Coating type adhesive for light emitting diode and preparation method of coating type adhesive
By forming a high crosslink density network and interpenetrating network with benzoxazine, the problem of insufficient UV resistance and temperature resistance of coated adhesives is solved, and the comprehensive performance of adhesives is improved, and suitable for LED packaging is suitable.
Patent Information
- Application Number
- CN202510717827.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2025-08-26
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
Existing coated adhesives have poor performance in UV resistance and temperature resistance, resulting in reduced luminous efficiency and unbalanced performance.
Epoxy-modified resin and benzoxazine are used to assist in the formation of a three-dimensional network with high cross-linking density, and covalent bonds are formed with the main resin and flexible segments are mechanically interlocked, and interpenetrating networks are formed with the filling composition to improve bonding strength and heat resistance.
It effectively balances the adhesiveness, chemical resistance, ultraviolet resistance and heat resistance of the adhesive, significantly improves the comprehensive performance of coated adhesives, and meets the performance needs of the LED industry.
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Abstract
Description
Technical Field
[0001] The present application relates to the field of adhesives, and more specifically to a coating adhesive for light-emitting diodes and a preparation method thereof. Background Art
[0002] Light-emitting diodes (LEDs), as efficient and energy-saving semiconductor light sources, have been widely used in lighting, display, backlighting, and optical communications. Their core structure includes the LED chip, bracket, electrodes, and packaging materials. The packaging materials are crucial to the LED's optical performance, weather resistance, and reliability. LED packaging typically involves mounting the semiconductor chip on a substrate and encapsulating it with an appropriate material to protect it from environmental factors such as moisture, oxygen, and mechanical damage. The packaging material must not only provide physical protection but also possess good light transmittance, thermal conductivity, and durability.
[0003] As a key packaging material in the packaging process, coating adhesives are mainly used for chip surface protection, phosphor layer fixation, light diffusion layer coating and device sealing, which directly affects the luminous efficiency, heat dissipation, mechanical strength and service life of LEDs.
[0004] Currently, there are numerous types of coating adhesives available, primarily including epoxy, silicone, polyurethane, and modified hybrid systems. Each system has its own performance preferences, but also its own performance drawbacks. In recent years, an analysis of the performance of coating adhesives has revealed that their shortcomings primarily stem from poor performance balance. Coating adhesives with high viscosity and chemical resistance often exhibit poor UV and temperature resistance, and are prone to oxidation, yellowing, and softening over long periods of use, resulting in a decrease in overall light efficiency and, consequently, poor overall adhesive performance. Summary of the Invention
[0005] Therefore, how to effectively improve the overall performance of coating adhesives and balance the contradictions between these properties has become a major problem facing existing coating adhesives for light-emitting diodes. The present applicant, through continuous research in this field, has now proposed a coating adhesive for light-emitting diodes and a method for preparing the same. The coating adhesive ultimately produced by this application is able to maintain excellent adhesion and chemical resistance while maintaining good UV resistance and temperature resistance, effectively balancing the contradictions in these properties. This significantly improves the overall performance of the coating adhesive, meets the performance requirements of the existing LED industry for adhesives, and has broad application potential.
[0006] A coating adhesive for light-emitting diodes comprises the following raw materials, measured in parts by mass: 80-110 parts of epoxy resin, 20-40 parts of functional resin, 40-60 parts of methylhexahydrophthalic anhydride, 10-20 parts of a filling composition, 0.6-1 part of an antioxidant, 0.1-0.3 part of a light stabilizer, 0.3-0.6 part of a leveling agent, 0.1-0.3 part of a defoaming agent, 0.5-0.8 part of a curing accelerator, 3-8 parts of a toughening agent, and 50-70 parts of a solvent.
[0007] As a preferred solution, the epoxy resin is bisphenol A epoxy resin or bisphenol F epoxy resin.
[0008] As a more preferred solution, the epoxy resin is bisphenol A epoxy resin.
