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

Abstract

The invention relates to the technical field of quantum dot diffusion plates, in particular to a high-temperature-resistant quantum dot diffusion plate and a preparation method thereof, and the high-temperature-resistant quantum dot diffusion plate comprises the following components in parts by weight: 90-99.9 parts of diffusion particles; 0.1 to 10 parts of quantum dots; 0.1-5 parts of a stabilizer; wherein the stabilizer comprises at least one of a nitroxide free radical light stabilizer, a hindered amine light stabilizer and a hydroquinone light stabilizer, and the multi-stage scattering structure not only provides high light transmittance of 90% or above, but also realizes ultra-low haze of 1.5% or below. The optical performance is obviously improved from accurate regulation and control of refractive index gradient and stress field distribution; the modified interface layer shows excellent stress buffering capacity, and keeps the integrity of 98% or above in the thermal cycle process of-40 DEG C to 120 DEG C. Especially, the gradient structure of the interface layer effectively inhibits thermal stress concentration, and the reliability of the product is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dot diffusion plates, and particularly to a high-temperature resistant quantum dot diffusion plate and a preparation method thereof. Background Art

[0002] In recent years, quantum dot diffusion plates have received extensive attention in the field of display lighting due to their excellent optical properties and color performance. However, the existing quantum dot diffusion plates generally have problems such as insufficient heat resistance and poor light stability, which severely restrict their practical applications.

[0003] The prior art mainly uses silica with a single particle size as the diffusion particles. This structural design results in low light scattering efficiency and is prone to form backscattering, reducing the light transmittance. In addition, traditional surface modification techniques often only use a single coupling agent, which cannot form an effective gradient transition layer at the interface, leading to heat stress concentration and interface peeling. More critically, the currently commonly used single type of light stabilizer is difficult to cope with complex aging mechanisms. Especially in a high-temperature environment, the light efficiency of quantum dots will rapidly decay.

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

[0005] In view of the above problems, the present invention provides a high-temperature resistant quantum dot diffusion plate and a preparation method thereof.

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

[0007] 90 - 99.9 parts of diffusion particles;

[0008] 0.1 - 10 parts of quantum dots;

[0009] 0.1 - 5 parts of stabilizer;

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

[0011] Preferably, the diffusion particles include:

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

[0013] Auxiliary diffusion component: 2 - 5 parts of nano-aluminum oxide and 3 - 10 parts of nano-zirconium oxide;

[0014] Wherein, the particle size D50 of the surface-modified silica microspheres is 1.5 - 2.5 μm, and the sphericity is not less than 0.95.

[0015] Preferably, the surface-modified silica microspheres are modified with the following coupling agents:

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

[0017] 0.3 - 0.8 wt% of γ-methacryloxypropyltrimethoxysilane;

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

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

[0020] A CdSe core with a particle size of 3 - 4 nm;

[0021] A ZnS shell layer with a thickness of 1.0 - 1.4 nm;

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

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

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

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

[0026] Step (2): Surface treatment of the quantum dots;

[0027] Step (3): Preparation of the stabilizer;

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

[0029] Preferably, the step (1) includes:

[0030] (1a) Vacuum-dry the silica microspheres at 80 ± 2 °C for 12 ± 0.5 h;

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

[0032] (1c) Conduct a surface modification reaction at a temperature of 30 ± 2 °C for 3 ± 0.2 h;

[0033] (1d) Centrifugally separate and wash with ethanol three times, then vacuum dry at 60 ± 2 °C for 8 ± 0.5 h.

[0034] Preferably, step (2) includes:

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

[0036] (2b) Conduct surface ligand exchange at 45 ± 2 °C for 4 ± 0.2 h;

[0037] (2c) Centrifuge at 10000 rpm for 10 min and wash with methanol three times.

[0038] Preferably, step (3) includes:

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

[0040] (3b) Mix according to the ratio at 25 ± 2 °C, with a stirring speed of 200 ± 20 rpm for 60 ± 5 min;

[0041] (3c) Ultrasonically disperse at a power of 150 W for 20 ± 2 min.

[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 °C and a stirring speed of 300 ± 20 rpm;

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

[0045] (4c) Add the stabilizer solution at a temperature of 30 ± 2 °C and a stirring speed of 200 ± 20 rpm;

[0046] (4d) Vacuum degas at a pressure not greater than 0.05 MPa for 20 ± 2 min;

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

[0048] (4f) Conduct curing, including two stages: holding at 80 ± 2 °C for 2 h and holding at 120 ± 2 °C for 4 h.

