Cationic epoxy adhesive for electronic tri-proof and preparation method thereof

Abstract

This invention provides a cationic epoxy adhesive for electronic ruggedness and its preparation method, belonging to the field of adhesive technology. In this invention, the alicyclic epoxy resin is fluorinated and modified with silane to enhance its moisture resistance, corrosion resistance, and mechanical properties; 3-mercaptopropyltrimethoxysilane is grafted onto polydimethylsiloxane under ultraviolet light to improve its compatibility and toughness; the reaction of hyperbranched polyester with trimethyl phosphate imparts flame retardancy and metal adhesion to the material; microencapsulated slow-release curing agent solves the problem of insufficient deep curing under ultraviolet light, achieving uniform curing of both the surface and deep layers; this invention combines ultraviolet and natural curing, balancing rapid setting and deep curing, significantly optimizing the material's processing efficiency, mechanical properties, and chemical stability, meeting the diverse needs of electronic ruggedness and high-performance materials.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology and relates to a cationic epoxy adhesive for electronic protection and its preparation method. Background Technology

[0002] In the manufacturing and application of modern electronic devices, protection against mold, moisture, and salt spray is particularly important, especially when the equipment needs to operate in harsh environments for extended periods. These protective measures directly affect the reliability and lifespan of the equipment. With continuous technological advancements, the application scenarios for electronic devices are becoming increasingly diverse, including outdoor equipment, industrial automation, and military equipment, all of which place higher demands on their protective performance. Therefore, selecting suitable adhesives for the encapsulation and protection of electronic components has become a crucial issue.

[0003] Traditional epoxy adhesives are widely used for the encapsulation and protection of electronic components due to their excellent bonding strength, heat resistance, and good mechanical properties, making them the mainstream material in this field. However, despite their excellent performance in many aspects, epoxy adhesives still have some significant shortcomings in electronic conformal coating applications. First, the performance of many epoxy resins tends to degrade significantly in high humidity environments, leading to weakened bonding strength and even bonding failure. This phenomenon is particularly pronounced in humid or rainy environments, potentially causing electronic component failure and thus affecting the normal operation of the entire device.

[0004] Secondly, traditional epoxy adhesives also lack sufficient chemical resistance, failing to effectively resist the erosion of various chemical media. In certain industrial environments or outdoor applications, electronic devices may be exposed to various chemicals, such as corrosive gases, oils, or other chemical solvents. The intrusion of these chemical media can damage epoxy adhesives, thereby affecting their bonding performance and durability. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a cationic epoxy adhesive for electronic weatherproofing and its preparation method. In this invention, an alicyclic epoxy resin is modified with perfluorobutanol and KH-560 to introduce hydrophobic fluorocarbon chains and silicon-oxygen-silicon bonds, forming an organic-inorganic hybrid structure that enhances moisture resistance, corrosion resistance, thermal stability, and mechanical properties. Grafting 3-mercaptopropyltrimethoxysilane onto polydimethylsiloxane via UV-initiated reaction improves compatibility with the epoxy resin and enhances toughness and impact resistance through flexible segments. Functionalized polymers prepared by transesterification of hyperbranched polyester and trimethyl phosphate impart excellent flame retardancy, chemical stability, and metal adhesion to the material. Furthermore, a slow-release BF3-MEA curing agent is prepared using microencapsulation technology, solving the problem of insufficient UV curing depth and achieving comprehensive curing of both the surface and deep layers. This invention combines UV curing and natural curing strategies, taking into account both rapid shaping and deep curing, significantly optimizing the material's processing efficiency, mechanical properties, and chemical stability, and meeting various needs for electronic weatherproofing and high-performance materials.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a cationic epoxy adhesive for electronic protection, the method comprising:

[0008] S1: Mix alicyclic epoxy resin ERL-4221 with perfluorobutanol and react to obtain reaction solution B; add KH-560 to an ethanol / water mixture for pre-hydrolysis to obtain a silicon grafting solution, add it to reaction solution B, adjust the pH, react, and process to obtain fluorosilicone modified epoxy resin.

[0009] S2: Vinyl-terminated polydimethylsiloxane is mixed with 3-mercaptopropyltrimethoxysilane and irradiated with ultraviolet light to obtain a reaction mixture. This mixture is then mixed with n-hexane and treated to obtain modified polydimethylsiloxane. This mixture is then mixed with bisphenol F epoxy resin, reacted, and treated to obtain a crude product. This crude product is then dispersed in benzyl alcohol and rotary evaporated to obtain a toughened prepolymer.

[0010] S3: Hyperbranched polyester is mixed with trimethyl phosphate and reacted under nitrogen protection to obtain the first reaction solution. The pH is adjusted and hydrolyzed to obtain the third reaction solution. After cooling, it is poured into an ethanol / water mixed solution to precipitate and treat to obtain the phosphate polymer.

[0011] S4: Gelatin, gum arabic, and nano-silica are added to deionized water to obtain a primary wall material solution. The pH is adjusted to obtain a wall material solution. BF3-MEA complex is mixed with an ethanol / glycerol mixed solution, and the pH is adjusted to obtain a core material solution. This core material solution is mixed with the wall material solution to obtain reaction solution G. After emulsification and re-coagulation, isophorone diisocyanate and ethylenediamine are added to obtain reaction solution H. The reaction is carried out and treated to obtain microencapsulated BF3-MEA.

[0012] S5: Fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether are premixed evenly and then toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain the initial product. After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic dustproofing is obtained.

[0013] Specifically, S1: Alicyclic epoxy resin ERL-4221 is mixed with perfluorobutanol, and tetrabutylammonium bromide is added to obtain reaction solution A. The reaction solution is heated and stirred under nitrogen protection to obtain reaction solution B. KH-560 is added to an ethanol / water mixture for pre-hydrolysis to obtain a silicon grafting solution, which is added to reaction solution B to obtain a mixture. The pH is adjusted to obtain reaction solution C. The reaction is continued at a constant temperature. After filtration, washing, and vacuum drying, fluorosilicone modified epoxy resin is obtained.

[0014] S2: Vinyl-terminated polydimethylsiloxane was mixed with 3-mercaptopropyltrimethoxysilane, and photoinitiator Irgacure651 was added to obtain reaction solution D. The reaction mixture was obtained by irradiation with ultraviolet light. The mixture was then mixed with n-hexane and filtered to obtain the initial product. The initial product was washed, rotary evaporated, and dried to obtain modified polydimethylsiloxane. The modified polydimethylsiloxane was then mixed with bisphenol F epoxy resin EPON862 in toluene, and tetraphenylphosphine bromide was added to obtain reaction solution E. The mixture was reacted at a constant temperature, acid-washed, and rotary evaporated to obtain the crude product. The crude product was dispersed in benzyl alcohol and rotary evaporated again to obtain the toughened prepolymer.

[0015] S3: Hyperbranched polyester Boltorn H30 is mixed with trimethyl phosphate, potassium carbonate is added to obtain reaction solution F, reaction is carried out under nitrogen protection to obtain the first reaction solution, the pH is adjusted with hydrochloric acid to obtain the second reaction solution, hydrolysis and acidification are carried out to obtain the third reaction solution, after cooling, it is poured into an ethanol / water mixed solution for precipitation and purification, and dried to obtain the phosphate polymer.

[0016] S4: Mix gelatin and gum arabic and add to deionized water, add nano-silica to obtain a primary wall material solution, adjust the pH to obtain a wall material solution; mix BF3-MEA complex with ethanol / glycerol mixed solution and adjust the pH to obtain a core material solution; add to the wall material solution to obtain reaction solution G, emulsify to obtain an emulsion, cool and re-coagulate, then add isophorone diisocyanate and ethylenediamine to obtain reaction solution H, cross-linking reaction, centrifuge, wash and dry to obtain microencapsulated BF3-MEA;

[0017] S5: Fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether are premixed evenly and then toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain the initial product. After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic dustproofing is obtained.

