A light emitting diode encapsulating material and a method of preparing the same

Abstract

This invention discloses a light-emitting diode (LED) packaging material and its preparation method, relating to the field of LED technology. The method includes the following steps: 4,4'-diaminodiphenyl ether is added to pyromellitic dianhydride for a condensation reaction to obtain a polyamic acid solution; zinc borate nanowires and aluminum nitride powder are added to obtain an inorganic framework-reinforced polyamic acid suspension; zirconium hydroxide sol is reacted with aluminum sec-butoxide solution, followed by hydrothermal reaction and high-temperature calcination to obtain ZrO2@α-Al2O3 core-shell particles; 4,4'-diphenylmethane bismaleimide and bisphenol A cyanate are prepolymerized to obtain a prepolymer; bisphenol A epoxy resin, the inorganic framework-reinforced polyamic acid suspension, ZrO2@α-Al2O3 core-shell particles, and the prepolymer are mixed and degassed under vacuum, injected into a mold, cured by heating, and then demolded to obtain the product. This invention, through a triple modification synergistic effect, improves the high-temperature resistance and long-term thermal stability of the packaging material, making it suitable for LED packaging applications with high temperature resistance requirements.

Description

Technical Field

[0001] This invention relates to the field of light-emitting diode technology, specifically to a light-emitting diode packaging material and its preparation method. Background Technology

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

[0003] Currently, epoxy resin is a widely used encapsulation material in LED packaging. It possesses good mechanical strength and chemical resistance, effectively protecting LED chips from external environmental influences such as dust and moisture, ensuring stable chip operation. Simultaneously, epoxy resin also exhibits excellent electrical insulation properties, playing a crucial role in preventing safety issues such as leakage during LED operation, thus ensuring user safety and the normal operation of equipment. Furthermore, its relatively low cost allows for effective cost control in large-scale production, making LED products more price-competitive in the market, which is one of the important reasons for its widespread application. In LED packaging for general lighting fixtures, epoxy resin has become the mainstream choice due to these advantages.

[0004] However, epoxy resin also has some significant drawbacks, the most prominent being its poor high-temperature resistance. When LEDs are operating, especially high-power LEDs, they generate a large amount of heat, causing the ambient temperature of the encapsulation material to rise. Under high temperatures, the performance of epoxy resin deteriorates. On one hand, it is prone to yellowing, which severely affects the luminous efficiency and color consistency of the LED. The originally emitted white light may take on a yellowish tint due to the yellowing of the epoxy resin, significantly reducing the lighting effect. For applications with high color requirements, such as displays, the disruption of color consistency can lead to color differences in the displayed image, affecting the visual experience. On the other hand, high temperatures can also cause a decrease in the mechanical properties of epoxy resin, such as reduced hardness and toughness, thus weakening its protective effect on the chip. Under repeated thermal stress, epoxy resin may crack, exposing the chip directly to the external environment, greatly shortening the LED's lifespan and increasing maintenance costs and replacement frequency. In high-power LED applications such as automotive headlights, the high operating temperatures amplify these drawbacks of epoxy resin encapsulation materials, limiting further development and performance improvement of LEDs in these fields. Summary of the Invention

[0005] The purpose of this invention is to provide a light-emitting diode (LED) encapsulation material and its preparation method, thereby solving the technical problem of poor high-temperature resistance of epoxy resin encapsulation materials for LEDs mentioned in the background art. The LED prepared by this invention exhibits excellent high-temperature resistance and long-term thermal stability.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a light-emitting diode (LED) packaging material includes the following steps:

[0008] a) Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone, and under nitrogen protection, add pyromellitic dianhydride to carry out a polycondensation reaction to obtain a polyamic acid solution. Then add zinc borate nanowires and aluminum nitride powder to the solution and disperse them by ultrasonication to obtain an inorganic skeleton-reinforced polyamic acid suspension.