[0049] First, in terms of the design of the diffusion system, a synergistic structure of nano - alumina and nano - zirconia with silica microspheres was creatively introduced. Analyzed from the perspective of molecular orbital theory, the 3p orbit of Al 2 O 3 and the 4d orbit of ZrO2 and SiO 2The 3p orbitals form an energy level gradient, and this characteristic of the electronic structure directly leads to a gradient distribution of the refractive index. At the same time, the differences in the lattice constants of the three oxides form a stress field at the nanoscale, effectively preventing particle agglomeration.

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

[0051] Even more innovative is the multiple stabilizer system designed in this invention. Analyzing from the free radical reaction mechanism, the unpaired electrons of nitroxide radical stabilizers can quickly capture the free radicals generated by photooxidation, while hindered amine light stabilizers provide continuous protection through a reversible redox cycle. In particular, the benzene ring conjugate system of phenolic antioxidants can effectively dissipate heat energy, and its steric effect can also inhibit the thermal movement of molecular chains. These three stabilizers form a complementary protection network in space and energy levels, achieving all-round protection of the quantum dots.

[0052] Through the above innovative designs, this invention has obtained a number of unexpected technical effects:

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

[0054] Secondly, the modified interface layer exhibits excellent stress buffering ability and maintains more than 98% integrity during the thermal cycle from -40°C to 120°C. In particular, the gradient structure of the interface layer effectively inhibits the concentration of thermal stress, significantly improving the reliability of the product.

[0055] Thirdly, the multiple stabilizer system has achieved an accelerated aging life of more than 14,000 hours, and this breakthrough progress is attributed to the synergistic protection mechanism at the molecular level. It is worth noting that the steric hindrance effect between stabilizer molecules has also unexpectedly increased the glass transition temperature of the matrix.

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

[0057] In summary, the present invention has successfully solved the key problems in the prior art through multiple innovative designs and process optimization, and achieved a comprehensive improvement in optical performance and durability. These technological breakthroughs not only expand the application field of quantum dot diffusion plates, but also provide new technical ideas for the development of related materials. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0059] Example 1

[0060] This embodiment provides a high temperature resistant quantum dot diffusion plate and a preparation method thereof. First, the high temperature resistant quantum dot diffusion plate of this embodiment includes 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 diffusion particles include: 94 parts of surface-modified silica microspheres (particle size D50 is 1.5 μm, sphericity 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 m 2 / g) and moderate surface silanol density (3.2 / nm 2 ), this structural feature is conducive to forming a uniform surface modification layer and improving the compatibility with the substrate.

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

[0063] The stabilizer includes: 0.08 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl free radical, Tinuvin770 and Chimassorb 944 (mass ratio of 65:35, total amount of 0.07 parts), and 0.05 parts of Irganox 1010. This multi-stabilizer system forms a comprehensive protection network through synergistic effects: nitroxide free radicals provide rapid free radical capture ability, hindered amine light stabilizers ensure long-term light stability, and phenolic antioxidants provide continuous antioxidant protection.

[0064] The preparation method of 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, vacuum dry the silica microspheres at 78 °C for 12.5 h (vacuum degree 0.09 MPa), and then perform plasma treatment (200 W, 30 s). Next, prepare the coupling agent solution: dissolve γ-aminopropyltriethoxysilane (1.8 wt%) and γ-methacryloxypropyltrimethoxysilane (0.5 wt%) in an ethanol / water (95:5 v / v) mixed solvent, and hydrolyze at 28 °C for 2 h. During this period, adjust the pH to 4.8 using acetic acid. Then, carry out the surface modification reaction at 30 °C for 3.2 h, and maintain the stirring speed at 280 rpm. Finally, centrifuge at 8000 rpm for 15 min, wash 3 times with anhydrous ethanol, and vacuum dry at 58 °C for 8.5 h.

[0067] Step (2) Surface treatment of quantum dots

[0068] Disperse CdSe / ZnS quantum dots in n-hexane (concentration 0.9 wt%), and perform ultrasonic treatment (300 W, 40 kHz) at 15 °C for 30 min. Then, carry out surface ligand exchange at 45 °C for 4 h, and maintain nitrogen protection throughout the process. Finally, centrifuge at 10000 rpm for 10 min, and wash 3 times with methanol to obtain surface-modified quantum dots.

[0069] Step (3) Preparation of stabilizers

[0070] Prepare solutions of three stabilizers respectively: dissolve 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical in tetrahydrofuran (2.0 wt%), and perform ultrasonic treatment at 30 °C for 15 min; dissolve hindered amine light stabilizer in a toluene / ethanol (7:3) mixed solvent (3.0 wt%), and stir at 40 °C for 60 min; dissolve Irganox 1010 in ethyl acetate (1.5 wt%), and stir at 35 °C until completely dissolved. Then, mix the three solutions in sequence at 25 °C according to the ratio, with a stirring speed of 200 rpm and a time of 65 min. Finally, perform ultrasonic dispersion (150 W, 20 min).