[0018] As a preferred technical solution of the present invention, in step S1, the molar ratio of the alicyclic epoxy resin to perfluorobutanol is 1:0.25-0.35, for example, it can be 1:0.25, 1:0.26, 1:0.27, 1:0.28, 1:0.29, 1:0.30, 1:0.31, 1:0.32, 1:0.33, 1:0.34 or 1:0.35, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0019] In some optional embodiments, the amount of tetrabutylammonium bromide fed is 0.3-0.5% of the total mass of the alicyclic epoxy resin and perfluorobutanol, for example, it can be 0.3%, 0.32%, 0.34%, 0.36%, 0.38%, 0.40%, 0.42%, 0.44%, 0.46%, 0.48%, or 0.50%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0020] In some optional embodiments, the reaction solution A is heated to 50-60°C and stirred for reaction, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0021] In some alternative embodiments, the reaction solution A is stirred for 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours, or 3 hours, but is not limited to such values. Values ​​not mentioned in this range are also applicable.

[0022] In some optional embodiments, the mass ratio of KH-560 to the ethanol / water mixture is 1:2-3, for example, it can be 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0023] The volume ratio of ethanol to water in the ethanol / water mixture is 9:1.

[0024] In some optional embodiments, the temperature at which KH-560 is added to the ethanol / water mixture for pre-hydrolysis is 50-60°C, for example, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but other values, not referenced values ​​within this range, are also applicable.

[0025] In some optional embodiments, the KH-560 is added to the ethanol / water mixture for pre-hydrolysis for 60-70 minutes, for example, 60 minutes, 61 minutes, 62 minutes, 63 minutes, 64 minutes, 65 minutes, 66 minutes, 67 minutes, 68 minutes, 69 minutes or 70 minutes, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0026] In some optional embodiments, the amount of KH-560 fed is 10-15% of the total mass of the alicyclic epoxy resin and perfluorobutanol, for example, it can be 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0027] In some alternative embodiments, the pH of the mixture is adjusted to 5.5-6, for example, 5.5, 5.55, 5.6, 5.65, 5.7, 5.75, 5.8, 5.85, 5.9, 5.95 or 6, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0028] In some optional embodiments, the temperature of the isothermal reaction of the reaction solution C is 50-60°C, for example, it can be 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C or 60°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0029] In some optional embodiments, the reaction time of the reaction solution C at constant temperature is 1-1.5h, for example, it can be 1h, 1.05h, 1.1h, 1.15h, 1.2h, 1.25h, 1.3h, 1.35h, 1.4h, 1.45h or 1.5h, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0030] As a preferred embodiment of the present invention, in step S2, the molar ratio of the vinyl-terminated polydimethylsiloxane to 3-mercaptopropyltrimethoxysilane is 1:0.9-1.1, for example, it can be 1:0.9, 1:0.92, 1:0.94, 1:0.96, 1:0.98, 1:1, 1:1.02, 1:1.04, 1:1.06, 1:1.08 or 1:1.1, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0031] In some alternative embodiments, the photoinitiator has a mass fraction of 0.5-0.8 wt.% in the reaction solution D, for example, 0.5 wt.%, 0.53 wt.%, 0.56 wt.%, 0.59 wt.%, 0.62 wt.%, 0.65 wt.%, 0.68 wt.%, 0.71 wt.%, 0.74 wt.%, 0.77 wt.%, or 0.8 wt.%, but is not limited to such values, and values ​​not mentioned in this range also apply.

[0032] In some optional embodiments, the ultraviolet irradiation intensity of the reaction solution D is 20-25 mW / cm². 2 For example, it could be 20mW / cm 2 20.5mW / cm 2 21mW / cm 2 21.5mW / cm 2 22mW / cm 2 22.5mW / cm 2 23mW / cm 2 23.5mW / cm 2 24mW / cm 2 24.5mW / cm 2 Or 25mW / cm 2 However, it is not limited to such values; values ​​not mentioned within this range also apply.

[0033] In some alternative embodiments, the reaction solution D is irradiated with ultraviolet light for 3-5 minutes, for example, 3 minutes, 3.2 minutes, 3.4 minutes, 3.6 minutes, 3.8 minutes, 4 minutes, 4.2 minutes, 4.4 minutes, 4.6 minutes, 4.8 minutes or 5 minutes, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0034] In some alternative embodiments, the volume ratio of the reaction mixture to n-hexane is 1:3-5, for example, it can be 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0035] In some optional embodiments, the mass ratio of the modified polydimethylsiloxane to bisphenol F epoxy resin is 1:0.7-0.9, for example, it can be 1:0.7, 1:0.72, 1:0.74, 1:0.76, 1:0.78, 1:0.8, 1:0.82, 1:0.84, 1:0.86, 1:0.88 or 1:0.9, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0036] In some optional embodiments, the total mass fraction of the modified polydimethylsiloxane and bisphenol F epoxy resin in toluene is 15-20 wt.%, for example, it can be 15 wt.%, 15.5 wt.%, 16 wt.%, 16.5 wt.%, 17 wt.%, 17.5 wt.%, 18 wt.%, 18.5 wt.%, 19 wt.%, 19.5 wt.%, or 20 wt.%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0037] In some optional embodiments, the amount of tetraphenylphosphine bromide fed is 0.05-0.1% of the total mass of the modified polydimethylsiloxane and bisphenol F epoxy resin, for example, it can be 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095% or 0.1%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0038] In some optional embodiments, the temperature of the isothermal reaction in the reaction solution E is 120-125°C, for example, it can be 120°C, 120.5°C, 121°C, 121.5°C, 122°C, 122.5°C, 123°C, 123.5°C, 124°C, 124.5°C or 125°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0039] In some optional embodiments, the reaction time of the reaction solution E at a constant temperature is 2-2.5h, for example, it can be 2h, 2.05h, 2.1h, 2.15h, 2.2h, 2.25h, 2.3h, 2.35h, 2.4h, 2.45h or 2.5h, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0040] The pickling process uses 0.1M hydrochloric acid.

[0041] In some optional embodiments, the amount of benzyl alcohol added is 30-40% of the mass of the crude product, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0042] As a preferred technical solution of the present invention, in step S3, the molar ratio of the hyperbranched polyester to trimethyl phosphate is 1:1.1-1.3, for example, it can be 1:1.1, 1:1.2, 1:1.14, 1:1.16, 1:1.18, 1:1.2, 1:1.22, 1:1.24, 1:1.26, 1:1.28 or 1:1.3, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0043] In some alternative embodiments, the amount of potassium carbonate fed is 1.5-2.5% of the total mass of the hyperbranched polyester and trimethyl phosphate, for example, it can be 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4% or 2.5%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0044] In some optional embodiments, the reaction liquid F is reacted at a temperature of 120-130°C under nitrogen protection, for example, 120°C, 121°C, 122°C, 123°C, 124°C, 125°C, 126°C, 127°C, 128°C, 129°C or 130°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0045] In some optional embodiments, the reaction liquid F is reacted under nitrogen protection for 7-8 hours, for example, 7 hours, 7.1 hours, 7.2 hours, 7.3 hours, 7.4 hours, 7.5 hours, 7.6 hours, 7.7 hours, 7.8 hours, 7.9 hours or 8 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0046] In some alternative embodiments, the concentration of the hydrochloric acid is 0.1-0.2M, for example, 0.1M, 0.11M, 0.12M, 0.13M, 0.14M, 0.15M, 0.16M, 0.17M, 0.18M, ​​0.19M or 0.2M, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0047] In some alternative embodiments, the pH of the first reaction solution is adjusted to 2.8-3 using hydrochloric acid, for example, 2.8, 2.82, 2.84, 2.86, 2.88, 2.9, 2.92, 2.94, 2.96, 2.98 or 3, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0048] In some alternative embodiments, the hydrolysis and acidification temperature of the second reaction solution is 60-65°C, for example, 60°C, 60.5°C, 61°C, 61.5°C, 62°C, 62.5°C, 63°C, 63.5°C, 64°C, 64.5°C or 65°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0049] In some alternative embodiments, the hydrolysis and acidification time of the second reaction solution is 2-3 hours, for example, 2 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0050] In some alternative embodiments, the volume ratio of the third reaction solution to the ethanol / water mixture is 1:5-6, for example, it can be 1:5, 1:5.1, 1:5.2, 1:5.3, 1:5.4, 1:5.5, 1:5.6, 1:5.7, 1:5.8, 1:5.9 or 1:6, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0051] The volume ratio of ethanol to water in the ethanol / water mixed solution is 7:3.

