High-moisture-proof cold-punching-resistant LED packaging silica gel composition and preparation method thereof

Abstract

According to the high-moisture-proof cold-punching-resistant LED packaging silica gel composition and the preparation method thereof, the A and B double-component collaborative design is adopted, the sulfur-containing auxiliary agent is introduced into the A component to react with an LED support silver coating, the chemical bonding force is remarkably enhanced, meanwhile, the special bonding agent is matched, a pollution layer on the surface of the support can be penetrated, and the composition participates in a cross-linked network, so that the moisture-proof cold-punching-resistant LED packaging silica gel composition is formed. And the'interface-body 'integrated combination is realized. The nitrogen-containing auxiliary is introduced into the component B and can form hydrogen bonds or dipole interaction with polar groups on the surfaces of plastics such as PPA, PCT and EMC, meanwhile, the wetting spreadability of the sizing material on a low-surface-energy base material is improved, and the adaptability of the sizing material to various scaffolds is remarkably improved. After the component A and the component B are mixed, a compact cross-linked network is formed under the action of a Karstedt catalyst, and gradient heating and curing rate control in the preparation process are combined, so that internal stress concentration is effectively inhibited, and the packaging adhesive is free of cracking and layering in reflow soldering and cold and hot impact and has excellent moisture resistance.

Description

[Technical Field] This invention belongs to the field of LED packaging material preparation technology, and particularly relates to a high moisture-proof and cold-shock-resistant LED packaging silicone composition and its preparation method. [Background Technology] LED encapsulation silicone is an organosilicon material specifically designed for encapsulating light-emitting diodes (LEDs). Its main function is to protect the LED chip from external environmental influences, while also possessing excellent optical properties to ensure efficient light output. It is commonly used in LED devices as a lens, filler, or capping layer.

[0001] With the rapid development of LED technology and its expanding application scenarios, higher requirements are being placed on the comprehensive performance of encapsulation materials. LED encapsulation silicone not only needs to possess excellent optical transmittance, thermal stability, and weather resistance, but also needs to maintain structural integrity and interface adhesion reliability under harsh environmental conditions. Among these, moisture resistance and cold shock resistance are particularly critical: the former directly affects the reliability of the device in high-temperature reflow soldering or humid environments, while the latter determines whether the LED chip will experience encapsulation layer peeling, cracking, or even "failure" during thermal shock or sudden temperature changes.

[0002] However, the current LED packaging industry chain still faces multiple challenges. On the one hand, some packaging manufacturers omit the LED chip sealing and packaging process or reuse highly hygroscopic sprue plastic materials to reduce costs, leading to increased water absorption of the bracket. During reflow soldering, the moisture expands rapidly, causing the encapsulating adhesive to crack, delaminate, and fail. On the other hand, the interfacial adhesion between existing encapsulating silicone and the bracket (especially the silver plating layer) is insufficient, making it difficult to resist the internal stress generated by moisture expansion, further exacerbating moisture-proof failure. In addition, under high and low temperature cycling or thermal shock conditions, traditional silicone materials are prone to interfacial delamination due to poor modulus matching or insufficient cohesive strength. This delamination problem is difficult to control effectively, especially in large-scale production with a wide variety of substrates and processes. At the same time, traditional materials also have shortcomings in high temperature resistance, sulfur resistance, and long-term aging stability, making it difficult to meet the application requirements of high-power, high-brightness, and long-life LED products.

[0003] Although existing technologies have attempted to improve certain properties by introducing specific resin structures, adding silane coupling agents or functional additives, they often come at the expense of other aspects: they may focus on resistance to vulcanization while neglecting cold stamping and peeling, or improve adhesion while sacrificing moisture / aging resistance, or be effective on specific supports but lack universal compatibility with a variety of substrates (such as PPA, PCT, EMC, etc.). [Summary of the Invention] To address the problems of LED encapsulation silicone in the prior art, this invention provides an LED encapsulation silicone composition with both high moisture resistance and excellent cold-shock resistance, as well as a method for its preparation.