[0071] Step (4) Preparation of composite materials

[0072] First, the epoxy resin is degassed under vacuum at 60 °C for 30 min (vacuum degree 0.05 MPa). Then, the modified diffusion particles are added to the epoxy resin in 4 portions, with the temperature controlled at 40 °C and the stirring speed at 300 rpm, and the interval between each addition is 10 min. Next, the quantum dot solution is dropped at a rate of 2.0 mL / min, with the temperature at 35 °C and the stirring speed at 250 rpm. Then, the stabilizer solution is added, with the temperature at 30 °C, and after stirring for 20 min, it is degassed under vacuum. Finally, the curing agent (equivalent ratio 1.05) is added, and curing is carried out under nitrogen protection: keep warm at 80 °C for 2 h, raise the temperature to 120 °C and keep warm for 4 h, and the heating and cooling rates are both controlled at 1.5 °C / min.

[0073] Example 2

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

[0075] Furthermore, the diffusion particles include: 85 parts of surface-modified silica microspheres (particle size D50 is 2.5 μm, sphericity 0.95), 4 parts of nano-aluminum oxide (particle size 45 nm), and 9 parts of nano-zirconium oxide (particle size 55 nm). Preferably, in this example of the present invention, the specific surface area of the surface-modified silica microspheres is 4.8 m 2 / g, and the surface silanol group density is 2.8 per nm 2 , and this structural feature cooperates with nano-aluminum oxide and nano-zirconium oxide to form a gradient refractive index structure, effectively improving the light scattering efficiency.

[0076] The quantum dots adopt a CdSe / ZnS core-shell structure, where the particle size of the CdSe core is 4.0 nm, the thickness of the ZnS shell layer is 1.4 nm, and the surface ligand composition is 80 wt% of oleylamine and 20 wt% of octadecene. The design of a larger core size and shell layer thickness can achieve a wider spectral regulation range and at the same time provide better photochemical stability.

[0077] The stabilizer includes: 1.5 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical, Tinuvin 770 and Chimassorb 944 (mass ratio 70:30, total amount 0.3 parts), and 0.2 part of Irganox 1010. Under this ratio, the high content of hindered amine light stabilizers can provide stronger photooxidation protection for the quantum dots, and the synergistic effect of nitroxyl radicals and phenolic antioxidants further enhances the thermal stability of the system.

[0078] The preparation method of the high-temperature resistant quantum dot diffusion plate of this example includes the following steps:

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

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

[0081] Step (2) Surface treatment of quantum dots

[0082] The CdSe / ZnS quantum dots are dispersed in n-hexane (concentration 1.1 wt%), and ultrasonic treatment (300 W, 40 kHz) is carried out at 18 °C for 28 min. Subsequently, surface ligand exchange is carried out at 43 °C for 3.8 h, and nitrogen protection is maintained throughout the process. Finally, centrifugation is carried out at 9500 rpm for 12 min, washed three times with methanol, and surface-modified quantum dots are obtained.

[0083] Step (3) Preparation of stabilizers

[0084] First, solutions of three stabilizers are prepared respectively: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical is dissolved in tetrahydrofuran (1.8 wt%) and ultrasonicated at 28 °C for 14 min; hindered amine light stabilizer is dissolved in a toluene / ethanol (7:3) mixed solvent (2.8 wt%) and stirred at 38 °C for 55 min; Irganox 1010 is dissolved in ethyl acetate (1.3 wt%) and stirred at 33 °C until completely dissolved. Then, the three solutions are mixed in sequence at 27 °C according to the ratio, with a stirring speed of 220 rpm and a time of 55 min, and finally ultrasonic dispersion (140 W, 22 min) is carried out.

[0085] Step (4) Preparation of composite materials

[0086] First, vacuum degas the epoxy resin at 58 °C for 35 min (vacuum degree 0.04 MPa). Then, add the modified diffusion particles to the epoxy resin in 5 portions, control the temperature at 38 °C, and the stirring speed at 320 rpm, with an interval of 9 min each time. Next, dropwise add the quantum dot solution at a rate of 1.8 mL / min, at a temperature of 33 °C and a stirring speed of 270 rpm. Then add the stabilizer solution, at a temperature of 32 °C, stir for 25 min and then vacuum degas. Finally, add the curing agent (equivalent ratio 1.1), and cure under nitrogen protection: keep warm at 78 °C for 2.2 h, raise the temperature to 118 °C and keep warm for 4.2 h, and control the heating and cooling rates at 1.3 °C / min.