[0052] As a preferred embodiment of the present invention, in step S4, the mass ratio of gelatin to gum arabic is 1:1.

[0053] In some alternative embodiments, the total mass fraction of the gelatin and gum arabic in deionized water is 5-10 wt.%, for example, it can be 5 wt.%, 5.5 wt.%, 6 wt.%, 6.5 wt.%, 7 wt.%, 7.5 wt.%, 8 wt.%, 8.5 wt.%, 9 wt.%, 9.5 wt.%, or 10 wt.%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0054] In some alternative embodiments, the mass fraction of the nano-silica in the primary wall material solution is 1-2 wt.%, for example, it can be 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.4 wt.%, 1.5 wt.%, 1.6 wt.%, 1.7 wt.%, 1.8 wt.%, 1.9 wt.%, or 2 wt.%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0055] In some alternative embodiments, the pH of the primary wall material solution is adjusted to 4.3-4.7, for example, 4.3, 4.34, 4.38, 4.42, 4.46, 4.5, 4.54, 4.58, 4.62, 4.66 or 4.7, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0056] The volume ratio of ethanol to glycerol in the ethanol / glycerol mixed solution is 8:2;

[0057] In some alternative embodiments, the mass ratio of the BF3-MEA complex to the ethanol / glycerol mixed solution is 1:2-2.5, for example, it can be 1:2, 1:2.05, 1:2.1, 1:2.15, 1:2.2, 1:2.25, 1:2.3, 1:2.35, 1:2.4, 1:2.45 or 1:2.5, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0058] In some alternative embodiments, the pH of the BF3-MEA complex is adjusted to 2.8-3.2 after mixing with the ethanol / glycerol mixture, for example, 2.8, 2.84, 2.88, 2.92, 2.96, 3.0, 3.04, 3.08, 3.12, 3.16 or 3.2, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0059] In some optional embodiments, the mass ratio of the BF3-MEA complex to the total mass of gelatin and gum arabic is 1:1.8-2.2, for example, it can be 1:1.8, 1:1.84, 1:1.88, 1:1.92, 1:1.96, 1:2.0, 1:2.04, 1:2.08, 1:2.12, 1:2.16 or 1:2.2, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0060] In some alternative embodiments, the reaction solution G is emulsified at a temperature of 45-50°C, for example, 45°C, 45.5°C, 46°C, 46.5°C, 47°C, 47.5°C, 48°C, 48.5°C, 49°C, 49.5°C, or 50°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0061] In some alternative embodiments, the emulsification time of the reaction solution G is 5-8 min, for example, 5 min, 5.3 min, 5.6 min, 5.9 min, 6.2 min, 6.5 min, 6.8 min, 7.1 min, 7.4 min, 7.7 min or 8 min, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0062] In some alternative embodiments, the emulsion is cooled to 8-12°C for re-coagulation, for example, 8°C, 8.4°C, 8.8°C, 9.2°C, 9.6°C, 10°C, 10.4°C, 10.8°C, 11.2°C, 11.6°C, or 12°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0063] In some alternative embodiments, the emulsion re-coagulation time is 1.5-2 hours, for example, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours or 2 hours, but is not limited to such values, and values ​​not mentioned in this range also apply.

[0064] In some optional embodiments, the amount of isophorone diisocyanate fed is 4-6% of the mass of the BF3-MEA complex, for example, it can be 4%, 4.2%, 4.4%, 4.6%, 4.8%, 5%, 5.2%, 5.4%, 5.6%, 5.8% or 6%, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0065] In some alternative embodiments, the molar ratio of ethylenediamine to isophorone diisocyanate is 1.1-1.2:1, for example, it can be 1.1:1, 1.11:1, 1.12:1, 1.13:1, 1.14:1, 1.15:1, 1.16:1, 1.17:1, 1.18:1, 1.19:1 or 1.2:1, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0066] In some alternative embodiments, the crosslinking reaction temperature of the reaction solution H is 45-50°C, for example, 45°C, 45.5°C, 46°C, 46.5°C, 47°C, 47.5°C, 48°C, 48.5°C, 49°C, 49.5°C or 50°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0067] In some alternative embodiments, the crosslinking reaction time of the reaction solution H is 3-4 hours, for example, 3 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours or 4 hours, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0068] As a preferred technical solution of the present invention, in step S5, the premixing temperature of the fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether is 40-45°C, for example, 40°C, 40.5°C, 41°C, 41.5°C, 42°C, 42.5°C, 43°C, 43.5°C, 44°C, 44.5°C, or 45°C, but is not limited to such values, and values ​​not mentioned in this range are also applicable.

[0069] The mass ratio of the fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, 1,4-cyclohexanediethanol diglycidyl ether, toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA and leveling agent FC-4430 is (28-32):(18-22):(15-20):(6-8):(7-9):(3.5-4.5):(0.5-1):(3-4):(0.3-0.4).

[0070] Secondly, the present invention provides a cationic epoxy adhesive for electronic protection prepared by the above-described preparation method.

[0071] This invention selects alicyclic epoxy resin as the matrix resin primarily based on its superior performance characteristics and structural advantages. Alicyclic epoxy resins possess a rigid cyclic backbone, a structure that endows the material with a high glass transition temperature and excellent mechanical properties. Simultaneously, its molecular structure provides good chemical resistance, low hygroscopicity, and thermal stability. Furthermore, the epoxy groups on alicyclic epoxy resins are active sites for cationic polymerization, enabling the formation of a dense cross-linked network through cationic ring-opening polymerization during curing, thereby significantly improving the material's strength and stability.

[0072] To further enhance the functional properties of alicyclic epoxy resins, perfluorobutanol is introduced for modification in this invention. Perfluorobutanol molecules contain hydroxyl groups and highly hydrophobic fluorocarbon chains. The hydroxyl groups can undergo ring-opening reactions with the epoxy groups of alicyclic epoxy resins. Under the catalysis of tetrabutylammonium bromide, the hydroxyl groups of perfluorobutanol nucleophilically attack the epoxy groups to form ether bonds, while simultaneously introducing the fluorocarbon chains stably into the resin molecular structure. The introduction of fluorinated groups reduces the surface energy of the modified resin, thereby enhancing the material's moisture resistance and corrosion resistance, meeting the requirements for electronic dust resistance. Furthermore, by optimizing the reaction conditions, excessive ring-opening reactions of the epoxy groups are effectively avoided, ensuring a sufficiently high crosslinking density and excellent mechanical properties during subsequent curing.

[0073] After fluorination modification, this invention further introduces KH-560 to silane modify the alicyclic epoxy resin to optimize its overall performance. KH-560 undergoes partial hydrolysis in an ethanol / water system, converting the trimethoxysilane group into silanol. Subsequently, the silanol forms silicon-oxygen-silicon bonds through a condensation reaction. Simultaneously, the silanol undergoes a ring-opening reaction with the alicyclic epoxy resin to form silicon-oxygen-carbon bonds. This coupling effect constructs an organic-inorganic hybrid structure at the molecular level.

