Light-emitting diode packaging material and preparation method thereof

Abstract

The invention discloses a light-emitting diode packaging material and a preparation method thereof, and relates to the technical field of light-emitting diodes. The method comprises the following steps: adding 4, 4 '-diaminodiphenyl ether into pyromellitic dianhydride for condensation polymerization to obtain a polyamic acid solution, and adding zinc borate nanowires and aluminum nitride powder to prepare an inorganic skeleton enhanced polyamic acid suspension; the preparation method comprises the following steps: reacting zirconium hydroxide sol with an aluminum sec-butoxide solution, and carrying out hydrothermal reaction and high-temperature calcination to obtain ZrO2at-alpha-Al2O3 core-shell particles; the preparation method comprises the following steps: pre-polymerizing 4, 4 '-diphenylmethane bismaleimide and bisphenol A cyanate ester to obtain a prepolymer; the preparation method comprises the following steps: mixing bisphenol A type epoxy resin, inorganic skeleton reinforced polyamide acid suspension, ZrO2at-alpha-Al2O3 core-shell particles and a prepolymer under vacuum, defoaming, injecting into a mold, heating, curing, cooling and demolding to obtain the product. Through the synergistic effect of triple modification, the high temperature resistance and lasting thermal stability of the packaging material are improved, and the packaging material is suitable for the field of light emitting diode packaging with high temperature resistance requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of light-emitting diodes, and in particular to a light-emitting diode packaging material and a preparation method thereof. Background Art

[0002] As a highly efficient, energy-saving, and environmentally friendly light source, light-emitting diodes (LEDs) have been widely used in numerous fields, including lighting, displays, automobiles, and communications. With the continuous advancement of technology and the continued growth of market demand, the requirements for LED performance and reliability are also increasing. Among them, the packaging material largely determines the performance of LEDs.

[0003] Currently, epoxy resin is a widely used encapsulation material for LED packaging. Its excellent mechanical strength and chemical resistance effectively protect LED chips from environmental influences such as dust and moisture, ensuring stable chip operation. Epoxy resin also offers excellent electrical insulation properties, which plays a key role in preventing safety issues such as leakage during LED operation, ensuring user safety and proper operation of the device. Furthermore, its relatively low cost effectively controls costs in large-scale production, making LED products more price-competitive in the market, a key factor contributing to its widespread use. These advantages have made epoxy resin the mainstream choice for LED packaging in general lighting fixtures.

[0004] However, epoxy resin also has some significant drawbacks, most notably its poor high-temperature resistance. When LEDs operate, especially high-power LEDs, they generate significant heat, causing the ambient temperature of the encapsulation material to rise. In high-temperature environments, epoxy resin performance deteriorates. For one thing, it is prone to yellowing, which seriously affects the LED's luminous efficiency and color consistency. Yellowing of the epoxy resin can give the originally emitted white light a yellowish tint, significantly reducing the lighting effect. For color-critical applications such as display screens, this loss of color consistency can lead to color shifts in the display, impacting visual quality. Furthermore, high temperatures can degrade the epoxy resin's mechanical properties, such as reduced hardness and toughness, thereby weakening its protective effect on the chip. Repeated thermal stress can cause epoxy resin to crack, exposing the chip to the external environment, significantly shortening the LED's lifespan and increasing maintenance costs and replacement frequency. In high-power LED applications such as automotive headlights, where operating temperatures are high, these shortcomings of epoxy resin encapsulation materials are magnified, limiting further development and performance improvements of LEDs in these areas. Summary of the Invention

[0005] The present invention aims to provide a light-emitting diode packaging material and a method for preparing the same, in order to address the technical problem of poor high-temperature resistance of epoxy resin packaging materials for light-emitting diodes mentioned in the background art. The light-emitting diodes prepared by the present invention have excellent high-temperature resistance and long-term thermal stability.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a light-emitting diode packaging material comprises the following steps:

[0008] a) dissolving 4,4'-diaminodiphenyl ether in N-methylpyrrolidone, adding pyromellitic dianhydride under nitrogen protection to carry out polycondensation reaction to obtain a polyamic acid solution, and then adding zinc borate nanowires and aluminum nitride powder to the solution and ultrasonically dispersing the solution to obtain an inorganic skeleton reinforced polyamic acid suspension;