[0087] Example 3

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

[0089] In this example, the diffusion particles include: 88 parts of surface-modified silica microspheres (particle size D50 is 2.0 μm, sphericity 0.97), 3 parts of nano-aluminum oxide (particle size 40 nm), and 4 parts of nano-zirconium oxide (particle size 50 nm). In particular, the specific surface area of the surface-modified silica microspheres is 5.5 m 2 / g, and the surface silanol group density is 3.0 per nm 2 , and this medium degree of surface activity is conducive to achieving the best balance between the modification effect and dispersibility.

[0090] The quantum dots adopt a CdSe / ZnS core-shell structure, where the particle size of the CdSe core is 3.5 nm, the thickness of the ZnS shell layer 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 regulation and stability, and the optimization of the ligand ratio further improves its dispersion uniformity in the matrix.

[0091] The stabilizer includes: 0.8 part of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical, Tinuvin 770 and Chimassorb 944 (mass ratio 67:33, total amount 0.8 part), and 0.4 part of Irganox 1010. In this example, the synergistic effect of the three stabilizers forms a multi-level protection system: short-term light stability, long-term antioxidant property, and thermal stability are comprehensively guaranteed.

[0092] The preparation method of the high-temperature resistant quantum dot diffusion plate of this example comprises the following steps:

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

[0094] First, vacuum dry the silica microspheres at 80 °C for 12 h (vacuum degree 0.08 MPa), and then perform plasma treatment (200 W, 45 s). Next, prepare the coupling agent solution: dissolve γ-aminopropyltriethoxysilane (1.5 wt%) and γ-methacryloxypropyltrimethoxysilane (0.6 wt%) in an ethanol / water (95:5 v / v) mixed solvent, and hydrolyze at 30 °C for 2 h. During this period, adjust the pH to 5.0 using acetic acid. Then, carry out the surface modification reaction at 29 °C for 3.0 h, and maintain the stirring speed at 300 rpm. Finally, centrifuge at 8000 rpm for 15 min, wash 3 times with absolute ethanol, and vacuum dry at 60 °C for 8 h.

[0095] Step (2) Surface treatment of quantum dots

[0096] Disperse the CdSe / ZnS quantum dots in n-hexane (concentration 1.0 wt%), and ultrasonically treat (300 W, 40 kHz) at 17 °C for 29 min. Then, carry out surface ligand exchange at 44 °C for 4.2 h, and maintain nitrogen protection throughout the process. Finally, centrifuge at 9800 rpm for 11 min, and wash 3 times with methanol to obtain surface-modified quantum dots.

[0097] Step (3) Preparation of stabilizers

[0098] First, prepare the solutions of three stabilizers respectively: dissolve 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl in tetrahydrofuran (1.9 wt%), and ultrasonically treat at 29 °C for 16 min; dissolve the hindered amine light stabilizer in a toluene / ethanol (7:3) mixed solvent (2.9 wt%), and stir at 39 °C for 58 min; dissolve Irganox 1010 in ethyl acetate (1.4 wt%), and stir at 34 °C until completely dissolved. Then, mix the three solutions in sequence at 26 °C according to the ratio, with a stirring speed of 210 rpm and a time of 60 min, and finally carry out ultrasonic dispersion (145 W, 21 min).

[0099] Step (4) Preparation of composite materials

[0100] First, the epoxy resin is degassed under vacuum at 59 °C for 32 min (vacuum degree 0.045 MPa). Then, the modified diffusion particles are added to the epoxy resin in 4 portions, with the temperature controlled at 39 °C and the stirring speed at 310 rpm, with a 10-min interval between each addition. Next, the quantum dot solution is added dropwise at a rate of 1.9 mL / min, with the temperature at 34 °C and the stirring speed at 260 rpm. Then, the stabilizer solution is added, with the temperature at 31 °C, and after stirring for 22 min, it is degassed under vacuum. Finally, the curing agent (equivalent ratio 1.08) is added, and curing is carried out under nitrogen protection: held at 79 °C for 2.1 h, heated to 119 °C and held for 4.1 h, with both the heating and cooling rates controlled at 1.4 °C / min.

[0101] Example 4

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

[0103] In this example of the present invention, the diffusion particles include: 90 parts of surface-modified silica microspheres (particle size D50 is 1.8 μm, sphericity 0.96), 5 parts of nano-aluminum oxide (particle size 42 nm), and 6 parts of nano-zirconium oxide (particle size 52 nm). In particular, the specific surface area of the surface-modified silica microspheres is 5.8 m 2 / g, and the surface silanol group density is 2.6 per nm 2 . Preferably, this component ratio enables the inorganic particles to form a multi-level scattering structure, and the introduction of nano-aluminum oxide and nano-zirconium oxide further optimizes the optical properties.

[0104] The quantum dots adopt a CdSe / ZnS core-shell structure, where the particle size of the CdSe core is 3.8 nm, the thickness of the ZnS shell layer is 1.3 nm, and the surface ligand composition is 78 wt% oleylamine and 22 wt% octadecene. It should be noted that this size ratio can achieve a relatively high quantum yield, and the optimized surface ligand ratio effectively improves the compatibility of the quantum dots in the matrix.