[0004] This invention is achieved by the following technical solution: A highly moisture-proof and cold-shock-resistant LED encapsulation silicone composition, comprising component A and component B, Component A, by weight, comprises the following components: 40-60 parts of vinyl silicone resin; 20-35 parts of dimethyldiphenylvinyl silicone oil; 10-20 parts of hydrogen-containing silicone oil; 3-8 parts adhesive; 1-3 parts of sulfur-containing additives; Anti-aging agent 0.3-1 part; 0.1-0.5 parts of defoamer; 0.0005-0.0008 parts of Karstedt catalyst; Component B, by weight, comprises the following components: 40-60 parts of vinyl silicone resin; 20-35 parts of methylphenyl hydrogen-containing silicone oil; Inhibitor 3-8 parts; 1-3 parts nitrogen-containing additives.

[0005] This invention employs a two-component design (A and B), achieving high moisture resistance and excellent resistance to thermal shock through functional division and synergistic reaction. Component A uses vinyl silicone resin as its matrix. By introducing sulfur-containing additives, the active sulfur groups of these additives strongly complex with the silver plating layer of the LED bracket, significantly enhancing the chemical adhesion between the silicone and the silver plating layer. Simultaneously, a specialized adhesive with excellent affinity and strong migration penetration to organic substrates effectively penetrates the oxide layer, release agent residue, or micro-contamination film on the bracket surface. Its reactive groups participate in the cross-linking network of the silicone, achieving integrated "interface-bulk" bonding and significantly improving adhesion. Under the action of a Karstedt catalyst, the vinyl groups in component A undergo a highly efficient hydrosilylation reaction with the hydrogen-containing silicone oil, forming a dense three-dimensional cross-linked network. By controlling the curing rate, the volume shrinkage and internal stress concentration caused by rapid cross-linking are effectively suppressed. This allows the encapsulation layer to uniformly disperse the localized stress generated by moisture expansion during reflow soldering, preventing interface debonding or colloid cracking, thereby significantly improving moisture resistance and impact resistance. Component B also uses vinyl silicone resin as a matrix, providing sufficient vinyl reaction sites to ensure that it forms a structurally continuous and mechanically uniform crosslinking system after mixing with component A. At the same time, by introducing nitrogen-containing additives, it can form hydrogen bonds or dipole interactions with polar groups on the surface of plastics such as PPA, PCT, and EMC, and also has the functions of interface activation and slow-release curing, improving the wetting and spreading properties of the adhesive on low surface energy substrates. This significantly improves the universality and reliability of encapsulation silicone for bonding various support materials such as non-polar (such as PPA), weakly polar (such as PCT), and metal coatings.

[0006] Preferably, the mass ratio of component A to component B is 1:1 to 3:2.

[0007] Preferably, the adhesive is one or more of the following: a silane coupling agent containing epoxy and vinyl bifunctional groups, a hydrosilicone resin, and pentaerythritol triallyl ether (APE).

[0008] The adhesives of this invention contain active groups that can participate in hydrosilylation or condensation reactions. During the curing process, they not only firmly bond to the surface of the scaffold but also covalently integrate into the interior of the silicone three-dimensional network, significantly improving the interfacial adhesion performance and durability. Among them, epoxy-vinylsilane coupling agent undergoes ring-opening addition or hydrogen bonding with oxides, adsorbed hydroxyl groups or polar groups (such as -COOH, -NH2) on the surface of silver plating layer through epoxy groups. At the same time, its vinyl groups participate in hydrosilylation reaction efficiently, achieving dual anchoring of metal plating layer and organic plastic. Hydrogen-containing silicone resin, as a multifunctional crosslinking aid, not only improves network crosslinking density and cohesive strength through Si-H reaction with vinyl groups, but its branched structure also helps to improve the compatibility of silicone with inorganic / organic interfaces and strengthen the bonding of transition zones. APE, as a small molecule adhesive, has the characteristics of low molecular weight, moderate polarity and low viscosity. It can quickly diffuse to silicone / scaffold interface in the early stage of adhesive mixing, effectively penetrating the release agent residue, oxide layer or micro-contamination film commonly found on the surface of PPA, PCT and other engineering plastic scaffolds. Its allyl groups can also partially participate in hydrosilylation during curing, providing auxiliary chemical anchoring.

