Preparation and application of a heat-conducting and electricity-conducting acrylate pressure-sensitive adhesive

Abstract

The application discloses a preparation and application of a heat-conducting and electricity-conducting acrylic ester pressure-sensitive adhesive. The preparation method comprises the following steps: dispersing a reactive emulsifier and acrylic ester mixed monomers in water, adding alkyl halide, a copper-based catalyst and a nitrogen-containing ligand after emulsification, adding a water-soluble reducing agent under an inert atmosphere, and obtaining an acrylic ester polymer emulsion after heating reaction; performing silanization modification on boron nitride nanosheets, performing amidation reaction with carboxylated silver-coated copper nanowires to obtain fillers with a core-shell structure; dispersing the modified boron nitride nanosheets in the acrylic ester polymer emulsion, adding fillers and temperature-sensitive monomers, uniformly mixing, adding a photoinitiator and a latent curing agent, and uniformly mixing to obtain the heat-conducting and electricity-conducting acrylic ester pressure-sensitive adhesive. The polymer emulsion matrix prepared by the application can ensure sufficient dispersion of multi-dimensional heterogeneous fillers, improve the uniformity of the electric conductivity and the heat conductivity of the pressure-sensitive adhesive after film formation, and successfully realizes reliable and stable temperature-sensitive response in the solid pressure-sensitive adhesive.

Description

Technical Field

[0001] This invention relates to an acrylic ester pressure-sensitive adhesive, and more particularly to the preparation and application of a thermally conductive and electrically conductive acrylic ester pressure-sensitive adhesive. Background Technology

[0002] With the rapid development of power battery technology, extremely high requirements have been placed on interfacial bonding materials. Currently, most commercially available pressure-sensitive adhesives are single-function products, which are difficult to meet the multiple demands of intelligent response, efficient thermal management, and stable electrical transmission. Although some studies have attempted to improve these products by adding fillers, problems such as uneven filler dispersion, difficulty in performance synergy, and unreliable preparation methods often arise. In particular, applying reactive controlled polymerization technologies (such as RAFT and ATRP) to emulsion systems to achieve a structurally regular polymer matrix still presents technical challenges.

[0003] In the manufacturing, cutting, handling, and assembly of flexible OLED displays, the screen surface is highly susceptible to scratches, dust contamination, and chemical corrosion, necessitating the use of high-performance temporary protective films. Currently, most commercially available temporary protective films are made using traditional acrylic pressure-sensitive adhesives. While these adhesives offer decent initial tack, their peel strength is often fixed. If the peel strength is too high, the immense adhesive force during film peeling may exceed the flexible substrate's tolerance limit, causing the screen's thin film layer to be pulled up (interlayer peeling) or residual stress to cause minute deformations, resulting in irreversible damage to delicate circuitry. Conversely, if the peel strength is too low, it cannot provide sufficient protection during the manufacturing process, leading to premature warping and detachment of the protective film. Therefore, protective films made with pressure-sensitive adhesives need to possess the ability to intelligently respond to changes in peel strength.

[0004] Chinese patent CN115975554A discloses a pressure-sensitive adhesive, which, despite attempts to add fillers, fails to achieve temperature sensitivity and exhibits limited performance. Furthermore, while many studies have focused on the temperature sensitivity of PNIPAM hydrogels, their application to dry solid pressure-sensitive adhesive interfaces still faces technical bottlenecks, such as uneven dispersion and unclear mechanisms. Currently, the industry's pursuit of multifunctional pressure-sensitive adhesives mainly faces two technical paths and their inherent drawbacks: one is the simple physical blending of various functional fillers (such as thermally conductive and electrically conductive fillers) into traditional adhesive matrices, which easily leads to uneven filler dispersion, poor interfacial compatibility, unstable performance, and easy migration; the other is the use of conventional emulsion polymerization to prepare the matrix, whose polymer molecular chain structure has poor regularity, making it difficult to form effective steric hindrance and interactions for high-performance fillers, also leading to filler agglomeration and performance degradation. Therefore, developing a preparation method that can solve the dispersion and synergy problems from the source of matrix structure design and filler interface engineering is key to achieving high-performance integrated pressure-sensitive adhesives.