[0009] b) adjusting the pH of a zirconium oxychloride aqueous solution with ammonia to generate a zirconium hydroxide sol, which is then dispersed in diethylene glycol after aging, separation, and washing. A sec-butoxide aluminum solution is then added dropwise, followed by a hydrothermal reaction and high-temperature calcination to obtain ZrO2@α-Al2O3 core-shell particles;

[0010] c) dissolving 4,4'-diphenylmethane bismaleimide and bisphenol A cyanate in tetrahydrofuran, and performing a prepolymerization reaction in the presence of a 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator to obtain a prepolymer;

[0011] d) mixing bisphenol A epoxy resin, inorganic skeleton reinforced polyamic acid suspension, ZrO2@α-Al2O3 core-shell particles, prepolymer, and 2-hydroxy-4-methoxybenzophenone under vacuum conditions and degassing, injecting into a mold, curing by heating, and demolding by natural cooling to obtain the high-temperature resistant light-emitting diode packaging material.

[0012] In the technical solution of the present invention, the high temperature resistance of epoxy resin is mainly improved from three aspects. First, the heat resistance of light-emitting diode packaging materials is preliminarily improved by constructing an inorganic reinforced skeleton. The core is to use a polyamic acid solution in the high temperature curing stage. A dehydration ring-closure reaction occurs in the polyamic acid molecule. The originally linear molecular chain is gradually converted into a rigid aromatic heterocyclic structure through this reaction, and finally forms a stable polyimide network. The bond energy of the benzimidazole ring conjugated system in the molecular chain is much higher than that of conventional polymer chains, providing a solid heat-resistant foundation for the material. The introduced zinc borate nanowires are not simply mixed, but are tightly combined with the polyimide chain through coordination bonds, similar to the steel bars in reinforced concrete structures, interspersed in the polyimide network, and can maintain structural stability even in high temperature environments, thereby enhancing the thermal deformation resistance of the overall material. The aluminum nitride powder added at the same time is evenly dispersed inside the material, interconnected to build a three-dimensional heat conduction network, which can quickly transfer and diffuse the locally generated heat to avoid heat accumulation to form high-temperature hot spots. Through the above effects, not only the glass transition temperature of the material is increased, but also the thermal expansion coefficient is reduced, which fundamentally inhibits the relaxation of molecular segments due to heat at high temperatures, as well as the failure problem caused by the volume expansion of the material due to temperature changes. Secondly, the dual protection mechanism of ZrO2@α-Al2O3 core-shell particles is used to block the thermal degradation path of the material, such as Figure 1 This is an SEM image of the ZrO2@α-Al2O3 core-shell particles prepared in the present invention. The core-shell particles are composed of a zirconium oxide core and an aluminum oxide shell. Under high temperature conditions, the zirconium oxide core undergoes a martensitic phase transformation, transforming from a tetragonal phase to a monoclinic phase. This phase transformation process produces a certain volume expansion, which can absorb the crack propagation energy generated by thermal stress within the material and prevent further extension of the crack. The aluminum oxide shell acts as a thermal barrier layer, reducing the transfer of heat into the interior of the material through the phonon scattering effect of thermal radiation, thereby blocking some thermal radiation. The interface of the core-shell particles is not a simple contact, but forms a stable Zr-O-Al chemical bond, ensuring the stability of the core-shell structure at high temperatures. Finally, a cross-linked network is reconstructed by copolymerizing bismaleimide with cyanate to form a high-temperature resistant trapezoidal fused ring structure, providing core heat-resistant support for the packaging material. In the prepolymer generated by the prepolymerization reaction, not only rigid structures such as triazine rings and imide rings are contained, but also the residual cyanate group can react with the epoxy group in the epoxy resin to generate an oxazolidone structure, significantly enhancing the bonding strength between the cross-linked network and the epoxy resin matrix. In addition, the cross-linked network interpenetrates with the polyimide chain to form an interpenetrating structure in the high-temperature deep curing stage, thereby significantly increasing the thermal decomposition temperature of the material. The present invention significantly improves the high-temperature resistance of the light-emitting diode epoxy resin through the above-mentioned synergistic effect.