[0074] The introduction of silicon grafting significantly improves the performance of modified epoxy resins in several aspects: the silicon-oxygen-silicon bond has high bond energy, and its introduction significantly improves the thermal stability of the modified resin, enabling it to withstand long-term use in higher temperature environments; secondly, KH-560, as a silane coupling agent, has a molecular structure that combines inorganic silicon-oxygen bonds and organic epoxy groups, which can enhance the interfacial bonding between the modified resin and the substrate through chemical bonding; in addition, the siloxane segments have high flexibility, which can significantly alleviate the internal stress generated during the curing process due to the high crosslinking density, thereby reducing interfacial cracks and warping, and improving the mechanical properties and durability of the material.

[0075] This invention achieves highly efficient grafting of vinyl-terminated polydimethylsiloxane and 3-mercaptopropyltrimethoxysilane through a UV-initiated chemical reaction. Specifically, under the action of a UV photoinitiator, the vinyl groups of vinyl-terminated polydimethylsiloxane are excited by UV light to generate active free radicals. These free radicals can rapidly initiate an addition reaction between the mercapto groups of 3-mercaptopropyltrimethoxysilane and the vinyl groups, forming carbon-sulfur bonds. This allows for the grafting of 3-mercaptopropyltrimethoxysilane onto the polydimethylsiloxane chain, generating a polydimethylsiloxane-silane copolymer. Through this reaction, the polydimethylsiloxane segment introduces a flexible silicon-oxygen-silicon structure while also introducing active siloxy groups through 3-mercaptopropyltrimethoxysilane, providing active sites for subsequent chemical bonding with epoxy resins.

[0076] The introduction of flexible polydimethylsiloxane (PDMS) segments plays a crucial role in the toughness and impact resistance of adhesives. The main chain of PDMS is composed of silicon-oxygen-silicon bonds, giving it high flexibility and low modulus. These flexible segments effectively alleviate stress concentration and absorb impact loads, significantly improving the adhesive's impact resistance and elongation at break. Furthermore, unmodified PDMS, due to its high hydrophobicity, exhibits significant interfacial incompatibility with highly polar epoxy resins, easily leading to phase separation during curing and resulting in decreased material properties. Therefore, chemical modification to introduce siloxane groups enables PDMS to react chemically with epoxy resins, thus resolving the compatibility issue.

[0077] Under the catalysis of tetraphenylphosphine bromide, modified polydimethylsiloxane can react with the epoxy groups of bisphenol F epoxy resin through its siloxy groups. Under the action of the catalyst, the epoxy groups undergo a ring-opening reaction, forming silicon-oxygen-carbon bonds with the siloxy groups, thus achieving chemical bonding between the two molecules. This chemical bonding embeds flexible polydimethylsiloxane segments into the cross-linked network of the epoxy resin at the molecular level, forming a covalently linked organic-inorganic hybrid structure. The low viscosity of bisphenol F epoxy resin helps to uniformly disperse the modified polydimethylsiloxane, avoiding localized unevenness during mixing. Its high cross-linking density, combined with the flexible polydimethylsiloxane segments, forms a uniform and dense network structure in the material, improving both the strength and heat resistance of the material, and effectively alleviating the internal stress caused by the high cross-linking density through the dispersion of the flexible segments.

[0078] This invention successfully prepared a functionalized polymer containing high-density phosphate ester bonds and phosphonic acid groups by designing a transesterification reaction between hyperbranched polyester and trimethyl phosphate. Under the catalysis of potassium carbonate, the hydroxyl groups in the hyperbranched polyester undergo a transesterification reaction with the ester groups in trimethyl phosphate to generate phosphate ester bonds. This process ensures that the phosphate ester groups are uniformly distributed in the molecular structure of the hyperbranched polyester while preserving the multi-branched structure of the hyperbranched molecule. Subsequently, through acidic hydrolysis, some of the phosphate ester bonds are hydrolyzed, releasing phosphonic acid groups, further endowing the material with specific functional properties.

[0079] The introduction of hyperbranched structure is one of the key design features of this invention. Hyperbranched polyesters possess a highly branched three-dimensional structure with a large number of active groups distributed both internally and on the surface of the molecule, enabling them to provide an extremely high functional group density. This high density of phosphate ester bonds endows the material with excellent flame retardant properties. Furthermore, the phosphate ester bonds and phosphonic acid groups exhibit good chemical stability, which can significantly improve the material's corrosion resistance, especially in high humidity or corrosive environments, where the material demonstrates excellent durability.

[0080] On the other hand, the introduction of phosphonic acid groups further enhances the adhesion of the material to the metal surface. Phosphonic acid groups have a strong ability to form chemical bonds with the metal surface, and can form stable interfacial bonds through chemical adsorption or coordination with the metal oxide layer. This bond not only firmly connects the adhesive to the metal surface but also effectively improves peel strength, ensuring the reliability of the material in complex environments.

[0081] This invention prepares a slow-release BF3-MEA curing agent using microencapsulation technology, effectively controlling the catalyst release process and optimizing the curing performance of the epoxy system. Specifically, gelatin and gum arabic are used as wall materials, and a stable wall material structure is initially formed through their electrostatic interaction. Gelatin contains cationic groups, while gum arabic contains anionic groups; under suitable pH conditions, they can form a uniform initial wall material solution through electrostatic attraction. Based on this, a low-temperature re-coagulation process is used to further aggregate and precipitate the wall material in an aqueous solution, coating the core material BF3-MEA complex to form a microcapsule structure with preliminary mechanical strength. Nano-silica enhances the compactness of the microcapsule wall and reduces water permeability through physical filling and interaction with surface hydroxyl groups.

[0082] To further enhance the mechanical properties and environmental stability of the microcapsules, this invention designs a cross-linking reaction. Isophorone diisocyanate undergoes an addition reaction with the amino groups and ethylenediamine in the wall material to generate a three-dimensional cross-linked polyurea network. This improves the strength and durability of the microcapsules while maintaining their sustained-release capability. The cross-linked polyurea network forms a dense protective layer on the microcapsule surface, effectively preventing premature release of the BF3-MEA complex in the core material during storage or processing, ensuring its latency.

[0083] Microencapsulated BF3-MEA plays a crucial role in the UV post-curing stage of epoxy systems. In the initial curing phase, UV-induced cationic polymerization primarily targets surface epoxy groups, forming a preliminary cured structure. However, due to the limited penetration depth of UV curing, the curing effect on deeper epoxy groups is often incomplete. At this point, microencapsulated BF3-MEA gradually releases BF3-MEA complexes under heating conditions. BF3, as a strong cationic catalyst, effectively promotes the ring-opening polymerization reaction of epoxy groups, further enhancing the degree of deep curing and crosslinking density. This slow-release mechanism ensures uniform curing of the epoxy system from the surface to the depths, improving the overall physical properties and chemical stability of the material.

[0084] In this application, comprehensive cross-linking of surface and deep epoxy groups is achieved through UV curing and natural curing. UV curing is responsible for rapid shaping and surface curing, while natural curing completes the deep curing reaction through the slow-release catalyst. The two complement each other in time and space, which not only improves processing efficiency but also ensures the mechanical properties, chemical stability, and deep curing effect of the material.

[0085] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0086] This invention uses alicyclic epoxy resin as a matrix, where the epoxy groups form a dense cross-linked network through cationic polymerization, enhancing strength and chemical stability. Perfluorobutanol modification introduces hydrophobic fluorocarbon chains into the resin molecules, reducing surface energy and significantly enhancing moisture and corrosion resistance. Further silanization modification using KH-560 silane coupling agent introduces silicon-oxygen-silicon bonds to form an organic-inorganic hybrid structure, improving thermal stability, interfacial bonding, and flexibility. This improves internal stress and optimizes mechanical properties and durability, meeting the high-performance requirements of electronic ruggedness.

[0087] This invention utilizes a UV-initiated reaction to graft 3-mercaptopropyltrimethoxysilane onto vinyl-terminated polydimethylsiloxane, generating a copolymer containing active siloxy groups, thus resolving its compatibility issue with epoxy resins. After modification, the polydimethylsiloxane chemically bonds to bisphenol F epoxy resin through siloxy groups, forming an organic-inorganic hybrid network. The flexible silicon-oxygen-silicon segments significantly improve toughness and impact resistance while mitigating internal stress. The high crosslinking density of the network further enhances the material's strength and heat resistance, achieving a comprehensive performance of high toughness and high strength.