[0005] In summary, developing a reliable and high-performance multifunctional integrated smart pressure-sensitive adhesive has become an urgent technical challenge in this field. Summary of the Invention

[0006] Objective of this invention: The objective of this invention is to provide a method for preparing a thermally conductive and electrically conductive acrylate pressure-sensitive adhesive, solving the problem of how to prepare an acrylate pressure-sensitive adhesive that combines intelligent responsiveness, high thermal conductivity, and high electrical conductivity. Another objective of this invention is to propose the application of this thermally conductive and electrically conductive acrylate pressure-sensitive adhesive in the preparation of temporary protective films for flexible OLED screens or thermally conductive and electrically conductive bonding interfaces for power battery modules, thus solving the problem of how to prepare such interfaces.

[0007] Technical solution: The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive of the present invention includes the following steps: (1) Disperse the reactive emulsifier and the acrylate monomer mixture in water, emulsify to obtain the first emulsion, add alkyl halide, copper-based catalyst and nitrogen-containing ligand to the first emulsion, add water-soluble reducing agent under an inert atmosphere, heat to react and obtain acrylate polymer emulsion; (2) Boron nitride nanosheets were modified by silanization to obtain f-BNNS. f-BNNS was then subjected to amidation reaction with carboxylated silver-coated copper nanowires to obtain Ag@Cu NWs@f-BNNS with a core-shell structure. (3) Disperse f-BNNS in an acrylate polymer emulsion, then add Ag@Cu NWs@f-BNNS and thermo-responsive monomers, disperse and mix well, then add photoinitiator and latent curing agent and mix well to obtain thermally conductive and electrically conductive acrylate pressure-sensitive adhesive.

[0008] The temperature-sensitivity mechanism of this invention is based on multiple synergistic effects, including: Microenvironment hydration: Although the acrylate matrix is ​​hydrophobic, the introduced hydrophilic monomers (such as hydroxyethyl acrylate and acrylic acid) can adsorb trace amounts of water from the environment, forming a local hydration microenvironment within the polymer network, providing the solvation conditions required for conformational changes of the N-isopropylacrylamide segments. Network internal stress regulation: When the temperature changes, the N-isopropylacrylamide segments undergo hydrophilic-hydrophobic transition (LCST ~32°C), causing the segments to collapse or extend, generating internal stress in the crosslinked network, which is macroscopically manifested as a reversible change in peeling force; Synergistic effect of filler thermal conductivity: The highly thermally conductive filler (Ag@Cu NWs@f-BNNS) uniformly dispersed in the acrylate polymer emulsion ensures rapid and uniform heat transfer, amplifying the consistency and reliability of the temperature-sensitive response.

[0009] Preferably, in step (1), the reactive emulsifier is sodium allyloxyhydroxypropyl sulfonate; the alkyl halide is α-bromophenylethane; the copper-based catalyst is copper halide; the nitrogen-containing ligand is 4,4'-dinonyl-2,2'-bipyridine; and the water-soluble reducing agent is ascorbic acid.

[0010] This invention employs the AGET ATRP emulsion polymerization method to prepare acrylate polymer emulsions. This technology utilizes a water-soluble reducing agent (such as ascorbic acid) to regenerate the active species (Cu) of the catalyst in the reaction process. + The method ( / L) successfully solves the problem that traditional ATRP technology is difficult to implement in aqueous systems, and can obtain polymer emulsions with narrow molecular weight distribution (PDI<1.3), well-defined end groups and high reactivity, providing an ideal matrix for subsequent functional integration.

[0011] Preferably, in step (1), the acrylate mixed monomers include isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid, and the heating reaction conditions are 60-70°C for 6-12 hours.