[0009] b) The pH of the zirconium oxychloride aqueous solution was adjusted with ammonia to generate zirconium hydroxide sol. After aging, separation and washing, it was dispersed in diethylene glycol. Then, aluminum sec-butoxide solution was added dropwise. After hydrothermal reaction and high-temperature calcination, ZrO2@α-Al2O3 core-shell particles were obtained.

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

[0011] d) Bisphenol A type epoxy resin, inorganic skeleton-reinforced polyamic acid suspension, ZrO2@α-Al2O3 core-shell particles, prepolymer and 2-hydroxy-4-methoxybenzophenone are mixed evenly under vacuum and degassed. After being injected into a mold, the mixture is sequentially heated and cured, and then naturally cooled and demolded to obtain the high-temperature resistant light-emitting diode encapsulation material.

[0012] In this invention, the high-temperature resistance of epoxy resin is improved synergistically from three aspects. First, the heat resistance of the LED encapsulation material is initially enhanced by constructing an inorganic reinforcing framework. The core of this approach is to utilize the dehydration and ring-closing reaction within the polyamic acid molecule during the high-temperature curing stage. The originally linear molecular chain gradually transforms into a rigid aromatic heterocyclic structure through this reaction, ultimately forming a stable polyimide network. The benzimidazole ring conjugated system in the molecular chain has a bond energy far higher than that of conventional polymer chains, providing a solid foundation for the material's heat resistance. The introduced zinc borate nanowires are not simply mixed in; instead, they are tightly bonded to the polyimide chain through coordination bonds, similar to the reinforcing bars in reinforced concrete, interwoven within the polyimide network. This ensures structural stability even at high temperatures, enhancing the overall material's resistance to thermal deformation. Simultaneously, the added aluminum nitride powder is uniformly dispersed within the material, interconnecting to construct a three-dimensional heat conduction network. This network rapidly transfers and diffuses locally generated heat, preventing heat accumulation and the formation of high-temperature hotspots. Through the above-mentioned effects, not only is the glass transition temperature of the material increased, but the coefficient of thermal expansion is also reduced, fundamentally suppressing the relaxation of molecular chain 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 pathway of the material, such as... Figure 1 This is a SEM image of the ZrO2@α-Al2O3 core-shell particles prepared in this invention. The core-shell particles consist of a zirconia core and an alumina shell. Under high-temperature conditions, the zirconia core undergoes a martensitic phase transformation, changing from a tetragonal phase to a monoclinic phase. This phase transformation process generates a certain volume expansion, which absorbs the energy of crack propagation caused by thermal stress within the material, preventing further crack extension. The alumina shell acts as a thermal barrier layer, reducing heat transfer to the interior of the material and blocking some thermal radiation through phonon scattering. The interface between the core and shell particles is not a simple contact but rather forms stable Zr-O-Al chemical bonds, ensuring the stability of the core-shell structure at high temperatures. Finally, the crosslinking network is reconstructed through copolymerization of bismaleimide and cyanate ester to form a high-temperature resistant trapezoidal fused ring structure, providing core temperature-resistant support for the encapsulation material. The prepolymer generated in the prepolymerization reaction not only contains rigid structures such as triazine rings and imide rings, but its residual cyanate ester groups can also react with the epoxy groups in the epoxy resin to form oxazolidinone structures, significantly enhancing the bonding strength between the crosslinking network and the epoxy resin matrix. Furthermore, the crosslinking network interpenetrates with the polyimide chains during the high-temperature deep curing stage to form an interpenetrating structure, thereby significantly increasing the thermal decomposition temperature of the material. Through the above synergistic effects, this invention significantly improves the high-temperature resistance of epoxy resin for light-emitting diodes.

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

[0014] Preferably, in step a), the mass ratio of zinc borate nanowires to aluminum nitride powder is 3:1 to 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 to 7.