[0088] This invention prepares a functionalized polymer containing high-density phosphate ester bonds and phosphonic acid groups through a transesterification reaction of hyperbranched polyester and trimethyl phosphate. The hyperbranched structure provides a high functional group density, endowing the material with excellent flame retardant properties and chemical stability, while the phosphate ester bonds synergistically inhibit flame propagation through the condensed phase and gas phase. Simultaneously, the phosphonic acid groups enhance the material's adhesion to metal surfaces, forming stable chemical bonds with the metal oxide layer, improving interfacial bonding and peel strength, and significantly enhancing the material's durability and reliability in high humidity and corrosive environments.

[0089] This invention prepares a sustained-release BF3-MEA curing agent using microencapsulation technology. A stable wall material is formed using gelatin and gum arabic, and the strength and sustained-release properties of the microcapsules are enhanced through polyurea crosslinking. The microencapsulated BF3-MEA is gradually released during the UV post-curing stage, solving the problem of insufficient UV curing depth. It uniformly promotes the ring-opening polymerization of epoxy groups, achieving complete curing from the surface to the depths, and significantly improving the mechanical properties and chemical stability of the material.

[0090] In this application, comprehensive cross-linking of surface and deep epoxy groups is achieved through UV curing and natural curing. UV curing is responsible for rapid shaping and surface curing, while natural curing completes the deep curing reaction through the slow-release catalyst. The two complement each other in time and space, which not only improves processing efficiency but also ensures the mechanical properties, chemical stability, and deep curing effect of the material. Detailed Implementation

[0091] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0092] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0093] Example 1

[0094] This embodiment provides a cationic epoxy adhesive for electronic weather protection and its preparation method. The preparation method of the cationic epoxy adhesive for electronic weather protection specifically includes the following steps:

[0095] S1: Alicyclic epoxy resin ERL-4221 and perfluorobutanol were mixed at a molar ratio of 1:0.3. Tetrabutylammonium bromide was added to obtain reaction solution A, wherein the amount of tetrabutylammonium bromide added was 0.4% of the total mass of the alicyclic epoxy resin and perfluorobutanol. The mixture was heated to 50℃ under nitrogen protection and stirred for 2.5h to obtain reaction solution B. KH-560 was added to an ethanol / water mixture and pre-hydrolyzed at 50℃ for 65min to obtain a silicon grafting solution, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 9:1 and the mass ratio of KH-560 to anhydrous ethanol was 1:2.5. This solution was added to reaction solution B to obtain a mixture, wherein the amount of KH-560 added was 12% of the total mass of the alicyclic epoxy resin and perfluorobutanol. The pH was adjusted to 5.8 to obtain reaction solution C. The mixture was reacted at a constant temperature of 50℃ for 1.2h. After filtration, washing, and vacuum drying, fluorosilicone modified epoxy resin was obtained.

[0096] S2: Vinyl-terminated polydimethylsiloxane and 3-mercaptopropyltrimethoxysilane were mixed at a molar ratio of 1:1, and photoinitiator Irgacure 651 was added to obtain reaction solution D, wherein the mass fraction of photoinitiator in reaction solution D was 0.65 wt.%. The mixture was irradiated with ultraviolet light for 4 min to obtain a reaction mixture, wherein the irradiation intensity of ultraviolet light on reaction solution D was 24 mW / cm². 2 The modified polydimethylsiloxane was mixed with n-hexane at a volume ratio of 1:3, filtered to obtain a primary product, washed, rotary evaporated, and dried to obtain a modified polydimethylsiloxane. This modified polydimethylsiloxane was then mixed with bisphenol F epoxy resin EPON862 at a mass ratio of 1:0.8 in toluene, wherein the total mass fraction of the modified polydimethylsiloxane and bisphenol F epoxy resin in toluene was 18 wt.%. Tetraphenylphosphine bromide was added to obtain reaction solution E, wherein the amount of tetraphenylphosphine bromide added was 0.08% of the total mass of the modified polydimethylsiloxane and bisphenol F epoxy resin. The reaction was carried out at a constant temperature of 120℃ for 2.4 h. The mixture was then acid-washed with 0.1 M hydrochloric acid and rotary evaporated to obtain a crude product, which was dispersed in benzyl alcohol, wherein the amount of benzyl alcohol added was 30% of the mass of the crude product. Further rotary evaporation was performed to obtain a toughened prepolymer.

[0097] S3: Hyperbranched polyester Boltorn H30 and trimethyl phosphate were mixed at a molar ratio of 1:1.2, and potassium carbonate was added to obtain reaction solution F, wherein the amount of potassium carbonate added was 2% of the total mass of hyperbranched polyester and trimethyl phosphate. The reaction was carried out at 125°C for 7 hours under nitrogen protection to obtain the first reaction solution. The pH was adjusted to 2.9 with 0.15M hydrochloric acid to obtain the second reaction solution. The reaction solution was hydrolyzed and acidified at 60°C for 2 hours to obtain the third reaction solution. After cooling, the solution was poured into an ethanol / water mixture for precipitation and purification, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 7:3, and the volume ratio of the third reaction solution to the ethanol / water mixture was 1:5.5. The solution was dried to obtain the phosphate polymer.

[0098] S4: Gelatin and gum arabic are mixed at a mass ratio of 1:1 and added to deionized water, where the total mass fraction of gelatin and gum arabic in the deionized water is 8 wt.%. Nano-silica is added to obtain a primary wall material solution, where the mass fraction of nano-silica in the primary wall material solution is 1.5 wt.%. The pH is adjusted to 4.3 to obtain a wall material solution. BF3-MEA complex is mixed with an ethanol / glycerol mixed solution at a mass ratio of 1:2.3, where the volume ratio of ethanol to glycerol in the ethanol / glycerol mixed solution is 8:2. The pH is adjusted to 3 to obtain a core material solution. This is then added to... Reaction solution G was obtained by adding BF3-MEA complex to the wall material solution, wherein the mass ratio of BF3-MEA complex to gelatin and gum arabic was 1:2. The emulsion was obtained by emulsification at 45℃ for 5 min, and then cooled to 10℃ for re-coagulation for 1.5 h. Subsequently, isophorone diisocyanate and ethylenediamine were added to obtain reaction solution H, wherein the amount of isophorone diisocyanate added was 5% of the mass of BF3-MEA complex, and the molar ratio of ethylenediamine to isophorone diisocyanate was 1.15:1. The crosslinking reaction was carried out at 45℃ for 3.5 h. After centrifugation, washing and drying, microencapsulated BF3-MEA was obtained.

[0099] S5: Fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether are premixed uniformly at 44℃, and then toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain a primary product. After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic dustproofing is obtained. The mass ratio of fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, 1,4-cyclohexanediethanol diglycidyl ether, toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 is 30:20:17:7:8:4:0.8:3.5:0.37.

[0100] Example 2

[0101] This embodiment provides a cationic epoxy adhesive for electronic weather protection and its preparation method. The preparation method of the cationic epoxy adhesive for electronic weather protection specifically includes the following steps:

[0102] S1: Alicyclic epoxy resin ERL-4221 and perfluorobutanol were mixed at a molar ratio of 1:0.32. Tetrabutylammonium bromide was added to obtain reaction solution A, wherein the amount of tetrabutylammonium bromide added was 0.3% of the total mass of the alicyclic epoxy resin and perfluorobutanol. The mixture was heated to 55℃ under nitrogen protection and stirred for 2 hours to obtain reaction solution B. KH-560 was added to an ethanol / water mixture and pre-hydrolyzed at 60℃ for 60 minutes to obtain a silicon grafting solution, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 9:1 and the mass ratio of KH-560 to anhydrous ethanol was 1:2. This solution was added to reaction solution B to obtain a mixture, wherein the amount of KH-560 added was 15% of the total mass of the alicyclic epoxy resin and perfluorobutanol. The pH was adjusted to 5.7 to obtain reaction solution C. The mixture was reacted at a constant temperature of 60℃ for 1.4 hours. After filtration, washing, and vacuum drying, fluorosilicone modified epoxy resin was obtained.