[0012] In some embodiments, copper halides include at least one of copper bromide, copper chloride, and cuprous iodide.

[0013] Preferably, in step (2), the silanization modification method is as follows: Boron nitride nanosheets were dispersed in an aqueous alcohol solution, a silane coupling agent was added, and the mixture was heated under reflux. The reaction product was centrifuged to collect the precipitate, which was then washed and dried to obtain f-BNNS. The method for carboxylation treatment is as follows: Silver-coated copper nanowires were dispersed in water, and then excess mercaptosuccinic acid was added. The mixture was stirred at room temperature, and the reaction product was centrifuged to collect the precipitate. The precipitate was washed to obtain c-Ag@Cu NWs. The amidation reaction method is as follows: f-BNNS and c-Ag@Cu NWs were dispersed in a buffer solution, and carbodiimide and N-hydroxysuccinimide were added. After reacting at room temperature, the precipitate was collected by centrifugation. The precipitate was washed and dried to obtain Ag@Cu NWs@f-BNNS.

[0014] This invention, in preparing Ag@Cu NWs@f-BNNS packings, abandons the difficult-to-implement "hydrothermal in-situ growth" method and innovatively adopts a "surface modification-self-assembly" technology to construct Ag@Cu NWs@f-BNNS core-shell heterogeneous packings. First, BNNS is silanized to introduce amino groups (-NH2), and Ag@Cu NWs is carboxylated to introduce carboxyl groups (-COOH). Then, covalent grafting of the two is achieved through an amidation reaction. The process is reliable and has good reproducibility.

[0015] Furthermore, the boron nitride nanosheets have an average particle size of 400-600 nm, the aqueous solution of alcohol is a methanol or ethanol aqueous solution with a concentration of 50-75%, and the silane coupling agent is 3-aminopropyltriethoxysilane. The ratio of boron nitride nanosheets to an aqueous solution of alcohol is 1-5 g: 100-1000 mL; the heating and reflux conditions are reflux reaction at 60-90℃ for 3-7 h.

[0016] Preferably, in step (3), the thermo-responsive monomer is N-isopropylacrylamide, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone or its derivative, and the latent curing agent is a blocked isocyanate.

[0017] This invention employs a stepwise mixing process, preferentially dispersing f-BNNS in an acrylate polymer emulsion to construct a basic thermally conductive network, then adding Ag@Cu NWs@f-BNNS composite filler and a smart temperature-sensitive monomer, and finally adding a time-curing system consisting of a photoinitiator and a latent thermosetting agent. This ensures the uniform dispersion and orderly integration of each functional component. Through photo-thermal time-triggered dual curing, the final product performance is achieved.

[0018] Preferably, in step (3), the mass ratio of the acrylate polymer emulsion, the thermo-responsive monomer, Ag@Cu NWs@f-BNNS, the photoinitiator and the latent curing agent is 100:3-10:10-30:0.5-1.5:0.5-3.5.

[0019] The second aspect of this invention discloses the application of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive prepared by the above-mentioned preparation method in the preparation of temporary protective films for flexible OLED screens or thermally conductive and electrically conductive bonding interfaces for power battery modules.

[0020] The method for preparing a temporary protective film for a flexible OLED screen or a thermally conductive and conductive bonding interface for a power battery module using the above-mentioned thermally conductive and conductive acrylate pressure-sensitive adhesive includes the following steps: The thermally conductive and conductive acrylate pressure-sensitive adhesive is applied to the base film or bonding interface. The applied thermally conductive and conductive acrylate pressure-sensitive adhesive is first cured by ultraviolet light and then cured by heating.

[0021] Preferably, the energy intensity of the ultraviolet light is 300-500 mJ / cm². 2 The heating and curing method involves heat treatment at 60-80℃ for 10-20 minutes to complete the curing process.