[0009] More preferably, the silane coupling agent containing epoxy and vinyl bifunctional groups is a mixture of γ-glycidoxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane.

[0010] Preferably, the sulfur-containing additive is one or more of calcium sulfate, aluminum sulfate, zinc sulfate, bis-(γ-triethoxysilylpropyl)tetrasulfide (SI69), and mercaptopropyltrimethoxysilane.

[0011] The sulfur-containing additive of this invention utilizes the strong complexation between its active sulfur groups and the silver plating layer of the LED bracket to significantly enhance the chemical adhesion between the silicone and the silver plating layer.

[0012] Preferably, the vinyl silicone resin has a molecular weight of 8000-12000 and a solid content of 70-75%.

[0013] Preferably, the solid content of the dimethyldiphenylvinyl silicone oil, the hydrogen-containing silicone oil, and the methylphenyl hydrogen-containing silicone oil is all 90-95%.

[0014] Preferably, the antioxidant is one or more of phenolic antioxidants and amine antioxidants.

[0015] Preferably, the defoamer is one or more of silicone-based defoamers and polyether-based defoamers.

[0016] Preferably, the nitrogen-containing adjuvant is a mixture of a nitrogen-containing coupling agent and an imidazole compound.

[0017] More preferably, the nitrogen-containing coupling agent is one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; and the imidazole compound is one or more of imidazole and benzimidazole.

[0018] Preferably, the mass ratio of the nitrogen-containing coupling agent to the imidazole compound is 1:4 to 5:1, more preferably 1:2 to 4:1.

[0019] This invention utilizes a nitrogen-containing additive system combining highly reactive aminosilanes and multifunctional imidazole compounds to significantly improve the universality and reliability of encapsulated silicone adhesives on multi-component substrates. Specifically, the primary and secondary amine groups in the aminosilane can form strong hydrogen bonds or dipole-dipole interactions with polar functional groups such as amide and carboxyl groups on the surface of engineering plastics like PPA, PCT, and EMC. Simultaneously, the hydrolyzed silanol groups can condense with hydroxyl groups on the substrate surface to construct stable Si-O-substrate covalent bonds. The imidazole compounds, with their weak basicity and aromatic heterocyclic structure, can neutralize trace acidic impurities on the scaffold surface, reduce interfacial tension, and improve the wetting and spreading properties of the adhesive on low surface energy substrates.

[0020] The method for preparing the high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: Parts by weight of vinyl silicone resin, dimethyl diphenyl vinyl silicone oil, hydrogen-containing silicone oil, adhesive, sulfur-containing additives, catalyst, antioxidant, defoamer, and Karstedt catalyst are stirred at 300-500 rpm for 15-20 minutes at room temperature until no particulate impurities are found, to obtain component A; parts by weight of vinyl silicone resin, methyl phenyl hydrogen-containing silicone oil, inhibitor, and nitrogen-containing additives are stirred at 300-500 rpm for 15-20 minutes at room temperature until no particulate impurities are found, to obtain component B. S2. Mixing: Mix component A and component B from step S1 at 60-70°C and 600-800 r / min for 30-60 min according to the mass ratio to obtain a mixture; S3. Curing: The mixture described in step S2 is heated at 5-8℃ / h and cured at 60-70℃ for 2-4h, with the curing rate controlled at 0.8-1.2mm / h to ensure that the adhesive reacts fully and to obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 80-100℃ for 4-8 hours to remove residual moisture and impurities, thereby obtaining a high moisture-proof and cold-impact-resistant LED encapsulation silicone composition.

