio 1.08) was added, and curing was carried out under nitrogen protection: the temperature was raised to 79℃ for 2.1 h and then raised to 119℃ for 4.1 h, with both heating and cooling rates controlled at 1.4℃ / min.

[0101] Example 4

[0102] This embodiment provides a high-temperature resistant quantum dot diffusion plate and its preparation method. The high-temperature resistant quantum dot diffusion plate of this embodiment comprises the following components by weight: 92 parts diffusion particles, 6 parts quantum dots, and 5 parts stabilizer.

[0103] In this embodiment of the invention, the diffused particles comprise: 90 parts of surface-modified silica microspheres (particle size D50 of 1.8 μm, sphericity of 0.96), 5 parts of nano-alumina (particle size 42 nm), and 6 parts of nano-zirconia (particle size 52 nm). Specifically, the specific surface area of ​​the surface-modified silica microspheres is 5.8 m². 2 / g, surface silanol group density is 2.6 units / nm 2 Preferably, this composition ratio enables the inorganic particles to form a multi-level scattering structure, while the introduction of nano-alumina and nano-zirconia further optimizes the optical performance.

[0104] The quantum dots employ a CdSe / ZnS core-shell structure, wherein the CdSe core has a particle size of 3.8 nm, the ZnS shell thickness is 1.3 nm, and the surface ligand composition is 78 wt% oleylamine and 22 wt% octadecene. Notably, this size ratio enables a high quantum yield, while the optimized surface ligand ratio effectively improves the compatibility of the quantum dots in the matrix.

[0105] The stabilizers comprise: 2.0 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical, Tinuvin 770 and Chimassorb 944 (mass ratio 68:32, total 2.0 parts), and 1.0 parts of Irganox 1010. Significantly, this high-content stabilizer system ensures the long-term stability of the quantum dots through multiple protection mechanisms: nitroxide radicals provide immediate protection, hindered amine light stabilizers provide continuous protection, and phenolic antioxidants supplement thermal oxidation protection.

[0106] The method for preparing the high-temperature resistant quantum dot diffusion plate in this embodiment includes the following steps:

[0107] Step (1) Surface modification of diffusion particles

[0108] First, the silica microspheres were vacuum-dried at 81 °C for 11.8 h (vacuum degree 0.095 MPa), followed by plasma treatment (200 W, 50 s). Next, a coupling agent solution was prepared: γ-aminopropyltriethoxysilane (1.6 wt%) and γ-methacryloyloxypropyltrimethoxysilane (0.4 wt%) were dissolved in an ethanol / water (95:5 v / v) mixture and hydrolyzed at 31 °C for 2 h, during which the pH was adjusted to 5.1 with acetic acid. Then, a surface modification reaction was carried out at 31 °C for 3.1 h with stirring maintained at 290 rpm. Finally, the microspheres were centrifuged at 8000 rpm for 15 min, washed three times with anhydrous ethanol, and vacuum-dried at 61 °C for 8.2 h.

[0109] Step (2) Quantum dot surface treatment

[0110] CdSe / ZnS quantum dots were dispersed in n-hexane (1.0 wt%) and sonicated at 16 °C (300 W, 40 kHz) for 31 min. Surface ligand exchange was then performed at 42 °C for 4.1 h under nitrogen protection throughout. Finally, the mixture was centrifuged at 9600 rpm for 11 min and washed three times with methanol to obtain the surface-modified quantum dots.

[0111] Step (3) Stabilizer preparation

[0112] First, solutions of three stabilizers were prepared separately: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxo radical was dissolved in tetrahydrofuran (1.7 wt%) and sonicated at 31 °C for 16 min; a hindered amine light stabilizer was dissolved in a toluene / ethanol (7:3) mixed solvent (3.0 wt%) and stirred at 41 °C for 62 min; and Irganox 1010 was dissolved in ethyl acetate (1.6 wt%) and stirred at 36 °C until completely dissolved. Then, the three solutions were mixed sequentially at 28 °C according to the specified ratio, with stirring at 215 rpm for 58 min, and finally ultrasonically dispersed (148 W, 19 min).

[0113] Step (4) Preparation of composite materials

[0114] First, the epoxy resin was degassed under vacuum at 61℃ for 33 min (vacuum degree 0.048 MPa). Then, the modified diffusion particles were added to the epoxy resin in four batches, with the temperature controlled at 41℃ and the stirring speed at 305 rpm, with each addition 9.5 min apart. Next, a quantum dot solution was added dropwise at a rate of 2.1 mL / min, at 36℃ and with the stirring speed at 255 rpm. Then, a stabilizer solution was added, and the mixture was stirred for 23 min before being degassed under vacuum. Finally, a curing agent (equivalent ratio 1.06) was added, and curing was carried out under nitrogen protection: the temperature was raised to 81℃ and held for 1.9 h, then raised to 121℃ and held for 3.9 h, with both heating and cooling rates controlled at 1.2℃ / min.

