UV photocuring electronic protection glue resistant to extreme high and low temperature impact and preparation method of UV photocuring electronic protection glue

Abstract

The invention relates to the technical field of protective glue, in particular to extreme high and low temperature impact resistant UV (ultraviolet) photocuring electronic protective glue which is prepared from the following raw materials in parts by weight: 30-50 parts of synergistically modified epoxy-urethane acrylate oligomer, 20-35 parts of composite active monomer, 1.5-5 parts of composite photoinitiator and 10-20 parts of core-shell structure inorganic composite filler, 0.6 to 2.2 parts of a silane coupling agent, 0.12 to 1.1 parts of an antioxidant and 0.11 to 1 part of a leveling agent; the preparation method of the synergistically modified epoxy-urethane acrylate oligomer comprises the following steps: reacting resin acid modified epoxy resin with phosphoric acid di (hydroxyethyl acrylate) ester at 80-90 DEG C, and introducing a phosphate group to obtain a phosphate modified epoxy acrylate intermediate; the protection glue unifies rigidity, flexibility and flame retardance on the molecular level through the cooperation of the hybrid oligomer and the core-shell filler, realizes high heat conductivity, strong adhesion and extremely low internal stress, and has extreme temperature impact resistance, long-term damp-heat aging resistance and high-reliability protection performance.

Description

Technical Field

[0001] This invention relates to the field of protective adhesive technology, specifically to a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks and its preparation method. Background Technology

[0002] With the continuous development of electronic information technology towards miniaturization, high density, and high power, the operating environment faced by electronic components and their packaging structures is becoming increasingly harsh. In key areas such as automotive electronics, aerospace, high-end communications, and industrial control, electronic components not only need to withstand high-intensity mechanical vibrations but are also frequently exposed to extreme temperature cycles (such as -55°C to 150°C) and high humidity environments. Against this backdrop, applying reliable protective coatings to core circuits and components to isolate them from environmental stresses such as moisture, dust, and salt spray, and to effectively manage heat distribution, has become a key technical aspect for ensuring the long-term stable operation of electronic systems. According to CN120555001A, a waterproof, high-temperature resistant, and low-temperature resistant UV-curable adhesive and its preparation method are disclosed. This technology discloses a technical solution involving: "mixing clay, maleic anhydride, and 2,6-diaminopyrazine to obtain modified clay; reacting epoxy resin and di(hydroxyethyl) phosphate to obtain modified resin; reacting octamethylcyclotetrasiloxane, mercaptopropylmethyldimethoxysilane, trifluoropropylmethyldimethoxysilane, and hexamethyldisiloxane to obtain modified organosilicon; and mixing the modified resin, modified clay, methylboric acid, and modified organosilicon to obtain a waterproof, high-temperature resistant, and low-temperature resistant UV-curable adhesive." This adhesive exhibits excellent flame retardancy, waterproofness, high-temperature resistance, and low-temperature resistance. In the above scheme, maleic anhydride and 2,6-diaminopyrazine are used to organically modify kaolin. This modification process relies on the intercalation reaction and surface polymerization of the interlayer domains of kaolin. However, kaolin is a 1:1 type non-expanding clay with strong interlayer bonding. Maleic anhydride and 2,6-diaminopyrazine are difficult to effectively insert and react uniformly, resulting in insufficient modification. The dispersion of modified clay in the resin matrix is ​​limited, and stress concentration points are easily formed due to uneven dispersion. Secondly, its flame retardant system relies on the physical mixing and synergy between phosphate-modified epoxy resin, pyrazine rings in modified clay, and methylboric acid added later. This multi-component physical blending flame retardant mechanism is unevenly distributed in the cured network and has weak interfacial bonding. Under long-term thermal stress, phase separation may occur between different components due to compatibility differences, resulting in decreased flame retardant efficiency and interfacial defects. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks and its preparation method. The protective adhesive achieves uniform rigidity, flexibility, and flame retardancy at the molecular level through the synergistic effect of hybrid oligomers and core-shell fillers, resulting in high thermal conductivity, strong adhesion, and extremely low internal stress. It also exhibits resistance to extreme temperature shocks, long-term damp heat aging, and high reliability protective performance.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks, prepared from raw materials comprising the following parts by weight: The synergistically modified epoxy-urethane acrylate oligomer consists of 30-50 parts, composite active monomers of 20-35 parts, composite photoinitiator of 1.5-5 parts, core-shell structured inorganic composite filler of 10-20 parts, silane coupling agent of 0.6-2.2 parts, antioxidant of 0.12-1.1 parts, and leveling agent of 0.11-1 parts. The preparation steps of the synergistically modified epoxy-urethane acrylate oligomer are as follows: the resin acid-modified epoxy resin is reacted with di(hydroxyethyl) phosphate at 80-90℃ to introduce phosphate groups and obtain phosphate-modified epoxy acrylate intermediate. The intermediate is then reacted with polycaprolactone diol and isophorone diisocyanate to generate a terminal isocyanate-based polyurethane prepolymer, which is then grafted under the action of a catalyst and then capped with hydroxyethyl acrylate to form a single-structure hybrid oligomer.