[0013] Preferably, in step a), the mass ratio of 4,4'-diaminodiphenyl ether to pyromellitic dianhydride is 2:1.5-2.

[0014] Preferably, in step a), the mass ratio of the zinc borate nanowires to the aluminum nitride powder is 3:1-3.

[0015] Preferably, in step b), the calcination temperature is 1150-1200° C., and the calcination time is 2-3 hours.

[0016] Preferably, in step c), the mass ratio of 4,4'-diphenylmethane bismaleimide to bisphenol A cyanate is 10:4-7.

[0017] Preferably, in step c), the amount of 2-phenyl-4,6-bis(dimethylamino)-s-triazine added is 0.5-0.8 wt % of the mass of 4,4'-diphenylmethanebismaleimide.

[0018] Preferably, in step d), the ZrO2@α-Al2O3 core-shell particles are subjected to surface grafting modification treatment with phenyltrimethoxysilane.

[0019] To further improve the high-temperature resistance of the packaging material, the present invention modifies the ZrO2@α-Al2O3 core-shell particles. By grafting phenyltrimethoxysilane on the surface of the ZrO2@α-Al2O3 core-shell particles, the triazine ring in the prepolymer contains nucleophilic tertiary nitrogen atoms. These tertiary nitrogen atoms will actively attack the methoxy groups remaining in the silane on the surface of the core-shell particles, triggering a nucleophilic substitution reaction. The oxygen atoms in the methoxy groups are replaced by tertiary nitrogen atoms, and ultimately a stable Si-OCN bonded structure is formed through intramolecular rearrangement. This Si-NC bond has excellent high-temperature resistance. At the same time, the modified core-shell particles are firmly connected to the prepolymer cross-linked network, so that the core-shell particles are more stably embedded in the cross-linked system, avoiding performance degradation caused by interface separation at high temperatures. This, in conjunction with the thermal protection effect of the core-shell structure and the high-temperature resistance of the cross-linked network, further improves the high-temperature resistance of the packaging material.

[0020] Preferably, during the modification process of the ZrO2@α-Al2O3 core-shell particles, the mass ratio of ZrO2@α-Al2O3 core-shell particles to phenyltrimethoxysilane is 10:0.1-0.3.

[0021] Preferably, the mass ratio of the bisphenol A epoxy resin to the modified ZrO2@α-Al2O3 core-shell particles is 10:2-3.

[0022] A light-emitting diode packaging material is prepared by the above method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The inorganic reinforced skeleton forms a rigid polyimide network, the core-shell particles provide thermal protection and interface stable bonding and cross-linking network reconstruction to form a trapezoidal fused ring energy barrier, which synergistically solves the problem of poor temperature resistance of traditional epoxy resins.

[0025] 2. The modified core-shell particles are firmly connected to the cross-linked network through Si-OCN bonds, effectively avoiding interface separation and performance degradation at high temperatures and ensuring long-term thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the SEM image of the ZrO2@α-Al2O3 core-shell particles prepared in the present invention. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a light-emitting diode packaging material comprises the following steps:

[0030] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir under nitrogen protection until completely dissolved. Weigh 9.5g of pyromellitic dianhydride and slowly add the above solution in 5 batches under a 10°C ice bath, with an interval of 10 minutes between each batch. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continue mechanical stirring for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 2.5g of aluminum nitride powder, turn on a 400W ultrasonic crusher to disperse for 30 minutes, and obtain a uniform inorganic skeleton reinforced polyamic acid suspension. Seal and set aside.