[0115] Comparative Example 1 (corresponding to Example 1)

[0116] This comparative example uses the same preparation process, only changing the component ratios, to verify the synergistic effect of the stabilizer system. By weight, it includes: 99.8 parts of diffused particles and 0.2 parts of quantum dots, excluding stabilizer. The composition of the diffused particles is the same as in Example 1.

[0117] Under the same preparation conditions, due to the lack of a stabilizer system, the quantum dot diffusion plate exhibited a 35% decrease in quantum efficiency during the 100℃ / 1000h accelerated aging test, significantly lower than the 8% decrease in Example 1. This fully demonstrates that the multi-stabilizer system designed in this invention plays a decisive role in the thermal stability of quantum dots. In particular, the synergistic effect of the three stabilizers forms a three-dimensional protective network, significantly improving the heat resistance of the product.

[0118] Comparative Example 2 (corresponding to Example 2)

[0119] This comparative example verifies the effect of the composition of the diffused particles on optical properties. The composition ratio is: 90 parts diffused particles (containing only surface-modified silica microspheres), 8 parts quantum dots, and 2 parts stabilizer.

[0120] Due to the lack of a gradient refractive index structure constructed from nano-alumina and nano-zirconia, the product's transmittance was only 82%, significantly lower than the 90% of Example 2. This verifies the importance of the multi-level scattering structure designed in this invention for optimizing optical performance. Furthermore, scanning electron microscopy revealed that the diffusion system with a single particle size is prone to aggregation, which is detrimental to uniform light scattering.

[0121] Comparative Example 3 (corresponding to Example 3)

[0122] This comparative study examines the importance of surface ligands for quantum dots. Keeping other conditions constant, the surface ligands for the quantum dots were changed to a single oleylamine. The results show that the product exhibits significant phase separation in the matrix, resulting in poor quantum dot dispersion. This directly leads to decreased luminescence uniformity, with a color deviation exceeding ±0.05, compared to only ±0.02 in Example 3. This fully demonstrates the crucial role of the two-component surface ligand system designed in this invention in improving the compatibility of quantum dots.

[0123] Comparative Example 4 (corresponding to Example 3)

[0124] This comparative example primarily verifies the criticality of the surface modification process. While maintaining the same component ratio, the plasma pretreatment step for diffused particles was omitted, and the coupling agent was replaced with a single γ-aminopropyltriethoxysilane (1.5 wt%). The preparation process was carried out according to Example 3, but the surface modification temperature was reduced to 25°C, and the time was shortened to 2 hours.

[0125] Infrared spectroscopy and X-ray photoelectron spectroscopy analysis showed that the surface modification of the diffused particles in Comparative Example 4 was significantly insufficient, with a silanol group conversion rate of only 65%, far lower than the 92% in Example 3. This directly led to a decrease in the interfacial bonding strength between the diffused particles and the matrix. After thermal cycling tests (-40℃ to 120℃, 100 cycles), the sample in Comparative Example 4 showed obvious interfacial delamination, while the sample in Example 3 remained intact. This verifies the important role of the two-component coupling agent system and precisely controlled surface modification process designed in this invention in improving product durability.

[0126] Comparative Example 5 (corresponding to Example 4)

[0127] This comparative example focuses on the impact of the stabilizer formulation process on product performance. The same component ratio as in Example 4 was used, but the three stabilizers were directly mixed and added, omitting the solution pre-mixing and ultrasonic dispersion steps. Other preparation conditions remained unchanged.

[0128] Fluorescence microscopy revealed that the stabilizer in Comparative Example 5 was unevenly distributed and exhibited significant aggregation. This resulted in insufficient protection in localized areas, leading to uneven fading after UV aging testing (λ = 365 nm, 1000 h). In contrast, Example 4, employing an optimized stabilizer formulation process, formed a uniform molecular-level dispersion system, demonstrating excellent photostability. Transmission electron microscopy (TEM) further confirmed that the three-step formulation process designed in this invention can achieve uniform distribution of the stabilizer at the nanoscale, thereby achieving the best synergistic protective effect.

[0129] Comparative Example 6 (corresponding to Example 2)

[0130] This comparative example verifies the effect of curing process parameters on product performance. The component ratios are the same as in Example 2, but a single-stage curing process is used: direct curing at 120°C for 6 hours. Other preparation conditions remain unchanged.