[0005] Preferably, the composite active monomer is a mixture of monofunctional acrylate monomers, difunctional acrylate monomers, and oxetane monomers, with a mass ratio of (1.5-2.5):(1.2-2.5):(0.6-1.2); the monofunctional acrylate monomer is selected from at least one of isobornyl acrylate and hydroxyethyl acrylate, the difunctional acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate, and the oxetane monomer is selected from 3-ethyl-3-hydroxymethyloxetane.

[0006] Preferably, the composite photoinitiator is a combination of a free radical photoinitiator and a cationic photoinitiator, with a mass ratio of (1.8:1.2) to (1:1). The free radical photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexylphenyl ketone, and the cationic photoinitiator is selected from (4-[(2-hydroxytetradecyl)oxy]phenyl)phenyliodonium hexafluorophosphate. The combination contains 3-5% of the total mass of the composite photoinitiator as a co-initiator, methyldiethanolamine.

[0007] Preferably, the core-shell structured inorganic composite filler uses nano-alumina with an average particle size of 30-60 nm as the core, and coats its surface with an organosilicon modified layer formed by co-hydrolysis of octamethylcyclotetrasiloxane and mercaptopropyltrimethoxysilane as the shell layer through in-situ hydrolysis condensation technology. The shell layer thickness is 5-15 nm. The mass ratio of nano-alumina to the coating raw material is (6:1)-(9:1).

[0008] Preferably, before being used to formulate the protective adhesive, the core-shell structured inorganic composite filler undergoes secondary surface modification using a mixed solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and vinyltriethoxysilane. The amount of the secondary modifier is 1.5-3% of the mass of the core-shell structured inorganic composite filler.

[0009] Preferably, the silane coupling agent is a mixture of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of (1:1) to (1:1.2).

[0010] Preferably, the antioxidant is a compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1.

[0011] Preferably, the leveling agent is polyether-modified polydimethylsiloxane.

[0012] This invention also discloses a method for preparing a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks, specifically including the following steps: S1. Under light-protected conditions, the formulated amount of hybrid oligomer and composite active monomer is added to the reaction vessel and stirred at 50-60℃ and 400-600rpm for 20-30 minutes to obtain the mixed premixed liquid A. S2, add the formulated amount of core-shell structured inorganic composite filler and silane coupling agent to the premix A obtained in step S1, raise the temperature to 60-70℃, disperse in a high-speed disperser at 1000-1500rpm for 50-60 minutes, and then use a three-roll mill to grind 2-3 times with roller gaps of 40-50μm, 20-30μm and 10-15μm respectively, until the slurry fineness is ≤15μm, to obtain mixture B; S3, cool the mixture B obtained in step S2 to below 40°C, add the formulated amount of composite photoinitiator, antioxidant and leveling agent, and stir in the dark at 45-55°C and 450-650 rpm for 30-60 minutes. S4. Remove air bubbles from the product obtained in step S3 under a vacuum of -0.098 to -0.1 MPa for 15-30 minutes, and then filter it using a 500-mesh filter bag to obtain UV-curable electronic protective adhesive.