[0022] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: This invention uses the AGET ATRP method to prepare a structurally regular acrylate polymer emulsion as a matrix. This polymer emulsion matrix can ensure the full dispersion of multidimensional heterogeneous fillers, improve the electrical and thermal uniformity of the pressure-sensitive adhesive film, and successfully achieve a reliable and stable temperature-sensitive response in solid pressure-sensitive adhesives.

[0023] The pressure-sensitive adhesive prepared by this invention successfully integrates multiple functions such as intelligent temperature-sensitive response, high thermal conductivity, and high electrical conductivity, with performance indicators significantly superior to traditional products. The pressure-sensitive adhesive prepared by this invention is particularly suitable for the fields of electronic and new energy batteries, providing a novel solution to the interface material challenges. Detailed Implementation

[0024] The technical solution of the present invention will be further described below.

[0025] Example 1: A method for preparing a thermally conductive and electrically conductive acrylate pressure-sensitive adhesive is as follows: (1) By weight, 70 parts of isooctyl acrylate, 20 parts of methyl methacrylate, 5 parts of hydroxyethyl acrylate and 3 parts of acrylic acid are mixed to obtain a mixed monomer of acrylates; Two parts of sodium allyl hydroxypropyl sulfonate (HAPS) and 98 parts of acrylate monomers were dispersed in 100 parts of water and pre-emulsified at high speed of 8000 rpm for 30 min to obtain the first emulsion. The first emulsion was transferred to a reactor, and 0.1 parts of α-bromophenyl ethane (EBiB), 0.05 parts of CuBr2 and 0.15 parts of 4,4'-dinonyl-2,2'-bipyridine (dNbpy) were added to the first emulsion. Nitrogen gas was purged for 30 min to remove oxygen, and the temperature was raised to 60°C under nitrogen atmosphere. Then, 0.2 parts of ascorbic acid were added, and the reaction was continued for 10 h to obtain an acrylate polymer emulsion with a solid content of about 38% and a PDI of 1.18. (2) 1g of boron nitride nanosheets with an average particle size of 500 nm were dispersed in 200mL of 65% ethanol aqueous solution, 3g of 3-aminopropyltriethoxysilane was added, and the mixture was heated to 75℃ and refluxed for 5h. The reaction product was centrifuged to collect the precipitate, and the precipitate was washed with water and dried to obtain f-BNNS. 1 g of silver-coated copper nanowires (Ag@CuNWs, diameter 50 nm, length 10-20 μm) were dispersed in 100 mL of water, and then excess mercaptosuccinic acid was added. The mixture was stirred at room temperature for 12 h. The reaction product was centrifuged to collect the precipitate, and the precipitate was washed with water to obtain c-Ag@Cu NWs. By weight, 5 parts of f-BNNS and 10 parts of c-Ag@Cu NWs were dispersed in 100 mL of MES buffer at pH 6. 0.5 parts of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and 0.2 parts of N-hydroxysuccinimide (NHS) were added. After amidation reaction at room temperature for 24 h, the precipitate was collected by centrifugation. The precipitate was washed with water and dried to obtain Ag@Cu NWs@f-BNNS.

[0026] (3) By weight, add 5 parts of f-BNNS to 100 parts of acrylate polymer emulsion, stir and shear disperse at 10,000 rpm for 40 min, then add 15 parts of Ag@Cu NWs@f-BNNS and 5 parts of N-isopropylacrylamide, stir and disperse at 10,000 rpm for 30 min, then add 1 part of 2-hydroxy-2-methyl-1-phenyl-1-propanone or its derivative and 2 parts of blocked isocyanate (e.g., Covestro's Bayhydur BL 5335), stir and mix at 300 rpm to obtain thermally conductive and conductive acrylate pressure-sensitive adhesive.