[0009] As a preferred solution, the epoxy equivalent of the epoxy resin is 160~240g / eq.
[0010] As a preferred solution, the functional resin is an epoxy-modified resin.
[0011] As a preferred solution, the preparation method of the epoxy-modified resin specifically includes the following steps: S1: adding epoxy acrylate, benzoxazine and 2-hydroxy-4-acrylate benzotriazole to N,N-dimethylacetamide and stirring evenly; S2: adding benzoyl peroxide, replacing with nitrogen, and heating and stirring to react; S3: after the reaction is completed, cooling the reaction solution and pouring it into deionized water for precipitation, filtering, vacuum drying, and crushing and sieving to obtain the product.
[0012] As a more preferred embodiment, the preparation method of the epoxy-modified resin specifically includes the following steps: S1: adding epoxy acrylate, benzoxazine and 2-hydroxy-4-acrylate benzotriazole to N,N-dimethylacetamide, stirring at 65-70°C and 400-500 rpm for 1.5-2 hours until completely uniform; S2: adding benzoyl peroxide, introducing nitrogen to replace the air, and continuing for 10-15 minutes, raising the temperature to 85-90°C and reacting for 7-8 hours, maintaining stirring at 150-200 rpm; S3: after the reaction is completed, cooling the reaction solution to 45-50°C, pouring it into deionized water for precipitation, filtering it, and vacuum drying it at 75-80°C for 10-12 hours, and crushing it through a 400-500 mesh sieve to obtain it.
[0013] As a preferred solution, the mass ratio of the epoxy acrylate, benzoxazine and 2-hydroxy-4-acrylate benzotriazole is (5-7): (2-3): (1.5-2.5).
[0014] As a more preferred solution, the mass ratio of the epoxy acrylate, benzoxazine and 2-hydroxy-4-acrylate benzotriazole is (5.5-6.5): (2.5-3): (2-2.2).
[0015] By adding epoxy-modified resin, the ring-opening cross-linking reaction therein improves the thermal stability of the adhesive layer to adapt to the high-temperature working environment of the LED chip, and by introducing 2-hydroxy-4-acrylate benzotriazole groups, it actively absorbs ultraviolet rays and inhibits the yellowing and light decay of the resin. On the other hand, the modified resin can also form chemical bonds with the main resin through the epoxy groups of epoxy acrylate, reducing interfacial stress and improving bonding strength, thereby greatly enhancing the interaction strength of the molecular chain system and improving the molecular chain's resistance to molecular chain slippage.
[0016] The high-crosslink density, three-dimensional network formed with benzoxazine exhibits higher chemical bond energy and, through lower dielectric loss, reduces heat accumulation under high-frequency operation. Furthermore, the epoxy acrylate groups form covalent bonds with the main resin, while the acrylate segments penetrate the substrate's micropores through the flexible acrylate chains, creating a mechanical interlock. The hydroxyl groups in the epoxy acrylates form hydrogen bonds with oxygen atoms on the substrate surface, ensuring the adhesive's adhesion. Furthermore, the rigid crosslinked network and the flexible acrylate chains interpenetrate each other, restricting molecular segment motion, increasing modulus, and absorbing thermal stress, thereby comprehensively improving the coating adhesive's heat resistance, adhesion, UV resistance, and chemical resistance.
[0017] As a preferred solution, the mass ratio of the epoxy resin, the functional resin, and the methylhexahydrophthalic anhydride is (90-100): (25-30): (50-60).
[0018] As a more preferred solution, the mass ratio of the epoxy resin, the functional resin, and the methylhexahydrophthalic anhydride is (95-100): (25-28): (53-58).
[0019] As a preferred solution, the mass ratio of the epoxy resin to the filling composition is (90-100): (12-20).
[0020] As a more preferred solution, the mass ratio of the epoxy resin to the filling composition is (95-100): (14-16).