[0021] The beneficial effects of this invention are as follows: This invention provides a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition, employing a synergistic design of two components, A and B. Component A introduces a sulfur-containing additive that reacts with the silver plating layer of the LED bracket, significantly enhancing chemical adhesion. Simultaneously, a specialized adhesive penetrates the contamination layer on the bracket surface and participates in the cross-linking network, achieving integrated "interface-bulk" bonding. Component B introduces a nitrogen-containing additive that forms hydrogen bonds or dipole interactions with polar groups on the surfaces of plastics such as PPA, PCT, and EMC, improving the wettability and spreadability of the adhesive on low surface energy substrates and significantly enhancing its compatibility with various bracket types. After mixing, components A and B form a dense cross-linked network under the action of a Karstedt catalyst. Combined with gradient temperature rise and curing rate control in the preparation process, internal stress concentration is effectively suppressed, ensuring the encapsulation adhesive exhibits no cracking or delamination during reflow soldering and thermal shock, while also providing excellent moisture resistance.

[0022] This invention also provides a method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition. Through a four-step process of premixing, temperature-controlled mixing, gradient curing, and post-drying, it achieves stable component dispersion, sufficient migration of interfacial additives, low internal stress construction of the cross-linked network, and complete removal of residual moisture. In particular, the use of a 5-8℃ / h gradient temperature increase and controlled curing rate of 0.8-1.2mm / h effectively ensures sufficient reaction of the adhesive at the interface, significantly suppressing delamination and cracking during reflow soldering. Combined with 80-100℃ ventilation post-treatment, it greatly reduces internal moisture residue, giving the encapsulation silicone excellent moisture resistance, thermal shock resistance, and long-term reliability, meeting the stringent application requirements of high-power, high-reliability LED devices.

Detailed Implementation Methods

[0023] Example 2 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: Component A is obtained by mixing 45 parts by weight of vinyl silicone resin, 25 parts by weight of dimethyl diphenyl vinyl silicone oil, 18 parts by weight of hydrogen-containing silicone oil, 6 parts by weight of APE, 1.5 parts by weight of mercaptopropyltrimethoxysilane, 0.8 parts by weight of amine antioxidant, 0.4 parts by weight of polyether defoamer, and 0.0007 parts by weight of Karstedt catalyst at 350 rpm for 16 min at room temperature until no particulate impurities are found. Component B is obtained by mixing 50 parts by weight of vinyl silicone resin, 30 parts by weight of methylphenyl hydrogen-containing silicone oil, 6 parts by weight of inhibitor, and 2.5 parts by weight of nitrogen-containing additives (N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and benzimidazole in a mass ratio of 2:1) at 350 rpm for 16 min at room temperature until no particulate impurities are found. S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 2:3 at 70°C and 750 r / min for 50 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the MTC tri-crystalline PCT easy-peeling bracket, heat it to 70°C at a heating rate of 7°C / h, and cure it at 70°C for 3.5h. Control the curing rate to 1.1mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The solidified material described in step S3 is dried in an air-dryer at 95°C for 7 hours to remove residual moisture and impurities, and the finished product is obtained.

[0024] Example 3 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: 55 parts by weight of vinyl silicone resin, 28 parts by weight of dimethyl diphenyl vinyl silicone oil, 12 parts by weight of hydrogen-containing silicone oil, 4 parts by weight of hydrogen-containing silicone resin, 2.5 parts by weight of zinc sulfate, 0.7 parts by weight of phenolic antioxidant, 0.2 parts by weight of organosilicon defoamer, and 0.0005 parts by weight of Karstedt catalyst are stirred at 450 r / min for 17 min at room temperature until no particulate impurities are found, to obtain component A; 45 parts by weight of vinyl silicone resin, 33 parts by weight of methyl phenyl hydrogen-containing silicone oil, 5 parts by weight of inhibitor, and 1.5 parts by weight of nitrogen-containing auxiliary agent (N-(β-aminoethyl)-γ-aminopropyltriethoxysilane and imidazole in a mass ratio of 1:2) are stirred at 450 r / min for 17 min at room temperature until no particulate impurities are found, to obtain component B; S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 3:2 at 62°C and 650 r / min for 40 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the 2835 PPA bracket, heat it to 65°C at a heating rate of 5°C / h, and cure it at 65°C for 2.5h. Control the curing rate to be 0.9mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 85°C for 5 hours to remove residual moisture and impurities, and the finished product is obtained.