[0027] Example 2: A method for preparing a thermally conductive and electrically conductive acrylate pressure-sensitive adhesive is as follows: (1) By weight, 65 parts of isooctyl acrylate, 25 parts of methyl methacrylate, 5 parts of hydroxyethyl acrylate and 5 parts of acrylic acid are mixed to obtain a mixed monomer of acrylates; Three parts of sodium allyl hydroxypropyl sulfonate (HAPS) and 100 parts of acrylate monomers were dispersed in 100 parts of water and pre-emulsified at high speed of 9000 rpm for 30 min to obtain the first emulsion. The first emulsion was transferred to a reactor, and 0.2 parts of α-bromophenyl ethane (EBiB), 0.07 parts of CuBr2 and 0.13 parts of 4,4'-dinonyl-2,2'-bipyridine (dNbpy) were added to the first emulsion. Nitrogen gas was purged for 30 min to remove oxygen, and the temperature was raised to 70°C under nitrogen atmosphere. Then, 0.5 parts of ascorbic acid were added and reacted for 6 h to obtain an acrylate polymer emulsion with a solid content of about 41% and a PDI of 1.23. (2) 5g of boron nitride nanosheets with an average particle size of 600 nm were dispersed in 1000mL of 75% ethanol aqueous solution, 6g of 3-aminopropyltriethoxysilane was added, and the mixture was heated to 90℃ and refluxed for 3h. The reaction product was centrifuged to collect the precipitate, and the precipitate was washed with water and dried to obtain f-BNNS. 3g of silver-coated copper nanowires (Ag@CuNWs, diameter 50 nm, length 10-20 μm) were dispersed in 100 mL of water, and then excess mercaptosuccinic acid was added. The mixture was stirred at room temperature for 10 h. The reaction product was centrifuged to collect the precipitate, and the precipitate was washed with water to obtain c-Ag@Cu NWs. By weight, 5 parts f-BNNS and 10 parts c-Ag@Cu NWs were dispersed in 80 mL of MES buffer at pH 6, 0.5 parts EDC and 0.2 parts NHS were added, and the amidation reaction was carried out at room temperature for 24 h. After centrifugation, the precipitate was collected, washed with water and dried to obtain Ag@Cu NWs@f-BNNS.

[0028] (3) By weight, add 5 parts of f-BNNS to 100 parts of acrylate polymer emulsion, stir and shear disperse at 10000 rpm for 40 min, then add 30 parts of Ag@Cu NWs@f-BNNS and 10 parts of N-isopropylacrylamide, stir and disperse at 10000 rpm for 30 min, then add 1.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone or its derivative and 3.5 parts of blocked isocyanate, stir and mix at 400 rpm to obtain thermally conductive and conductive acrylate pressure-sensitive adhesive.

[0029] Example 3: A method for preparing a thermally conductive and electrically conductive acrylate pressure-sensitive adhesive is as follows: (1) By weight, 75 parts of isooctyl acrylate, 15 parts of methyl methacrylate, 8 parts of hydroxyethyl acrylate and 2 parts of acrylic acid are mixed to obtain a mixed monomer of acrylates; One part of sodium allyl hydroxypropyl sulfonate (HAPS) and 100 parts of acrylate monomers were dispersed in 100 parts of water and pre-emulsified by high-speed stirring at 7000 rpm for 30 min to obtain the first emulsion. The first emulsion was transferred to a reactor, and 0.05 parts of α-bromophenyl ethane (EBiB), 0.03 parts of CuBr2 and 0.10 parts of 4,4'-dinonyl-2,2'-bipyridine (dNbpy) were added to the first emulsion. Nitrogen gas was purged for 30 min to remove oxygen, and the temperature was raised to 65°C under nitrogen atmosphere. Then, 0.1 parts of ascorbic acid were added and reacted for 12 h to obtain an acrylate polymer emulsion with a solid content of about 35% and a PDI of 1.21. (2) 1g of boron nitride nanosheets with an average particle size of 400 nm were dispersed in 100 mL of 50% methanol aqueous solution, 1g of 3-aminopropyltriethoxysilane was added, and the mixture was heated to 60℃ and refluxed for 7h. The reaction product was centrifuged to collect the precipitate, and the precipitate was washed with water and dried to obtain f-BNNS. 1.5 g of silver-coated copper nanowires (Ag@CuNWs, diameter 50 nm, length 10-20 μm) were dispersed in 100 mL of water, and then excess mercaptosuccinic acid was added. The mixture was stirred at room temperature for 8 h. The reaction product was centrifuged to collect the precipitate, and the precipitate was washed with water to obtain c-Ag@Cu NWs. By weight, 10 parts of f-BNNS and 10 parts of c-Ag@Cu NWs were dispersed in 150 mL of phosphate buffer at pH 7. 0.5 parts of EDC and 0.2 parts of NHS were added, and the amidation reaction was carried out at room temperature for 24 h. After centrifugation, the precipitate was collected, washed with water, and dried to obtain Ag@Cu NWs@f-BNNS.