[0105] The stabilizer includes: 2.0 parts of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical, Tinuvin 770 and Chimassorb 944 (mass ratio 68:32, total amount 2.0 parts), and 1.0 part of Irganox 1010. Significantly, this high-content stabilizer system ensures the long-term stability of the quantum dots through a multiple protection mechanism: the nitroxide radical provides immediate protection, the hindered amine light stabilizer achieves continuous protection, and the phenolic antioxidant supplements the thermal oxidation protection ability.

[0106] The preparation method of the high-temperature resistant quantum dot diffusion plate of this example includes the following steps:

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

[0108] First, the silica microspheres are vacuum-dried at 81 °C for 11.8 h (vacuum degree 0.095 MPa), and then plasma treatment is carried out (200 W, 50 s). Next, a coupling agent solution is prepared: γ-aminopropyltriethoxysilane (1.6 wt%) and γ-methacryloxypropyltrimethoxysilane (0.4 wt%) are dissolved in an ethanol / water (95:5 v / v) mixed solvent and hydrolyzed at 31 °C for 2 h. During this period, acetic acid is used to adjust the pH to 5.1. Then, a surface modification reaction is carried out at 31 °C for 3.1 h, and the stirring speed is maintained at 290 rpm. Finally, centrifugation is carried out at 8000 rpm for 15 min, washed three times with absolute ethanol, and vacuum-dried at 61 °C for 8.2 h.

[0109] Step (2) Surface treatment of quantum dots

[0110] The CdSe / ZnS quantum dots are dispersed in n-hexane (concentration 1.0 wt%) and ultrasonically treated (300 W, 40 kHz) at 16 °C for 31 min. Subsequently, surface ligand exchange is carried out at 42 °C for 4.1 h, and nitrogen protection is maintained throughout the process. Finally, centrifugation is carried out at 9600 rpm for 11 min, washed three times with methanol, and surface-modified quantum dots are obtained.

[0111] Step (3) Preparation of stabilizers

[0112] First, solutions of three stabilizers are prepared respectively: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical is dissolved in tetrahydrofuran (1.7 wt%) and ultrasonically treated at 31 °C for 16 min; the hindered amine light stabilizer is dissolved in a toluene / ethanol (7:3) mixed solvent (3.0 wt%) and stirred at 41 °C for 62 min; Irganox 1010 is dissolved in ethyl acetate (1.6 wt%) and stirred at 36 °C until completely dissolved. Then, the three solutions are sequentially mixed at 28 °C according to the ratio, with a stirring speed of 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°C for 33 min (vacuum degree 0.048 MPa). Then, the modified diffusion particles were added to the epoxy resin in 4 portions, with the temperature controlled at 41°C and the stirring speed at 305 rpm, with an interval of 9.5 min each time. Next, the quantum dot solution was dropped at a rate of 2.1 mL / min, with the temperature at 36°C and the stirring speed at 255 rpm. Then, the stabilizer solution was added, with the temperature at 32°C, and after stirring for 23 min, it was degassed under vacuum. Finally, the curing agent (equivalent ratio 1.06) was added, and curing was carried out under nitrogen protection: held at 81°C for 1.9 h, heated to 121°C and held for 3.9 h, and both the heating and cooling rates were controlled at 1.2°C / min.

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

[0116] This comparative example used the same preparation process, only changing the component ratios to verify the synergistic effect of the stabilizer system. By weight, it included: 99.8 parts of diffusion particles, 0.2 parts of quantum dots, and no stabilizer. Among them, the composition of the diffusion particles was the same as that in Example 1.

[0117] Under the same preparation conditions, due to the lack of protection of the stabilizer system, in the 100°C / 1000 h accelerated aging test of the prepared quantum dot diffusion plate, the quantum efficiency decreased by 35%, much lower than 8% in Example 1. This fully illustrates that the multiple stabilizer system designed in the present 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 protection network, significantly improving the heat resistance of the product.

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

[0119] This comparative example verified the influence of the diffusion particle composition on the optical properties. The component ratio was: 90 parts of diffusion particles (only containing surface-modified silica microspheres), 8 parts of quantum dots, and 2 parts of stabilizer.

[0120] Due to the lack of the gradient refractive index structure constructed by nano-aluminum oxide and nano-zirconium oxide, the light transmittance of the product was only 82%, significantly lower than 90% in Example 2. This verified the importance of the multi-level scattering structure designed in the present invention for optimizing the optical properties. Further, through scanning electron microscopy observation, it was found that the single-particle-size diffusion system was prone to agglomeration, which was not conducive to the uniform scattering of light.