[0025] Example 4 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: Component A is obtained by mixing 42 parts by weight of vinyl silicone resin, 32 parts by weight of dimethyl diphenyl vinyl silicone oil, 16 parts by weight of hydrogen-containing silicone oil, 7 parts by weight of APE, 1.2 parts by weight of aluminum sulfate, 0.4 parts by weight of amine antioxidant, 0.3 parts by weight of polyether defoamer, and 0.0008 parts by weight of Karstedt catalyst at 380 rpm for 19 min at room temperature until no particulate impurities are found. Component B is obtained by mixing 52 parts by weight of vinyl silicone resin, 28 parts by weight of methyl phenyl hydrogen-containing silicone oil, 4 parts by weight of inhibitor, and 1.8 parts by weight of nitrogen-containing additive (a mixture of γ-aminopropyltriethoxysilane and benzimidazole in a mass ratio of 3:1) at 380 rpm for 19 min at room temperature until no particulate impurities are found. S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 1:1 at 68°C and 720 r / min for 55 min to obtain a mixture; S3. Curing: The mixture described in step S2 is injected into the Zhongyang three-crystal cup support, heated to 66°C at a heating rate of 6.5°C / h, and cured at 66°C for 3h. The curing rate is controlled at 1.0mm / h to ensure that the adhesive reacts fully and a cured product is obtained. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 92°C for 6.5 hours to remove residual moisture and impurities, and the finished product is obtained.

[0026] Example 5 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: Component A is obtained by mixing 58 parts by weight of vinyl silicone resin, 22 parts by weight of dimethyl diphenyl vinyl silicone oil, 14 parts by weight of hydrogen-containing silicone oil, 3 parts by weight of a copolymer of γ-glycidyl etheroxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane, 2.8 parts by weight of a sulfur-containing additive compounded with SI69 and calcium sulfate in a 2:1 mass ratio, 0.9 parts by weight of phenolic antioxidant, 0.4 parts by weight of organosilicon defoamer, and 0.00065 parts by weight of Karstedt catalyst at 420 rpm for 15 min at room temperature until no particulate impurities are found. Component B is obtained by mixing 48 parts by weight of vinyl silicone resin, 31 parts by weight of methylphenyl hydrogen-containing silicone oil, 7 parts by weight of inhibitor, and 2.2 parts by weight of a nitrogen-containing additive compounded with N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane and imidazole in a 2:3 mass ratio at room temperature for 15 min until no particulate impurities are found. S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 2:1 at 64°C and 680 r / min for 35 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the MLS Tricrystalline PCT scaffold, heat it to 63°C at a heating rate of 7.5°C / h, and cure it at 63°C for 2.8h. Control the curing rate to 1.1mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 88°C for 5.5 hours to remove residual moisture and impurities, and the finished product is obtained.

[0027] Example 6 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: Component A is obtained by mixing 47 parts by weight of vinyl silicone resin, 29 parts by weight of dimethyl diphenyl vinyl silicone oil, 17 parts by weight of hydrogen-containing silicone oil, 6.5 parts by weight of APE, 1.7 parts by weight of sulfur-containing additives (a mixture of mercaptopropyltrimethoxysilane and zinc sulfate in a 3:2 mass ratio), 0.6 parts by weight of amine antioxidant, 0.2 parts by weight of polyether defoamer, and 0.00055 parts by weight of Karstedt catalyst at 360 rpm for 20 min at room temperature until no particulate impurities are found. Component B is obtained by mixing 53 parts by weight of vinyl silicone resin, 26 parts by weight of methylphenyl hydrogen-containing silicone oil, 5.5 parts by weight of inhibitor, and 1.3 parts by weight of nitrogen-containing additives (a mixture of γ-aminopropyltriethoxysilane and benzimidazole in a 1:1 mass ratio) at 360 rpm for 20 min at room temperature until no particulate impurities are found. S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 3:2 at 67°C and 730 r / min for 48 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the MTC tri-crystalline PCT substrate, heat it to 69°C at a heating rate of 5.5°C / h, and cure it at 69°C for 3.2h. Control the curing rate to 1.0mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 94°C for 6.8 hours to remove residual moisture and impurities, and the finished product is obtained.