[0030] (3) By weight, add 5 parts of f-BNNS to 100 parts of acrylate polymer emulsion, stir and shear disperse at 10000 rpm for 30 min, then add 10 parts of Ag@Cu NWs@f-BNNS and 3 parts of N-isopropylacrylamide, stir and disperse at 10000 rpm for 30 min, then add 0.5 parts of 2-hydroxy-2-methyl-1-phenyl-1-propanone or its derivative and 0.5 parts of blocked isocyanate, stir and mix at 300 rpm to obtain thermally conductive and conductive acrylate pressure-sensitive adhesive.

[0031] Comparative Example 1: Everything else is the same as in Example 1, except that: In step (3), the acrylate polymer emulsion prepared in this invention is replaced with a commercially available conventional acrylate emulsion (BASF Acronal® LR 9012) with an equal solids content.

[0032] Comparative Example 2: Everything else is the same as in Example 1, except that: In step (3), Ag@Cu NWs@f-BNNS is not added.

[0033] Comparative Example 3: Everything else is the same as in Example 1, except that: In step (3), Ag@Cu NWs@f-BNNS is replaced with Ag@Cu NWs.

[0034] Comparative Example 4: Everything else is the same as in Example 1, except that: In step (1), hydroxyethyl acrylate and acrylic acid are not added to the acrylate mixed monomers.

[0035] Comparative Example 5: Everything else is the same as in Example 1, except that: In step (1), isooctyl acrylate and methyl methacrylate are not added to the acrylate mixed monomers.

[0036] Comparative Example 6: Everything else is the same as in Example 1, except that: In step (1), hydroxyethyl acrylate and methyl methacrylate are not added to the acrylate mixed monomers.

[0037] Comparative Example 7: Everything else is the same as in Example 1, except that: In step (1), isooctyl acrylate and acrylic acid are not added to the acrylate mixed monomers.

[0038] Comparative Example 8: Everything else is the same as in Example 1, except that: In step (3), N-isopropylacrylamide is not added.

[0039] The acrylic pressure-sensitive adhesives prepared in Examples 1-3 and Comparative Examples 1-8 were uniformly coated onto PET films with a thickness of 40 μm, with a coating thickness of 25 μm. Then, a coating of 400 mJ / cm² was applied. 2 The coated acrylic pressure-sensitive adhesive wet layer is irradiated with ultraviolet light for initial curing, and then heat-treated at 70℃ for 15 minutes to complete curing, thus obtaining a protective film layer.