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

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

[0019] To further improve the high-temperature resistance of encapsulation materials, this invention modifies ZrO2@α-Al2O3 core-shell particles by grafting phenyltrimethoxysilane onto the surface of the particles. The triazine ring in the prepolymer contains nucleophilic tertiary nitrogen atoms, which actively attack the residual methoxy groups on the silane surface, initiating a nucleophilic substitution reaction. The oxygen atoms in the methoxy groups are replaced by tertiary nitrogen atoms, ultimately forming a stable Si-OCN bond structure through intramolecular rearrangement. This Si-NC bond exhibits excellent high-temperature resistance. Simultaneously, the modified core-shell particles are firmly connected to the prepolymer crosslinking network, allowing the particles to be more stably embedded in the crosslinking system. This prevents performance degradation caused by interfacial separation at high temperatures. The synergistic effect of the core-shell structure's thermal protection and the high-temperature resistance of the crosslinking network further enhances the high-temperature resistance of the encapsulation material.

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

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

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

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. By forming a rigid polyimide network through an inorganic reinforced skeleton, and providing thermal protection and interfacial stability through core-shell particles, the bonding and cross-linking network reconstruction forms 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, which effectively avoids interface separation and performance degradation at high temperatures and ensures long-term thermal stability. Attached Figure Description

[0026] Figure 1 This is a SEM image of the ZrO2@α-Al2O3 core-shell particles prepared in this invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a light-emitting diode (LED) packaging material includes the following steps:

[0030] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir until completely dissolved under continuous nitrogen protection. Weigh 9.5g of pyromellitic dianhydride and slowly add it to the above solution in 5 batches at 10°C ice bath, with each batch spaced 10 minutes apart. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continuously stir mechanically to carry out the polycondensation reaction for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 2.5g of aluminum nitride powder, and disperse using a 400W ultrasonic disruptor for 30 minutes to obtain a uniform inorganic skeleton-reinforced polyamic acid suspension, which is then sealed for later use.

[0031] Step 2: Measure 500 mL of 0.1 mol / L zirconium oxychloride aqueous solution into a beaker. Adjust the pH of the solution to 9.5 with ammonia water while stirring magnetically to generate a milky white zirconium hydroxide sol. After allowing the sol to stand and age for 24 hours, centrifuge at 12000 rpm for 15 minutes, discard the supernatant, wash the precipitate three times with anhydrous ethanol, and then disperse it in 200 mL of diethylene glycol to obtain a dispersion. Take 300 mL of 0.05 mol / L aluminum sec-butoxide solution and add it dropwise to the above dispersion at a rate of 2 drops / second under an 80℃ water bath. After the addition is complete, transfer it to a high-pressure reactor and hydrothermally react at 180℃ for 12 hours. After drying the reaction product, calcine it in a muffle furnace at 1180℃ for 2.5 hours, and then naturally cool to obtain ZrO2@α-Al2O3 core-shell particles.

[0032] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 12g of bisphenol A cyanate, and dissolve them together in 250mL of tetrahydrofuran solvent, stirring until completely dissolved. After purging the system with nitrogen, add 0.15g of 2-phenyl-4,6-bis(dimethylamino)triazine accelerator, heat in an oil bath to 75℃, and mechanically stir at 300rpm to carry out the prepolymerization reaction. After stirring continuously for 60 minutes, stop the reaction to obtain the prepolymer, which should be sealed and stored away from light.

[0033] Step 4: Weigh 10g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.25g of phenyltrimethoxysilane, add them to 300mL of toluene solvent, then add 10mL of deionized water, stir well, and reflux at 110℃ for 3 hours to perform surface grafting modification. After the reaction is complete, filter the product, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60℃ for 4 hours to obtain modified ZrO2@α-Al2O3 core-shell particles for later use.

[0034] 60g of bisphenol A epoxy resin was placed in a vacuum mixing vessel, and 100g of 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 sequentially. The mixture was stirred at 500rpm for 30 minutes under a vacuum of 0.1MPa to remove bubbles. The mixed resin was injected into a mold, and a stepped curing procedure was performed: the temperature was increased to 130℃ at a rate of 2℃ / min and held for 60 minutes; then increased to 180℃ at a rate of 3℃ / min and held for 120 minutes; finally, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 180 minutes. After naturally cooling to room temperature, the material was demolded to obtain a high-temperature resistant LED encapsulation material.