[0031] Step 2: 500 mL of a 0.1 mol / L zirconium oxychloride aqueous solution was placed in a beaker. Under magnetic stirring, the pH of the solution was adjusted to 9.5 with aqueous ammonia to produce a milky white zirconium hydroxide sol. The sol was allowed to stand for 24 hours and then centrifuged at 12,000 rpm for 15 minutes. The supernatant was discarded, and the precipitate was washed three times with anhydrous ethanol and dispersed in 200 mL of diethylene glycol to obtain a dispersion. Separately, 300 mL of a 0.05 mol / L aluminum sec-butoxide solution was added dropwise at a rate of 2 drops / second in an 80°C water bath. After completion of the addition, the solution was transferred to an autoclave and hydrothermally reacted at 180°C for 12 hours. The reaction product was dried and calcined in a muffle furnace at 1180°C for 2.5 hours. After natural cooling, ZrO2@α-Al2O3 core-shell particles were obtained.

[0032] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 12g of bisphenol A cyanate, dissolve them in 250mL of tetrahydrofuran solvent, and stir until completely dissolved. After replacing the air in the system with nitrogen, add 0.15g of 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator. Heat to 75°C in an oil bath and mechanically stir at 300 rpm to carry out a prepolymerization reaction. Continue stirring for 60 minutes before stopping the reaction to obtain a prepolymer, which is then sealed and stored in a dark place.

[0033] Step 4: Weigh 10 g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.25 g of phenyltrimethoxysilane into 300 mL of toluene solvent. Then, add 10 mL of deionized water and stir thoroughly. Reflux at 110°C for 3 hours to perform surface grafting modification. After the reaction, filter the product, wash twice with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 4 hours to obtain the modified ZrO2@α-Al2O3 core-shell particles, which are then set aside.

[0034] 60g of bisphenol A epoxy resin was placed in a vacuum stirred autoclave. 100g of an inorganic skeleton-reinforced polyamic acid suspension, 17g of modified ZrO2@α-Al2O3 core-shell particles, 15g of prepolymer, and 2.0g of 2-hydroxy-4-methoxybenzophenone were added in sequence. Degassing was performed at 500rpm under a vacuum of 0.1MPa for 30 minutes. The mixed adhesive was injected into a mold and cured in a stepwise manner: heating at a rate of 2°C / min to 130°C and holding for 60 minutes; then at a rate of 3°C / min to 180°C and holding for 120 minutes; and finally at a rate of 1°C / min to 200°C and holding for 180 minutes. The mixture was then cooled naturally to room temperature and demolded to obtain a high-temperature-resistant light-emitting diode encapsulation material.

[0035] Example 2

[0036] A method for preparing a light-emitting diode packaging material comprises the following steps:

[0037] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir under nitrogen protection until completely dissolved. Weigh 8g of pyromellitic dianhydride and slowly add the above solution in 5 batches under a 10°C ice bath, with a 10-minute interval between each batch. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continue mechanical stirring for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 1.5g of aluminum nitride powder, turn on a 400W ultrasonic crusher to disperse for 30 minutes, and obtain a uniform inorganic skeleton reinforced polyamic acid suspension. Seal and set aside.

[0038] Step 2: 500 mL of a 0.1 mol / L zirconium oxychloride aqueous solution was placed in a beaker. Under magnetic stirring, the pH of the solution was adjusted to 9.5 with aqueous ammonia to produce a milky white zirconium hydroxide sol. The sol was allowed to stand for 24 hours and then centrifuged at 12,000 rpm for 15 minutes. The supernatant was discarded, and the precipitate was washed three times with anhydrous ethanol and dispersed in 200 mL of diethylene glycol to obtain a dispersion. Separately, 300 mL of a 0.05 mol / L aluminum sec-butoxide solution was added dropwise at a rate of 2 drops / second in an 80°C water bath. After completion of the addition, the solution was transferred to an autoclave and hydrothermally reacted at 180°C for 12 hours. The reaction product was dried and calcined in a muffle furnace at 1180°C for 2.5 hours. After natural cooling, ZrO2@α-Al2O3 core-shell particles were obtained.

[0039] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 9g of bisphenol A cyanate, dissolve them in 250mL of tetrahydrofuran solvent, and stir until completely dissolved. After replacing the air in the system with nitrogen, add 0.12g of 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator. Heat to 75°C in an oil bath and mechanically stir at 300 rpm to carry out a prepolymerization reaction. Continue stirring for 60 minutes before stopping the reaction to obtain a prepolymer, which is then sealed and stored in a dark place.