[0131] Dynamic mechanical analysis results show that the sample of Comparative Example 6 exhibits significant internal stress concentration, with a glass transition temperature range spanning 25°C. In contrast, Example 2, employing a stepped temperature curing process, controlled this range within 12°C. Furthermore, thermogravimetric analysis revealed that Comparative Example 6 experienced an 8% weight loss at 250°C, while Example 2 only suffered a 3% loss. This fully demonstrates the significant role of the two-stage curing process designed in this invention for forming a complete cross-linked network structure.

[0132] Based on the systematic study of the above six comparative examples, the following conclusions can be drawn:

[0133] 1. Synergistic effect of multiple stabilizer system: Through the verification of Comparative Example 1, it was demonstrated that the combined use of three stabilizers can form a comprehensive protective network, significantly improving the heat resistance of the product. Among them, nitrile oxide free radicals provide immediate protection, hindered amine light stabilizers ensure long-term stability, and phenolic antioxidants supplement the thermal oxidation protection capability.

[0134] 2. Optimized Design of Multi-Level Scattering Structure: The results of Comparative Example 2 show that the three-component diffusion system designed in this invention can form a gradient refractive index structure, effectively improving light scattering efficiency and transmittance. This multi-level structure design plays a decisive role in achieving efficient and uniform optical performance.

[0135] 3. Innovative surface modification process: Studies of Comparative Examples 3 and 4 confirm that the two-component surface modification system developed in this invention, combined with optimized process parameters, can significantly improve interfacial bonding strength and product durability.

[0136] 4. Optimization of stabilizer formulation process: Through the verification of Comparative Example 5, it was proved that the three-step formulation process designed in this invention is crucial for achieving uniform dispersion of the stabilizer, which directly affects the light stability and service life of the product.

[0137] 5. Precise control of curing process: The results of Comparative Example 6 show that the stepped temperature curing process used in this invention can effectively reduce internal stress and form a more complete cross-linked network structure, thereby improving the thermal stability of the product.

[0138] The above comparative study fully demonstrates the innovation of this invention in terms of formula design and process optimization. Significant synergistic effects are formed among the various technical features, which together ensure the overall performance of the product.

[0139] To comprehensively evaluate the performance characteristics of the high-temperature resistant quantum dot diffusion plate of this invention, the following systematic testing scheme was designed based on the requirements for polymer material testing and characterization:

[0140] Testing and characterization methods:

[0141] 1. Optical Performance Testing: The transmittance of the samples was tested using a Shimadzu UV-3600Plus UV-Vis spectrophotometer (Japan), and the haze was tested using an integrating sphere. Test conditions: room temperature 25±2℃, relative humidity 45±5%, incident light wavelength 400-700nm, scan rate 300nm / min, slit width 2nm. Fluorescence performance was tested using an Edinburgh FLS-1000 fluorescence spectrometer, with an excitation wavelength of 450nm and a detection range of 480-600nm.

[0142] 2. Thermal resistance performance evaluation: Thermomechanical properties were analyzed using a TAQ800 Dynamic Mechanical Analyzer (DMA). Test mode: single cantilever, heating rate 3℃ / min, frequency 1Hz, temperature range 25-200℃, strain 0.1%. Thermogravimetric analysis was performed using a TAQ600 synchronous thermal analyzer, heating rate 10℃ / min, nitrogen atmosphere, flow rate 50mL / min.

[0143] 3. Microstructure Characterization: The dispersion state of quantum dots was observed using a FEITecnai G2F20 transmission electron microscope with an accelerating voltage of 200 kV. Scanning electron microscopy (SEM) was performed using a ZEISS Gemini SEM 500 field emission scanning electron microscope with an operating voltage of 5 kV. The interface structure was analyzed using a Thermo Scientific K-Alpha X-ray photoelectron spectroscopy system.

[0144] 4. Stability Assessment: Light stability tests were conducted in an AtlasCi4000 xenon lamp aging chamber with an irradiation intensity of 0.55 W / m². 2 @340nm, blackboard temperature 65±3℃, relative humidity 50±5%. Heat resistance aging test was carried out in a high temperature aging chamber at 100±2℃ for 1000h.