[0021] As a preferred solution, the filling composition is a composition of polyetheretherketone, chopped aramid fibers and aluminum borate whiskers.
[0022] As a preferred solution, the mass ratio of the polyetheretherketone, chopped aramid fiber and aluminum borate whisker is (9-12): (7-9): (3-5).
[0023] As a more preferred solution, the mass ratio of the polyetheretherketone, chopped aramid fiber and aluminum borate whisker is (10~11): (7~8): (4~4.5).
[0024] As a preferred solution, the average diameter of the chopped aramid fibers is 10-20 μm, and the average length is 2.5-5 mm.
[0025] As a preferred solution, the aspect ratio of the aluminum borate whiskers is 20-24.
[0026] As a preferred solution, the antioxidant is at least one of the antioxidant DLTDP, antioxidant 2246, antioxidant 168 and antioxidant BHT.
[0027] As a more preferred solution, the antioxidant is antioxidant DLTDP or antioxidant 2246.
[0028] As a preferred solution, the light stabilizer is at least one of UV-327, UV-531, Tinuvin 622 and Tinuvin 329.
[0029] As a more preferred solution, the light stabilizer is UV-327 or Tinuvin 622.
[0030] As a preferred solution, the leveling agent is at least one of acrylates, polyether-modified siloxanes and organosiloxanes.
[0031] As a more preferred solution, the leveling agent is polyether-modified siloxane.
[0032] As a preferred solution, the defoaming agent is at least one of silicone defoaming agents.
[0033] As a preferred solution, the curing accelerator is at least one of 2-ethyl-4-methylimidazole, triphenylphosphine, aluminum acetylacetonate and dicumyl peroxide.
[0034] As a more preferred solution, the curing accelerator is 2-ethyl-4-methylimidazole.
[0035] As a preferred solution, the toughening agent is carboxyl nitrile rubber or hyperbranched polyester.
[0036] As a more preferred solution, the toughening agent is carboxyl nitrile rubber.
[0037] As a preferred solution, the solvent is propylene glycol methyl ether acetate.
[0038] The preparation method of the coating adhesive for light-emitting diodes specifically comprises the following steps: S1: mixing epoxy resin and functional resin at 55-60°C at 800-1000 rpm for 20-30 minutes, then adding the filler composition pre-dispersed with a solvent, and continuing to stir at 1200-1500 rpm for 30-35 minutes; S2: adding methyl hexahydrophthalic anhydride, stirring at 800-1000 rpm for 10-15 minutes, and then adding Add antioxidant, light stabilizer, leveling agent, defoaming agent, curing accelerator and toughening agent, stir at 500-600 rpm for 5-7 minutes each time, degas in vacuum for 1-1.5 hours, filter through a 10 μm nylon filter, and store in the dark. S3: When in use, spray on the surface of the substrate, pre-cure at 75-80°C for 1-1.5 hours, post-cure at 120-125°C for 2-2.5 hours, and finally cure at 145-150°C for 0.8-1 hour.
[0039] This application has the following beneficial effects: 1. The coating adhesive for light-emitting diodes finally prepared in this application has excellent adhesion and chemical resistance while maintaining good UV resistance and temperature resistance, effectively balancing the contradictions in the above properties, thereby greatly improving the comprehensive performance of the coating adhesive, meeting the performance requirements of the existing LED industry for adhesives, and has broad application potential.
[0040] 2. The coating adhesive for light-emitting diodes ultimately produced in this application features a high-crosslink density, three-dimensional network formed by the epoxy-modified resin with the assistance of benzoxazine, exhibiting higher chemical bond energy and, through lower dielectric loss, reducing heat accumulation under high-frequency operation. Furthermore, the epoxy acrylate groups form covalent bonds with the main resin, while the acrylate segments penetrate into the substrate micropores through the flexible acrylate chains, forming a mechanical interlock. The hydroxyl groups contained in the epoxy acrylates form hydrogen bonds with oxygen atoms on the substrate surface, ensuring the adhesive's adhesion. Furthermore, the rigid crosslinked network and the flexible acrylate chains interpenetrate each other, restricting the movement of the molecular segments, increasing the modulus, and absorbing thermal stress, thereby comprehensively improving the coating adhesive's heat resistance, adhesion, UV resistance, and chemical resistance.