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

[0122] This comparative example examines the importance of the surface ligands of quantum dots. Keeping other conditions unchanged, the surface ligands of the quantum dots were changed to a single oleylamine. The results showed that obvious phase separation occurred in the matrix of the product, and the dispersibility of the quantum dots was poor. This directly led to a decrease in luminescence uniformity, with a chromaticity deviation exceeding ±0.05, while that of Example 3 was only ±0.02. This fully demonstrated the important role of the binary surface ligand system designed in the present invention in improving the compatibility of quantum dots.

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

[0124] This comparative example mainly verifies the key nature of the surface modification process. While keeping the component ratios unchanged, the plasma pretreatment step of the diffusion particles was omitted, and at the same time, the coupling agent was changed to 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 h.

[0125] Analysis by infrared spectroscopy and X-ray photoelectron spectroscopy showed that the surface modification degree of the diffusion particles in Comparative Example 4 was significantly insufficient, and the conversion rate of silanol groups was only 65%, much lower than 92% of Example 3. This directly led to a decrease in the interfacial bonding strength between the diffusion particles and the matrix. After the thermal cycle test (-40 °C to 120 °C, 100 times), obvious interfacial delamination occurred in the sample of Comparative Example 4, while the sample of Example 3 remained intact. This verified the important role of the binary coupling agent system and precisely controlled surface modification process designed in the present invention in enhancing the durability of the product.

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

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

[0128] The results of fluorescence microscopy observation showed that the stabilizers in Comparative Example 5 were unevenly distributed and obvious agglomeration occurred. This led to insufficient protection in local areas, and uneven fading occurred after the ultraviolet aging test (λ = 365 nm, 1000 h). While in Example 4, due to the optimized preparation process of the stabilizer, a uniform molecular-level dispersion system was formed, showing excellent light stability. Energy spectrum analysis by transmission electron microscopy further confirmed that the three-step preparation process designed in the present invention could achieve uniform distribution of the stabilizer at the nanoscale, thus exerting the best synergistic protection effect.

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

[0130] This comparative example verifies the influence of curing process parameters on the product performance. The component ratio is the same as that of Example 2, but a single-stage curing process is adopted: directly curing at 120 °C for 6 h. Other preparation conditions remain unchanged.

[0131] The results of dynamic mechanical analysis show that there is obvious internal stress concentration in the sample of Comparative Example 6, and the span of the glass transition temperature range reaches 25 °C. While in Example 2, by adopting the stepwise temperature-rising curing process, this span is controlled within 12 °C. In addition, thermogravimetric analysis shows that the weight loss of Comparative Example 6 reaches 8% at 250 °C, while that of Example 2 is only 3%. This fully proves that the two-stage curing process designed by the present invention is of great significance for forming a complete crosslinked network structure.

[0132] Through the systematic study of the above 6 comparative examples, the following conclusions can be drawn:

[0133] 1. Synergistic effect of the multi-stabilizer system: Through the verification of Comparative Example 1, it is proved that the combined use of three stabilizers can form an all-round protection network, significantly improving the heat resistance of the product. Among them, nitroxide radicals provide immediate protection, hindered amine light stabilizers ensure long-term stability, and phenolic antioxidants supplement the thermal oxidation protection ability.

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

[0135] 3. Process innovation of surface modification: The studies of Comparative Examples 3 and 4 confirm that the two-component surface modification system developed by the present invention, combined with optimized process parameters, can significantly improve the interfacial bonding strength and product durability.

[0136] 4. Process optimization of stabilizer formulation: Through the verification of Comparative Example 5, it is proved that the three-step formulation process designed by the present invention is crucial for achieving uniform dispersion of the stabilizer, directly affecting the light stability and service life of the product.

[0137] 5. Precise control of the curing process: The results of Comparative Example 6 show that the stepwise temperature-rising curing process adopted by the present invention can effectively reduce internal stress and form a more complete crosslinked network structure, thereby improving the thermal stability of the product.

[0138] The above comparative studies fully prove the innovation of the present invention in formula design and process optimization. Significant synergistic effects are formed among various technical features, jointly ensuring the comprehensive performance of the product.

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

[0140] Testing and characterization methods:

[0141] 1. Optical performance testing: The transmittance of the sample was tested using a Shimadzu UV-3600Plus ultraviolet-visible spectrophotometer from Japan, and the haze was tested using an integrating sphere. Testing conditions: room temperature 25 ± 2°C, relative humidity 45 ± 5%, incident light wavelength 400 - 700 nm, scanning rate 300 nm / min, slit width 2 nm. The fluorescence performance was tested using an Edinburgh FLS-1000 fluorescence spectrometer, excitation wavelength 450 nm, detection range 480 - 600 nm.