[0103] S2: Vinyl-terminated polydimethylsiloxane and 3-mercaptopropyltrimethoxysilane were mixed at a molar ratio of 1:1.05, and photoinitiator Irgacure 651 was added to obtain reaction solution D, wherein the mass fraction of photoinitiator in reaction solution D was 0.7 wt.%. The mixture was irradiated with ultraviolet light for 3 min to obtain a reaction mixture, wherein the irradiation intensity of ultraviolet light on reaction solution D was 20 mW / cm². 2 The modified polydimethylsiloxane was mixed with n-hexane at a volume ratio of 1:4, filtered to obtain a primary product, washed, rotary evaporated, and dried to obtain a modified polydimethylsiloxane. This modified polydimethylsiloxane was then mixed with bisphenol F epoxy resin EPON862 at a mass ratio of 1:0.84 in toluene, wherein the total mass fraction of the modified polydimethylsiloxane and bisphenol F epoxy resin in toluene was 17 wt.%. Tetraphenylphosphine bromide was added to obtain reaction solution E, wherein the amount of tetraphenylphosphine bromide added was 0.07% of the total mass of the modified polydimethylsiloxane and bisphenol F epoxy resin. The reaction was carried out at a constant temperature of 122℃ for 2.3 h. The mixture was then acid-washed with 0.1M hydrochloric acid and rotary evaporated to obtain a crude product, which was dispersed in benzyl alcohol, wherein the amount of benzyl alcohol added was 35% of the mass of the crude product. Further rotary evaporation was performed to obtain a toughened prepolymer.

[0104] S3: Hyperbranched polyester Boltorn H30 and trimethyl phosphate were mixed at a molar ratio of 1:1.25, and potassium carbonate was added to obtain reaction solution F, wherein the amount of potassium carbonate added was 2.2% of the total mass of hyperbranched polyester and trimethyl phosphate. The reaction was carried out at 128°C for 7.6 h under nitrogen protection to obtain the first reaction solution. The pH was adjusted to 2.85 with 0.18M hydrochloric acid to obtain the second reaction solution. The reaction solution was hydrolyzed and acidified at 62°C for 2.5 h to obtain the third reaction solution. After cooling, the solution was poured into an ethanol / water mixed solution for precipitation and purification, wherein the volume ratio of ethanol to water in the ethanol / water mixed solution was 7:3, and the volume ratio of the third reaction solution to the ethanol / water mixed solution was 1:5. The solution was dried to obtain the phosphate polymer.

[0105] S4: Gelatin and gum arabic are mixed at a mass ratio of 1:1 and added to deionized water, wherein the total mass fraction of gelatin and gum arabic in deionized water is 7 wt.%. Nano-silica is added to obtain a primary wall material solution, wherein the mass fraction of nano-silica in the primary wall material solution is 1.8 wt.%. The pH is adjusted to 4.5 to obtain a wall material solution. BF3-MEA complex is mixed with an ethanol / glycerol mixed solution at a mass ratio of 1:2.2, wherein the volume ratio of ethanol to glycerol in the ethanol / glycerol mixed solution is 8:2, and the pH is adjusted to 3.1 to obtain a core material solution. This is then added to... Reaction solution G was obtained by adding BF3-MEA complex to the wall material solution, wherein the mass ratio of BF3-MEA complex to gelatin and gum arabic was 1:2.1. The emulsion was emulsified at 47℃ for 7 min to obtain an emulsion, which was then cooled to 11℃ and allowed to re-coagulate for 1.6 h. Subsequently, isophorone diisocyanate and ethylenediamine were added to obtain reaction solution H, wherein the amount of isophorone diisocyanate added was 5.5% of the mass of BF3-MEA complex, and the molar ratio of ethylenediamine to isophorone diisocyanate was 1.18:1. The crosslinking reaction was carried out at 48℃ for 4 h, and the microencapsulated BF3-MEA was obtained by centrifugation, washing, and drying.

[0106] S5: Fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether are premixed uniformly at 43°C, and then toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain a primary product. After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic dustproofing is obtained. The mass ratio of fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, 1,4-cyclohexanediethanol diglycidyl ether, toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 is 29:21:18:6:8.5:3.5:0.5:3.8:0.3.

[0107] Example 3

[0108] This embodiment provides a cationic epoxy adhesive for electronic weather protection and its preparation method. The preparation method of the cationic epoxy adhesive for electronic weather protection specifically includes the following steps:

[0109] S1: Alicyclic epoxy resin ERL-4221 and perfluorobutanol were mixed at a molar ratio of 1:0.25. Tetrabutylammonium bromide was added to obtain reaction solution A, wherein the amount of tetrabutylammonium bromide added was 0.42% of the total mass of alicyclic epoxy resin and perfluorobutanol. The mixture was heated to 58℃ under nitrogen protection and stirred for 3 hours to obtain reaction solution B. KH-560 was added to an ethanol / water mixture and pre-hydrolyzed at 55℃ for 68 minutes to obtain a silicon grafting solution, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 9:1 and the mass ratio of KH-560 to anhydrous ethanol was 1:3. This solution was added to reaction solution B to obtain a mixture, wherein the amount of KH-560 added was 10% of the total mass of alicyclic epoxy resin and perfluorobutanol. The pH was adjusted to 5.5 to obtain reaction solution C. The mixture was reacted at a constant temperature of 58℃ for 1 hour. After filtration, washing, and vacuum drying, fluorosilicone modified epoxy resin was obtained.

[0110] S2: Vinyl-terminated polydimethylsiloxane and 3-mercaptopropyltrimethoxysilane were mixed at a molar ratio of 1:0.9, and photoinitiator Irgacure 651 was added to obtain reaction solution D, wherein the mass fraction of photoinitiator in reaction solution D was 0.5 wt.%. The mixture was irradiated with ultraviolet light for 4.2 min to obtain a reaction mixture, wherein the irradiation intensity of ultraviolet light on reaction solution D was 22 mW / cm². 2 The modified polydimethylsiloxane was mixed with n-hexane at a volume ratio of 1:4.2, filtered to obtain a primary product, washed, rotary evaporated, and dried to obtain a modified polydimethylsiloxane. This modified polydimethylsiloxane was then mixed with bisphenol F epoxy resin EPON862 at a mass ratio of 1:0.7 in toluene, wherein the total mass fraction of the modified polydimethylsiloxane and bisphenol F epoxy resin in toluene was 15 wt.%. Tetraphenylphosphine bromide was added to obtain reaction solution E, wherein the amount of tetraphenylphosphine bromide added was 0.05% of the total mass of the modified polydimethylsiloxane and bisphenol F epoxy resin. The reaction was carried out at a constant temperature of 124℃ for 2 hours, and then acid-washed with 0.1M hydrochloric acid and rotary evaporated to obtain a crude product. This crude product was dispersed in benzyl alcohol, wherein the amount of benzyl alcohol added was 40% of the mass of the crude product. Further rotary evaporation was performed to obtain a toughened prepolymer.

[0111] S3: Hyperbranched polyester Boltorn H30 and trimethyl phosphate were mixed at a molar ratio of 1:1.1, and potassium carbonate was added to obtain reaction solution F, wherein the amount of potassium carbonate added was 1.5% of the total mass of hyperbranched polyester and trimethyl phosphate. The reaction was carried out at 120°C for 7.7 h under nitrogen protection to obtain the first reaction solution. The pH was adjusted to 2.8 with 0.1M hydrochloric acid to obtain the second reaction solution. The reaction solution was hydrolyzed and acidified at 64°C for 2.8 h to obtain the third reaction solution. After cooling, the solution was poured into an ethanol / water mixture for precipitation and purification, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 7:3, and the volume ratio of the third reaction solution to the ethanol / water mixture was 1:6. The solution was dried to obtain the phosphate polymer.