[0040] Step 4: Weigh 10 g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.15 g of phenyltrimethoxysilane into 300 mL of toluene solvent. Then, add 10 mL of deionized water and stir thoroughly. Reflux at 110°C for 3 hours to perform surface grafting modification. After the reaction, filter the product, wash twice with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 4 hours to obtain the modified ZrO2@α-Al2O3 core-shell particles, which are then set aside.

[0041] 60g of bisphenol A epoxy resin was placed in a vacuum stirred autoclave. 100g of an inorganic skeleton-reinforced polyamic acid suspension, 14g of modified ZrO2@α-Al2O3 core-shell particles, 15g of prepolymer, and 2.0g of 2-hydroxy-4-methoxybenzophenone were added in that order. Degassing was performed at 500rpm under a vacuum of 0.1MPa for 30 minutes. The mixed adhesive was injected into a mold and cured in a stepwise manner: heating at a rate of 2°C / min to 130°C and holding for 60 minutes; then at a rate of 3°C / min to 180°C and holding for 120 minutes; and finally at a rate of 1°C / min to 200°C and holding for 180 minutes. The mixture was then naturally cooled to room temperature and demolded to obtain a high-temperature-resistant light-emitting diode encapsulation material.

[0042] Example 3

[0043] A method for preparing a light-emitting diode packaging material comprises the following steps:

[0044] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir under nitrogen protection until completely dissolved. Weigh 8.5g of pyromellitic dianhydride and slowly add the above solution in 5 batches in a 10°C ice bath environment, with a 10-minute interval between each batch. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continue mechanical stirring for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 2g of aluminum nitride powder, turn on a 400W ultrasonic crusher to disperse for 30 minutes, and obtain a uniform inorganic skeleton reinforced polyamic acid suspension. Seal and set aside.

[0045] Step 2: 500 mL of a 0.1 mol / L zirconium oxychloride aqueous solution was placed in a beaker. Under magnetic stirring, the pH of the solution was adjusted to 9.5 with aqueous ammonia to produce a milky white zirconium hydroxide sol. The sol was allowed to stand for 24 hours and then centrifuged at 12,000 rpm for 15 minutes. The supernatant was discarded, and the precipitate was washed three times with anhydrous ethanol and dispersed in 200 mL of diethylene glycol to obtain a dispersion. Separately, 300 mL of a 0.05 mol / L aluminum sec-butoxide solution was added dropwise at a rate of 2 drops / second in an 80°C water bath. After completion of the addition, the solution was transferred to an autoclave and hydrothermally reacted at 180°C for 12 hours. The reaction product was dried and calcined in a muffle furnace at 1180°C for 2.5 hours. After natural cooling, ZrO2@α-Al2O3 core-shell particles were obtained.

[0046] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 11g of bisphenol A cyanate, dissolve them in 250mL of tetrahydrofuran solvent, and stir until completely dissolved. After replacing the air in the system with nitrogen, add 0.14g of 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator. Heat to 75°C in an oil bath and mechanically stir at 300 rpm to carry out a prepolymerization reaction. Continue stirring for 60 minutes before stopping the reaction to obtain a prepolymer, which is then sealed and stored in a dark place.

[0047] Step 4: Weigh 10 g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.2 g of phenyltrimethoxysilane into 300 mL of toluene solvent. Then, add 10 mL of deionized water and stir thoroughly. Reflux at 110°C for 3 hours to perform surface grafting modification. After the reaction, filter the product, wash twice with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 4 hours to obtain the modified ZrO2@α-Al2O3 core-shell particles, which are then set aside.