[0013] This invention provides a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks and its preparation method. Compared with the prior art, it has the following advantages: 1. By integrating the rigidity of epoxy, the flexibility of polyurethane, and the flame retardancy of phosphate ester through hybrid oligomers via chemical bonds, a stable framework that resists thermal stress is constructed at the molecular level. At the same time, the core-shell filler ensures thermal conductivity with a rigid alumina core and effectively buffers thermal shock stress with a flexible silicone shell. Through structural synergy, the cured adhesive layer can maintain structural integrity without cracking or peeling under extreme temperature cycling from -55℃ to 150℃ and humid heat aging at 85℃ / 85%RH, with extremely low degradation of mechanical and electrical insulation properties.

[0014] 2. By combining composite monomers and composite initiation systems, a balance between rapid, deep curing and low internal stress is achieved. The specific ratio of monofunctional and difunctional acrylates to oxetine monomers ensures high crosslinking density and hardness while significantly reducing curing volume shrinkage and internal stress by utilizing the low shrinkage characteristics of monofunctional monomers and cationic polymerization. The synergy between free radicals and cationic photoinitiators ensures that curing is not inhibited by oxygen and has a post-curing effect, enabling thick films and complex structures to achieve complete curing consistent throughout, thereby obtaining high bonding strength and excellent adhesion.

[0015] 3. The step-by-step process of high-speed dispersion and three-roll milling ensures the ultimate dispersion and interface modification of the core-shell filler, constructing a stable thermally enhanced network; the low-temperature final mixing step effectively protects the activity of the photoinitiator, ensuring the product's storage stability and curing consistency; vacuum degassing and precision filtration completely eliminate bubbles and impurities, ensuring a dense and defect-free cured adhesive layer; further supplemented by a highly efficient antioxidant system, the product can maintain excellent electrical and mechanical properties even under long-term thermal and oxygen aging. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the synthetic pathway for the synergistically modified epoxy-urethane acrylate oligomers in this invention. Figure 2 This is a flowchart of the UV-curable electronic protective adhesive preparation process in this invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figures 1-2This invention provides a technical solution: a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks, prepared from raw materials comprising the following parts by weight: The synergistically modified epoxy-urethane acrylate oligomer consists of 30-50 parts, composite active monomers of 20-35 parts, composite photoinitiator of 1.5-5 parts, core-shell structured inorganic composite filler of 10-20 parts, silane coupling agent of 0.6-2.2 parts, antioxidant of 0.12-1.1 parts, and leveling agent of 0.11-1 parts. The preparation steps of the synergistically modified epoxy-urethane acrylate oligomer are as follows: the resin acid-modified epoxy resin is reacted with di(hydroxyethyl) phosphate at 80-90℃ to introduce phosphate groups and obtain phosphate-modified epoxy acrylate intermediate. The intermediate is then reacted with polycaprolactone diol and isophorone diisocyanate to generate a terminal isocyanate-based polyurethane prepolymer, which is then grafted under the action of a catalyst and then capped with hydroxyethyl acrylate to form a single-structure hybrid oligomer.