[0035] Example 2

[0036] A method for preparing a light-emitting diode (LED) packaging material includes the following steps:

[0037] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir until completely dissolved under continuous nitrogen protection. Weigh 8g of pyromellitic dianhydride and slowly add it to the above solution in 5 batches at 10°C ice bath, with each batch spaced 10 minutes apart. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continuously stir mechanically to carry out the polycondensation reaction for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 1.5g of aluminum nitride powder, and disperse using a 400W ultrasonic disruptor for 30 minutes to obtain a uniform inorganic skeleton-reinforced polyamic acid suspension, which is then sealed for later use.

[0038] Step 2: Measure 500 mL of 0.1 mol / L zirconium oxychloride aqueous solution into a beaker. Adjust the pH of the solution to 9.5 with ammonia water while stirring magnetically to generate a milky white zirconium hydroxide sol. After allowing the sol to stand and age for 24 hours, centrifuge at 12000 rpm for 15 minutes, discard the supernatant, wash the precipitate three times with anhydrous ethanol, and then disperse it in 200 mL of diethylene glycol to obtain a dispersion. Take 300 mL of 0.05 mol / L aluminum sec-butoxide solution and add it dropwise to the above dispersion at a rate of 2 drops / second under an 80℃ water bath. After the addition is complete, transfer it to a high-pressure reactor and hydrothermally react at 180℃ for 12 hours. After drying the reaction product, calcine it in a muffle furnace at 1180℃ for 2.5 hours, and then naturally cool to obtain ZrO2@α-Al2O3 core-shell particles.

[0039] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 9g of bisphenol A cyanate, and dissolve them together in 250mL of tetrahydrofuran solvent, stirring until completely dissolved. After purging the system with nitrogen, add 0.12g of 2-phenyl-4,6-bis(dimethylamino)triazine accelerator, heat in an oil bath to 75℃, and mechanically stir at 300rpm to carry out the prepolymerization reaction. After stirring continuously for 60 minutes, stop the reaction to obtain the prepolymer, which should be sealed and stored away from light.

[0040] Step 4: Weigh 10g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.15g of phenyltrimethoxysilane, add them to 300mL of toluene solvent, then add 10mL of deionized water, stir well, and reflux at 110℃ for 3 hours to perform surface grafting modification. After the reaction is complete, filter the product, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60℃ for 4 hours to obtain modified ZrO2@α-Al2O3 core-shell particles for later use.

[0041] 60g of bisphenol A epoxy resin was placed in a vacuum mixing vessel, and 100g of 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 sequentially. The mixture was stirred at 500rpm for 30 minutes under a vacuum of 0.1MPa to remove bubbles. The mixed resin was injected into a mold, and a stepped curing procedure was performed: the temperature was increased to 130℃ at a rate of 2℃ / min and held for 60 minutes; then increased to 180℃ at a rate of 3℃ / min and held for 120 minutes; finally, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 180 minutes. After naturally cooling to room temperature, the material was demolded to obtain a high-temperature resistant LED encapsulation material.

[0042] Example 3

[0043] A method for preparing a light-emitting diode (LED) packaging material includes the following steps:

[0044] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir until completely dissolved under continuous nitrogen protection. Weigh 8.5g of pyromellitic dianhydride and slowly add it to the above solution in 5 batches at 10°C ice bath, with each batch spaced 10 minutes apart. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continuously stir mechanically to carry out the polycondensation reaction for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 2g of aluminum nitride powder, and disperse using a 400W ultrasonic disruptor for 30 minutes to obtain a uniform inorganic skeleton-reinforced polyamic acid suspension, which is then sealed for later use.