[0048] 60g of bisphenol A epoxy resin was placed in a vacuum stirred autoclave. 100g of an inorganic skeleton-reinforced polyamic acid suspension, 15g of modified ZrO2@α-Al2O3 core-shell particles, 15g of prepolymer, and 2.0g of 2-hydroxy-4-methoxybenzophenone were added in that order. Degassing was performed at 500rpm under a vacuum of 0.1MPa for 30 minutes. The mixed adhesive was injected into a mold and cured in a stepwise manner: heating at a rate of 2°C / min to 130°C and holding for 60 minutes; then at a rate of 3°C / min to 180°C and holding for 120 minutes; and finally at a rate of 1°C / min to 200°C and holding for 180 minutes. The mixture was then naturally cooled to room temperature and demolded to obtain a high-temperature-resistant light-emitting diode encapsulation material.

[0049] Example 4

[0050] A method for preparing a light-emitting diode packaging material comprises the following steps:

[0051] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir under nitrogen protection until completely dissolved. Weigh 10g of pyromellitic dianhydride and slowly add the above solution in 5 batches under a 10°C ice bath, with a 10-minute interval between each batch. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continue mechanical stirring for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 3g of aluminum nitride powder, turn on a 400W ultrasonic crusher to disperse for 30 minutes, and obtain a uniform inorganic skeleton reinforced polyamic acid suspension. Seal and set aside.

[0052] Step 2: 500 mL of a 0.1 mol / L zirconium oxychloride aqueous solution was placed in a beaker. Under magnetic stirring, the pH of the solution was adjusted to 9.5 with aqueous ammonia to produce a milky white zirconium hydroxide sol. The sol was allowed to stand for 24 hours and then centrifuged at 12,000 rpm for 15 minutes. The supernatant was discarded, and the precipitate was washed three times with anhydrous ethanol and dispersed in 200 mL of diethylene glycol to obtain a dispersion. Separately, 300 mL of a 0.05 mol / L aluminum sec-butoxide solution was added dropwise at a rate of 2 drops / second in an 80°C water bath. After completion of the addition, the solution was transferred to an autoclave and hydrothermally reacted at 180°C for 12 hours. The reaction product was dried and calcined in a muffle furnace at 1200°C for 3 hours. After natural cooling, ZrO2@α-Al2O3 core-shell particles were obtained.

[0053] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 14g of bisphenol A cyanate, dissolve them in 250mL of tetrahydrofuran solvent, and stir until completely dissolved. After replacing the air in the system with nitrogen, add 0.16g of 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator. Heat to 75°C in an oil bath and mechanically stir at 300 rpm to carry out a prepolymerization reaction. Continue stirring for 60 minutes before stopping the reaction to obtain a prepolymer, which is then sealed and stored in a dark place.

[0054] Step 4: Weigh 10 g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.3 g of phenyltrimethoxysilane into 300 mL of toluene solvent. Then, add 10 mL of deionized water and stir thoroughly. Reflux at 110°C for 3 hours to perform surface grafting modification. After the reaction, filter the product, wash twice with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 4 hours to obtain the modified ZrO2@α-Al2O3 core-shell particles, which are then set aside.

[0055] 60g of bisphenol A epoxy resin was placed in a vacuum stirred autoclave. 100g of an inorganic skeleton-reinforced polyamic acid suspension, 18g of modified ZrO2@α-Al2O3 core-shell particles, 15g of prepolymer, and 2.0g of 2-hydroxy-4-methoxybenzophenone were added in sequence. Degassing was performed at 500rpm under a vacuum of 0.1MPa for 30 minutes. The mixed adhesive was injected into a mold and cured in a stepwise manner: heating at a rate of 2°C / min to 130°C and holding for 60 minutes; then at a rate of 3°C / min to 180°C and holding for 120 minutes; and finally at a rate of 1°C / min to 200°C and holding for 180 minutes. The mixture was then naturally cooled to room temperature and demolded to obtain a high-temperature-resistant light-emitting diode encapsulation material.

[0056] Example 5

[0057] A method for preparing a light-emitting diode packaging material comprises the following steps:

[0058] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir under nitrogen protection until completely dissolved. Weigh 7.5g of pyromellitic dianhydride and slowly add the above solution in 5 batches under a 10°C ice bath, with a 10-minute interval between each batch. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continue mechanical stirring for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 1g of aluminum nitride powder, turn on a 400W ultrasonic crusher to disperse for 30 minutes, and obtain a uniform inorganic skeleton reinforced polyamic acid suspension. Seal and set aside.