[0028] Example 7 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: Component A is obtained by mixing 40 parts by weight of vinyl silicone resin, 35 parts by weight of dimethyl diphenyl vinyl silicone oil, 10 parts by weight of hydrogen-containing silicone oil, 8 parts by weight of an adhesive compounded from APE and hydrogen-containing silicone resin in a 3:2 mass ratio, 1 part by weight of SI69, 0.3 parts by weight of phenolic antioxidant, 0.3 parts by weight of silicone defoamer, and 0.00075 parts by weight of Karstedt catalyst at 390 rpm for 16 min at room temperature until no particulate impurities are found. Component B is obtained by mixing 60 parts by weight of vinyl silicone resin, 20 parts by weight of methyl phenyl hydrogen-containing silicone oil, 3 parts by weight of inhibitor, and 1 part by weight of a nitrogen-containing additive compounded from N-(β-aminoethyl)-γ-aminopropyltriethoxysilane and benzimidazole in a 4:1 mass ratio at room temperature for 16 min at 390 rpm until no particulate impurities are found. S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 1:1 at 60°C and 600 r / min for 30 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the small LED indicator PPA bracket, heat it to 60°C at a heating rate of 5°C / h, and cure it at 60°C for 2 hours. Control the curing rate to be 0.8 mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 80°C for 4 hours to remove residual moisture and impurities, and the finished product is obtained.

[0029] Example 8 A method for preparing a high moisture-proof and cold-shock-resistant LED encapsulation silicone composition includes the following steps: S1. Pretreatment: 60 parts by weight of vinyl silicone resin, 20 parts by weight of dimethyl diphenyl vinyl silicone oil, 20 parts by weight of hydrogen-containing silicone oil, 3 parts by weight of APE, 3 parts by weight of calcium sulfate, 1 part by weight of amine antioxidant, 0.5 parts by weight of polyether defoamer, and 0.0006 parts by weight of Karstedt catalyst are stirred at 480 rpm for 17 min at room temperature until no particulate impurities are found, to obtain component A; 40 parts by weight of vinyl silicone resin, 35 parts by weight of methyl phenyl hydrogen-containing silicone oil, 8 parts by weight of inhibitor, and 3 parts by weight of nitrogen-containing additives (γ-aminopropyltriethoxysilane and imidazole compounded in a mass ratio of 2:1) are stirred at 480 rpm for 17 min at room temperature until no particulate impurities are found, to obtain component B; S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 3:2 at 70°C and 800 r / min for 60 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the PCT bracket of the high-power LED floodlight, heat it to 70°C at a heating rate of 8°C / h, and cure it at 70°C for 4 hours. Control the curing rate to 1.2 mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 100°C for 8 hours to remove residual moisture and impurities, and the finished product is obtained.

[0030] Comparative Example 1 A method for preparing an LED encapsulation silicone composition includes the following steps: S1. Pretreatment: 50 parts by weight of vinyl silicone resin, 30 parts by weight of dimethyl diphenyl vinyl silicone oil, 15 parts by weight of hydrogen-containing silicone oil, 2 parts by weight of SI69, 0.5 parts by weight of phenolic antioxidant, 0.3 parts by weight of organosilicon defoamer, and 0.0006 parts by weight of Karstedt catalyst are stirred at 400 rpm for 18 min at room temperature until no particulate impurities are found, to obtain component A; 55 parts by weight of vinyl silicone resin, 25 parts by weight of methyl phenyl hydrogen-containing silicone oil, 5 parts by weight of inhibitor, and 2 parts by weight of nitrogen-containing additive (γ-aminopropyltriethoxysilane and imidazole in a mass ratio of 1:1) are stirred at 400 rpm for 18 min at room temperature until no particulate impurities are found, to obtain component B; S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 1:1 at 65°C and 700 r / min for 45 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the Liangyou 2835 PPA bracket, heat it to 68°C at a heating rate of 6°C / h, and cure it at 68°C for 3 hours. Control the curing rate to 1.0 mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The solidified material described in step S3 is dried in a ventilated environment at 90°C for 6 hours to remove residual moisture and impurities, and the finished product is obtained.