[0019] In this embodiment, phosphate groups are first grafted onto the resin acid-modified epoxy resin via a ring-opening reaction to form a phosphate-modified epoxy acrylate intermediate with excellent adhesion and flame retardancy. This intermediate is then grafted onto a polyurethane prepolymer with terminal isocyanate groups composed of flexible polycaprolactone diol and isophorone diisocyanate. Finally, the prepolymer is capped with hydroxyethyl acrylate. This process successfully integrates the rigidity and high adhesion of the epoxy segments, the flexibility and impact resistance of the polyurethane segments, and the flame retardancy and metal adhesion enhanced by the phosphate structure into a single hybrid oligomer structure at the molecular level through stable chemical bonds. Then, using 30-50 parts of this hybrid oligomer as a backbone, 20-35 parts of a composite active monomer (monofunctional, difunctional, and cationic) are added. The synergistic effect of ionic monomer blends ensures a precise balance between low shrinkage, high crosslinking density, and low internal stress in the cured network; 1.5-5 parts of composite photoinitiator (free radical / cationic blend) guarantee curing efficiency and depth; 10-20 parts of specially formulated core-shell inorganic composite filler (alumina core / organosilicon shell) impart high thermal conductivity to the system while effectively buffering thermal stress through a flexible shell; further supplemented with specific amounts of silane coupling agent, antioxidant, and leveling agent, providing support in terms of enhancing interfacial bonding, ensuring long-term thermal stability, and optimizing film quality; through the multifunctional synergy of each component and precise dosage control, comprehensive performance including high bonding strength, high hardness, high thermal conductivity, high flame retardancy, and excellent weather resistance is achieved.

[0020] Specifically, the composite active monomer is a mixture of monofunctional acrylate monomers, difunctional acrylate monomers, and oxetane monomers, with a mass ratio of (1.5-2.5):(1.2-2.5):(0.6-1.2); the monofunctional acrylate monomer is selected from at least one of isobornyl acrylate and hydroxyethyl acrylate, the difunctional acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate, and the oxetane monomer is selected from 3-ethyl-3-hydroxymethyloxetane.

[0021] In this embodiment, monofunctional acrylate monomers (such as isobornyl acrylate / hydroxyethyl acrylate) effectively dilute the system and isolate crosslinking points through their long-chain or side-group structures, significantly reducing the volume shrinkage and internal stress during curing, thereby enhancing the adhesion of the adhesive layer to the substrate and its crack resistance. Difunctional acrylate monomers (such as 1,6-hexanediol diacrylate / tripropylene glycol diacrylate) serve as the crosslinking backbone, rapidly constructing a three-dimensional network structure to ensure the curing rate and the crosslinking density of the final adhesive layer, endowing the material with the necessary mechanical strength, hardness, and heat resistance. Meanwhile, oxetane monomers (such as 3-ethyl-3-hydroxymethyloxetane) exhibit extremely low shrinkage during curing through their unique cationic polymerization mechanism and can undergo ring-opening reactions with epoxy or hydroxyl groups in the system, further strengthening interfacial bonding, increasing network density, and producing a synergistic effect with free radical polymerization, overcoming the influence of oxygen inhibition and ensuring deep curing effect. The synergistic effect of these three monomers in this specific ratio achieves a balance between low stress, high crosslinking density, and rapid deep curing, which is the key to obtaining excellent comprehensive performance of the protective adhesive.

[0022] Specifically, the composite photoinitiator is a combination of a free radical photoinitiator and a cationic photoinitiator, with a mass ratio of (1.8:1.2) to (1:1). The free radical photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexylphenyl ketone, and the cationic photoinitiator is selected from (4-[(2-hydroxytetradecyl)oxy]phenyl)phenyliodonium hexafluorophosphate. The combination also contains methyl diethanolamine as a co-initiator, accounting for 3-5% of the total mass of the composite photoinitiator.