[0059] Step 2: 500 mL of a 0.1 mol / L zirconium oxychloride aqueous solution was placed in a beaker. Under magnetic stirring, the pH of the solution was adjusted to 9.5 with aqueous ammonia to produce a milky white zirconium hydroxide sol. The sol was allowed to stand for 24 hours and then centrifuged at 12,000 rpm for 15 minutes. The supernatant was discarded, and the precipitate was washed three times with anhydrous ethanol and dispersed in 200 mL of diethylene glycol to obtain a dispersion. Separately, 300 mL of a 0.05 mol / L aluminum sec-butoxide solution was added dropwise at a rate of 2 drops / second in an 80°C water bath. After completion of the addition, the solution was transferred to an autoclave and hydrothermally reacted at 180°C for 12 hours. The reaction product was dried and calcined in a muffle furnace at 1150°C for 2 hours. After natural cooling, ZrO2@α-Al2O3 core-shell particles were obtained.

[0060] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 8g of bisphenol A cyanate, dissolve them in 250mL of tetrahydrofuran solvent, and stir until completely dissolved. After replacing the air in the system with nitrogen, add 0.10g of 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator. Heat to 75°C in an oil bath and mechanically stir at 300 rpm to carry out a prepolymerization reaction. Continue stirring for 60 minutes before stopping the reaction to obtain a prepolymer, which is then sealed and stored in a dark place.

[0061] Step 4: Weigh 10 g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.1 g of phenyltrimethoxysilane into 300 mL of toluene solvent. Then, add 10 mL of deionized water and stir thoroughly. Reflux at 110°C for 3 hours to perform surface grafting modification. After the reaction, filter the product, wash twice with anhydrous ethanol, and dry it in a vacuum oven at 60°C for 4 hours to obtain the modified ZrO2@α-Al2O3 core-shell particles, which are then set aside.

[0062] 60g of bisphenol A epoxy resin was placed in a vacuum stirred autoclave. 100g of an inorganic skeleton-reinforced polyamic acid suspension, 12g of modified ZrO2@α-Al2O3 core-shell particles, 15g of prepolymer, and 2.0g of 2-hydroxy-4-methoxybenzophenone were added in that order. Degassing was performed at 500rpm under a vacuum of 0.1MPa for 30 minutes. The mixed adhesive was injected into a mold and cured in a stepwise manner: heating at a rate of 2°C / min to 130°C and holding for 60 minutes; then at a rate of 3°C / min to 180°C and holding for 120 minutes; and finally at a rate of 1°C / min to 200°C and holding for 180 minutes. The mixture was then naturally cooled to room temperature and demolded to obtain a high-temperature-resistant light-emitting diode encapsulation material.

[0063] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that step 1 is omitted in the preparation process of the light-emitting diode packaging material, and the inorganic skeleton-reinforced polyamic acid suspension is not added in step 4.

[0064] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that step 2 is omitted in the preparation process of the light-emitting diode packaging material, and modified ZrO2@α-Al2O3 core-shell particles are not added in step 4.

[0065] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the ZrO2@α-Al2O3 core-shell particles are not modified in step 4 during the preparation of the light-emitting diode packaging material.

[0066] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that step 3 is omitted in the preparation process of the light-emitting diode packaging material, and no prepolymer is added in step 4.

[0067] Performance testing:

[0068] 1. Glass transition temperature test: Differential scanning calorimetry (DSC) was used in accordance with ASTM D3418. Approximately 10 mg of sample was heated from room temperature to 300°C at a rate of 10°C / min under a nitrogen atmosphere. The glass transition temperature was determined by recording the inflection point of the baseline shift in the heat flow curve. The test results are shown in Table 1.

[0069] 2. Thermal Decomposition Temperature Test: A thermogravimetric analyzer (TGA) was used according to ASTM E1131. A 10 mg sample was heated from room temperature to 600°C in a nitrogen atmosphere at a rate of 10°C / min. The thermal decomposition temperature was determined when the sample mass loss reached 5%. The test results are shown in Table 1.