[0045] Step 2: Measure 500 mL of 0.1 mol / L zirconium oxychloride aqueous solution into a beaker. Adjust the pH of the solution to 9.5 with ammonia water while stirring magnetically to generate a milky white zirconium hydroxide sol. After allowing the sol to stand and age for 24 hours, centrifuge at 12000 rpm for 15 minutes, discard the supernatant, wash the precipitate three times with anhydrous ethanol, and then disperse it in 200 mL of diethylene glycol to obtain a dispersion. Take 300 mL of 0.05 mol / L aluminum sec-butoxide solution and add it dropwise to the above dispersion at a rate of 2 drops / second under an 80℃ water bath. After the addition is complete, transfer it to a high-pressure reactor and hydrothermally react at 180℃ for 12 hours. After drying the reaction product, calcine it in a muffle furnace at 1180℃ for 2.5 hours, and then naturally cool to obtain ZrO2@α-Al2O3 core-shell particles.

[0046] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 11g of bisphenol A cyanate, and dissolve them together in 250mL of tetrahydrofuran solvent, stirring until completely dissolved. After purging the system with nitrogen, add 0.14g of 2-phenyl-4,6-bis(dimethylamino)triazine accelerator, heat in an oil bath to 75℃, and mechanically stir at 300rpm to carry out the prepolymerization reaction. After stirring continuously for 60 minutes, stop the reaction to obtain the prepolymer, which should be sealed and stored away from light.

[0047] Step 4: Weigh 10g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.2g of phenyltrimethoxysilane, add them to 300mL of toluene solvent, then add 10mL of deionized water, stir well, and reflux at 110℃ for 3 hours to perform surface grafting modification. After the reaction is complete, filter the product, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60℃ for 4 hours to obtain modified ZrO2@α-Al2O3 core-shell particles for later use.

[0048] 60g of bisphenol A epoxy resin was placed in a vacuum mixing vessel, and 100g of 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 sequentially. The mixture was stirred at 500rpm for 30 minutes under a vacuum of 0.1MPa to remove bubbles. The mixed resin was injected into a mold, and a stepped curing procedure was performed: the temperature was increased to 130℃ at a rate of 2℃ / min and held for 60 minutes; then increased to 180℃ at a rate of 3℃ / min and held for 120 minutes; finally, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 180 minutes. After naturally cooling to room temperature, the material was demolded to obtain a high-temperature resistant LED encapsulation material.

[0049] Example 4

[0050] A method for preparing a light-emitting diode (LED) packaging material includes the following steps:

[0051] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir until completely dissolved under continuous nitrogen protection. Weigh 10g of pyromellitic dianhydride and slowly add it to the above solution in 5 batches at 10°C ice bath, with each batch spaced 10 minutes apart. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continuously stir mechanically to carry out the polycondensation reaction for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 3g of aluminum nitride powder, and disperse using a 400W ultrasonic disruptor for 30 minutes to obtain a uniform inorganic skeleton-reinforced polyamic acid suspension, which is then sealed for later use.

[0052] Step 2: Measure 500 mL of 0.1 mol / L zirconium oxychloride aqueous solution into a beaker. Adjust the pH of the solution to 9.5 with ammonia water while stirring magnetically to generate a milky white zirconium hydroxide sol. After allowing the sol to stand and age for 24 hours, centrifuge at 12000 rpm for 15 minutes, discard the supernatant, wash the precipitate three times with anhydrous ethanol, and then disperse it in 200 mL of diethylene glycol to obtain a dispersion. Take 300 mL of 0.05 mol / L aluminum sec-butoxide solution and add it dropwise to the above dispersion at a rate of 2 drops / second under an 80℃ water bath. After the addition is complete, transfer it to a high-pressure reactor and hydrothermally react at 180℃ for 12 hours. After drying the reaction product, calcine it in a muffle furnace at 1200℃ for 3 hours. After natural cooling, obtain ZrO2@α-Al2O3 core-shell particles.