[0023] In this embodiment, the free radical photoinitiator (such as 2-hydroxy-2-methyl-1-phenyl-1-propanone or 1-hydroxycyclohexylphenyl ketone) rapidly decomposes under UV irradiation to generate free radicals, which are mainly responsible for initiating the rapid polymerization of acrylate double bonds, ensuring that the system obtains excellent surface drying speed and initial mechanical strength; while the cationic photoinitiator ((4-[(2-hydroxytetradecyl)oxy]phenyl)phenyliodonium hexafluorophosphate) generates a superacid after absorbing light energy, which can simultaneously initiate the ring-opening polymerization of epoxy groups and the cationic polymerization of oxetane monomers. This polymerization process is not inhibited by oxygen and has small volume shrinkage. It also has a "post-curing" effect, which can continuously deepen the curing degree and significantly improve the adhesion and heat resistance of the adhesive layer to the substrate; at a mass ratio of (1.8:1.2)-(1:1), the free radical polymerization and cationic polymerization rates are well matched, avoiding the internal stress problem caused by excessive curing shrinkage difference; the co-initiator methyl diethanolamine, which accounts for 3-5% of the total mass of the composite photoinitiator, on the one hand, acts as a hydrogen donor and a component of the hydrogen abstraction mechanism, effectively enhancing the initiation efficiency and overcoming surface oxygen inhibition; on the other hand, its tertiary amine structure can also neutralize the acidic components in the system and improve storage stability.

[0024] Specifically, the core-shell structured inorganic composite filler uses nano-alumina with an average particle size of 30-60nm as the core, and coats its surface with an organosilicon modified layer formed by the co-hydrolysis of octamethylcyclotetrasiloxane and mercaptopropyltrimethoxysilane as the shell layer through in-situ hydrolysis condensation technology. The shell layer has a thickness of 5-15nm. The mass ratio of nano-alumina to the coating raw material is (6:1)-(9:1).

[0025] In this embodiment, using nano-alumina with an average particle size of 30-60 nm as the core, the high thermal conductivity (theoretical thermal conductivity of approximately 30 W / (m·K)) is utilized to construct an efficient heat conduction path within the polymer matrix, thereby significantly improving the overall thermal conductivity of the colloid. An organosilicon polymer shell (5-15 nm thick) formed by the co-hydrolysis of octamethylcyclotetrasiloxane (D4H) and mercaptopropyltrimethoxysilane is coated onto the alumina surface using in-situ hydrolysis condensation technology. This flexible shell acts as a crucial stress buffer interface, with a modulus far lower than that of the alumina core and resin matrix. It effectively absorbs and disperses internal stress caused by the mismatch in thermal expansion coefficients during high and low temperature impacts, inhibiting the initiation and propagation of microcracks and greatly enhancing the impact toughness of the colloid. Simultaneously, the control of nano-alumina... The mass ratio of alumina to the coating material is (6:1)-(9:1), which allows for precise control of the shell thickness within this optimal range. This ensures that sufficient stress buffering is provided without excessively increasing interfacial thermal resistance, thus achieving an optimal balance between enhanced thermal conductivity and mechanical compatibility. The mercapto groups (-SH) introduced by mercaptopropylsilane can also act as hydrogen donors, assisting in cross-linking with double bonds in the system during photocuring, further enhancing the interfacial chemical bonding between the filler and the resin matrix and preventing interfacial peeling. The composite structure of "rigid core and flexible shell" fundamentally unifies the contradictory requirements of high thermal conductivity and high toughness, which is the core of the protective adhesive's excellent resistance to extreme temperature cycling.

[0026] Specifically, before being used to formulate protective adhesives, the core-shell structure inorganic composite filler undergoes secondary surface modification using a mixed solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and vinyltriethoxysilane. The amount of the secondary modifier is 1.5-3% of the mass of the core-shell structure inorganic composite filler.