[0145] Table 1. Optical performance test results for each sample:

[0146]

[0147]

[0148] Table 2 Results of heat resistance aging test

[0149] Sample number Light efficiency retention rate (%) after 100℃ / 1000h Thermogravimetric temperature (°C, 5% weight loss) Glass transition temperature (°C) Example 1 92.5 285 168 Example 2 91.8 282 165 Example 3 92.2 283 166 Example 4 91.5 280 164 Comparative Example 1 65.2 245 152 Comparative Example 2 68.5 248 155 Comparative Example 3 70.2 250 156 Comparative Example 4 72.5 255 158 Comparative Example 5 75.8 260 160 Comparative Example 6 78.5 265 162

[0150] Table 3. Test results of interface bonding performance and structural stability

[0151] Sample number Interfacial shear strength (MPa) Interlayer peel strength (N / m) Interface integrity after thermal cycling (%) Degree of crosslinking (%) Example 1 12.5 450 98.5 92.5 Example 2 11.8 445 97.8 91.8 Example 3 12.2 455 98.2 92.2 Example 4 12 448 97.5 91.5 Comparative Example 1 8.2 320 75.5 82.5 Comparative Example 2 7.5 310 72.8 80.8 Comparative Example 3 8 315 74.2 81.5 Comparative Example 4 7.8 325 76.5 83.2 Comparative Example 5 8.5 335 78.8 85.5 Comparative Example 6 9 340 80.5 86.8

[0152] Table 4 Results of light stability and environmental durability tests

[0153]

[0154]

[0155] A thorough analysis of the above test results reveals the following unexpected technical effects of this invention:

[0156] Firstly, regarding optical performance, the transmittance of Examples 1-4 all exceed 90%, while maintaining a low haze (<1.5%). This combination of high transmittance and low haze is difficult to achieve in existing technologies. Further investigation revealed that this is mainly due to the multi-level scattering structure designed in this invention. Through the synergistic effect of nano-alumina and nano-zirconia with silica microspheres, a unique gradient refractive index structure is formed. Transmission electron microscopy observations show that this structure can effectively reduce backscattering and significantly improve forward transmittance.

[0157] Secondly, this invention exhibits significant advantages in heat resistance. Examples 1-4 all retained over 90% of their light efficiency after aging at 100℃ for 1000h, while the comparative examples only retained 65-80%. X-ray photoelectron spectroscopy analysis revealed that this superior heat resistance stems from the synergistic protection mechanism of three stabilizers: nitroxide free radicals form a three-dimensional protective network at the molecular level; hindered amine light stabilizers provide continuous protection through a free radical capture-release cycle; and modified phenolic antioxidants form a stable physical barrier at the interface.

[0158] Furthermore, this invention exhibits superior performance in terms of interfacial structural stability. The interfacial shear strength of Examples 1-4 all exceeded 11.5 MPa, significantly higher than the 7.5-9.0 MPa of the comparative examples. Scanning electron microscopy and X-ray photoelectron spectroscopy analysis revealed that this significant improvement stems from the unique two-component coupling agent system of this invention. γ-aminopropyltriethoxysilane primarily provides chemical bonding sites, while γ-methacryloyloxypropyltrimethoxysilane participates in the cross-linking reaction of the matrix through unsaturated double bonds, forming an interfacial layer with gradient transition characteristics. This interfacial structure not only provides excellent mechanical properties but, more importantly, significantly improves thermal cycling stability; Examples 1-4 maintained over 98% interfacial integrity after 200 cycles from -40°C to 120°C.

[0159] Of particular note is the unexpected effectiveness of this invention in terms of environmental durability. The color shift of Examples 1-4 after 1000 hours of accelerated UV aging was less than 0.03, while the comparative examples generally exceeded 0.08. Fluorescence lifetime spectroscopy analysis revealed that this excellent photostability stems from the multiple protective mechanisms designed in this invention: First, nanoscale light scattering centers are formed on the surface of the modified silica microspheres, effectively reducing local light intensity; second, the three stabilizers form a complementary protective network in space, effectively capturing various free radical intermediates; finally, the optimized cross-linked network structure restricts the thermal motion of molecular chains, further enhancing the thermal stability of the system.

[0160] Furthermore, this invention also demonstrates significant advantages in accelerating aging life prediction. Analysis using the Arrhenius model revealed that the expected lifespan of Examples 1-4 all exceeded 14,000 hours, representing an improvement of over 50% compared to the control group. Further research indicates that this lifespan improvement is primarily due to the synergistic effect of the following factors:

[0161] First, the optimized surface modification process of this invention significantly improves the interfacial bonding strength and reduces interfacial cracking caused by thermal stress. Second, the multi-stabilizer system provides all-round protection through different mechanisms of action. Finally, the stepped temperature curing process forms a more complete cross-linked network structure, providing excellent structural stability.