[0053] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 14g of bisphenol A cyanate, and dissolve them together in 250mL of tetrahydrofuran solvent, stirring until completely dissolved. After purging the system with nitrogen, add 0.16g of 2-phenyl-4,6-bis(dimethylamino)triazine accelerator, heat in an oil bath to 75℃, and mechanically stir at 300rpm to carry out the prepolymerization reaction. After stirring continuously for 60 minutes, stop the reaction to obtain the prepolymer, which should be sealed and stored away from light.

[0054] Step 4: Weigh 10g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.3g of phenyltrimethoxysilane, add them to 300mL of toluene solvent, then add 10mL of deionized water, stir well, and reflux at 110℃ for 3 hours to perform surface grafting modification. After the reaction is complete, filter the product, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60℃ for 4 hours to obtain modified ZrO2@α-Al2O3 core-shell particles for later use.

[0055] 60g of bisphenol A epoxy resin was placed in a vacuum mixing vessel, and 100g of 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 sequentially. The mixture was stirred at 500rpm for 30 minutes under a vacuum of 0.1MPa to remove bubbles. The mixed resin was injected into a mold, and a stepped curing procedure was performed: the temperature was increased to 130℃ at a rate of 2℃ / min and held for 60 minutes; then increased to 180℃ at a rate of 3℃ / min and held for 120 minutes; finally, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 180 minutes. After naturally cooling to room temperature, the material was demolded to obtain a high-temperature resistant LED encapsulation material.

[0056] Example 5

[0057] A method for preparing a light-emitting diode (LED) packaging material includes the following steps:

[0058] Step 1: Weigh 10g of 4,4'-diaminodiphenyl ether and dissolve it in 300mL of N-methylpyrrolidone solvent. Stir until completely dissolved under continuous nitrogen protection. Weigh 7.5g of pyromellitic dianhydride and slowly add it to the above solution in 5 batches at 10°C ice bath, with each batch spaced 10 minutes apart. After the addition is complete, remove the ice bath, raise the temperature to 50°C, and continuously stir mechanically to carry out the polycondensation reaction for 6 hours to obtain a polyamic acid solution. Then add 3g of zinc borate nanowires and 1g of aluminum nitride powder, and disperse using a 400W ultrasonic disruptor for 30 minutes to obtain a uniform inorganic skeleton-reinforced polyamic acid suspension, which is then sealed for later use.

[0059] Step 2: Measure 500 mL of 0.1 mol / L zirconium oxychloride aqueous solution into a beaker. Adjust the pH of the solution to 9.5 with ammonia water while stirring magnetically to generate a milky white zirconium hydroxide sol. After allowing the sol to stand and age for 24 hours, centrifuge at 12000 rpm for 15 minutes, discard the supernatant, wash the precipitate three times with anhydrous ethanol, and then disperse it in 200 mL of diethylene glycol to obtain a dispersion. Take 300 mL of 0.05 mol / L aluminum sec-butoxide solution and add it dropwise to the above dispersion at a rate of 2 drops / second under an 80℃ water bath. After the addition is complete, transfer it to a high-pressure reactor and hydrothermally react at 180℃ for 12 hours. After drying the reaction product, calcine it in a muffle furnace at 1150℃ for 2 hours. After natural cooling, obtain ZrO2@α-Al2O3 core-shell particles.

[0060] Step 3: Weigh 20g of 4,4'-diphenylmethane bismaleimide and 8g of bisphenol A cyanate, and dissolve them together in 250mL of tetrahydrofuran solvent, stirring until completely dissolved. After purging the system with nitrogen, add 0.10g of 2-phenyl-4,6-bis(dimethylamino)triazine accelerator, heat in an oil bath to 75℃, and mechanically stir at 300rpm to carry out the prepolymerization reaction. After stirring continuously for 60 minutes, stop the reaction to obtain the prepolymer, which should be sealed and stored away from light.