[0112] S4: Gelatin and gum arabic are mixed at a mass ratio of 1:1 and added to deionized water, wherein the total mass fraction of gelatin and gum arabic in deionized water is 5 wt.%. Nano-silica is added to obtain a primary wall material solution, wherein the mass fraction of nano-silica in the primary wall material solution is 1 wt.%. The pH is adjusted to 4.6 to obtain a wall material solution. BF3-MEA complex and ethanol / glycerol mixed solution are mixed at a mass ratio of 1:2, wherein the volume ratio of ethanol to glycerol in the ethanol / glycerol mixed solution is 8:2, and the pH is adjusted to 2.8 to obtain a core material solution. This is then added to... Reaction solution G was obtained by adding BF3-MEA complex to the wall material solution, wherein the mass ratio of BF3-MEA complex to gelatin and gum arabic was 1:1.8. The emulsion was obtained by emulsification at 48℃ for 6 min, and then cooled to 8℃ for re-coagulation for 1.8 h. Subsequently, isophorone diisocyanate and ethylenediamine were added to obtain reaction solution H, wherein the amount of isophorone diisocyanate added was 4% of the mass of BF3-MEA complex, and the molar ratio of ethylenediamine to isophorone diisocyanate was 1.1:1. The crosslinking reaction was carried out at 47℃ for 3 h. After centrifugation, washing and drying, microencapsulated BF3-MEA was obtained.

[0113] S5: Fluorosilicone-modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether are premixed uniformly at 40°C, and then toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain a primary product. After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic dustproofing is obtained. The mass ratio of fluorosilicone-modified epoxy resin, bisphenol F epoxy resin EPON862, 1,4-cyclohexanediethanol diglycidyl ether, toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 is 28:18:15:7.4:7:4.5:0.7:3:0.36.

[0114] Example 4

[0115] This embodiment provides a cationic epoxy adhesive for electronic weather protection and its preparation method. The preparation method of the cationic epoxy adhesive for electronic weather protection specifically includes the following steps:

[0116] S1: Alicyclic epoxy resin ERL-4221 and perfluorobutanol were mixed at a molar ratio of 1:0.35. Tetrabutylammonium bromide was added to obtain reaction solution A, wherein the amount of tetrabutylammonium bromide added was 0.5% of the total mass of alicyclic epoxy resin and perfluorobutanol. The mixture was heated to 60℃ under nitrogen protection and stirred for 2.8h to obtain reaction solution B. KH-560 was added to an ethanol / water mixture and pre-hydrolyzed at 57℃ for 70min to obtain a silicon grafting solution, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 9:1 and the mass ratio of KH-560 to anhydrous ethanol was 1:2.8. This solution was added to reaction solution B to obtain a mixture, wherein the amount of KH-560 added was 13% of the total mass of alicyclic epoxy resin and perfluorobutanol. The pH was adjusted to 6.0 to obtain reaction solution C. The mixture was reacted at a constant temperature of 55℃ for 1.5h. After filtration, washing, and vacuum drying, fluorosilicone modified epoxy resin was obtained.

[0117] S2: Vinyl-terminated polydimethylsiloxane and 3-mercaptopropyltrimethoxysilane were mixed at a molar ratio of 1:1.1, and photoinitiator Irgacure 651 was added to obtain reaction solution D, wherein the mass fraction of photoinitiator in reaction solution D was 0.8 wt.%. The mixture was irradiated with ultraviolet light for 5 min to obtain a reaction mixture, wherein the irradiation intensity of ultraviolet light on reaction solution D was 25 mW / cm². 2 The modified polydimethylsiloxane was mixed with n-hexane at a volume ratio of 1:5, filtered to obtain a primary product, washed, rotary evaporated, and dried to obtain a modified polydimethylsiloxane. This modified polydimethylsiloxane was then mixed with bisphenol F epoxy resin EPON862 at a mass ratio of 1:0.9 in toluene, wherein the total mass fraction of the modified polydimethylsiloxane and bisphenol F epoxy resin in toluene was 20 wt.%. Tetraphenylphosphine bromide was added to obtain reaction solution E, wherein the amount of tetraphenylphosphine bromide added was 0.1% of the total mass of the modified polydimethylsiloxane and bisphenol F epoxy resin. The reaction was carried out at a constant temperature of 125℃ for 2.5 h, and then acid-washed with 0.1M hydrochloric acid and rotary evaporated to obtain a crude product. This crude product was dispersed in benzyl alcohol, wherein the amount of benzyl alcohol added was 38% of the mass of the crude product. Further rotary evaporation was performed to obtain a toughened prepolymer.

[0118] S3: Hyperbranched polyester Boltorn H30 and trimethyl phosphate were mixed at a molar ratio of 1:1.3, and potassium carbonate was added to obtain reaction solution F, wherein the amount of potassium carbonate added was 2.5% of the total mass of hyperbranched polyester and trimethyl phosphate. The reaction was carried out at 130°C for 8 hours under nitrogen protection to obtain the first reaction solution. The pH was adjusted to 3 with 0.2M hydrochloric acid to obtain the second reaction solution. The reaction solution was hydrolyzed and acidified at 65°C for 3 hours to obtain the third reaction solution. After cooling, the solution was poured into an ethanol / water mixture for precipitation and purification, wherein the volume ratio of ethanol to water in the ethanol / water mixture was 7:3, and the volume ratio of the third reaction solution to the ethanol / water mixture was 1:5.8. The solution was dried to obtain the phosphate polymer.

[0119] S4: Gelatin and gum arabic are mixed at a mass ratio of 1:1 and added to deionized water, where the total mass fraction of gelatin and gum arabic in the deionized water is 10 wt.%. Nano-silica is added to obtain a primary wall material solution, where the mass fraction of nano-silica in the primary wall material solution is 2 wt.%. The pH is adjusted to 4.7 to obtain a wall material solution. BF3-MEA complex is mixed with an ethanol / glycerol mixed solution at a mass ratio of 1:2.5, where the volume ratio of ethanol to glycerol in the ethanol / glycerol mixed solution is 8:2. The pH is adjusted to 3.2 to obtain a core material solution. This is then added... The reaction solution G was obtained by adding the BF3-MEA complex to the wall material solution, wherein the mass ratio of the total mass of gelatin and gum arabic was 1:2.2. The emulsion was obtained by emulsification at 50℃ for 8 min, and then cooled to 12℃ for re-coagulation for 2 h. Subsequently, isophorone diisocyanate and ethylenediamine were added to obtain reaction solution H, wherein the amount of isophorone diisocyanate added was 6% of the mass of the BF3-MEA complex, and the molar ratio of ethylenediamine to isophorone diisocyanate was 1.2:1. The crosslinking reaction was carried out at 50℃ for 3.7 h, and the microencapsulated BF3-MEA was obtained by centrifugation, washing and drying.

[0120] S5: Fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether are premixed uniformly at 45°C, and then toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain a primary product. After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic dustproofing is obtained. The mass ratio of fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, 1,4-cyclohexanediethanol diglycidyl ether, toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, EsacureTZT, microencapsulated BF3-MEA, and leveling agent FC-4430 is 32:22:20:8:9:4.2:1:4:0.4.

[0121] Comparative Example 1

[0122] This comparative example provides a cationic epoxy adhesive for electronic protection. The difference from Example 1 is that the step of reacting alicyclic epoxy resin with perfluorobutanol in S1 is omitted. Other operating steps and process parameters are exactly the same as in Example 1.