[0041] 3. The coating adhesive for light-emitting diodes finally prepared by the present application, with the assistance of the filling composition, forms an interpenetrating network with the epoxy resin through physical entanglement and hydrogen bonding to restrict the movement of resin chain segments, significantly improving the heat deformation temperature; on the other hand, after its addition, it absorbs energy through bridging and pull-out mechanisms, preventing crack propagation and weakening the penetration of moisture and corrosive molecules. The electronic band structure of the whiskers converts light energy into lattice vibration energy through electron transitions, connecting end to end in the coating to form a continuous heat conduction network, shortening the heat conduction path length, improving thermal stability while maintaining good thermal conductivity and UV and chemical resistance. DETAILED DESCRIPTION
[0042] Example 1
[0043] Coating adhesive for light-emitting diodes, coating adhesive for light-emitting diodes, the raw materials are composed of the following components, calculated by mass: 98.5 parts of epoxy resin, 26.4 parts of functional resin, 56 parts of methylhexahydrophthalic anhydride, 14.8 parts of filling composition, 0.6 parts of antioxidant, 0.15 parts of light stabilizer, 0.4 parts of leveling agent, 0.2 parts of defoaming agent, 0.6 parts of curing accelerator, 5.8 parts of toughening agent, and 58 parts of solvent.
[0044] The epoxy resin is a bisphenol A epoxy resin with an epoxy equivalent weight of 190 g / eq, and is purchased from Nan Ya Plastics Industry Co., Ltd. in China as a model E-51 product.
[0045] The functional resin is an epoxy-modified resin, and the preparation method specifically includes the following steps, calculated by mass: S1: adding 5.8 parts of epoxy acrylate, 2.6 parts of benzoxazine and 2.1 parts of 2-hydroxy-4-acrylate benzotriazole to 50 parts of N,N-dimethylacetamide, and stirring at 70°C and 500 rpm for 2 hours until completely uniform; S2: adding 0.14 parts of benzoyl peroxide, introducing nitrogen to replace the air, and continuing for 15 minutes, heating to 90°C and reacting for 8 hours, maintaining stirring at 200 rpm; S3: after the reaction is completed, cooling the reaction liquid to 50°C, pouring it into deionized water for precipitation, filtering, vacuum drying at 80°C for 10 hours, and crushing it to pass through a 450-mesh sieve.
[0046] The filling composition is a combination of polyetheretherketone (PEEK), chopped aramid fiber, and aluminum borate whiskers, with a mass ratio of 10:7.5:4.5. The PEEK was purchased from Dongguan Caihua Plastic Technology Co., Ltd. as model FG9302. The chopped aramid fiber, with an average diameter of 12.5 μm and an average length of 4.5 mm, was purchased from Jiangxi Shuobang New Material Technology Co., Ltd. in China. The aluminum borate whiskers, with an aspect ratio of 20, were purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. in China.
[0047] The antioxidant is DLTDP; the light stabilizer is UV-327; the leveling agent is polyether-modified siloxane BYK-307; the defoamer is silicone defoamer BYK-037; the curing accelerator is 2-ethyl-4-methylimidazole; and the solvent is propylene glycol methyl ether acetate.
[0048] The toughening agent is carboxylated nitrile rubber, which is an industrial toughening grade product purchased from Shandong Qiyun Chemical Technology Co., Ltd. in China.