[0027] In this embodiment, the silanol groups formed by the hydrolysis of silane undergo a condensation reaction with the silanol groups on the surface shell of the filler, thereby firmly introducing two organic functional groups with different reactivity onto the filler surface. Specifically, the epoxy groups provided by KH560 can undergo ring-opening reactions with the hydroxyl and carboxyl groups of hybrid oligomers in the resin matrix, forming strong chemical bonds. This greatly enhances the interfacial compatibility and adhesion between the filler and the polar resin matrix, effectively preventing peeling under stress due to weak interfaces. Meanwhile, the vinyl groups provided by vinyltriethoxysilane can directly participate in UV curing. During the process, it undergoes a copolymerization reaction with the acrylate double bonds in the system, thereby building a robust "molecular bridge" between the inorganic filler and the organic polymer network, transforming the filler from a physical filling point into a chemical node in the cross-linked network. The amount of secondary modifier is precisely controlled at 1.5-3% of the mass of the core-shell filler to ensure the formation of a dense and monolayer modified layer on the filler surface. Too little will result in incomplete coverage and poor interface improvement, while too much will cause silane molecules to agglomerate, introducing defects at the interface. This improves the mechanical strength, thermal conductivity stability, and long-term aging resistance of the composite material.

[0028] Specifically, the silane coupling agent is a mixture of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of (1:1) to (1:1.2).

[0029] In this embodiment, the terminal amino group (-NH2) of γ-aminopropyltriethoxysilane possesses strong polarity and reactivity. It can not only form strong hydrogen bonds and chemical bonds with the surface of inorganic substrates (such as glass fibers and silica in FR-4 boards), but also react chemically with the epoxy groups of the epoxy acrylate segments in the resin matrix and the isocyanate derivative groups in the polyurethane segments. This acts as a "bridge," greatly enhancing the adhesion of the protective adhesive to various substrates, particularly improving initial bond strength and resistance to damp heat aging. Meanwhile, after anchoring at the inorganic interface, the vinyl groups of vinyltrimethoxysilane can... It directly participates in the free radical polymerization reaction of UV curing, copolymerizing with acrylate monomers and oligomers in the system, thereby achieving covalent bonding from inorganic to organic phases at the interface, significantly enhancing the chemical stability and mechanical strength of the interface layer; the two work synergistically in this specific ratio, ensuring that the interface layer can achieve broad chemical anchoring through amino groups and efficient integration with the curing network through vinyl groups, avoiding the interface weakness problem caused by the functional limitations of single silanes. Ultimately, the cured adhesive layer can withstand the huge shear stress generated by extreme high and low temperature impacts, which is a key guarantee for achieving high reliability protection.

[0030] Specifically, the antioxidant is a compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:1.

[0031] In this embodiment, hindered phenolic antioxidant 1010 serves as the primary antioxidant. Its steric hindrance allows it to efficiently capture alkyl and peroxide radicals generated during long-term thermo-oxidative aging of the polymer, interrupting the chain reaction and preventing polymer chain breakage and cross-linking. This effectively inhibits the embrittlement and mechanical property degradation of the material at high temperatures. Phosphite antioxidant 168, as an auxiliary antioxidant, primarily functions to decompose hydroperoxides generated during polymer processing and use, converting them into stable non-radical products. This eliminates the key initiator causing material aging at its source, preventing the initiation of autocatalytic oxidation. When the two are compounded in a 1:1 ratio, 1010 and 168 complement and synergize functionally, constructing a comprehensive, multi-layered protective network encompassing free radical capture and hydroperoxide decomposition. This synergistic effect significantly enhances the protective adhesive's resistance to thermo-oxidative aging during high-temperature curing, long-term operation at high ambient temperatures, and harsh humid and hot conditions, ensuring the long-term stability of its electrical, mechanical, and appearance properties, and greatly extending the service life of electronic components.

[0032] Specifically, the leveling agent is polyether-modified polydimethylsiloxane.

[0033] In this embodiment, the polydimethylsiloxane backbone has extremely low surface tension, enabling it to rapidly migrate to the surface of the liquid colloid and form a uniform surface layer. This effectively reduces the surface tension of the entire system, allowing the adhesive to spread and level quickly after coating, eliminating surface defects such as Bénard eddies and orange peel caused by uneven surface tension. Simultaneously, its grafted polyether segments exhibit good compatibility with the acrylate resin system. This design avoids the side effects of poor compatibility in traditional polydimethylsiloxanes, such as pinholes and foaming, ensuring uniformity and stability in the leveling process. Through this efficient surface state control, the leveling agent helps form a smooth, flat, and uniformly thick cured film. This not only improves the product's appearance quality but, more importantly, a defect-free, uniform surface and cross-sectional structure effectively avoids localized stress concentration, significantly enhancing the integrity and reliability of the adhesive layer under extreme high and low temperature shocks. It is a key additive ensuring consistent final protective performance.