[0040] The protective film layer was subjected to comprehensive performance tests, including temperature-sensitive peel strength, electrical conductivity, and thermal conductivity. The method was as follows: The PET film covered with the protective film was placed in a constant temperature and humidity chamber and equilibrated for 24 hours at 25°C and 30% RH. The initial peel force of the protective film was measured. Each sample was measured three times and the average value was taken. The PET film covered with the protective film was left to stand for 5 minutes at 50°C and 30% RH. The temperature-sensitive peel strength of the protective film was measured. Each sample was measured three times and the average value was taken. The PET film covered with the protective film was equilibrated at 25°C and 80% RH for 24 hours. The high wet peel strength of the protective film was measured. Each sample was measured three times and the average value was taken. Calculate the temperature-sensitive change rate of the protective film peel force using the following formula: Thermosensitive peel force change rate = (initial peel force - thermosensitive peel force) / initial peel force × 100%; Calculate the humidity-sensitive change rate of protective film peel force using the following formula: Peel force humidity sensitivity change rate = (initial peel force - high humidity peel force) / initial peel force × 100%; The results are as follows: Table 1. Comprehensive performance test results of protective films cured with different acrylic pressure-sensitive adhesives

[0041] As can be seen from the results in Table 1, the test data of the protective films prepared in Examples 1-3 are better than those of Comparative Examples 1-8. The difference in the rate of change of peel force with humidity sensitivity among the groups is relatively small, indicating that the protective films of each group are not sensitive to humidity, and the change of humidity will not cause a large fluctuation in the peel force of the film.

[0042] As can be seen from Comparative Example 1, when commercially available conventional acrylic emulsions are used, the Ag@Cu NWs@f-BNNS filler is difficult to disperse evenly in the emulsion matrix due to the lack of a regular polymer structure in the emulsion matrix. This directly leads to a decrease in the thermal and electrical conductivity of the protective film. The inability of heat to be quickly conducted in the film layer further prevents the entire film from responding quickly to temperature increases, ultimately resulting in a significant reduction in the temperature-sensitive change rate of the peel force. In other words, the peel force cannot be reduced quickly in a short period of time when the temperature rises.

[0043] In Comparative Example 2, since no Ag@Cu NWs@f-BNNS filler was added, the entire film layer is an insulator with no electrical conductivity, and its thermal conductivity is also greatly reduced, resulting in a significant decrease in the temperature-sensitive response capability of the entire film.

[0044] Although the Ag@Cu NWs introduced in Comparative Example 3 has certain electrical and thermal conductivity, its performance is far inferior to that of Ag@Cu NWs@f-BNNS, resulting in a slowdown in the temperature-sensitive response speed of the entire film.

[0045] Comparative Examples 4-7 show that when some components are missing from the acrylate mixed monomers, the acrylate polymer emulsion prepared from the remaining monomers does not have a regular polymer matrix structure, which cannot guarantee the uniform dispersion of the filler. This affects the thermal and electrical conductivity of the film, resulting in a significant reduction in the temperature sensitivity of the entire film.

[0046] In Comparative Example 8, since no temperature-sensitive monomer was added, although the electrical and thermal conductivity of the film was not significantly reduced, the film did not have the ability to reduce peel strength as the temperature increased.

[0047] Furthermore, to verify the long-term reliability of the pressure-sensitive adhesive of this invention, the protective film obtained in Example 1 was subjected to a 500-hour thermal aging test at 85°C. The test results showed that after aging, its peel force temperature-sensitive change rate remained above 90% of its initial value, and the in-plane thermal conductivity and bulk conductivity both decreased by less than 10%, exhibiting excellent thermal stability and functional durability. Simultaneously, thanks to the highly efficient three-dimensional thermally conductive network constructed by Ag@Cu NWs@f-BNNS, the adhesive film of this invention exhibits rapid temperature-sensitive response characteristics. After rising from 25°C to 50°C, its peel force decreased to over 95% of its stable value within 2 minutes, significantly faster than the response speed of Comparative Example 1 (using a commercially available emulsion).