[0123] Comparative Example 2

[0124] This comparative example provides a cationic epoxy adhesive for electronic protection. The difference from Example 1 is that in S1, unmodified alicyclic epoxy resin is used directly without modification. Other operating steps and process parameters are exactly the same as in Example 1.

[0125] Comparative Example 3

[0126] This comparative example provides a cationic epoxy adhesive for electronic protection. The difference from Example 1 is that in S5, microencapsulated BF3-MEA is not added, and only UV curing is used. Other operating steps and process parameters are exactly the same as in Example 1.

[0127] The cationic epoxy adhesives for electronic conformal coating of Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests, and the specific procedures are as follows:

[0128] The viscosity of the test sample was determined according to GB / T 2794-2013;

[0129] High temperature and high humidity aging test: The sample is coated on the surface of tinplate, cured with a high-pressure mercury lamp and then naturally cured, and finally subjected to a high temperature and high humidity aging test.

[0130] The UV curing conditions are as follows: UV curing is performed using a high-pressure mercury lamp.

[0131] Natural curing conditions: Place it in a gradient constant temperature environment under light-protected conditions and let it stand (40℃ / 2h, 70-80℃ / 3h, room temperature / 24h);

[0132] The test results are shown in Table 1.

[0133] Table 1: Performance test results of cationic epoxy adhesives for electronic protection in Examples 1-4 and Comparative Examples 1-3

[0134]

[0135]

[0136] The test results of Example 1 and Comparative Example 1 show that when the step of reacting alicyclic epoxy resin with perfluorobutanol is omitted in S1, the viscosity of the adhesive increases. This is because the intermolecular interaction force between polar groups in the alicyclic epoxy resin without fluorocarbon chains is enhanced, and the molecular chain fluidity is significantly reduced, resulting in increased viscosity. At the same time, due to the lack of hydrophobic properties of fluorocarbon chains, the hygroscopicity of the material increases. Polar epoxy groups and hydroxyl groups are more likely to react with water molecules and degrade in humid and hot environments, and corrosive ions are more likely to penetrate and damage the matrix structure.

[0137] The test results from Example 1 and Comparative Example 2 show that when using unmodified alicyclic epoxy resin directly, the bulk viscosity of the unmodified alicyclic epoxy resin is low. However, due to the strong hydrogen bonds and dipole-dipole interactions between its intermolecular polar groups, it is easy to form local aggregations, resulting in a slight increase in the viscosity of the system. Since the unmodified alicyclic epoxy resin lacks the hydrophobicity of the fluorocarbon chain and the flexible structure introduced by the silicon-oxygen chain segment, the polar epoxy groups and hydroxyl groups are highly hygroscopic in humid and hot environments, leading to material deterioration. Furthermore, the unmodified alicyclic epoxy resin lacks fluorosilicone synergistic protection, and corrosive ions directly attack the interface, significantly reducing its corrosion resistance.

[0138] The test results of Example 1 and Comparative Example 3 show that when only UV curing is used without adding microencapsulated BF3-MEA, the adhesive viscosity decreases slightly. This is because omitting the microencapsulated curing agent reduces the number of solid particles in the system, resulting in a slight increase in system fluidity. However, due to insufficient UV curing depth, the material is not fully cured internally, resulting in low crosslinking density, increased hygroscopicity, and easy deterioration in humid and hot environments. Furthermore, UV curing alone leads to a large number of curing defects inside the material, which accelerates the penetration of corrosive ions at the defects, severely reducing corrosion resistance.

[0139] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a cationic epoxy adhesive for electronic protection, characterized in that, The preparation method includes: S1: Alicyclic epoxy resin ERL-4221 and perfluorobutanol are mixed at a molar ratio of 1:0.25-0.35 and reacted to obtain reaction solution B; KH-560 is added to an ethanol / water mixture for pre-hydrolysis to obtain a silicon grafting solution, which is then added to reaction solution B. The amount of KH-560 added is 10-15% of the total mass of the alicyclic epoxy resin and perfluorobutanol. The pH is adjusted to 5.5-6, and the reaction and treatment are carried out to obtain fluorosilicone modified epoxy resin. S2: Vinyl-terminated polydimethylsiloxane and 3-mercaptopropyltrimethoxysilane are mixed at a molar ratio of 1:0.9-1.1 and subjected to ultraviolet irradiation to obtain a reaction mixture. This mixture is then mixed with n-hexane and treated to obtain modified polydimethylsiloxane. This modified polydimethylsiloxane is then mixed with bisphenol F epoxy resin at a mass ratio of 1:0.7-0.9, reacted, and treated to obtain a crude product. This crude product is then dispersed in benzyl alcohol and rotary evaporated to obtain a toughened prepolymer. S3: Hyperbranched polyester and trimethyl phosphate are mixed at a molar ratio of 1:1.1-1.3 and reacted under nitrogen protection to obtain the first reaction solution. The pH is adjusted to 2.8-3 with hydrochloric acid and hydrolyzed to obtain the third reaction solution. After cooling, the solution is poured into an ethanol / water mixture to precipitate and then treated to obtain the phosphate polymer. S4: Gelatin, gum arabic, and nano-silica are added to deionized water to obtain a primary wall material solution, wherein the mass ratio of gelatin to gum arabic is 1:

1. The pH is adjusted to 4.3-4.7 to obtain a wall material solution. BF3-MEA complex is mixed with an ethanol / glycerol mixed solution, and the pH is adjusted to 2.8-3.2 to obtain a core material solution, wherein the mass ratio of BF3-MEA complex to the total mass of gelatin and gum arabic is 1:1.8-2.

2. This core material solution is mixed with the wall material solution to obtain reaction solution G. After emulsification and re-coagulation, isophorone diisocyanate and ethylenediamine are added to obtain reaction solution H. The amount of isophorone diisocyanate added is 4-6% of the mass of BF3-MEA complex, and the molar ratio of ethylenediamine to isophorone diisocyanate is 1.1-1.2:

1. The reaction is carried out and processed to obtain microencapsulated BF3-MEA. S5: After uniformly premixing fluorosilicone-modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether, toughening prepolymer, phosphate polymer, photoinitiator CPI-210S, photoinitiator Esacure TZT, microencapsulated BF3-MEA, and leveling agent FC-4430 are added sequentially to obtain the initial product. The mass ratio of TZT, microencapsulated BF3-MEA, and leveling agent FC-4430 is (28-32): (18-22): (15-20): (6-8): (7-9): (3.5-4.5): (0.5-1): (3-4): (0.3-0.4). After shear dispersion, vacuum degassing, and standing, a cationic epoxy adhesive for electronic waterproofing is obtained.

2. The method for preparing a cationic epoxy adhesive for electronic protection according to claim 1, characterized in that, In S1: The mass ratio of KH-560 to the ethanol / water mixture is 1:2-3; The volume ratio of ethanol to water in the ethanol / water mixture is 9:

1.

3. The method for preparing a cationic epoxy adhesive for electronic protection according to claim 1, characterized in that, In S2: The volume ratio of the reaction mixture to n-hexane is 1:3-5; The amount of benzyl alcohol added is 30-40% of the mass of the crude product.

4. The method for preparing a cationic epoxy adhesive for electronic protection according to claim 1, characterized in that, In S3: The volume ratio of the third reaction solution to the ethanol / water mixture is 1:5-6; The volume ratio of ethanol to water in the ethanol / water mixed solution is 7:

3.

5. The method for preparing a cationic epoxy adhesive for electronic protection according to claim 1, characterized in that, In S4: The volume ratio of ethanol to glycerol in the ethanol / glycerol mixed solution is 8:

2.

6. The method for preparing a cationic epoxy adhesive for electronic protection according to claim 1, characterized in that, In S5: The premixing temperature of the fluorosilicone modified epoxy resin, bisphenol F epoxy resin EPON862, and 1,4-cyclohexanediethanol diglycidyl ether is 40-45℃.

7. A cationic epoxy adhesive for electronic protection, prepared by the preparation method according to any one of claims 1-6.

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