[0070] 3. High-Temperature Aging Yellowing Index Test: Samples were tested using a colorimeter according to ASTM D1925. The samples were aged in a 250°C oven for 1000 hours. After cooling to room temperature, the yellowing index (YI) of the samples was measured. A lower YI value indicates better yellowing resistance. See Table 1 for test results.

[0071] 4. High-Temperature Aging Hardness Retention Test: The initial hardness of the sample was measured using a Shore D durometer according to ASTM D2240. The sample was then aged in a 250°C oven for 1000 hours. After cooling, the hardness was re-measured. Hardness retention = (hardness after aging / initial hardness) × 100%. A higher value indicates better high-temperature mechanical stability. See Table 1 for test results.

[0072] Table 1:

[0073] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a light-emitting diode packaging material, characterized in that: The following steps are involved: a) dissolving 4,4'-diaminodiphenyl ether in N-methylpyrrolidone, adding pyromellitic dianhydride under nitrogen protection to carry out polycondensation reaction to obtain a polyamic acid solution, and then adding zinc borate nanowires and aluminum nitride powder to the solution and ultrasonically dispersing the solution to obtain an inorganic skeleton reinforced polyamic acid suspension; b) adjusting the pH of a zirconium oxychloride aqueous solution with ammonia to generate a zirconium hydroxide sol, which is then dispersed in diethylene glycol after aging, separation, and washing. A sec-butoxide aluminum solution is then added dropwise, followed by a hydrothermal reaction and high-temperature calcination to obtain ZrO2@α-Al2O3 core-shell particles; c) dissolving 4,4'-diphenylmethane bismaleimide and bisphenol A cyanate in tetrahydrofuran, and performing a prepolymerization reaction in the presence of a 2-phenyl-4,6-bis(dimethylamino)-s-triazine accelerator to obtain a prepolymer; d) mixing bisphenol A epoxy resin, inorganic skeleton reinforced polyamic acid suspension, ZrO2@α-Al2O3 core-shell particles, prepolymer, and 2-hydroxy-4-methoxybenzophenone under vacuum conditions and degassing, injecting into a mold, curing by heating, and demolding by natural cooling to obtain the high-temperature resistant light-emitting diode packaging material.

2. The method for preparing a light emitting diode packaging material according to claim 1, wherein: In the step a), the mass ratio of 4,4'-diaminodiphenyl ether to pyromellitic dianhydride is 2:1.5-2.

3. The method for preparing a light emitting diode packaging material according to claim 1, wherein: In the step a), the mass ratio of the zinc borate nanowires to the aluminum nitride powder is 3:1-3.

4. The method for preparing a light emitting diode packaging material according to claim 1, wherein: In the step b), the calcination temperature is 1150-1200° C., and the calcination time is 2-3 hours.

5. The method for preparing a light emitting diode packaging material according to claim 1, characterized in that: In the step c), the mass ratio of 4,4'-diphenylmethane bismaleimide to bisphenol A cyanate is 10:4-7.

6. The method for preparing a light emitting diode packaging material according to claim 1, characterized in that: In the step c), the amount of 2-phenyl-4,6-bis(dimethylamino)-s-triazine added is 0.5-0.8 wt % of the mass of 4,4'-diphenylmethanebismaleimide.

7. The method for preparing a light emitting diode packaging material according to claim 1, characterized in that: In the step d), the ZrO2@α-Al2O3 core-shell particles are subjected to surface grafting modification treatment with phenyltrimethoxysilane.

8. The method for preparing a light emitting diode packaging material according to claim 7, characterized in that: During the modification process of the ZrO2@α-Al2O3 core-shell particles, the mass ratio of the ZrO2@α-Al2O3 core-shell particles to phenyltrimethoxysilane is 10:0.1-0.

3.

9. The method for preparing a light emitting diode packaging material according to claim 7, characterized in that: The mass ratio of the bisphenol A epoxy resin to the modified ZrO2@α-Al2O3 core-shell particles is 10:2-3.

10. A light-emitting diode packaging material, characterized in that: The method is prepared by the method described in any one of claims 1 to 9 above.

Images