[0049] The preparation method of the above-mentioned coating adhesive for light-emitting diodes specifically includes the following steps: S1: stirring and mixing epoxy resin and functional resin at 60°C and 1000 rpm for 26 minutes, then adding a filler composition pre-dispersed with a solvent, and continuing to stir at 1400 rpm for 30 minutes; S2: adding methylhexahydrophthalic anhydride and stirring at 1000 rpm for 15 minutes, then adding an antioxidant, a light stabilizer, a leveling agent, a defoaming agent, a curing accelerator and a toughening agent in sequence, stirring at 500 rpm for 6 minutes each time, vacuum degassing for 1 hour, filtering through a 10μm nylon filter, and storing in the dark to obtain the adhesive; S3: spraying on the surface of the substrate when in use, pre-curing at 80°C for 1 hour, post-curing at 120°C for 2 hours, and final curing at 150°C for 1 hour.
[0050] Example 2
[0051] The only difference between this embodiment and embodiment 1 is as follows: Coating adhesive for light-emitting diodes, coating adhesive for light-emitting diodes, the raw materials are composed of the following components, calculated by mass: 100 parts of epoxy resin, 30 parts of functional resin, 50.5 parts of methylhexahydrophthalic anhydride, 12.2 parts of filling composition, 0.6 parts of antioxidant, 0.15 parts of light stabilizer, 0.4 parts of leveling agent, 0.2 parts of defoaming agent, 0.6 parts of curing accelerator, 5.8 parts of toughening agent, and 58 parts of solvent.
[0052] Example 3
[0053] The only difference between this embodiment and embodiment 1 is as follows: Coating adhesive for light-emitting diodes, coating adhesive for light-emitting diodes, the raw materials are composed of the following components, calculated by mass: 90 parts of epoxy resin, 25 parts of functional resin, 58.8 parts of methylhexahydrophthalic anhydride, 16 parts of filling composition, 0.6 parts of antioxidant, 0.15 parts of light stabilizer, 0.4 parts of leveling agent, 0.2 parts of defoaming agent, 0.6 parts of curing accelerator, 5.8 parts of toughening agent, and 58 parts of solvent.
[0054] Comparative Example 1
[0055] This comparative example differs from Example 1 only in the following ways: Coating adhesive for light-emitting diodes, coating adhesive for light-emitting diodes, the raw materials are composed of the following components, calculated by mass: 100 parts of epoxy resin, 6.5 parts of functional resin, 68 parts of methylhexahydrophthalic anhydride, 18.6 parts of filling composition, 0.6 parts of antioxidant, 0.15 parts of light stabilizer, 0.4 parts of leveling agent, 0.2 parts of defoaming agent, 0.6 parts of curing accelerator, 5.8 parts of toughening agent, and 58 parts of solvent.
[0056] Comparative Example 2
[0057] This comparative example differs from Example 1 only in the following ways: Coating adhesive for light-emitting diodes, coating adhesive for light-emitting diodes, the raw materials are composed of the following components, calculated by mass: 100 parts of epoxy resin, 30 parts of functional resin, 56 parts of methylhexahydrophthalic anhydride, 5 parts of filling composition, 0.6 parts of antioxidant, 0.15 parts of light stabilizer, 0.4 parts of leveling agent, 0.2 parts of defoaming agent, 0.6 parts of curing accelerator, 5.8 parts of toughening agent, and 58 parts of solvent.
[0058] Comparative Example 3
[0059] This comparative example differs from Example 1 only in the following ways: The functional resin is an epoxy-modified resin, and the preparation method specifically includes the following steps, calculated by mass: S1: adding 9.8 parts of epoxy acrylate, 1.5 parts of benzoxazine and 0.5 parts of 2-hydroxy-4-acrylate benzotriazole to 50 parts of N,N-dimethylacetamide, and stirring at 70°C and 500 rpm for 2 hours until completely uniform; S2: adding 0.14 parts of benzoyl peroxide, introducing nitrogen to replace the air, and continuing for 15 minutes, heating to 90°C and reacting for 8 hours, maintaining stirring at 200 rpm; S3: after the reaction is completed, cooling the reaction liquid to 50°C, pouring it into deionized water for precipitation, filtering, vacuum drying at 80°C for 10 hours, and crushing it to pass through a 450-mesh sieve.