[0142] 2. Heat resistance evaluation: A TA Q800 dynamic mechanical analyzer (DMA) was used for thermomechanical performance analysis. Testing mode: single cantilever, heating rate 3°C / min, frequency 1 Hz, temperature range 25 - 200°C, strain 0.1%. Thermogravimetric analysis was carried out using a TA Q600 synchronous thermal analyzer, heating rate 10°C / min, nitrogen atmosphere, flow rate 50 mL / min.

[0143] 3. Microstructure characterization: A FEI Tecnai G2 F20 transmission electron microscope was used to observe the dispersion state of the quantum dots, with an accelerating voltage of 200 kV. Scanning electron microscopy observations were carried out using a ZEISS Gemini SEM 500 field emission scanning electron microscope, with a working voltage of 5 kV. The interfacial structure was analyzed using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer.

[0144] 4. Stability evaluation: The light stability test was carried out in an Atlas Ci4000 xenon lamp aging chamber, with an irradiation intensity of 0.55 W / m 2 @340 nm, blackboard temperature 65 ± 3°C, relative humidity 50 ± 5%. The heat resistance aging test was carried out in a high-temperature aging chamber, with a temperature of 100 ± 2°C and a time of 1000 h.

[0145] Table 1 Test results of the optical performance of each sample:

[0146]

[0147]

[0148] Table 2 Test results of heat resistance aging performance

[0149] Sample Number Light Efficiency Retention Rate (%) after 100°C / 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 interfacial bonding performance and structural stability

[0151] Sample Number Interfacial Shear Strength (MPa) Interlaminar Peel Strength (N / m) Interface Integrity after Thermal Cycling (%) Crosslinking Degree (%) 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 Photostability and Environmental Durability Tests

[0153]

[0154]

[0155] By deeply analyzing the above test results, the present invention exhibits the following unexpected technical effects:

[0156] First of all, in terms of optical properties, the light transmittance of Examples 1-4 all exceeds 90%, while maintaining a low haze (<1.5%). This combined characteristic of high light transmittance and low haze is difficult to achieve in the prior art. Through in-depth research, it is found that this is mainly due to the multi-stage scattering structure designed in the present invention. Through the synergistic effect of nano-aluminum oxide, nano-zirconium oxide and silica microspheres, a unique gradient refractive index structure is formed. Transmission electron microscope observation shows that this structure can effectively reduce backscattering and significantly improve the forward light transmittance.

[0157] Secondly, the present invention shows significant advantages in heat resistance. The light efficiency retention rates of Examples 1-4 after aging at 100°C / 1000h all exceed 90%, while those of the comparative examples are only 65-80%. Through X-ray photoelectron spectroscopy analysis, it is found that this excellent heat resistance stems from the synergistic protection mechanism of three stabilizers: nitroxide radicals form a three-dimensional protection network at the molecular level, hindered amine light stabilizers provide continuous protection through the free radical capture-release cycle, and the modified phenolic antioxidant forms a stable physical barrier at the interface.

[0158] Furthermore, in terms of the stability of the interface structure, the present invention exhibits excellent performance. The interfacial shear strengths of Examples 1-4 all exceed 11.5 MPa, far higher than those of the comparative examples (7.5-9.0 MPa). Through scanning electron microscope and X-ray photoelectron spectroscopy analysis, it is found that this significant improvement is due to the unique two-component coupling agent system of the present invention. γ-aminopropyltriethoxysilane mainly provides chemical bonding sites, while γ-methacryloxypropyltrimethoxysilane 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 the thermal cycle stability. Examples 1-4 still maintain an interfacial integrity of more than 98% after 200 cycles from -40°C to 120°C.

[0159] It is particularly worth noting that the present invention exhibits unexpected effects in terms of environmental durability. The color deviation of Examples 1-4 after 1000 hours of ultraviolet accelerated aging is less than 0.03, while that of the comparative examples generally exceeds 0.08. Through fluorescence lifetime spectroscopy analysis, it is found that this excellent light stability stems from the multiple protection mechanisms designed in the present invention: First, nano-scale light scattering centers are formed on the surface of the modified silica microspheres, effectively reducing the local light intensity; Second, the three stabilizers form a complementary protection network in space, which can effectively capture various free radical intermediates; Finally, the optimized cross-linked network structure restricts the thermal movement of molecular chains, further enhancing the thermal stability of the system.