[0031] Comparative Example 2 A method for preparing an LED encapsulation silicone composition includes the following steps: S1. Pretreatment: 50 parts by weight of vinyl silicone resin, 30 parts by weight of dimethyl diphenyl vinyl silicone oil, 15 parts by weight of hydrogen-containing silicone oil, 5 parts by weight of APE, 0.5 parts by weight of phenolic antioxidant, 0.3 parts by weight of organosilicon defoamer, and 0.0006 parts by weight of Karstedt catalyst are stirred at 400 rpm for 18 min at room temperature until no particulate impurities are found, to obtain component A; 55 parts by weight of vinyl silicone resin, 25 parts by weight of methyl phenyl hydrogen-containing silicone oil, 5 parts by weight of inhibitor, and 2 parts by weight of nitrogen-containing additive (γ-aminopropyltriethoxysilane and imidazole in a mass ratio of 1:1) are stirred at 400 rpm for 18 min at room temperature until no particulate impurities are found, to obtain component B; S2. Mixing: Mix component A and component B from step S1 at a mass ratio of 1:1 at 65°C and 700 r / min for 45 min to obtain a mixture; S3. Curing: Inject the mixture described in step S2 into the Liangyou 2835 PPA bracket, heat it to 68°C at a heating rate of 6°C / h, and cure it at 68°C for 3 hours. Control the curing rate to 1.0 mm / h to ensure that the adhesive reacts fully and obtain the cured product. S4. Post-processing: The solidified material described in step S3 is dried in a ventilated environment at 90°C for 6 hours to remove residual moisture and impurities, and the finished product is obtained.

[0032] The finished products obtained in Examples 1-8 and Comparative Examples 1-2 were subjected to tests for hardness, viscosity, sulfur aging resistance, moisture resistance, thermal shock resistance, and high-temperature reflow soldering resistance. The test standards and conditions are as follows: Hardness test: The test was conducted using a Shore D hardness tester in accordance with GB / T 531.1-2008. Viscosity test: According to GB / T 10247-2008, the viscosity was tested at 25℃ using a rotational viscometer; Sulfur aging resistance test: According to IEC 61701-2014, the test was conducted in a hydrogen sulfide gas environment with a concentration of 50 ppb, at a temperature of 40℃ and a humidity of 85%RH. The duration of time during which the material showed no obvious aging (transmittance decrease ≤5%) was recorded. Moisture resistance test: According to IPC / JEDEC J-STD-020D, tests were conducted at 85℃ / 85%RH, 1h (double 85 / 1H) and room temperature (25℃), and 7 days to observe whether the adhesive cracked and to calculate the delamination rate. Thermal shock resistance test: According to GB / T 2423.22-2012, the temperature was rapidly switched between -45℃ (hold for 15 min) and 125℃ (hold for 15 min), and the maximum number of cycles without peeling, cracking, or dead light was recorded. High-temperature reflow soldering test: According to IPC / JEDEC J-STD-020D, three reflow soldering cycles were performed at 260℃, with the peak temperature held for 10 seconds in each cycle. The integrity of the package structure and changes in performance were observed.

[0033] Table 1 Performance test results of Examples 1-4

[0034] Table 2 Performance test results of Examples 5-8

[0035] Table 3 Performance test results of Comparative Examples 1-2

[0036] As shown in Tables 1-3, the LED encapsulation silicone compositions prepared in Examples 1-8 of the present invention meet the basic performance standards in terms of hardness, viscosity, etc., and their sulfur aging resistance, moisture resistance, thermal shock resistance, and high-temperature reflow soldering resistance are significantly better than those of Comparative Examples 1-2 without adhesives or sulfur-containing additives.