[0060] Comparative Example 4
[0061] This comparative example differs from Example 1 only in the following ways: The functional resin is an epoxy-modified resin, and the preparation method specifically includes the following steps, calculated by mass: S1: adding 3.8 parts of epoxy acrylate, 4 parts of benzoxazine and 3.5 parts of 2-hydroxy-4-acrylate benzotriazole to 50 parts of N,N-dimethylacetamide, and stirring at 70°C and 500 rpm for 2 hours until completely uniform; S2: adding 0.14 parts of benzoyl peroxide, introducing nitrogen to replace the air, and continuing for 15 minutes, heating to 90°C and reacting for 8 hours, maintaining stirring at 200 rpm; S3: after the reaction is completed, cooling the reaction liquid to 50°C, pouring it into deionized water for precipitation, filtering, vacuum drying at 80°C for 10 hours, and crushing it to pass through a 450-mesh sieve.
[0062] Comparative Example 5
[0063] The only difference between this comparative example and Example 1 is that the filling composition is a composition of polyetheretherketone, chopped aramid fibers and aluminum borate whiskers, with a mass ratio of 10:3:1.
[0064] Comparative Example 6
[0065] The only differences between this comparative example and Example 1 are as follows: the average diameter of the chopped aramid fiber is 12.5 μm, the average length is 12 mm, and the corresponding size products are purchased from Jiangxi Shuobang New Material Technology Co., Ltd. in China; the aspect ratio of the aluminum borate whisker is 15, and the corresponding specification products are purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. in China.
[0066] Performance Testing
[0067] 1. Adhesion: The test refers to ASTM D1002 standard. The aluminum substrate and adhesive overlap, the overlap area is 25×12.5mm, and the adhesive layer thickness is 50μm. After curing, a universal material testing machine is used to obtain the shear strength. The results are the average of 10 tests and recorded in Table 1.
[0068] 2. Heat resistance stability: The cured adhesive layer, 2 mm thick, was cut into 25 × 25 mm squares and placed in a constant temperature oven at 200°C for 1000 h. The tensile strength was measured before and after the test, and the tensile strength retention rate was calculated. The results were averaged over 10 tests and recorded in Table 1.
[0069] 3. UV resistance: Tested using a QUV / spray UV aging chamber (UVA-340 lamp, irradiance 0.76W / m² @ 340nm), irradiated at 60°C for 8 hours, then condensed at 50°C for 4 hours, for a total of 800 hours. Yellowing index (ΔYI) was measured using a colorimeter. The average of 10 tests is reported in Table 1.
[0070] 4. Chemical resistance: The test refers to ASTM B117 standard. The aluminum substrate is coated with a rubber layer and the edges are sealed. 5% NaCl solution is sprayed continuously at 35°C for 500 hours. The bond strength before and after the test is measured and the bond strength retention rate is calculated. The results are recorded in Table 1.
[0071] Table 1 Performance test results of examples and comparative examples
[0072] Judging from the final performance test results of the embodiments and comparative examples, comparative examples 1 to 6 achieved worse performance results than the embodiments, while the embodiments, through a better technical solution, work together with a better modified resin and functional composition to form an interpenetrating network to restrict the movement of resin chain segments, significantly improving the heat deformation temperature; and on the other hand, after its addition, it absorbs energy through bridging and pull-out mechanisms, prevents crack propagation, and weakens the penetration of moisture and corrosive molecules. The electronic band structure of the whiskers converts light energy into lattice vibration energy through electron transitions, and is connected end to end in the coating to form a continuous heat conduction network, shortening the heat conduction path length, improving thermal stability while maintaining good thermal conductivity and UV and chemical resistance.