[0061] Step 4: Weigh 10g of the ZrO2@α-Al2O3 core-shell particles prepared in step b) and 0.1g of phenyltrimethoxysilane, add them to 300mL of toluene solvent, then add 10mL of deionized water, stir well, and reflux at 110℃ for 3 hours to perform surface grafting modification. After the reaction is complete, filter the product, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60℃ for 4 hours to obtain modified ZrO2@α-Al2O3 core-shell particles for later use.

[0062] 60g of bisphenol A epoxy resin was placed in a vacuum mixing vessel, and 100g of 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 sequentially. The mixture was stirred at 500rpm for 30 minutes under a vacuum of 0.1MPa to remove bubbles. The mixed resin was injected into a mold, and a stepped curing procedure was performed: the temperature was increased to 130℃ at a rate of 2℃ / min and held for 60 minutes; then increased to 180℃ at a rate of 3℃ / min and held for 120 minutes; finally, the temperature was increased to 200℃ at a rate of 1℃ / min and held for 180 minutes. After naturally cooling to room temperature, the material was demolded to obtain a high-temperature resistant LED 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 LED 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 in step 4 of the LED packaging material preparation process are not modified.

[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 LED 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 for the test, in accordance with ASTM D3418 standard. Approximately 10 mg of sample was taken and heated from room temperature to 300 °C at a heating rate of 10 °C / min under a nitrogen atmosphere. The inflection point temperature at which the baseline shifted in the heat flow curve was recorded was the glass transition temperature. The test results are shown in Table 1.

[0069] 2. Thermal decomposition temperature test: Thermogravimetric analysis (TGA) was used, referring to ASTM E1131 standard. A 10 mg sample was taken and heated from room temperature to 600 °C at a rate of 10 °C / min in a nitrogen atmosphere. The temperature at which the sample mass loss reaches 5% is the thermal decomposition temperature. The test results are shown in Table 1.

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

[0071] 4. High-Temperature Aging Hardness Retention Rate Test: The initial hardness of the samples was measured using a Shore D hardness tester according to ASTM D2240 standard. The samples were then aged in a 250℃ oven for 1000 hours, and the hardness was measured again after cooling. The hardness retention rate was calculated as (hardness after aging / initial hardness) × 100%. A higher value indicates better high-temperature mechanical property stability of the material. The test results are shown in Table 1.

[0072] Table 1:

[0073]

[0074] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a light-emitting diode (LED) packaging material, characterized in that, Includes the following steps: a) Dissolve 4,4'-diaminodiphenyl ether in N-methylpyrrolidone, and under nitrogen protection, add pyromellitic dianhydride to carry out a polycondensation reaction to obtain a polyamic acid solution. Then add zinc borate nanowires and aluminum nitride powder to the solution and disperse them by ultrasonication to obtain an inorganic skeleton-reinforced polyamic acid suspension. b) The pH of the zirconium oxychloride aqueous solution was adjusted with ammonia to generate zirconium hydroxide sol. After aging, separation and washing, it was dispersed in diethylene glycol. Then, aluminum sec-butoxide solution was added dropwise. After hydrothermal reaction and high-temperature calcination, ZrO2@α-Al2O3 core-shell particles were obtained. c) Dissolve 4,4'-diphenylmethane bismaleimide and bisphenol A cyanate in tetrahydrofuran and carry out a prepolymerization reaction in the presence of 2-phenyl-4,6-bis(dimethylamino)triazine accelerator to obtain a prepolymer; d) Bisphenol A type epoxy resin, inorganic skeleton-reinforced polyamic acid suspension, ZrO2@α-Al2O3 core-shell particles, prepolymer and 2-hydroxy-4-methoxybenzophenone are mixed evenly under vacuum and degassed. After being injected into a mold, the mixture is successively heated and cured, and then naturally cooled and demolded to obtain the light-emitting diode encapsulation material.

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

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

4. The method for preparing a light-emitting diode packaging material according to claim 1, characterized in that, In step b), the calcination temperature is 1150–1200℃ 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 step c), the mass ratio of 4,4'-diphenylmethane bismaleimide to bisphenol A cyanate is 10:4 to 7.

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

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

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

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

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