Claims

1. A method for preparing a thermally and electrically conductive acrylate pressure-sensitive adhesive, characterized in that, Includes the following steps: (1) Disperse the reactive emulsifier and the acrylate monomer mixture in water, emulsify to obtain the first emulsion, add alkyl halide, copper-based catalyst and nitrogen-containing ligand to the first emulsion, add water-soluble reducing agent under an inert atmosphere, heat to react and obtain acrylate polymer emulsion; (2) Boron nitride nanosheets were modified by silanization to obtain f-BNNS. f-BNNS was then subjected to amidation reaction with carboxylated silver-coated copper nanowires to obtain Ag@Cu NWs@f-BNNS with a core-shell structure. (3) Disperse f-BNNS in an acrylate polymer emulsion, then add Ag@Cu NWs@f-BNNS and thermo-responsive monomers, disperse and mix well, then add photoinitiator and latent curing agent and mix well to obtain thermally conductive and electrically conductive acrylate pressure-sensitive adhesive.

2. The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive according to claim 1, characterized in that, In step (1), the reactive emulsifier is sodium allyl hydroxypropyl sulfonate; the alkyl halide is α-bromophenylethane; the copper-based catalyst is copper halide; the nitrogen-containing ligand is 4,4'-dinonyl-2,2'-bipyridine; and the water-soluble reducing agent is ascorbic acid.

3. The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive according to claim 1, characterized in that, In step (1), the acrylate mixed monomers include isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid, and the heating reaction conditions are 60-70°C for 6-12 hours.

4. The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive according to claim 1, characterized in that, In step (2), the silanization modification method is as follows: Boron nitride nanosheets were dispersed in an aqueous alcohol solution, a silane coupling agent was added, and the mixture was heated under reflux. The reaction product was centrifuged to collect the precipitate, which was then washed and dried to obtain f-BNNS. The method for carboxylation treatment is as follows: Silver-coated copper nanowires were dispersed in water, and then excess mercaptosuccinic acid was added. The mixture was stirred at room temperature, and the reaction product was centrifuged to collect the precipitate. The precipitate was washed to obtain c-Ag@Cu NWs. The amidation reaction method is as follows: f-BNNS and c-Ag@Cu NWs were dispersed in a buffer solution, and carbodiimide and N-hydroxysuccinimide were added. After reacting at room temperature, the precipitate was collected by centrifugation. The precipitate was washed and dried to obtain Ag@Cu NWs@f-BNNS.

5. The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive according to claim 4, characterized in that, The boron nitride nanosheets have an average particle size of 400-600 nm, the aqueous solution of alcohol is a methanol or ethanol aqueous solution with a concentration of 50-75%, and the silane coupling agent is 3-aminopropyltriethoxysilane. The ratio of boron nitride nanosheets to an aqueous solution of alcohol is 1-5 g: 100-1000 mL; the heating and reflux conditions are reflux reaction at 60-90℃ for 3-7 h.

6. The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive according to claim 1, characterized in that, In step (3), the thermo-responsive monomer is N-isopropylacrylamide, the photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone or its derivative, and the latent curing agent is a blocked isocyanate.

7. The preparation method of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive according to claim 1, characterized in that, In step (3), the mass ratio of the acrylate polymer emulsion, the thermo-responsive monomer, Ag@Cu NWs@f-BNNS, the photoinitiator and the latent curing agent is 100:3-10:10-30:0.5-1.5:0.5-3.

5.

8. The application of the thermally conductive and electrically conductive acrylate pressure-sensitive adhesive prepared by the preparation method according to any one of claims 1-7 in the preparation of temporary protective films for flexible OLED screens or thermally conductive and electrically conductive adhesive interfaces for power battery modules.

9. The application according to claim 8, characterized in that, Includes the following steps: The thermally conductive and conductive acrylate pressure-sensitive adhesive is applied to the base film or bonding interface. The applied thermally conductive and conductive acrylate pressure-sensitive adhesive is first cured by ultraviolet light and then cured by heating.

10. The application according to claim 9, characterized in that, The energy intensity of the ultraviolet light is 300-500 mJ / cm. 2 The heating and curing method involves heat treatment at 60-80℃ for 10-20 minutes to complete the curing process.

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