Claims
1. A coating adhesive for light-emitting diodes, characterized in that: The raw materials include, by mass, 80-110 parts of epoxy resin, 20-40 parts of functional resin, 40-60 parts of methylhexahydrophthalic anhydride, 10-20 parts of filling composition, and 50-70 parts of solvent; The functional resin is an epoxy-modified resin, and the preparation method includes: S1: adding epoxy acrylate, benzoxazine and 2-hydroxy-4-acrylate benzotriazole to N,N-dimethylacetamide; S2: adding benzoyl peroxide and heating to react; S3: after the reaction is completed, cooling the reaction solution and pouring it into deionized water for precipitation, filtering, drying, and crushing and sieving to obtain the functional resin; The mass ratio of the epoxy acrylate, benzoxazine and 2-hydroxy-4-acrylate benzotriazole is (5-7): (2-3): (1.5-2.5).
2. The coating adhesive for light emitting diodes according to claim 1, wherein: The epoxy resin is a bisphenol A epoxy resin or a bisphenol F epoxy resin; the epoxy equivalent of the epoxy resin is 160-240 g / eq.
3. The coating adhesive for light emitting diodes according to claim 2, wherein: The mass ratio of the epoxy resin, the functional resin and the methylhexahydrophthalic anhydride is (90-100): (25-30): (50-60).
4. The coating adhesive for light emitting diodes according to claim 3, wherein: The mass ratio of the epoxy resin to the filling composition is (90-100): (12-20).
5. The coating adhesive for light emitting diodes according to claim 4, wherein: The filling composition is a composition of polyetheretherketone, chopped aramid fiber and aluminum borate whisker, with a mass ratio of (9-12): (7-9): (3-5).
6. The coating adhesive for light emitting diodes according to claim 5, wherein: The average diameter of the chopped aramid fibers is 50-100 nm; the aspect ratio of the aluminum borate whiskers is 20-24.
7. The coating adhesive for light emitting diodes according to claim 6, wherein: In parts by mass, the raw materials also include: 0.6 to 1 part of antioxidant, 0.1 to 0.3 part of light stabilizer, 0.3 to 0.6 part of leveling agent, 0.1 to 0.3 part of defoaming agent, 0.5 to 0.8 part of curing accelerator, and 3 to 8 parts of toughening agent.
8. The coating adhesive for light emitting diodes according to claim 7, wherein: The light stabilizer is at least one of UV-327, UV-531, Tinuvin 622 and Tinuvin 329; the curing accelerator is at least one of 2-ethyl-4-methylimidazole, triphenylphosphine, aluminum acetylacetonate and dicumyl peroxide.
9. The coating adhesive for light emitting diodes according to claim 8, wherein: The toughening agent is carboxyl nitrile rubber or hyperbranched polyester.
10. A method for preparing the coating adhesive for light-emitting diodes according to any one of claims 1 to 9, characterized in that: S1: The epoxy resin and functional resin are stirred and mixed at 800-1000 rpm at 55-60°C for 20-30 minutes, and then the filling composition pre-dispersed with a solvent is added, and the high-speed stirring is continued at 1200-1500 rpm for 30-35 minutes; S2: Methylhexahydrophthalic anhydride is added and stirred at 800-1000 rpm for 10-15 minutes, and then antioxidant, light stabilizer, leveling agent, defoamer, curing accelerator and toughening agent are added in sequence, and each time one is added, it is stirred at 500-600 rpm for 5-7 minutes. After completion, vacuum degassing is carried out for 1-1.5 hours, and the mixture is filtered through a 10 μm nylon filter and stored away from light. S3: When used, it is sprayed on the surface of the substrate, pre-cured at 75-80°C for 1-1.5 hours, post-cured at 120-125°C for 2-2.5 hours, and finally cured at 145-150°C for 0.8-1 hour.