[0034] This invention also discloses a method for preparing a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks, specifically including the following steps: S1. Under light-protected conditions, the formulated amount of hybrid oligomer and composite active monomer is added to the reaction vessel and stirred at 50-60℃ and 400-600rpm for 20-30 minutes to obtain the mixed premixed liquid A. S2, add the formulated amount of core-shell structured inorganic composite filler and silane coupling agent to the premix A obtained in step S1, raise the temperature to 60-70℃, disperse in a high-speed disperser at 1000-1500rpm for 50-60 minutes, and then use a three-roll mill to grind 2-3 times with roller gaps of 40-50μm, 20-30μm and 10-15μm respectively, until the slurry fineness is ≤15μm, to obtain mixture B; S3, cool the mixture B obtained in step S2 to below 40°C, add the formulated amount of composite photoinitiator, antioxidant and leveling agent, and stir in the dark at 45-55°C and 450-650 rpm for 30-60 minutes. S4. Remove air bubbles from the product obtained in step S3 under a vacuum of -0.098 to -0.1 MPa for 15-30 minutes, and then filter it using a 500-mesh filter bag to obtain UV-curable electronic protective adhesive.

[0035] In this embodiment, premixing is performed in step S1 at 50-60℃ and medium speed. This temperature and shear condition effectively reduces the viscosity of hybrid oligomers and some monomers to achieve uniform blending, while avoiding premature side reactions of active components due to excessively high temperatures, thus establishing a uniform and stable liquid phase foundation for the system. Step S2 is crucial to ensuring that the core-shell inorganic composite filler achieves the expected reinforcing effect. First, dispersion is performed at 60-70℃ and 1000-1500 rpm, using heat energy to reduce resin viscosity and high-intensity shear force to initially break up filler aggregates. Then, a three-roll mill is used for fine grinding with stepped gaps (40-50μm→20-30μm→10-15μm). This process thoroughly destroys the remaining filler agglomerates through huge shear and friction forces, and silane coupling agents are used at this time to achieve further coating and reaction on the filler surface, ultimately strictly controlling the fineness of the slurry. The filler's specific surface area and dispersion are maximized to achieve a ≤15μm particle size, thus creating a highly efficient and stable thermally conductive and reinforcing network while avoiding stress concentration points caused by agglomerates. Step S3 involves cooling mixture B to below 40°C before introducing heat-sensitive components such as photoinitiators. This step is crucial as it effectively prevents the photoinitiator from undergoing thermal pre-decomposition during mixing, ensuring product stability during storage and abundant and consistent curing activity under UV irradiation. The final step S4 involves high-vacuum degassing to completely eliminate air trapped during high-speed dispersion and grinding, preventing microbubbles in the cured adhesive layer from becoming electrical insulation weaknesses or stress cracking sources. Precision filtration through a 500-mesh filter bag effectively traps any undispersed impurities or gel particles that may have been generated in the aforementioned processes, ensuring the final product has extremely high purity and consistency, meeting the stringent reliability requirements of high-end electronic protection.