[0037] The above examples are merely illustrative of the technical content of the present invention to facilitate easier understanding by the reader, but do not imply that the implementation of the present invention is limited to these examples. Any technical extensions or re-creations made based on the present invention are protected by the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A high moisture-proof and cold-shock-resistant LED encapsulation silicone composition, comprising component A and component B, characterized in that: Component A, by weight, comprises the following components: 40-60 parts of vinyl silicone resin; 20-35 parts of dimethyldiphenylvinyl silicone oil; 10-20 parts of hydrogen-containing silicone oil; 3-8 parts adhesive; 1-3 parts of sulfur-containing additives; Anti-aging agent 0.3-1 part; 0.1-0.5 parts of defoamer; 0.0005-0.0008 parts of Karstedt catalyst; Component B, by weight, comprises the following components: 40-60 parts of vinyl silicone resin; 20-35 parts of methylphenyl hydrogen-containing silicone oil; Inhibitor 3-8 parts; 1-3 parts nitrogen-containing additives.

2. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The mass ratio of component A to component B is 1:1 to 3:

2.

3. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The adhesive is one or more of the following: silane coupling agent containing epoxy and vinyl bifunctional groups, hydrosilicone resin, and pentaerythritol triallyl ether (APE).

4. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 3, characterized in that: The silane coupling agent containing epoxy and vinyl bifunctional groups is a mixture of γ-glycidoxypropyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane.

5. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The sulfur-containing additive is one or more of calcium sulfate, aluminum sulfate, zinc sulfate, bis-(γ-triethoxysilylpropyl)tetrasulfide (SI69), and mercaptopropyltrimethoxysilane.

6. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The vinyl silicone resin has a molecular weight of 8000-12000 and a solid content of 70-75%.

7. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The solid content of the dimethyldiphenylvinyl silicone oil, the hydrogen-containing silicone oil, and the methylphenyl hydrogen-containing silicone oil is all 90-95%.

8. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The antioxidant is one or more of phenolic antioxidants and amine antioxidants; the defoamer is one or more of organosilicon defoamers and polyether defoamers.

9. The high moisture-proof and cold-impact-resistant LED encapsulation silicone composition according to claim 1, characterized in that: The nitrogen-containing auxiliary agent is a mixture of nitrogen-containing coupling agents and imidazole compounds; the nitrogen-containing coupling agent is one or more of γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane; the imidazole compound is one or more of imidazole and benzimidazole.

10. The method for preparing the high moisture-proof and cold-shock-resistant LED encapsulation silicone composition according to any one of claims 1-9, characterized in that: Includes the following steps: S1. Pretreatment: Parts by weight of vinyl silicone resin, dimethyl diphenyl vinyl silicone oil, hydrogen-containing silicone oil, adhesive, sulfur-containing additives, catalyst, antioxidant, defoamer, and Karstedt catalyst are stirred at 300-500 rpm for 15-20 minutes at room temperature until no particulate impurities are found, to obtain component A; parts by weight of vinyl silicone resin, methyl phenyl hydrogen-containing silicone oil, inhibitor, and nitrogen-containing additives are stirred at 300-500 rpm for 15-20 minutes at room temperature until no particulate impurities are found, to obtain component B. S2. Mixing: Mix component A and component B from step S1 at 60-70°C and 600-800 r / min for 30-60 min according to the mass ratio to obtain a mixture; S3. Curing: The mixture described in step S2 is heated at 5-8℃ / h and cured at 60-70℃ for 2-4h, with the curing rate controlled at 0.8-1.2mm / h to ensure that the adhesive reacts fully and to obtain the cured product. S4. Post-processing: The cured material described in step S3 is dried in an air-dryer at 80-100℃ for 4-8 hours to remove residual moisture and impurities, thereby obtaining a high moisture-proof and cold-impact-resistant LED encapsulation silicone composition.

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