[0162] It is worth mentioning that further dynamic mechanical analysis revealed that the samples prepared by this invention exhibit stable dynamic mechanical properties over a wide temperature range, which is of great significance for reliability in practical application environments. In particular, under cyclic thermal stress, the modified interface layer exhibits a significant stress buffering effect, effectively suppressing the initiation and propagation of microcracks.

[0163] In summary, through systematic performance testing and characterization analysis, the significant advantages of this invention in terms of optical performance, thermal stability, interface structure, and environmental durability have been fully demonstrated. These superior properties stem from multiple innovations in formulation design and process optimization, resulting in a significant synergistic effect among the various technical features. In particular, the construction of the multi-level scattering structure, the innovation of interface modification technology, and the optimization of the multiple stabilizer system have collectively achieved a comprehensive improvement in performance, providing a new technical solution for the development of high-performance quantum dot diffusers.

[0164] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A high temperature resistant quantum dot diffusion plate, characterized in that, By weight parts, including the following components: Diffusion particles 90-99.9 parts; the diffusion particles include a main part and an auxiliary diffusion component, the main part is surface modified silica microspheres 85-95 parts, the auxiliary diffusion component is nano alumina 2-5 parts and nano zirconia 3-10 parts; the surface modified silica microspheres are modified by using the following coupling agent: γ-aminopropyl triethoxysilane 1.0-2.0wt%, γ-methacryloyloxy propyl trimethoxysilane 0.3-0.8wt%, wherein the wt% is the mass percentage of the silica microspheres; Quantum dots 0.1-10 parts; the quantum dots are CdSe / ZnS core-shell structure quantum dots, the CdSe / ZnS core-shell structure quantum dots include surface ligands, the surface ligands are: oleylamine 70-80wt% and octadecene 20-30wt%; Stabilizers 0.1-5 parts; the stabilizers include 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical, 0.05-2 parts; Irganox 1010, 0.02-1 part; Tinuvin 770 60-70wt% and Chimassorb 944 30-40wt% totaling 0.03-2 parts; The preparation method of the high-temperature-resistant quantum dot diffusion plate includes the following steps: Step (1): surface modification of diffusion particles; the step (1) includes plasma pretreatment; Step (2): surface treatment of quantum dots; Step (3): stabilizer preparation; the step (3) includes ultrasonic dispersion; Step (4): composite material preparation; the step (4) includes curing, and the curing includes two stages of 80±2℃ heat preservation for 2h and 120±2℃ heat preservation for 4h.

2. The high temperature resistant quantum dot diffusion plate of claim 1, wherein, The particle size D50 of the surface modified silica microspheres is 1.5-2.5μm, and the sphericity is not less than 0.

95.

3. The high temperature resistant quantum dot diffusion plate of claim 1, wherein, The CdSe / ZnS core-shell structure quantum dots also include: CdSe core, particle size 3-4nm; ZnS shell layer, thickness 1.0-1.4nm.

4. The high temperature resistant quantum dot diffusion plate of claim 1, wherein, The step (1) includes: (1a) vacuum drying of silica microspheres at 80±2℃ for 12±0.5h; (1b) preparation of coupling agent solution, hydrolysis at 30±2℃ for 2h; (1c) surface modification reaction, temperature 30±2℃, time 3±0.2h; (1d) centrifugal separation, ethanol washing 3 times, 60±2℃ vacuum drying for 8±0.5h.

5. The high temperature resistant quantum dot diffusion plate of claim 1, wherein, The step (2) includes: (2a) dispersing CdSe / ZnS quantum dots in n-hexane, concentration 1.0±0.1wt%; (2b) surface ligand exchange at 45±2℃ for 4±0.2h; (2c) centrifugation at 10000rpm for 10min, washing with methanol 3 times.

6. The high temperature resistant quantum dot diffusion plate of claim 1, wherein, The step (3) includes: (3a) preparation of three kinds of stabilizer solutions respectively; (3b) mixing at 25±2℃ according to the proportion, stirring speed 200±20rpm, time 60±5min; (3c) ultrasonic dispersion, power 150W, time 20±2min.

7. The high temperature resistant quantum dot diffusion plate of claim 1, wherein, The step (4) includes: (4a) Add the modified diffusion particles into the epoxy resin in 3-5 times, temperature 40±2℃, stirring speed 300±20rpm; (4b) Drop the quantum dot solution, rate 2±0.2mL / min, temperature 35±2℃; (4c) Add the stabilizer solution, temperature 30±2℃, stirring speed 200±20rpm; (4d) Vacuum degassing, pressure no more than 0.05MPa, time 20±2min; (4e) Add the curing agent, equivalent ratio 1.0-1.1; (4f) Curing, including two stages of 80±2℃ for 2h and 120±2℃ for 4h.

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