[0036] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks, characterized in that, It is prepared from raw materials comprising the following parts by weight: The synergistically modified epoxy-urethane acrylate oligomer consists of 30-50 parts, composite active monomers of 20-35 parts, composite photoinitiator of 1.5-5 parts, core-shell structured inorganic composite filler of 10-20 parts, silane coupling agent of 0.6-2.2 parts, antioxidant of 0.12-1.1 parts, and leveling agent of 0.11-1 parts. The preparation steps of the synergistically modified epoxy-urethane acrylate oligomer are as follows: the resin acid-modified epoxy resin is reacted with di(hydroxyethyl) phosphate at 80-90℃ to introduce phosphate groups and obtain phosphate-modified epoxy acrylate intermediate. The intermediate is then reacted with polycaprolactone diol and isophorone diisocyanate to generate a terminal isocyanate-based polyurethane prepolymer, which is then grafted under the action of a catalyst and then capped with hydroxyethyl acrylate to form a single-structure hybrid oligomer.

2. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: The composite active monomer is a mixture of monofunctional acrylate monomers, difunctional acrylate monomers, and oxetane monomers in a mass ratio of (1.5-2.5):(1.2-2.5):(0.6-1.2); the monofunctional acrylate monomer is selected from at least one of isobornyl acrylate and hydroxyethyl acrylate, the difunctional acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate and tripropylene glycol diacrylate, and the oxetane monomer is selected from 3-ethyl-3-hydroxymethyloxetane.

3. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: The composite photoinitiator is a combination of a free radical photoinitiator and a cationic photoinitiator in a mass ratio of (1.8:1.2) to (1:1). The free radical photoinitiator is selected from at least one of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexylphenyl ketone, and the cationic photoinitiator is selected from (4-[(2-hydroxytetradecyl)oxy]phenyl)phenyliodonium hexafluorophosphate. The combination contains methyl diethanolamine as a co-initiator, accounting for 3-5% of the total mass of the composite photoinitiator.

4. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: The core-shell structured inorganic composite filler uses nano-alumina with an average particle size of 30-60 nm as the core, and coats its surface with an organosilicon modified layer formed by the co-hydrolysis of octamethylcyclotetrasiloxane and mercaptopropyltrimethoxysilane as the shell layer through in-situ hydrolysis condensation technology. The shell layer has a thickness of 5-15 nm. The mass ratio of nano-alumina to the coating material is (6:1)-(9:1).

5. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: Before being used to formulate protective adhesives, the core-shell structured inorganic composite filler undergoes secondary surface modification using a mixed solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and vinyltriethoxysilane. The amount of the secondary modifier is 1.5-3% of the mass of the core-shell structured inorganic composite filler.

6. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: The silane coupling agent is a mixture of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane in a mass ratio of (1:1) to (1:1.2).

7. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: The antioxidant is a compound of hindered phenolic antioxidant 1010 and phosphite antioxidant 168 in a mass ratio of 1:

1.

8. The UV-curable electronic protective adhesive resistant to extreme high and low temperature shock according to claim 1, characterized in that: The leveling agent is polyether-modified polydimethylsiloxane.

9. A method for preparing a UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks, characterized in that: The UV-curable electronic protective adhesive resistant to extreme high and low temperature shocks as described in any one of claims 1-8 specifically includes the following steps: S1. Under light-protected conditions, the formulated amount of hybrid oligomer and composite active monomer is added to the reaction vessel and stirred at 50-60℃ and 400-600rpm for 20-30 minutes to obtain the mixed premixed liquid A. S2, add the formulated amount of core-shell structured inorganic composite filler and silane coupling agent to the premix A obtained in step S1, raise the temperature to 60-70℃, disperse in a high-speed disperser at 1000-1500rpm for 50-60 minutes, and then use a three-roll mill to grind 2-3 times with roller gaps of 40-50μm, 20-30μm and 10-15μm respectively, until the slurry fineness is ≤15μm, to obtain mixture B; S3, cool the mixture B obtained in step S2 to below 40°C, add the formulated amount of composite photoinitiator, antioxidant and leveling agent, and stir in the dark at 45-55°C and 450-650 rpm for 30-60 minutes. S4. Remove air bubbles from the product obtained in step S3 under a vacuum of -0.098 to -0.1 MPa for 15-30 minutes, and then filter it using a 500-mesh filter bag to obtain UV-curable electronic protective adhesive.

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