[0160] In addition, the present invention also shows significant advantages in the prediction of accelerated aging life. Through Arrhenius model analysis, it is found that the expected service life of Examples 1-4 exceeds 14000 hours, which is more than 50% higher than that of the comparative examples. In-depth research shows that this increase in life is mainly due to the following synergistic effects:

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

[0162] It is worth mentioning that through dynamic mechanical analysis, it is further found that the samples prepared by the present invention exhibit stable dynamic mechanical properties in a wide temperature range, which is of great significance for the reliability in the actual application environment. Especially under the action of cyclic thermal stress, the modified interfacial 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, it is fully confirmed that the present invention has significant advantages in optical properties, thermal stability, interfacial structure, and environmental durability. The realization of these excellent properties stems from multiple innovations in formulation design and process optimization, and significant synergistic effects are formed among various technical features. In particular, the construction of the multi-level scattering structure, the innovation of the interfacial modification technology, and the optimization of the multiple stabilizer system jointly achieve a comprehensive improvement in performance, providing a new technical solution for the development of high-performance quantum dot diffusion plates.

[0164] The above are only the embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. High temperature resistant quantum dot diffusion plate, characterized in that: By weight, it includes the following components: Diffusion particles 90-99.9 parts; Quantum dots 0.1-10 parts; Stabilizer 0.1-5 parts; Wherein, the stabilizer includes at least one of a nitroxide free radical light stabilizer, a hindered amine light stabilizer and a hydroquinone light stabilizer.

2. The high temperature resistant quantum dot diffusion plate according to claim 1, characterized in that: The diffusion particles include: Main part: 85-95 parts of surface modified silica microspheres; Diffusion-aiding components: 2-5 parts of nano-alumina and 3-10 parts of nano-zirconia; The particle size D50 of the surface modified silica microspheres is 1.5-2.5 μm, and the sphericity is not less than 0.

95.

3. The high temperature resistant quantum dot diffusion plate according to claim 2, characterized in that: The surface-modified silica microspheres are modified using the following coupling agent: γ-aminopropyltriethoxysilane 1.0-2.0wt%; γ-methacryloxypropyltrimethoxysilane 0.3-0.8wt%; The wt% is the mass percentage relative to the silica microspheres.

4. The high temperature resistant quantum dot diffusion plate according to claim 1, characterized in that: The quantum dots are CdSe / ZnS core-shell structure quantum dots, including: CdSe core, particle size 3-4nm; ZnS shell, thickness 1.0-1.4nm; Surface ligands: oleylamine 70-80wt% and octadecene 20-30wt%.

5. The high temperature resistant quantum dot diffusion plate according to claim 1, characterized in that: The stabilizer comprises: a nitroxide free radical light stabilizer: 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxy free radical, 0.05-2 parts; a hindered amine light stabilizer: Tinuvin 770 60-70wt% and Chimassorb 944 30-40wt%, a total of 0.03-2 parts; and a hydroquinone light stabilizer: Irganox 1010, 0.02-1 parts.

6. A method for preparing a high temperature resistant quantum dot diffusion plate according to any one of claims 1 to 5, characterized in that: The steps include: Step (1): surface modification of diffusion particles; Step (2): quantum dot surface treatment; Step (3): preparing a stabilizer; Step (4): Preparation of composite materials.

7. The preparation method according to claim 6, characterized in that: The step (1) comprises: (1a) drying the silica microspheres in vacuum at 80±2°C for 12±0.5h; (1b) Prepare coupling agent solution and hydrolyze at 30±2℃ for 2h; (1c) performing surface modification reaction at a temperature of 30±2°C and a time of 3±0.2h; (1d) Centrifuge, wash with ethanol three times, and vacuum dry at 60±2℃ for 8±0.5h.

8. The preparation method according to claim 6, characterized in that: The step (2) comprises: (2a) CdSe / ZnS quantum dots were dispersed in n-hexane at a concentration of 1.0±0.1wt%; (2b) Surface ligand exchange at 45 ± 2 °C for 4 ± 0.2 h; (2c) Centrifuge at 10,000 rpm for 10 min and wash three times with methanol.

9. The preparation method according to claim 6, characterized in that: The step (3) comprises: (3a) preparing solutions of three stabilizers respectively; (3b) Mix according to the ratio at 25±2°C, stirring speed 200±20 rpm, time 60±5 min; (3c) Ultrasonic dispersion, power 150 W, time 20 ± 2 min.

10. The preparation method according to claim 6, characterized in that: The step (4) comprises: (4a) adding the modified diffusion particles into the epoxy resin in 3-5 portions at a temperature of 40±2°C and a stirring speed of 300±20 rpm; (4b) adding quantum dot solution dropwise at a rate of 2±0.2 mL / min and a temperature of 35±2°C; (4c) Add stabilizer solution, temperature 30±2°C, stirring speed 200±20rpm; (4d) vacuum degassing, pressure not greater than 0.05 MPa, time 20 ± 2 min; (4e) adding a curing agent, with an equivalent ratio of 1.0-1.1; (4f) Curing is carried out, including two stages of keeping warm at 80±2℃ for 2h and keeping warm at 120±2℃ for 4h.

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